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Sample records for protection cfd calculation

  1. Prediction of ash deposition using CFD simulation combined to thermodynamic calculation

    Energy Technology Data Exchange (ETDEWEB)

    Takeshi Muratani; Takashi Hongo [UBE Industries, Ltd., Yamaguchi (Japan). Coal Department, Energy and Environment Division

    2007-07-01

    This study focused on the advanced ash deposition prediction using computational fluid dynamics (CFD) analysis combined to thermodynamic calculation, considering both combustion characteristics and ash fusibility. Combustion field in pulverised coal-fired boiler was calculated through the normal CFD process. As the post process of combustion calculation, ash particles were injected into the combustion field to calculate ash deposition by CFD, in which particle sticking sub-program was newly employed. In this post process, ash deposition condition for CFD calculation was defined with the ash fusibility data obtained from thermodynamic analysis. These results of ash deposition on the furnace wall showed good agreement with the plant observation. Furthermore, in order to improve the plant operation, some virtual cases were simulated, which might reduce ash deposition. 7 refs., 14 figs., 6 tabs.

  2. Application of CFD based wave loads in aeroelastic calculations

    DEFF Research Database (Denmark)

    Schløer, Signe; Paulsen, Bo Terp; Bredmose, Henrik

    2014-01-01

    Two fully nonlinear irregular wave realizations with different significant wave heights are considered. The wave realizations are both calculated in the potential flow solver Ocean-Wave3D and in a coupled domain decomposed potential-flow CFD solver. The surface elevations of the calculated wave...... domain decomposed potentialflow CFD solver result in different dynamic forces in the tower and monopile, despite that the static forces on a fixed monopile are similar. The changes are due to differences in the force profiles and wave steepness in the two solvers. The results indicate that an accurate...

  3. Movable scour protection. CFD calculation of flow and scour around foundation

    Energy Technology Data Exchange (ETDEWEB)

    Miller, R.

    2002-07-01

    In the design of scour protections a basic parameter is the variation of the bed shear stress around the structure and the potential of the flow for using the stones of the scour protection. This report investigates whether it is: 1. Possible to calculate the correct bed shear stress for various wave and current situations at the base of the foundations, 2. Possible to calculate the scour depths with and without scour protection or in the case of movable scour protection. A number of test runs were made with the Elypsos computer code with the added morphological module (=sediment transport module). It turned out that it is possible to make such calculations but they are extremely time consuming on even a large computer for a simple structure like the circular foundation. It turns out that the computations overpredict the scour depth somewhat. Therefore a more practical approach was made. The morphological model was taken out. Instead the distribution of bottom shear stress distribution around the base of the structure was calculated. This is the important parameter for designing the armour layer of the scour protection. The Shields criterion was used for predicting stable stones and a suitable high value of the shear stress is used. The high bottom shear stress appears for a horizontal bottom. If the sea bottom is allowed to deepen in the areas with maximum shear stress amplification the horseshoe eddy is weakened. This again reduces the shear stress amplification. The computer program was used to perform such calculations and it turned out to be a powerful tool for this. The shear stress amplification can be reduced with a factor 2. Interactively, it is thus possible to calculate the form of a scour hole by trial and error. The scour protection surface shape with the smallest amplification of the shear stress and with the shear stress below the critical Shields Parameter is the optimum scour protection. The program can be used interactively to calculate the extent

  4. Hydraulics and heat transfer in the IFMIF liquid lithium target: CFD calculations

    OpenAIRE

    Peña, A.; Esteban, G.A.; Sancho, J.; Kolesnik, V.; Abánades Velasco, Alberto

    2009-01-01

    CFD (Computational fluid dynamics) calculation turns out to be a good approximation to the real behavior of the lithium (Li) flow of the target of the international fusion materials irradiation facility (IFMIF). A three-dimensional (3D) modelling of the IFMIF design Li target assembly, made with the CFD commercial code ANSYS-FLUENT has been carried out. The simulation by a structural mesh is focused on the thermal-hydraulic analysis inside the Li jet flow. For, this purpose, the two deuteron ...

  5. A coupled RELAPS-3D/CFD methodology with a proof-of-principle calculation; TOPICAL

    International Nuclear Information System (INIS)

    Aumiller, D.L.; Tomlinson, E.T.; Bauer, R.C.

    2000-01-01

    The RELAP5-3D computer code was modified to make the explicit coupling capability in the code fully functional. As a test of the modified code, a coupled RELAP5/RELAP5 analysis of the Edwards-O'Brien blowdown problem was performed which showed no significant deviations from the standard RELAP5-3D predictions. In addition, a multiphase Computational Fluid Dynamics (CFD) code was modified to permit explicit coupling to RELAP5-3D. Several calculations were performed with this code. The first analysis used the experimental pressure history from a point just upstream of the break as a boundary condition. This analysis showed that a multiphase CFD code could calculate the thermodynamic and hydrodynamic conditions during a rapid blowdown transient. Finally, a coupled RELAP5/CFD analysis was performed. The results are presented in this paper

  6. Optimized design for TWR assembly by CFD calculations

    International Nuclear Information System (INIS)

    Lu Jianchao; Lu Chuan; Yan Mingyu

    2013-01-01

    High temperature difference in travelling wave reactor bundle was found in the previous work. It could not be used in bundle design. Various analysis focused on helical wrapped wires and assembly housing was carried out by CFD calculation which found that the helical wrapped wires could influence the temperature differences while the effect was not obvious. Adding the strips and fillets on the assembly housing could optimize the thermal characteristics greatly, which can be used in the TWR assembly design. (authors)

  7. Coupling calculation of CFD-ACE computational fluid dynamics code and DeCART whole-core neutron transport code for development of numerical reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Chang Hwan; Seo, Kyong Won; Chun, Tae Hyun; Kim, Kang Seog

    2005-03-15

    Code coupling activities have so far focused on coupling the neutronics modules with the CFD module. An interface module for the CFD-ACE/DeCART coupling was established as an alternative to the original STAR-CD/DeCART interface. The interface module for DeCART/CFD-ACE was validated by single-pin model. The optimized CFD mesh was decided through the calculation of multi-pin model. It was important to consider turbulent mixing of subchannels for calculation of fuel temperature. For the parallel calculation, the optimized decompose process was necessary to reduce the calculation costs and setting of the iteration and convergence criterion for each code was important, too.

  8. Coupling calculation of CFD-ACE computational fluid dynamics code and DeCART whole-core neutron transport code for development of numerical reactor

    International Nuclear Information System (INIS)

    Shin, Chang Hwan; Seo, Kyong Won; Chun, Tae Hyun; Kim, Kang Seog

    2005-03-01

    Code coupling activities have so far focused on coupling the neutronics modules with the CFD module. An interface module for the CFD-ACE/DeCART coupling was established as an alternative to the original STAR-CD/DeCART interface. The interface module for DeCART/CFD-ACE was validated by single-pin model. The optimized CFD mesh was decided through the calculation of multi-pin model. It was important to consider turbulent mixing of subchannels for calculation of fuel temperature. For the parallel calculation, the optimized decompose process was necessary to reduce the calculation costs and setting of the iteration and convergence criterion for each code was important, too

  9. Combined Uncertainty and A-Posteriori Error Bound Estimates for General CFD Calculations: Theory and Software Implementation

    Science.gov (United States)

    Barth, Timothy J.

    2014-01-01

    This workshop presentation discusses the design and implementation of numerical methods for the quantification of statistical uncertainty, including a-posteriori error bounds, for output quantities computed using CFD methods. Hydrodynamic realizations often contain numerical error arising from finite-dimensional approximation (e.g. numerical methods using grids, basis functions, particles) and statistical uncertainty arising from incomplete information and/or statistical characterization of model parameters and random fields. The first task at hand is to derive formal error bounds for statistics given realizations containing finite-dimensional numerical error [1]. The error in computed output statistics contains contributions from both realization error and the error resulting from the calculation of statistics integrals using a numerical method. A second task is to devise computable a-posteriori error bounds by numerically approximating all terms arising in the error bound estimates. For the same reason that CFD calculations including error bounds but omitting uncertainty modeling are only of limited value, CFD calculations including uncertainty modeling but omitting error bounds are only of limited value. To gain maximum value from CFD calculations, a general software package for uncertainty quantification with quantified error bounds has been developed at NASA. The package provides implementations for a suite of numerical methods used in uncertainty quantification: Dense tensorization basis methods [3] and a subscale recovery variant [1] for non-smooth data, Sparse tensorization methods[2] utilizing node-nested hierarchies, Sampling methods[4] for high-dimensional random variable spaces.

  10. Application of CFD dispersion calculation in risk based inspection for release of H2S

    International Nuclear Information System (INIS)

    Sharma, Pavan K.; Vinod, Gopika; Singh, R.K.; Rao, V.V.S.S.; Vaze, K.K.

    2011-01-01

    In atmospheric dispersion both deterministic and probabilistic approached have been used for addressing design and regulatory concerns. In context of deterministic calculations the amount of pollutants dispersion in the atmosphere is an important area wherein different approaches are followed in development of good analytical model. The analysis based on Computational Fluid Dynamics (CFD) codes offer an opportunity of model development based on first principles of physics and hence such models have an edge over the existing models. In context of probabilistic methods applying risk based inspection (wherein consequence of failure from each component needs to be assessed) are becoming popular. Consequence evaluation in a process plant is a crucial task. Often the number of components considered for life management will be too huge. Also consequence evaluation of all the components proved to be laborious task. The present paper is the results of joint collaborative work from deterministic and probabilistic modelling group working in the field of atmospheric dispersion. Even though API 581 has simplified qualitative approach, regulators find the some of the factors, in particular, quantity factor, not suitable for process plants. Often dispersion calculations for heavy gas are done with very simple model which can not take care of density based atmospheric dispersion. This necessitates a new approach with a CFD based technical basis is proposed, so that the range of quantity considered along with factors used can be justified. The present paper is aimed at bringing out some of the distinct merits and demerits of the CFD based models. A brief account of the applications of such CFD codes reported in literature is also presented in the paper. This paper describes the approach devised and demonstrated for the said issue with emphasis of CFD calculations. (author)

  11. Comparison of CFD-calculations of centrifugal compressor stages by NUMECA Fine Turbo and ANSYS CFX programs

    Science.gov (United States)

    Galerkin, Y. B.; Voinov, I. B.; Drozdov, A. A.

    2017-08-01

    Computational Fluid Dynamics (CFD) methods are widely used for centrifugal compressors design and flow analysis. The calculation results are dependent on the chosen software, turbulence models and solver settings. Two of the most widely applicable programs are NUMECA Fine Turbo and ANSYS CFX. The objects of the study were two different stages. CFD-calculations were made for a single blade channel and for full 360-degree flow paths. Stage 1 with 3D impeller and vaneless diffuser was tested experimentally. Its flow coefficient is 0.08 and loading factor is 0.74. For stage 1 calculations were performed with different grid quality, a different number of cells and different models of turbulence. The best results have demonstrated the Spalart-Allmaras model and mesh with 1.854 million cells. Stage 2 with return channel, vaneless diffuser and 3D impeller with flow coefficient 0.15 and loading factor 0.5 was designed by the known Universal Modeling Method. Its performances were calculated by the well identified Math model. Stage 2 performances by CFD calculations shift to higher flow rate in comparison with design performances. The same result was obtained for stage 1 in comparison with measured performances. Calculated loading factor is higher in both cases for a single blade channel. Loading factor performance calculated for full flow path (“360 degrees”) by ANSYS CFX is in satisfactory agreement with the stage 2 design performance. Maximum efficiency is predicted accurately by the ANSYS CFX “360 degrees” calculation. “Sector” calculation is less accurate. Further research is needed to solve the problem of performances mismatch.

  12. Real-time POD-CFD Wind-Load Calculator for PV Systems

    Energy Technology Data Exchange (ETDEWEB)

    Huayamave, Victor [Centecorp; Divo, Eduardo [Centecorp; Ceballos, Andres [Centecorp; Barriento, Carolina [Centecorp; Stephen, Barkaszi [FSEC; Hubert, Seigneur [FSEC

    2014-03-21

    The primary objective of this project is to create an accurate web-based real-time wind-load calculator. This is of paramount importance for (1) the rapid and accurate assessments of the uplift and downforce loads on a PV mounting system, (2) identifying viable solutions from available mounting systems, and therefore helping reduce the cost of mounting hardware and installation. Wind loading calculations for structures are currently performed according to the American Society of Civil Engineers/ Structural Engineering Institute Standard ASCE/SEI 7; the values in this standard were calculated from simplified models that do not necessarily take into account relevant characteristics such as those from full 3D effects, end effects, turbulence generation and dissipation, as well as minor effects derived from shear forces on installation brackets and other accessories. This standard does not include provisions that address the special requirements of rooftop PV systems, and attempts to apply this standard may lead to significant design errors as wind loads are incorrectly estimated. Therefore, an accurate calculator would be of paramount importance for the preliminary assessments of the uplift and downforce loads on a PV mounting system, identifying viable solutions from available mounting systems, and therefore helping reduce the cost of the mounting system and installation. The challenge is that although a full-fledged three-dimensional computational fluid dynamics (CFD) analysis would properly and accurately capture the complete physical effects of air flow over PV systems, it would be impractical for this tool, which is intended to be a real-time web-based calculator. CFD routinely requires enormous computation times to arrive at solutions that can be deemed accurate and grid-independent even in powerful and massively parallel computer platforms. This work is expected not only to accelerate solar deployment nationwide, but also help reach the SunShot Initiative goals

  13. Assessment of the 3He pressure inside the CABRI transient rods - Development of a surrogate model based on measurements and complementary CFD calculations

    Science.gov (United States)

    Clamens, Olivier; Lecerf, Johann; Hudelot, Jean-Pascal; Duc, Bertrand; Cadiou, Thierry; Blaise, Patrick; Biard, Bruno

    2018-01-01

    CABRI is an experimental pulse reactor, funded by the French Nuclear Safety and Radioprotection Institute (IRSN) and operated by CEA at the Cadarache research center. It is designed to study fuel behavior under RIA conditions. In order to produce the power transients, reactivity is injected by depressurization of a neutron absorber (3He) situated in transient rods inside the reactor core. The shapes of power transients depend on the total amount of reactivity injected and on the injection speed. The injected reactivity can be calculated by conversion of the 3He gas density into units of reactivity. So, it is of upmost importance to properly master gas density evolution in transient rods during a power transient. The 3He depressurization was studied by CFD calculations and completed with measurements using pressure transducers. The CFD calculations show that the density evolution is slower than the pressure drop. Surrogate models were built based on CFD calculations and validated against preliminary tests in the CABRI transient system. Studies also show that it is harder to predict the depressurization during the power transients because of neutron/3He capture reactions that induce a gas heating. This phenomenon can be studied by a multiphysics approach based on reaction rate calculation thanks to Monte Carlo code and study the resulting heating effect with the validated CFD simulation.

  14. Assessment of the 3He pressure inside the CABRI transient rods - Development of a surrogate model based on measurements and complementary CFD calculations

    Directory of Open Access Journals (Sweden)

    Clamens Olivier

    2018-01-01

    Full Text Available CABRI is an experimental pulse reactor, funded by the French Nuclear Safety and Radioprotection Institute (IRSN and operated by CEA at the Cadarache research center. It is designed to study fuel behavior under RIA conditions. In order to produce the power transients, reactivity is injected by depressurization of a neutron absorber (3He situated in transient rods inside the reactor core. The shapes of power transients depend on the total amount of reactivity injected and on the injection speed. The injected reactivity can be calculated by conversion of the 3He gas density into units of reactivity. So, it is of upmost importance to properly master gas density evolution in transient rods during a power transient. The 3He depressurization was studied by CFD calculations and completed with measurements using pressure transducers. The CFD calculations show that the density evolution is slower than the pressure drop. Surrogate models were built based on CFD calculations and validated against preliminary tests in the CABRI transient system. Studies also show that it is harder to predict the depressurization during the power transients because of neutron/3He capture reactions that induce a gas heating. This phenomenon can be studied by a multiphysics approach based on reaction rate calculation thanks to Monte Carlo code and study the resulting heating effect with the validated CFD simulation.

  15. CFD-calculations to a core catcher benchmark

    International Nuclear Information System (INIS)

    Willschuetz, H.G.

    1999-04-01

    There are numerous experiments for the exploration of the corium spreading behaviour, but comparable data have not been available up to now in the field of the long term behaviour of a corium expanded in a core catcher. The difficulty consists in the experimental simulation of the decay heat that can be neglected for the short-run course of events like relocation and spreading, which must, however, be considered during investigation of the long time behaviour. Therefore the German GRS, defined together with Battelle Ingenieurtechnik a benchmark problem in order to determine particular problems and differences of CFD codes simulating an expanded corium and from this, requirements for a reasonable measurement of experiments, that will be performed later. First the finite-volume-codes Comet 1.023, CFX 4.2 and CFX-TASCflow were used. To be able to make comparisons to a finite-element-code, now calculations are performed at the Institute of Safety Research at the Forschungszentrum Rossendorf with the code ANSYS/FLOTRAN. For the benchmark calculations of stage 1 a pure and liquid melt with internal heat sources was assumed uniformly distributed over the area of the planned core catcher of a EPR plant. Using the Standard-k-ε-turbulence model and assuming an initial state of a motionless superheated melt several large convection rolls will establish within the melt pool. The temperatures at the surface do not sink to a solidification level due to the enhanced convection heat transfer. The temperature gradients at the surface are relatively flat while there are steep gradients at the ground where the no slip condition is applied. But even at the ground no solidification temperatures are observed. Although the problem in the ANSYS-calculations is handled two-dimensional and not three-dimensional like in the finite-volume-codes, there are no fundamental deviations to the results of the other codes. (orig.)

  16. Short-Term Wind Power Forecasting Based on Clustering Pre-Calculated CFD Method

    Directory of Open Access Journals (Sweden)

    Yimei Wang

    2018-04-01

    Full Text Available To meet the increasing wind power forecasting (WPF demands of newly built wind farms without historical data, physical WPF methods are widely used. The computational fluid dynamics (CFD pre-calculated flow fields (CPFF-based WPF is a promising physical approach, which can balance well the competing demands of computational efficiency and accuracy. To enhance its adaptability for wind farms in complex terrain, a WPF method combining wind turbine clustering with CPFF is first proposed where the wind turbines in the wind farm are clustered and a forecasting is undertaken for each cluster. K-means, hierarchical agglomerative and spectral analysis methods are used to establish the wind turbine clustering models. The Silhouette Coefficient, Calinski-Harabaz index and within-between index are proposed as criteria to evaluate the effectiveness of the established clustering models. Based on different clustering methods and schemes, various clustering databases are built for clustering pre-calculated CFD (CPCC-based short-term WPF. For the wind farm case studied, clustering evaluation criteria show that hierarchical agglomerative clustering has reasonable results, spectral clustering is better and K-means gives the best performance. The WPF results produced by different clustering databases also prove the effectiveness of the three evaluation criteria in turn. The newly developed CPCC model has a much higher WPF accuracy than the CPFF model without using clustering techniques, both on temporal and spatial scales. The research provides supports for both the development and improvement of short-term physical WPF systems.

  17. Derivation of airfoil characteristics for the LM 19.1 blade based on 3D CFD rotor calculations

    Energy Technology Data Exchange (ETDEWEB)

    Bak, C; Soerensen, N N; Madsen, H A [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    Airfoil characteristics for the LM 19.1 blade are derived from 3D CFD computations on a full-scale 41-m rotor. Based on 3D CFD the force distributions on the blades are determined, from which airfoil characteristics are derived using the momentum theory. The final airfoil characteristics are constructed using both wind tunnel measurements and 3D CFD. Compared to 2D wind tunnel measurements they show a low lift in stall for the airfoil sections at the tip. At the airfoil sections at the inner part of the blade, they show a high lift in stall. At about 60% radius the lift agrees well to 2D wind tunnel measurements. Aero-elastic calculations using the final airfoil characteristics show good agreement to measured power and flap moments. Furthermore, a fatigue load analysis shows a reduction of up to 15% of the load compared to commonly used data. (au)

  18. CFD Model Data

    Data.gov (United States)

    U.S. Environmental Protection Agency — Data associated with the development of the CFD model for spore deposition in respiratory systems of rabbits and humans. This dataset is associated with the...

  19. Safety Injection Tank Performance Analysis Using CFD

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jai Oan; Lee, Jeong Ik; Nietiadi Yohanes Setiawan [KAIST, Daejeon (Korea, Republic of); Addad Yacine [KUSTAR, Abu Dhabi (United Arab Emirates); Bang, Young Seok; Yoo, Seung Hun [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2016-10-15

    This may affect the core cooling capability and threaten the fuel integrity during LOCA situations. However, information on the nitrogen flow rate during discharge is very limited due to the associated experimental measurement difficulties, and these phenomena are hardly reflected in current 1D system codes. In the current study, a CFD analysis is presented which hopefully should allow obtaining a more realistic prediction of the SIT performance which can then be reflected on 1D system codes to simulate various accident scenarios. Current Computational Fluid Dynamics (CFD) calculations have had limited success in predicting the fluid flow accurately. This study aims to find a better CFD prediction and more accurate modeling to predict the system performance during accident scenarios. The safety injection tank with fluidic device was analyzed using commercial CFD. A fine resolution grid was used to capture the vortex of the fluidic device. The calculation so far has shown good consistency with the experiment. Calculation should complete by the conference date and will be thoroughly analyzed to be discussed. Once a detailed CFD computation is finished, a small-scale experiment will be conducted for the given conditions. Using the experimental results and the CFD model, physical models can be validated to give more reliable results. The data from CFD and experiments will provide a more accurate K-factor of the fluidic device which can later be applied in system code inputs.

  20. Flow oscillations on the steam control valve in the middle opening condition. Clarification of the phenomena by steam flow experiment and CFD calculation

    International Nuclear Information System (INIS)

    Morita, Ryo; Inada, Fumio

    2006-01-01

    A steam control valve might cause vibrations of piping when the valve opening is in a middle condition. For rationalization of maintenance and management of the plant, the valve should be improved, but it is difficult to understand flow characteristics in detail by experiment because flow around the valve is complex 3D structure and becomes supersonic (M>1). Therefore, it is necessary to clarify the cause of the vibrations and to develop improvements by Computational Fluid Dynamics (CFD) technology. In previous researches, we clarified a mechanism of the pressure fluctuations in the middle opening condition and suggested the way to prevent the pressure fluctuations by experiments and CFD calculations. But, as we used air as a working fluid in our previous research instead of steam that is used in the power plant, we couldn't consider effects of condensation and difference of change of the quantity of state between air and steam. In this report, we have conducted steam flow experiments by multi-purpose steam experiment apparatus 'WISSH' and CFD calculations by steam flow code 'MATIS-SC' to clarify those effects. As a result, in the middle opening condition, we have observed rotating pressure fluctuations in the experiment and valve-attached flow and local high-pressure region in the CFD result. These results show the pressure fluctuations in steam experiments and CFD is same kind of the fluctuations found in air experiment and CFD. (author)

  1. CFD aided analysis of a scaled down model of the Brazilian Multipurpose Reactor (RMB) pool

    International Nuclear Information System (INIS)

    Schweizer, Fernando L.A.; Lima, Claubia P.B.; Costa, Antonella L.; Veloso, Maria A.F.

    2013-01-01

    Research reactors are commonly built inside deep pools that provide radiological and thermal protection and easy access to its core. Reactors with thermal power in the order of MW usually use an auxiliary thermal-hydraulic circuit at the top of its pool to create a purified hot water layer (HWL). Thermal-hydraulic analysis of the flow configuration in the pool and HWL is paramount to insure radiological protection. A useful tool for these analyses is the application of CFD (Computational Fluid Dynamics). To obtain satisfactory results using CFD it is necessary the verification and validation of the CFD numerical model. Verification is divided in code and solution verifications. In the first one establishes the correctness of the CFD code implementation and in the former estimates the numerical accuracy of a particular calculation. Validation is performed through comparison of numerical and experimental results. This paper presents a dimensional analysis of the RMB (Brazilian Multipurpose Reactor) pool to determine a scaled down experimental installation able to aid in the HWL numerical investigation. Two CFD models were created one with the same dimensions and boundary conditions of the reactor prototype and the other with 1/10 proportion size and boundary conditions set to achieve the same inertial and buoyant forces proportions represented by Froude Number between the two models. Results comparing the HWL thickness show consistence between the prototype and the scaled down model behavior. (author)

  2. Accumulation and transport of microbial-size particles in a pressure protected model burn unit: CFD simulations and experimental evidence

    Directory of Open Access Journals (Sweden)

    Mimoun Maurice

    2011-03-01

    enter into the positive pressure room when the access door was opened, while 2°C had little effect. Based on these findings the constructed burn unit was outfitted with supplemental air exhaust ducts over the doors to compensate for the thermal convective flows. Conclusions CFD simulations proved to be a particularly useful tool for the design and optimization of a burn unit treatment room. Our results, which have been confirmed qualitatively by experimental investigation, stressed that airborne transfer of microbial size particles via thermal convection flows are able to bypass the protective overpressure in the patient room, which can represent a potential risk of cross contamination between rooms in protected environments.

  3. EXAMINATION OF A PROPOSED VALIDATION DATA SET USING CFD CALCULATIONS

    International Nuclear Information System (INIS)

    Johnson, Richard W.

    2009-01-01

    The United States Department of Energy is promoting the resurgence of nuclear power in the U. S. for both electrical power generation and production of process heat required for industrial processes such as the manufacture of hydrogen for use as a fuel in automobiles. The DOE project is called the next generation nuclear plant (NGNP) and is based on a Generation IV reactor concept called the very high temperature reactor (VHTR), which will use helium as the coolant at temperatures ranging from 450 C to perhaps 1000 C. While computational fluid dynamics (CFD) has not been used for past safety analysis for nuclear reactors in the U. S., it is being considered for such for future reactors. It is fully recognized that CFD simulation codes will have to be validated for flow physics reasonably close to actual fluid dynamic conditions expected in normal and accident operational situations. To this end, experimental data have been obtained in a scaled model of a narrow slice of the lower plenum of a prismatic VHTR. The present article presents new results of CFD examinations of these data to explore potential issues with the geometry, the initial conditions, the flow dynamics and the data needed to fully specify the inlet and boundary conditions; results for several turbulence models are examined. Issues are addressed and recommendations about the data are made

  4. The development and application of CFD technology in mechanical engineering

    Science.gov (United States)

    Wei, Yufeng

    2017-12-01

    Computational Fluid Dynamics (CFD) is an analysis of the physical phenomena involved in fluid flow and heat conduction by computer numerical calculation and graphical display. The numerical method simulates the complexity of the physical problem and the precision of the numerical solution, which is directly related to the hardware speed of the computer and the hardware such as memory. With the continuous improvement of computer performance and CFD technology, it has been widely applied to the field of water conservancy engineering, environmental engineering and industrial engineering. This paper summarizes the development process of CFD, the theoretical basis, the governing equations of fluid mechanics, and introduces the various methods of numerical calculation and the related development of CFD technology. Finally, CFD technology in the mechanical engineering related applications are summarized. It is hoped that this review will help researchers in the field of mechanical engineering.

  5. CFD Analysis of the Safety Injection Tank and Fluidic Device

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jai Oan; Nietiadi, Yohanes Setiawan; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of); Addad, Yacine [KUSTAR, Abu Dhabi (United Arab Emirates)

    2016-05-15

    One of the most important components in the ECCS is the safety injection tank (SIT). Inside the SIT, a fluidic device is installed, which passively controls the mass flow of the safety injection and eliminates the need for low pressure safety injection pumps. As more passive safety mechanisms are being pursued, it has become more important to understand flow structure and the loss mechanism within the fluidic device. Current computational fluid dynamics (CFD) calculations have had limited success in predicting the fluid flow accurately. This study proposes to find a more exact result using CFD and more realistic modeling to predict the performance during accident scenarios more accurately. The safety injection tank with fluidic device was analyzed thoroughly using CFD. The preliminary calculation used 60,000 meshes for the initial test calculation. The results fit the experimental results surprisingly despite its coarse grid. Nonetheless, the mesh resolution was increased to capture the vortex in the fluidic device precisely. Once a detailed CFD computation is finished, a small-scale experiment will be conducted for the given conditions. Using the experimental results and the CFD model, physical models can be improved to fit the results more accurately.

  6. The difference between traditional experiments and CFD validation benchmark experiments

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Barton L., E-mail: barton.smith@usu.edu

    2017-02-15

    Computation Fluid Dynamics provides attractive features for design, and perhaps licensing, of nuclear power plants. The most important of these features is low cost compared to experiments. However, uncertainty of CFD calculations must accompany these calculations in order for the results to be useful for important decision making. In order to properly assess the uncertainty of a CFD calculation, it must be “validated” against experimental data. Unfortunately, traditional “discovery” experiments are normally ill-suited to provide all of the information necessary for the validation exercise. Traditionally, experiments are performed to discover new physics, determine model parameters, or to test designs. This article will describe a new type of experiment; one that is designed and carried out with the specific purpose of providing Computational Fluid Dynamics (CFD) validation benchmark data. We will demonstrate that the goals of traditional experiments and validation experiments are often in conflict, making use of traditional experimental results problematic and leading directly to larger predictive uncertainty of the CFD model.

  7. The difference between traditional experiments and CFD validation benchmark experiments

    International Nuclear Information System (INIS)

    Smith, Barton L.

    2017-01-01

    Computation Fluid Dynamics provides attractive features for design, and perhaps licensing, of nuclear power plants. The most important of these features is low cost compared to experiments. However, uncertainty of CFD calculations must accompany these calculations in order for the results to be useful for important decision making. In order to properly assess the uncertainty of a CFD calculation, it must be “validated” against experimental data. Unfortunately, traditional “discovery” experiments are normally ill-suited to provide all of the information necessary for the validation exercise. Traditionally, experiments are performed to discover new physics, determine model parameters, or to test designs. This article will describe a new type of experiment; one that is designed and carried out with the specific purpose of providing Computational Fluid Dynamics (CFD) validation benchmark data. We will demonstrate that the goals of traditional experiments and validation experiments are often in conflict, making use of traditional experimental results problematic and leading directly to larger predictive uncertainty of the CFD model.

  8. CFD - neutronic coupled calculation of a quarter of a simplified PWR fuel assembly including spacer pressure drop and turbulence enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Pena, C.; Pellacani, F.; Macian Juan, R., E-mail: carlos.pena@ntech.mw.tum.de, E-mail: pellacani@ntech.mw.tum.de, E-mail: macian@ntech.mw.tum.de [Technische Universitaet Muenchen, Garching (Germany). Ntech Lehrstuhl fuer Nukleartechnik; Chiva, S., E-mail: schiva@emc.uji.es [Universitat Jaume I, Castellon de la Plana (Spain). Dept. de Ingenieria Mecanica y Construccion; Barrachina, T.; Miro, R., E-mail: rmiro@iqn.upv.es, E-mail: tbarrachina@iqn.upv.es [Universitat Politecnica de Valencia (ISIRYM/UPV) (Spain). Institute for Industrial, Radiophysical and Environmental Safety

    2011-07-01

    A computational code system based on coupling the 3D neutron diffusion code PARCS v2.7 and the Ansys CFX 13.0 Computational Fluid Dynamics (CFD) code has been developed as a tool for nuclear reactor systems simulations. This paper presents the coupling methodology between the CFD and the neutronic code. The methodology to simulate a 3D-neutronic problem coupled with 1D thermal hydraulics is already a mature technology, being part of the regular calculations performed to analyze different kinds of Reactivity Insertion Accidents (RIA) and asymmetric transients in Nuclear Power Plants, with state-of-the-art coupled codes like TRAC-B/NEM, RELAP5/PARCS, TRACE/PARCS, RELAP3D, RETRAN3D, etc. This work represents one of the first attempts to couple the multiphysics of a nuclear reactor core with a 3D spatial resolution in a computer code. This will open new possibilities regarding the analysis of fuel elements, contributing to a better understanding and design of the heat transfer process and specific fluid dynamics phenomena such as cross flow among fuel elements. The transient simulation of control rod insertion, boron dilution and cold water injection will be made possible with a degree of accuracy not achievable with current methodologies based on the use of system and/or subchannel codes. The transport of neutrons depends on several parameters, like fuel temperature, moderator temperature and density, boron concentration and fuel rod insertion. These data are calculated by the CFD code with high local resolution and used as input to the neutronic code to calculate a 3D nodal power distribution that will be returned and remapped to the CFD code control volumes (cells). Since two different nodalizations are used to discretized the same system, an averaging and interpolating procedure is needed to realize an effective data exchange. These procedures have been developed by means of the Ansys CFX 'User Fortran' interface; a library with several subroutines has

  9. CFD - neutronic coupled calculation of a quarter of a simplified PWR fuel assembly including spacer pressure drop and turbulence enhancement

    International Nuclear Information System (INIS)

    Pena, C.; Pellacani, F.; Macian Juan, R.; Chiva, S.; Barrachina, T.; Miro, R.

    2011-01-01

    A computational code system based on coupling the 3D neutron diffusion code PARCS v2.7 and the Ansys CFX 13.0 Computational Fluid Dynamics (CFD) code has been developed as a tool for nuclear reactor systems simulations. This paper presents the coupling methodology between the CFD and the neutronic code. The methodology to simulate a 3D-neutronic problem coupled with 1D thermal hydraulics is already a mature technology, being part of the regular calculations performed to analyze different kinds of Reactivity Insertion Accidents (RIA) and asymmetric transients in Nuclear Power Plants, with state-of-the-art coupled codes like TRAC-B/NEM, RELAP5/PARCS, TRACE/PARCS, RELAP3D, RETRAN3D, etc. This work represents one of the first attempts to couple the multiphysics of a nuclear reactor core with a 3D spatial resolution in a computer code. This will open new possibilities regarding the analysis of fuel elements, contributing to a better understanding and design of the heat transfer process and specific fluid dynamics phenomena such as cross flow among fuel elements. The transient simulation of control rod insertion, boron dilution and cold water injection will be made possible with a degree of accuracy not achievable with current methodologies based on the use of system and/or subchannel codes. The transport of neutrons depends on several parameters, like fuel temperature, moderator temperature and density, boron concentration and fuel rod insertion. These data are calculated by the CFD code with high local resolution and used as input to the neutronic code to calculate a 3D nodal power distribution that will be returned and remapped to the CFD code control volumes (cells). Since two different nodalizations are used to discretized the same system, an averaging and interpolating procedure is needed to realize an effective data exchange. These procedures have been developed by means of the Ansys CFX 'User Fortran' interface; a library with several subroutines has been

  10. Aeroelastic Calculations Using CFD for a Typical Business Jet Model

    Science.gov (United States)

    Gibbons, Michael D.

    1996-01-01

    Two time-accurate Computational Fluid Dynamics (CFD) codes were used to compute several flutter points for a typical business jet model. The model consisted of a rigid fuselage with a flexible semispan wing and was tested in the Transonic Dynamics Tunnel at NASA Langley Research Center where experimental flutter data were obtained from M(sub infinity) = 0.628 to M(sub infinity) = 0.888. The computational results were computed using CFD codes based on the inviscid TSD equation (CAP-TSD) and the Euler/Navier-Stokes equations (CFL3D-AE). Comparisons are made between analytical results and with experiment where appropriate. The results presented here show that the Navier-Stokes method is required near the transonic dip due to the strong viscous effects while the TSD and Euler methods used here provide good results at the lower Mach numbers.

  11. Measurement and CFD calculation of spacer loss coefficient for a tight-lattice fuel bundle

    International Nuclear Information System (INIS)

    In, Wang Kee; Shin, Chang Hwan; Kwack, Young Kyun; Lee, Chi Young

    2015-01-01

    Highlights: • Experiment and CFD analysis evaluated the pressure drop in a spacer grid. • The measurement and CFD errors for the spacer loss coefficient were estimated. • The spacer loss coefficient for the dual-cooled annular fuel bundle was determined. • The CFD prediction agrees with the measured spacer loss coefficient within 8%. - Abstract: An experiment and computational fluid dynamics (CFD) analysis were performed to evaluate the pressure drop in a spacer grid for a dual-cooled annular fuel (DCAF) bundle. The DCAF bundle for the Korean optimum power reactor (OPR1000) is a 12 × 12 tight-lattice rod array with a pitch-to-diameter ratio of 1.08 owing to a larger outer diameter of the annular fuel rod. An experiment was conducted to measure the pressure drop in spacer grid for the DCAF bundle. The test bundle is a full-size 12 × 12 rod bundle with 11 spacer grid. The test condition covers a Reynolds number range of 2 × 10 4 –2 × 10 5 by changing the temperature and flow rate of water. A CFD analysis was also performed to predict the pressure drop through a spacer grid using the full-size and partial bundle models. The pressure drop and loss coefficient of a spacer grid were predicted and compared with the experimental results. The CFD predictions of spacer pressure drop and loss coefficient agree with the measured values within 8%. The spacer loss coefficient for the DCAF bundle is estimated to be approximately 1.50 at a nominal operating condition of OPR1000, i.e., Re = 4 × 10 5

  12. Computer automation for protection factor calculations of buildings

    International Nuclear Information System (INIS)

    Farafat, M.A.Z.; Madian, A.H.

    2011-01-01

    The protection factors of buildings are different according to the constructional and architectural specifications. Uk and USA performed a calculation using manual method to calculate the protection factor for any building which may protect the people in it from gamma rays and fall-out.The manual calculation method is very complex which is very difficult to use, for that reason the researchers simplify this method in proposed form which will be easy to understand and use. Also the researchers have designed a computer program ,in visual basic, to calculate the different protection factors for buildings. The program aims to provide the missing time in the calculation processes to calculate the protection in some spaces for any building through entering specifications data for any building .The program will modify the protection factor in very short time which will save the effort and time in comparison with the manual calculation.

  13. CFD calculation of a catalyst near the engine connected in series with an exhaust turbocharger; CFD-Berechnung fuer einen motornahen Katalysator nach Abgasturbolader

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, R.; Olesen, M. [Zeuna Staerker GmbH und Co. KG (Germany)

    2002-06-01

    Under the pressure of ever shorter development times and high demands on exhaust systems in terms of exhaust counterpressure, acoustic and sensory aspects and exhaust purification, Zeuna Staerker started at an early stage to use advanced CFD methods in their product development process. The contribution investigates the effects of simplified assumptions of boundary conditions, using laser optical flow measurements on a turbocharger with a catalyst near the engine. [German] Immer kuerzer werdende Entwicklungszeiten und die hohen Anforderungen an Abgasanlagen hinsichtlich Abgasgegendruck, Akustik, Sensorik und Abgasreinigung fuehrten bei Zeuna Staerker schon fruehzeitig zur Etablierung ausgereifter CFD-Methoden im Produktentwicklungsprozess. Doch wie stark werden CFD-Berechnungen durch die aufgepraegten Randbedingungen beeinflusst, wenn diese nach Abgasturbolader oft vereinfacht angenommen werden muessen? Mit Hilfe laseroptischer Stroemungsmessungen an einem Abgasturbolader mit motornahem Katalysator wird dieser Frage nachgegangen. (orig.)

  14. CFD calculations on the IFMIF Li-jet fluid dynamics

    International Nuclear Information System (INIS)

    Casal, N.

    2007-01-01

    IFMIF is an accelerator-based neutron source to test fusion candidate materials, in which two deuteron beams will strike a target of liquid lithium. The deuteron-lithium stripping reactions will produce the required energy neutron flux to simulate the fusion reactor irradiation. The lithium jet must remove up to 10 MW of beam power deposited on it, so a lithium velocity as high as 20 m/s is required in the target. In addition, in the beam power deposition area, the lithium flows over a concave backwall so that the centrifugal forces avoid lithium boiling. A stable liquid free surface is a very critical requirement of the target system, otherwise the neutron field could be altered. In this line, 1mm of amplitude has been established as the limit of lithium free surface perturbations in IFMIF present design. The experimental results of a number of water and lithium facilities together with previous fluiddynamics calculations show that the lithium free surface stability can hardly fulfill or even will exceed this design requirement. Other effects, like lithium jet thickness variation, have also been observed and predicted by calculations. Therefore, hydrodynamical stability of the lithium jet is a major issue and the possible occurrences that could affect it must be examined. To look into these problems, a simulation of the target area has been carried out by means of a CFX 5.7 code calculation. RANS (Reynolds-Averaged Navier Stokes) CFD codes are a very useful tool to supply information of main flow parameters, but there is the necessity to validate the models supporting the results by experimental data. In addition, owing to the uncertainties associated with modelling the free surface of liquid metal with the available turbulent approaches, efforts have been devoted to support the results by means of model assessment. The behaviour of the free surface and lithium jet thickness has been studied considering the liquid fraction volume as a first rough indicator of the

  15. Overview of the system alone and system/CFD coupled calculations of the PHENIX Natural Circulation Test within the THINS project

    Energy Technology Data Exchange (ETDEWEB)

    Pialla, David, E-mail: david.pialla@cea.fr [Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), DEN/DM2S/STMF, 17 rue des martyrs, 38054 Grenoble Cedex 9 (France); Tenchine, Denis [Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), DEN/DM2S/STMF, 17 rue des martyrs, 38054 Grenoble Cedex 9 (France); Li, Simon [Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), DEN/DM2S/STMF, 91191 Gif-sur-Yvette Cedex (France); Gauthe, Paul; Vasile, Alfredo [Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), DEN/DER/SESI, 13108 Saint Paul Lez Durance Cedex (France); Baviere, Roland; Tauveron, Nicolas; Perdu, Fabien [Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), DEN/DM2S/STMF, 17 rue des martyrs, 38054 Grenoble Cedex 9 (France); Maas, Ludovic; Cocheme, François [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN/SEMIA/BAST, B.P. 17, 92262 Fontenay-aux-Roses Cedex (France); Huber, Klaus; Cheng, Xu [Karlsruhe Institute of Technology (KIT), Institute of Fusion and Reactor Technology (IFRT), Kaiserstraße 12, Building 07.08, 76131 Karlsruhe (Germany)

    2015-08-15

    Highlights: • The PHENIX natural convection test performed during the end of life tests program. • The calculation with system codes and theirs limits. • The calculation with coupling CFD and system code, which allows better prediction. • The tasks of code validation have been done in the frame of the THINS project. - Abstract: The PHENIX sodium cooled fast reactor started operation in 1973 and was shut down in 2009. Before decommissioning, an ultimate test program was designed and performed to provide valuable data for the development of future sodium cooled fast reactors, as the so-called Astrid prototype in France. Among these ultimate tests, a thermal-hydraulic Natural Convection Test (NCT) was set-up in June 2009. Starting from a reduced power state of 120 MWt, the NCT consists of a loss of the heat sink combined with a reactor scram and a primary pumps trip leading to stabilized natural circulation in the primary sodium system. The thermal-hydraulics innovative system project (THINS project), sponsored by the European Community in the frame of the 7th FP has selected this transient for validation of both stand-alone system code simulations and coupled simulations using system and CFD codes. Participants from three organizations (CEA, IRSN and KIT) have addressed this transient using different system codes (CATHARE, DYN2B and ATHLET) and CFD codes (TRIO-U and OPEN FOAM). The present paper depicts the different modeling approaches, methodologies and compares the numerical results with the available experimental data. Finally, the main lessons learned from the work performed within the THINS project on the PHENIX NCT with respect to code development and validation are summarized.

  16. Handbook for the calculation of reactor protections; Formulaire sur le calcul de la protection des reacteurs

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1963-07-01

    This note constitutes the first edition of a Handbook for the calculation of reactor protections. This handbook makes it possible to calculate simply the different neutron and gamma fluxes and consequently, to fix the minimum quantities of materials necessary under general safety conditions both for the personnel and for the installations. It contains a certain amount of nuclear data, calculation methods, and constants corresponding to the present state of our knowledge. (authors) [French] Cette note constitue la premiere edition du 'Formulaire sur le calcul de la protection des reacteurs'. Ce formulaire permet de calculer de facon simple les difterents flux de neutrons et de gamma et, par suite, de fixer les quantites minima de materiaux a utiliser pour que les conditions generales de securite soient respectees, tant pour le personnel que pour les installations. Il contient un certain nombre de donnees nucleaires, de methodes de calcul et de constantes correspondant a l'etat actuel de nos connaissances. (auteurs)

  17. CFD and thermal analysis applications at General Motors

    International Nuclear Information System (INIS)

    Johnson, J.P.

    2002-01-01

    The presentation will include a brief history of the growth of CFD and thermal analysis in GM's vehicle program divisions. Its relationship to the underlying computer infrastructure will be sketched. Application results will be presented for calculations in aerodynamics, flow through heat exchangers, engine compartment thermal studies, HVAC systems and others. Current technical challenges will be outlined including grid generation, turbulence modeling, heat transfer, and solution algorithms. The introduction of CFD and heat transfer results into Virtual Vehicle Reviews, and its potential impact on a company's CAE infrastructure will be noted. Finally, some broad comments will be made on the management of CFD and heat transfer technology across a global corporate enterprise. (author)

  18. Coil protection calculator for TFTR

    International Nuclear Information System (INIS)

    Marsala, R.J.; Lawson, J.E.; Persing, R.G.; Senko, T.R.; Woolley, R.D.

    1989-01-01

    A new coil protection system (CPS) is being developed to replace the existing TFTR magnetic coil fault detector. The existing fault detector sacrifices TFTR operating capability for simplicity. The new CPS, when installed in October of 1988, will permit operation up to the actual coil stress limits parameters in real-time. The computation will be done in a microprocessor based Coil Protection Calculator (CPC) currently under construction at PPL. THe new CPC will allow TFTR to operate with higher plasma currents and will permit the optimization of pulse repetition rates. The CPC will provide real-time estimates of critical coil and bus temperatures and stresses based on real-time redundant measurements of coil currents, coil cooling water inlet temperature, and plasma current. The critical parameter calculations are compared to prespecified limits. If these limits are reached or exceeded, protection action will be initiated to a hard wired control system (HCS), which will shut down the power supplies. The CPC consists of a redundant VME based microprocessor system which will sample all input data and compute all stress quantities every ten milliseconds. Thermal calculations will be approximated every 10ms with an exact solution occurring every second. The CPC features continuous cross-checking of redundant input signal, automatic detection of internal failure modes, monitoring and recording of calculated results, and a quick, functional verification of performance via an internal test system. (author)

  19. CFD-based design load analysis of 5MW offshore wind turbine

    Science.gov (United States)

    Tran, T. T.; Ryu, G. J.; Kim, Y. H.; Kim, D. H.

    2012-11-01

    The structure and aerodynamic loads acting on NREL 5MW reference wind turbine blade are calculated and analyzed based on advanced Computational Fluid Dynamics (CFD) and unsteady Blade Element Momentum (BEM). A detailed examination of the six force components has been carried out (three force components and three moment components). Structure load (gravity and inertia load) and aerodynamic load have been obtained by additional structural calculations (CFD or BEM, respectively,). In CFD method, the Reynolds Average Navier-Stokes approach was applied to solve the continuity equation of mass conservation and momentum balance so that the complex flow around wind turbines was modeled. Written in C programming language, a User Defined Function (UDF) code which defines transient velocity profile according to the Extreme Operating Gust condition was compiled into commercial FLUENT package. Furthermore, the unsteady BEM with 3D stall model has also adopted to investigate load components on wind turbine rotor. The present study introduces a comparison between advanced CFD and unsteady BEM for determining load on wind turbine rotor. Results indicate that there are good agreements between both present methods. It is importantly shown that six load components on wind turbine rotor is significant effect under Extreme Operating Gust (EOG) condition. Using advanced CFD and additional structural calculations, this study has succeeded to construct accuracy numerical methodology to estimate total load of wind turbine that compose of aerodynamic load and structure load.

  20. Modelling of nonhomogeneous atmosphere in NPP containment using lumped-parameter model based on CFD calculations

    International Nuclear Information System (INIS)

    Ivo, Kljenak; Miroslav, Babic; Borut, Mavko

    2007-01-01

    The possibility of simulating adequately the flow circulation within a nuclear power plant containment using a lumped-parameter code is considered. An experiment on atmosphere mixing and stratification, which was performed in the containment experimental facility TOSQAN at IRSN (Institute of Radioprotection and Nuclear Safety) in Saclay (France), was simulated with the CFD (Computational Fluid Dynamics) code CFX4 and the lumped-parameter code CONTAIN. During some phases of the experiment, steady states were achieved by keeping the boundary conditions constant. Two steady states during which natural convection was the dominant gas flow mechanism were simulated independently. The nodalization of the lumped-parameter model was based on the flow pattern, simulated with the CFD code. The simulation with the lumped-parameter code predicted basically the same flow circulation patterns within the experimental vessel as the simulation with the CFD code did. (authors)

  1. Radiation protection calculations for diagnostic medical equipment

    International Nuclear Information System (INIS)

    Klueter, R.

    1992-01-01

    The standards DIN 6812 and DIN 6844 define the radiation protection requirements to be met by biomedical radiography equipment or systems for nuclear medicine. The paper explains the use of a specific computer program for radiation protection calculations. The program offers menu-controlled calculation, with free choice of the relevant nuclides. (DG) [de

  2. CFD simulation on reactor flow mixing phenomena

    International Nuclear Information System (INIS)

    Kwon, T.S.; Kim, K.H.

    2016-01-01

    A pre-test calculation for multi-dimensional flow mixing in a reactor core and downcomer has been studied using a CFD code. To study the effects of Reactor Coolant Pump (RCP) and core zone on the boron mixing behaviors in a lower downcomer and core inlet, a 1/5-scale CFD model of flow mixing test facility for the APR+ reference plant was simulated. The flow paths of the 1/5-scale model were scaled down by the linear scaling method. The aspect ratio (L/D) of all flow paths was preserved to 1. To preserve a dynamic similarity, the ratio of Euler number was also preserved to 1. A single phase water flow at low pressure and temperature conditions was considered in this calculation. The calculation shows that the asymmetric effect driven by RCPs shifted the high velocity field to the failed pump's flow zone. The borated water flow zone at the core inlet was also shifted to the failed RCP side. (author)

  3. CALCULATION OF AIR ION REGIME IN THE CASE OF ARTIFICIAL AIR IONIZATION

    Directory of Open Access Journals (Sweden)

    BILIAIEV M. M.

    2015-10-01

    Full Text Available Purpose. One of the major tasks in the field of labor protection is providing of the necessary qualitative composition of air in the working areas of office and industrial spaces. In order to maintain the necessary air ion level in the air space premises, the artificial ionization of air is used often in the premises. At present in Ukraine analytical model are used for the calculation of air ion regime in premises, influencing on the formation process of air ions concentration field. An alternative solution is the use of CFD models, developing including the air jets aerodynamics in the premise, the presence of furniture, equipment, transfer of ions under an electric field, and other physical factors, determining intensity and shape of air ions concentration field in the premise. Methodology. Influence of air flow was taken into account in the development of CFD models for calculation of air ion regime in the apartment, caused by operation of ventilation, diffusion, electric field impact, as well as the interaction of different polarity ions with each other, and their interaction with dust particles. The proposed model of calculation of air ion regime in premises based on the use of aerodynamics, electrostatics and mass transfer levels. This model allows operatively to calculate air ions concentration field with the influence of the walls, floor, ceiling and obstacles on the process of air ions dispersion, the specific location of different polarity ions emission and their interaction in the premise and work areas in conditions of artificial air ionization. Results. The calculated data were obtained and on their base could be estimated the concentration of air ion anywhere in the premise with artificial air ionization. Ions concentration field, being calculated using this CFD model, as concentration field isolines is presented. Originality. The results of the air ion regime calculation in the premise are presented, based on numerical 2D CFD model

  4. Location and sizing of a plant stack: Design study using CFD

    International Nuclear Information System (INIS)

    Petrangeli, Gianni

    2011-01-01

    Highlights: → The paper is a test of applicability of CFD Codes to a nuclear plant stack. → Six cases are studied and comparison is made with common methods. → A comparison with field test data is made. → The study shows that CFD Codes are adequate even in presence of complicated building arrangements. - Abstract: The effect of the presence of a stack on the ground level concentration of emissions near the plant is to significantly decrease the concentrations (in practical cases of interest, by a factor of 5-10), while the presence of nearby plant buildings is to partly eliminate this beneficial effect due to the effect of the building wake. The author of this paper believes that the practical methods currently used for the evaluation of ground concentrations in these cases deserve some improvement. One line of development here suggested is the use of Computer Fluid Dynamics (CFD) codes. The author believes that presently available Code Packages in this field are sufficiently accurate. A number of case studies are presented in this paper, with the aim of encouraging the use of these rather simple methods of study. Moreover, a comparison of calculation results with a field test results confirms also the quantitative reliability of the calculation method here proposed. The main conclusions of this exercise could be the following: -The use of CFD Computer Codes seems suitable for atmospheric dispersion calculations of interest to the nuclear plant designer and safety analyst; in particular, for design studies aimed at the definition of nuclear plant and stack arrangements, the result of this exercise seem to indicate that the methods here used are completely suitable for the comparison of various solutions. -The use of CFD codes may avoid wrong decisions, like the elimination of a stack in the design of a nuclear plant; excessive and detrimental over-conservatism can also be avoided. -When adequate guidance is provided, as this paper attempts to do (), the CFD

  5. Calculation of fuel element temperature TRIGA 2000 reactor in sipping test tubes using CFD

    International Nuclear Information System (INIS)

    Sudjatmi KA

    2013-01-01

    It has been calculated the fuel element temperature in the sipping test of Bandung TRIGA 2000 reactor. The calculation needs to be done to ascertain that the fuel element temperatures are below or at the limit of the allowable temperature fuel elements during reactor operation. ensuring that the implementation of the test by using this device, the temperature is still within safety limits. The calculation is done by making a model sipping test tubes containing a fuel element surrounded by 9 fuel elements. according to the position sipping test tubes in the reactor core. by using Gambit. Dimensional model adapted to the dimensions of the tube and the fuel element in the reactor core of Bandung TRIGA 2000 reactor. Sipping test Operation for each fuel element performed for 30 minutes at 300 kW power. Calculations were performed using CFD software and as input adjusted parameters of TRIGA 2000 reactor. Simulations carried out on the operation of the 30, 60, 90, 120, 150, 180 and 210 minutes. The calculation result shows that the temperature of the fuel in tubes sipping test of 236.06 °C, while the temperature of the wall is 87.58 °C. The maximum temperature in the fuel center of TRIGA 2000 reactor in normal operation is 650 °C. and the boiling is not allowed in the reactor. So it can be concluded that the operation of the sipping test device are is very safe because the fuel center temperature is below the temperature limits the allowable fuel under normal operating conditions as well as the fuel element wall temperature is below the boiling temperature of water. (author)

  6. CFD-model of the mass transfer in the vertical settler

    Directory of Open Access Journals (Sweden)

    E. K. Nagornaya

    2013-02-01

    Full Text Available Purpose. Nowadays the mathematical models of the secondary settlers are intensively developed. As a rule the engineers use the 0-D models or 1-D models to design settlers. But these models do not take into account the hydrodynamics process inside the settler and its geometrical form. That is why the CFD-models based on Navier - Stokes equations are not widely used in practice now. The use of CFD-models based on Navier - Stokes equations needs to incorporate very refine grid. It is very actually now to develop the CFD-models which permit to take into account the geometrical form of the settler, the most important physical processes and needs small computer time for calculation. That is why the development of the 2-D numerical model for the investigation of the waste waters transfer in the vertical settlers which permits to take into account the geometrical form and the constructive features of the settler is essential. Methodology. The finite - difference schemes are applied. Findings. The new 2-D-CFD-model was developed, which permits to perform the CFD investigation of the vertical settler. This model takes into account the geometrical form of the settler, the central pipe inside it and others peculiarities. The method of «porosity technique» is used to create the geometrical form of the settler in the numerical model. This technique permits to build any geometrical form of the settler for CFD investigation. Originality. Making of CFD-model which permits on the one hand to take into account the geometrical form of the settler, basic physical processes of mass transfer in construction and on the other hand requiring the low time cost in order to obtain results. Practical value. CFD-model is designed and code which is constructed on its basis allows at low cost of computer time and about the same as in the calculation of the 1-D model to solve complex multiparameter problems that arise during the design of vertical settlers with their shape and

  7. Test and validation of CFD codes for the simulation of accident-typical phenomena in the reactor containment; Erprobung und Validierung von CFD-Codes fuer die Simulation von unfalltypischen Phaenomenen im Sicherheitseinschluss

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, Berthold; Stewering, Joern; Sonnenkalb, Martin

    2014-03-15

    CFD (Computational Fluid Dynamic) simulation techniques have a growing relevance for the simulation and assessment of accidents in nuclear reactor containments. Some fluid dynamic problems like the calculation of the flow resistances in a complex geometry, turbulence calculations or the calculation of deflagrations could only be solved exactly for very simple cases. These fluid dynamic problems could not be represented by lumped parameter models and must be approximated numerically. Therefore CFD techniques are discussed by a growing international community in conferences like the CFD4NRS-conference. Also the number of articles with a CFD topic is increasing in professional journals like Nuclear Engineering and Design. CFD tools like GASFLOW or GOTHIC are already in use in European nuclear site licensing processes for future nuclear power plants like EPR or AP1000 and the results of these CFD tools are accepted by the authorities. For these reasons it seems to be necessary to build up national competences in the field of CFD techniques and it is important to validate and assess the existing CFD tools. GRS continues the work for the validation and assessment of CFD codes for the simulation of accident scenarios in a nuclear reactor containment within the framework of the BMWi sponsored project RS1500. The focus of this report is on the following topics: - Further validation of condensation models from GRS, FZJ and ANSYS and development of a new condensate model. - Validation of a new turbulence model which was developed by the University of Stuttgart in cooperation with ANSYS. - The formation and dissolution of light gas stratifications are analyzed by large scale experiments. These experiments were simulated by GRS. - The AREVA correlations for hydrogen recombiners (PARs) could be improved by GRS after the analysis of experimental data. Relevant experiments were simulated with this improved recombiner correlation. - Analyses on the simulation of H{sub 2

  8. Modelling of nonhomogeneous atmosphere in NPP containment using lumped-parameter model based on CFD calculations

    International Nuclear Information System (INIS)

    Kljenak, I.; Mavko, B.; Babic, M.

    2005-01-01

    Full text of publication follows: The modelling and simulation of atmosphere mixing and stratification in nuclear power plant containments is a topic, which is currently being intensely investigated. With the increase of computer power, it has now become possible to model these phenomena with a local instantaneous description, using so-called Computational Fluid Dynamics (CFD) codes. However, calculations with these codes still take relatively long times. An alternative faster approach, which is also being applied, is to model nonhomogeneous atmosphere with lumped-parameter codes by dividing larger control volumes into smaller volumes, in which conditions are modelled as homogeneous. The flow between smaller volumes is modelled using one-dimensional approaches, which includes the prescription of flow loss coefficients. However, some authors have questioned this approach, as it appears that atmosphere stratification may sometimes be well simulated only by adjusting flow loss coefficients to adequate 'artificial' values that are case-dependent. To start the resolution of this issue, a modelling of nonhomogeneous atmosphere with a lumped-parameter code is proposed, where the subdivision of a large volume into smaller volumes is based on results of CFD simulations. The basic idea is to use the results of a CFD simulation to define regions, in which the flow velocities have roughly the same direction. These regions are then modelled as control volumes in a lumped-parameter model. In the proposed work, this procedure was applied to a simulation of an experiment of atmosphere mixing and stratification, which was performed in the TOSQAN facility. The facility is located at the Institut de Radioprotection et de Surete Nucleaire (IRSN) in Saclay (France) and consists of a cylindrical vessel (volume: 7 m3), in which gases are injected. In the experiment, which was also proposed for the OECD/NEA International Standard Problem No.47, air was initially present in the vessel, and

  9. Improved core protection calculator system algorithm

    International Nuclear Information System (INIS)

    Yoon, Tae Young; Park, Young Ho; In, Wang Kee; Bae, Jong Sik; Baeg, Seung Yeob

    2009-01-01

    Core Protection Calculator System (CPCS) is a digitized core protection system which provides core protection functions based on two reactor core operation parameters, Departure from Nucleate Boiling Ratio (DNBR) and Local Power Density (LPD). It generates a reactor trip signal when the core condition exceeds the DNBR or LPD design limit. It consists of four independent channels which adapted a two out of four trip logic. CPCS algorithm improvement for the newly designed core protection calculator system, RCOPS (Reactor COre Protection System), is described in this paper. New features include the improvement of DNBR algorithm for thermal margin, the addition of pre trip alarm generation for auxiliary trip function, VOPT (Variable Over Power Trip) prevention during RPCS (Reactor Power Cutback System) actuation and the improvement of CEA (Control Element Assembly) signal checking algorithm. To verify the improved CPCS algorithm, CPCS algorithm verification tests, 'Module Test' and 'Unit Test', would be performed on RCOPS single channel facility. It is expected that the improved CPCS algorithm will increase DNBR margin and enhance the plant availability by reducing unnecessary reactor trips

  10. Natural ventilation of a generic cask under a transport hood - CFD and analytical modelling

    Energy Technology Data Exchange (ETDEWEB)

    Powell, D.; Davies, G.; Tso, C.F. [Arup, London (United Kingdom)

    2004-07-01

    In comparison with finite element simulation for structural and thermal behaviour, the use of computational fluid dynamics technique (hereafter CFD) to analyse, predict and design air and heat flow in package design is relatively novel. Arup has been using CFD techniques to investigate fluid and heat flow, and to use it as a tool to design fluid and heat flow across a broad spectrum of industries for over fifteen years. In order demonstrate the power of the technique and its benefits, the airflow and heat flow characteristics around a transport package during transit under a transport hood has been evaluated using the CFD technique. This paper presents the scenario, the model, the analysis technique and the results of this analysis. Comparison with test results is probably the best way to validate a CFD analysis. In the absence of test results, the analysis was verified by comparison with hand calculation solutions. The scenario as it stands is too complex and hand calculation solution cannot describe the scenario sufficiently. However, hand calculation solutions could be derived for simplified version of the scenario against which CFD analysis of the simplified scenario can be compared. The second half of this paper describes the verification out.

  11. Natural ventilation of a generic cask under a transport hood - CFD and analytical modelling

    International Nuclear Information System (INIS)

    Powell, D.; Davies, G.; Tso, C.F.

    2004-01-01

    In comparison with finite element simulation for structural and thermal behaviour, the use of computational fluid dynamics technique (hereafter CFD) to analyse, predict and design air and heat flow in package design is relatively novel. Arup has been using CFD techniques to investigate fluid and heat flow, and to use it as a tool to design fluid and heat flow across a broad spectrum of industries for over fifteen years. In order demonstrate the power of the technique and its benefits, the airflow and heat flow characteristics around a transport package during transit under a transport hood has been evaluated using the CFD technique. This paper presents the scenario, the model, the analysis technique and the results of this analysis. Comparison with test results is probably the best way to validate a CFD analysis. In the absence of test results, the analysis was verified by comparison with hand calculation solutions. The scenario as it stands is too complex and hand calculation solution cannot describe the scenario sufficiently. However, hand calculation solutions could be derived for simplified version of the scenario against which CFD analysis of the simplified scenario can be compared. The second half of this paper describes the verification out

  12. CFD analysis for offshore systems: validation and applications

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Daniel Fonseca de Carvalho e; Pagot, Paulo Roberto [Centro de Pesquisas da PETROBRAS (CENPES), Rio de janeiro, RJ (Brazil). Gerencia de Tecnologia de Engenharia Oceanica], E-mails: danielfc@petrobras.com.br, pagot@petrobras.com.br

    2011-04-15

    The Ocean Engineering group in the PETROBRAS Research Center develops and applies multidisciplinary simulation tools for several engineering problems mainly related to offshore systems. Recently, there have been many different cases where Computational Fluid Dynamics (CFD) has been successfully employed. This study presents a collection of cases where CFD simulations were validated against experimental data and directly used to facilitate solutions for practical problems. Case 01 calculated the maritime current loads on an FPSO and investigated the influence of appendices such as bilge keels and rudders on the near flow field. Similarly, Case 02 extends this procedure to the identification of wind loads. Case 03 calculates the hydrodynamic forces on a torpedo anchor during its installation. The simulation results coupled with a simplified dynamic model facilitates the directional stability of different torpedo models to be evaluated. A whole FPSO topside geometry is modeled in Case 04, which investigates the flow pattern near the FPSO Helideck. The simulation velocity and turbulence profiles were compared to wind tunnel measurements. These summarized cases show how CFD tools can be advantageously applied to solve many practical problems. All these simulations were performed using ANSYS CFX. (author)

  13. Flow and bed shear stresses in scour protections around a pile in a current

    DEFF Research Database (Denmark)

    Nielsen, Anders Wedel; Liu, Xiaofeng; Sumer, B. Mutlu

    2013-01-01

    on it in an unfavourable manner. Using physical models and 3D computational fluid dynamic (CFD) numerical simulations, the velocity and bed shear stresses are investigated in complex scour protections around mono piles in steady current. In the physical model the scour protections consisted of an upper cover layer...... simulations are capable of calculating the flow velocities when the scour protection is represented by regular arranged spheres, while the turbulence in general is underestimated. The velocity can also be calculated using porous media flow approach, but the accuracy is not as good as for spheres...

  14. CFD and Ventilation Research

    DEFF Research Database (Denmark)

    Li, Y.; Nielsen, Peter V.

    2011-01-01

    There has been a rapid growth of scientific literature on the application of computational fluid dynamics (CFD) in the research of ventilation and indoor air science. With a 1000–10,000 times increase in computer hardware capability in the past 20 years, CFD has become an integral part...... of scientific research and engineering development of complex air distribution and ventilation systems in buildings. This review discusses the major and specific challenges of CFD in terms of turbulence modelling, numerical approximation, and boundary conditions relevant to building ventilation. We emphasize...... the growing need for CFD verification and validation, suggest on-going needs for analytical and experimental methods to support the numerical solutions, and discuss the growing capacity of CFD in opening up new research areas. We suggest that CFD has not become a replacement for experiment and theoretical...

  15. CFD analyses in regulatory practice

    International Nuclear Information System (INIS)

    Bloemeling, F.; Pandazis, P.; Schaffrath, A.

    2012-01-01

    Numerical software is used in nuclear regulatory procedures for many problems in the fields of neutron physics, structural mechanics, thermal hydraulics etc. Among other things, the software is employed in dimensioning and designing systems and components and in simulating transients and accidents. In nuclear technology, analyses of this kind must meet strict requirements. Computational Fluid Dynamics (CFD) codes were developed for computing multidimensional flow processes of the type occurring in reactor cooling systems or in containments. Extensive experience has been accumulated by now in selected single-phase flow phenomena. At the present time, there is a need for development and validation with respect to the simulation of multi-phase and multi-component flows. As insufficient input by the user can lead to faulty results, the validity of the results and an assessment of uncertainties are guaranteed only through consistent application of so-called Best Practice Guidelines. The authors present the possibilities now available to CFD analyses in nuclear regulatory practice. This includes a discussion of the fundamental requirements to be met by numerical software, especially the demands upon computational analysis made by nuclear rules and regulations. In conclusion, 2 examples are presented of applications of CFD analysis to nuclear problems: Determining deboration in the condenser reflux mode of operation, and protection of the reactor pressure vessel (RPV) against brittle failure. (orig.)

  16. Proceedings of the workshop on Benchmarking of CFD Codes for Application to Nuclear Reactor Safety (CFD4NRS)

    International Nuclear Information System (INIS)

    2007-01-01

    -film/wire anemometry, particle image velocimetry, laser induced fluorescence, etc. A particular point of scrutiny for papers in this category was whether an assessment of error bounds and measurement uncertainties was included. There were 98 registered participants to the workshop to hear 5 invited talks and 39 technical papers. It was pointed out that 2/3 of the papers accepted for CFD4NRS were concerned with single-phase calculations and experiments, while 1/3 were dedicated to multi-phase issues. The ratio probably reflects the degree of maturity of CFD in the respective areas, but nonetheless suggests a growing acknowledgement of the role of multi-phase CFD in nuclear NRS issues. Clear recommendations to come out of the workshop for the continuing use of CFD methods in NRS issues are listed below: - Best Practice Guidelines should be followed as far as practical to ensure that CFD simulation results are free of numerical errors, and that the physical models employed are well validated against data appropriate to the flow regimes and physical phenomena being investigated. - Experimental data used for code validation should include estimates of measurement uncertainties, and should include detailed information concerning initial and boundary conditions. - Experimenters involved in producing data for validating CFD models and/or applications should collaborate actively with CFD practitioners in advance of setting up their instrumentation. This interface is vital in ensuring that the information needed to set up the CFD simulation will actually be available, the selection of 'target variables' (i.e. the most significant measurements against which to compare code predictions) is optimal, and the frequency of data acquisition is appropriate to the time-scale(s) of significant fluid-dynamic/heat-transfer/phase-exchange events. - This workshop proved to be a very valuable means to assess the status of CFD code validation and application

  17. Numerical modelling of pressure suppression pools with CFD and FEM codes

    Energy Technology Data Exchange (ETDEWEB)

    Paettikangas, T.; Niemi, J.; Timperi, A. (VTT Technical Research Centre of Finland (Finland))

    2011-06-15

    Experiments on large-break loss-of-coolant accident for BWR is modeled with computational fluid (CFD) dynamics and finite element calculations. In the CFD calculations, the direct-contact condensation in the pressure suppression pool is studied. The heat transfer in the liquid phase is modeled with the Hughes-Duffey correlation based on the surface renewal model. The heat transfer is proportional to the square root of the turbulence kinetic energy. The condensation models are implemented with user-defined functions in the Euler-Euler two-phase model of the Fluent 12.1 CFD code. The rapid collapse of a large steam bubble and the resulting pressure source is studied analytically and numerically. Pressure source obtained from simplified calculations is used for studying the structural effects and FSI in a realistic BWR containment. The collapse results in volume acceleration, which induces pressure loads on the pool walls. In the case of a spherical bubble, the velocity term of the volume acceleration is responsible of the largest pressure load. As the amount of air in the bubble is decreased, the peak pressure increases. However, when the water compressibility is accounted for, the finite speed of sound becomes a limiting factor. (Author)

  18. SDI CFD MODELING ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.

    2011-05-05

    The Savannah River Remediation (SRR) Organization requested that Savannah River National Laboratory (SRNL) develop a Computational Fluid Dynamics (CFD) method to mix and blend the miscible contents of the blend tanks to ensure the contents are properly blended before they are transferred from the blend tank; such as, Tank 50H, to the Salt Waste Processing Facility (SWPF) feed tank. The work described here consists of two modeling areas. They are the mixing modeling analysis during miscible liquid blending operation, and the flow pattern analysis during transfer operation of the blended liquid. The transient CFD governing equations consisting of three momentum equations, one mass balance, two turbulence transport equations for kinetic energy and dissipation rate, and one species transport were solved by an iterative technique until the species concentrations of tank fluid were in equilibrium. The steady-state flow solutions for the entire tank fluid were used for flow pattern analysis, for velocity scaling analysis, and the initial conditions for transient blending calculations. A series of the modeling calculations were performed to estimate the blending times for various jet flow conditions, and to investigate the impact of the cooling coils on the blending time of the tank contents. The modeling results were benchmarked against the pilot scale test results. All of the flow and mixing models were performed with the nozzles installed at the mid-elevation, and parallel to the tank wall. From the CFD modeling calculations, the main results are summarized as follows: (1) The benchmark analyses for the CFD flow velocity and blending models demonstrate their consistency with Engineering Development Laboratory (EDL) and literature test results in terms of local velocity measurements and experimental observations. Thus, an application of the established criterion to SRS full scale tank will provide a better, physically-based estimate of the required mixing time, and

  19. Validation of CFD predictions using process data obtained from flow through an industrial control valve

    International Nuclear Information System (INIS)

    Green, J; Mishra, R; Charlton, M; Owen, R

    2012-01-01

    This study uses the experimental flow test data to validate CFD simulations for a complex control valve trim. In both the simulation and the experimental flow test the capacity of the trim (Cv) is calculated in order to test the ability of CFD software to provide a design tool for these trims. While CFD tests produced results for the capacity which were consistent across a series of five different simulations, it differed from the experimental flow data by nearly 25%. This indicates that CFD simulations need to be properly calibrated before being used in designing complex valve trims.

  20. CFD simulation on condensation inside a Hybrid SIT

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Byong Guk; Ryu, Sung Uk; Kim, Seok; Euh, Dong Jin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The concept of Hybrid Safety Injection Tank system (Hybrid SIT) was proposed by Korea Atomic Energy Research Institute (KAERI) aiming at Advanced Power Reactor Plus. The main advantage of the system is the ready injection of coolant into the reactor coolant system at high pressure. In this paper, a CFD simulation is conducted as a preliminary study. In Hybrid SITs, condensation inside the tank affects its pressure rise and injection time. In an attempt to explore the condensation in detail, we manufactured a dedicated experimental facility for visualization of condensation-induced thermal mixing and conducted a preliminary CFD simulation. Its condensation models were validated first and then computational domain was constructed. The water region was modeled as a solid for stable calculation. The CFD results gave less condensation and excessive pressurization because of lack of steam penetration into the water. In the future, the water region will be modeled as liquid using a VOF model.

  1. Dicty_cDB: CFD492 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available CF (Link to library) CFD492 (Link to dictyBase) - - - Contig-U10808-1 CFD492P (Link to Original site) CFD492...F 583 CFD492Z 527 CFD492P 1110 - - Show CFD492 Library CF (Link to library) Clone ID CFD492...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/CF/CFD4-D/CFD492Q.Seq.d/ Representative seq. ID CFD492...P (Link to Original site) Representative DNA sequence >CFD492 (CFD492Q) /CSM/CF/CFD4-D/CFD492...omology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value CFD492 (CFD492

  2. CFD evaluation of hydrogen risk mitigation measures in a VVER-440/213 containment

    Energy Technology Data Exchange (ETDEWEB)

    Heitsch, Matthias, E-mail: Matthias.Heitsch@ec.europa.e [Institute for Energy, Joint Research Centre, PO Box 2, 1755 ZG Petten (Netherlands); Huhtanen, Risto [VTT Technical Research Centre of Finland, PO Box 1000, FI-02044 VTT (Finland); Techy, Zsolt [VEIKI Institute for Electric Power Research Co., PO Box 80, H-1251 Budapest (Hungary); Fry, Chris [Serco, Winfrith Technology Centre, Dorchester, Dorset DT2 8DH (United Kingdom); Kostka, Pal [VEIKI Institute for Electric Power Research Co., PO Box 80, H-1251 Budapest (Hungary); Niemi, Jarto [VTT Technical Research Centre of Finland, PO Box 1000, FI-02044 VTT (Finland); Schramm, Berthold [Gesellschaft fuer Anlagen- und Reaktorsicherheit, GRS mbH, Schwertnergasse 1, 50667 Koeln (Germany)

    2010-02-15

    In the PHARE project 'Hydrogen Management for the VVER440/213' (HU2002/000-632-04-01), CFD (Computational Fluid Dynamics) calculations using GASFLOW, FLUENT and CFX were performed for the Paks NPP (Nuclear Power Plant), modelling a defined severe accident scenario which involves the release of hydrogen. The purpose of this work is to demonstrate that CFD codes can be used to model gas movement inside a containment during a severe accident. With growing experience in performing such analyses, the results encourage the use of CFD in assessing the risk of losing containment integrity as a result of hydrogen deflagrations. As an effective mitigation measure in such a situation, the implementation of catalytic recombiners is planned in the Paks NPP. In order to support these plans both unmitigated and recombiner-mitigated simulations were performed. These are described and selected results are compared. The codes CFX and FLUENT needed refinement to their models of wall and bulk steam condensation in order to be able to fully simulate the severe accident under consideration. Several CFD codes were used in parallel to model the same accident scenario in order to reduce uncertainties in the results. Previously it was considered impractical to use CFD codes to simulate a full containment subject to a severe accident extending over many hours. This was because of the expected prohibitive computing times and missing physical capabilities of the codes. This work demonstrates that, because of developments in the capabilities of CFD codes and improvements in computer power, these calculations have now become feasible.

  3. A novel methodology for interpreting air quality measurements from urban streets using CFD modelling

    Science.gov (United States)

    Solazzo, Efisio; Vardoulakis, Sotiris; Cai, Xiaoming

    2011-09-01

    In this study, a novel computational fluid dynamics (CFD) based methodology has been developed to interpret long-term averaged measurements of pollutant concentrations collected at roadside locations. The methodology is applied to the analysis of pollutant dispersion in Stratford Road (SR), a busy street canyon in Birmingham (UK), where a one-year sampling campaign was carried out between August 2005 and July 2006. Firstly, a number of dispersion scenarios are defined by combining sets of synoptic wind velocity and direction. Assuming neutral atmospheric stability, CFD simulations are conducted for all the scenarios, by applying the standard k-ɛ turbulence model, with the aim of creating a database of normalised pollutant concentrations at specific locations within the street. Modelled concentration for all wind scenarios were compared with hourly observed NO x data. In order to compare with long-term averaged measurements, a weighted average of the CFD-calculated concentration fields was derived, with the weighting coefficients being proportional to the frequency of each scenario observed during the examined period (either monthly or annually). In summary the methodology consists of (i) identifying the main dispersion scenarios for the street based on wind speed and directions data, (ii) creating a database of CFD-calculated concentration fields for the identified dispersion scenarios, and (iii) combining the CFD results based on the frequency of occurrence of each dispersion scenario during the examined period. The methodology has been applied to calculate monthly and annually averaged benzene concentration at several locations within the street canyon so that a direct comparison with observations could be made. The results of this study indicate that, within the simplifying assumption of non-buoyant flow, CFD modelling can aid understanding of long-term air quality measurements, and help assessing the representativeness of monitoring locations for population

  4. Numerical modelling in building thermo-aeraulics: from CFD modelling to an hybrid finite volume / zonal approach; Modelisation numerique de la thermoaeraulique du batiment: des modeles CFD a une approche hybride volumes finis / zonale

    Energy Technology Data Exchange (ETDEWEB)

    Bellivier, A.

    2004-05-15

    For 3D modelling of thermo-aeraulics in building using field codes, it is necessary to reduce the computing time in order to model increasingly larger volumes. The solution suggested in this study is to couple two modelling: a zonal approach and a CFD approach. The first part of the work that was carried out is the setting of a simplified CFD modelling. We propose rules for use of coarse grids, a constant effective viscosity law and adapted coefficients for heat exchange in the framework of building thermo-aeraulics. The second part of this work concerns the creation of fluid Macro-Elements and their coupling with a calculation of CFD finite volume type. Depending on the boundary conditions of the problem, a local description of the driving flow is proposed via the installation and use of semi-empirical evolution laws. The Macro-Elements is then inserted in CFD computation: the values of velocity calculated by the evolution laws are imposed on the CFD cells corresponding to the Macro-Element. We use these two approaches on five cases representative of thermo-aeraulics in buildings. The results are compared with experimental data and with traditional RANS simulations. We highlight the significant gain of time that our approach allows while preserving a good quality of numerical results. (author)

  5. Eleventh annual conference of the CFD Society of Canada (CFD 2003). Proceedings

    International Nuclear Information System (INIS)

    Ollivier-Gooch, C.

    2003-01-01

    The Eleventh Annual Conference of the CFD Society of Canada, CFD 2003, was held in Vancouver, British Columbia from May 28-30, 2003. The conference was attended by 125 delegates from twelve countries. In addition to traditional CFD applications in vehicle aerodynamics and turbulent flow, the conference also showcased a number of less traditional application areas, including fuel cells, biofluids, multi-phase flows, and flows in porous media

  6. The extensive international use of commercial computational fluid dynamics (CFD) codes

    International Nuclear Information System (INIS)

    Hartmut Wider

    2005-01-01

    What are the main reasons for the extensive international success of commercial CFD codes? This is due to their ability to calculate the fine structures of the investigated processes due to their versatility, their numerical stability and that they can guarantee the proper solution in most cases. This was made possible by the constantly increasing computer power at an ever more affordable prize. Furthermore it is much more efficient to have researchers use a CFD code rather than to develop a similar code system due to the time consuming nature of this activity and the high probability of hidden coding errors. The centralized development and upgrading makes these reliable CFD codes possible and affordable. However, the CFD companies' developments are naturally concentrated on the most profitable areas, and thus, if one works in a 'non-priority' field one cannot use them. Moreover, the prize of renting CFD codes, applications to complex systems such as whole nuclear reactors and the need to teach students gives the development of self-made codes still plenty of room. But CFD codes can model detailed aspects of large systems and subroutines generated by users can be added. Since there are only a few heavily used CFD codes such as FLUENT, STAR-CD, ANSYS CFX, these are used in many countries. Also international training courses are given and the news bulletins of these codes help to spread the news on further developments. A larger number of international codes would increase the competition but would at the same time make it harder to select the most appropriate CFD code for a given problem. Examples will be presented of uses of CFD codes as more detailed system codes for the decay heat removal from reactors, the application to aerosol physics and the application to heavy metal fluids using different turbulence models. (author)

  7. Practical use of CFD for air conditioning duct and defroster designing; Kucho duct defroster no CFD sekkei katsuyo

    Energy Technology Data Exchange (ETDEWEB)

    Okumura, K [Daihatsu Motor Co. Ltd., Osaka (Japan)

    1997-10-01

    The automobile industry have made effort to shorten the development period. Recently CFD (Computational Fluid Dynamics) on initial design stage becomes use for improvement of development efficiency. Although the practical guidepost (computed examples) for air conditioning duct and defroster are a little reported. This report presents how to optimize and standardize the calculational methods, calculational grid, boundary conditions for air conditioning duct and defroster nozzle in the practical use. Also we tried the discontinuous interface grid and the solution adaptive method. 2 refs., 17 figs.

  8. Development of 2-d cfd code

    International Nuclear Information System (INIS)

    Mirza, S.A.

    1999-01-01

    In the present study, a two-dimensional computer code has been developed in FORTRAN using CFD technique, which is basically a numerical scheme. This computer code solves the Navier Stokes equations and continuity equation to find out the velocity and pressure fields within a given domain. This analysis has been done for the developed within a square cavity driven by the upper wall which has become a bench mark for testing and comparing the newly developed numerical schemes. Before to handle this task, different one-dimensional cases have been studied by CFD technique and their FORTRAN programs written. The cases studied are Couette flow, Poiseuille flow with and without using symmetric boundary condition. Finally a comparison between CFD results and analytical results has also been made. For the cavity flow the results from the developed code have been obtained for different Reynolds numbers which are finally presented in the form of velocity vectors. The comparison of the developed code results have been made with the results obtained from the share ware version of a commercially available code for Reynolds number of 10.0. The disagreement in the results quantitatively and qualitatively at some grid points of the calculation domain have been discussed and future recommendations in this regard have also been made. (author)

  9. Test and validation of CFD codes for the simulation of accident-typical phenomena in the reactor containment

    International Nuclear Information System (INIS)

    Schramm, Berthold; Stewering, Joern; Sonnenkalb, Martin

    2014-03-01

    CFD (Computational Fluid Dynamic) simulation techniques have a growing relevance for the simulation and assessment of accidents in nuclear reactor containments. Some fluid dynamic problems like the calculation of the flow resistances in a complex geometry, turbulence calculations or the calculation of deflagrations could only be solved exactly for very simple cases. These fluid dynamic problems could not be represented by lumped parameter models and must be approximated numerically. Therefore CFD techniques are discussed by a growing international community in conferences like the CFD4NRS-conference. Also the number of articles with a CFD topic is increasing in professional journals like Nuclear Engineering and Design. CFD tools like GASFLOW or GOTHIC are already in use in European nuclear site licensing processes for future nuclear power plants like EPR or AP1000 and the results of these CFD tools are accepted by the authorities. For these reasons it seems to be necessary to build up national competences in the field of CFD techniques and it is important to validate and assess the existing CFD tools. GRS continues the work for the validation and assessment of CFD codes for the simulation of accident scenarios in a nuclear reactor containment within the framework of the BMWi sponsored project RS1500. The focus of this report is on the following topics: - Further validation of condensation models from GRS, FZJ and ANSYS and development of a new condensate model. - Validation of a new turbulence model which was developed by the University of Stuttgart in cooperation with ANSYS. - The formation and dissolution of light gas stratifications are analyzed by large scale experiments. These experiments were simulated by GRS. - The AREVA correlations for hydrogen recombiners (PARs) could be improved by GRS after the analysis of experimental data. Relevant experiments were simulated with this improved recombiner correlation. - Analyses on the simulation of H_2 deflagration

  10. CFD Calculations of the Flow Around a Wind Turbine Nacelle

    International Nuclear Information System (INIS)

    Varela, J.; Bercebal, D.

    1999-01-01

    The purpose of this work is to identify the influence of a MADE AE30 wind turbine nacelle on the site calibration anemometer placed on the upper back of the nacelle by means of flow simulations around the nacelle using FLUENT, a Commercial Computational Fluid Dynamics code (CFD), which provides modeling capabilities for the simulation of wide range laminar and turbulent fluid flow problems. Different 2D and 3D simulations were accomplished in order to estimate the effects of the complex geometry on the flow behavior. The speed up and braking values of the air flow at the anemometer position are presented for different flow conditions. Finally some conclusions about the accuracy of results are mentioned. (Author) 5 refs

  11. CFD Calculations of the Flow Around a Wind Turbine Nacelle

    Energy Technology Data Exchange (ETDEWEB)

    Varela, J.; Bercebal, D. [Ciemat, Madrid (Spain)

    2000-07-01

    The purpose of this work is to identify the influence of a MADE AE30 wind turbine nacelle on the site calibration anemometer placed on the upper back of the nacelle by means of flow simulations around the nacelle using FLUENT, a Commercial Computational Fluid Dynamics code (CFD), which provides modeling capabilities for the simulation of wide range laminar and turbulent fluid flow problems. Different 2D and 3D simulations were accomplished in order to estimate the effects of the complex geometry on the flow behavior. The speed up and braking values of the air flow at the anemometer position are presented for different flow conditions. Finally some conclusions about the accuracy of results are mentioned. (Author) 5 refs.

  12. iCFD: Interpreted Computational Fluid Dynamics - Degeneration of CFD to one-dimensional advection-dispersion models using statistical experimental design - The secondary clarifier.

    Science.gov (United States)

    Guyonvarch, Estelle; Ramin, Elham; Kulahci, Murat; Plósz, Benedek Gy

    2015-10-15

    The present study aims at using statistically designed computational fluid dynamics (CFD) simulations as numerical experiments for the identification of one-dimensional (1-D) advection-dispersion models - computationally light tools, used e.g., as sub-models in systems analysis. The objective is to develop a new 1-D framework, referred to as interpreted CFD (iCFD) models, in which statistical meta-models are used to calculate the pseudo-dispersion coefficient (D) as a function of design and flow boundary conditions. The method - presented in a straightforward and transparent way - is illustrated using the example of a circular secondary settling tank (SST). First, the significant design and flow factors are screened out by applying the statistical method of two-level fractional factorial design of experiments. Second, based on the number of significant factors identified through the factor screening study and system understanding, 50 different sets of design and flow conditions are selected using Latin Hypercube Sampling (LHS). The boundary condition sets are imposed on a 2-D axi-symmetrical CFD simulation model of the SST. In the framework, to degenerate the 2-D model structure, CFD model outputs are approximated by the 1-D model through the calibration of three different model structures for D. Correlation equations for the D parameter then are identified as a function of the selected design and flow boundary conditions (meta-models), and their accuracy is evaluated against D values estimated in each numerical experiment. The evaluation and validation of the iCFD model structure is carried out using scenario simulation results obtained with parameters sampled from the corners of the LHS experimental region. For the studied SST, additional iCFD model development was carried out in terms of (i) assessing different density current sub-models; (ii) implementation of a combined flocculation, hindered, transient and compression settling velocity function; and (iii

  13. CFD Calculation of Internal Natural Convection in the Annulus between Horizontal Concentric Cylinders

    International Nuclear Information System (INIS)

    Francis, N.D. Jr.; Itamura, M.T.; Webb, S.W.; James, D.L.

    2002-01-01

    The objective of this heat transfer and fluid flow study is to assess the ability of a computational fluid dynamics (CFD) code to reproduce the experimental results, numerical simulation results, and heat transfer correlation equations developed in the literature for natural convection heat transfer within the annulus of horizontal concentric cylinders. In the literature, a variety of heat transfer expressions have been developed to compute average equivalent thermal conductivities. However, the expressions have been primarily developed for very small inner and outer cylinder radii and gap-widths. In this comparative study, interest is primarily focused on large gap widths (on the order of half meter or greater) and large radius ratios. From the steady-state CFD analysis it is found that the concentric cylinder models for the larger geometries compare favorably to the results of the Kuehn and Goldstein correlations in the Rayleigh number range of about 10 5 to 10 8 (a range that encompasses the laminar to turbulent transition). For Rayleigh numbers greater than 10 8 , both numerical simulations and experimental data (from the literature) are consistent and result in slightly lower equivalent thermal conductivities than those obtained from the Kuehn and Goldstein correlations

  14. Comparison of a semi-analytic and a CFD model uranium combustion to experimental data

    International Nuclear Information System (INIS)

    Clarksean, R.

    1998-01-01

    Two numerical models were developed and compared for the analysis of uranium combustion and ignition in a furnace. Both a semi-analytical solution and a computational fluid dynamics (CFD) numerical solution were obtained. Prediction of uranium oxidation rates is important for fuel storage applications, fuel processing, and the development of spent fuel metal waste forms. The semi-analytical model was based on heat transfer correlations, a semi-analytical model of flow over a flat surface, and simple radiative heat transfer from the material surface. The CFD model numerically determined the flowfield over the object of interest, calculated the heat and mass transfer to the material of interest, and calculated the radiative heat exchange of the material with the furnace. The semi-analytical model is much less detailed than the CFD model, but yields reasonable results and assists in understanding the physical process. Short computation times allowed the analyst to study numerous scenarios. The CFD model had significantly longer run times, was found to have some physical limitations that were not easily modified, but was better able to yield details of the heat and mass transfer and flow field once code limitations were overcome

  15. Isothermal coarse mixing: experimental and CFD modelling

    International Nuclear Information System (INIS)

    Gilbertson, M.A.; Kenning, D.B.R.; Hall, R.W.

    1992-01-01

    A plane, two-dimensional flow apparatus has been built which uses a jet of solid 6mm diameter balls to model a jet of molten drops falling into a tank of water to study premixing prior to a vapour explosion. Preliminary experiments with unheated stainless steel balls are here compared with computational fluid dynamics (CFD) calculations by the code CHYMES. (6 figures) (Author)

  16. Validation of a CFD analysis model for the calculation of CANDU6 moderator temperature distribution

    International Nuclear Information System (INIS)

    Yoon, Churl; Rhee, Bo Wook; Min, Byung Joo

    2001-01-01

    A validation of a 3D CFD model for predicting local subcooling of moderator in the vicinity of calandria tubes in a CANDU reactor is performed. The small scale moderator experiments performed at Sheridan Park Experimental Laboratory (SPEL) in Ontario, Canada is used for the validation. Also a comparison is made between previous DFD analyses based on 2DMOTH and PHOENICS, and the current model analysis for the same SPEL experiment. For the current model, a set of grid structures for the same geometry as the experimental test section is generated and the momentum, heat and continuity equations are solved by CFX-4.3, a CFD code developed by AEA technology. The matrix of calandria tubes is simplified by the porous media approach. The standard κ-ε turbulence model associated with logarithmic wall treatment and SIMPLEC algorithm on the body fitted grid are used and buoyancy effects are accounted for by the Boussinesq approximation. For the test conditions simulated in this study, the flow pattern identified is a buoyancy-dominated flow, which is generated by the interaction between the dominant buoyancy force by heating and inertial momentum forces by the inlet jets. As a result, the current CFD moderator analysis model predicts the moderator temperature reasonably, and the maximum error against the experimental data is kept at less than 2.0 .deg. C over the whole domain. The simulated velocity field matches with the visualization of SPEL experiments quite well

  17. AP-IO: asynchronous pipeline I/O for hiding periodic output cost in CFD simulation.

    Science.gov (United States)

    Xiaoguang, Ren; Xinhai, Xu

    2014-01-01

    Computational fluid dynamics (CFD) simulation often needs to periodically output intermediate results to files in the form of snapshots for visualization or restart, which seriously impacts the performance. In this paper, we present asynchronous pipeline I/O (AP-IO) optimization scheme for the periodically snapshot output on the basis of asynchronous I/O and CFD application characteristics. In AP-IO, dedicated background I/O processes or threads are in charge of handling the file write in pipeline mode, therefore the write overhead can be hidden with more calculation than classic asynchronous I/O. We design the framework of AP-IO and implement it in OpenFOAM, providing CFD users with a user-friendly interface. Experimental results on the Tianhe-2 supercomputer demonstrate that AP-IO can achieve a good optimization effect for the periodical snapshot output in CFD application, and the effect is especially better for massively parallel CFD simulations, which can reduce the total execution time up to about 40%.

  18. AP-IO: Asynchronous Pipeline I/O for Hiding Periodic Output Cost in CFD Simulation

    Directory of Open Access Journals (Sweden)

    Ren Xiaoguang

    2014-01-01

    Full Text Available Computational fluid dynamics (CFD simulation often needs to periodically output intermediate results to files in the form of snapshots for visualization or restart, which seriously impacts the performance. In this paper, we present asynchronous pipeline I/O (AP-IO optimization scheme for the periodically snapshot output on the basis of asynchronous I/O and CFD application characteristics. In AP-IO, dedicated background I/O processes or threads are in charge of handling the file write in pipeline mode, therefore the write overhead can be hidden with more calculation than classic asynchronous I/O. We design the framework of AP-IO and implement it in OpenFOAM, providing CFD users with a user-friendly interface. Experimental results on the Tianhe-2 supercomputer demonstrate that AP-IO can achieve a good optimization effect for the periodical snapshot output in CFD application, and the effect is especially better for massively parallel CFD simulations, which can reduce the total execution time up to about 40%.

  19. Magnetic resonance imaging and computational fluid dynamics (CFD) simulations of rabbit nasal airflows for the development of hybrid CFD/PBPK models.

    Science.gov (United States)

    Corley, R A; Minard, K R; Kabilan, S; Einstein, D R; Kuprat, A P; Harkema, J R; Kimbell, J S; Gargas, M L; Kinzell, John H

    2009-05-01

    The percentages of total airflows over the nasal respiratory and olfactory epithelium of female rabbits were calculated from computational fluid dynamics (CFD) simulations of steady-state inhalation. These airflow calculations, along with nasal airway geometry determinations, are critical parameters for hybrid CFD/physiologically based pharmacokinetic models that describe the nasal dosimetry of water-soluble or reactive gases and vapors in rabbits. CFD simulations were based upon three-dimensional computational meshes derived from magnetic resonance images of three adult female New Zealand White (NZW) rabbits. In the anterior portion of the nose, the maxillary turbinates of rabbits are considerably more complex than comparable regions in rats, mice, monkeys, or humans. This leads to a greater surface area to volume ratio in this region and thus the potential for increased extraction of water soluble or reactive gases and vapors in the anterior portion of the nose compared to many other species. Although there was considerable interanimal variability in the fine structures of the nasal turbinates and airflows in the anterior portions of the nose, there was remarkable consistency between rabbits in the percentage of total inspired airflows that reached the ethmoid turbinate region (approximately 50%) that is presumably lined with olfactory epithelium. These latter results (airflows reaching the ethmoid turbinate region) were higher than previous published estimates for the male F344 rat (19%) and human (7%). These differences in regional airflows can have significant implications in interspecies extrapolations of nasal dosimetry.

  20. Tenth annual conference of the CFD Society of Canada (CFD 2002). Proceedings

    International Nuclear Information System (INIS)

    Barron, R.M.

    2002-01-01

    The Tenth Annual Conference of the CFD Society of Canada, CFD 2002, was held in Windsor, Ontario from June 9-11, 2002. Contributions and participation were from many countries including Canada, United States, United Kingdom, France, Belgium, Germany, Iran, India, Pakistan, China, Japan, Singapore, Kuwait and Russia. The proceedings are a collection of the papers received covering the spectrum of computational fluid dynamics (CFD) from fundamental advances to improved algorithms to traditional and innovative applications. There is also a special session on automotive applications

  1. CFD Simulations of Soap Separation; CFD-simulering av avsaapning

    Energy Technology Data Exchange (ETDEWEB)

    Birkestad, Per

    2010-07-01

    A part of Vaermeforsk, the 'Skogsindustriella programmet', has identified the possibility to increase the production of tall oil, and hence the competitiveness, in Swedish pulp mills through an increase in the efficiency of the soap separation tanks. Currently, soap is extracted from the black liquor through a sedimentation process where the less dense soap rise to the top of the liquor tank where it is removed through a over-flow ducting at the top of the tank. Vaermeforsk seeks a better understanding of the detailed flow and the separation mechanisms within the liquor tanks and has initiated a study of computational fluid dynamics (CFD) of the tanks. The aim of the study has been threefold; To develop CFD-methods for use in the study of soap separation processes, to investigate the detailed flow within two Swedish liquor tanks and one North American soap skimmer and lastly to develop new design rules for use in future designs of soap separation tanks. The project shows that CFD is a useful tool for the investigation of black liquor and soap flow within a soap separation tank. The CFD simulations of three existing liquor tanks show that the previously used design-rules based on surface loads are inadequate as the actual flow velocities within the tanks are two orders of magnitude larger than those previously used as reference (the surface load). The CFD simulations also show that the black liquor flow, and hence the soap separation, is very sensitive to density variations on the black liquor inlet and temperature variations as small as 1 deg C can significantly affect the liquor flow.

  2. Processes and Procedures for Application of CFD to Nuclear Reactor Safety Analysis

    International Nuclear Information System (INIS)

    Richard W. Johnson; Richard R. Schultz; Patrick J. Roache; Ismail B. Celik; William D. Pointer; Yassin A. Hassan

    2006-01-01

    of the flow and energy transport as applied to nuclear reactor safety. However, it is expected that these practices and procedures will require updating from time to time as research and development affect them or replace them with better procedures. The practices and procedures are categorized into five groups. These are: (1) Code Verification; (2) Code and Calculation Documentation; (3) Reduction of Numerical Error; (4) Quantification of Numerical Uncertainty (Calculation Verification); and (5) Calculation Validation. These five categories have been identified from procedures currently required of CFD simulations such as those required for publication of a paper in the ASME Journal of Fluids Engineering and from the literature such as Roache [1998]. Code verification refers to the demonstration that the equations of fluid and energy transport have been correctly coded in the CFD code. Code and calculation documentation simply means that the equations and their discretizations, etc., and boundary and initial conditions used to pose the fluid flow problem are fully described in available documentation. Reduction of numerical error refers to practices and procedures to lower numerical errors to negligible or very low levels as is reasonably possible (such as avoiding use of first-order discretizations). The quantification of numerical uncertainty is also known as calculation verification. This means that estimates are made of numerical error to allow the characterization of the numerical results with a certain confidence level. Numerical error in this case does not include error due to models such as turbulence models. Calculation validation is the process of comparing simulation results to experimental data to demonstrate level of agreement. Validation does include the effects of modeling errors as well as numerical and experimental errors. A key issue in the validation process of numerical results is the existence of appropriate experimental data to use for

  3. Use of CFD in development of intake ports for diesel engines

    International Nuclear Information System (INIS)

    Alcenius, T.

    2002-01-01

    The design of intake ports for diesel engines is difficult due to the many competing requirements of the cylinder head design. When the concept design is completed, the typical course for verification and optimization of the port is through steady state flow testing. In the past, optimization of the port was considered a 'black art' as the final shape of the port and its performance was tied directly to the experience of the port development engineer. As CFD has been increasingly used to analyze various aspects of engine performance, an obvious area to explore is its use to predict steady state port flow performance prior to fabrication of any test hardware. A study was carried out to evaluate the usefulness of CFD in predicting steady state flow bench results and to provide insight into the fluid mechanics of the port flow to assist in the flow bench development. Port flow testing was carried out on a baseline diesel engine port for a range of valve lifts from zero to just above the maximum valve lift. This experimental test data was used to calculate flow coefficients and swirl ratios (an indicator of mean air motion in the cylinder). Subsequently, CFD models were generated that replicated the flow bench set-up. Three valve lifts across the valve lift range were chosen for the comparison. Results of the analysis were used to calculate flow coefficients and swirl ratios. Computed results were then compared to the experiments to determine their accuracy and a detailed review of the CFD results was conducted to understand the flow in the port. Modifications were made to the port from recommendations made based on the CFD results. The ports were then retested to determine the effectiveness of the recommendations. Finally, the results are discussed as to their meaning and usefulness for design programs. (author)

  4. Development of Geometry Optimization Methodology with In-house CFD code, and Challenge in Applying to Fuel Assembly

    International Nuclear Information System (INIS)

    Jeong, J. H.; Lee, K. L.

    2016-01-01

    The wire spacer has important roles to avoid collisions between adjacent rods, to mitigate a vortex induced vibration, and to enhance convective heat transfer by wire spacer induced secondary flow. Many experimental and numerical works has been conducted to understand the thermal-hydraulics of the wire-wrapped fuel bundles. There has been enormous growth in computing capability. Recently, a huge increase of computer power allows to three-dimensional simulation of thermal-hydraulics of wire-wrapped fuel bundles. In this study, the geometry optimization methodology with RANS based in-house CFD (Computational Fluid Dynamics) code has been successfully developed in air condition. In order to apply the developed methodology to fuel assembly, GGI (General Grid Interface) function is developed for in-house CFD code. Furthermore, three-dimensional flow fields calculated with in-house CFD code are compared with those calculated with general purpose commercial CFD solver, CFX. The geometry optimization methodology with RANS based in-house CFD code has been successfully developed in air condition. In order to apply the developed methodology to fuel assembly, GGI function is developed for in-house CFD code as same as CFX. Even though both analyses are conducted with same computational meshes, numerical error due to GGI function locally occurred in only CFX solver around rod surface and boundary region between inner fluid region and outer fluid region.

  5. Two-phase CFD PTS validation in an extended range of thermohydraulics conditions covered by the COSI experiment

    International Nuclear Information System (INIS)

    Coste, P.; Ortolan, A.

    2014-01-01

    Highlights: • Models for large interfaces in two-phase CFD were developed for PTS. • The COSI experiment is used for NEPTUNE C FD integral validation. • COSI is a PWR cold leg scaled 1/100 for volume. • Fifty runs are calculated, covering a large range of flow configurations. • The CFD predicting capability is analysed using global and local measurements. - Abstract: In the context of the Pressurized Water Reactors (PWR) life duration safety studies, some models were developed to address the Pressurized Thermal Shock (PTS) from the two-phase CFD angle, dealing with interfaces much larger than cells size and with direct contact condensation. Such models were implemented in NEPTUNE C FD, a 3D transient Eulerian two-fluid model. The COSI experiment is used for its integral validation. It represents a cold leg scaled 1/100 for volume and power from a 900 MW PWR under a large range of LOCA PTS conditions. In this study, the CFD is evaluated in the whole range of parameters and flow configurations covered by the experiment. In a first step, a single choice of mesh and CFD models parameters is fixed and justified. In a second step, fifty runs are calculated. The CFD predicting capability is analysed, comparing the liquid temperature and the total condensation rate with the experiment, discussing their dependency on the inlet cold liquid rate, on the liquid level in the cold leg and on the difference between co-current and counter-current runs. It is shown that NEPTUNE C FD 1.0.8 calculates with a fair agreement a large range of flow configurations related to ECCS injection and steam condensation

  6. Comparison of sensor systems designed using multizone, zonal, and CFD data for protection of indoor environments

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y. Lisa; Wen, Jin [Civil, Architectural, and Environmental Engineering, Drexel University, Philadelphia, PA 19104 (United States)

    2010-04-15

    Sensors that detect chemical and biological warfare agents can offer early warning of dangerous contaminants. However, current sensor system design is mostly by intuition and experience rather than by systematic design. To develop a sensor system design methodology, the proper selection of an indoor airflow model is needed. Various indoor airflow models exist in the literature, from complex computational fluid dynamics (CFD) to simpler approaches such as multizone and zonal models. Airflow models provide the contaminant concentration data, to which an optimization method can be applied to design sensor systems. The authors utilized a subzonal modeling approach when using a multizone model and were the first to utilize a zonal model for systematic sensor system design. The objective of the study was to examine whether or not data from a simpler airflow model could be used to design sensor systems capable of performing just as well as those designed using data from more complex CFD models. Three test environments, a small office, a large hall, and an office suite were examined. Results showed that when a unique sensor system design was not needed, sensor systems designed using data from simpler airflow models could perform just as well as those designed using CFD data. Further, only for the small office did the common engineering sensor system design practice of placing a sensor at the exhaust result in sensor system performance that was equivalent to one designed using CFD data. (author)

  7. Validation of a Computational Fluid Dynamics (CFD) Code for Supersonic Axisymmetric Base Flow

    Science.gov (United States)

    Tucker, P. Kevin

    1993-01-01

    The ability to accurately and efficiently calculate the flow structure in the base region of bodies of revolution in supersonic flight is a significant step in CFD code validation for applications ranging from base heating for rockets to drag for protectives. The FDNS code is used to compute such a flow and the results are compared to benchmark quality experimental data. Flowfield calculations are presented for a cylindrical afterbody at M = 2.46 and angle of attack a = O. Grid independent solutions are compared to mean velocity profiles in the separated wake area and downstream of the reattachment point. Additionally, quantities such as turbulent kinetic energy and shear layer growth rates are compared to the data. Finally, the computed base pressures are compared to the measured values. An effort is made to elucidate the role of turbulence models in the flowfield predictions. The level of turbulent eddy viscosity, and its origin, are used to contrast the various turbulence models and compare the results to the experimental data.

  8. Prediction of hydraulic force and momentum on pelton turbine jet deflector based on cfd simulation

    International Nuclear Information System (INIS)

    Popovski, Boro

    2015-01-01

    The numerical simulation of three-dimensional turbulent flow through the jet-distributor, free stream jet and deflector of Pelton Turbine is presented in this work. The calculations are performed using the CFD package Ansys CFX (Navie-Stokes equations and the k-omega SST turbulent model). A traditional definition for calculation of hydraulic forces and momentum on the jet deflector and a method for experimental evaluation are described. The steps for flow modelling, mesh (grid) generation, as well as the results obtained from the numerical simulation of the flow and stress deformation calculations of the jet-deflector are presented. This work corresponds with the actual approach of methods development for flow simulation and calculations of Pelton Turbines. The kinematic and dynamic parameters are calculated based on CFD simulations. The results of the calculations represents reliable tool in the procedure of development and construction of Pelton Turbines. (author)

  9. CFD analysis of linear compressors considering load conditions

    Science.gov (United States)

    Bae, Sanghyun; Oh, Wonsik

    2017-08-01

    This paper is a study on computational fluid dynamics (CFD) analysis of linear compressor considering load conditions. In the conventional CFD analysis of the linear compressor, the load condition was not considered in the behaviour of the piston. In some papers, behaviour of piston is assumed as sinusoidal motion provided by user defined function (UDF). In the reciprocating type compressor, the stroke of the piston is restrained by the rod, while the stroke of the linear compressor is not restrained, and the stroke changes depending on the load condition. The greater the pressure difference between the discharge refrigerant and the suction refrigerant, the more the centre point of the stroke is pushed backward. And the behaviour of the piston is not a complete sine wave. For this reason, when the load condition changes in the CFD analysis of the linear compressor, it may happen that the ANSYS code is changed or unfortunately the modelling is changed. In addition, a separate analysis or calculation is required to find a stroke that meets the load condition, which may contain errors. In this study, the coupled mechanical equations and electrical equations are solved using the UDF, and the behaviour of the piston is solved considering the pressure difference across the piston. Using the above method, the stroke of the piston with respect to the motor specification of the analytical model can be calculated according to the input voltage, and the piston behaviour can be realized considering the thrust amount due to the pressure difference.

  10. CFD Analysis to Calculate the Optimal Air Velocity in Drying Green Tea Process Using Fluidized Bed Dryer

    Science.gov (United States)

    Yohana, Eflita; Nugraha, Afif Prasetya; Diana, Ade Eva; Mahawan, Ilham; Nugroho, Sri

    2018-02-01

    Tea processing is basically distinguished into three types which black tea, green tea, and oolong tea. Green tea is processed by heating and drying the leaves. Green tea factories in Indonesia are generally using the process of drying by panning the leaves. It is more recommended to use the fluidization process to speed up the drying process as the quality of the tea can be maintained. Bubbling fluidization is expected to occur in this research. It is a process of bubbles are formed in the fluidization. The effectiveness of the drying process in a fluidized bed dryer machine needs to be improved by using a CFD simulation method to proof that umf < u < ut, where the average velocity value is limited by the minimum and the maximum velocity of the calculation the experimental data. The minimum and the maximum velocity value of the fluidization is 0.96 m/s and 8.2 m/s. The result of the simulation obtained that the average velocity of the upper bed part is 1.81 m/s. From the results obtained, it can be concluded that the calculation and the simulation data is in accordance with the condition of bubbling fluidization in fluidized bed dryer.

  11. Using of CFD software for setting the location of water stream micro turbines

    Directory of Open Access Journals (Sweden)

    Borsuk Łukasz

    2016-01-01

    Full Text Available The aim of this work was to estimate the efficiency of CFD software in calculating flow velocity magnitude in natural water streams. These kinds of estimations are essential for setting the locations of water stream micro turbines. These devices can be useful to provide electricity in areas remote from power generating facilities or as backup power supply in case of power grid failure. The analysed water stream has length of 100 m and its average slope was approximately 10%. Water velocity varies in the range from 0.5 m3*s−1 to 5 m3*s−1. Additionally, the influence of ground roughness on the stream velocity was also an important factor. Results proved to be satisfactory. In the analysed stream, velocities were in a range which allows the proposed micro turbine to be effective. Calculation grid created by CFD software did not have many areas which may raise doubts. Also, the influence of changes in the ground roughness factor was noticeable. Preliminary CFD simulations allow to estimate where in the stream the micro turbine will be most efficient. On the other hand, despite these calculations, profitability and return on the investment still can be questionable.

  12. The analysis of coolant-velocity distribution in plat-typed fuel element using CFD method for RSG-GAS research reactor

    International Nuclear Information System (INIS)

    Muhammad Subekti; Darwis Isnaini; Endiah Puji Hastuti

    2013-01-01

    The measurement experiment for coolant-velocity distribution in the subchannel of fuel element of RSG-GAS research reactor is difficult to be carried out due to too narrow channel and subchannel placed inside the fuel element. Hence, the calculation is required to predict the coolant-velocity distribution inside subchannel to confirm that the handle presence does not ruin the velocity distribution into every subchannel. This calculation utilizes CFD method, which respect to 3-dimension interior. Moreover, the calculation of coolant-velocity distribution inside subchannel was not ever carried out. The research object is to investigate the distribution of coolant-velocity in plat-typed fuel element using 3-dimension CFD method for RSG-GAS research reactor. This research is required as a part of the development of thermalhydraulic design of fuel element for innovative research reactor as well. The modeling uses ½ model in Gambit software and calculation uses turbulence equation in FLUENT 6.3 software. Calculation result of 3D coolant-velocity in subchannel using CFD method is lower about 4.06 % than 1D calculation result due to 1D calculation obeys handle availability. (author)

  13. Computational fluid dynamics (CFD) using porous media modeling predicts recurrence after coiling of cerebral aneurysms.

    Science.gov (United States)

    Umeda, Yasuyuki; Ishida, Fujimaro; Tsuji, Masanori; Furukawa, Kazuhiro; Shiba, Masato; Yasuda, Ryuta; Toma, Naoki; Sakaida, Hiroshi; Suzuki, Hidenori

    2017-01-01

    This study aimed to predict recurrence after coil embolization of unruptured cerebral aneurysms with computational fluid dynamics (CFD) using porous media modeling (porous media CFD). A total of 37 unruptured cerebral aneurysms treated with coiling were analyzed using follow-up angiograms, simulated CFD prior to coiling (control CFD), and porous media CFD. Coiled aneurysms were classified into stable or recurrence groups according to follow-up angiogram findings. Morphological parameters, coil packing density, and hemodynamic variables were evaluated for their correlations with aneurysmal recurrence. We also calculated residual flow volumes (RFVs), a novel hemodynamic parameter used to quantify the residual aneurysm volume after simulated coiling, which has a mean fluid domain > 1.0 cm/s. Follow-up angiograms showed 24 aneurysms in the stable group and 13 in the recurrence group. Mann-Whitney U test demonstrated that maximum size, dome volume, neck width, neck area, and coil packing density were significantly different between the two groups (P CFD and larger RFVs in the porous media CFD. Multivariate logistic regression analyses demonstrated that RFV was the only independently significant factor (odds ratio, 1.06; 95% confidence interval, 1.01-1.11; P = 0.016). The study findings suggest that RFV collected under porous media modeling predicts the recurrence of coiled aneurysms.

  14. CFD SIMULATION OF AIR ION REGIME IN WORK AREAS AT CONDITION OF ARTIFICIAL AIR IONIZATION

    Directory of Open Access Journals (Sweden)

    M. M. Biliaiev

    2016-02-01

    Full Text Available Purpose. The paper supposes creation of a CFD model for calculating the air ion regime in the premises and in work areas at artificial ionization of the air by the ionizer installation indoors with considering the most important physical factors that influence the formation of ions concentration field. Methodology. The proposed CFD model for calculation of the air ion regime in work areas at artificial ionization of the air by installing ionizer indoors is based on the application of aerodynamics, electrostatics and mass transfer equations. The mass transfer equation takes into account the interaction of different polarities of ions with each other and with the dust particles. The calculation of air flow rate in the room is realized on the basis of the potential flow model by using the Laplace equation for the stream function. Poisson equation for the electric potential is used for calculation of the charged particles drift in an electric field. At the simulation to take into account: 1 influence of the working area geometric characteristics; 2 location of the ventilation holes; 3 placement of furniture and equipment; 4 ventilation regime in the room; 5 presence of obstacles on the ions dispersion process; 6 specific location of dust particles emission and ions of different polarity, and their interaction in the room and in the working zones. Findings. The developed CFD model allows determining the concentration of negative ions in the room and in the area of the human respiratory organs. The distribution of the negative ions concentration is presented in the form of concentration field isolines. Originality. The 2D CFD model for calculating the air ion regime in working areas, providing the ability to determine the ions concentration in a given place in the room was created. The proposed model is developed taking into account: placement of furniture and equipment in the room; geometric characteristics of the room; location of dust emissions

  15. Comprehensive CFD analyses concerning the serious incident occurred in the Paks NPP, Spring 2003

    International Nuclear Information System (INIS)

    Legradi, Gabor; Boros, Ildiko; Aszodi, Attila

    2007-01-01

    removing equipments will work standing on a platform which will be placed into the service shaft just above the surface of the coolant. Therefore protecting the workers against unnecessary personal doses is a very important task. Therefore, the vertical distribution of the contamination in the service shaft was estimated for different operational and incidental scenarios with a wide parameter-study performed with a 3D CFD model. All calculations were performed with different types of CFX codes. (authors)

  16. CFD for Nuclear Reactor Safety Applications (CFD4NRS-4) - Workshop Proceedings

    International Nuclear Information System (INIS)

    2014-01-01

    Following the CFD4NRS workshops held in Garching, Germany (Sept. 2006), Grenoble, France (Sep. 2008) and Washington D.C., USA (Sept. 2010), this Workshop is intended to extend the forum created for numerical analysts and experimentalists to exchange information in the application of CFD and CMFD to NRS issues and in guiding nuclear reactor design thinking. The workshop includes single-phase and multi-phase CFD applications, and offers the opportunity to present new experimental data for CFD validation. More emphasis has been given to the experiments, especially on two-phase flow, for advanced CMFD modelling for which sophisticated measurement techniques are required. Understanding of the physics has been depen before starting numerical analysis. Single-phase and multi-phase CFD simulations with a focus on validation were performed in areas such as: single-phase heat transfer, boiling flows, free-surface flows, direct contact condensation and turbulent mixing. These relate to NRS-relevant issues, such as pressurised thermal shock, critical heat flux, pool heat exchangers, boron dilution, hydrogen distribution in containments, thermal striping, etc. The use of systematic error quantification and the application of BPGs were strongly encouraged. Experiments providing data suitable for CFD or CMFD validation were also presented. These included local measurements using multi-sensor probes, laser-based techniques (LDV, PIV or LIF), hot-film/wire anemometry, imaging, or other advanced measuring techniques. There were over 150 registered participants at the CFD4NRS-4 workshop. The programme consisted of 48 technical papers. Of these, 44 were presented orally and 4 as posters. An additional 8 posters related to the OECD/NEA-KAERI sponsored CFD benchmark exercise on turbulent mixing in a rod bundle with spacers (MATiS-H) were presented and a special session was allocated for 6 video presentations. In addition, five keynote lectures were given by distinguished experts. The

  17. Development and Implementation of CFD-Informed Models for the Advanced Subchannel Code CTF

    Science.gov (United States)

    Blyth, Taylor S.

    The research described in this PhD thesis contributes to the development of efficient methods for utilization of high-fidelity models and codes to inform low-fidelity models and codes in the area of nuclear reactor core thermal-hydraulics. The objective is to increase the accuracy of predictions of quantities of interests using high-fidelity CFD models while preserving the efficiency of low-fidelity subchannel core calculations. An original methodology named Physics-based Approach for High-to-Low Model Information has been further developed and tested. The overall physical phenomena and corresponding localized effects, which are introduced by the presence of spacer grids in light water reactor (LWR) cores, are dissected in corresponding four building basic processes, and corresponding models are informed using high-fidelity CFD codes. These models are a spacer grid-directed cross-flow model, a grid-enhanced turbulent mixing model, a heat transfer enhancement model, and a spacer grid pressure loss model. The localized CFD-models are developed and tested using the CFD code STAR-CCM+, and the corresponding global model development and testing in sub-channel formulation is performed in the thermal-hydraulic subchannel code CTF. The improved CTF simulations utilize data-files derived from CFD STAR-CCM+ simulation results covering the spacer grid design desired for inclusion in the CTF calculation. The current implementation of these models is examined and possibilities for improvement and further development are suggested. The validation experimental database is extended by including the OECD/NRC PSBT benchmark data. The outcome is an enhanced accuracy of CTF predictions while preserving the computational efficiency of a low-fidelity subchannel code.

  18. Development and Implementation of CFD-Informed Models for the Advanced Subchannel Code CTF

    Energy Technology Data Exchange (ETDEWEB)

    Blyth, Taylor S. [Pennsylvania State Univ., University Park, PA (United States); Avramova, Maria [North Carolina State Univ., Raleigh, NC (United States)

    2017-04-01

    The research described in this PhD thesis contributes to the development of efficient methods for utilization of high-fidelity models and codes to inform low-fidelity models and codes in the area of nuclear reactor core thermal-hydraulics. The objective is to increase the accuracy of predictions of quantities of interests using high-fidelity CFD models while preserving the efficiency of low-fidelity subchannel core calculations. An original methodology named Physics- based Approach for High-to-Low Model Information has been further developed and tested. The overall physical phenomena and corresponding localized effects, which are introduced by the presence of spacer grids in light water reactor (LWR) cores, are dissected in corresponding four building basic processes, and corresponding models are informed using high-fidelity CFD codes. These models are a spacer grid-directed cross-flow model, a grid-enhanced turbulent mixing model, a heat transfer enhancement model, and a spacer grid pressure loss model. The localized CFD-models are developed and tested using the CFD code STAR-CCM+, and the corresponding global model development and testing in sub-channel formulation is performed in the thermal- hydraulic subchannel code CTF. The improved CTF simulations utilize data-files derived from CFD STAR-CCM+ simulation results covering the spacer grid design desired for inclusion in the CTF calculation. The current implementation of these models is examined and possibilities for improvement and further development are suggested. The validation experimental database is extended by including the OECD/NRC PSBT benchmark data. The outcome is an enhanced accuracy of CTF predictions while preserving the computational efficiency of a low-fidelity subchannel code.

  19. Analysis research on mixing characteristics of lower plenum of Qinshan phase Ⅱ NPP by CFD method

    International Nuclear Information System (INIS)

    Mao Huihui; He Peifeng; Lu Chuan; Zhang Hongliang

    2015-01-01

    The flowing and mixing characteristics of the lower plenum of Qinshan Phase n NPP were analyzed by CFD method. The calculation results were compared with the results of the reactor hydraulic simulation test. On core inlet mass flow distributions, both upwind and high resolution advection schemes show good agreements with test results. While on lower plenum mixing characteristics, the calculation results from either upwind or high resolution advection schemes show relatively large differences to the test data. Relatively, upwind advection schemes predict better anticipations on maximum and minimum mixing factors. Furthermore, whether or not considering helix flow by main pump is the most possible key factor that leads to difference between CFD calculation and test results. (authors)

  20. Coil protection calculator for TFTR

    International Nuclear Information System (INIS)

    Marsala, R.J.; Woolley, R.D.

    1987-01-01

    A new coil protection calculator (CPC) is presented in this paper. It is now being developed for TFTR's magnetic field coils will replace the existing coil fault detector. The existing fault detector sacrifices TFTR operating capability for simplicity. The new CPC will permit operation up to the actual coil limits by accurately and continuously computing coil parameters in real-time. The improvement will allow TFTR to operate with higher plasma currents and will permit the optimization of pulse repetition rates

  1. CFD application to supersonic/hypersonic inlet airframe integration. [computational fluid dynamics (CFD)

    Science.gov (United States)

    Benson, Thomas J.

    1988-01-01

    Supersonic external compression inlets are introduced, and the computational fluid dynamics (CFD) codes and tests needed to study flow associated with these inlets are outlined. Normal shock wave turbulent boundary layer interaction is discussed. Boundary layer control is considered. Glancing sidewall shock interaction is treated. The CFD validation of hypersonic inlet configurations is explained. Scramjet inlet modules are shown.

  2. Assessment of CFD Hypersonic Turbulent Heating Rates for Space Shuttle Orbiter

    Science.gov (United States)

    Wood, William A.; Oliver, A. Brandon

    2011-01-01

    Turbulent CFD codes are assessed for the prediction of convective heat transfer rates at turbulent, hypersonic conditions. Algebraic turbulence models are used within the DPLR and LAURA CFD codes. The benchmark heat transfer rates are derived from thermocouple measurements of the Space Shuttle orbiter Discovery windward tiles during the STS-119 and STS-128 entries. The thermocouples were located underneath the reaction-cured glass coating on the thermal protection tiles. Boundary layer transition flight experiments conducted during both of those entries promoted turbulent flow at unusually high Mach numbers, with the present analysis considering Mach 10{15. Similar prior comparisons of CFD predictions directly to the flight temperature measurements were unsatisfactory, showing diverging trends between prediction and measurement for Mach numbers greater than 11. In the prior work, surface temperatures and convective heat transfer rates had been assumed to be in radiative equilibrium. The present work employs a one-dimensional time-accurate conduction analysis to relate measured temperatures to surface heat transfer rates, removing heat soak lag from the flight data, in order to better assess the predictive accuracy of the numerical models. The turbulent CFD shows good agreement for turbulent fuselage flow up to Mach 13. But on the wing in the wake of the boundary layer trip, the inclusion of tile conduction effects does not explain the prior observed discrepancy in trends between simulation and experiment; the flight heat transfer measurements are roughly constant over Mach 11-15, versus an increasing trend with Mach number from the CFD.

  3. OECD/NEA International Benchmark exercises: Validation of CFD codes applied nuclear industry; OECD/NEA internatiion Benchmark exercices: La validacion de los codigos CFD aplicados a la industria nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Pena-Monferrer, C.; Miquel veyrat, A.; Munoz-Cobo, J. L.; Chiva Vicent, S.

    2016-08-01

    In the recent years, due, among others, the slowing down of the nuclear industry, investment in the development and validation of CFD codes, applied specifically to the problems of the nuclear industry has been seriously hampered. Thus the International Benchmark Exercise (IBE) sponsored by the OECD/NEA have been fundamental to analyze the use of CFD codes in the nuclear industry, because although these codes are mature in many fields, still exist doubts about them in critical aspects of thermohydraulic calculations, even in single-phase scenarios. The Polytechnic University of Valencia (UPV) and the Universitat Jaume I (UJI), sponsored by the Nuclear Safety Council (CSN), have actively participated in all benchmark's proposed by NEA, as in the expert meetings,. In this paper, a summary of participation in the various IBE will be held, describing the benchmark itself, the CFD model created for it, and the main conclusions. (Author)

  4. Comparing different CFD wind turbine modelling approaches with wind tunnel measurements

    International Nuclear Information System (INIS)

    Kalvig, Siri; Hjertager, Bjørn; Manger, Eirik

    2014-01-01

    The performance of a model wind turbine is simulated with three different CFD methods: actuator disk, actuator line and a fully resolved rotor. The simulations are compared with each other and with measurements from a wind tunnel experiment. The actuator disk is the least accurate and most cost-efficient, and the fully resolved rotor is the most accurate and least cost-efficient. The actuator line method is believed to lie in between the two ends of the scale. The fully resolved rotor produces superior wake velocity results compared to the actuator models. On average it also produces better results for the force predictions, although the actuator line method had a slightly better match for the design tip speed. The open source CFD tool box, OpenFOAM, was used for the actuator disk and actuator line calculations, whereas the market leading commercial CFD code, ANSYS/FLUENT, was used for the fully resolved rotor approach

  5. 2D CFD Airfoil Analysis

    Science.gov (United States)

    Babb, Grace

    2017-11-01

    This work aims to produce a higher fidelity model of the blades for NASA's X-57 all electric propeller driven experimental aircraft. This model will, in turn, allow for more accurate calculations of the thrust each propeller can generate. This work uses computational fluid dynamics (CFD) to first analyze the propeller blades as a series of 11 differently shaped airfoils and calculate, among other things, the coefficients for lift and drag associated with each airfoil at different angles of attack. OpenFOAM-a C + + library that can be used to create series of applications for pre-processing, solving, and post-processing-is one of the primary tools utilized in these calculations. By comparing the data OpenFOAM generates about the NACA 23012 airfoil with existing experimental data about the NACA 23012 airfoil, the reliability of our model is measured and verified. A trustworthy model can then be used to generate more data and sent to NASA to aid in the design of the actual aircraft.

  6. Virtual maneuvering test in CFD media in presence of free surface

    Directory of Open Access Journals (Sweden)

    Ahmad Hajivand

    2015-05-01

    Full Text Available Maneuvering oblique towing test is simulated in a Computational Fluid Dynamic (CFD environment to obtain the linear and nonlinear velocity dependent damping coefficients for a DTMB 5512 model ship. The simulations are carried out in freely accessible OpenFOAM library with three different solvers, rasInterFoam, LTSInterFoam and interDyMFoam, and two turbulence models, k-ε and SST k-ω in presence of free surface. Turning and zig-zag maneuvers are simulated for the DTMB 5512 model ship using the calculated damping coefficients with CFD. The comparison of simulated results with the available experimental shows a very good agreement among them.

  7. CFD Analysis of Experimental Wing and Winglet for FalconLAUNCH 8 and the ExFIT Program

    Science.gov (United States)

    2010-03-01

    the interaction of the winglet shock wave with the main wing. It is important to note here that the main wing has both aerodynamic and geometric twist...CFD Analysis of Experimental Wing and Winglet for FalconLAUNCH 8 and the ExFIT Program THESIS Benjamin P. Switzer, Second Lieutenant, USAF AFIT/GAE...to copyright protection in the United States. AFIT/GAE/ENY/10-M25 CFD Analysis of Experimental Wing and Winglet for FalconLAUNCH 8 and the ExFIT

  8. CFD simulations for engine intake manifolds

    International Nuclear Information System (INIS)

    Witry, A.; Zhao, A.

    2002-01-01

    This paper attempts to explain a procedure for using Computational Fluid Dynamics (CFD) for product development of engine intake manifolds. The paper uses the development of an intake manifold as an example of such a process. Using the commercial FLUENT solver, its standard wall functions and k-ε model, a four runner intake manifold with an average mesh size of 300, 000 hexa elements created in ICEM-CFD with a maximum skewness of 0.85 produces rapid results for quick product turn-around times. The setup used allows for compressibility and viscous heating effects to be modeled whilst ignoring wall heat transfer due to the high speeds of the air/foil mixture and low residence times. Eight consecutive models were modeled here whilst carrying out continuous enhancements. For every iteration, four different so called 'static' runs with only one runner open at any one time using a steady state assumption were calculated further assuming that only one intake valve is open at any one time. Even flow distributions between the runner are deemed to be 'dynamically' obtained once the pressure drops between the manifold's inlet and runner outlets are equalized. Furthermore, different modifications were attempted to ensure that the fluid's particle tracks show very little particle return tendencies along with excellent nonuniformity indexes at the runners outlets. Confirmation of these results were obtained from test data showing CFD pressure drop predictions to be within 4% error with 67% of any runner's pressure losses being caused in the runner itself due to the small cross sectional area(s). (author)

  9. Implementation of CFD module in the KORSAR thermal-hydraulic system code

    Energy Technology Data Exchange (ETDEWEB)

    Yudov, Yury V.; Danilov, Ilia G.; Chepilko, Stepan S. [Alexandrov Research Inst. of Technology (NITI), Sosnovy Bor (Russian Federation)

    2015-09-15

    The Russian KORSAR/GP (hereinafter KORSAR) computer code was developed by a joint team from Alexandrov NITI and OKB ''Gidropress'' for VVER safety analysis and certified by the Rostechnadzor of Russia in 2009. The code functionality is based on a 1D two-fluid model for calculation of two-phase flows. A 3D CFD module in the KORSAR computer code is being developed by Alexandrov NITI for representing 3D effects in the downcomer and lower plenum during asymmetrical loop operation. The CFD module uses Cartesian grid method with cut cell approach. The paper presents a numerical algorithm for coupling 1D and 3D thermal- hydraulic modules in the KORSAR code. The combined pressure field is calculated by the multigrid method. The performance efficiency of the algorithm for coupling 1D and 3D modules was demonstrated by solving the benchmark problem of mixing cold and hot flows in a T-junction.

  10. Computational Fluid Dynamics (CFD) for Nuclear Reactor Safety Applications - Workshop Proceedings, CFD4NRS-3 - Experimental Validation and Application of CFD and CMFD Codes to Nuclear Reactor Safety Issues

    International Nuclear Information System (INIS)

    2012-01-01

    The purpose of the workshop was to provide a forum for numerical analysts and experimentalists to exchange information in the field of NRS-related activities relevant to CFD validation, with the objective of providing input to WGAMA CFD experts to create a practical, state-of-the-art, web-based assessment matrix on the use of CFD for NRS applications. The workshop included single-phase and multiphase CFD applications as well as new experimental techniques, including the following: Single-phase and two-phase CFD simulations with an emphasis on validation were sought in areas such as boiling flows, free-surface flows, direct contact condensation, and turbulent mixing. These should relate to NRS-relevant issues such as pressurized thermal shock, critical heat flux, pool heat exchangers, boron dilution, hydrogen distribution, and thermal striping. The use of systematic error quantification and Best Practice Guidelines (BPGs) was encouraged. Experiments providing data suitable for CFD validation-specifically in the area of NRS-including local measurement devices such as multi-sensor optical or electrical probes, Laser Doppler Velocimetry (LDV), hot-film/wire anemometry, Particle Image Velocimetry (PIV), Laser-Induced Fluorescence (LIF), and other innovative techniques. There were over 200 registered participants at the CFD4NRS-3 workshop. The program consisted of about 75 technical papers. Of these, 57 were oral presentations and 19 were posters. An additional 20 posters related to the OECD/NEA-sponsored CFD benchmark exercise on thermal fatigue in a T-Junction were presented. In addition, five keynote lectures were given by distinguished experts. This is about a 30 pc increase with respect to the previous XCFD4NRS workshop held in Grenoble in 2008, and a 70 pc increase compared to the first CFD4NRS workshop held in Garching in 2006. This confirms that there is a real and growing need for such workshops. The papers presented in the conference tackled different topics

  11. Developing a methodology for the evaluation of results uncertainties in CFD codes; Desarrollo de una Metodologia para la Evaluacion de Incertidumbres en los Resultados de Codigos de CFD

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-cobo, J. L.; Chiva, S.; Pena, C.; Vela, E.

    2014-07-01

    In this work the development of a methodology is studied to evaluate the uncertainty in the results of CFD codes and is compatible with the VV-20 standard Standard for Verification and Validation in CFD and Heat Transfer {sup ,} developed by the Association of Mechanical Engineers ASME . Similarly, the alternatives are studied for obtaining existing uncertainty in the results to see which is the best choice from the point of view of implementation and time. We have developed two methods for calculating uncertainty of the results of a CFD code, the first method based on the use of techniques of Monte-Carlo for the propagation of uncertainty in this first method we think it is preferable to use the statistics of the order to determine the number of cases to execute the code, because this way we can always determine the confidence interval desired level of output quantities. The second type of method we have developed is based on non-intrusive polynomial chaos. (Author)

  12. Twelfth annual conference of the CFD Society of Canada (CFD 2004). Proceedings

    International Nuclear Information System (INIS)

    Khalid, M.; Chen, S.; McIlwain, S.

    2004-01-01

    The Twelfth Annual Conference of the CFD Society of Canada, CFD 2004, was held in Ottawa, Ontario from May 9-11, 2004. The proceedings consists of 24 sessions covering the following topics: fluid structure interactions; multiphase and multi-species flows; mesh methods; turbulence; DNS/LES; supersonic and hypersonic flows; heat transfer; combustion and detonation; flow physics; aerodynamics; applications; algorithms; environmental flows; magnetohydrodynamics and electrohydrodynamics; biofluids; and, combustion and smoke management

  13. A simplified treatment of the boundary conditions of the k- ε model in coarse-mesh CFD-type codes

    International Nuclear Information System (INIS)

    Analytis, G.Th.; Andreani, M.

    1999-01-01

    In coarse-mesh, CFD-type codes such as the containment analysis code GOTHIC, one of the options that can be used for modelling of turbulence is the k - ε model. However, in contrast to most other CFD codes which are designed to perform detailed CFD calculations with a large number of spatial meshes, codes such as GOTHIC are primarily aimed at simplified calculation of transients in large spaces (e.g., reactor containments), and generally use coarse meshes. The solution of the two parabolic equations for the k - ε model requires the definition of boundary conditions at physical boundaries and this, in turn, requires very small spatial meshes near these boundaries. Hence, while in codes like CFX this is done in a rigorous and consistent manner, codes like GOTHIC adopt an indirect and heuristic approach, due to the fact that the spatial meshes are usually large. This can have adverse consequences during the calculation of a transient and in this work, we shall give some examples of this and outline a method by which this problem can be avoided. (author)

  14. Modeling Subgrid Scale Droplet Deposition in Multiphase-CFD

    Science.gov (United States)

    Agostinelli, Giulia; Baglietto, Emilio

    2017-11-01

    The development of first-principle-based constitutive equations for the Eulerian-Eulerian CFD modeling of annular flow is a major priority to extend the applicability of multiphase CFD (M-CFD) across all two-phase flow regimes. Two key mechanisms need to be incorporated in the M-CFD framework, the entrainment of droplets from the liquid film, and their deposition. Here we focus first on the aspect of deposition leveraging a separate effects approach. Current two-field methods in M-CFD do not include appropriate local closures to describe the deposition of droplets in annular flow conditions. As many integral correlations for deposition have been proposed for lumped parameters methods applications, few attempts exist in literature to extend their applicability to CFD simulations. The integral nature of the approach limits its applicability to fully developed flow conditions, without geometrical or flow variations, therefore negating the scope of CFD application. A new approach is proposed here that leverages local quantities to predict the subgrid-scale deposition rate. The methodology is first tested into a three-field approach CFD model.

  15. Overview of hypersonic CFD code calibration studies

    Science.gov (United States)

    Miller, Charles G.

    1987-01-01

    The topics are presented in viewgraph form and include the following: definitions of computational fluid dynamics (CFD) code validation; climate in hypersonics and LaRC when first 'designed' CFD code calibration studied was initiated; methodology from the experimentalist's perspective; hypersonic facilities; measurement techniques; and CFD code calibration studies.

  16. CFD Analyses of Re-Evolved Iodine from an In-containment Water Pool

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Hyeon [KHNP CRI, Daejeon (Korea, Republic of); Yoon, Woo Sung; Jung, Ji Hwan [Pusan National University, Busan (Korea, Republic of)

    2016-10-15

    A good understanding of the behavior of iodine is required to evaluate the safety and emergency procedures after a LOCA. The quantity of re-evolved iodine is related to pH level, temperature, and iodine concentration of water pool. In the calculation of pH for water pool, sequence calculations must consider this variable if any aqueous iodine is present, even if it is initially present in stable forms. The present study consists of two parts: the pH evaluation and the evaluation of the iodine re-evolution. The current paper focuses on the pH evaluation method, the development of a user-defined function (UDF) and the iodine re-evolution from the water pool. CFD that incorporates the UDF was used in this study to calculate the local pH level in the transient condition. The amount of re-evolved iodine was calculated based on the iodine concentration, temperature, and pH. The transportation and resulting distribution of the iodine concentration, temperature, and pH were calculated using transient analyses with CFD. The quantity of reevolved iodine was obtained with several assumptions. The quantitative evaluation of re-evolved iodine during a LOCA in a commercial nuclear power plants is done in two stages. The first stage is to calculate the pH in the water pool, and the second stage is to calculate the quantity of re-evolved iodine. Evaporated iodine, from the water pool water to the containment atmosphere, can be estimated from characteristic iodine behaviors and pH calculations. The 3D CFD analysis results show that the pH reached 7.0 after 149.5 minutes. Near the spillway, the change in averaged pH was faster than the change in wholevolume averaged pH. Evaluating the amount of reevolved iodine were examined using four different methods. As a result of our evaluation of iodine reevolution, the initial molecular iodine concentration of a water pool has a significant impact on the amount of gaseous iodine, more so than the pH or temperature, due to the locally similar

  17. CFD Analyses of Re-Evolved Iodine from an In-containment Water Pool

    International Nuclear Information System (INIS)

    Kim, Tae Hyeon; Yoon, Woo Sung; Jung, Ji Hwan

    2016-01-01

    A good understanding of the behavior of iodine is required to evaluate the safety and emergency procedures after a LOCA. The quantity of re-evolved iodine is related to pH level, temperature, and iodine concentration of water pool. In the calculation of pH for water pool, sequence calculations must consider this variable if any aqueous iodine is present, even if it is initially present in stable forms. The present study consists of two parts: the pH evaluation and the evaluation of the iodine re-evolution. The current paper focuses on the pH evaluation method, the development of a user-defined function (UDF) and the iodine re-evolution from the water pool. CFD that incorporates the UDF was used in this study to calculate the local pH level in the transient condition. The amount of re-evolved iodine was calculated based on the iodine concentration, temperature, and pH. The transportation and resulting distribution of the iodine concentration, temperature, and pH were calculated using transient analyses with CFD. The quantity of reevolved iodine was obtained with several assumptions. The quantitative evaluation of re-evolved iodine during a LOCA in a commercial nuclear power plants is done in two stages. The first stage is to calculate the pH in the water pool, and the second stage is to calculate the quantity of re-evolved iodine. Evaporated iodine, from the water pool water to the containment atmosphere, can be estimated from characteristic iodine behaviors and pH calculations. The 3D CFD analysis results show that the pH reached 7.0 after 149.5 minutes. Near the spillway, the change in averaged pH was faster than the change in wholevolume averaged pH. Evaluating the amount of reevolved iodine were examined using four different methods. As a result of our evaluation of iodine reevolution, the initial molecular iodine concentration of a water pool has a significant impact on the amount of gaseous iodine, more so than the pH or temperature, due to the locally similar

  18. Preliminary Computational Fluid Dynamics (CFD) Simulation of EIIB Push Barge in Shallow Water

    Science.gov (United States)

    Beneš, Petr; Kollárik, Róbert

    2011-12-01

    This study presents preliminary CFD simulation of EIIb push barge in inland conditions using CFD software Ansys Fluent. The RANSE (Reynolds Averaged Navier-Stokes Equation) methods are used for the viscosity solution of turbulent flow around the ship hull. Different RANSE methods are used for the comparison of their results in ship resistance calculations, for selecting the appropriate and removing inappropriate methods. This study further familiarizes on the creation of geometrical model which considers exact water depth to vessel draft ratio in shallow water conditions, grid generation, setting mathematical model in Fluent and evaluation of the simulations results.

  19. High fidelity thermal-hydraulic analysis using CFD and massively parallel computers

    International Nuclear Information System (INIS)

    Weber, D.P.; Wei, T.Y.C.; Brewster, R.A.; Rock, Daniel T.; Rizwan-uddin

    2000-01-01

    Thermal-hydraulic analyses play an important role in design and reload analysis of nuclear power plants. These analyses have historically relied on early generation computational fluid dynamics capabilities, originally developed in the 1960s and 1970s. Over the last twenty years, however, dramatic improvements in both computational fluid dynamics codes in the commercial sector and in computing power have taken place. These developments offer the possibility of performing large scale, high fidelity, core thermal hydraulics analysis. Such analyses will allow a determination of the conservatism employed in traditional design approaches and possibly justify the operation of nuclear power systems at higher powers without compromising safety margins. The objective of this work is to demonstrate such a large scale analysis approach using a state of the art CFD code, STAR-CD, and the computing power of massively parallel computers, provided by IBM. A high fidelity representation of a current generation PWR was analyzed with the STAR-CD CFD code and the results were compared to traditional analyses based on the VIPRE code. Current design methodology typically involves a simplified representation of the assemblies, where a single average pin is used in each assembly to determine the hot assembly from a whole core analysis. After determining this assembly, increased refinement is used in the hot assembly, and possibly some of its neighbors, to refine the analysis for purposes of calculating DNBR. This latter calculation is performed with sub-channel codes such as VIPRE. The modeling simplifications that are used involve the approximate treatment of surrounding assemblies and coarse representation of the hot assembly, where the subchannel is the lowest level of discretization. In the high fidelity analysis performed in this study, both restrictions have been removed. Within the hot assembly, several hundred thousand to several million computational zones have been used, to

  20. Non-Intrusive Computational Method and Uncertainty Quantification Tool for isolator operability calculations, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Computational fluid dynamics (CFD) simulations are extensively used by NASA for hypersonic aerothermodynamics calculations. The physical models used in CFD codes and...

  1. Coupled full core neutron transport/CFD simulations of pressurized water reactors

    International Nuclear Information System (INIS)

    Kochunas, B.; Stimpson, S.; Collins, B.; Downar, T.; Brewster, R.; Baglietto, E.; Yan, J.

    2012-01-01

    Recently as part of the CASL project, a capability to perform 3D whole-core coupled neutron transport and computational fluid dynamics (CFD) calculations was demonstrated. This work uses the 2D/1D transport code DeCART and the commercial CFD code STAR-CCM+. It builds on previous CASL work demonstrating coupling for smaller spatial domains. The coupling methodology is described along with the problem simulated and results are presented for fresh hot full power conditions. An additional comparison is made to an equivalent model that uses lower order T/H feedback to assess the importance and cost of high fidelity feedback to the neutronics problem. A simulation of a quarter core Combustion Engineering (CE) PWR core was performed with the coupled codes using a Fixed Point Gauss-Seidel iteration technique. The total approximate calculation requirements are nearly 10,000 CPU hours and 1 TB of memory. The problem took 6 coupled iterations to converge. The CFD coupled model and low order T/H feedback model compared well for global solution parameters, with a difference in the critical boron concentration and average outlet temperature of 14 ppm B and 0.94 deg. C, respectively. Differences in the power distribution were more significant with maximum relative differences in the core-wide pin peaking factor (Fq) of 5.37% and average relative differences in flat flux region power of 11.54%. Future work will focus on analyzing problems more relevant to CASL using models with less approximations. (authors)

  2. CFD Studies on Biomass Thermochemical Conversion

    Directory of Open Access Journals (Sweden)

    Lifeng Yan

    2008-06-01

    Full Text Available Thermochemical conversion of biomass offers an efficient and economically process to provide gaseous, liquid and solid fuels and prepare chemicals derived from biomass. Computational fluid dynamic (CFD modeling applications on biomass thermochemical processes help to optimize the design and operation of thermochemical reactors. Recent progression in numerical techniques and computing efficacy has advanced CFD as a widely used approach to provide efficient design solutions in industry. This paper introduces the fundamentals involved in developing a CFD solution. Mathematical equations governing the fluid flow, heat and mass transfer and chemical reactions in thermochemical systems are described and sub-models for individual processes are presented. It provides a review of various applications of CFD in the biomass thermochemical process field.

  3. Integrating CFD and building simulation

    DEFF Research Database (Denmark)

    Bartak, M.; Beausoleil-Morrison, I.; Clarke, J.A.

    2002-01-01

    Commission, which furthered the CFD modelling aspects of the ESP-r system. The paper summarises the form of the CFD model, describes the method used to integrate the thermal and 3ow domains and reports the outcome from an empirical validation exercise. © 2002 Published by Elsevier Science Ltd....

  4. Controls/CFD Interdisciplinary Research Software Generates Low-Order Linear Models for Control Design From Steady-State CFD Results

    Science.gov (United States)

    Melcher, Kevin J.

    1997-01-01

    The NASA Lewis Research Center is developing analytical methods and software tools to create a bridge between the controls and computational fluid dynamics (CFD) disciplines. Traditionally, control design engineers have used coarse nonlinear simulations to generate information for the design of new propulsion system controls. However, such traditional methods are not adequate for modeling the propulsion systems of complex, high-speed vehicles like the High Speed Civil Transport. To properly model the relevant flow physics of high-speed propulsion systems, one must use simulations based on CFD methods. Such CFD simulations have become useful tools for engineers that are designing propulsion system components. The analysis techniques and software being developed as part of this effort are an attempt to evolve CFD into a useful tool for control design as well. One major aspect of this research is the generation of linear models from steady-state CFD results. CFD simulations, often used during the design of high-speed inlets, yield high resolution operating point data. Under a NASA grant, the University of Akron has developed analytical techniques and software tools that use these data to generate linear models for control design. The resulting linear models have the same number of states as the original CFD simulation, so they are still very large and computationally cumbersome. Model reduction techniques have been successfully applied to reduce these large linear models by several orders of magnitude without significantly changing the dynamic response. The result is an accurate, easy to use, low-order linear model that takes less time to generate than those generated by traditional means. The development of methods for generating low-order linear models from steady-state CFD is most complete at the one-dimensional level, where software is available to generate models with different kinds of input and output variables. One-dimensional methods have been extended

  5. Validation of CFD-methods to predict heat transfer and temperatures during the transport and storage of casks under a cover

    International Nuclear Information System (INIS)

    Leber, A.; Graf, W.; Hueggenberg, R.

    2004-01-01

    With respect to the transport of casks for radioactive material, the proof of the safe heat removal can be accomplished by validated calculation methods. The boundary conditions for thermal tests for type B packages are specified in the ADR based on the regulations defined by the International Atomic Energy Agency. The varying boundary conditions under transport or storage conditions are based on the varying thermal conditions true for different cask types. In most cases the cask will be transported in lying position under a cover (e.g. canopy or tarpaulin) and stored in standing position in an array with other casks. The main heat transport mechanisms are natural convection and thermal radiation. The cover or the storage building are furnished with vents that create an air flow, which will improve the natural convection. Depending on the thermal boundary conditions, the cask design and the heat power, about 50 - 95% of the heat power will be removed from the finned cask surface by natural convection. Consequently the convection by air flow is the main heat transport mechanism. The air flow can be approximated with analytical methods by solving the integral heat and flow balances for the domain. In a stationary state the overpressure due the buoyancy and the pressure loss in the flow resistances are equal. Based on the air flow, the relevant temperatures of the cask can be calculated in an iterative process. Due to the fast development of numerical calculation methods and computer hardware, the use of Computational- Fluid-Dynamics(CFD) calculations plays an important role. CFD-calculations are based on solving the equations of conservation (Navier-Stokes equations) using a finite element mesh or a finite volume mesh of the model. For a finned cask lying under a cover, where the main contributing element for heat removal is natural convection in combination with the thermal radiation, a CFD-calculation can be the most appropriate method. Common CFD-Codes are FLUENT

  6. A subchannel and CFD analysis of void distribution for the BWR fuel bundle test benchmark

    International Nuclear Information System (INIS)

    In, Wang-Kee; Hwang, Dae-Hyun; Jeong, Jae Jun

    2013-01-01

    Highlights: ► We analyzed subchannel void distributions using subchannel, system and CFD codes. ► The mean error and standard deviation at steady states were compared. ► The deviation of the CFD simulation was greater than those of the others. ► The large deviation of the CFD prediction is due to interface model uncertainties. -- Abstract: The subchannel grade and microscopic void distributions in the NUPEC (Nuclear Power Engineering Corporation) BFBT (BWR Full-Size Fine-Mesh Bundle Tests) facility have been evaluated with a subchannel analysis code MATRA, a system code MARS and a CFD code CFX-10. Sixteen test series from five different test bundles were selected for the analysis of the steady-state subchannel void distributions. Four test cases for a high burn-up 8 × 8 fuel bundle with a single water rod were simulated using CFX-10 for the microscopic void distribution benchmark. Two transient cases, a turbine trip without a bypass as a typical power transient and a re-circulation pump trip as a flow transient, were also chosen for this analysis. It was found that the steady-state void distributions calculated by both the MATRA and MARS codes coincided well with the measured data in the range of thermodynamic qualities from 5 to 25%. The results of the transient calculations were also similar to each other and very reasonable. The CFD simulation reproduced the overall radial void distribution trend which produces less vapor in the central part of the bundle and more vapor in the periphery. However, the predicted variation of the void distribution inside the subchannels is small, while the measured one is large showing a very high concentration in the center of the subchannels. The variations of the void distribution between the center of the subchannels and the subchannel gap are estimated to be about 5–10% for the CFD prediction and more than 20% for the experiment

  7. Application of CFD in Indonesian Research: A review

    Science.gov (United States)

    Ambarita, H.; Siregar, M. R.; Kishinami, K.; Daimaruya, M.; Kawai, H.

    2018-04-01

    Computational Fluid Dynamics (CFD) is a numerical method that solves fluid flow and related governing equations using a computational tool. The studies on CFD, its methodology and its application as a research tool, are increasing. In this study, application of CFD by Indonesian researcher is briefly reviewed. The main objective is to explore the characteristics of CFD applications in Indonesian researchers. Considering the size and reputation, this study uses Scopus publications indexed data base. All of the documents in Scopus related to CFD which is affiliated by at least one of Indonesian researcher are collected to be reviewed. Research topics, CFD method, and simulation results are reviewed in brief. The results show that there are 260 documents found in literature indexed by Scopus. These documents divided into research articles 125 titles, conference paper 135 titles, book 1 title and review 1 title. In the research articles, only limited researchers focused on the development of CFD methodology. Almost all of the articles focus on using CFD in a particular application, as a research tool, such as aircraft application, wind power and heat exchanger. The topics of the 125 research articles can be divided into 12 specific applications and 1 miscellaneous application. The most popular application is Heating Ventilating and Air Conditioning and followed by Reactor, Transportation and Heat Exchanger applications. The most popular commercial CFD code used is ANSYS Fluent and only several researchers use CFX.

  8. Development of Multi-physics (Multiphase CFD + MCNP) simulation for generic solution vessel power calculation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Jun [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-17

    The current study aims to predict the steady state power of a generic solution vessel and to develop a corresponding heat transfer coefficient correlation for a Moly99 production facility by conducting a fully coupled multi-physics simulation. A prediction of steady state power for the current application is inherently interconnected between thermal hydraulic characteristics (i.e. Multiphase computational fluid dynamics solved by ANSYS-Fluent 17.2) and the corresponding neutronic behavior (i.e. particle transport solved by MCNP6.2) in the solution vessel. Thus, the development of a coupling methodology is vital to understand the system behavior at a variety of system design and postulated operating scenarios. In this study, we report on the k-effective (keff) calculation for the baseline solution vessel configuration with a selected solution concentration using MCNP K-code modeling. The associated correlation of thermal properties (e.g. density, viscosity, thermal conductivity, specific heat) at the selected solution concentration are developed based on existing experimental measurements in the open literature. The numerical coupling methodology between multiphase CFD and MCNP is successfully demonstrated, and the detailed coupling procedure is documented. In addition, improved coupling methods capturing realistic physics in the solution vessel thermal-neutronic dynamics are proposed and tested further (i.e. dynamic height adjustment, mull-cell approach). As a key outcome of the current study, a multi-physics coupling methodology between MCFD and MCNP is demonstrated and tested for four different operating conditions. Those different operating conditions are determined based on the neutron source strength at a fixed geometry condition. The steady state powers for the generic solution vessel at various operating conditions are reported, and a generalized correlation of the heat transfer coefficient for the current application is discussed. The assessment of multi

  9. Relation between wall shear stress and carotid artery wall thickening MRI versus CFD

    DEFF Research Database (Denmark)

    Cibis, Merih; Potters, Wouter V.; Selwaness, Mariana

    2016-01-01

    Wall shear stress (WSS), a parameter associated with endothelial function, is calculated by computational fluid dynamics (CFD) or phase-contrast (PC) MRI measurements. Although CFD is common in WSS (WSSCFD) calculations, PC-MRI-based WSS (WSSMRI) is more favorable in population studies; since...... it is straightforward and less time consuming. However, it is not clear if WSSMRI and WSSCFD show similar associations with vascular pathology. Our aim was to test the associations between wall thickness (WT) of the carotid arteries and WSSMRI and WSSCFD. The subjects (n=14) with an asymptomatic carotid plaque who...... underwent MRI scans two times within 4 years of time were selected from the Rotterdam Study. We compared WSSCFD and WSSMRI at baseline and follow-up. Baseline WSSMRI and WSSCFD values were divided into 3 categories representing low, medium and high WSS tertiles. WT of each tertile was compared by a one...

  10. Status and outlook of CFD technology at Mitsubishi Heavy Industries Nagoya. Mitsubishi Meiko ni okeru CFD gijutsu no genjo to tenbo

    Energy Technology Data Exchange (ETDEWEB)

    Tanioka, T [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)

    1990-09-01

    The present and future were reviewed of CFD (computational fluid dynamics) technology in Nagoya Works, Mitsubishi Heavy Industries, Ltd., Japan. The progress of the role of CFD in aerodynamic design and progress of CFD technology were reviewed. The followings were illustrated as examples of CFD analysis: design of a main wing for transonic private aircrafts by backward analysis, analysis of an airframe shape for the MU300 jet airplane with a panel method, Navier-stokes (NS) analysis of a transonic wing section, NS analysis of pressure distributions on the surfaces of the YXX airplane and space shuttle HOPE, and NS analysis of an aerodynamic heating distribution for spaceplanes. CFD tools were outlined for every developmental item such as a main wing, and requirements and subjects in practical use were discussed of several CFD tools for a rough check, precise performance check and parametric study. Such computer performance as a main memory capacity and processing speed required for the future practical use of advanced CFD was also discussed. 20 figs.

  11. Synthesis of the turbulent mixing in a rod bundle with vaned spacer grids based on the OECD-KAERI CFD benchmark exercise

    International Nuclear Information System (INIS)

    Lee, Jae Ryong; Kim, Jungwoo; Song, Chul-Hwa

    2014-01-01

    Highlights: • OECD/KAERI international CFD benchmark exercise was operated by KAERI. • The purpose is to validate relevant CFD codes based on the MATiS-H experiments. • Blind calculation results were synthesized in terms of mean velocity and RMS. • Quality of control volume rather than the number of it was emphasized. • Major findings were followed OECD/NEA CSNI report. - Abstract: The second international CFD benchmark exercise on turbulent mixing in a rod bundle has been launched by OECD/NEA, to validate relevant CFD (Computational Fluid Dynamics) codes and develop problem-specific Best Practice Guidelines (BPG) based on the KAERI (Korea Atomic Energy Research Institute) MATiS-H experiments on the turbulent mixing in a 5 × 5 rod array having two different types of vaned spacer grids: split and swirl types. For this 2nd international benchmark exercise (IBE-2), the MATiS-H testing provided a unique set of experimental data such as axial and lateral velocity components, turbulent intensity, and vorticity information. Blind CFD calculation results were submitted by twenty-five (25) participants to KAERI, who is the host organization of the IBE-2, and then analyzed and synthesized by comparing them with the MATiS-H data. Based on the synthesis of the results from both the experiments and blind CFD calculations for the IBE-2, and also by comparing with the IBE-1 benchmark exercise on the mixing in a T-junction, useful information for simulating this kind of complicated physical problem in a rod bundle was obtained. And some additional Best Practice Guidelines (BPG) are newly proposed. A summary of the synthesis results obtained in the IBE-2 is presented in this paper

  12. Synthesis of the turbulent mixing in a rod bundle with vaned spacer grids based on the OECD-KAERI CFD benchmark exercise

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Ryong; Kim, Jungwoo; Song, Chul-Hwa, E-mail: chsong@kaeri.re.kr

    2014-11-15

    Highlights: • OECD/KAERI international CFD benchmark exercise was operated by KAERI. • The purpose is to validate relevant CFD codes based on the MATiS-H experiments. • Blind calculation results were synthesized in terms of mean velocity and RMS. • Quality of control volume rather than the number of it was emphasized. • Major findings were followed OECD/NEA CSNI report. - Abstract: The second international CFD benchmark exercise on turbulent mixing in a rod bundle has been launched by OECD/NEA, to validate relevant CFD (Computational Fluid Dynamics) codes and develop problem-specific Best Practice Guidelines (BPG) based on the KAERI (Korea Atomic Energy Research Institute) MATiS-H experiments on the turbulent mixing in a 5 × 5 rod array having two different types of vaned spacer grids: split and swirl types. For this 2nd international benchmark exercise (IBE-2), the MATiS-H testing provided a unique set of experimental data such as axial and lateral velocity components, turbulent intensity, and vorticity information. Blind CFD calculation results were submitted by twenty-five (25) participants to KAERI, who is the host organization of the IBE-2, and then analyzed and synthesized by comparing them with the MATiS-H data. Based on the synthesis of the results from both the experiments and blind CFD calculations for the IBE-2, and also by comparing with the IBE-1 benchmark exercise on the mixing in a T-junction, useful information for simulating this kind of complicated physical problem in a rod bundle was obtained. And some additional Best Practice Guidelines (BPG) are newly proposed. A summary of the synthesis results obtained in the IBE-2 is presented in this paper.

  13. Performance assessment of the commercial CFD software for the prediction of the PWR internal flow - Corrected version

    International Nuclear Information System (INIS)

    Lee, Gong Hee; Bang, Young Seok; Woo, Sweng Woong; Cheong, Ae Ju; Kim, Do Hyeong; Kang, Min Ku

    2013-01-01

    As the computer hardware technology develops the license applicants for nuclear power plant use the commercial CFD software with the aim of reducing the excessive conservatism associated with using simplified and conservative analysis tools. Even if some of CFD software developers and its users think that a state of the art CFD software can be used to solve reasonably at least the single-phase nuclear reactor safety problems there is still the limitations and the uncertainties in the calculation result. From a regulatory perspective, Korea Institute of Nuclear Safety (KINS) has been presently conducting the performance assessment of the commercial CFD software for the nuclear reactor safety problems. In this study, in order to examine the prediction performance of the commercial CFD software with the porous model in the analysis of the scale-down APR+ (Advanced Power Reactor Plus) internal flow, simulation was conducted with the on-board numerical models in ANSYS CFX R.14 and FLUENT R.14. It was concluded that depending on the CFD software the internal flow distribution of the scale-down APR+ was locally some-what different. Although there was a limitation in estimating the prediction performance of the commercial CFD software due to the limited number of the measured data, CFXR.14 showed the more reasonable predicted results in comparison with FLUENT R.14. Meanwhile, due to the difference of discretization methodology, FLUENT R.14 required more computational memory than CFX R.14 for the same grid system. Therefore the CFD software suitable to the available computational resource should be selected for the massive parallel computation. (authors)

  14. A supportive architecture for CFD-based design optimisation

    Science.gov (United States)

    Li, Ni; Su, Zeya; Bi, Zhuming; Tian, Chao; Ren, Zhiming; Gong, Guanghong

    2014-03-01

    Multi-disciplinary design optimisation (MDO) is one of critical methodologies to the implementation of enterprise systems (ES). MDO requiring the analysis of fluid dynamics raises a special challenge due to its extremely intensive computation. The rapid development of computational fluid dynamic (CFD) technique has caused a rise of its applications in various fields. Especially for the exterior designs of vehicles, CFD has become one of the three main design tools comparable to analytical approaches and wind tunnel experiments. CFD-based design optimisation is an effective way to achieve the desired performance under the given constraints. However, due to the complexity of CFD, integrating with CFD analysis in an intelligent optimisation algorithm is not straightforward. It is a challenge to solve a CFD-based design problem, which is usually with high dimensions, and multiple objectives and constraints. It is desirable to have an integrated architecture for CFD-based design optimisation. However, our review on existing works has found that very few researchers have studied on the assistive tools to facilitate CFD-based design optimisation. In the paper, a multi-layer architecture and a general procedure are proposed to integrate different CFD toolsets with intelligent optimisation algorithms, parallel computing technique and other techniques for efficient computation. In the proposed architecture, the integration is performed either at the code level or data level to fully utilise the capabilities of different assistive tools. Two intelligent algorithms are developed and embedded with parallel computing. These algorithms, together with the supportive architecture, lay a solid foundation for various applications of CFD-based design optimisation. To illustrate the effectiveness of the proposed architecture and algorithms, the case studies on aerodynamic shape design of a hypersonic cruising vehicle are provided, and the result has shown that the proposed architecture

  15. CFD simulation of direct contact condensation with ANSYS CFX using surface renewal theory based heat transfer coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Wanninger, Andreas; Ceuca, Sabin Cristian; Macian-Juan, Rafael [Technische Univ. Muenchen, Garching (Germany). Dept. of Nuclear Engineering

    2013-07-01

    Different approaches for the calculation of Direct Contact Condensation (DCC) using Heat Transfer Coefficients (HTC) based on the Surface Renewal Theory (SRT) are tested using the CFD simulation tool ANSYS CFX. The present work constitutes a preliminary study of the flow patterns and conditions observed using different HTC models. A complex 3D flow pattern will be observed in the CFD simulations as well as a strong coupling between the condensation rate and the two-phase flow dynamics. (orig.)

  16. DNBR calculation in digital core protection system by a subchannel analysis code

    International Nuclear Information System (INIS)

    In, W. K.; Yoo, Y. J.; Hwang, T. H.; Ji, S. K.

    2001-01-01

    The DNBR calculation uncertainty and DNBR margin were evaluated in digital core protection system by a thermal-hydrualic subchannel analysis code MATRA. A simplified thermal-hydraulic code CETOP is used to calculate on-line DNBR in core protection system at a digital PWR. The DNBR tuning process against a best-estimate subchannel analysis code is required for CETOP to ensure accurate and conservative DNBR calculation but not necessary for MATRA. The DNBR calculations by MATRA and CETOP were performed for a large number of operating condition in Yonggwang nulcear units 3-4 where the digitial core protection system is initially implemented in Korea. MATRA resulted in a less negative mean value (i.e., reduce the overconservatism) and a somewhat larger standard deviation of the DNBR error. The uncertainty corrected minimum DNBR by MATRA was shown to be higher by 1.8% -9.9% that the CETOP DNBR

  17. ADDRESSING HUMAN EXPOSURE TO AIR POLLUTANTS AROUND BUILDINGS IN URBAN AREAS WITH COMPUTATIONAL FLUID DYNAMICS (CFD) MODELS

    Science.gov (United States)

    Computational Fluid Dynamics (CFD) simulations provide a number of unique opportunities for expanding and improving capabilities for modeling exposures to environmental pollutants. The US Environmental Protection Agency's National Exposure Research Laboratory (NERL) has been c...

  18. CFD simulation of homogenisation time measured by radiotracers

    International Nuclear Information System (INIS)

    Thyn, J.; Novy, M.; Zitny, R.; Mostik, M.; Jahoda, M.

    2004-01-01

    A methodology for CFD (Computational Fluid Dynamics) simulation of radiotracer experiments was suggested. The most important parts of the methodology for validation of CFD results by radiotracers are: a) successful simulation of tracer experiment by CFD code (numerical solution of tracer dispersion in a stirred tank), which results in tracer concentration field at several time intervals; b) post-process data treatment, which uses detection chain description and which enables to simulate the detector measurement of homogenisation time from the tracer concentration field evaluated by CFD code. (author)

  19. Evaluation of general non-reflecting boundary conditions for industrial CFD applications

    Science.gov (United States)

    Basara, Branislav; Frolov, Sergei; Lidskii, Boris; Posvyanskii, Vladimir

    2007-11-01

    The importance of having proper boundary conditions for the calculation domain is a known issue in Computational Fluid Dynamics (CFD). In many situations, it is very difficult to define a correct boundary condition. The flow may enter and leave the computational domain at the same time and at the same boundary. In such circumstances, it is important that numerical implementation of boundary conditions enforces certain physical constraints leading to correct results which then ensures a better convergence rate. The aim of this paper is to evaluate recently proposed non-reflecting boundary conditions (Frolov et al., 2001, Advances in Chemical Propulsion) on industrial CFD applications. Derivation of the local non-reflecting boundary conditions at the open boundary is based on finding the solution of linearized Euler equations vanishing at infinity for both incompressible and compressible formulations. This is implemented into the in-house CFD package AVL FIRE and some numerical details will be presented as well. The key applications in this paper are from automotive industry, e.g. an external car aerodynamics, an intake port, etc. The results will show benefits of using effective non-reflecting boundary conditions.

  20. User Interface Developed for Controls/CFD Interdisciplinary Research

    Science.gov (United States)

    1996-01-01

    The NASA Lewis Research Center, in conjunction with the University of Akron, is developing analytical methods and software tools to create a cross-discipline "bridge" between controls and computational fluid dynamics (CFD) technologies. Traditionally, the controls analyst has used simulations based on large lumping techniques to generate low-order linear models convenient for designing propulsion system controls. For complex, high-speed vehicles such as the High Speed Civil Transport (HSCT), simulations based on CFD methods are required to capture the relevant flow physics. The use of CFD should also help reduce the development time and costs associated with experimentally tuning the control system. The initial application for this research is the High Speed Civil Transport inlet control problem. A major aspect of this research is the development of a controls/CFD interface for non-CFD experts, to facilitate the interactive operation of CFD simulations and the extraction of reduced-order, time-accurate models from CFD results. A distributed computing approach for implementing the interface is being explored. Software being developed as part of the Integrated CFD and Experiments (ICE) project provides the basis for the operating environment, including run-time displays and information (data base) management. Message-passing software is used to communicate between the ICE system and the CFD simulation, which can reside on distributed, parallel computing systems. Initially, the one-dimensional Large-Perturbation Inlet (LAPIN) code is being used to simulate a High Speed Civil Transport type inlet. LAPIN can model real supersonic inlet features, including bleeds, bypasses, and variable geometry, such as translating or variable-ramp-angle centerbodies. Work is in progress to use parallel versions of the multidimensional NPARC code.

  1. CFD for hypersonic airbreathing aircraft

    Science.gov (United States)

    Kumar, Ajay

    1989-01-01

    A general discussion is given on the use of advanced computational fluid dynamics (CFD) in analyzing the hypersonic flow field around an airbreathing aircraft. Unique features of the hypersonic flow physics are presented and an assessment is given of the current algorithms in terms of their capability to model hypersonic flows. Several examples of advanced CFD applications are then presented.

  2. CFD analysis of poison injection in AHWR calandria

    International Nuclear Information System (INIS)

    Kansal, A.K.; Kamble, M.T.; Maheshwari, N.K.; Vijayan, P.K.

    2014-01-01

    The present work intends to give details of design and performance validation of SDS-2. The performance is evaluated on the basis of dispersion of poison in calandria in a given period of time. Location of injection tube and injection holes, size of jet hole and number of holes are some of the design parameters which greatly affect dispersion of poison in calandria. A Computational Fluid Dynamic (CFD) study for axial and radial injection of poison was carried out using open source CFD code OpenFOAM. CFD benchmarking was done using experiments performed by Johari (Johari et al. 1997) to identify suitable turbulence model for this problem. An experimental facility simulating poison injection in moderator in presence of calandria tubes was used to further validate the CFD model is shown in the paper. CFD analysis was carried out for axial as well as radial injection for AHWR geometry. CFD analysis using OpenFOAM has been carried out to study high pressure poison injection for single jet of Shut Down System - 2 (SDS- 2) of Advanced Heavy Water Reactor (AHWR) for various design options. CFD model used in analysis have been validated with experimental data available in literature as well as experiments performed for AHWR specific geometry. Various turbulence models are tested and their adequacy for such flow problems has been established. The CFD model is then used to simulate poison injection for two design options for AHWR and their performance is compared. (author)

  3. CFD Analysis for the Steady State Test of CS28-1 Simulating High Temperature Chemical Reactions in CANDU Fuel Channel

    International Nuclear Information System (INIS)

    Park, Ju Hwan; Kang, Hyung Seok; Rhee, Bo Wook

    2006-05-01

    difference between CFD results and test data may be due to an error in radiation heat transfer calculation, or to a wrong assumption of inlet temperature distribution in the CFD analysis. The comparison result of the pressure tube also indicated that the discrete transfer model for radiation heat transfer calculation has an error because temperature difference of about 30 .deg. C at the outlet region is large compared with the comparison steam and FES temperature. A verification work of discrete transfer model and CFD sensitivity calculation using another assumed temperature distribution for the inlet should be performed. The CFD benchmark calculation for the post-blowdown test in CANDU fuel channel will be performed to assist the development of the new safety analysis strategy and develop the CFD analysis methodology which can be used in the safety analysis of CANDU

  4. Impact of CGNS on CFD Workflow

    Science.gov (United States)

    Poinot, M.; Rumsey, C. L.; Mani, M.

    2004-01-01

    CFD tools are an integral part of industrial and research processes, for which the amount of data is increasing at a high rate. These data are used in a multi-disciplinary fluid dynamics environment, including structural, thermal, chemical or even electrical topics. We show that the data specification is an important challenge that must be tackled to achieve an efficient workflow for use in this environment. We compare the process with other software techniques, such as network or database type, where past experiences showed how difficult it was to bridge the gap between completely general specifications and dedicated specific applications. We show two aspects of the use of CFD General Notation System (CGNS) that impact CFD workflow: as a data specification framework and as a data storage means. Then, we give examples of projects involving CFD workflows where the use of the CGNS standard leads to a useful method either for data specification, exchange, or storage.

  5. Development and validation of three-dimensional CFD techniques for reactor safety applications. Final report; Entwicklung und Validierung dreidimensionaler CFD Verfahren fuer Anwendungen in der Reaktorsicherheit. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, Sebastian; Palazzo, Simone; Papukchiev, Angel; Scheurer Martina

    2016-12-15

    The overall goal of the project RS 1506 ''Development and Validation of Three Dimensional CFD Methods for Reactor Safety Applications'' is the validation of Computational Fluid Dynamics (CFD) software for the simulation of three -dimensional thermo-hydraulic heat and fluid flow phenomena in nuclear reactors. For this purpose a wide spectrum of validation and test cases was selected covering fluid flow and heat transfer phenomena in the downcomer and in the core of pressurized water reactors. In addition, the coupling of the system code ATHLET with the CFD code ANSYS CFX was further developed and validated. The first choice were UPTF experiments where turbulent single- and two-phase flows were investigated in a 1:1 scaled model of a German KONVOI reactor. The scope of the CFD calculations covers thermal mixing and stratification including condensation in single- and two-phase flows. In the complex core region, the flow in a fuel assembly with spacer grid was simulated as defined in the OECD/NEA Benchmark MATIS-H. Good agreement are achieved when the geometrical and physical boundary conditions were reproduced as realistic as possible. This includes, in particular, the consideration of heat transfer to walls. The influence of wall modelling on CFD results was investigated on the TALL-3D T01 experiment. In this case, the dynamic three dimensional fluid flow and heat transfer phenomena were simulated in a Generation IV liquid metal cooled reactor. Concurrently to the validation work, the coupling of the system code ATHLET with the ANSYS CFX software was optimized and expanded for two-phase flows. Different coupling approaches were investigated, in order to overcome the large difference between CPU-time requirements of system and CFD codes. Finally, the coupled simulation system was validated by applying it to the simulation of the PSI double T-junction experiment, the LBE-flow in the MYRRA Spallation experiment and a demonstration test case

  6. Requirements for effective use of CFD in aerospace design

    Science.gov (United States)

    Raj, Pradeep

    1995-01-01

    This paper presents a perspective on the requirements that Computational Fluid Dynamics (CFD) technology must meet for its effective use in aerospace design. General observations are made on current aerospace design practices and deficiencies are noted that must be rectified for the U.S. aerospace industry to maintain its leadership position in the global marketplace. In order to rectify deficiencies, industry is transitioning to an integrated product and process development (IPPD) environment and design processes are undergoing radical changes. The role of CFD in producing data that design teams need to support flight vehicle development is briefly discussed. An overview of the current state of the art in CFD is given to provide an assessment of strengths and weaknesses of the variety of methods currently available, or under development, to produce aerodynamic data. Effectiveness requirements are examined from a customer/supplier view point with design team as customer and CFD practitioner as supplier. Partnership between the design team and CFD team is identified as an essential requirement for effective use of CFD. Rapid turnaround, reliable accuracy, and affordability are offered as three key requirements that CFD community must address if CFD is to play its rightful role in supporting the IPPD design environment needed to produce high quality yet affordable designs.

  7. Research on Fairing design and CFD Analysis of Submarine Pipeline Inspection ARV

    Directory of Open Access Journals (Sweden)

    Jin Xiaojian

    2017-01-01

    Full Text Available Along with the fast development of the ocean exploitation, the cost-effective requirement of autonomous & remotely operated vehicle (ARV, which can perform more complicated missions such as the oil exploitation and the inspection of the submarine pipeline is more urgent. The submarine pipeline inspection ARV can help us better understand, protect and efficiently utilize them for human welfare. Fairing design of a new detection ARV are introduced in this paper. In order to select an appropriate thruster that will achieve the required speed of the ARV, the ANSYS-CFX tools are used to predicted the drag force. The CFD results reveal the distribution of velocity and pressure values of the ARV. In order to verify the CFD modeling process, a towed body was developed and analyzed, compared against the corresponding physical test data.

  8. Hybrid CFD/CAA Modeling for Liftoff Acoustic Predictions

    Science.gov (United States)

    Strutzenberg, Louise L.; Liever, Peter A.

    2011-01-01

    This paper presents development efforts at the NASA Marshall Space flight Center to establish a hybrid Computational Fluid Dynamics and Computational Aero-Acoustics (CFD/CAA) simulation system for launch vehicle liftoff acoustics environment analysis. Acoustic prediction engineering tools based on empirical jet acoustic strength and directivity models or scaled historical measurements are of limited value in efforts to proactively design and optimize launch vehicles and launch facility configurations for liftoff acoustics. CFD based modeling approaches are now able to capture the important details of vehicle specific plume flow environment, identifY the noise generation sources, and allow assessment of the influence of launch pad geometric details and sound mitigation measures such as water injection. However, CFD methodologies are numerically too dissipative to accurately capture the propagation of the acoustic waves in the large CFD models. The hybrid CFD/CAA approach combines the high-fidelity CFD analysis capable of identifYing the acoustic sources with a fast and efficient Boundary Element Method (BEM) that accurately propagates the acoustic field from the source locations. The BEM approach was chosen for its ability to properly account for reflections and scattering of acoustic waves from launch pad structures. The paper will present an overview of the technology components of the CFD/CAA framework and discuss plans for demonstration and validation against test data.

  9. 2-D and 3-D CFD Investigation of NREL S826 Airfoil at Low Reynolds Numbers

    International Nuclear Information System (INIS)

    Cakmakcioglu, S C; Sert, I O; Tugluk, O; Sezer-Uzol, N

    2014-01-01

    In this study CFD investigation of flow over the NREL S826 airfoil is performed. NREL S826 airfoil was designed for HAWTs of 10-15 meter diameters. However, it is used in the NTNU wind turbine rotor model and low Reynolds number flow characteristics become important in the validations with the test cases of this rotor model. The airfoil CFD simulations are carried out in 2-D and 3-D computational domains. The k-rn SST turbulence model with Langtry-Menter (γ-Re θ ) transition prediction model for turbulence closure is used in the calculations. The Delayed DES is also performed in the stall region for comparisons. The results are compared with the available METUWIND experimental data, and are shown to be in fair agreement. It is observed that 3-D CFD analysis provides increased accuracy at increased computational cost

  10. Recent developments in CFD and their impact on fuel assembly optimization

    International Nuclear Information System (INIS)

    Lascar, Celine; Alleborn, Norbert; Leberig, Mario; Jones, J.; Martin, M.

    2010-01-01

    In the recent past, progress in computer hardware and in Computational Fluid Dynamics (CFD) codes has made CFD attractive for thermal-hydraulic applications of the nuclear industry. Available code systems have a separated treatment of 1-phase and 2-phase CFD. While 1-phase phenomena (relevant for example to determine pressure losses in fuel assembly) can be reliably predicted with today's CFD programs, 2-phase CFD is still in the process of strong development in modeling 2- phase phenomena. AREVA NP is investing major efforts and resources (i) to develop knowledge and mastery of CFD models, their associated parameters, and the ranges of applications; (ii) to ensure validation of the in-house CFD codes and methodologies by gathering a large experimental databank; and (iii) to build state-ofthe- art tools and hardware to support this CFD development. All CFD work presented in this paper was performed with the commercial code STAR-CD. (orig.)

  11. Comprehensive Approach to Verification and Validation of CFD Simulations Applied to Backward Facing Step-Application of CFD Uncertainty Analysis

    Science.gov (United States)

    Groves, Curtis E.; LLie, Marcel; Shallhorn, Paul A.

    2012-01-01

    There are inherent uncertainties and errors associated with using Computational Fluid Dynamics (CFD) to predict the flow field and there is no standard method for evaluating uncertainty in the CFD community. This paper describes an approach to -validate the . uncertainty in using CFD. The method will use the state of the art uncertainty analysis applying different turbulence niodels and draw conclusions on which models provide the least uncertainty and which models most accurately predict the flow of a backward facing step.

  12. CFD analysis of the flow in the near wake of a generic PWR mixing grid

    International Nuclear Information System (INIS)

    Bieder, Ulrich; Falk, François; Fauchet, Gauthier

    2015-01-01

    Highlights: • The flow in a 5 × 5 rod bundle with mixing grid is analyzed experimentally and with CFD. • LES and RANS (k–ε) calculations are performed. • The parallelism of the Trio-U code was tested with a strong scaling method. • Close downstream of the grid, k–ε and LES give similar results and fit well the experiment. - Abstract: The flow in fuel assemblies of PWRs with mixing grids has been analyzed with CFD calculations by numerous authors. The comparison between calculation and experiment has often shown an insensitivity of the calculated cross flow velocity on the turbulence modeling. The study presented here was carried out to confirm this result. The comparison between measurements in the AGATE facility (5 × 5 tube bundle) and Trio-U calculations with a linear eddy viscosity turbulence model (k–ε) and Large Eddy Simulations (LES) is presented. The AGATE experiments have originally not been designed for CFD validation but to characterize different types of mixing grids. Nevertheless, the quality of the experimental data allows the quantitative comparison between measurement and calculation. The test section of the AGATE facility has been discretized for the LES calculation on 300 million control volumes by using a staggered grid approach on tetrahedral meshes. 20 days of CPU on 4600 cores of the HPC machine CURIE of the TGCC was necessary to calculate the statistics of the turbulent flow, in particular the mean velocity and the RMS of the turbulent fluctuations. The parallelism of Trio-U was tested up to 10,000 processor cores using strong scaling and has shown a good efficiency up to about 6000 cores, i.e., 40,000 control volumes per core. For various distances from the mixing grid, calculated horizontal profiles of the cross flow velocity and of the axial velocity are compared to measurements. It seems that the flow patterns directly downstream of the grid are insensitive to the used turbulence model. Inertia forces related to the

  13. Nonlinear dynamics and numerical uncertainties in CFD

    Science.gov (United States)

    Yee, H. C.; Sweby, P. K.

    1996-01-01

    The application of nonlinear dynamics to improve the understanding of numerical uncertainties in computational fluid dynamics (CFD) is reviewed. Elementary examples in the use of dynamics to explain the nonlinear phenomena and spurious behavior that occur in numerics are given. The role of dynamics in the understanding of long time behavior of numerical integrations and the nonlinear stability, convergence, and reliability of using time-marching, approaches for obtaining steady-state numerical solutions in CFD is explained. The study is complemented with spurious behavior observed in CFD computations.

  14. Computational System For Rapid CFD Analysis In Engineering

    Science.gov (United States)

    Barson, Steven L.; Ascoli, Edward P.; Decroix, Michelle E.; Sindir, Munir M.

    1995-01-01

    Computational system comprising modular hardware and software sub-systems developed to accelerate and facilitate use of techniques of computational fluid dynamics (CFD) in engineering environment. Addresses integration of all aspects of CFD analysis process, including definition of hardware surfaces, generation of computational grids, CFD flow solution, and postprocessing. Incorporates interfaces for integration of all hardware and software tools needed to perform complete CFD analysis. Includes tools for efficient definition of flow geometry, generation of computational grids, computation of flows on grids, and postprocessing of flow data. System accepts geometric input from any of three basic sources: computer-aided design (CAD), computer-aided engineering (CAE), or definition by user.

  15. Calculation of conversion coefficients for radiological protection against external radiation exposures

    International Nuclear Information System (INIS)

    Zankl, M.

    2001-01-01

    Calculations are essential for radiation protection practice because organ doses and effective doses cannot be measured directly. Conversion coefficients describe the numerical relationships of protection quantities and operational quantities. The latter can be measured in practical situations using suitable dosimeters. The conversion coefficients are calculated using radiation transport codes - usually based on Monte Carlo methods - that simulate the interactions of radiation with matter in computational models of the human body. A new generation of human body models, the so-called voxel models, are constructed from image data of real persons using suitable image processing systems, consequently, they represent the human anatomy more realistically than the so-called mathematical models. The numerical effects of realistic body anatomy on the calculated conversion coefficients can amount to 70% and more for external exposures. (orig.) [de

  16. Validation of a CFD code for Unsteady Flows with cyclic boundary Conditions

    International Nuclear Information System (INIS)

    Kim, Jong-Tae; Kim, Sang-Baik; Lee, Won-Jae

    2006-01-01

    Currently Lilac code is under development to analyze thermo-hydraulics of a high-temperature gas-cooled reactor (GCR). Interesting thermo-hydraulic phenomena in a nuclear reactor are usually unsteady and turbulent. The analysis of the unsteady flows by using a three dimension CFD code is time-consuming if the flow domain is very large. Hopefully, flow domains commonly encountered in the nuclear thermo-hydraulics is periodic. So it is better to use the geometrical characteristics in order to reduce the computational resources. To get the benefits from reducing the computation domains especially for the calculations of unsteady flows, the cyclic boundary conditions are implemented in the parallelized CFD code LILAC. In this study, the parallelized cyclic boundary conditions are validated by solving unsteady laminar and turbulent flows past a circular cylinder

  17. Some Aspects of Nonlinear Dynamics and CFD

    Science.gov (United States)

    Yee, Helen C.; Merriam, Marshal (Technical Monitor)

    1996-01-01

    The application of nonlinear dynamics to improve the understanding of numerical uncertainties in computational fluid dynamics (CFD) is reviewed. Elementary examples in the use of dynamics to explain the nonlinear phenomena and spurious behavior that occur in numerics are given. The role of dynamics in the understanding of long time behavior of numerical integrations and the nonlinear stability, convergence, and reliability of using time-marching approaches for obtaining steady-state numerical solutions in CFD is explained. The study is complemented with examples of spurious behavior observed in CFD computations.

  18. CFD for wind and tidal offshore turbines

    CERN Document Server

    Montlaur, Adeline

    2015-01-01

    The book encompasses novel CFD techniques to compute offshore wind and tidal applications. Computational fluid dynamics (CFD) techniques are regarded as the main design tool to explore the new engineering challenges presented by offshore wind and tidal turbines for energy generation. The difficulty and costs of undertaking experimental tests in offshore environments have increased the interest in the field of CFD which is used to design appropriate turbines and blades, understand fluid flow physical phenomena associated with offshore environments, predict power production or characterise offshore environments, amongst other topics.

  19. Error estimation for CFD aeroheating prediction under rarefied flow condition

    Science.gov (United States)

    Jiang, Yazhong; Gao, Zhenxun; Jiang, Chongwen; Lee, Chunhian

    2014-12-01

    Both direct simulation Monte Carlo (DSMC) and Computational Fluid Dynamics (CFD) methods have become widely used for aerodynamic prediction when reentry vehicles experience different flow regimes during flight. The implementation of slip boundary conditions in the traditional CFD method under Navier-Stokes-Fourier (NSF) framework can extend the validity of this approach further into transitional regime, with the benefit that much less computational cost is demanded compared to DSMC simulation. Correspondingly, an increasing error arises in aeroheating calculation as the flow becomes more rarefied. To estimate the relative error of heat flux when applying this method for a rarefied flow in transitional regime, theoretical derivation is conducted and a dimensionless parameter ɛ is proposed by approximately analyzing the ratio of the second order term to first order term in the heat flux expression in Burnett equation. DSMC simulation for hypersonic flow over a cylinder in transitional regime is performed to test the performance of parameter ɛ, compared with two other parameters, Knρ and MaṡKnρ.

  20. Parallel Resolved Open Source CFD-DEM: Method, Validation and Application

    Directory of Open Access Journals (Sweden)

    A. Hager

    2014-03-01

    Full Text Available In the following paper the authors present a fully parallelized Open Source method for calculating the interaction of immersed bodies and surrounding fluid. A combination of computational fluid dynamics (CFD and a discrete element method (DEM accounts for the physics of both the fluid and the particles. The objects considered are relatively big compared to the cells of the fluid mesh, i.e. they cover several cells each. Thus this fictitious domain method (FDM is called resolved. The implementation is realized within the Open Source framework CFDEMcOupling (www.cfdem.com, which provides an interface between OpenFOAM® based CFD-solvers and the DEM software LIGGGHTS (www.liggghts.com. While both LIGGGHTS and OpenFOAM® were already parallelized, only a recent improvement of the algorithm permits the fully parallel computation of resolved problems. Alongside with a detailed description of the method, its implementation and recent improvements, a number of application and validation examples is presented in the scope of this paper.

  1. CFD studies on thermal hydraulics of spallation targets

    International Nuclear Information System (INIS)

    Tak, N.I.; Batta, A.; Cheng, X.

    2005-01-01

    Full text of publication follows: Due to the fast advances in computer hardware as well as software in recent years, more and more interests have been aroused to use computational fluid dynamics (CFD) technology in nuclear engineering and designs. During recent many years, Forschungszentrum Karlsruhe (FZK) has been actively involved in the thermal hydraulic analysis and design of spallation targets. To understand the thermal hydraulic behaviors of spallation targets very detailed simulations are necessary because of their complex geometries, complicated boundary conditions such as spallation heat distributions, and very strict design limits. A CFD simulation is believed to be the best for this purpose even though the validation of CFD codes are not perfectly completed yet in specific topics like liquid metal heat transfer. The research activities on three spallation targets (i.e., MEGAPIE, TRADE, and XADS targets) are currently very active in Europe in order to consolidate the European ADS road-map. In the thermal hydraulics point of view, two kinds of the research activities, i.e., (1) numerical design and (2) experimental work, are required to achieve the objectives of these targets. It should be noted that CFD studies play important role on both kinds of two activities. A preliminary design of a target can be achieved by sophisticated CFD analysis and pre-and-post analyses of an experimental work using a CFD code help the design of the test section of the experiment as well as the analysis of the experimental results. The present paper gives an overview about the recent CFD studies relating to thermal hydraulics of the spallation targets recently involved in FZK. It covers numerical design studies as well as CFD studies to support experimental works. The CFX code has been adopted for the studies. Main recent results for the selected examples performed by FZK are presented and discussed with their specific lessons learned. (authors)

  2. Prediction of leakage and rotordynamic coefficients for the circumferential-groove pump seal using CFD analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Ho; Ha, Tae Woong [Gachon University, Seongnam (Korea, Republic of)

    2016-05-15

    The circumferential-groove seal is commonly used in various turbopumps to reduce leakage. The main goal of this paper is to develop the method of three-dimensional CFD analysis for determining leakage and rotordynamic coefficients of the circumferential-groovepump seal. A relative coordinate system was defined for steady-state simulation to calculate the velocity and pressure distributions of the seal clearance at each rotor whirl speed. Instead of setting the inlet and outlet pressures as the boundary conditions in the three dimensional CFD analysis, as it is more commonly done, we used the inlet velocity and outlet pressure obtained from a preliminary two dimensional CFD analysis. For prediction leakage, the presented analysis shows improvement from the bulk-flow model analysis. For the prediction of rotordynamic coefficients of K, k and C, the presented analysis provides results in closer agreement with the experimental values than those of the bulk-flow model analysis at several rotor speeds.

  3. A computer code for the prediction of mill gases and hot air distribution between burners sections as input parameters for 3D CFD furnace calculation

    International Nuclear Information System (INIS)

    Tucakovic, Dragan; Zivanovic, Titoslav; Beloshevic, Srdjan

    2006-01-01

    Current computer technology development enables application of powerful software packages that can provide a reliable insight into real operating conditions of a steam boiler in the Thermal Power Plant. Namely, an application of CFD code to the 3D analysis of combustion and heat transfer in a furnace provides temperature, velocity and concentration fields in both cross sectional and longitudinal planes of the observed furnace. In order to obtain reliable analytical results, which corresponds to real furnace conditions, it is necessary to accurately predict a distribution of mill gases and hot air between burners' sections, because these parameters are input values for the furnace 3D calculation. Regarding these tasks, the computer code for the prediction of mill gases and hot air distribution has been developed at the Department for steam boilers of the Faculty of Mechanical Engineering in Belgrade. The code is based on simultaneous calculations of material and heat balances for fan mill and air tracts. The aim of this paper is to present a methodology of performed calculations and results obtained for the steam boiler furnace of 350 MWe Thermal Power Plant equipped with eight fan mills. Key words: mill gases, hot air, aerodynamic calculation, air tract, mill tract.

  4. CFD and FEM modeling of PPOOLEX experiments

    Energy Technology Data Exchange (ETDEWEB)

    Paettikangas, T.; Niemi, J.; Timperi, A. (VTT Technical Research Centre of Finland (Finland))

    2011-01-15

    Large-break LOCA experiment performed with the PPOOLEX experimental facility is analysed with CFD calculations. Simulation of the first 100 seconds of the experiment is performed by using the Euler-Euler two-phase model of FLUENT 6.3. In wall condensation, the condensing water forms a film layer on the wall surface, which is modelled by mass transfer from the gas phase to the liquid water phase in the near-wall grid cell. The direct-contact condensation in the wetwell is modelled with simple correlations. The wall condensation and direct-contact condensation models are implemented with user-defined functions in FLUENT. Fluid-Structure Interaction (FSI) calculations of the PPOOLEX experiments and of a realistic BWR containment are also presented. Two-way coupled FSI calculations of the experiments have been numerically unstable with explicit coupling. A linear perturbation method is therefore used for preventing the numerical instability. The method is first validated against numerical data and against the PPOOLEX experiments. Preliminary FSI calculations are then performed for a realistic BWR containment by modeling a sector of the containment and one blowdown pipe. For the BWR containment, one- and two-way coupled calculations as well as calculations with LPM are carried out. (Author)

  5. Modelación CFD de casos básicos de convección en ambientes cerrados: Necesidades de principiantes en CFD para adquirir habilidades y confianza en la modelación CFD

    Directory of Open Access Journals (Sweden)

    Magdalena Cortés

    2014-01-01

    Full Text Available La predicción de patrones de flujo de aire, velocidad, temperatura, humedad y concentración de contaminantes son requeridos para el diseño de ambientes interiores saludables y confortables. La Dinámica de Fluidos Computacional (CFD es la técnica más avanzada para modelar y predecir los flujos de aire en ambientes cerrados. Sin embargo, los principales errores en los modelos CFD y en sus resultados están relacionados con el factor humano. Los principiantes en modelación CFD no cuentan con las habilidades, experiencia y juicio ingenieril para generar modelos robustos y confiables. Este proceso no es intuitivo y los nuevos usuarios necesitan orientación. Este artículo busca proveer información más completa sobre la modelación CFD de casos básicos de convección natural, forzados y mixtos que permitirán a los nuevos usuarios adquirir las habilidades y confianza. La modelación CFD incluye la generación de malla, definición de criterios de convergencia y factores de relajación, y la evaluación de modelos de turbulencia para cada caso. Los resultados muestran que es necesaria la experiencia de los usuarios en cada paso de la modelación CFD, incluso para casos simples de convección.

  6. CFD simulation of hydrogen mixing and mitigation by means of passive auto-catalytic recombiners

    International Nuclear Information System (INIS)

    Kelm, S.; Reinecke, E-A.; Jahn, W.; Allelein, H-J.

    2011-01-01

    Modeling of passive auto-catalytic recombiners (PARs) operation in containment geometries involves a large variety of scales; thus, a CFD calculation resolving all these scales would be much too expensive. Therefore, the mechanistic PAR model REKO-DIREKT, developed at Forschungszentrum Juelich, has been coupled with the commercial CFD code ANSYS CFX in order to simulate PAR operation as well as the induced flow and transport phenomena. Based on a short introduction of REKO-DIREKT, its interface to CFX and the explicit coupling scheme is discussed. The paper is finalized by a first demonstration of simulation capabilities on the basis of the ThAI PAR-4 experiment (Becker Technologies GmbH, Eschborn, Germany). (author)

  7. Francis full-load surge mechanism identified by unsteady 2-phase CFD

    Energy Technology Data Exchange (ETDEWEB)

    Doerfler, P K; Keller, M; Braun, O, E-mail: peter.doerfler@andritz.co [R and D Department, Andritz Hydro Ltd., Zurich (Switzerland)

    2010-08-15

    Francis turbines may produce spontaneous pulsations of pressure and output power when operating at very high discharge. In such cases there is a cavitating central vortex in the draft tube with variable cavity volume V{sub c}. Until today, researchers agree that the main destabilizing agent is the so-called mass flow gain factor, defined as the derivative of cavity volume by the local discharge. Recent studies about 1D high-load stability analysis assumed that the mass-flow gain factor obtained from steady-state vortex data acts on the transient discharge downstream of the cavity. There are however good reasons to question this assumption. Most strikingly, the direct cause of the mass flow gain effect is the increase of swirl produced at the runner exit and hence upstream, not downstream of the cavity. To enhance the reliability of full-load stability predictions, the authors directly investigated the vortex dynamics. The development of the transient cavitating flow in the draft tube was simulated by means of unsteady 2-phase CFD. CFD work started with 1-phase calculations as presented by other authors. This was then extended to a more realistic 2-phase calculation. To contain the computing time within acceptable limits, given the very fine mesh and short time step required, the simulation domain was restricted to the draft tube and, at the same time, the problem was reduced to a basically 2-dimensional rotationally symmetric case. The response of the cavitating draft tube flow to a time-dependent inflow and time-dependent pressure at the draft tube exit was simulated. The results were input to a statistical identification procedure to check possible 1D transient models and find representative parameter values in the sense of a best fit between 1D model and CFD result. As we had suspected, the conventional vortex model with mass flow gain controlled by downstream discharge is not compatible with direct simulation and needs to be modified. The CFD results correspond

  8. Development of CFD fire models for deterministic analyses of the cable issues in the nuclear power plant

    International Nuclear Information System (INIS)

    Lin, C.-H.; Ferng, Y.-M.; Pei, B.-S.

    2009-01-01

    Additional fire barriers of electrical cables are required for the nuclear power plants (NPPs) in Taiwan due to the separation requirements of Appendix R to 10 CFR Part 50. The risk-informed fire analysis (RIFA) may provide a viable method to resolve these fire barrier issues. However, it is necessary to perform the fire scenario analyses so that RIFA can quantitatively determine the risk related to the fire barrier wrap. The CFD fire models are then proposed in this paper to help the RIFA in resolving these issues. Three typical fire scenarios are selected to assess the present CFD models. Compared with the experimental data and other model's simulations, the present calculated results show reasonable agreements, rendering that present CFD fire models can provide the quantitative information for RIFA analyses to release the cable wrap requirements for NPPs

  9. Application of CFD methods in research of SCWR thermo-hydraulics

    International Nuclear Information System (INIS)

    Zeng Xiaokang; Li Yongliang; Yan Xiao; Xiao Zejun; Huang Yanping

    2013-01-01

    The CFD method has been an important tool in the research of SCWR thermo- hydraulics. Currently, the CFD methods uses commonly the subcritical turbulence models, which can not accurately simulate the gravity and thermal expansion acceleration effect, and CFD numerical method is not applicable when the heat flux is large. The paper summarizes the application status of the CFD methods in the research of SCWR thermo-hydraulics in RETH. (authors)

  10. Supercritical water: On a road from CFD to NPP simulations

    International Nuclear Information System (INIS)

    Rintala, Lauri; Danielyan, Davit; Salomaa, Rainer

    2010-01-01

    The Fission and Radiation Physics Group at the Aalto University is contributing to the Finnish SCWR activities within the GEN4FIN-network. Our research involves reactor core thermal hydraulics, and in particular, heat transfer phenomena in supercritical water including both theoretical studies and simulations with APROS and OpenFOAM. APROS is a software applicable to full-scale power plant simulations and OpenFOAM an open source CFD code. The complicated heat transfer in the supercritical region is a very challenging problem for the design of SCWRs and their safety assessment. The steam tables of APROS have been extended to the supercritical region and their functionality has been tested with, e.g. blowdown simulations where the transient is rapid, hence mainly challenging for numerical stability whereas heat transfer has negligible effects. Numerous different heat correlations for supercritical water have been suggested , but simulations of benchmark experiments have shown that for instance fuel clad temperatures generally cannot be described sufficiently accurately. This discrepancy has been encountered in several process simulation codes. The largest errors occur near the pseudo critical line, during the heat transfer deterioration. It turns out that the physics in supercritical water is clearly more intricate than in ordinary boiling heat transfer where rather satisfactory heat transfer correlations are available. Full 3D CFD calculations allow a better description of various aspects of heat transfer in the supercritical region, i.e., effects arising from turbulence , buoyancy , varying material properties etc. On the other hand, CFD calculations are not feasible for plant-scale simulations. We have selected some simplified geometries and parameter ranges to study SCW heat transfer in a reactor. Old experiments have been calculated with satisfactory results with OpenFOAM to check its validity. A steady state case of heat transfer in a circular pipe with upward

  11. Results from a CFD reference study into the modelling of heat and smoke transport by different CFD-practitioners

    NARCIS (Netherlands)

    Loomans, M.G.L.C.; Lemaire, A.D.; Plas, van der M.

    2009-01-01

    The paper describes results from a reference study that focuses on the application of the Computational Fluid Dynamics (CFD-) technique for heat and smoke transport in practice. Goal of the study is to obtain insight into the amount and causes of the spread of CFD-results when applied by different

  12. CFD Modelling of Abdominal Aortic Aneurysm on Hemodynamic Loads Using a Realistic Geometry with CT

    Directory of Open Access Journals (Sweden)

    Eduardo Soudah

    2013-01-01

    Full Text Available The objective of this study is to find a correlation between the abdominal aortic aneurysm (AAA geometric parameters, wall stress shear (WSS, abdominal flow patterns, intraluminal thrombus (ILT, and AAA arterial wall rupture using computational fluid dynamics (CFD. Real AAA 3D models were created by three-dimensional (3D reconstruction of in vivo acquired computed tomography (CT images from 5 patients. Based on 3D AAA models, high quality volume meshes were created using an optimal tetrahedral aspect ratio for the whole domain. In order to quantify the WSS and the recirculation inside the AAA, a 3D CFD using finite elements analysis was used. The CFD computation was performed assuming that the arterial wall is rigid and the blood is considered a homogeneous Newtonian fluid with a density of 1050 kg/m3 and a kinematic viscosity of 4×10-3 Pa·s. Parallelization procedures were used in order to increase the performance of the CFD calculations. A relation between AAA geometric parameters (asymmetry index (β, saccular index (γ, deformation diameter ratio (χ, and tortuosity index (ε and hemodynamic loads was observed, and it could be used as a potential predictor of AAA arterial wall rupture and potential ILT formation.

  13. Application of CFD technique for HYFLEX aerodynamic design

    OpenAIRE

    Yamamoto, Yukimitsu; Watanabe, Shigeya; Ishiguro, Mitsuo; Ogasawara, Ko; 山本 行光; 渡辺 重哉; 石黒 満津夫; 小笠原 宏

    1994-01-01

    An overview of the application of Computational Fluid Dynamics (CFD) technique for the HYFLEX (Hypersonic Flight Experiment) aerodynamic design by using the numerical simulation codes in the supersonic and hypersonic speed ranges is presented. Roles of CFD required to make up for the short term of development and small amount of the wind tunnel test cases, application in the HYFLEX aerodynamic design and their application methods are described. The procedure of CFD code validation by the expe...

  14. Implementation into a CFD code of neutron kinetics and fuel pin models for nuclear reactor transient analyses

    International Nuclear Information System (INIS)

    Chen Zhao; Chen, Xue-Nong; Rineiski, Andrei; Zhao Pengcheng; Chen Hongli

    2014-01-01

    Safety analysis is an important tool for justifying the safety of nuclear reactors. The traditional method for nuclear reactor safety analysis is performed by means of system codes, which use one-dimensional lumped-parameter method to model real reactor systems. However, there are many multi-dimensional thermal-hydraulic phenomena cannot be predicated using traditional one-dimensional system codes. This problem is extremely important for pool-type nuclear systems. Computational fluid dynamics (CFD) codes are powerful numerical simulation tools to solve multi-dimensional thermal-hydraulics problems, which are widely used in industrial applications for single phase flows. In order to use general CFD codes to solve nuclear reactor transient problems, some additional models beyond general ones are required. Neutron kinetics model for power calculation and fuel pin model for fuel pin temperature calculation are two important models of these additional models. The motivation of this work is to develop an advance numerical simulation method for nuclear reactor safety analysis by implementing neutron kinetics model and fuel pin model into general CFD codes. In this paper, the Point Kinetics Model (PKM) and Fuel Pin Model (FPM) are implemented into a general CFD code FLUENT. The improved FLUENT was called as FLUENT/PK. The mathematical models and implementary method of FLUENT/PK are descripted and two demonstration application cases, e.g. the unprotected transient overpower (UTOP) accident of a Liquid Metal cooled Fast Reactor (LMFR) and the unprotected beam overpower (UBOP) accident of an Accelerator Driven System (ADS), are presented. (author)

  15. CFD Modeling of Free-Piston Stirling Engines

    Science.gov (United States)

    Ibrahim, Mounir B.; Zhang, Zhi-Guo; Tew, Roy C., Jr.; Gedeon, David; Simon, Terrence W.

    2001-01-01

    NASA Glenn Research Center (GRC) is funding Cleveland State University (CSU) to develop a reliable Computational Fluid Dynamics (CFD) code that can predict engine performance with the goal of significant improvements in accuracy when compared to one-dimensional (1-D) design code predictions. The funding also includes conducting code validation experiments at both the University of Minnesota (UMN) and CSU. In this paper a brief description of the work-in-progress is provided in the two areas (CFD and Experiments). Also, previous test results are compared with computational data obtained using (1) a 2-D CFD code obtained from Dr. Georg Scheuerer and further developed at CSU and (2) a multidimensional commercial code CFD-ACE+. The test data and computational results are for (1) a gas spring and (2) a single piston/cylinder with attached annular heat exchanger. The comparisons among the codes are discussed. The paper also discusses plans for conducting code validation experiments at CSU and UMN.

  16. GTRF Calculations Using Hydra-TH (L3 Milestone THM.CFD.P5.05)

    International Nuclear Information System (INIS)

    Bakosi, Jozsef; Christon, Mark A.; Francois, Marianne M.; Lowrie, Robert B.; Nourgaliev, Robert

    2012-01-01

    This report describes the work carried out for completion of the Thermal Hydraulics Methods (THM) Level 3 Milestone THM.CFD.P5.05 for the Consortium for Advanced Simulation of Light Water Reactors (CASL). A series of body-fitted computational meshes have been generated by Numeca's Hexpress/Hybrid, a.k.a. 'Spider', meshing technology for the V5H 3 x 3 and 5 x 5 rod bundle geometries and subsequently used to compute the fluid dynamics of grid-to-rod fretting (GTRF). Spider is easy to use, fast, and automatically generates high-quality meshes for extremely complex geometries, required for the GTRF problem. Hydra-TH has been used to carry out large-eddy simulations on both 3 x 3 and 5 x 5 geometries, using different mesh resolutions. The results analyzed show good agreement with Star-CCM+ simulations and experimental data.

  17. Gradient Calculation Methods on Arbitrary Polyhedral Unstructured Meshes for Cell-Centered CFD Solvers

    Science.gov (United States)

    Sozer, Emre; Brehm, Christoph; Kiris, Cetin C.

    2014-01-01

    A survey of gradient reconstruction methods for cell-centered data on unstructured meshes is conducted within the scope of accuracy assessment. Formal order of accuracy, as well as error magnitudes for each of the studied methods, are evaluated on a complex mesh of various cell types through consecutive local scaling of an analytical test function. The tests highlighted several gradient operator choices that can consistently achieve 1st order accuracy regardless of cell type and shape. The tests further offered error comparisons for given cell types, leading to the observation that the "ideal" gradient operator choice is not universal. Practical implications of the results are explored via CFD solutions of a 2D inviscid standing vortex, portraying the discretization error properties. A relatively naive, yet largely unexplored, approach of local curvilinear stencil transformation exhibited surprisingly favorable properties

  18. Calculations and analysis of the radiation protection of PET/CT Center

    International Nuclear Information System (INIS)

    Ivanova, S.; Artinyan, A.

    2015-01-01

    Positron Emission Tomography (PET) has been available in number of centers for more than 25 years, but its use was not wide spread until 10 years ago. In Bulgarian PET/CT was installed for the first time in 2009 in Nuclear Medicine Department in University Hospital St. Marina in Varna, Bulgaria. As a physicists the aim for us was to consider and calculate the shielding so that to protect the people and the staff. The purpose of this paper is calculating and analysis of the radiation protection and shielding of Nuclear Medicine Center including PET/CT center situated in University Hospital St. Marina in Varna, Bulgaria. Following the Recommendation of International Commission of Radiation Protection (ICRP) Report 60, Report 73, American Association of Physics in Medicine (AAPM) Task Group 108: PET and PET/CT Shielding Requirements, Medical Physics, DIN 6844-3, Installation of Nuclear Medicine; Radiation protection calculation and the Bulgarian regulations in NM, the new Department was made. The design of the Existing Department was renovated following the requirements for PET/CT Center. The shielding was calculated for imaging room as well as the uptake room, resting room, the PET control room, places above and under the facility, patient WCs and other surrounding laboratories and stuff cabinets. The radiotracer used for the examinations is fluoro-2-desixyglucose (FDG). FDG is labeled with F-18, whose time of flight is only 109min, but it is positron emitting. The energy of annihilation is 511keV. The aim was achieved. The Department was opened. It is working now with about 15 patients every day. The dose rates measured with personal TLD’s for the last 5 years for the stuff are under 3mSv. As the average dose is around 1mSv, and the doses over 1mSv are only for nurses who injected the FDG. (authors)

  19. Review of the radiation protection calculations for the encapsulation plant

    International Nuclear Information System (INIS)

    Ranta-aho, A.

    2008-09-01

    The radiation protection calculations of the encapsulation plant have been carried out with the MCNP5 Monte Carlo code. The focus of the study has been in the parts of the encapsulation plant where the spent fuel is handled after discharge from the transportation casks i.e. the fuel handling cell, the fuel drying station, the canister transfer corridor, the welding chamber, the weld inspection room, the canister buffer storage and the canister lift. The protection against radiation hazard has been mainly designed with thick concrete walls. Additionally, the entrances to the rooms with shielding requirements have been equipped with mazes. The present design excludes doors with shielding properties. The aim of this work was to verify and evaluate the necessary wall thicknesses and the functioning of the mazes in the current design. The calculations verified that for the most parts of the facility, the currently designed walls thicknesses provide adequate protection against radiation from the different spent fuel assembly configurations. Some corrective actions however seem necessary in order to stay clearly below desired radiation limits. For the most parts the functioning of the mazes was inadequate. In some of the cases a different design of the maze will be sufficient action but in some cases the radiation protection can only be secured by heavy doors for practical reasons. (orig.)

  20. The Dalles Dam, Columbia River: Spillway Improvement CFD Study

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Chris B.; Richmond, Marshall C.; Serkowski, John A.

    2006-06-01

    This report documents development of computational fluid dynamics (CFD) models that were applied to The Dalles spillway for the US Army Corps of Engineers, Portland District. The models have been successfully validated against physical models and prototype data, and are suitable to support biological research and operations management. The CFD models have been proven to provide reliable information in the turbulent high-velocity flow field downstream of the spillway face that is typically difficult to monitor in the prototype. In addition, CFD data provides hydraulic information throughout the solution domain that can be easily extracted from archived simulations for later use if necessary. This project is part of an ongoing program at the Portland District to improve spillway survival conditions for juvenile salmon at The Dalles. Biological data collected at The Dalles spillway have shown that for the original spillway configuration juvenile salmon passage survival is lower than desired. Therefore, the Portland District is seeking to identify operational and/or structural changes that might be implemented to improve fish passage survival. Pacific Northwest National Laboratory (PNNL) went through a sequence of steps to develop a CFD model of The Dalles spillway and tailrace. The first step was to identify a preferred CFD modeling package. In the case of The Dalles spillway, Flow-3D was as selected because of its ability to simulate the turbulent free-surface flows that occur downstream of each spilling bay. The second step in development of The Dalles CFD model was to assemble bathymetric datasets and structural drawings sufficient to describe the dam (powerhouse, non-overflow dam, spillway, fish ladder entrances, etc.) and tailrace. These datasets are documented in this report as are various 3-D graphical representations of The Dalles spillway and tailrace. The performance of the CFD model was then validated for several cases as the third step. The validated model

  1. Analysis of heat transfer in different CPC solar collectors: A CFD approach

    International Nuclear Information System (INIS)

    Antonelli, M.; Francesconi, M.; Di Marco, P.; Desideri, U.

    2016-01-01

    Highlights: • We made a CFD simulation with a validated model. • We analyzed the influence of the geometrical parameters of the collector. • We established a correspondence between the Nusselt number and the characteristic dimensions and parameters of the collector. - Abstract: In this paper a methodology is proposed to estimate thermal heat losses inside compound parabolic collectors (CPC) to be used in designing and validating new collectors' concepts and materials. CFD simulations were carried out on different CPCs, taking into account the effective working conditions and the presence of radiative heat transfer as well as the absence of adiabatic walls. The CFD model was validated considering a previous work reported in literature. The results were employed to develop some correlations by interpolation of numerical data, to express the Nusselt number on the receiver. We used these correlations to calculate heat losses of the receiver and to show the influence of different parameters such as the shape of receiver itself, tilt angle and concentration ratio. The variation of terms of the correlation as a function of characteristic length and concentration was studied. These results might be employed for a preliminary estimation procedure of a CPC collector efficiency and to propose sizing criteria of general validity for this class of devices.

  2. Tip studies using CFD and comparison with tip loss models

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver; Johansen, J.

    2004-01-01

    The flow past a rotating LM8.2 blade equipped with two different tips are computed using CFD. The different tip flows are analysed and a comparison with two different tip loss models is made. Keywords: tip flow, aerodynamics, CFD......The flow past a rotating LM8.2 blade equipped with two different tips are computed using CFD. The different tip flows are analysed and a comparison with two different tip loss models is made. Keywords: tip flow, aerodynamics, CFD...

  3. Application of computational fluid dynamics (CFD) to nuclear applications

    International Nuclear Information System (INIS)

    Brewster, R. A.; Jonnavithula, S.; Rizwan-Uddin; Rock, D. T.; Weber, D. P.; Wei, T. Y. C.

    1999-01-01

    Detailed analysis of a quarter channel was performed using VIPRE and CFX. Results show that VIPRE and CFX agree closely in both cross-sectionally averaged axial temperature and cross-sectionally averaged axial velocity profiles. Detailed temperature distributions in the radial direction over 1mm from the clad surface towards the center of the channel were calculated using CFX, showing significant local variation. This information can be used for example, to determine if this temperature will lead to bubble nucleation. Quarter subassembly calculations were made with both VIPRE and STAR-CD. Comparison between the solutions show that the two codes yield very similar solutions under comparable conditions. However, the STAR-CD CFD calculation provides the analyst with much more detailed flow and temperature distributions than can be predicted by a one-dimensional code such as VIPRE. In addition, a 60 million cell one-eighth reactor core calculation was made using STAR-CD. This analysis showed the importance of accurately predicting the flow and temperature fields in all assemblies simultaneously with modern parallel processing technology, practical turnaround for these types of calculation can be obtained

  4. Tracer dispersion - experiment and CFD

    International Nuclear Information System (INIS)

    Zitny, R.

    2004-01-01

    Description of tracer distribution by means of dispersion models is a method successfully used in process engineering for fifty years. Application of dispersion models in reactor engineering for characterization of flows in column apparatus, heat exchangers, etc. is summarized and experimental tracer techniques as well as CFD methods for dispersion coefficients evaluation are discussed. Possible extensions of thermal axial dispersion model (ADM) and a core-wall ADM model suitable for description of tracer dispersion in laminar flows are suggested as well as CFD implementation as 1D finite elements. (author)

  5. Retooling CFD for hypersonic aircraft

    Science.gov (United States)

    Dwoyer, Douglas L.; Kutler, Paul; Povinelli, Louis A.

    1987-01-01

    The CFD facility requirements of hypersonic aircraft configuration design development are different from those thus far employed for reentry vehicle design, because (1) the airframe and the propulsion system must be fully integrated to achieve the desired performance; (2) the vehicle must be reusable, with minimum refurbishment requirements between flights; and (3) vehicle performance must be optimized for a wide range of Mach numbers. An evaluation is presently made of flow resolution within shock waves, transition and turbulence phenomenon tractability, chemical reaction modeling, and hypersonic boundary layer transition, with state-of-the-art CFD.

  6. Validation of NEPTUNE-CFD two-phase flow models using experimental data

    International Nuclear Information System (INIS)

    Perez-Manes, Jorge; Sanchez Espinoza, Victor Hugo; Bottcher, Michael; Stieglitz, Robert; Sergio Chiva Vicent

    2014-01-01

    This paper deals with the validation of the two-phase flow models of the CFD code NEPTUNE-CFD using experimental data provided by the OECD BWR BFBT and PSBT Benchmark. Since the two-phase models of CFD codes are extensively being improved, the validation is a key step for the acceptability of such codes. The validation work is performed in the frame of the European NURISP Project and it was focused on the steady state and transient void fraction tests. The influence of different NEPTUNE-CFD model parameters on the void fraction prediction is investigated and discussed in detail. Due to the coupling of heat conduction solver SYRTHES with NEPTUNE-CFD, the description of the coupled fluid dynamics and heat transfer between the fuel rod and the fluid is improved significantly. The averaged void fraction predicted by NEPTUNE-CFD for selected PSBT and BFBT tests is in good agreement with the experimental data. Finally, areas for future improvements of the NEPTUNE-CFD code were identified, too. (authors)

  7. Development of a GUI Based Front End for Open Source CFD Program, OpenFOAM

    International Nuclear Information System (INIS)

    Han, Samhee; Lee, Youngjin; Kim, Hyongchol; Park, Sunbyung; Kim, Hyunjik

    2013-01-01

    OpenFOAM is sorely lacking in user friendliness as it runs in console mode under Li nux. Run F OAM was developed to greatly simplify the task of running an OpenFOAM calculation under Windows OS. Run F OAM was written using Delphi object pascal language, and GLScene package was used for the 3D graphics. Verification of Run F OAM was carried out by performing some OpenFOAM CFD calculations provided in OpenFOAM package, and these showed that the use of Run F OAM is simple whilst providing sufficient allowances in user modifications. Run F oam, a GUI based front end program to simplify running Open Foam CFD cases, has been developed. By incorporating numerous GUI in the program, Run F oam has demonstrated that running an Open Foam case can be easily accomplished. There is a potential for further development as the Open Foam has the great advantage of being free to develop and to use. There is also a potential to couple or interface the Open Foam with the systems analysis code such as Relap5

  8. Computational Fluid Dynamics (CFD) applications in rocket propulsion analysis and design

    Science.gov (United States)

    Mcconnaughey, P. K.; Garcia, R.; Griffin, L. W.; Ruf, J. H.

    1993-01-01

    Computational Fluid Dynamics (CFD) has been used in recent applications to affect subcomponent designs in liquid propulsion rocket engines. This paper elucidates three such applications for turbine stage, pump stage, and combustor chamber geometries. Details of these applications include the development of a high turning airfoil for a gas generator (GG) powered, liquid oxygen (LOX) turbopump, single-stage turbine using CFD as an integral part of the design process. CFD application to pump stage design has emphasized analysis of inducers, impellers, and diffuser/volute sections. Improvements in pump stage impeller discharge flow uniformity have been seen through CFD optimization on coarse grid models. In the area of combustor design, recent CFD analysis of a film cooled ablating combustion chamber has been used to quantify the interaction between film cooling rate, chamber wall contraction angle, and geometry and their effects of these quantities on local wall temperature. The results are currently guiding combustion chamber design and coolant flow rate for an upcoming subcomponent test. Critical aspects of successful integration of CFD into the design cycle includes a close-coupling of CFD and design organizations, quick turnaround of parametric analyses once a baseline CFD benchmark has been established, and the use of CFD methodology and approaches that address pertinent design issues. In this latter area, some problem details can be simplified while retaining key physical aspects to maintain analytical integrity.

  9. GTRF Calculations Using Hydra-TH (L3 Milestone THM.CFD.P5.05)

    Energy Technology Data Exchange (ETDEWEB)

    Bakosi, Jozsef [Los Alamos National Laboratory; Christon, Mark A. [Los Alamos National Laboratory; Francois, Marianne M. [Los Alamos National Laboratory; Lowrie, Robert B. [Los Alamos National Laboratory; Nourgaliev, Robert [Los Alamos National Laboratory

    2012-09-05

    This report describes the work carried out for completion of the Thermal Hydraulics Methods (THM) Level 3 Milestone THM.CFD.P5.05 for the Consortium for Advanced Simulation of Light Water Reactors (CASL). A series of body-fitted computational meshes have been generated by Numeca's Hexpress/Hybrid, a.k.a. 'Spider', meshing technology for the V5H 3 x 3 and 5 x 5 rod bundle geometries and subsequently used to compute the fluid dynamics of grid-to-rod fretting (GTRF). Spider is easy to use, fast, and automatically generates high-quality meshes for extremely complex geometries, required for the GTRF problem. Hydra-TH has been used to carry out large-eddy simulations on both 3 x 3 and 5 x 5 geometries, using different mesh resolutions. The results analyzed show good agreement with Star-CCM+ simulations and experimental data.

  10. CFD simulation analysis and validation for CPR1000 pressurized water reactor

    International Nuclear Information System (INIS)

    Zhang Mingqian; Ran Xiaobing; Liu Yanwu; Yu Xiaolei; Zhu Mingli

    2013-01-01

    Background: With the rapid growth in the non-nuclear area for industrial use of Computational fluid dynamics (CFD) which has been accompanied by dramatically enhanced computing power, the application of CFD methods to problems relating to Nuclear Reactor Safety (NRS) is rapidly accelerating. Existing research data have shown that CFD methods could predict accurately the pressure field and the flow repartition in reactor lower plenum. But simulations for the full domain of the reactor have not been reported so far. Purpose: The aim is to determine the capabilities of the codes to model accurately the physical phenomena which occur in the full reactor vessel. Methods: The flow field of the CPR1000 reactor which is associated with a typical pressurized water reactor (PWR) is simulated by using ANSYS CFX. The pressure loss in reactor pressure vessel, the hydraulic loads of guide tubes and support columns, and the bypass flow of head dome were obtained by calculations for the full domain of the reactor. The results were validated by comparing with the determined reference value of the operating nuclear plant (LingAo nuclear plant), and the transient simulation was conducted in order to better understand the flow in reactor pressure vessel. Results: It was shown that the predicted pressure loss with CFD code was slightly different with the determined value (10% relative deviation for the total pressure loss), the hydraulic loads were less than the determined value with maximum relative deviation 50%, and bypass flow of head dome was approximately the same with determined value. Conclusion: This analysis practice predicts accurately the physical phenomena which occur in the full reactor vessel, and can be taken as a guidance for the nuclear plant design development and improve our understanding of reactor flow phenomena. (authors)

  11. Study of Laminar Flame 2-D Scalar Values at Various Fuel to Air Ratios Using an Imaging Fourier-Transform Spectrometer and 2-D CFD Analysis

    Science.gov (United States)

    2013-03-01

    Role of flow visualization in the development of UNICORN , Journal of Visualization 2000, Vol. 2, 257-272. [10] Gross, K. C.; Tremblay, P.; Bradley...NASA- Glenn’s Chemical Equilibrium with Applications (CEA) program. UNICORN CFD predictions were in excellent agreement with CEA calculations at...49 Appendix A – UNICORN CFD Inputs and Instruction .....................................................50 Appendix B – NASA-Glenn

  12. Pressure loss coefficient evaluation based on CFD analysis for simple geometries and PWR reactor vessel without geometry simplification

    International Nuclear Information System (INIS)

    Ko II, B.; Park, J. P.; Jeong, J. H.

    2008-01-01

    Nuclear vendors and utilities perform lots of simulations and analyses in order to ensure the safe operation of nuclear power plants (NPPs). In general, the simulations are carried out using vendor-specific design codes and best-estimate system analysis codes and most of them were developed based on 1-dimensional lumped parameter models. These thermal-hydraulic system analysis codes require user input for pressure loss coefficient, k-factor; since they numerically solve Euler-equation. In spite of its high impact on the safety analysis results, there has not been good validation method for the selection of loss coefficient. During the past decade, however; computers, parallel computation methods, and 3-dimensional computational fluid dynamics (CFD) codes have been dramatically enhanced. It is believed to be beneficial to take advantage of advanced commercial CFD codes in safety analysis and design of NPP5. The present work aims to validate pressure loss coefficient evaluation for simple geometries and k-factor calculation for PWR based on CFD. The performances of standard k-ε model, RNG k-ε model, Reynolds stress model (RSM) on the simulation of pressure drop for simple geometry such as, or sudden-expansion, and sudden-contraction are evaluated. The calculated value was compared with pressure loss coefficient in handbook of hydraulic resistance. Then the present work carried out analysis for flow distribution in downcomer and lower plenum of Korean standard nuclear power plants (KSNPs) using STAR-CD. The lower plenum geometry of a PWR is very complicated since there are so many reactor internals, which hinders in CFD analysis for real reactor geometry up to now. The present work takes advantage of 3D CAD model so that real geometry of lower plenum is used. The results give a clear figure about flow fields in the reactor vessel, which is one of major safety concerns. The calculated pressure drop across downcomer and lower plenum appears to be in good agreement

  13. CFD validation experiments for hypersonic flows

    Science.gov (United States)

    Marvin, Joseph G.

    1992-01-01

    A roadmap for CFD code validation is introduced. The elements of the roadmap are consistent with air-breathing vehicle design requirements and related to the important flow path components: forebody, inlet, combustor, and nozzle. Building block and benchmark validation experiments are identified along with their test conditions and measurements. Based on an evaluation criteria, recommendations for an initial CFD validation data base are given and gaps identified where future experiments could provide new validation data.

  14. CFD analysis of the hydrodynamic and cavitation performances of modified NACA 4418 hydrofoil

    International Nuclear Information System (INIS)

    Markov, Zoran; Popovski, Predrag; Lipej, Andrej

    2001-01-01

    The paper presents the analysis of the possibilities of using Computational Fluid Dynamics technology for calculating of the flow parameters in a cavitation tunnel. Different turbulence models are used to perform the calculations. Comparison of the results from the experimental work and the CFD-TASC flow analysis are presented. Cavitation is addressed as a particular phenomenon, but also its influence on the hydrodynamic parameters. Constant enthalpy vaporization model is used for this purpose and the results will be compared with the photos taken during the cavitation investigation in the tunnel. (Original)

  15. Application perspectives of simulation techniques CFD in nuclear power plants; Perspectivas de aplicacion de tecnicas de modelado CFD en plantas nucleoelectricas

    Energy Technology Data Exchange (ETDEWEB)

    Galindo G, I. F., E-mail: igalindo@iie.org.mx [Instituto de Investigaciones Electricas, Reforma No. 113, Col. Palmira, 62490 Cuernavaca, Morelos (Mexico)

    2013-10-15

    The scenarios simulation in nuclear power plants is usually carried out with system codes that are based on concentrated parameters networks. However situations exist in some components where the flow is predominantly 3-D, as they are the natural circulation, mixed and stratification phenomena. The simulation techniques of computational fluid dynamics (CFD) have the potential to simulate these flows numerically. The use of CFD simulations embraces many branches of the engineering and continues growing, however, in relation to its application with respect to the problems related with the safety in nuclear power plants, has a smaller development, although is accelerating quickly and is expected that in the future they play a more emphasized paper in the analyses. A main obstacle to be able to achieve a general acceptance of the CFD is that the simulations should have very complete validation studies, sometimes not available. In this article a general panorama of the state of the methods application CFD in nuclear power plants is presented and the problem associated to its routine application and acceptance, including the view point of the regulatory authorities. Application examples are revised in those that the CFD offers real benefits and are also presented two illustrative study cases of the application of CFD techniques. The case of a water recipient with a heat source in its interior, similar to spent fuel pool of a nuclear power plant is presented firstly; and later the case of the Boron dilution of a water volume that enters to a nuclear reactor is presented. We can conclude that the CFD technology represents a very important opportunity to improve the phenomena understanding with a strong component 3-D and to contribute in the uncertainty reduction. (Author)

  16. The Role of CFD Simulation in Rocket Propulsion Support Activities

    Science.gov (United States)

    West, Jeff

    2011-01-01

    Outline of the presentation: CFD at NASA/MSFC (1) Flight Projects are the Customer -- No Science Experiments (2) Customer Support (3) Guiding Philosophy and Resource Allocation (4) Where is CFD at NASA/MSFC? Examples of the expanding Role of CFD at NASA/MSFC (1) Liquid Rocket Engine Applications : Evolution from Symmetric and Steady to 3D Unsteady (2)Launch Pad Debris Transport-> Launch Pad Induced Environments (a) STS and Launch Pad Geometry-steady (b) Moving Body Shuttle Launch Simulations (c) IOP and Acoustics Simulations (3)General Purpose CFD Applications (4) Turbomachinery Applications

  17. Advanced CFD and radiotracer techniques - A complementary technology - for industrial multiphase applications

    International Nuclear Information System (INIS)

    Tu, J.Y.

    2004-01-01

    A CFD and RTD Education Package was developed, in which lecture notes, tutorials and computer softwares for both CFD and RTD are included. A user-friendly web-based interface has been prepared to allow lecturers more effectively conducting their training courses or workshops, and to provide students or users more easily learning the CFD and RTD knowledge and practising computer softwares. This report gives an overview of the advances in development and use of CFD models and codes for industrial, particularly multiphase processing applications. Experimental needs for validation and improvement of CFD models and softwares are highlighted. Integration of advanced CFD modelling with radiotracer techniques as a complementary technology for future research and industrial applications is discussed. The features and examples of the developed CFD and RTD Education package are presented. (author)

  18. Reactor physics simulations with coupled Monte Carlo calculation and computational fluid dynamics

    International Nuclear Information System (INIS)

    Seker, V.; Thomas, J.W.; Downar, T.J.

    2007-01-01

    A computational code system based on coupling the Monte Carlo code MCNP5 and the Computational Fluid Dynamics (CFD) code STAR-CD was developed as an audit tool for lower order nuclear reactor calculations. This paper presents the methodology of the developed computer program 'McSTAR'. McSTAR is written in FORTRAN90 programming language and couples MCNP5 and the commercial CFD code STAR-CD. MCNP uses a continuous energy cross section library produced by the NJOY code system from the raw ENDF/B data. A major part of the work was to develop and implement methods to update the cross section library with the temperature distribution calculated by STARCD for every region. Three different methods were investigated and implemented in McSTAR. The user subroutines in STAR-CD are modified to read the power density data and assign them to the appropriate variables in the program and to write an output data file containing the temperature, density and indexing information to perform the mapping between MCNP and STAR-CD cells. Preliminary testing of the code was performed using a 3x3 PWR pin-cell problem. The preliminary results are compared with those obtained from a STAR-CD coupled calculation with the deterministic transport code DeCART. Good agreement in the k eff and the power profile was observed. Increased computational capabilities and improvements in computational methods have accelerated interest in high fidelity modeling of nuclear reactor cores during the last several years. High-fidelity has been achieved by utilizing full core neutron transport solutions for the neutronics calculation and computational fluid dynamics solutions for the thermal-hydraulics calculation. Previous researchers have reported the coupling of 3D deterministic neutron transport method to CFD and their application to practical reactor analysis problems. One of the principal motivations of the work here was to utilize Monte Carlo methods to validate the coupled deterministic neutron transport

  19. EXTENSION OF RTKLIB FOR THE CALCULATION AND VALIDATION OF PROTECTION LEVELS

    Directory of Open Access Journals (Sweden)

    B. Takács

    2017-07-01

    Full Text Available System integrity (i.e. the capability of self-monitoring and the reliability of the positions provided need to be ensured within all safety critical applications of the GPS technology. For the sake of such applications, GPS augmentations, for example Space Based Augmentation Systems (SBAS are to be applied to achieve the required level of integrity. SBAS provides integrity in a multi-step procedure that is laid out in the Radio Technical Commission for Aeronautics (RTCA Minimum Operational Performance Standards (MOPS for airborne navigation equipment using GPS. Besides integrity, SBAS also improves accuracy of positioning via broadcasting corrections to reduce the most important systematic errors on standalone positioning. To quantify integrity, the protection level is defined, which is calculated from the standard deviation of the models broadcast in SBAS. Air Navigation Service Providers, airspace users and aviation authorities need to evaluate the performance of GPS systems and their augmentations. This is a necessary step to define the conditions under which GPS systems can be operationally used and which operations can be supported. For this evaluation two proprietary software are used widely in Europe: Pegasus from Eurocontrol (Butzmühlen et al., 2001 and magicGemini from GMV. Both tools provide several functionalities such as computation of position simulating MOPS-compliant receivers and determination of GNSS augmentation attributes like accuracy, integrity, continuity and availability. RTKLIB is an open source GNSS data processing and analysis tool (Takasu, 2009. The actual version (2.4.3 of RTKLIB has SBAS augmented positioning mode, but no protection level calculation is included. There is an open source project on GitHub3, a fork of RTKLIB 2.4.2 version with an option for WAAS MOPS compliant position calculation, including protection level calculation, too. This was developed by the Houghton Associates, Inc. and tested on Cygwin

  20. International research progress of CFD application in analysis of nuclear power system

    International Nuclear Information System (INIS)

    Li Linsen; Wang Kan; Song Xiaoming

    2009-01-01

    This paper introduces the latest international research progress of CFD application in nuclear reactor system analysis. CFD method has been applied to a few 3-D single phase transient simulations, including flow field modeling of the reactor cores, assemblies, and vessel plenums. On the other hand, CFD method applied to reactor system still needs further validation and benchmarking, meanwhile,the application of CFD also needs to be studied, including the setup of the Best Practice Guidelines (BPG). Furthermore, CFD codes are used to couple with thermal-hydraulic system codes or neutronic codes. Eventually, in two phase field and turbulence modeling, CFD codes are still being developed. (authors)

  1. Synthesis of the OECD/NEA-PSI CFD benchmark exercise

    Energy Technology Data Exchange (ETDEWEB)

    Andreani, Michele, E-mail: Michele.andreani@psi.ch; Badillo, Arnoldo; Kapulla, Ralf

    2016-04-01

    Highlights: • A benchmark exercise on stratification erosion in containment was conducted using a test in the PANDA facility. • Blind calculations were provided by nineteen participants. • Results were compared with experimental data. • A ranking was made. • A large spread of results was observed, with very few simulations providing accurate results for the most important variables, though not for velocities. - Abstract: The third International Benchmark Exercise (IBE-3) conducted under the auspices of OECD/NEA is based on the comparison of blind CFD simulations with experimental data addressing the erosion of a stratified layer by an off-axis buoyant jet in a large vessel. The numerical benchmark exercise is based on a dedicated experiment in the PANDA facility conducted at the Paul Scherrer Institut (PSI) in Switzerland, using only one vessel. The use of non-prototypical fluids (i.e. helium as simulant for hydrogen, and air as simulant for steam), and the consequent absence of the complex physical effects produced by steam condensation enhanced the suitability of the data for CFD validation purposes. The test started with a helium–air layer at the top of the vessel and air in the lower part. The helium-rich layer was gradually eroded by a low-momentum air/helium jet emerging at a lower elevation. Blind calculation results were submitted by nineteen participants, and the calculation results have been compared with the PANDA data. This report, adopting the format of the reports for the two previous exercises, includes a ranking of the contributions, where the largest weight is given to the time progression of the erosion of the helium-rich layer. In accordance with the limited scope of the benchmark exercise, this report is more a collection of comparisons between calculated results and data than a synthesis. Therefore, the few conclusions are based on the mere observation of the agreement of the various submissions with the test result, and do not

  2. Comparison of CFD and Test Techniques for Cavitation Inception

    International Nuclear Information System (INIS)

    Lee, Do Hwan; Park, Sung Keun; Lee, Sun Ki; Kim, Byung Kon

    2009-01-01

    Cavitation erosion on centrifugal pump impellers is a one of the fundamental factors that cause performance degradation and life shortening of the pumps. One approach to estimate the expected life of an impeller is to use sheet cavity length on the blade surface. While observing the cavity length is more suitable to accurately predict the impeller damage, it is not readily available in the field or on the test stand. Recently, the prediction of the cavity length by using commercial CFD codes has been tried by several authors. As an alternative to direct measure the cavity length of an impeller, a means of estimating cavity length of an impeller based on the relation of operating NPSH to that of 3% NPSH and inception NPSH was developed by Cooper. Although this method seems to be attractive, it is not easy to accurately estimate the inception NPSH without flow visualization. Some recent researchers has been paid attention to apply the high frequency Acoustic Emission(AE) technique to detect cavitation inception of pumps. As an effort to better estimate the cavity length without relying on flow visualization, CFD calculations and experiments were performed and then the results are compared in this study

  3. Verification, validation and application of NEPTUNE-CFD to two-phase Pressurized Thermal Shocks

    Energy Technology Data Exchange (ETDEWEB)

    Mérigoux, N., E-mail: nicolas.merigoux@edf.fr [Electricité de France, R& D Division, 6 Quai Watier, 78401 Chatou (France); Laviéville, J.; Mimouni, S.; Guingo, M.; Baudry, C. [Electricité de France, R& D Division, 6 Quai Watier, 78401 Chatou (France); Bellet, S., E-mail: serge.bellet@edf.fr [Electricité de France, Thermal & Nuclear Studies and Projects Division, 12-14 Avenue Dutriévoz, 69628 Villeurbanne (France)

    2017-02-15

    Nuclear Power Plants are subjected to a variety of ageing mechanisms and, at the same time, exposed to potential Pressurized Thermal Shock (PTS) – characterized by a rapid cooling of the Reactor Pressure Vessel (RPV) wall. In this context, NEPTUNE-CFD is developed and used to model two-phase PTS in an industrial configuration, providing temperature and pressure fields required to assess the integrity of the RPV. Furthermore, when using CFD for nuclear safety demonstration purposes, EDF applies a methodology based on physical analysis, verification, validation and application to industrial scale (V&V), to demonstrate the quality of, and the confidence in results obtained. By following this methodology, each step must be proved to be consistent with the others, and with the final goal of the calculations. To this effect, a chart demonstrating how far the validation step of NEPTUNE-CFD is covering the PTS application will be drawn. A selection of the code verification and validation cases against different experiments will be described. For results consistency, a single and mature set of models – resulting from the knowledge acquired during the code development over the last decade – has been used. From these development and validation feedbacks, a methodology has been set up to perform industrial computations. Finally, the guidelines of this methodology based on NEPTUNE-CFD and SYRTHES coupling – to take into account the conjugate heat transfer between liquid and solid – will be presented. A short overview of the engineering approach will be given – starting from the meshing process, up to the results post-treatment and analysis.

  4. Validating CFD Predictions of Pharmaceutical Aerosol Deposition with In Vivo Data.

    Science.gov (United States)

    Tian, Geng; Hindle, Michael; Lee, Sau; Longest, P Worth

    2015-10-01

    CFD provides a powerful approach to evaluate the deposition of pharmaceutical aerosols; however, previous studies have not compared CFD results of deposition throughout the lungs with in vivo data. The in vivo datasets selected for comparison with CFD predictions included fast and slow clearance of monodisperse aerosols as well as 2D gamma scintigraphy measurements for a dry powder inhaler (DPI) and softmist inhaler (SMI). The CFD model included the inhaler, a characteristic model of the mouth-throat (MT) and upper tracheobronchial (TB) airways, stochastic individual pathways (SIPs) representing the remaining TB region, and recent CFD-based correlations to predict pharmaceutical aerosol deposition in the alveolar airways. For the monodisperse aerosol, CFD predictions of total lung deposition agreed with in vivo data providing a percent relative error of 6% averaged across aerosol sizes of 1-7 μm. With the DPI and SMI, deposition was evaluated in the MT, central airways (bifurcations B1-B7), and intermediate plus peripheral airways (B8 through alveoli). Across these regions, CFD predictions produced an average relative error <10% for each inhaler. CFD simulations with the SIP modeling approach were shown to accurately predict regional deposition throughout the lungs for multiple aerosol types and different in vivo assessment methods.

  5. CFD validation by measurement of specialized ventilation equipments on duct tract

    Directory of Open Access Journals (Sweden)

    Sehnalek Stanislav

    2017-01-01

    Full Text Available This article describes measurement of HVAC distribution box on air duct track in Laboratory of Environmental Engineering (LEE. Firstly, the paper describes the LEE and then measurement apparatus with description of calculation methods. Then follows specification of sample with introduction to newly developed equipment for positioning of the anemometer. The evaluation of results of measurements with CFD comparison follows. The article is concluded with discussion over measured data with an outline for further research.

  6. Preliminary CFD Analysis for HVAC System Design of a Containment Building

    Energy Technology Data Exchange (ETDEWEB)

    Son, Sung Man; Choi, Choengryul [ELSOLTEC, Yongin (Korea, Republic of); Choo, Jae Ho; Hong, Moonpyo; Kim, Hyungseok [KEPCO Engineering and Construction, Gimcheon (Korea, Republic of)

    2016-10-15

    HVAC (Heating, Ventilation, Air Conditioning) system has been mainly designed based on overall heat balance and averaging concepts, which is simple and useful for designing overall system. However, such a method has the disadvantage that cannot predict the local flow and temperature distributions in a containment building. In this study, a CFD (Computational Fluid Dynamics) preliminary analysis is carried out to obtain detailed flow and temperature distributions in a containment building and to ensure that such information can be obtained via CFD analysis. This approach can be useful for hydrogen analysis in an accident related to hydrogen released into a containment building. In this study, CFD preliminary analysis has been performed to obtain the detailed information of the reactor containment building by using the CFD analysis techniques and to ensure that such information can be obtained via CFD analysis. We confirmed that CFD analysis can offer enough detailed information about flow patterns and temperature field and that CFD technique is a useful tool for HVAC design of nuclear power plants.

  7. Best Practice Guidelines for the use of CFD in Nuclear Reactor Safety Applications

    International Nuclear Information System (INIS)

    Mahaffy, J.; Chung, B.; Song, C.; Dubois, F.; Graffard, E.; Ducros, F.; Heitsch, M.; Scheuerer, M.; Henriksson, M.; Komen, E.; Moretti, F.; Morii, T.; Muehlbauer, P.; Rohde, U.; Smith, B. L.; Watanabe, T.; Zigh, G.

    2007-01-01

    In May 2002, an 'Exploratory Meeting of Experts to Define an Action Plan on the Application of Computational Fluid Dynamics (CFD) Codes to Nuclear Reactor Safety Problems' was held at Aix-en-Provence, France. One of three recommended actions was the formation of this writing group to report on the need for guidelines for use of CFD in single phase Nuclear Reactor Safety (NRS) applications. CSNI approved this writing group at the end of 2002, and work began in March 2003. A final report was submitted to GAMA in September 2004, summarizing existing Best Practice Guidelines (BPG) for CFD, and recommending creation of a BPG document for Nuclear Reactor Safety (NRS) applications. The present document is intended to provide an internally complete set of guidelines for a range of single phase applications of CFD to NRS problems. However, it is not meant to be comprehensive; it is recognized that for any specific application a higher level of specificity is possible on questions of nodalization, model selection, and validation. This document should provide direct guidance on the key considerations in known single phase applications, and general directions for resolving remaining details. The intent is that it will serve as a template for further application specific (e.g. PTS, induced break) BPG documents that will provide much more detailed information and examples. The document begins with a summary of NRS related CFD analysis in countries represented by the authors. Chapter 3 deals with definition of the problem and its solution approach. This includes isolation of the portion of the NRS problem most in need of CFD, and use of a classic thermal hydraulic (TH) safety code to provide boundary conditions for the CFD based upon less detailed simulation of the balance of plant. Chapter 4 provides guidance in choosing between various options, and also discusses use of a transient calculation with tightly coupled CFD and TH codes. Chapter 5 discusses selection of physical

  8. Effectiveness of two-dimensional CFD simulations for Darrieus VAWTs: a combined numerical and experimental assessment

    International Nuclear Information System (INIS)

    Bianchini, Alessandro; Balduzzi, Francesco; Bachant, Peter; Ferrara, Giovanni; Ferrari, Lorenzo

    2017-01-01

    Highlights: • 2D CFD simulations compared to experimental tow-tank data on the RVAT test model. • The use of CFD with open-field-like boundaries is suggested. • A reliable estimation of the turbine performance and the wake structure is obtained. • The transitional turbulence model is recommended for low TSRs and/or small rotors. • The wake analysis identified the main vortical structures generated by the blades. - Abstract: Thanks to the continuous improvement of calculation resources, computational fluid dynamics (CFD) is expected to provide in the next few years a cost-effective and accurate tool to improve the understanding of the unsteady aerodynamics of Darrieus wind turbines. This rotor type is in fact increasingly welcome by the wind energy community, especially in case of small size applications and/or non-conventional installation sites. In the present study, unique tow tank experimental data on the performance curve and the near-wake structure of a Darrieus rotor were used as a benchmark to validate the effectiveness of different CFD approaches. In particular, a dedicated analysis is provided to assess the suitability, the effectiveness and the future prospects of simplified two-dimensional (2D) simulations. The correct definition of the computational domain, the selection of the turbulence models and the correction of simulated data for the parasitic torque components are discussed in this study. Results clearly show that, (only) if properly set, two-dimensional CFD simulations are able to provide - with a reasonable computational cost - an accurate estimation of the turbine performance and also quite reliably describe the attended flow-field around the rotor and its wake.

  9. Computational Fluid Dynamics (CFD) in Nuclear Reactor Safety (NRS) - Proceedings of the workshop on Experiments and CFD Code Application to Nuclear Reactor Safety (XCFD4NRS)

    International Nuclear Information System (INIS)

    2008-01-01

    Computational Fluid Dynamics (CFD) is to an increasing extent being adopted in nuclear reactor safety analyses as a tool that enables specific safety relevant phenomena occurring in the reactor coolant system to be better described. The Committee on the Safety of Nuclear Installations (CSNI), which is responsible for the activities of the OECD Nuclear Energy Agency that support advancing the technical base of the safety of nuclear installations, has in recent years conducted an important activity in the CFD area. This activity has been carried out within the scope of the CSNI working group on the analysis and management of accidents (GAMA), and has mainly focused on the formulation of user guidelines and on the assessment and verification of CFD codes. It is in this GAMA framework that a first workshop CFD4NRS was organized and held in Garching, Germany in 2006. Following the CFD4NRS workshop, this XCFD4NRS Workshop was intended to extend the forum created for numerical analysts and experimentalists to exchange information in the field of Nuclear Reactor Safety (NRS) related activities relevant to Computational Fluid Dynamics (CFD) validation, but this time with more emphasis placed on new experimental techniques and two-phase CFD applications. The purpose of the workshop was to provide a forum for numerical analysts and experimentalists to exchange information in the field of NRS-related activities relevant to CFD validation, with the objective of providing input to GAMA CFD experts to create a practical, state-of-the-art, web-based assessment matrix on the use of CFD for NRS applications. The scope of XCFD4NRS includes: - Single-phase and two-phase CFD simulations with an emphasis on validation in areas such as: boiling flows, free-surface flows, direct contact condensation and turbulent mixing. These applications should relate to NRS-relevant issues such as: pressurized thermal shocks, critical heat flux, pool heat exchangers, boron dilution, hydrogen

  10. Assessment of computational fluid dynamics (CFD) for nuclear reactor safety problems

    International Nuclear Information System (INIS)

    Smith, B. L.; Andreani, M.; Bieder, U.; Bestion, D.; Ducros, F.; Graffard, E.; Heitsch, M.; Scheuerer, M.; Henriksson, M.; Hoehne, T.; Rohde, U.; Lucas, D.; Komen, E.; Houkema, M.; Mahaffy, J.; Moretti, F.; Morii, T.; Muehlbauer, P.; Song, C.H.; Zigh, G.; Menter, F.; Watanabe, T.

    2008-01-01

    The basic objective of the present work was to provide documented evidence of the need to perform CFD simulations in Nuclear Reactor Safety (NRS), concentrating on single-phase applications, and to assess the competence of the present generation of CFD codes to perform these simulations reliably. The fulfilling of this objective involves multiple tasks, summarized as: to provide a classification of NRS problems requiring CFD analysis, to identify and catalogue existing CFD assessment bases, to identify shortcomings in CFD approaches, to put into place a means for extending the CFD assessment database, with an emphasis on NRS applications. The resulting document is presented here. After some introductory remarks, chapter 3 lists twenty-two NRS issues for which it is considered that the application of CFD would bring real benefits in terms of better predictive capability. This classification is followed by a short description of the safety issue, a state-of-the-art summary of what has been attempted, and what is still needed to be done to improve reliability. Chapter 4 details the assessment bases that have already been established in both the nuclear and non-nuclear domains, and discusses the usefulness and relevance of the work to NRS applications, where appropriate. This information is augmented in Chapter 5 by descriptions of the existing CFD assessment bases that have been established around specific, NRS problems. Typical examples are experiments devoted to the boron dilution issue, pressurised thermal shock, and thermal fatigue in pipes. Chapter 6 is devoted to identifying the technology gaps which need to be closed to make CFD a more trustworthy analytical tool. Some deficiencies identified are lack of a Phenomenon Identification and Ranking Table (PIRT), limitations in the range of application of turbulence models, coupling of CFD with neutronics and system codes, and computer power limitations. Most CFD codes currently being used have their own, custom

  11. CFD analysis on heat transfer in low Prandtl number fluid flows

    Energy Technology Data Exchange (ETDEWEB)

    Borgohain, A.; Maheshwari, N.K.; Vijayan, P.K.; Sinha, R.K., E-mail: bananta@barc.gov.in [Bhabha Atomic Research Centre, Reactor Engineering Div., Trombay, Mumbai (India)

    2011-07-01

    Use of Computational Fluid Dynamics (CFD) code is helpful for designing liquid metal cooled nuclear reactor systems. Before using any CFD code proper evaluation of the code is essential for simulation of heat transfer in liquid metal flow. In this paper, a review of the literature on the correlations for liquid metal heat transfer is carried out and a comparison with experimental results is performed. CFD analysis is carried out using PHOENICS-3.6 code on heat transfer in molten Lead Bismuth Eutectic (LBE) flowing through tube. Turbulent flow analyses are carried out for the evaluation of the CFD code. The CFD results are compared with the available correlations. Assessment of various turbulence models and correlations for turbulent Prandtl number in the tube geometry are carried out. From the analysis it is found that, the CFD prediction can be improved with modified turbulent Prandtl number in the turbulence models. (author)

  12. An Integrated Lumped Parameter-CFD approach for off-design ejector performance evaluation

    International Nuclear Information System (INIS)

    Besagni, Giorgio; Mereu, Riccardo; Chiesa, Paolo; Inzoli, Fabio

    2015-01-01

    Highlights: • We validate a CFD approach for a convergent nozzle ejector using global and local measurement. • We evaluate seven RANS turbulence models for convergent nozzle ejector. • We introduce a lumped parameter model for on-design and off-design ejector performance evaluation. • We analyze the relationship between local flow behavior and lumped parameters of the model. • We discuss how to improve predicting capabilities of the model by variable parameters calibrated on CFD simulations. - Abstract: This paper presents an Integrated Lumped Parameter Model-Computational Fluid-Dynamics approach for off-design ejector performance evaluation. The purpose of this approach is to evaluate the entrainment ratio, for a fixed geometry, in both on-design and off-design operating conditions. The proposed model is based on a Lumped Parameter Model (LPM) with variable ejector component efficiencies provided by CFD simulations. The CFD results are used for developing maps for ejector component efficiencies in a broad range of operating conditions. The ejector component efficiency maps couple the CFD and the LPM techniques for building an Integrated LPM-CFD approach. The proposed approach is demonstrated for a convergent nozzle ejector and the paper is structured in four parts. At first, the CFD approach is validated by global and local data and seven Reynolds Averaged Navier Stokes (RANS) turbulence models are compared: the k–ω SST showed good performance and was selected for the rest of the analysis. At second, a Lumped Parameter Model (LPM) for subsonic ejector is developed and the ejector component efficiencies have been defined. At third, the CFD approach is used to investigate the flow field, to analyze its influence on ejector component efficiencies and to propose efficiency correlations and maps linking ejector component efficiencies and local flow quantities. In the last part, the efficiency maps are embedded into the lumped parameter model, thus creating

  13. Experimental investigation and CFD validation of Horizontal Air/Water slug flow

    International Nuclear Information System (INIS)

    Vallee, Christophe; Hoehne, Thomas

    2007-01-01

    For the investigation of co-current two-phase flows at atmospheric pressure and room temperature, the Horizontal Air/Water Channel (HAWAC) was built at Forschungszentrum Dresden-Rossendorf (FZD). At the channel inlet, a special device provides adjustable and well-defined inlet boundary conditions and therefore very good CFD validation possibilities. The HAWAC facility is designed for the application of optical measurement techniques, which deliver the high resolution required for CDF validation. Therefore, the 8 m long acrylic glass test-section with rectangular cross-section provides good observation possibilities. High-speed video observation was applied during slug flow. The camera images show the generation of slug flow from the inlet of the test-section. Parallel to the experiments, CFD calculations were carried out. The aim of the numerical simulations is to validate the prediction of slug flow with the existing multiphase flow models built in the commercial code ANSYS CFX. The Euler-Euler two-fluid model with the free surface option was applied to a grid of 600,000 control volumes. The turbulence was modelled separately for each phase using the k-ω based shear stress transport (SST) turbulence model. The results compare well in terms of slug formation, and breaking. The qualitative agreement between calculation and experiment is encouraging, while quantitative comparison show that further model improvement is needed. (author)

  14. CFD Validation of Gas Injection in Flowing Mercury over Vertical Smooth and Grooved Wall

    International Nuclear Information System (INIS)

    Abdou, Ashraf A.; Wendel, Mark W.; Felde, David K.; Riemer, Bernie

    2009-01-01

    The Spallation Neutron Source (SNS) is an accelerator-based neutron source at Oak Ridge National Laboratory (ORNL). The nuclear spallation reaction occurs when a proton beam hits liquid mercury. This interaction causes thermal expansion of the liquid mercury which produces high pressure waves. When these pressure waves hit the target vessel wall, cavitation can occur and erode the wall. Research and development efforts at SNS include creation of a vertical protective gas layer between the flowing liquid mercury and target vessel wall to mitigate the cavitation damage erosion and extend the life time of the target. Since mercury is opaque, computational fluid dynamics (CFD) can be used as a diagnostic tool to see inside the liquid mercury and guide the experimental efforts. In this study, CFD simulations of three dimensional, unsteady, turbulent, two-phase flow of helium gas injection in flowing liquid mercury over smooth, vertically grooved and horizontally grooved walls are carried out with the commercially available CFD code Fluent-12 from ANSYS. The Volume of Fluid (VOF) model is used to track the helium-mercury interface. V-shaped vertical and horizontal grooves with 0.5 mm pitch and about 0.7 mm depth were machined in the transparent wall of acrylic test sections. Flow visualization data of helium gas coverage through transparent test sections is obtained with a high-speed camera at the ORNL target test facility (TTF). The helium gas mass flow rate is 8 mg/min and introduced through a 0.5 mm diameter port. The local mercury velocity is 0.9 m/s. In this paper, the helium gas flow rate and the local mercury velocity are kept constant for the three cases. Time integration of predicted helium gas volume fraction over time is done to evaluate the gas coverage and calculate the average thickness of the helium gas layer. The predicted time-integrated gas coverage over vertically grooved and horizontally grooved test sections is better than over a smooth wall. The

  15. Detailed disc assembly temperature prediction: comparison between CFD and simplified engineering methods

    CSIR Research Space (South Africa)

    Snedden, Glen C

    2003-09-01

    Full Text Available Institute of Aeronautics and Astronautics Inc. All rights reserved. DETAILED DISC ASSEMBLY TEMPERATURE PREDICTION: COMPARISON BETWEEN CFD AND SIMPLIFIED ENGINEERING METHODS ISABE-2005-1130 Glen Snedden, Thomas Roos and Kavendra Naidoo CSIR, Defencetek... transfer and conduction code (Gaugler, 1978) Taw Adiabatic Wall Temperature y+ Near wall Reynolds number Introduction In order to calculate life degradation of gas turbine disc assemblies, it is necessary to model the transient thermal and mechanical...

  16. CFD-supported development of small-scale biomass furnaces; CFD-gestuetzte Entwicklung von Biomassefeuerungen im kleinen Leistungsbereich

    Energy Technology Data Exchange (ETDEWEB)

    Scharler, R. [Bios Bioenergiesystem GmbH, Graz (Austria); Obernberger, I. [Technische Univ. Eindhoven (Netherlands). Thermochemische Biomassekonversion; Weissinger, A. [Oesterreichische Kraft und Waerme aus Biomasse GmbH (KWB), St. Margarethen/Raab (Austria). Bereich Forschung und Entwicklung; Schmidt, W. [Oesterreichische Kraft und Waerme aus Biomasse GmbH (KWB), St. Margarethen/Raab (Austria). Bereich Produktentwicklung, Umwelt- und Informationsmanagement

    2005-07-01

    Despite the complexity of solid biomass combustion, the Bios Bioenergiesysteme GmbH, Graz, Austria, has successfully developed and optimised several biomass furnaces in the range of 500 kW to 30 MW based on CFD (Computational Fluid Dynamics). A project carried out in co-operation with the KWB Kraft und Waerme aus Biomasse GmbH, St. Margarethen, Austria, demonstrates the application of CFD for the efficient and improved design of small-scale furnaces for solid biofuels like pellets and wood chips as basis for a series production. (orig.)

  17. Best Practices for Reduction of Uncertainty in CFD Results

    Science.gov (United States)

    Mendenhall, Michael R.; Childs, Robert E.; Morrison, Joseph H.

    2003-01-01

    This paper describes a proposed best-practices system that will present expert knowledge in the use of CFD. The best-practices system will include specific guidelines to assist the user in problem definition, input preparation, grid generation, code selection, parameter specification, and results interpretation. The goal of the system is to assist all CFD users in obtaining high quality CFD solutions with reduced uncertainty and at lower cost for a wide range of flow problems. The best-practices system will be implemented as a software product which includes an expert system made up of knowledge databases of expert information with specific guidelines for individual codes and algorithms. The process of acquiring expert knowledge is discussed, and help from the CFD community is solicited. Benefits and challenges associated with this project are examined.

  18. Dynamic analysis of the pump system based on MOC–CFD coupled method

    International Nuclear Information System (INIS)

    Yang, Shuai; Chen, Xin; Wu, Dazhuan; Yan, Peng

    2015-01-01

    Highlights: • MOC–CFD coupled method was proposed to get the pump internal and external characteristics. • The coupled strategy and procedure were explained. • Some typical simulation cases were made for different factors. • The pump head deviation grows with the severity of the transient. • Valve closure law in linear and longer pipeline will cause higher pump head deviation. - Abstract: The dynamic characteristics of pump response to transient events were investigated by combining the Method of Characteristic (MOC) and Computational Fluid Dynamics (CFD) together. In a typical pump–pipeline–valve system, similar to the reactor system, the pump is treated as three-dimensional CFD model using Fluent code, whereas the rest is represented by one-dimensional components using MOC. A description of the coupling theory and procedure ensuring proper communication within the two codes is given. Several transient flow operations have been carried out. In the initial steady-state simulation, the coupled method could accurately find the operating condition of the pump when the valve is fully open. When the valve is closed rapidly, preliminary comparative calculations demonstrate that the coupled method is efficient in simulating the dynamic behavior of the pump and capable of getting detailed fluid field evolutions inside the pump. Deviation between the dynamic pump head and the value given by the steady-state curve at the same instantaneous flow-rate was established, and the cause of the deviation was further explained by the comparison of pump internal and external characteristics. Furthermore, it was found that the deviation grows with the severity of the transient. In addition, the effects of valve closure laws and pipe length on the pump dynamic performances were evaluated. All the results showed that MOC–CFD is an efficient and promising way for simulating the interaction between pump model and piping system

  19. Development of a GUI Based Front End for Open Source CFD Program, OpenFOAM

    Energy Technology Data Exchange (ETDEWEB)

    Han, Samhee; Lee, Youngjin; Kim, Hyongchol; Park, Sunbyung; Kim, Hyunjik [Nuclear Safety Evaluation, Daejeon (Korea, Republic of)

    2013-05-15

    OpenFOAM is sorely lacking in user friendliness as it runs in console mode under Li nux. Run{sub F}OAM was developed to greatly simplify the task of running an OpenFOAM calculation under Windows OS. Run{sub F}OAM was written using Delphi object pascal language, and GLScene package was used for the 3D graphics. Verification of Run{sub F}OAM was carried out by performing some OpenFOAM CFD calculations provided in OpenFOAM package, and these showed that the use of Run{sub F}OAM is simple whilst providing sufficient allowances in user modifications. Run{sub F}oam, a GUI based front end program to simplify running Open Foam CFD cases, has been developed. By incorporating numerous GUI in the program, Run{sub F}oam has demonstrated that running an Open Foam case can be easily accomplished. There is a potential for further development as the Open Foam has the great advantage of being free to develop and to use. There is also a potential to couple or interface the Open Foam with the systems analysis code such as Relap5.

  20. An implementation of an aeroacoustic prediction model for broadband noise from a vertical axis wind turbine using a CFD informed methodology

    Science.gov (United States)

    Botha, J. D. M.; Shahroki, A.; Rice, H.

    2017-12-01

    This paper presents an enhanced method for predicting aerodynamically generated broadband noise produced by a Vertical Axis Wind Turbine (VAWT). The method improves on existing work for VAWT noise prediction and incorporates recently developed airfoil noise prediction models. Inflow-turbulence and airfoil self-noise mechanisms are both considered. Airfoil noise predictions are dependent on aerodynamic input data and time dependent Computational Fluid Dynamics (CFD) calculations are carried out to solve for the aerodynamic solution. Analytical flow methods are also benchmarked against the CFD informed noise prediction results to quantify errors in the former approach. Comparisons to experimental noise measurements for an existing turbine are encouraging. A parameter study is performed and shows the sensitivity of overall noise levels to changes in inflow velocity and inflow turbulence. Noise sources are characterised and the location and mechanism of the primary sources is determined, inflow-turbulence noise is seen to be the dominant source. The use of CFD calculations is seen to improve the accuracy of noise predictions when compared to the analytic flow solution as well as showing that, for inflow-turbulence noise sources, blade generated turbulence dominates the atmospheric inflow turbulence.

  1. Development and validation of three-dimensional CFD techniques for reactor safety applications. Final report

    International Nuclear Information System (INIS)

    Buchholz, Sebastian; Palazzo, Simone; Papukchiev, Angel; Scheurer Martina

    2016-12-01

    The overall goal of the project RS 1506 ''Development and Validation of Three Dimensional CFD Methods for Reactor Safety Applications'' is the validation of Computational Fluid Dynamics (CFD) software for the simulation of three -dimensional thermo-hydraulic heat and fluid flow phenomena in nuclear reactors. For this purpose a wide spectrum of validation and test cases was selected covering fluid flow and heat transfer phenomena in the downcomer and in the core of pressurized water reactors. In addition, the coupling of the system code ATHLET with the CFD code ANSYS CFX was further developed and validated. The first choice were UPTF experiments where turbulent single- and two-phase flows were investigated in a 1:1 scaled model of a German KONVOI reactor. The scope of the CFD calculations covers thermal mixing and stratification including condensation in single- and two-phase flows. In the complex core region, the flow in a fuel assembly with spacer grid was simulated as defined in the OECD/NEA Benchmark MATIS-H. Good agreement are achieved when the geometrical and physical boundary conditions were reproduced as realistic as possible. This includes, in particular, the consideration of heat transfer to walls. The influence of wall modelling on CFD results was investigated on the TALL-3D T01 experiment. In this case, the dynamic three dimensional fluid flow and heat transfer phenomena were simulated in a Generation IV liquid metal cooled reactor. Concurrently to the validation work, the coupling of the system code ATHLET with the ANSYS CFX software was optimized and expanded for two-phase flows. Different coupling approaches were investigated, in order to overcome the large difference between CPU-time requirements of system and CFD codes. Finally, the coupled simulation system was validated by applying it to the simulation of the PSI double T-junction experiment, the LBE-flow in the MYRRA Spallation experiment and a demonstration test case simulating a pump trip

  2. Experiments and CFD simulations of DTBP pool fires; Experimentelle Untersuchungen und CFD-Simulationen von DTBP-Poolfeuern

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Hyunjoo

    2007-07-01

    Flammable liquids are used increasingly often world-wide. Their storage, transport and chemical reactions are a considerable safety problem in industrial plants. Heat release and combustion products of big fires are a high hazard for persons, the immediate vicinity and the environment in general. Investigations of pool fires were carried out for a realistic assessment of the potential hazards to persons and plants in the immediate vicinity. Most of the available data on fire effects, safety distances and other measures relevant to fire protection are for hydrocarbons, alcohols and liquefied gases. LIttle is known on pool fires of liquid organic peroxides, which have quite different combustion characteristics with higher mass burnup rates and higher heat emissions into the vicinity. The dissertation presents experiments to characterize the combustion characteristics of organic peroxides as a function of the pool diameter. Di-tert-butylperoxide (DTBPL) was chosen for the experiments because it has a relatively high thermal stability as compared to other organic peroxides. Mass burnup rates, flame temperatures, the surface emissive power (SEP), the strength of thermal radiation and the flame length were measured as a function of the pool diameter. Further, parameters required for CFD simulations of DTBP pool fires were identified experimentally in order to ensure realistic modelling of real fires as a basis, e.g., for assessing safety distances. Experiments on large pool fires are costly and require much equipment and technical preparations so that fires are limited to pool diameters of only a few meters as a rule. CFD simulations would be capable of improving the prediction of safety-relevant parameters like flame temperature, surface emissive power, radiation strength and flame length without limiting the pool diameter or the fuel volume. Appropriate sub-models were used for modelling pool fires of organic peroxides, and the simulation results were critically

  3. CFD simulations of the MEXICO rotor

    DEFF Research Database (Denmark)

    Bechmann, Andreas; Sørensen, Niels N.; Zahle, Frederik

    2011-01-01

    The wake behind a wind turbine model is investigated using Computational Fluid Dynamics (CFD), and results are compared with measurements. The turbine investigated is the three‐bladed test rotor (D = 4.5 m) used in the Model Experiments in Controlled Conditions (MEXICO) wind tunnel experiment....... During the MEXICO experiment, particle image velocimetry measurements of the induction upstream and downstream of the rotor were performed for different operating conditions, giving a unique dataset to verify theoretical models and CFD models. The present paper first describes the efforts in reproducing...

  4. Mass transfer and slag-metal reaction in ladle refining : a CFD approach

    OpenAIRE

    Ramström, Eva

    2009-01-01

      In order to optimise the ladle treatment mass transfer modelling of aluminium addition and homogenisation time was carried out. It was stressed that incorporating slag-metal reactions into the mass transfer modelling strongly would enhance the reliability and amount of information to be analyzed from the CFD calculations.   In the present work, a thermodynamic model taking all the involved slag metal reactions into consideration was incorporated into a 2-D fluid flow model of an argon stirr...

  5. Evaluation of DNBR calculation methods for advanced digital core protection system

    International Nuclear Information System (INIS)

    Ihn, W. K.; Hwang, D. H.; Pak, Y. H.; Yoon, T. Y.

    2003-01-01

    This study evaluated the on-line DNBR calculation methods for an advanced digital core protection system in PWR, i.e., subchannel analysis and group-channel analysis. The subchannel code MATRA and the four-channel codes CETOP-D and CETOP2 were used here. CETOP2 is most simplified DNBR analysis code which is implemented in core protection calculator in Korea standard nuclear power plants. The detailed subchannel code TORC was used as a reference calculation of DNBR. The DNBR uncertainty and margin were compared using allowable operating conditions at Yonggwang nuclear units 3-4. The MATRA code using a nine lumping-channel model resulted in smaller mean and larger standard deviation of the DNBR error distribution. CETOP-D and CETOP2 showed conservatively biased mean and relatively smaller standard deviation of the DNBR error distribution. MATRA and CETOP-D w.r.t CETOP2 showed significant increase of the DNBR available margin at normal operating condition. Taking account for the DNBR uncertainty, MATRA and CETOP-D over CETOP2 were estimated to increase the DNBR net margin by 2.5%-9.8% and 2.5%-3.3%, respectively

  6. Computational Fluid Dynamics (CFD) Technology Programme 1995- 1999

    Energy Technology Data Exchange (ETDEWEB)

    Haekkinen, R.J.; Hirsch, C.; Krause, E.; Kytoemaa, H.K. [eds.

    1997-12-31

    The report is a mid-term evaluation of the Computational Fluid Dynamics (CFD) Technology Programme started by Technology Development Centre Finland (TEKES) in 1995 as a five-year initiative to be concluded in 1999. The main goal of the programme is to increase the know-how and application of CFD in Finnish industry, to coordinate and thus provide a better basis for co-operation between national CFD activities and encouraging research laboratories and industry to establish co-operation with the international CFD community. The projects of the programme focus on the following areas: (1) studies of modeling the physics and dynamics of the behaviour of fluid material, (2) expressing the physical models in a numerical mode and developing a computer codes, (3) evaluating and testing current physical models and developing new ones, (4) developing new numerical algorithms, solvers, and pre- and post-processing software, and (5) applying the new computational tools to problems relevant to their ultimate industrial use. The report consists of two sections. The first considers issues concerning the whole programme and the second reviews each project

  7. Extending the capabilities of CFD codes to assess ash related problems

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen; Rosendahl, Lasse Aistrup; Baxter, B. B.

    2004-01-01

    This paper discusses the application of FLUENT? in theanalysis of grate-fired biomass boilers. A short description of theconcept used to model fuel conversion on the grate and the couplingto the CFD code is offered. The development and implementation ofa CFD-based deposition model is presented...... in the reminder of thepaper. The growth of deposits on furnace walls and super heatertubes is treated including the impact on heat transfer rates determinedby the CFD code. Based on the commercial CFD code FLUENT?,the overall model is fully implemented through the User DefinedFunctions. The model is configured...

  8. A CFD study of Screw Compressor Motor Cooling Analysis

    Science.gov (United States)

    Branch, S.

    2017-08-01

    Screw compressors use electric motors to drive the male screw rotor. They are cooled by the suction refrigerant vapor that flows around the motor. The thermal conditions of the motor can dramatically influence the performance and reliability of the compressor. The more optimized this flow path is, the better the motor performance. For that reason it is important to understand the flow characteristics around the motor and the motor temperatures. Computational fluid dynamics (CFD) can be used to provide a detailed analysis of the refrigerant’s flow behavior and motor temperatures to identify the undesirable hot spots in the motor. CFD analysis can be used further to optimize the flow path and determine the reduction of hot spots and cooling effect. This study compares the CFD solutions of a motor cooling model to a motor installed with thermocouples measured in the lab. The compressor considered for this study is an R134a screw compressor. The CFD simulation of the motor consists of a detailed breakdown of the stator and rotor components. Orthotropic thermal conductivity material properties are used to represent the simplified motor geometry. In addition, the analysis includes the motor casings of the compressor to draw heat away from the motor by conduction. The study will look at different operating conditions and motor speeds. Finally, the CFD study will investigate the predicted motor temperature change by varying the vapor mass flow rates and motor speed. Recommendations for CFD modeling of such intricate heat transfer phenomenon have thus been proposed.

  9. Simplified Analytic Approach of Pole-to-Pole Faults in MMC-HVDC for AC System Backup Protection Setting Calculation

    Directory of Open Access Journals (Sweden)

    Tongkun Lan

    2018-01-01

    Full Text Available AC (alternating current system backup protection setting calculation is an important basis for ensuring the safe operation of power grids. With the increasing integration of modular multilevel converter based high voltage direct current (MMC-HVDC into power grids, it has been a big challenge for the AC system backup protection setting calculation, as the MMC-HVDC lacks the fault self-clearance capability under pole-to-pole faults. This paper focused on the pole-to-pole faults analysis for the AC system backup protection setting calculation. The principles of pole-to-pole faults analysis were discussed first according to the standard of the AC system protection setting calculation. Then, the influence of fault resistance on the fault process was investigated. A simplified analytic approach of pole-to-pole faults in MMC-HVDC for the AC system backup protection setting calculation was proposed. In the proposed approach, the derived expressions of fundamental frequency current are applicable under arbitrary fault resistance. The accuracy of the proposed approach was demonstrated by PSCAD/EMTDC (Power Systems Computer-Aided Design/Electromagnetic Transients including DC simulations.

  10. A CFD validation roadmap for hypersonic flows

    Science.gov (United States)

    Marvin, Joseph G.

    1993-01-01

    A roadmap for computational fluid dynamics (CFD) code validation is developed. The elements of the roadmap are consistent with air-breathing vehicle design requirements and related to the important flow path components: forebody, inlet, combustor, and nozzle. Building block and benchmark validation experiments are identified along with their test conditions and measurements. Based on an evaluation criteria, recommendations for an initial CFD validation data base are given and gaps identified where future experiments would provide the needed validation data.

  11. Efficient Turbulence Modeling for CFD Wake Simulations

    DEFF Research Database (Denmark)

    van der Laan, Paul

    Wind turbine wakes can cause 10-20% annual energy losses in wind farms, and wake turbulence can decrease the lifetime of wind turbine blades. One way of estimating these effects is the use of computational fluid dynamics (CFD) to simulate wind turbines wakes in the atmospheric boundary layer. Since...... this flow is in the high Reynolds number regime, it is mainly dictated by turbulence. As a result, the turbulence modeling in CFD dominates the wake characteristics, especially in Reynolds-averaged Navier-Stokes (RANS). The present work is dedicated to study and develop RANS-based turbulence models...... verified with a grid dependency study. With respect to the standard k-ε EVM, the k-ε- fp EVM compares better with measurements of the velocity deficit, especially in the near wake, which translates to improved power deficits of the first wind turbines in a row. When the CFD metholody is applied to a large...

  12. Experimental CFD grade data for stratified two-phase flows

    Energy Technology Data Exchange (ETDEWEB)

    Vallee, Christophe, E-mail: c.vallee@fzd.d [Forschungszentrum Dresden-Rossendorf e.V., Institute of Safety Research, D-01314 Dresden (Germany); Lucas, Dirk; Beyer, Matthias; Pietruske, Heiko; Schuetz, Peter; Carl, Helmar [Forschungszentrum Dresden-Rossendorf e.V., Institute of Safety Research, D-01314 Dresden (Germany)

    2010-09-15

    Stratified two-phase flows were investigated at two test facilities with horizontal test-sections. For both, rectangular channel cross-sections were chosen to provide optimal observation possibilities for the application of optical measurement techniques. In order to show the local flow structure, high-speed video observation was applied, which delivers the high-resolution in space and time needed for CFD code validation. The first investigations were performed in the Horizontal Air/Water Channel (HAWAC), which is made of acrylic glass and allows the investigation of air/water co-current flows at atmospheric pressure and room temperature. At the channel inlet, a special device was designed for well-defined and adjustable inlet boundary conditions. For the quantitative analysis of the optical measurements performed at the HAWAC, an algorithm was developed to recognise the stratified interface in the camera frames. This allows to make statistical treatments for comparison with CFD calculation results. As an example, the unstable wave growth leading to slug flow is shown from the test-section inlet. Moreover, the hydraulic jump as the quasi-stationary discontinuous transition between super- and subcritical flow was investigated in this closed channel. The structure of the hydraulic jump over time is revealed by the calculation of the probability density of the water level. A series of experiments show that the hydraulic jump profile and its position from the inlet vary substantially with the inlet boundary conditions due to the momentum exchange between the phases. The second channel is built in the pressure chamber of the TOPFLOW test facility, which is used to perform air/water and steam/water experiments at pressures of up to 5.0 MPa and temperatures of up to 264 {sup o}C, but under pressure equilibrium with the vessel inside. In the present experiment, the test-section represents a flat model of the hot leg of the German Konvoi pressurised water reactor scaled at

  13. Experimental CFD grade data for stratified two-phase flows

    International Nuclear Information System (INIS)

    Vallee, Christophe; Lucas, Dirk; Beyer, Matthias; Pietruske, Heiko; Schuetz, Peter; Carl, Helmar

    2010-01-01

    Stratified two-phase flows were investigated at two test facilities with horizontal test-sections. For both, rectangular channel cross-sections were chosen to provide optimal observation possibilities for the application of optical measurement techniques. In order to show the local flow structure, high-speed video observation was applied, which delivers the high-resolution in space and time needed for CFD code validation. The first investigations were performed in the Horizontal Air/Water Channel (HAWAC), which is made of acrylic glass and allows the investigation of air/water co-current flows at atmospheric pressure and room temperature. At the channel inlet, a special device was designed for well-defined and adjustable inlet boundary conditions. For the quantitative analysis of the optical measurements performed at the HAWAC, an algorithm was developed to recognise the stratified interface in the camera frames. This allows to make statistical treatments for comparison with CFD calculation results. As an example, the unstable wave growth leading to slug flow is shown from the test-section inlet. Moreover, the hydraulic jump as the quasi-stationary discontinuous transition between super- and subcritical flow was investigated in this closed channel. The structure of the hydraulic jump over time is revealed by the calculation of the probability density of the water level. A series of experiments show that the hydraulic jump profile and its position from the inlet vary substantially with the inlet boundary conditions due to the momentum exchange between the phases. The second channel is built in the pressure chamber of the TOPFLOW test facility, which is used to perform air/water and steam/water experiments at pressures of up to 5.0 MPa and temperatures of up to 264 o C, but under pressure equilibrium with the vessel inside. In the present experiment, the test-section represents a flat model of the hot leg of the German Konvoi pressurised water reactor scaled at 1

  14. A coupled CFD and wake model simulation of helicopter rotor in hover

    Science.gov (United States)

    Zhao, Qinghe; Li, Xiaodong

    2018-03-01

    The helicopter rotor wake plays a dominant role since it affects the flow field structure. It is very difficult to predict accurately of the flow-field. The numerical dissipation is so excessive that it eliminates the vortex structure. A hybrid method of CFD and prescribed wake model was constructed by applying the prescribed wake model as much as possible. The wake vortices were described as a single blade tip vortex in this study. The coupling model is used to simulate the flow field. Both non-lifting and lifting cases have been calculated with subcritical and supercritical tip Mach numbers. Surface pressure distributions are presented and compared with experimental data. The calculated results agree well with the experimental data.

  15. CFD analyses of steam and hydrogen distribution in a nuclear power plant

    International Nuclear Information System (INIS)

    Siccama, N.B.; Houkema, M.; Komen, E.M.J.

    2003-01-01

    A detailed three-dimensional Computational Fluid Dynamics (CFD) model of the containment of the nuclear power plant has been prepared in order to assess possible multidimensional phenomena. In a first code-to-code comparison step, the CFD model has been used to compute a reference accident scenario which has been analysed earlier with the lumped parameter code SPECTRA. The CFD results compare qualitatively well with the SPECTRA results. Subsequently, the actual steam jet from the primary system has been modelled in the CFD code in order to determine the hydrogen distribution for this realistically modelled source term. Based on the computed hydrogen distributions, it has been determined when use of lumped parameter codes is allowed and when use of CFD codes is required. (author)

  16. A multiscale numerical algorithm for heat transfer simulation between multidimensional CFD and monodimensional system codes

    Science.gov (United States)

    Chierici, A.; Chirco, L.; Da Vià, R.; Manservisi, S.; Scardovelli, R.

    2017-11-01

    Nowadays the rapidly-increasing computational power allows scientists and engineers to perform numerical simulations of complex systems that can involve many scales and several different physical phenomena. In order to perform such simulations, two main strategies can be adopted: one may develop a new numerical code where all the physical phenomena of interest are modelled or one may couple existing validated codes. With the latter option, the creation of a huge and complex numerical code is avoided but efficient methods for data exchange are required since the performance of the simulation is highly influenced by its coupling techniques. In this work we propose a new algorithm that can be used for volume and/or boundary coupling purposes for both multiscale and multiphysics numerical simulations. The proposed algorithm is used for a multiscale simulation involving several CFD domains and monodimensional loops. We adopt the overlapping domain strategy, so the entire flow domain is simulated with the system code. We correct the system code solution by matching averaged inlet and outlet fields located at the boundaries of the CFD domains that overlap parts of the monodimensional loop. In particular we correct pressure losses and enthalpy values with source-sink terms that are imposed in the system code equations. The 1D-CFD coupling is a defective one since the CFD code requires point-wise values on the coupling interfaces and the system code provides only averaged quantities. In particular we impose, as inlet boundary conditions for the CFD domains, the mass flux and the mean enthalpy that are calculated by the system code. With this method the mass balance is preserved at every time step of the simulation. The coupling between consecutive CFD domains is not a defective one since with the proposed algorithm we can interpolate the field solutions on the boundary interfaces. We use the MED data structure as the base structure where all the field operations are

  17. Case studies from the REHVA CFD guide book

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    2008-01-01

    This paper presents CFD predictions which are used at different levels, from the evaluation of an idea to the design of a system, or for the analysing work on an existing building.......This paper presents CFD predictions which are used at different levels, from the evaluation of an idea to the design of a system, or for the analysing work on an existing building....

  18. The application of CFD to hydrogen risk analysis in nuclear power plants

    International Nuclear Information System (INIS)

    Wang Hui; Han Xu; Chang Meng; Wang Xiaofeng; Wang Shuguo; Lu Xinhua; Wu Lin

    2013-01-01

    Status of the hydrogen risk analysis method is systemically summarized in this paper and the advantages and limits of CFD (Computational Fluid Dynamic) in hydrogen risk analysis is discussed. The international experimental programs on the CFD hydrogen risk analysis are introduced in this paper. The application of CFD to nuclear power plant (NPP) hydrogen risk analysis is introduced in detail by taking EPR and Ling'ao NPP for example. In these bases, the CFD development prospect of hydrogen risk analysis is also summarized in this paper. (authors)

  19. CFD modeling and experience of waste-to-energy plant burning waste wood

    DEFF Research Database (Denmark)

    Rajh, B.; Yin, Chungen; Samec, N.

    2013-01-01

    Computational Fluid Dynamics (CFD) is being increasingly used in industry for in-depth understanding of the fundamental mixing, combustion, heat transfer and pollutant formation in combustion processes and for design and optimization of Waste-to-Energy (WtE) plants. In this paper, CFD modeling...... the conversion of the waste wood in the fuel bed on the grate, which provides the appropriate inlet boundary condition for the freeboard 3D CFD simulation. The CFD analysis reveals the detailed mixing and combustion characteristics in the waste wood-fired furnace, pinpointing how to improve the design...

  20. Application of Simple CFD Models in Smoke Ventilation Design

    DEFF Research Database (Denmark)

    Brohus, Henrik; Nielsen, Peter Vilhelm; la Cour-Harbo, Hans

    2004-01-01

    The paper examines the possibilities of using simple CFD models in practical smoke ventilation design. The aim is to assess if it is possible with a reasonable accuracy to predict the behaviour of smoke transport in case of a fire. A CFD code mainly applicable for “ordinary” ventilation design...

  1. Recent results of three-dimensional CFD simulations of coolant mixing in VVER-440/213 reactor pressure vessel

    International Nuclear Information System (INIS)

    Kiss, B.; Boros, I.; Aszodi, A.

    2008-01-01

    The Budapest University of Technology and Economics, Institute of Nuclear Techniques has been working since 2001 on the three-dimensional CFD model of the reactor pressure vessel of the VVER-440 type reactor. During this time period - due to the development of the available computational capacity - a very complex and detailed model of the RPV has been developed. The aim of the construction of the new model is to describe further internal structures of the RPV (e.g. correct modeling of brake tubes, or internals in the upper mixing chamber) and to perform an extensive sensitivity analysis on the different modeling and calculation parameters (e.g. porous region models vs. detailed modeling, or n different turbulence models). The new model can be applied for steady state calculation during normal operational condition and for different transient analyses as well. One interesting application is the participation in a planned benchmark exercise on the start-up of the sixth main coolant pump, which is aimed to compare the capabilities of mixing models of one-dimensional system codes with the results of CFD simulation. (authors)

  2. Application perspectives of simulation techniques CFD in nuclear power plants

    International Nuclear Information System (INIS)

    Galindo G, I. F.

    2013-10-01

    The scenarios simulation in nuclear power plants is usually carried out with system codes that are based on concentrated parameters networks. However situations exist in some components where the flow is predominantly 3-D, as they are the natural circulation, mixed and stratification phenomena. The simulation techniques of computational fluid dynamics (CFD) have the potential to simulate these flows numerically. The use of CFD simulations embraces many branches of the engineering and continues growing, however, in relation to its application with respect to the problems related with the safety in nuclear power plants, has a smaller development, although is accelerating quickly and is expected that in the future they play a more emphasized paper in the analyses. A main obstacle to be able to achieve a general acceptance of the CFD is that the simulations should have very complete validation studies, sometimes not available. In this article a general panorama of the state of the methods application CFD in nuclear power plants is presented and the problem associated to its routine application and acceptance, including the view point of the regulatory authorities. Application examples are revised in those that the CFD offers real benefits and are also presented two illustrative study cases of the application of CFD techniques. The case of a water recipient with a heat source in its interior, similar to spent fuel pool of a nuclear power plant is presented firstly; and later the case of the Boron dilution of a water volume that enters to a nuclear reactor is presented. We can conclude that the CFD technology represents a very important opportunity to improve the phenomena understanding with a strong component 3-D and to contribute in the uncertainty reduction. (Author)

  3. Computational Fluid Dynamics (CFD) Analyses in Support of Space Shuttle Main Engine (SSME) Heat Exchanger (HX) Vane Cracking Investigation

    Science.gov (United States)

    Garcia, Roberto; Benjamin, Theodore G.; Cornelison, J.; Fredmonski, A. J.

    1993-01-01

    Integration issues involved with installing the alternate turbopump (ATP) High Pressure Oxygen Turbopump (HPOTP) into the SSME have raised questions regarding the flow in the HPOTP turnaround duct (TAD). Steady-state Navier-Stokes CFD analyses have been performed by NASA and Pratt & Whitney (P&W) to address these questions. The analyses have consisted of two-dimensional axisymmetric calculations done at Marshall Space Flight Center and three-dimensional calculations performed at P&W. These analyses have identified flowfield differences between the baseline ATP and the Rocketdyne configurations. The results show that the baseline ATP configuration represents a more severe environment to the inner HX guide vane. This vane has limited life when tested in conjunction with the ATP but infinite life when tested with the current SSME HPOTP. The CFD results have helped interpret test results and have been used to assess proposed redesigns. This paper includes details of the axisymmetric model, its results, and its contribution towards resolving the problem.

  4. The role of CFD computer analyses in hydrogen safety management

    International Nuclear Information System (INIS)

    Komen, E.M.J; Visser, D.C; Roelofs, F.; Te Lintelo, J.G.T

    2014-01-01

    The risks of hydrogen release and combustion during a severe accident in a light water reactor have attracted considerable attention after the Fukushima accident in Japan. Reliable computer analyses are needed for the optimal design of hydrogen mitigation systems, like e.g. passive autocatalytic recombiners (PARs), and for the assessment of the associated residual risk of hydrogen combustion. Traditionally, so-called Lumped Parameter (LP) computer codes are being used for these purposes. In the last decade, significant progress has been made in the development, validation, and application of more detailed, three-dimensional Computational Fluid Dynamics (CFD) simulations for hydrogen safety analyses. The objective of the current paper is to address the following questions: - When are CFD computer analyses needed complementary to the traditional LP code analyses for hydrogen safety management? - What is the validation status of the CFD computer code for hydrogen distribution, mitigation, and combustion analyses? - Can CFD computer analyses nowadays be executed in practical and reliable way for full scale containments? The validation status and reliability of CFD code simulations will be illustrated by validation analyses performed for experiments executed in the PANDA, THAI, and ENACCEF facilities. (authors)

  5. CFD for hypersonic propulsion

    Science.gov (United States)

    Povinelli, Louis A.

    1991-01-01

    An overview is given of research activity on the application of computational fluid dynamics (CDF) for hypersonic propulsion systems. After the initial consideration of the highly integrated nature of air-breathing hypersonic engines and airframe, attention is directed toward computations carried out for the components of the engine. A generic inlet configuration is considered in order to demonstrate the highly three dimensional viscous flow behavior occurring within rectangular inlets. Reacting flow computations for simple jet injection as well as for more complex combustion chambers are then discussed in order to show the capability of viscous finite rate chemical reaction computer simulations. Finally, the nozzle flow fields are demonstrated, showing the existence of complex shear layers and shock structure in the exhaust plume. The general issues associated with code validation as well as the specific issue associated with the use of CFD for design are discussed. A prognosis for the success of CFD in the design of future propulsion systems is offered.

  6. A fast converging CFD model for thermal hydraulic analysis of gas cooled reactor cores

    International Nuclear Information System (INIS)

    Chen, Gary; Anghaie, Samim

    1999-01-01

    A computational fluid dynamics (CFD) approach to the solution of Navier-Stokes equations for the thermal and flow fields of gas cooled reactor cores is presented. An implicit-explicit MacCormack method based on finite volume discretization scheme, in conjunction with the Gauss-Seidel line iteration procedure is utilized to solve axisymmetric, thin-layer Navier-Stokes equations. This numerical method requires only the inversion of block bidiagonal systems rather than block tridiagonal systems, thus yielding savings in computer time and storage requirements. A two-layer algebraic eddy viscosity turbulence model is used in this study. The effects of turbulence are simulated in terms of the eddy viscosity coefficient, which is calculated for an inner and an outer region separately. An enthalpy-rebalancing scheme is implemented to allow the convergence solutions to be obtained with the application of a wall heat flux. The detailed computational analysis developed in this work is used to evaluate many different Nusselt number equations, property corrections, and axial distance corrections. The calculation based on this CFD model is compared with other published results. The good agreement indicates the usefulness of the presented model for the prediction of flow and temperature distributions for gas cooled reactor cores. (author)

  7. Flask fluid flow simulation using CFD

    International Nuclear Information System (INIS)

    Swindlehurst, W.E.; Livesey, E.; Worthington, D.

    1989-01-01

    BNFL and its subsidiary Company, PNTL, design and operate waterfilled LWR fuel transport flasks for the international transport of irradiated fuel. Although some 150 flasks are currently in operation, new flask designs are being developed. As part of the supporting R and D program, Computational Fluid Dynamics (CFD) codes are being investigated as a means of predicting fluid movements and temperatures within the complex internal geometry of flasks. The ability to simulate fluid flow is particularly important when convection heat transfer is significant. Although obviously relevant to water filled flasks, the technique is applicable to dry flask thermal assessments (where experience shows that convection heat transfer is often underestimated). Computational Fluid Dynamics has emerged in recent years as an important technique in engineering design and safety assessments. Cheaper computing and the development of general CFD codes allows complex engineering structures to be analyzed. However, because of this complexity, it is essential that the application and associated modeling assumptions are critically reviewed. To assess the ability of a CFD code to model flask internals, the code PHOENICS has been used to model the fluid movements in a BNFL Excellox-type flask and the results compared with test data

  8. MODELLING MANTLE TANKS FOR SDHW SYSTEMS USING PIV AND CFD

    DEFF Research Database (Denmark)

    Shah, Louise Jivan; Morrison, G.L.; Behnia, Masud

    1999-01-01

    Characteristics of vertical mantle heat exchanger tanks for SDHW systems have been investigated experimentally and theoretically using particle image velocimetry (PIV) and CFD modelling. A glass model of a mantle heat exchanger tank was constructed so that the flow distribution in the mantle could...... be studied using the PIV test facility. Two transient three-dimensional CFD-models of the glass model mantle tank were developed using the CFD-programmes CFX and FLUENT.The experimental results illustrate that the mantle flow structure in the mantle is complicated and the distribution of flow in the mantle...

  9. Numerical analysis for simulation of condensing vapor bubble using CFD-ACE+

    International Nuclear Information System (INIS)

    Goyal, P.; Dutta, Anu; Singh, R.K.

    2014-01-01

    The motion of bubbles is very complex. They may be subject to break-up or coalescence and may appear to move with a spiraling, zigzagging or rocking behavior. Recently, many studies have been carried out to numerically simulate the rising bubble in various conditions by using VOF approach. However, all the above studies were limited to adiabatic bubble where heat and mass transfer between the phases were not considered. In the present work, an attempt was made to capture the behaviour of condensing bubble flowing in a channel, by using commercial CFD code CFD-ACE+ through VOF model. A User-Defined Function was developed to simulate interfacial heat and mass transfer during condensation. The effect of condensation on bubble behavior was analyzed by comparing the behavior of condensing bubble with that of adiabatic bubble. For validation of CFD-ACE UDF of bubble condensation, a comparison was made with the literature quoted experimental data and it agreed well. Through this work an emphasis was put on VOF module along with the development of an UDF for bubble condensation in CFD-ACE+ code. This theoretical study is motivated by the future CFD application and the intent to investigate the capabilities of the CFD-ACE+ package. (author)

  10. The Brent Contract for Differences (CFD)

    International Nuclear Information System (INIS)

    Barrera-Rey, F.; Seymour, A.

    1996-01-01

    The market for Brent Contracts-for-Differences (CFDs) emerged as early as 1988 but its significant development did not occur until 1992. By financial market standards, however, this span of life is fairly long. Yet the characteristics and role of this oil trading instrument have not been seriously studied. This study aims at filling a gap in research on the Brent market complex which includes spot trades, a 15-day forward and futures contracts, various derivatives and, finally, the less well documented CFD. Chapters 2 and 3 aim to describe and explain the characteristics of the CFD market, in particular the evolution in contract terms and the composition of participants. (UK)

  11. Prediction of fire growth on furniture using CFD

    Science.gov (United States)

    Pehrson, Richard David

    A fire growth calculation method has been developed that couples a computational fluid dynamics (CFD) model with bench scale cone calorimeter test data for predicting the rate of flame spread on compartment contents such as furniture. The commercial CFD code TASCflow has been applied to solve time averaged conservation equations using an algebraic multigrid solver with mass weighted skewed upstream differencing for advection. Closure models include k-e for turbulence, eddy breakup for combustion following a single step irreversible reaction with Arrhenius rate constant, finite difference radiation transfer, and conjugate heat transfer. Radiation properties are determined from concentrations of soot, CO2 and H2O using the narrow band model of Grosshandler and exponential wide band curve fit model of Modak. The growth in pyrolyzing area is predicted by treating flame spread as a series of piloted ignitions based on coupled gas-fluid boundary conditions. The mass loss rate from a given surface element follows the bench scale test data for input to the combustion prediction. The fire growth model has been tested against foam-fabric mattresses and chairs burned in the furniture calorimeter. In general, agreement between model and experiment for peak heat release rate (HRR), time to peak HRR, and total energy lost is within +/-20%. Used as a proxy for the flame spread velocity, the slope of the HRR curve predicted by model agreed with experiment within +/-20% for all but one case.

  12. Assessment of CFD Codes for Nuclear Reactor Safety Problems - Revision 2

    International Nuclear Information System (INIS)

    Smith, B.L.; Andreani, M.; Bieder, U.; Ducros, F.; Bestion, D.; Graffard, E.; Heitsch, M.; Scheuerer, M.; Henriksson, M.; Hoehne, T.; Houkema, M.; Komen, E.; Mahaffy, J.; Menter, F.; Moretti, F.; Morii, T.; Muehlbauer, P.; Rohde, U.; Krepper, E.; Song, C.H.; Watanabe, T.; Zigh, G.; Boyd, C.F.; Archambeau, F.; Bellet, S.; Munoz-Cobo, J.M.; Simoneau, J.P.

    2015-01-01

    Following recommendations made at an 'Exploratory Meeting of Experts to Define an Action Plan on the Application of Computational Fluid Dynamics (CFD) Codes to Nuclear Reactor Safety (NRS) Problems', held in Aix-en-Provence, France, 15-16 May, 2002, and a follow-up meeting 'Use of Computational Fluid Dynamics (CFD) Codes for Safety Analysis of Reactor Systems including Containment', which took place in Pisa on 11-14 Nov., 2002, a CSNI action plan was drawn up which resulted in the creation of three Writing Groups, with mandates to perform the following tasks: (1) Provide a set of guidelines for the application of CFD to NRS problems; (2) Evaluate the existing CFD assessment bases, and identify gaps that need to be filled; (3) Summarise the extensions needed to CFD codes for application to two-phase NRS problems. Work began early in 2003. In the case of Writing Group 2 (WG2), a preliminary report was submitted to Working Group on the Analysis and Management of Accidents (WGAMA) in September 2004 that scoped the work needed to be carried out to fulfil its mandate, and made recommendations on how to achieve the objective. A similar procedure was followed by the other two groups, and in January 2005 all three groups were reformed to carry out their respective tasks. In the case of WG2, this resulted in the issue of a CSNI report (NEA/CSNI/R(2007)13), issued in January 2008, describing the work undertaken. The writing group met on average twice per year during the period March 2005 to May 2007, and coordinated activities strongly with the sister groups WG1 (Best Practice Guidelines) and WG3 (Multiphase Extensions). The resulting document prepared at the end of this time still represents the core of the present revised version, though updates have been made as new material has become available. After some introductory remarks, Chapter 3 lists twenty-three (23) NRS issues for which it is considered that the application of CFD would bring real benefits

  13. CFD study of leakage flows in shroud cavities of a compressor impeller

    Science.gov (United States)

    Soldatova, K.

    2017-08-01

    The flow character in a gap between shroud disc of an impeller and a stator surface (shroud cavity) influences disc friction loss, labyrinth seal loss (parasitic losses) and thrust force. Flow calculations inside the shroud cavity of a model of centrifugal compressor stage and its labyrinth seal in a range of flow rates and axial width and radial gap are presented. The results are presented in terms of non-dimensional coefficients of flow, disc friction and seal leakage losses coefficients and pressure coefficient. The distributions meridional and tangential flow velocities correspond to the continuity and equilibrium equations - flow radial circulation exists in wide cavity and is absent in narrow cavities. The radial pressure distributions as measured and calculated are not fully comparable. The possible reason is that CFD-calculated leakage coefficient is less than calculated by A.Stodola formula. The influence of a cavity width on the losses and the thrust force requires a balanced design.

  14. Assessment of Computational Fluid Dynamics (CFD) Models for Shock Boundary-Layer Interaction

    Science.gov (United States)

    DeBonis, James R.; Oberkampf, William L.; Wolf, Richard T.; Orkwis, Paul D.; Turner, Mark G.; Babinsky, Holger

    2011-01-01

    A workshop on the computational fluid dynamics (CFD) prediction of shock boundary-layer interactions (SBLIs) was held at the 48th AIAA Aerospace Sciences Meeting. As part of the workshop numerous CFD analysts submitted solutions to four experimentally measured SBLIs. This paper describes the assessment of the CFD predictions. The assessment includes an uncertainty analysis of the experimental data, the definition of an error metric and the application of that metric to the CFD solutions. The CFD solutions provided very similar levels of error and in general it was difficult to discern clear trends in the data. For the Reynolds Averaged Navier-Stokes methods the choice of turbulence model appeared to be the largest factor in solution accuracy. Large-eddy simulation methods produced error levels similar to RANS methods but provided superior predictions of normal stresses.

  15. Complot test section outlet CFD optimization (pre - test and dimensioning)

    International Nuclear Information System (INIS)

    Profir, M. M.; Moreau, V.; Kennedy, G.

    2013-01-01

    In the framework of the FP7 MAXSIMA European project, the COMPLOT (COMPonent LOop Testing) LBE experimental facility is employed for thermal-hydraulic experiments aimed to test and qualify, among other components, a buoyancy driven safety/control rods (SR/CR) system, as key components for the safe operation of the MYRRHA reactor. This paper focuses mainly on a simplified CFD representation of the SR test section outlet in order to optimise it for the testing program. Parametric cases, associated with different positions of the SR assembly have been set up and analysed. A quasi-static analysis has been performed for each case, accounting for the LBE volume displaced by the insertion of the SR bundle, by introducing appropriately positioned additional mass sources. Velocity and pressure fields, as well as pressure drop magnitudes and mass flow rates through relevant guide tube hole outlets have been calculated and compared. The CFD analysis proved that the outer boundary of the test section does not impact the expected performance of the SR (rapid transient downward insertion). Preliminary simulations reproducing the timely repositioning of the SR/CR in COMPLOT using procedures of automatic volume mesh regeneration, consistently with the rod imposed displacement, are illustrated. (authors)

  16. A computational fluid dynamics (CFD) study of WEB-treated aneurysms: Can CFD predict WEB "compression" during follow-up?

    Science.gov (United States)

    Caroff, Jildaz; Mihalea, Cristian; Da Ros, Valerio; Yagi, Takanobu; Iacobucci, Marta; Ikka, Léon; Moret, Jacques; Spelle, Laurent

    2017-07-01

    Recent reports have revealed a worsening of aneurysm occlusion between WEB treatment baseline and angiographic follow-up due to "compression" of the device. We utilized computational fluid dynamics (CFD) in order to determine whether the underlying mechanism of this worsening is flow related. We included data from all consecutive patients treated in our institution with a WEB for unruptured aneurysms located either at the middle cerebral artery or basilar tip. The CFD study was performed using pre-operative 3D rotational angiography. From digital subtraction follow-up angiographies patients were dichotomized into two groups: one with WEB "compression" and one without. We performed statistical analyses to determine a potential correlation between WEB compression and CFD inflow ratio. Between July 2012 and June 2015, a total of 22 unruptured middle cerebral artery or basilar tip aneurysms were treated with a WEB device in our department. Three patients were excluded from the analysis and the mean follow-up period was 17months. Eleven WEBs presented "compression" during follow-up. Interestingly, device "compression" was statistically correlated to the CFD inflow ratio (P=0.018), although not to aneurysm volume, aspect ratio or neck size. The mechanisms underlying the worsening of aneurysm occlusion in WEB-treated patients due to device compression are most likely complex as well as multifactorial. However, it is apparent from our pilot study that a high arterial inflow is, at least, partially involved. Further theoretical and animal research studies are needed to increase our understanding of this phenomenon. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  17. Development of Mitsubishi high thermal performance grid 1 - CFD applicability for thermal hydraulic design

    International Nuclear Information System (INIS)

    Ikeda, K.; Hoshi, M.

    2001-01-01

    Mitsubishi applied the Computational Fluid Dynamics (CFD) evaluation method for designing of the new lower pressure loss and higher DNB performance grid spacer. Reduction of pressure loss of the grid has been estimated by CFD. Also, CFD has been developed as a design tool to predict the coolant mixing ability of vane structures, that is to compare the relative peak spot temperatures around fuel rods at the same heat flux condition. These evaluations have been reflected to the new grid spacer design. The prototype grid was manufactured and some flow tests were performed to examine the thermal hydraulic performance, which were predicted by CFD. The experimental data of pressure loss was in good agreement with CFD prediction. The CFD prediction of flow behaviors at downstream of the mixing vanes was verified by detail cross-flow measurements at rod gaps by the rod LDV system. It is concluded that the applicability of the CFD evaluation method for the thermal hydraulic design of the grid is confirmed. (authors)

  18. Perspectives on CFD analysis in nuclear reactor regulation

    Energy Technology Data Exchange (ETDEWEB)

    Boyd, Christopher, E-mail: christopher.boyd@nrc.gov

    2016-04-01

    The U.S. Nuclear Regulatory Commission is tasked with ensuring that the commercial use of nuclear materials in the United States is safe. This includes the review and evaluation of submitted analyses that support the safety justification for specific reactor-system components or scenarios. Typically these analyses involve the use of codes that have a proven history of validation and acceptance for the specific application of interest. The use of computational fluid dynamics (CFD) has not been as widespread in regulatory activities and the experience level with acceptance is more limited. The ever-increasing capacity of computers, along with the growing number of capable analysts, ensures us that CFD applications will continue to grow in usage for nuclear safety analysis. The challenge ahead is to ensure that these tools are properly validated and applied in order to build up the necessary evidence for more common acceptance in regulatory processes. The challenges include a continuation of the development and maintenance of best-practice guidance, development of problem-specific CFD-grade benchmark studies, the application of verification and validation techniques, and the development of practical treatments for uncertainties and scaling. Through these efforts, it is anticipated that CFD methods will continue to gain acceptance for use in nuclear reactor safety applications.

  19. Investigation on a coupled CFD/DSMC method for continuum-rarefied flows

    Science.gov (United States)

    Tang, Zhenyu; He, Bijiao; Cai, Guobiao

    2012-11-01

    The purpose of the present work is to investigate the coupled CFD/DSMC method using the existing CFD and DSMC codes developed by the authors. The interface between the continuum and particle regions is determined by the gradient-length local Knudsen number. A coupling scheme combining both state-based and flux-based coupling methods is proposed in the current study. Overlapping grids are established between the different grid systems of CFD and DSMC codes. A hypersonic flow over a 2D cylinder has been simulated using the present coupled method. Comparison has been made between the results obtained from both methods, which shows that the coupled CFD/DSMC method can achieve the same precision as the pure DSMC method and obtain higher computational efficiency.

  20. Wind Loads on Ships and Offshore Structures Estimated by CFD

    DEFF Research Database (Denmark)

    Aage, Christian; Hvid, S.L.; Hughes, P.H.

    1997-01-01

    Wind loads on ships and offshore structures could until recently be determined only by model tests, or by statistical methods based on model tests. By the development of Computational Fluid Dynamics or CFD there is now a realistic computational alternative available. In this paper, wind loads...... on a seagoing ferry and on a semisubmersible offshore platform have been estimated by CFD. The results have been compared with wind tunnel model tests and, for the ferry, a few full-scale measurements, and good agreement is obtained. The CFD method offers the possibility of a computational estimate of scale...... effects related to wind tunnel model testing. An example of such an estimate on the ferry is discussed. Due to the time involved in generating the computational mesh and in computing the solution, the CFD method is not at the moment economically competitive to routine wind tunnel model testing....

  1. Cross cutting CFD support to innovative reactor design

    International Nuclear Information System (INIS)

    Roelofs, Ferry

    2009-01-01

    Several innovative technologies are under consideration in the world for nuclear energy production. The considered reactor systems apply either gas, sodium, lead, lead-bismuth, supercritical water, or molten salt as coolant. Therefore, methods shall be developed to determine the viability of such systems, but also to support the design of these innovative reactor systems. Computational Fluid Dynamics (CFD) is becoming more and more integrated in the daily practice of thermal-hydraulics researchers and designers. Therefore, it is very important to develop modelling approaches for the application of CFD to the specific requirements for innovative reactors. As many of these innovative reactor designs under consideration are operated using other coolants than water, one has to be careful in adopting methods which are developed for water as a coolant. Cross-cutting CFD challenges, methods and applications are presented for innovative reactors. (author)

  2. Unstructured Grid Adaptation: Status, Potential Impacts, and Recommended Investments Toward CFD Vision 2030

    Science.gov (United States)

    Park, Michael A.; Krakos, Joshua A.; Michal, Todd; Loseille, Adrien; Alonso, Juan J.

    2016-01-01

    Unstructured grid adaptation is a powerful tool to control discretization error for Computational Fluid Dynamics (CFD). It has enabled key increases in the accuracy, automation, and capacity of some fluid simulation applications. Slotnick et al. provides a number of case studies in the CFD Vision 2030 Study: A Path to Revolutionary Computational Aerosciences to illustrate the current state of CFD capability and capacity. The authors forecast the potential impact of emerging High Performance Computing (HPC) environments forecast in the year 2030 and identify that mesh generation and adaptivity continue to be significant bottlenecks in the CFD work flow. These bottlenecks may persist because very little government investment has been targeted in these areas. To motivate investment, the impacts of improved grid adaptation technologies are identified. The CFD Vision 2030 Study roadmap and anticipated capabilities in complementary disciplines are quoted to provide context for the progress made in grid adaptation in the past fifteen years, current status, and a forecast for the next fifteen years with recommended investments. These investments are specific to mesh adaptation and impact other aspects of the CFD process. Finally, a strategy is identified to diffuse grid adaptation technology into production CFD work flows.

  3. Enhancement of CFD validation exercise along the roof profile of a low-rise building

    Science.gov (United States)

    Deraman, S. N. C.; Majid, T. A.; Zaini, S. S.; Yahya, W. N. W.; Abdullah, J.; Ismail, M. A.

    2018-04-01

    The aim of this study is to enhance the validation of CFD exercise along the roof profile of a low-rise building. An isolated gabled-roof house having 26.6° roof pitch was simulated to obtain the pressure coefficient around the house. Validation of CFD analysis with experimental data requires many input parameters. This study performed CFD simulation based on the data from a previous study. Where the input parameters were not clearly stated, new input parameters were established from the open literatures. The numerical simulations were performed in FLUENT 14.0 by applying the Computational Fluid Dynamics (CFD) approach based on steady RANS equation together with RNG k-ɛ model. Hence, the result from CFD was analysed by using quantitative test (statistical analysis) and compared with CFD results from the previous study. The statistical analysis results from ANOVA test and error measure showed that the CFD results from the current study produced good agreement and exhibited the closest error compared to the previous study. All the input data used in this study can be extended to other types of CFD simulation involving wind flow over an isolated single storey house.

  4. A Hybrid Parallel Preconditioning Algorithm For CFD

    Science.gov (United States)

    Barth,Timothy J.; Tang, Wei-Pai; Kwak, Dochan (Technical Monitor)

    1995-01-01

    A new hybrid preconditioning algorithm will be presented which combines the favorable attributes of incomplete lower-upper (ILU) factorization with the favorable attributes of the approximate inverse method recently advocated by numerous researchers. The quality of the preconditioner is adjustable and can be increased at the cost of additional computation while at the same time the storage required is roughly constant and approximately equal to the storage required for the original matrix. In addition, the preconditioning algorithm suggests an efficient and natural parallel implementation with reduced communication. Sample calculations will be presented for the numerical solution of multi-dimensional advection-diffusion equations. The matrix solver has also been embedded into a Newton algorithm for solving the nonlinear Euler and Navier-Stokes equations governing compressible flow. The full paper will show numerous examples in CFD to demonstrate the efficiency and robustness of the method.

  5. Quantitative Analysis of Accuracy of Voidage Computations in CFD-DEM Simulations

    Directory of Open Access Journals (Sweden)

    H. A. Khawaja

    2012-06-01

    Full Text Available CFD-DEM (Computational Fluid Dynamics – Discrete Element Modelling is a two-phase flow numerical modelling technique, where the Eulerian method is used for the fluid and the Lagrangian method for the particles. The two phases are coupled by a fluid-particle interaction force (i.e. drag force which is computed using a correlation. In a two-phase flow, one critical parameter is the voidage (or void fraction, which is defined as the ratio of the volume occupied by the fluid to the total volume. In a CFD-DEM simulation the local voidage is computed by calculating the volume of particles in a given fluid cell. For spherical particles, this computation is difficult when a particle is on the boundary of fluid cells. In this case, it is usual to compute the volume of a particle in a fluid cell approximately. One such approximation divides the volume of a particle into each cell in the same ratio as an equivalent cube of width equal to the particle diameter. Whilst this approach is computationally straight forward, the approximation introduces an error in the voidage computation. Here we estimate the error by comparing the approximate volume calculation with an exact (numerical computation of the volume of a particle in a fluid cell. The results show that the error varies with the position of the particle relative to the cell boundary. A new approach is suggested which limits the error to less than 2.5 %, without significantly increasing the computational complexity.

  6. New CFD tools to evaluate nasal airflow.

    Science.gov (United States)

    Burgos, M A; Sanmiguel-Rojas, E; Del Pino, C; Sevilla-García, M A; Esteban-Ortega, F

    2017-08-01

    Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. As currently CFD is not a usual tool for rhinologists, a group of engineers in collaboration with experts in Rhinology have developed a very intuitive CFD software. The program MECOMLAND ® only required snapshots from the patient's cross-sectional (tomographic) images, being the output those results originated by CFD, such as airflow distributions, velocity profiles, pressure, temperature, or wall shear stress. This is useful complementary information to cover diagnosis, prognosis, or follow-up of nasal pathologies based on quantitative magnitudes linked to airflow. In addition, the user-friendly environment NOSELAND ® helps the medical assessment significantly in the post-processing phase with dynamic reports using a 3D endoscopic view. Specialists in Rhinology have been asked for a more intuitive, simple, powerful CFD software to offer more quality and precision in their work to evaluate the nasal airflow. We present MECOMLAND ® and NOSELAND ® which have all the expected characteristics to fulfil this demand and offer a proper assessment with the maximum of quality plus safety for the patient. These programs represent a non-invasive, low-cost (as the CT scan is already performed in every patient) alternative for the functional study of the difficult rhinologic case. To validate the software, we studied two groups of patients from the Ear Nose Throat clinic, a first group with normal noses and a second group presenting septal deviations. Wall shear stresses are lower in the cases of normal noses in comparison with those for septal deviation. Besides, velocity field distributions, pressure drop between nasopharynx and the ambient, and flow rates in each nostril were different among the nasal cavities in the two groups. These software modules open up a promising future to simulate the nasal airflow behaviour in virtual surgery intervention scenarios under different pressure or

  7. CFD Modeling and Simulation in Materials Processing 2018

    OpenAIRE

    Nastac, Laurentiu; Pericleous, Koulis; Sabau, Adrian S.; Zhang, Lifeng; Thomas, Brian G.

    2018-01-01

    This book contains the proceedings of the symposium “CFD Modeling and Simulation in Materials Processing” held at the TMS 2018 Annual Meeting & Exhibition in Phoenix, Arizona, USA, March 11–15, 2018. This symposium dealt with computational fluid dynamics (CFD) modeling and simulation of engineering processes. The papers published in this book were requested from researchers and engineers involved in the modeling of multiscale and multiphase phenomena in material processing systems. The sympos...

  8. CFD computations of the second round of MEXICO rotor measurements

    DEFF Research Database (Denmark)

    Sørensen, Niels N.; Zahle, Frederik; Boorsma, K.

    2016-01-01

    A comparison, between selected wind tunnel data from the NEW MEXICO measuring campaign and CFD computations are shown. The present work, documents that a state of the art CFD code, including a laminar turbulent transition model, can provide good agreement with experimental data. Good agreement...

  9. A Coupled CFD/FEM Structural Analysis to Determine Deformed Shapes of the RSRM Inhibitors

    Science.gov (United States)

    Dill, Richard A.; Whitesides, R. Harold

    1996-01-01

    Recent trends towards an increase in the stiffness of the acrylonitrile butadiene rubber (NBR) insulation material used in the construction of the redesigned solid rocket motor (RSRM) propellant inhibitors prompted questions about possible effects on RSRM performance. The specific objectives of the computational fluid dynamics (CFD) task included: (1) the definition of pressure loads to calculate the deformed shape of stiffer inhibitors, (2) the calculation of higher port velocities over the inhibitors to determine shifts in the vortex shedding or edge tone frequencies, and (3) the quantification of higher slag impingement and collection rates on the inhibitors and in the submerged nose nozzle cavity.

  10. Comprehensive Forced Response Analysis of J2X Turbine Bladed-Discs with 360 Degree Variation in CFD Loading

    Science.gov (United States)

    Elrod, David; Christensen, Eric; Brown, Andrew

    2011-01-01

    The temporal frequency content of the dynamic pressure predicted by a 360 degree computational fluid dynamics (CFD) analysis of a turbine flow field provides indicators of forcing function excitation frequencies (e.g., multiples of blade pass frequency) for turbine components. For the Pratt and Whitney Rocketdyne J-2X engine turbopumps, Campbell diagrams generated using these forcing function frequencies and the results of NASTRAN modal analyses show a number of components with modes in the engine operating range. As a consequence, forced response and static analyses are required for the prediction of combined stress, high cycle fatigue safety factors (HCFSF). Cyclically symmetric structural models have been used to analyze turbine vane and blade rows, not only in modal analyses, but also in forced response and static analyses. Due to the tortuous flow pattern in the turbine, dynamic pressure loading is not cyclically symmetric. Furthermore, CFD analyses predict dynamic pressure waves caused by adjacent and non-adjacent blade/vane rows upstream and downstream of the row analyzed. A MATLAB script has been written to calculate displacements due to the complex cyclically asymmetric dynamic pressure components predicted by CFD analysis, for all grids in a blade/vane row, at a chosen turbopump running speed. The MATLAB displacements are then read into NASTRAN, and dynamic stresses are calculated, including an adjustment for possible mistuning. In a cyclically symmetric NASTRAN static analysis, static stresses due to centrifugal, thermal, and pressure loading at the mode running speed are calculated. MATLAB is used to generate the HCFSF at each grid in the blade/vane row. When compared to an approach assuming cyclic symmetry in the dynamic flow field, the current approach provides better assurance that the worst case safety factor has been identified. An extended example for a J-2X turbopump component is provided.

  11. Verification of supersonic and hypersonic semi-empirical predictions using CFD

    International Nuclear Information System (INIS)

    McIlwain, S.; Khalid, M.

    2004-01-01

    CFD was used to verify the accuracy of the axial force, normal force, and pitching moment predictions of two semi-empirical codes. This analysis considered the flow around the forebody of four different aerodynamic shapes. These included geometries with equal-volume straight or tapered bodies, with either standard or double-angle nose cones. The flow was tested at freestream Mach numbers of M = 1.5, 4.0, and 7.0. The CFD results gave the expected flow pressure contours for each geometry. The geometries with straight bodies produced larger axial forces, smaller normal forces, and larger pitching moments compared to the geometries with tapered bodies. The double-angle nose cones introduced a shock into the flow, but affected the straight-body geometries more than the tapered-body geometries. Both semi-empirical codes predicted axial forces that were consistent with the CFD data. The agreement between the normal forces and pitching moments was not as good, particularly for the straight-body geometries. But even though the semi-empirical results were not exactly the same as the CFD data, the semi-empirical codes provided rough estimates of the aerodynamic parameters in a fraction of the time required to perform a CFD analysis. (author)

  12. On application of CFD codes to problems of nuclear reactor safety

    International Nuclear Information System (INIS)

    Muehlbauer, Petr

    2005-01-01

    The 'Exploratory Meeting of Experts to Define an Action Plan on the Application of Computational Fluid Dynamics (CFD) Codes to Nuclear Reactor Safety Problems' held in May 2002 at Aix-en-Province, France, recommended formation of writing groups to report the need of guidelines for use and assessment of CFD in single-phase nuclear reactor safety problems, and on recommended extensions to CFD codes to meet the needs of two-phase problems in nuclear reactor safety. This recommendations was supported also by Working Group on the Analysis and Management of Accidents and led to formation oaf three Writing Groups. The first writing Group prepared a summary of existing best practice guidelines for single phase CFD analysis and made a recommendation on the need for nuclear reactor safety specific guidelines. The second Writing Group selected those nuclear reactor safety applications for which understanding requires or is significantly enhanced by single-phase CFD analysis, and proposed a methodology for establishing assesment matrices relevant to nuclear reactor safety applications. The third writing group performed a classification of nuclear reactor safety problems where extension of CFD to two-phase flow may bring real benefit, a classification of different modeling approaches, and specification and analysis of needs in terms of physical and numerical assessments. This presentation provides a review of these activities with the most important conclusions and recommendations (Authors)

  13. Results of a CFD benchmark for wind loads on a high-rise building

    NARCIS (Netherlands)

    Bronkhorst, A.J.; Bentum, C.A. van; Geurts, C.P.W.

    2017-01-01

    In recent years, the use of computational fluid dynamics (CFD) to evaluate flow fields has become more popular in various branches of industry. In building design, there is a similar trend towards the increasing use of CFD. There are several guidelines for CFD analysis of flows in the urban

  14. Calculations of hydrogen transport for the simulation of a Sbo in the NPP-L V using the code CFD GASFLOW

    International Nuclear Information System (INIS)

    Gomez T, A. M.; Xolocostli M, V.; Lopez M, R.; Filio L, C.; Mugica R, C. A.; Royl, P.

    2013-10-01

    The scenario of electric power total loss in the nuclear power plant of Laguna Verde (NPP-L V) has been analyzed using the code MELCOR previously, until reaching fault conditions of the primary container. A mitigation measure to avoid the loss of the primary contention is the realization of a venting toward the secondary contention (reactor building), however this measure bears the potential explosions occurrence risk when the hydrogen accumulated in the primary container with the oxygen of the reactor building atmosphere reacting. In this work a scenario has been supposed that considers the mentioned venting when the pressure of 4.5 kg/cm 2 is reached in the primary container. The information for the hydrogen like an entrance fact is obtained of the MELCOR results and the hydrogen transport in both contentions is analyzed with the code CFD GASFLOW that allows predicting the detailed distribution of the hydrogen volumetric concentration and the possible detonation of flammability conditions in the reactor building. The results show that the venting will produce detonation conditions in the venting level (level 33) and flammability in the level of the recharge floor. The methodology here described constitutes the base of a detailed calculation system of this type of phenomena that can use to make safety evaluations in the NPP-L V on scenarios that include gases transport. (Author)

  15. CFD applications in hypersonic flight

    Science.gov (United States)

    Edwards, T. A.

    1992-01-01

    Design studies are underway for a variety of hypersonic flight vehicles. The National Aero-Space Plane will provide a reusable, single-stage-to-orbit capability for routine access to low earth orbit. Flight-capable satellites will dip into the atmosphere to maneuver to new orbits, while planetary probes will decelerate at their destination by atmospheric aerobraking. To supplement limited experimental capabilities in the hypersonic regime, CFD is being used to analyze the flow about these configurations. The governing equations include fluid dynamic as well as chemical species equations, which are solved with robust upwind differencing schemes. Examples of CFD applications to hypersonic vehicles suggest an important role this technology will play in the development of future aerospace systems. The computational resources needed to obtain solutions are large, but various strategies are being exploited to reduce the time required for complete vehicle simulations.

  16. Examples of using CFD for wind turbine aerodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, M.O.L.; Soerensen, J.N. [Technical Univ. of Denmark, Dept. of Energy Engineering (Denmark); Soerensen, N.N. [Risoe National Lab., Test Station for Wind Turbines (Denmark)

    1997-12-31

    Overall it is concluded that in order to improve the results from CFD (Computational Fluid Dynamics) for wind turbine aerodynamics characterized by: high angles of attack; thick airfoils; 3-D effects; instationary effects. Extreme care must be put on turbulence and transition models, and fine grids are necessary especially at the suction peak. If these precautions are taken CFD can be used as a tool for obtaining lift and drag coefficients for the BEM (Blade Element Momentum) model. (au)

  17. Critical modeling parameters identified for 3D CFD modeling of rectangular final settling tanks for New York City wastewater treatment plants.

    Science.gov (United States)

    Ramalingam, K; Xanthos, S; Gong, M; Fillos, J; Beckmann, K; Deur, A; McCorquodale, J A

    2012-01-01

    New York City Environmental Protection is in the process of incorporating biological nitrogen removal (BNR) in its wastewater treatment plants (WWTPs) which entails operating the aeration tanks with higher levels of mixed liquor suspended solids (MLSS) than a conventional activated sludge process. The objective of this paper is to discuss two of the important parameters introduced in the 3D CFD model that has been developed by the City College of New York (CCNY) group: (a) the development of the 'discrete particle' measurement technique to carry out the fractionation of the solids in the final settling tank (FST) which has critical implications in the prediction of the effluent quality; and (b) the modification of the floc aggregation (K(A)) and floc break-up (K(B)) coefficients that are found in Parker's flocculation equation (Parker et al. 1970, 1971) used in the CFD model. The dependence of these parameters on the predictions of the CFD model will be illustrated with simulation results on one of the FSTs at the 26th Ward WWTP in Brooklyn, NY.

  18. CFD analysis for spacer grid mixing vane design

    International Nuclear Information System (INIS)

    Park, Sung-Kew; Kim, Kang-Hoon; Park, Eung-Jun; Jung, Yil-Sup; Suh, Jung-Min; Jeong, Ji-Hun

    2008-01-01

    A computational fluid dynamics (CFD) analysis for a rod bundle with the larger scale model (6x6 array model) has been performed to develop the base shape of mixing vane in accordance with the hydraulic and thermal performance. Explanatory parameters are span pressure drop and span average heat transfer coefficient. The concern related to hot spot is also considered as a subsidiary criterion. Of the several candidates, the final candidate was determined by using the CFD analysis code, STAR-CD. And then, the optimization for it was performed using the response surface method (RSM) that the proper tolerance was considered under the two acceptance criteria such as lower span pressure drop while maintaining the span average heat transfer coefficient with respect to the current shape. The optimized mixing vane shape was verified by the CFD analysis including the effects of allowable tolerance. (author)

  19. Finite volume thermal-hydraulics and neutronics coupled calculations - 15300

    International Nuclear Information System (INIS)

    Araujo Silva, V.; Campagnole dos Santos, A.A.; Mesquit, A.Z.; Bernal, A.; Miro, R.; Verdu, G.; Pereira, C.

    2015-01-01

    The computational power available nowadays allows the coupling of neutronics and thermal-hydraulics codes for reactor studies. The present methodology foresees at least one constraint to the separated codes in order to perform coupled calculations: both codes must use the same geometry, however, meshes can be different for each code as long as the internal surfaces stays the same. Using the finite volume technique, a 3D diffusion nodal code was implemented to deal with neutron transport. This code can handle non-structured meshes which allows for complicated geometries calculations and therefore more flexibility. A computational fluid dynamics (CFD) code was used in order to obtain the same level of details for the thermal hydraulics calculations. The chosen code is OpenFOAM, an open-source CFD tool. Changes in OpenFOAM allow simple coupled calculations of a PWR fuel rod with neutron transport code. OpenFOAM sends coolant density information and fuel temperature to the neutron transport code that sends back power information. A mapping function is used to average values when one node in one side corresponds to many nodes in the other side. Data is exchanged between codes by library calls. As the results of a fuel rod calculations progress, more complicated and processing demanding geometries will be simulated, aiming to the simulation of a real scale PWR fuel assembly

  20. CFD modeling of fouling in crude oil pre-heaters

    International Nuclear Information System (INIS)

    Bayat, Mahmoud; Aminian, Javad; Bazmi, Mansour; Shahhosseini, Shahrokh; Sharifi, Khashayar

    2012-01-01

    Highlights: ► A conceptual CFD-based model to predict fouling in industrial crude oil pre-heaters. ► Tracing fouling formation in the induction and developing continuation periods. ► Effect of chemical components, shell-side HTC and turbulent flow on the fouling rate. - Abstract: In this study, a conceptual procedure based on the computational fluid dynamic (CFD) technique has been developed to predict fouling rate in an industrial crude oil pre-heater. According to the developed CFD concept crude oil was assumed to be composed of three pseudo-components comprising of petroleum, asphaltene and salt. The binary diffusion coefficients were appropriately categorized into five different groups. The species transport model was applied to simulate the mixing and transport of chemical species. The possibility of adherence of reaction products to the wall was taken into account by applying a high viscosity for the products in competition with the shear stress on the wall. Results showed a reasonable agreement between the model predictions and the plant data. The CFD model could be applied to new operating conditions to investigate the details of the crude oil fouling in the industrial pre-heaters.

  1. Machine and radiation protection challenges of high energy/intensity accelerators: the role of Monte Carlo calculations

    Science.gov (United States)

    Cerutti, F.

    2017-09-01

    The role of Monte Carlo calculations in addressing machine protection and radiation protection challenges regarding accelerator design and operation is discussed, through an overview of different applications and validation examples especially referring to recent LHC measurements.

  2. Using CFD as a Rocket Injector Design Tool: Recent Progress at Marshall Space Flight Center

    Science.gov (United States)

    Tucker, Kevin; West, Jeff; Williams, Robert; Lin, Jeff; Canabal, Francisco; Rocker, marvin; Robles, Bryan; Garcia, Robert; Chenoweth, James

    2005-01-01

    New programs are forcing American propulsion system designers into unfamiliar territory. For instance, industry s answer to the cost and reliability goals set out by the Next Generation Launch Technology Program are engine concepts based on the Oxygen- Rich Staged Combustion Cycle. Historical injector design tools are not well suited for this new task. The empirical correlations do not apply directly to the injector concepts associated with the ORSC cycle. These legacy tools focus primarily on performance with environment evaluation a secondary objective. Additionally, the environmental capability of these tools is usually one-dimensional while the actual environments are at least two- and often three-dimensional. CFD has the potential to calculate performance and multi-dimensional environments but its use in the injector design process has been retarded by long solution turnaround times and insufficient demonstrated accuracy. This paper has documented the parallel paths of program support and technology development currently employed at Marshall Space Flight Center in an effort to move CFD to the forefront of injector design. MSFC has established a long-term goal for use of CFD for combustion devices design. The work on injector design is the heart of that vision and the Combustion Devices CFD Simulation Capability Roadmap that focuses the vision. The SRL concept, combining solution fidelity, robustness and accuracy, has been established as a quantitative gauge of current and desired capability. Three examples of current injector analysis for program support have been presented and discussed. These examples are used to establish the current capability at MSFC for these problems. Shortcomings identified from this experience are being used as inputs to the Roadmap process. The SRL evaluation identified lack of demonstrated solution accuracy as a major issue. Accordingly, the MSFC view of code validation and current MSFC-funded validation efforts were discussed in

  3. Coupled CFD - system-code simulation of a gas cooled reactor

    International Nuclear Information System (INIS)

    Yan, Yizhou; Rizwan-uddin

    2011-01-01

    A generic coupled CFD - system-code thermal hydraulic simulation approach was developed based on FLUENT and RELAP-3D, and applied to LWRs. The flexibility of the coupling methodology enables its application to advanced nuclear energy systems. Gas Turbine - Modular Helium Reactor (GT-MHR) is a Gen IV reactor design which can benefit from this innovative coupled simulation approach. Mixing in the lower plenum of the GT-MHR is investigated here using the CFD - system-code coupled simulation tool. Results of coupled simulations are presented and discussed. The potential of the coupled CFD - system-code approach for next generation of nuclear power plants is demonstrated. (author)

  4. Evaluation of flow accelerated corrosion by coupled analysis of corrosion and flow dynamics (2), flow dynamics calculations for determining mixing factors and mass transfer coefficients

    International Nuclear Information System (INIS)

    Uehara, Yasushi; Uchida, Shunsuke; Naitoh, Masanori; Okada, Hidetoshi; Koshizuka, Seiichi

    2009-01-01

    In order to predict and mitigate flow accelerated corrosion (FAC) of carbon steel piping in PWR and BWR secondary systems, computer program packages for evaluating FAC have been developed by coupling one through three dimensional (1-3D) computational flow dynamics (CFD) models and corrosion models. To evaluate corrosive conditions, e.g., oxygen concentration and electrochemical corrosion potential (ECP) along the flow path, flow pattern and temperature in each elemental volume were obtained with 1D computational flow dynamics (CFD) codes. Precise flow turbulence and mass transfer coefficients at the structure surface were calculated with 3D CFD codes to determine wall thinning rates. One of the engineering options is application of k-ε calculation as a 3D CFD code, which has limitation of detail evaluation of flow distribution at very surface of large scale piping. A combination of k-ε calculation and wall function was proposed to evaluate precise distribution of mass transfer coefficients with reasonable CPU volume and computing time and, at the same time, reasonable accuracy. (author)

  5. Modelling of Air Flow trough a Slatted Floor by CFD

    DEFF Research Database (Denmark)

    Svidt, Kjeld; Bjerg, Bjarne; Morsing, Svend

    In this paper two different CFD-approaches are investigated to model the airflow through a slatted floor. Experiments are carried out in a full-scale test room. The computer simulations are carried out with the CFD-code FLOVENT, which solves the time-averaged Navier-Stokes equations by use of the k...

  6. CFD Simulations of Contaminant Transport between two Breathing Persons

    DEFF Research Database (Denmark)

    Bjørn, Erik; Nielsen, Peter V.

    Experiments have shown that exhalation from one person is able to penetrate the breathing zone of another person at a distance. Computational Fluid Dynamics (CFD) is used to investigate the dependency of the personal exposure on some physical parameters, namely: Pulmonary ventilation rate......, convective heat output, exhalation temperature, and crosssectional exhalation area. Full-scale experimental results are used to calibrate/validate the CFD model....

  7. Load calculation on the nozzle in a flue gas desulphurization system

    Science.gov (United States)

    Róbert, Olšiak; Zoltán, Fuszko; Zoltán, Csuka

    2017-09-01

    The desulphurization system is used to remove sulfur oxides from exhaust, so-called flue gases through absorbing them via the sprayed suspension. The suspension delivered from the pump system to the atmospheric bi-directional double hollow cone nozzle has the prescribed working pressure. The unknown mechanical load on the solid body of the nozzle is present through the change of moment due to the flow of the suspension through the bi-directional outflow areas [1], [4]. The calculation of the acting forces and torques in the 3 directions was carried out with the methods of computational fluid dynamics (CFD) in the software ANSYS Fluent. The geometric model of the flow areas of the nozzle were created with the methods of reverse engineering. The computational mesh required by the CFD solver was created, and its quality verified with the standard criteria. The used boundary conditions were defined by the hydraulic parameters of the pump system, the properties of the suspension present in the hydraulic system were specified by sample analysis. The post-processed and analyzed results of the CFD calculation, the pressure-field and the velocity magnitudes in particular directions were further used as input parameters at the mechanical analysis of the load on the bi-directional nozzle.

  8. CFD Analysis on the Periodic Element of a Printed Circuit Heat Exchanger

    International Nuclear Information System (INIS)

    Tak, Nam-il; Kim, Min-Hwan; Lee, Won-Jae

    2007-01-01

    A typical printed circuit heat exchanger (PCHE) is composed of a large number of flow channels with lateral corrugations. In an effort to investigate fundamental thermo-fluid characteristics of a PCHE with corrugated channels, computational fluid dynamics (CFD) analyses were previously made in. One pair of flow channels (i.e., cold and hot channels) with the entire flow path was considered for the computational domain in the previous studies. Although only one pair of flow channels with coarse meshes was used, computational loads were found to be very high to simulate the entire flow path of the PCHE. Fortunately a recent study has shown that a simplified CFD methodology with a stream wise periodic assumption (called periodic CFD analysis) is feasible for a CFD evaluation of the thermo-fluid performance of compact heat exchangers. Since the periodic CFD analysis focuses on the periodic element of a flow channel, the required computing resources are dramatically reduced. In the present paper, the periodic CFD analysis has been applied to the periodic element of the PCHE. The results are compared with those of the full elements which have an entire flow path. Based on the periodic approach the effects of the corrugation parameters on the thermo-fluid performance of the PCHE are investigated

  9. Possible User-Dependent CFD Predictions of Transitional Flow in Building Ventilation

    DEFF Research Database (Denmark)

    Peng, Lei; Nielsen, Peter Vilhelm; Wang, Xiaoxue

    2016-01-01

    A modified backward-facing step flow with a large expansion ratio of five (5) was modelled by 19 teams without benchmark solutions or experimental data for validation in an ISHVAC-COBEE July 2015 Tianjin Workshop, entitled as “to predict low turbulent flow”. Different computational fluid dynamics...... (CFD) codes/software, turbulence models, boundary conditions, numerical schemes and convergent criteria were adopted based on the own CFD experience of each participating team. The largest coefficient of variation is larger than 50% and the largest relative maximum difference of penetration length......, is shown to be still a very challenging task. This calls for a solid approach of validation and uncertainty assessment in CFD “experiments”. The users are recommended to follow an existing guideline of uncertainty assessment of CFD predictions to minimize the errors and uncertainties in the future....

  10. CFD modeling of a UV-LED photocatalytic odor abatement process in a continuous reactor

    International Nuclear Information System (INIS)

    Wang, Zimeng; Liu, Jing; Dai, Yuancan; Dong, Weiyang; Zhang, Shicheng; Chen, Jianmin

    2012-01-01

    Highlights: ► A CFD model is developed for a UV-LED based photocatalytic deodorization reactor. ► Radiation field model and Langmuir–Hinshelwood kinetics are integrated in the model. ► The model can predict the pollutant concentration profile and the reactor performance. ► LED distance is predicted to be a critical parameter in photocatalytic reactor design. - Abstract: This paper presents a model study of a UV light-emitting-diode (UV-LED) based photocatalytic odor abatement process. It integrated computational fluid dynamics (CFD) modeling of the gas flow in the reactor with LED-array radiation field calculation and Langmuir–Hinshelwood reaction kinetics. It was applied to simulate the photocatalytic degradation of dimethyl sulfide (DMS) in a UV-LED reactor based on experimentally determined chemical kinetic parameters. A non-linear power law relating reaction rate to irradiation intensity was adopted. The model could predict the steady state DMS concentration profiles by calculating the advection, diffusion and Langmuir–Hinshelwood reaction kinetics. By affecting the radiation intensity and uniformity, the position of the LED array relative to the catalyst appeared to be a critical parameter determining DMS removal efficiency. Too small distances might yield low quantum efficiency and consequently poor abatement performance. This study provided an example of LED-based photocatalytic process modeling and gave insights into the optimization of light source design for photocatalytic applications.

  11. Experimental investigation and CFD simulation of horizontal stratified two-phase flow phenomena

    International Nuclear Information System (INIS)

    Vallee, Christophe; Hoehne, Thomas; Prasser, Horst-Michael; Suehnel, Tobias

    2008-01-01

    For the investigation of stratified two-phase flow, two horizontal channels with rectangular cross-section were built at Forschungszentrum Dresden-Rossendorf (FZD). The channels allow the investigation of air/water co-current flows, especially the slug behaviour, at atmospheric pressure and room temperature. The test-sections are made of acrylic glass, so that optical techniques, like high-speed video observation or particle image velocimetry (PIV), can be applied for measurements. The rectangular cross-section was chosen to provide better observation possibilities. Moreover, dynamic pressure measurements were performed and synchronised with the high-speed camera system. CFD post-test simulations of stratified flows were performed using the code ANSYS CFX. The Euler-Euler two fluid model with the free surface option was applied on grids of minimum 4 x 10 5 control volumes. The turbulence was modelled separately for each phase using the k-ω-based shear stress transport (SST) turbulence model. The results compare very well in terms of slug formation, velocity, and breaking. The qualitative agreement between calculation and experiment is encouraging and shows that CFD can be a useful tool in studying horizontal two-phase flow

  12. Experimental investigation and CFD simulation of horizontal stratified two-phase flow phenomena

    International Nuclear Information System (INIS)

    Vallee, Christophe; Hohne, Thomas; Prasser, Horst-Michael; Suhnel, Tobias

    2007-01-01

    For the investigation of stratified two-phase flow, two horizontal channels with rectangular cross-section were built at Forschungszentrum Rossendorf. The channels allow the investigation of air/water co-current flows, especially the slug behaviour, at atmospheric pressure and room temperature. The test-sections are made of acrylic glass, so that optical techniques, like high-speed video observation or particle image velocimetry (PIV), can be applied for measurements. The rectangular cross-section was chosen to provide better observation possibilities. Moreover, dynamic pressure measurements were performed and synchronized with the high-speed camera system. CFD post test simulations of stratified flows were performed using the code ANSYS CFX. The Euler- Euler two fluid model with the free surface option was applied on grids of minimum 4.10 5 control volumes. The turbulence was modelled separately for each phase using the k-ω based shear stress transport (SST) turbulence model. The results compare very well in terms of slug formation, velocity, and breaking. The qualitative agreement between calculation and experiment is encouraging and shows that CFD can be a useful tool in studying horizontal two-phase flow. (authors)

  13. Experimental investigation and CFD simulation of horizontal stratified two-phase flow phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Vallee, Christophe [Forschungszentrum Dresden-Rossendorf e.V., Dresden (Germany)], E-mail: c.vallee@fzd.de; Hoehne, Thomas; Prasser, Horst-Michael; Suehnel, Tobias [Forschungszentrum Dresden-Rossendorf e.V., Dresden (Germany)

    2008-03-15

    For the investigation of stratified two-phase flow, two horizontal channels with rectangular cross-section were built at Forschungszentrum Dresden-Rossendorf (FZD). The channels allow the investigation of air/water co-current flows, especially the slug behaviour, at atmospheric pressure and room temperature. The test-sections are made of acrylic glass, so that optical techniques, like high-speed video observation or particle image velocimetry (PIV), can be applied for measurements. The rectangular cross-section was chosen to provide better observation possibilities. Moreover, dynamic pressure measurements were performed and synchronised with the high-speed camera system. CFD post-test simulations of stratified flows were performed using the code ANSYS CFX. The Euler-Euler two fluid model with the free surface option was applied on grids of minimum 4 x 10{sup 5} control volumes. The turbulence was modelled separately for each phase using the k-{omega}-based shear stress transport (SST) turbulence model. The results compare very well in terms of slug formation, velocity, and breaking. The qualitative agreement between calculation and experiment is encouraging and shows that CFD can be a useful tool in studying horizontal two-phase flow.

  14. PIV Uncertainty Methodologies for CFD Code Validation at the MIR Facility

    Energy Technology Data Exchange (ETDEWEB)

    Sabharwall, Piyush [Idaho National Lab. (INL), Idaho Falls, ID (United States); Skifton, Richard [Idaho National Lab. (INL), Idaho Falls, ID (United States); Stoots, Carl [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kim, Eung Soo [Idaho National Lab. (INL), Idaho Falls, ID (United States); Conder, Thomas [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2013-12-01

    Currently, computational fluid dynamics (CFD) is widely used in the nuclear thermal hydraulics field for design and safety analyses. To validate CFD codes, high quality multi dimensional flow field data are essential. The Matched Index of Refraction (MIR) Flow Facility at Idaho National Laboratory has a unique capability to contribute to the development of validated CFD codes through the use of Particle Image Velocimetry (PIV). The significance of the MIR facility is that it permits non intrusive velocity measurement techniques, such as PIV, through complex models without requiring probes and other instrumentation that disturb the flow. At the heart of any PIV calculation is the cross-correlation, which is used to estimate the displacement of particles in some small part of the image over the time span between two images. This image displacement is indicated by the location of the largest peak. In the MIR facility, uncertainty quantification is a challenging task due to the use of optical measurement techniques. Currently, this study is developing a reliable method to analyze uncertainty and sensitivity of the measured data and develop a computer code to automatically analyze the uncertainty/sensitivity of the measured data. The main objective of this study is to develop a well established uncertainty quantification method for the MIR Flow Facility, which consists of many complicated uncertainty factors. In this study, the uncertainty sources are resolved in depth by categorizing them into uncertainties from the MIR flow loop and PIV system (including particle motion, image distortion, and data processing). Then, each uncertainty source is mathematically modeled or adequately defined. Finally, this study will provide a method and procedure to quantify the experimental uncertainty in the MIR Flow Facility with sample test results.

  15. CFD analysis of liquid metal cooled rod assembly

    Energy Technology Data Exchange (ETDEWEB)

    Son, H.M.; Suh, K.Y. [Seoul National Univ. (Korea, Republic of)

    2007-07-01

    The model subassembly of the BREST-type reactor core is a pin bundle of square arrangement. In this bundle there are two zones which differ with respect to pin diameters and level of heat production. The model pin bundle contains one spacer grid which is located near the midplane of the rod bundle geometry. The coolant consists of a eutectic alloy of 22% sodium (Na) plus 78% potassium (K). Experiments were performed in order to observe the thermal hydraulic behavior of the liquid metal coolant in the BREST core simulator. Results were obtained for the coolant exit temperatures, central measuring pin simulator external surface temperatures, and coolant velocities at the perimeter of the measuring pin simulator. A computational fluid dynamics (CFD) code is used to simulate the liquid metal flows in subchannels. Semi-fine mesh structures were used to model the flow with reasonable accuracy and speed once rigorous node resolution dependency had been tested. A subchannel analysis code was used to investigate the flows as well. Since the subchannel analysis code is based on a lumped parameter model, it only calculates the subchannel averaged velocity values. The CFD code results were averaged on the subchannel basis to be comparable with the results from the subchannel code. The mixing vane is not considered for the time being so as to simplify the problem and to reduce the computational cost. The two codes showed similar results. The difference between the experimental and computational results is considered to mainly originate from the existence of the mixing vane. (authors)

  16. CFD analysis of liquid metal cooled rod assembly

    International Nuclear Information System (INIS)

    Son, H.M.; Suh, K.Y.

    2007-01-01

    The model subassembly of the BREST-type reactor core is a pin bundle of square arrangement. In this bundle there are two zones which differ with respect to pin diameters and level of heat production. The model pin bundle contains one spacer grid which is located near the midplane of the rod bundle geometry. The coolant consists of a eutectic alloy of 22% sodium (Na) plus 78% potassium (K). Experiments were performed in order to observe the thermal hydraulic behavior of the liquid metal coolant in the BREST core simulator. Results were obtained for the coolant exit temperatures, central measuring pin simulator external surface temperatures, and coolant velocities at the perimeter of the measuring pin simulator. A computational fluid dynamics (CFD) code is used to simulate the liquid metal flows in subchannels. Semi-fine mesh structures were used to model the flow with reasonable accuracy and speed once rigorous node resolution dependency had been tested. A subchannel analysis code was used to investigate the flows as well. Since the subchannel analysis code is based on a lumped parameter model, it only calculates the subchannel averaged velocity values. The CFD code results were averaged on the subchannel basis to be comparable with the results from the subchannel code. The mixing vane is not considered for the time being so as to simplify the problem and to reduce the computational cost. The two codes showed similar results. The difference between the experimental and computational results is considered to mainly originate from the existence of the mixing vane. (authors)

  17. Comparison of CFD Predictions with Shuttle Global Flight Thermal Imagery and Discrete Surface Measurements

    Science.gov (United States)

    Wood, William A.; Kleb, William L.; Tang, chun Y.; Palmer, Grant E.; Hyatt, Andrew J.; Wise, Adam J.; McCloud, Peter L.

    2010-01-01

    Surface temperature measurements from the STS-119 boundary-layer transition experiment on the space shuttle orbiter Discovery provide a rare opportunity to assess turbulent CFD models at hypersonic flight conditions. This flight data was acquired by on-board thermocouples and by infrared images taken off-board by the Hypersonic Thermodynamic Infrared Measurements (HYTHIRM) team, and is suitable for hypersonic CFD turbulence assessment between Mach 6 and 14. The primary assessment is for the Baldwin-Lomax and Cebeci-Smith algebraic turbulence models in the DPLR and LAURA CFD codes, respectively. A secondary assessment is made of the Shear-Stress Transport (SST) two-equation turbulence model in the DPLR code. Based upon surface temperature comparisons at eleven thermocouple locations, the algebraic-model turbulent CFD results average 4% lower than the measurements for Mach numbers less than 11. For Mach numbers greater than 11, the algebraic-model turbulent CFD results average 5% higher than the three available thermocouple measurements. Surface temperature predictions from the two SST cases were consistently 3 4% higher than the algebraic-model results. The thermocouple temperatures exhibit a change in trend with Mach number at about Mach 11; this trend is not reflected in the CFD results. Because the temperature trends from the turbulent CFD simulations and the flight data diverge above Mach 11, extrapolation of the turbulent CFD accuracy to higher Mach numbers is not recommended.

  18. Development, use, and validation of the CFD tool FLACS for hydrogen safety studies

    Energy Technology Data Exchange (ETDEWEB)

    Middha, Prankul

    2010-07-01

    Computational Fluid Dynamics (CFD) calculations for gas explosion safety have been widely used for doing risk assessments within the oil and gas industry for more than a decade. Based on predicted consequences of a range of potential accident scenarios a risk level is predicted. The development of applications using hydrogen as a clean energy carrier has accelerated in recent years, and hydrogen may be used widely in future. Due to the very high reactivity of hydrogen, safe handling is critical. To be able to perform proper consequence modeling as a part of a risk assessment, it is essential to be able to model the physical processes well. CFD tools have the potential to model the relevant physics and predict well, but without proper user guidelines based on extensive validation work, very mixed prediction capability can be expected. This paper deals with the development and validation of the CFD tool FLACS for hydrogen safety applications. Significant validation work against several experiments has been carried out in order to increase the confidence of predictions of scenarios relevant to hydrogen safety. The validation studies have included dispersion, explosion and combined dispersion and explosion studies. A range of different dispersion experiments is simulated, including low momentum releases in a garage, sub-sonic jets in a garage with stratification effects and subsequent slow diffusion, low momentum and subsonic horizontal jets influenced by buoyancy, and free jets from high-pressure vessels. LH2 releases are also considered. Some of the simulations are performed as blind predictions. FLACS uses a utility program in order to model releases from high-pressure reservoirs. Work has been carried out in order to extend the models in the utility program in order to include real gas effects. Validation against explosion experiments in geometries ranging from smooth and obstructed pipes, refueling station, tunnel, vented vessels, jet-ignited lane, etc. have been

  19. Machine and radiation protection challenges of high energy/intensity accelerators: the role of Monte Carlo calculations

    Directory of Open Access Journals (Sweden)

    Cerutti F.

    2017-01-01

    Full Text Available The role of Monte Carlo calculations in addressing machine protection and radiation protection challenges regarding accelerator design and operation is discussed, through an overview of different applications and validation examples especially referring to recent LHC measurements.

  20. A CFD model for analysis of performance, water and thermal distribution, and mechanical related failure in PEM fuel cells

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi

    2016-07-01

    Full Text Available This paper presents a comprehensive three–dimensional, multi–phase, non-isothermal model of a Proton Exchange Membrane (PEM fuel cell that incorporates significant physical processes and key parameters affecting the fuel cell performance. The model construction involves equations derivation, boundary conditions setting, and solution algorithm flow chart. Equations in gas flow channels, gas diffusion layers (GDLs, catalyst layers (CLs, and membrane as well as equations governing cell potential and hygro-thermal stresses are described. The algorithm flow chart starts from input of the desired cell current density, initialization, iteration of the equations solution, and finalizations by calculating the cell potential. In order to analyze performance, water and thermal distribution, and mechanical related failure in the cell, the equations are solved using a computational fluid dynamic (CFD code. Performance analysis includes a performance curve which plots the cell potential (Volt against nominal current density (A/cm2 as well as losses. Velocity vectors of gas and liquid water, liquid water saturation, and water content profile are calculated. Thermal distribution is then calculated together with hygro-thermal stresses and deformation. The CFD model was executed under boundary conditions of 20°C room temperature, 35% relative humidity, and 1 MPA pressure on the lower surface. Parameters values of membrane electrode assembly (MEA and other base conditions are selected. A cell with dimension of 1 mm x 1 mm x 50 mm is used as the object of analysis. The nominal current density of 1.4 A/cm2 is given as the input of the CFD calculation. The results show that the model represents well the performance curve obtained through experiment. Moreover, it can be concluded that the model can help in understanding complex process in the cell which is hard to be studied experimentally, and also provides computer aided tool for design and optimization of PEM

  1. Practical application of a commercial CFD package in a design/build environment

    Energy Technology Data Exchange (ETDEWEB)

    Berkoe, J; Krag, P; Rayner, C; Imrie, W [Bechtel Corp., San Francisco, CA (United States)

    1996-08-01

    Some examples of how computational fluid dynamics (CFD) has been used to solve problems in the design of metallurgical plants, were presented. CFD has been used to optimize equipment for several unit operations at Bechtel Mining and Metals, and also in developing technologies to improve environmental conditions in several facilities. Some examples included mixing in a copper refining furnace, flow in copper solvent extraction settlers, the ventilation of electrowinning tank houses, and the capture of fugitive emissions from Peirce-Smith converters. Cost effective use of CFD on such projects requires substantial investment in high-end computing equipment, versatile commercial CFD software and advanced data visualization, however, in the hands of a sophisticated analyst the results are well worth the expense. 21 refs., 2 tabs., 7 figs.

  2. CFD Vision 2030 Study: A Path to Revolutionary Computational Aerosciences

    Science.gov (United States)

    Slotnick, Jeffrey; Khodadoust, Abdollah; Alonso, Juan; Darmofal, David; Gropp, William; Lurie, Elizabeth; Mavriplis, Dimitri

    2014-01-01

    This report documents the results of a study to address the long range, strategic planning required by NASA's Revolutionary Computational Aerosciences (RCA) program in the area of computational fluid dynamics (CFD), including future software and hardware requirements for High Performance Computing (HPC). Specifically, the "Vision 2030" CFD study is to provide a knowledge-based forecast of the future computational capabilities required for turbulent, transitional, and reacting flow simulations across a broad Mach number regime, and to lay the foundation for the development of a future framework and/or environment where physics-based, accurate predictions of complex turbulent flows, including flow separation, can be accomplished routinely and efficiently in cooperation with other physics-based simulations to enable multi-physics analysis and design. Specific technical requirements from the aerospace industrial and scientific communities were obtained to determine critical capability gaps, anticipated technical challenges, and impediments to achieving the target CFD capability in 2030. A preliminary development plan and roadmap were created to help focus investments in technology development to help achieve the CFD vision in 2030.

  3. PIV-measured versus CFD-predicted flow dynamics in anatomically realistic cerebral aneurysm models.

    Science.gov (United States)

    Ford, Matthew D; Nikolov, Hristo N; Milner, Jaques S; Lownie, Stephen P; Demont, Edwin M; Kalata, Wojciech; Loth, Francis; Holdsworth, David W; Steinman, David A

    2008-04-01

    Computational fluid dynamics (CFD) modeling of nominally patient-specific cerebral aneurysms is increasingly being used as a research tool to further understand the development, prognosis, and treatment of brain aneurysms. We have previously developed virtual angiography to indirectly validate CFD-predicted gross flow dynamics against the routinely acquired digital subtraction angiograms. Toward a more direct validation, here we compare detailed, CFD-predicted velocity fields against those measured using particle imaging velocimetry (PIV). Two anatomically realistic flow-through phantoms, one a giant internal carotid artery (ICA) aneurysm and the other a basilar artery (BA) tip aneurysm, were constructed of a clear silicone elastomer. The phantoms were placed within a computer-controlled flow loop, programed with representative flow rate waveforms. PIV images were collected on several anterior-posterior (AP) and lateral (LAT) planes. CFD simulations were then carried out using a well-validated, in-house solver, based on micro-CT reconstructions of the geometries of the flow-through phantoms and inlet/outlet boundary conditions derived from flow rates measured during the PIV experiments. PIV and CFD results from the central AP plane of the ICA aneurysm showed a large stable vortex throughout the cardiac cycle. Complex vortex dynamics, captured by PIV and CFD, persisted throughout the cardiac cycle on the central LAT plane. Velocity vector fields showed good overall agreement. For the BA, aneurysm agreement was more compelling, with both PIV and CFD similarly resolving the dynamics of counter-rotating vortices on both AP and LAT planes. Despite the imposition of periodic flow boundary conditions for the CFD simulations, cycle-to-cycle fluctuations were evident in the BA aneurysm simulations, which agreed well, in terms of both amplitudes and spatial distributions, with cycle-to-cycle fluctuations measured by PIV in the same geometry. The overall good agreement

  4. CFD simulations of a turbulent flow in a T-junction

    Energy Technology Data Exchange (ETDEWEB)

    Morii, T. [Japan Nuclear Energy Safety Organization, Toranomon, Tokyo (Japan); Onishi, Y.; Hirakawa, K.; Nakamori, I. [AdvanceSoft Akasaka, Tokyo (Japan)

    2011-07-01

    Very careful T-junction tests are being performed at the Vattenfall Alkarleby Laboratory. Data from a recent test were used as the basis of an OECD/NEA blind benchmark exercise. JNES participated in this blind benchmark exercise. The present T-junction CFD simulation was performed as an incompressible fluid flow and buoyant effect was estimated by using the Boussinesq approximation. Four hexahedral grids (0.25M, 1M, 4M and 16M) were generated for grid size sensitivity study. The Large Eddy Simulation (LES) and the Reynolds Averaged Navier Stokes (RANS) turbulent models were used for a model sensitivity study. All calculation results of LES were closer to the experimental data than those of RANS. (author)

  5. An introduction to chaos theory in CFD

    Science.gov (United States)

    Pulliam, Thomas H.

    1990-01-01

    The popular subject 'chaos theory' has captured the imagination of a wide variety of scientists and engineers. CFD has always been faced with nonlinear systems and it is natural to assume that nonlinear dynamics will play a role at sometime in such work. This paper will attempt to introduce some of the concepts and analysis procedures associated with nonlinear dynamics theory. In particular, results from computations of an airfoil at high angle of attack which exhibits a sequence of bifurcations for single frequency unsteady shedding through period doublings cascading into low dimensional chaos are used to present and demonstrate various aspects of nonlinear dynamics in CFD.

  6. Coarse-grid-CFD. An advantageous alternative to subchannel analysis

    International Nuclear Information System (INIS)

    Class, A.G.; Himmel, S.R.; Viellieber, M.O.

    2011-01-01

    In the 1960 th to 80 th when current GEN II reactor technology was developed, the only possible approach was to use one-dimensional subchannel analysis to compute the flow inside a fuel bundle so that the subchannel scale could be resolved. For simulations of the whole reactor core either system codes or homogenization were employed. In system codes resolution of individual assemblies was the state of the art. Homogenization used porous media equations simulations and averaged the thermohydraulics on reactor core scale. Current potent computing power allows using Computational Fluid Dynamics (CFD) to simulate individual fuel assemblies. Yet the large number of fuel assemblies within the core forbids exploiting CFD for core wide simulation. We propose to combine ideas of subchannel analysis and CFD to develop a new methodology which takes advantage of the fast development of commercial CFD software and the efficiency of subchannel analysis. In this methodology was first applied to simulate a wire-wrap fuel bundle of the High Performance Light Water Reactor (HPLWR). Computations using an inviscid Euler solver on an extremely coarse grid were tuned to predict the true thermohydraulics by adding volumetric forces. These forces represent the non-resolved sub-grid physics. The volumetric forces cannot be measured directly. However, they can be accessed from detailed CFD simulations resolving all relevant physics. Parameterization of these subgrid forces can be realized analogous to models in subchannel codes. In the present work we extend the methodology to the open source solver OpenFOAM and a specific hexagonal fuel assembly which is studied in the framework of liquid metal cooled GEN IV reactor concepts. (orig.)

  7. CFD simulation of air to air enthalpy heat exchanger

    International Nuclear Information System (INIS)

    Al-Waked, Rafat; Nasif, Mohammad Shakir; Morrison, Graham; Behnia, Masud

    2013-01-01

    Highlights: • A CFD model capable of modelling conjugate heat and mass transfer processes. • A mesh independence studies and a CFD model validation have been conducted. • Effects of flow direction on the effectiveness have been examined. • Performance parameters were sensible and latent effectiveness and pressure drop. - Abstract: A CFD model which supports conjugate heat and mass transfer problem representation across the membrane of air-to-air energy recovery heat exchangers has been developed. The model consists of one flow passage for the hot stream and another for the adjacent cold stream. Only half of each flow passage volume has been modelled on each side of the membrane surface. Three dimensional, steady state and laminar flow studies have been conducted using a commercial CFD package. The volumetric species transport model has been adopted to describe the H 2 O and air gas mixtures. Mesh dependency has been examined and followed by validation of the CFD model against published data. Furthermore, effects of flow direction at the inlet of the heat exchanger on its thermal effectiveness have been investigated. Simulation results are presented and analysed in terms of sensible effectiveness, latent effectiveness and pressure drop across the membrane heat exchanger. Results have shown that counter-flow configuration has greater sensitivity to the mesh centre perpendicular distance from the membrane when compared to the other two flow configurations (cross-/parallel-flow). However, the lateral mesh element length has shown minimal effect on the thermal effectiveness of the enthalpy heat exchanger. For the quasi-flow heat exchanger, a perpendicular flow direction to the inlets has been found to produce a higher performance in contrast to the non-perpendicular flow

  8. High performance shape annealing matrix (HPSAM) methodology for core protection calculators

    International Nuclear Information System (INIS)

    Cha, K. H.; Kim, Y. H.; Lee, K. H.

    1999-01-01

    In CPC(Core Protection Calculator) of CE-type nuclear power plants, the core axial power distribution is calculated to evaluate the safety-related parameters. The accuracy of the CPC axial power distribution highly depends on the quality of the so called shape annealing matrix(SAM). Currently, SAM is determined by using data measured during startup test and used throughout the entire cycle. An issue concerned with SAM is that it is fairly sensitive to measurements and thus the fidelity of SAM is not guaranteed for all cycles. In this paper, a novel method to determine a high-performance SAM (HPSAM) is proposed, where both measured and simulated data are used in determining SAM

  9. Application of Computational Fluid Dynamics (CFD) in transonic wind-tunnel/flight-test correlation

    Science.gov (United States)

    Murman, E. M.

    1982-01-01

    The capability for calculating transonic flows for realistic configurations and conditions is discussed. Various phenomena which were modeled are shown to have the same order of magnitude on the influence of predicted results. It is concluded that CFD can make the following contributions to the task of correlating wind tunnel and flight test data: some effects of geometry differences and aeroelastic distortion can be predicted; tunnel wall effects can be assessed and corrected for; and the effects of model support systems and free stream nonuniformities can be modeled.

  10. Development and acceleration of unstructured mesh-based cfd solver

    Science.gov (United States)

    Emelyanov, V.; Karpenko, A.; Volkov, K.

    2017-06-01

    The study was undertaken as part of a larger effort to establish a common computational fluid dynamics (CFD) code for simulation of internal and external flows and involves some basic validation studies. The governing equations are solved with ¦nite volume code on unstructured meshes. The computational procedure involves reconstruction of the solution in each control volume and extrapolation of the unknowns to find the flow variables on the faces of control volume, solution of Riemann problem for each face of the control volume, and evolution of the time step. The nonlinear CFD solver works in an explicit time-marching fashion, based on a three-step Runge-Kutta stepping procedure. Convergence to a steady state is accelerated by the use of geometric technique and by the application of Jacobi preconditioning for high-speed flows, with a separate low Mach number preconditioning method for use with low-speed flows. The CFD code is implemented on graphics processing units (GPUs). Speedup of solution on GPUs with respect to solution on central processing units (CPU) is compared with the use of different meshes and different methods of distribution of input data into blocks. The results obtained provide promising perspective for designing a GPU-based software framework for applications in CFD.

  11. CFD simulation of crossflow mixing in a rod bundle with mixing blades

    International Nuclear Information System (INIS)

    In, W. K.

    1999-01-01

    A CFD model was developed in this study to simulate the crossflow mixing in a 4x4 square array rod bundle caused by ripped-open blades. The central subchannel and adjacent subchannels of one grid span were modeled using flow symmetry. The lateral velocity pattern within the central subchannel, lateral velocity and the turbulence intensity in the rod gap region were predicted by the CFD method, and the predictions were compared with the measurements. The CFD simulation shows a vortex flow around the fuel rod caused by a pair of blades, which is consistent with the experimental results. The CFD predictions of the lateral velocity on the mixing sections show a near symmetric profile, but the measurements present an asymmetric velocity profile leading to an inversion of lateral velocity. The predicted mixing rate between the central subchannel and the adjacent subchannels reasonably agrees with the measured one. The CFD prediction shows a parabolic distribution of the RMS velocity but the measured one shows a rather flat distribution near the blade that develops to a parabolic distribution far downstream (L=29De). The predicted average RMS velocity on a mixing section is also slightly lower than the measured one. This study confirmed that the CFD simulation can present the effect of the ripped-open blades on the crossflow mixing in a rod bundle well

  12. Numerical CFD Simulation and Test Correlation in a Flight Project Environment

    Science.gov (United States)

    Gupta, K. K.; Lung, S. F.; Ibrahim, A. H.

    2015-01-01

    This paper presents detailed description of a novel CFD procedure and comparison of its solution results to that obtained by other available CFD codes as well as actual flight and wind tunnel test data pertaining to the GIII aircraft, currently undergoing flight testing at AFRC.

  13. Study of tip loss corrections using CFD rotor computations

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Zhu, Wei Jun; Sørensen, Jens Nørkær

    2014-01-01

    Tip loss correction is known to play an important role for engineering prediction of wind turbine performance. There are two different types of tip loss corrections: tip corrections on momentum theory and tip corrections on airfoil data. In this paper, we study the latter using detailed CFD...... computations for wind turbines with sharp tip. Using the technique of determination of angle of attack and the CFD results for a NordTank 500 kW rotor, airfoil data are extracted and a new tip loss function on airfoil data is derived. To validate, BEM computations with the new tip loss function are carried out...... and compared with CFD results for the NordTank 500 kW turbine and the NREL 5 MW turbine. Comparisons show that BEM with the new tip loss function can predict correctly the loading near the blade tip....

  14. OpenFOAM: Open source CFD in research and industry

    Science.gov (United States)

    Jasak, Hrvoje

    2009-12-01

    The current focus of development in industrial Computational Fluid Dynamics (CFD) is integration of CFD into Computer-Aided product development, geometrical optimisation, robust design and similar. On the other hand, in CFD research aims to extend the boundaries ofpractical engineering use in "non-traditional " areas. Requirements of computational flexibility and code integration are contradictory: a change of coding paradigm, with object orientation, library components, equation mimicking is proposed as a way forward. This paper describes OpenFOAM, a C++ object oriented library for Computational Continuum Mechanics (CCM) developed by the author. Efficient and flexible implementation of complex physical models is achieved by mimicking the form ofpartial differential equation in software, with code functionality provided in library form. Open Source deployment and development model allows the user to achieve desired versatility in physical modeling without the sacrifice of complex geometry support and execution efficiency.

  15. CFD Modeling in Development of Renewable Energy Applications

    OpenAIRE

    Maher A.R. Sadiq Al-Baghdadi

    2013-01-01

    Chapter 1: A Multi-fluid Model to Simulate Heat and Mass Transfer in a PEM Fuel Cell. Torsten Berning, Madeleine Odgaard, Søren K. Kær Chapter 2: CFD Modeling of a Planar Solid Oxide Fuel Cell (SOFC) for Clean Power Generation. Meng Ni Chapter 3: Hydrodynamics and Hydropower in the New Paradigm for a Sustainable Engineering. Helena M. Ramos, Petra A. López-Jiménez Chapter 4: Opportunities for CFD in Ejector Solar Cooling. M. Dennis Chapter 5: Three Dimensional Modelling of Flow Field Around a...

  16. CFD optimization of a pellet burner

    Directory of Open Access Journals (Sweden)

    Westerlund Lars B.

    2012-01-01

    Full Text Available Increased capacity of computers has made CFD technology attractive for the design of different apparatuses. Optimization of a pellet burner using CFD was investigated in this paper. To make the design tool work fast, an approach with only mixing of gases was simulated. Other important phenomena such as chemical reactions were omitted in order to speed up the design process. The original design of the burner gave unsatisfactory performance. The optimized design achieved from simulation was validated and the results show a significant improvement. The power output increased and the emission of unburned species decreased but could be further reduced. The contact time between combustion gases and secondary air was probably too short. An increased contact time in high temperature conditions would possibly improve the design further.

  17. Thermal Protection System Cavity Heating for Simplified and Actual Geometries Using Computational Fluid Dynamics Simulations with Unstructured Grids

    Science.gov (United States)

    McCloud, Peter L.

    2010-01-01

    Thermal Protection System (TPS) Cavity Heating is predicted using Computational Fluid Dynamics (CFD) on unstructured grids for both simplified cavities and actual cavity geometries. Validation was performed using comparisons to wind tunnel experimental results and CFD predictions using structured grids. Full-scale predictions were made for simplified and actual geometry configurations on the Space Shuttle Orbiter in a mission support timeframe.

  18. CFD Models of a Serpentine Inlet, Fan, and Nozzle

    Science.gov (United States)

    Chima, R. V.; Arend, D. J.; Castner, R. S.; Slater, J. W.; Truax, P. P.

    2010-01-01

    Several computational fluid dynamics (CFD) codes were used to analyze the Versatile Integrated Inlet Propulsion Aerodynamics Rig (VIIPAR) located at NASA Glenn Research Center. The rig consists of a serpentine inlet, a rake assembly, inlet guide vanes, a 12-in. diameter tip-turbine driven fan stage, exit rakes or probes, and an exhaust nozzle with a translating centerbody. The analyses were done to develop computational capabilities for modeling inlet/fan interaction and to help interpret experimental data. Three-dimensional Reynolds averaged Navier-Stokes (RANS) calculations of the fan stage were used to predict the operating line of the stage, the effects of leakage from the turbine stream, and the effects of inlet guide vane (IGV) setting angle. Coupled axisymmetric calculations of a bellmouth, fan, and nozzle were used to develop techniques for coupling codes together and to investigate possible effects of the nozzle on the fan. RANS calculations of the serpentine inlet were coupled to Euler calculations of the fan to investigate the complete inlet/fan system. Computed wall static pressures along the inlet centerline agreed reasonably well with experimental data but computed total pressures at the aerodynamic interface plane (AIP) showed significant differences from the data. Inlet distortion was shown to reduce the fan corrected flow and pressure ratio, and was not completely eliminated by passage through the fan

  19. Validation of a CFD model simulating charge and discharge of a small heat storage test module based on a sodium acetate water mixture

    DEFF Research Database (Denmark)

    Dannemand, Mark; Fan, Jianhua; Furbo, Simon

    2014-01-01

    Experimental and theoretical investigations are carried out to study the heating of a 302 x 302 x 55 mm test box of steel containing a sodium acetate water mixture. A thermostatic bath has been set up to control the charging and discharging of the steel box. The charging and discharging has been...... for a Computational Fluid Dynamics (CFD) model. The CFD calculated temperatures are compared to measured temperatures internally in the box to validate the CFD model. Four cases are investigated; heating the test module with the sodium acetate water mixture in solid phase from ambient temperature to 52˚C; heating...... the module starting with the salt water mixture in liquid phase from 72˚C to 95˚C; heating up the module from ambient temperature with the salt water mixture in solid phase, going through melting, ending in liquid phase at 78˚C/82˚C; and discharging the test module from liquid phase at 82˚C, going through...

  20. CFD investigating the effects of different operating conditions on the performance and the characteristics of a high-temperature PEMFC

    International Nuclear Information System (INIS)

    Su, A.; Ferng, Y.M.; Shih, J.C.

    2010-01-01

    The effects of different operating conditions on the performance and the characteristics of a high-temperature proton exchange membrane fuel cell (PEMFC) are investigated using a three-dimensional (3-D) computational fluid dynamics (CFD) fuel-cell model. This model consists of the thermal-hydraulic equations and the electrochemical equations. Different operating conditions studied in this paper include the inlet gas temperature, system pressure, and inlet gas flow rate, respectively. Corresponding experiments are also carried out to assess the accuracy of this CFD model. Under the different operating conditions, the PEMFC performance curves predicted by the model correspond well with the experimentally measured ones. The performance of PEMFC is improved as the increase in the inlet temperature, system pressure or flow rate, which is precisely captured by the CFD fuel cell model. In addition, the concentration polarization caused by the insufficient supply of fuel gas can be also simulated as the high-temperature PEMFC is operated at the higher current density. Based on the calculation results, the localized thermal-hydraulic characteristics within a PEMFC can be reasonably captured. These characteristics include the fuel gas distribution, temperature variation, liquid water saturation distribution, and membrane conductivity, etc.

  1. COMPARISON OF EXPERIMENTS TO CFD MODELS FOR MIXING USING DUAL OPPOSING JETS IN TANKS WITH AND WITHOUT INTERNAL OBSTRUCTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Leishear, R.; Poirier, M.; Lee, S.; Fowley, M.

    2012-06-26

    This paper documents testing methods, statistical data analysis, and a comparison of experimental results to CFD models for blending of fluids, which were blended using a single pump designed with dual opposing nozzles in an eight foot diameter tank. Overall, this research presents new findings in the field of mixing research. Specifically, blending processes were clearly shown to have random, chaotic effects, where possible causal factors such as turbulence, pump fluctuations, and eddies required future evaluation. CFD models were shown to provide reasonable estimates for the average blending times, but large variations -- or scatter -- occurred for blending times during similar tests. Using this experimental blending time data, the chaotic nature of blending was demonstrated and the variability of blending times with respect to average blending times were shown to increase with system complexity. Prior to this research, the variation in blending times caused discrepancies between CFD models and experiments. This research addressed this discrepancy, and determined statistical correction factors that can be applied to CFD models, and thereby quantified techniques to permit the application of CFD models to complex systems, such as blending. These blending time correction factors for CFD models are comparable to safety factors used in structural design, and compensate variability that cannot be theoretically calculated. To determine these correction factors, research was performed to investigate blending, using a pump with dual opposing jets which re-circulate fluids in the tank to promote blending when fluids are added to the tank. In all, eighty-five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of vertical cooling coils below the liquid surface for a full scale, liquid radioactive waste storage tank. Also, different jet

  2. Development of a three-dimensional CFD model for rotary lime kilns

    Energy Technology Data Exchange (ETDEWEB)

    Lixin Tao; Blom, Roger (FS Dynamics Sweden AB, Goeteborg (Sweden)); Nordgren, Daniel (Innventia, Stockholm (Sweden))

    2010-11-15

    In the calcium loop of the recovery cycle in a Kraft process of pulp and paper production, rotary lime kilns are used to convert the lime mud, mainly CaCO3, back to quick lime, CaO, for re-use in the causticizing process. The lime kilns are one of the major energy consumption devices for paper and pulp industry. Because of the rising oil price and new emission limits, the pulp mills have been forced to look for alternative fuels for their lime kilns. One interesting alternative to oil, often easily available at pulp mills, is biofuels such as sawdust and bark. However the practical kiln operation often encounters some difficulties because of the uncertainties around the biofuel impact on the lime kiln performance. A deeper understanding of the flame characteristics is required when shifting from oil to biofuels. Fortunately recent advances in modern Computational Fluid Dynamics, CFD, have provided the possibility to study and predict the detailed flame characteristics regarding the lime kiln performance. In this project a three-dimensional CFD model for rotary lime kilns has been developed. To simulate a rotary lime kiln the developed CFD model integrates the three essential sub-models, i.e. the freeboard hot flow model, the lime bed model and the rotating refractory wall model and it is developed based on the modern CFD package: FLUENT which is commercially available on the market. The numerical simulations using the developed CFD model have been performed for three selected kiln operations fired with three different fuel mixtures. The predicted results from the CFD modelling are presented and discussed in order to compare the impacts on the kiln performance due to the different firing conditions. During the development, the lime kiln at the Soedra Cell Moensteraas mill has been used as reference kiln. To validate the CFD model, in-plant measurements were carried out in the Moensteraas lime kiln during an experiment campaign. The results obtained from the

  3. Computation of the stability derivatives via CFD and the sensitivity equations

    Science.gov (United States)

    Lei, Guo-Dong; Ren, Yu-Xin

    2011-04-01

    The method to calculate the aerodynamic stability derivates of aircrafts by using the sensitivity equations is extended to flows with shock waves in this paper. Using the newly developed second-order cell-centered finite volume scheme on the unstructured-grid, the unsteady Euler equations and sensitivity equations are solved simultaneously in a non-inertial frame of reference, so that the aerodynamic stability derivatives can be calculated for aircrafts with complex geometries. Based on the numerical results, behavior of the aerodynamic sensitivity parameters near the shock wave is discussed. Furthermore, the stability derivatives are analyzed for supersonic and hypersonic flows. The numerical results of the stability derivatives are found in good agreement with theoretical results for supersonic flows, and variations of the aerodynamic force and moment predicted by the stability derivatives are very close to those obtained by CFD simulation for both supersonic and hypersonic flows.

  4. Assessment of Turbulent CFD Against STS-128 Hypersonic Flight Data

    Science.gov (United States)

    Wood, William A.; Kleb, William L.; Hyatt, Andrew J.

    2010-01-01

    Turbulent CFD simulations are compared against surface temperature measurements of the space shuttle orbiter windward tiles at reentry flight conditions. Algebraic turbulence models are used within both the LAURA and DPLR CFD codes. The flight data are from temperature measurements obtained by seven thermocouples during the STS-128 mission (September 2009). The flight data indicate boundary layer transition onset over the Mach number range 13.5{15.5, depending upon the location on the vehicle. But the boundary layer flow appeared to be transitional down through Mach 12, based upon the flight data and CFD trends. At Mach 9 the simulations match the flight data on average within 20 F/11 C, where typical surface temperatures were approximately 1600 F/870 C.

  5. Design of 500kW grate fired test facility using CFD

    DEFF Research Database (Denmark)

    Rosendahl, Lasse Aistrup; Kær, Søren Knudsen; Jørgensen, K.

    2005-01-01

    A 500kW vibrating grate fired test facility for solid biomass fuels has been designed using numerical models including CFD. The CFD modelling has focussed on the nozzle layout and flowpatterns in the lower part of the furnace, and the results have established confidence in the chosen design...

  6. Requirements for facilities and measurement techniques to support CFD development for hypersonic aircraft

    Science.gov (United States)

    Sellers, William L., III; Dwoyer, Douglas L.

    1992-01-01

    The design of a hypersonic aircraft poses unique challenges to the engineering community. Problems with duplicating flight conditions in ground based facilities have made performance predictions risky. Computational fluid dynamics (CFD) has been proposed as an additional means of providing design data. At the present time, CFD codes are being validated based on sparse experimental data and then used to predict performance at flight conditions with generally unknown levels of uncertainty. This paper will discuss the facility and measurement techniques that are required to support CFD development for the design of hypersonic aircraft. Illustrations are given of recent success in combining experimental and direct numerical simulation in CFD model development and validation for hypersonic perfect gas flows.

  7. CFD simulation research on residential indoor air quality.

    Science.gov (United States)

    Yang, Li; Ye, Miao; He, Bao-Jie

    2014-02-15

    Nowadays people are excessively depending on air conditioning to create a comfortable indoor environment, but it could cause some health problems in a long run. In this paper, wind velocity field, temperature field and air age field in a bedroom with wall-hanging air conditioning running in summer are analyzed by CFD numerical simulation technology. The results show that wall-hanging air conditioning system can undertake indoor heat load and conduct good indoor thermal comfort. In terms of wind velocity, air speed in activity area where people sit and stand is moderate, most of which cannot feel wind flow and meet the summer indoor wind comfort requirement. However, for air quality, there are local areas without ventilation and toxic gases not discharged in time. Therefore it is necessary to take effective measures to improve air quality. Compared with the traditional measurement method, CFD software has many advantages in simulating indoor environment, so it is hopeful for humans to create a more comfortable, healthy living environment by CFD in the future. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Grid deformation strategies for CFD analysis of screw compressors

    OpenAIRE

    Rane, S.; Kovacevic, A.; Stosic, N.; Kethidi, M.

    2013-01-01

    Customized grid generation of twin screw machines for CFD analysis is widely used by the refrigeration and air-conditioning industry today, but is currently not suitable for topologies such as those of single screw, variable pitch or tri screw rotors. This paper investigates a technique called key-frame re-meshing that supplies pre-generated unstructured grids to the CFD solver at different time steps. To evaluate its accuracy, the results of an isentropic compression-expansion process in a r...

  9. Calculation of Post-Closure Natural Convection Heat and Mass Transfer in Yucca Mountain Drifts

    International Nuclear Information System (INIS)

    Webb, S.; Itamura, M.

    2004-01-01

    Natural convection heat and mass transfer under post-closure conditions has been calculated for Yucca Mountain drifts using the computational fluid dynamics (CFD) code FLUENT. Calculations have been performed for 300, 1000, 3000, and 10,000 years after repository closure. Effective dispersion coefficients that can be used to calculate mass transfer in the drift have been evaluated as a function of time and boundary temperature tilt

  10. Adaptive Distributed Data Structure Management for Parallel CFD Applications

    KAUST Repository

    Frisch, Jerome

    2013-09-01

    Computational fluid dynamics (CFD) simulations require a lot of computing resources in terms of CPU time and memory in order to compute with a reasonable physical accuracy. If only uniformly refined domains are applied, the amount of computing cells is growing rather fast if a certain small resolution is physically required. This can be remedied by applying adaptively refined grids. Unfortunately, due to the adaptive refinement procedures, errors are introduced which have to be taken into account. This paper is focussing on implementation details of the applied adaptive data structure management and a qualitative analysis of the introduced errors by analysing a Poisson problem on the given data structure, which has to be solved in every time step of a CFD analysis. Furthermore an adaptive CFD benchmark example is computed, showing the benefits of an adaptive refinement as well as measurements of parallel data distribution and performance. © 2013 IEEE.

  11. OpenFOAM: Open source CFD in research and industry

    Directory of Open Access Journals (Sweden)

    Hrvoje Jasak

    2009-12-01

    Full Text Available The current focus of development in industrial Computational Fluid Dynamics (CFD is integration of CFD into Computer-Aided product development, geometrical optimisation, robust design and similar. On the other hand, in CFD research aims to extend the boundaries of practical engineering use in “non-traditional” areas. Requirements of computational flexibility and code integration are contradictory: a change of coding paradigm, with object orientation, library components, equation mimicking is proposed as a way forward. This paper describes OpenFOAM, a C++ object oriented library for Computational Continuum Mechanics (CCM developed by the author. Efficient and flexible implementation of complex physical models is achieved by mimicking the form of partial differential equation in software, with code functionality provided in library form. Open Source deployment and development model allows the user to achieve desired versatility in physical modeling without the sacrifice of complex geometry support and execution efficiency.

  12. SFO-Project: The New Generation of Sharable, Editable and Open-Access CFD Tutorials

    Science.gov (United States)

    Javaherchi, Teymour; Javaherchi, Ardeshir; Aliseda, Alberto

    2016-11-01

    One of the most common approaches to develop a Computational Fluid Dynamic (CFD) simulation for a new case study of interest is to search for the most similar, previously developed and validated CFD simulation among other works. A simple search would result into a pool of written/visual tutorials. However, users should spend significant amount of time and effort to find the most correct, compatible and valid tutorial in this pool and further modify it toward their simulation of interest. SFO is an open-source project with the core idea of saving the above-mentioned time and effort. This is done via documenting/sharing scientific and methodological approaches to develop CFD simulations for a wide spectrum of fundamental and industrial case studies in three different CFD solvers; STAR-CCM +, FLUENT and Open FOAM (SFO). All of the steps and required files of these tutorials are accessible and editable under the common roof of Github (a web-based Git repository hosting service). In this presentation we will present the current library of 20 + developed CFD tutorials, discuss the idea and benefit of using them, their educational values and explain how the next generation of open-access and live resource of CFD tutorials can be built further hand-in-hand within our community.

  13. CFD analysis of a diaphragm free-piston Stirling cryocooler

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-10-01

    This paper presents a Computational Fluid Dynamics (CFD) analysis of a novel free-piston Stirling cryocooler that uses a pair of metal diaphragms to seal and suspend the displacer. The diaphragms allow the displacer to move without rubbing or moving seals. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicated the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. The diaphragm's large diameter and short stroke produces a significant radial component to the oscillating flow fields inside the cryocooler which were not modelled in the one-dimensional analysis tool Sage that was used to design the prototypes. Compared with standard pistons, the diaphragm geometry increases the gas-to-wall heat transfer due to the higher velocities and smaller hydraulic diameters. A Computational Fluid Dynamics (CFD) model of the cryocooler was constructed to understand the underlying fluid-dynamics and heat transfer mechanisms with the aim of further improving performance. The CFD modelling of the heat transfer in the radial flow fields created by the diaphragms shows the possibility of utilizing the flat geometry for heat transfer, reducing the need for, and the size of, expensive heat exchangers. This paper presents details of a CFD analysis used to model the flow and gas-to-wall heat transfer inside the second prototype cryocooler, including experimental validation of the CFD to produce a robust analysis.

  14. Hypersonic CFD applications for the National Aero-Space Plane

    Science.gov (United States)

    Richardson, Pamela F.; Mcclinton, Charles R.; Bittner, Robert D.; Dilley, A. Douglas; Edwards, Kelvin W.

    1989-01-01

    Design and analysis of the NASP depends heavily upon developing the critical technology areas that cover the entire engineering design of the vehicle. These areas include materials, structures, propulsion systems, propellants, integration of airframe and propulsion systems, controls, subsystems, and aerodynamics areas. Currently, verification of many of the classical engineering tools relies heavily on computational fluid dynamics. Advances are being made in the development of CFD codes to accomplish nose-to-tail analyses for hypersonic aircraft. Additional details involving the partial development, analysis, verification, and application of the CFL3D code and the SPARK combustor code are discussed. A nonequilibrium version of CFL3D that is presently being developed and tested is also described. Examples are given of portion calculations for research hypersonic aircraft geometries and comparisons with experiment data show good agreement.

  15. Validation of NEPTUNE-CFD on ULPU-V experiments

    Energy Technology Data Exchange (ETDEWEB)

    Jamet, Mathieu, E-mail: mathieu.jamet@edf.fr; Lavieville, Jerome; Atkhen, Kresna; Mechitoua, Namane

    2015-11-15

    In-vessel retention (IVR) of molten corium through external cooling of the reactor pressure vessel is one possible means of severe accident mitigation for a class of nuclear power plants. The aim is to successfully terminate the progression of a core melt within the reactor vessel. The probability of success depends on the efficacy of the cooling strategy; hence one of the key aspects of an IVR demonstration relates to the heat removal capability through the vessel wall by convection and boiling in the external water flow. This is only possible if the in-vessel thermal loading is lower than the local critical heat flux expected along the outer wall of the vessel, which is in turn highly dependent on the flow characteristics between the vessel and the insulator. The NEPTUNE-CFD multiphase flow solver is used to obtain a better understanding at local scale of the thermal hydraulics involved in this situation. The validation of the NEPTUNE-CFD code on the ULPU-V facility experiments carried out at the University of California Santa Barbara is presented as a first attempt of using CFD codes at EDF to address such an issue. Two types of computation are performed. On the one hand, a steady state algorithm is used to compute natural circulation flow rates and differential pressures and, on the other, a transient algorithm computation reveals the oscillatory nature of the pressure data recorded in the ULPU facility. Several dominant frequencies are highlighted. In both cases, the CFD simulations reproduce reasonably well the experimental data for these quantities.

  16. CFD analysis of cascade effects in marine propellers with trailing edge modification

    DEFF Research Database (Denmark)

    Shin, Keun Woo; Andersen, Poul

    2015-01-01

    investigated intensively by viscous flow solvers, although RANS CFD is prevalent in marine industry nowadays. In the current work, the cascade effect of a marine propeller is analyzed by CFD simulations on a threedimensional propeller model with varying the number of blades. The influence of trailing......-edge configurations on the cascade effect is also investigated by simulating CFD with varying trailingedge thickness and slope. The reason why the trailingedge is handled rather than other parts of bladegeometry is that it can be modified without altering overall blade thrust significantly, because the loading...

  17. CFD-FEM coupling for accurate prediction of thermal fatigue

    International Nuclear Information System (INIS)

    Hannink, M.H.C.; Kuczaj, A.K.; Blom, F.J.; Church, J.M.; Komen, E.M.J.

    2009-01-01

    Thermal fatigue is a safety related issue in primary pipework systems of nuclear power plants. Life extension of current reactors and the design of a next generation of new reactors lead to growing importance of research in this direction. The thermal fatigue degradation mechanism is induced by temperature fluctuations in a fluid, which arise from mixing of hot and cold flows. Accompanied physical phenomena include thermal stratification, thermal striping, and turbulence [1]. Current plant instrumentation systems allow monitoring of possible causes as stratification and temperature gradients at fatigue susceptible locations [1]. However, high-cycle temperature fluctuations associated with turbulent mixing cannot be adequately detected by common thermocouple instrumentations. For a proper evaluation of thermal fatigue, therefore, numerical simulations are necessary that couple instantaneous fluid and solid interactions. In this work, a strategy for the numerical prediction of thermal fatigue is presented. The approach couples Computational Fluid Dynamics (CFD) and the Finite Element Method (FEM). For the development of the computational approach, a classical test case for the investigation of thermal fatigue problems is studied, i.e. mixing in a T-junction. Due to turbulent mixing of hot and cold fluids in two perpendicularly connected pipes, temperature fluctuations arise in the mixing zone downstream in the flow. Subsequently, these temperature fluctuations are also induced in the pipes. The stresses that arise due to the fluctuations may eventually lead to thermal fatigue. In the first step of the applied procedure, the temperature fluctuations in both fluid and structure are calculated using the CFD method. Subsequently, the temperature fluctuations in the structure are imposed as thermal loads in a FEM model of the pipes. A mechanical analysis is then performed to determine the thermal stresses, which are used to predict the fatigue lifetime of the structure

  18. Investigation of the condensing vapor bubble behavior through CFD simulation

    International Nuclear Information System (INIS)

    Sablania, Sidharth; Verma, Akash; Goyal, P.; Dutta, Anu; Singh, R.K.

    2013-09-01

    In nuclear systems the sub-cooled boiling flow is an important problem due to the behavior of condensing vapor bubble which has a large effect on the heat transfer characteristics as well as pressure drops and flow instability. The sub-cooled boiling flows become very complex and dynamic phenomena by the vapor bubble-water interaction. This happens due to the boiling/condensation, break-up, and coalescence of the bubble and needs to be addressed for characterizing the above mentioned flow parameters. There have been many researches to analyze the behavior of bubble experimentally and analytically. However, it is very difficult to get complete information about the behavior of bubble because of ever changing interface between vapor and water phase due to bubble condensation/evaporation Therefore, it is necessary to carry out a CFD simulation for better understanding the complex phenomenon of the bubble behavior. The present work focuses on the simulation of condensing bubble in subcooled boiling flow using (Volume of Fluid) VOF method in the CFD code CFD-ACE+. In order to simulate the heat and mass transfer through the bubble interface, CFD modeling for the bubble condensation was developed by modeling the source terms in the governing equations of VOF model using the User-Defined Function (UDF) in CFD-ACE+ code. The effect of condensation on bubble behavior was analyzed by comparing the behavior of condensing bubble with that of adiabatic bubble. It was observed that the behavior of condensing bubble was different from that of non condensing bubble in respect of bubble shape, diameter, velocity etc. The results obtained from the present simulation in terms of various parameters such as bubble velocity, interfacial area and bubble volume agreed well with the reported experimental results verified with FLUENT code in available literature. Hence, this CFD-ACE+ simulation of single bubble condensation will be a useful computational fluid dynamics tool for analyzing the

  19. CFD Modeling of a Multiphase Gravity Separator Vessel

    KAUST Repository

    Narayan, Gautham

    2017-05-23

    The poster highlights a CFD study that incorporates a combined Eulerian multi-fluid multiphase and a Population Balance Model (PBM) to study the flow inside a typical multiphase gravity separator vessel (GSV) found in oil and gas industry. The simulations were performed using Ansys Fluent CFD package running on KAUST supercomputer, Shaheen. Also, a highlight of a scalability study is presented. The effect of I/O bottlenecks and using Hierarchical Data Format (HDF5) for collective and independent parallel reading of case file is presented. This work is an outcome of a research collaboration on an Aramco project on Shaheen.

  20. CFD Modeling of a Multiphase Gravity Separator Vessel

    KAUST Repository

    Narayan, Gautham; Khurram, Rooh Ul Amin; Elsaadawy, Ehab

    2017-01-01

    The poster highlights a CFD study that incorporates a combined Eulerian multi-fluid multiphase and a Population Balance Model (PBM) to study the flow inside a typical multiphase gravity separator vessel (GSV) found in oil and gas industry. The simulations were performed using Ansys Fluent CFD package running on KAUST supercomputer, Shaheen. Also, a highlight of a scalability study is presented. The effect of I/O bottlenecks and using Hierarchical Data Format (HDF5) for collective and independent parallel reading of case file is presented. This work is an outcome of a research collaboration on an Aramco project on Shaheen.

  1. ANALISIS SENSITIVITAS TURBULENSI ALIRAN PADA KANAL BAHAN BAKAR PWR BERBASIS CFD

    Directory of Open Access Journals (Sweden)

    Endiah Puji Hastuti

    2015-04-01

    yang sangat lama dan membutuhkan memori yang besar. Kata kunci: aliran turbulen, kanal PWR, CFD, tunak, transien   Coolant flow turbulence on heat transfer process serves to enhance the heat transfer coefficient, likewise flow in the fuel sub channel. Computational fluid dynamic program, FLUENT is a computational program based on finite element, that is able to predict and analyze the dynamics of fluid flow phenomena, accurately. CFD calculation program is selected in this study because of its accurately and it also can provide good visualization. Purpose of this research was to understand the characteristics of heat transfer, mass and momentum of the fuel rod to the coolant visually on: the temperature field, pressure field, and the kinetic energy field, as a function of the flow dynamics within fuel channel, on steady state and transient condition. Analysis of flow dynamics in the fuel channel base on CFD was done by using the PWR sample data with reactor power of 1000 MWe on 17x17 array of fuel. To examine the sensitivity of the flow equation in accordance with the model of turbulent flow on fuel channel, the turbulence equation model of k-omega (Ƙ-ω, k-epsilon (Ƙ-ε, and Reynold stress model (RSM for steady state was used, while for transient turbulence model DES and LES are applied. In the sensitivity analysis of turbulent flow, hexahedral mesh model of three cell geometry each are 0.5 mm, 0.2 mm and 0.15 mm, was selected. The analysis shows that there are similar results of turbulen model Ƙ-ε and Ƙ-ω standard, on steady state analysis. Comparing with Dittus Boelter criteria for Nusselt number, the Reynolds stress model (RSM is recommended. Sensitivity analysis of mesh geometry between cell size 0.5 mm, 0.2 mm and 0.15 mm, indicating that the cell size of 0.5 mm was sufficient. Developed flow already reached on DES and LES model, however only for short time (3 seconds for transient condition. LES model need very long computation time and big memory

  2. A CFD model for the IEA-R1 reactor neat exchanger inlet nozzle flow

    International Nuclear Information System (INIS)

    Andrade, Delvonei A.; Angelo, Gabriel; Gainer, Gerson; Angelo, Edvaldo; Umbehaun, Pedro E.; Torres, Walmir M.; Sabundjian, Gaiane; Macedo, Luiz A.; Belchior Junior, Antonio; Conti, Thadeu N.; Watanabe, Bruno C.; Sakai, Caio C.

    2011-01-01

    A previous preliminary model of the IEA-R1 heat exchanger inlet nozzle flow was developed and published in the International Nuclear Atlantic Conference-INAC-2009. A new model was created based on the preliminary one. It was improved concerning the actual heat exchanger tube bundle geometry. This became a very special issue. Difficulties with the size of the numerical mesh came out pointing to our computational system limits. New CFD calculations with this improved model were performed using ANSYS-CFX. In this paper, we present this model and discuss the results. (author)

  3. A CFD model for the IEA-R1 reactor neat exchanger inlet nozzle flow

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Delvonei A.; Angelo, Gabriel; Gainer, Gerson; Angelo, Edvaldo; Umbehaun, Pedro E.; Torres, Walmir M.; Sabundjian, Gaiane; Macedo, Luiz A.; Belchior Junior, Antonio; Conti, Thadeu N.; Watanabe, Bruno C.; Sakai, Caio C., E-mail: delvonei@ipen.b, E-mail: gfainer@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    A previous preliminary model of the IEA-R1 heat exchanger inlet nozzle flow was developed and published in the International Nuclear Atlantic Conference-INAC-2009. A new model was created based on the preliminary one. It was improved concerning the actual heat exchanger tube bundle geometry. This became a very special issue. Difficulties with the size of the numerical mesh came out pointing to our computational system limits. New CFD calculations with this improved model were performed using ANSYS-CFX. In this paper, we present this model and discuss the results. (author)

  4. Uncertainty and Sensitivity Analyses for CFD Codes: an Attempt of a State of the Art on the Basis of the CEA Experience

    International Nuclear Information System (INIS)

    Crecy, Agnes de; Bazin, Pascal

    2013-01-01

    Uncertainty and sensitivity analyses, associated to best-estimate calculations become paramount for licensing processes and are known as BEPU (Best-Estimate Plus Uncertainties) methods. A recent activity such as the BEMUSE benchmark has shown that the present methods are mature enough for the system thermal-hydraulics codes, even if issues such as the quantification of the uncertainties of the input parameters, and especially, the physical models must be improved. But CFD codes are more and more used for fine 3-D modeling such as, for example, those necessary in dilution or stratification problems. The application of the BEPU methods to CFD codes becomes an issue that must be now addressed. That is precisely the goal of this paper. It consists of two main parts. In the chapter 2, the specificities of CFD codes for BEPU methods are listed, with focuses on the possible difficulties. In the chapter 3, the studies performed at CEA are described. It is important to note that CEA research in this field is only beginning and must not be viewed as a reference approach. (authors)

  5. Theoretical Study of Palladium Membrane Reactor Performance During Propane Dehydrogenation Using CFD Method

    Directory of Open Access Journals (Sweden)

    Kamran Ghasemzadeh

    2017-04-01

    Full Text Available This study presents a 2D-axisymmetric computational fluid dynamic (CFD model to investigate the performance Pd membrane reactor (MR during propane dehydrogenation process for hydrogen production. The proposed CFD model provided the local information of temperature and component concentration for the driving force analysis. After investigation of mesh independency of CFD model, the validation of CFD model results was carried out by other modeling data and a good agreement between CFD model results and theoretical data was achieved. Indeed, in the present model, a tubular reactor with length of 150 mm was considered, in which the Pt-Sn-K/Al2O3 as catalyst were filled in reaction zone. Hence, the effects of the important operating parameter (reaction temperature on the performances of membrane reactor (MR were studied in terms of propane conversion and hydrogen yield. The CFD results showed that the suggested MR system during propane dehydrogenation reaction presents higher performance with respect to once obtained in the conventional reactor (CR. In particular, by applying Pd membrane, was found that propane conversion can be increased from 41% to 49%. Moreover, the highest value of propane conversion (X = 91% was reached in case of Pd-Ag MR. It was also established that the feed flow rate of the MR is to be the one of the most important factors defining efficiency of the propane dehydrogenation process.

  6. CFD Numerical Simulation of the Complex Turbulent Flow Field in an Axial-Flow Water Pump

    Directory of Open Access Journals (Sweden)

    Wan-You Li

    2014-09-01

    Full Text Available Further optimal design of an axial-flow water pump calls for a thorough recognition of the characteristics of the complex turbulent flow field in the pump, which is however extremely difficult to be measured using the up-to-date experimental techniques. In this study, a numerical simulation procedure based on computational fluid dynamics (CFD was elaborated in order to obtain the fully three-dimensional unsteady turbulent flow field in an axial-flow water pump. The shear stress transport (SST k-ω model was employed in the CFD calculation to study the unsteady internal flow of the axial-flow pump. Upon the numerical simulation results, the characteristics of the velocity field and pressure field inside the impeller region were discussed in detail. The established model procedure in this study may provide guidance to the numerical simulations of turbomachines during the design phase or the investigation of flow and pressure field characteristics and performance. The presented information can be of reference value in further optimal design of the axial-flow pump.

  7. Lack of association of CFD polymorphisms with advanced age-related macular degeneration.

    Science.gov (United States)

    Zeng, Jiexi; Chen, Yuhong; Tong, Zongzhong; Zhou, Xinrong; Zhao, Chao; Wang, Kevin; Hughes, Guy; Kasuga, Daniel; Bedell, Matthew; Lee, Clara; Ferreyra, Henry; Kozak, Igor; Haw, Weldon; Guan, Jean; Shaw, Robert; Stevenson, William; Weishaar, Paul D; Nelson, Mark H; Tang, Luosheng; Zhang, Kang

    2010-11-03

    Age-related macular degeneration (AMD) is the most common cause of irreversible central vision loss worldwide. Research has linked AMD susceptibility with dysregulation of the complement cascade. Typically, complement factor H (CFH), complement factor B (CFB), complement component 2 (C2), and complement component 3 (C3) are associated with AMD. In this paper, we investigated the association between complement factor D (CFD), another factor of the complement system, and advanced AMD in a Caucasian population. Six single nucleotide polymorphisms (SNPs), rs1683564, rs35186399, rs1683563, rs3826945, rs34337649, and rs1651896, across the region covering CFD, were chosen for this study. One hundred and seventy-eight patients with advanced AMD and 161 age-matched normal controls were genotyped. Potential positive signals were further tested in another independent 445 advanced AMD patients and 190 controls. χ2 tests were performed to compare the allele frequencies between case and control groups. None of the six SNPs of CFD was found to be significantly associated with advanced AMD in our study. Our findings suggest that CFD may not play a major role in the genetic susceptibility to AMD because no association was found between the six SNPs analyzed in the CFD region and advanced AMD.

  8. An Eulerian-Eulerian CFD Simulation of Air-Water Flow in a Pipe Separator

    Directory of Open Access Journals (Sweden)

    E.A. Afolabi

    2014-06-01

    Full Text Available This paper presents a three dimensional Computational Fluid Dynamics (CFD of air-water flow using Eulerian –Eulerian multiphase model and RSM mixture turbulence model to investigate its hydrodynamic flow behaviour in a 30 mm pipe separator. The simulated results are then compared with the stereoscopic PIV measurements at different axial positions. The comparison shows that the velocity distribution can be predicted with high accuracy using CFD. The numerical velocity profiles are also found to be in good qualitative agreement with the experimental measurements. However, there were some discrepancies between the CFD results and the SPIV measurements at some axial positions away from the inlet section. Therefore, the CFD model could provide good physical understanding on the hydrodynamics flow behaviour for air-water in a pipe separator.

  9. Prediction and evaluation method of wind environment in the early design stage using BIM-based CFD simulation

    International Nuclear Information System (INIS)

    Lee, Sumi; Song, Doosam

    2010-01-01

    Drastic urbanization and manhattanization are causing various problems in wind environment. This study suggests a CFD simulation method to evaluate wind environment in the early design stage of high-rise buildings. The CFD simulation of this study is not a traditional in-depth simulation, but a method to immediately evaluate wind environment for each design alternative and provide guidelines for design modification. Thus, the CFD simulation of this study to evaluate wind environments uses BIM-based CFD tools to utilize building models in the design stage. This study examined previous criteria to evaluate wind environment for pedestrians around buildings and selected evaluation criteria applicable to the CFD simulation method of this study. Furthermore, proper mesh generation method and CPU time were reviewed to find a meaningful CFD simulation result for determining optimal design alternative from the perspective of wind environment in the design stage. In addition, this study is to suggest a wind environment evaluation method through a BIM-based CFD simulation.

  10. Computational Fluid Dynamics (CFD) Analysis Of Optical Payload For Lasercomm Science (OPALS) sealed enclosure module

    Science.gov (United States)

    Anderson, Kevin R.; Zayas, Daniel; Turner, Daniel

    2012-01-01

    Computational Fluid Dynamics (CFD) using the commercial CFD package CFDesign has been performed at NASA Jet Propulsion Laboratory (JPL) California Institute of Technology (Caltech) in support of the Phaeton Early Career Hire Program's Optical Payload for Lasercomm Science (OPALS) mission. The OPALS project is one which involves an International Space Station payload that will be using forced convection cooling in a hermetically sealed enclosure at 1 atm of air to cool "off-the-shelf" vendor electronics. The CFD analysis was used to characterize the thermal and fluid flow environment within a complicated labyrinth of electronics boards, fans, instrumentation, harnessing, ductwork and heat exchanger fins. The paradigm of iteratively using CAD/CAE tools and CFD was followed in order to determine the optimum flow geometry and heat sink configuration to yield operational convective film coefficients and temperature survivability limits for the electronics payload. Results from this current CFD analysis and correlation of the CFD model against thermal test data will be presented. Lessons learned and coupled thermal / flow modeling strategies will be shared in this paper.

  11. Application of a CFD based containment model to different large-scale hydrogen distribution experiments

    International Nuclear Information System (INIS)

    Visser, D.C.; Siccama, N.B.; Jayaraju, S.T.; Komen, E.M.J.

    2014-01-01

    Highlights: • A CFD based model developed in ANSYS-FLUENT for simulating the distribution of hydrogen in the containment of a nuclear power plant during a severe accident is validated against four large-scale experiments. • The successive formation and mixing of a stratified gas-layer in experiments performed in the THAI and PANDA facilities are predicted well by the CFD model. • The pressure evolution and related condensation rate during different mixed convection flow conditions in the TOSQAN facility are predicted well by the CFD model. • The results give confidence in the general applicability of the CFD model and model settings. - Abstract: In the event of core degradation during a severe accident in water-cooled nuclear power plants (NPPs), large amounts of hydrogen are generated that may be released into the reactor containment. As the hydrogen mixes with the air in the containment, it can form a flammable mixture. Upon ignition it can damage relevant safety systems and put the integrity of the containment at risk. Despite the installation of mitigation measures, it has been recognized that the temporary existence of combustible or explosive gas clouds cannot be fully excluded during certain postulated accident scenarios. The distribution of hydrogen in the containment and mitigation of the risk are, therefore, important safety issues for NPPs. Complementary to lumped parameter code modelling, Computational Fluid Dynamics (CFD) modelling is needed for the detailed assessment of the hydrogen risk in the containment and for the optimal design of hydrogen mitigation systems in order to reduce this risk as far as possible. The CFD model applied by NRG makes use of the well-developed basic features of the commercial CFD package ANSYS-FLUENT. This general purpose CFD package is complemented with specific user-defined sub-models required to capture the relevant thermal-hydraulic phenomena in the containment during a severe accident as well as the effect of

  12. Application of a CFD based containment model to different large-scale hydrogen distribution experiments

    Energy Technology Data Exchange (ETDEWEB)

    Visser, D.C., E-mail: visser@nrg.eu; Siccama, N.B.; Jayaraju, S.T.; Komen, E.M.J.

    2014-10-15

    Highlights: • A CFD based model developed in ANSYS-FLUENT for simulating the distribution of hydrogen in the containment of a nuclear power plant during a severe accident is validated against four large-scale experiments. • The successive formation and mixing of a stratified gas-layer in experiments performed in the THAI and PANDA facilities are predicted well by the CFD model. • The pressure evolution and related condensation rate during different mixed convection flow conditions in the TOSQAN facility are predicted well by the CFD model. • The results give confidence in the general applicability of the CFD model and model settings. - Abstract: In the event of core degradation during a severe accident in water-cooled nuclear power plants (NPPs), large amounts of hydrogen are generated that may be released into the reactor containment. As the hydrogen mixes with the air in the containment, it can form a flammable mixture. Upon ignition it can damage relevant safety systems and put the integrity of the containment at risk. Despite the installation of mitigation measures, it has been recognized that the temporary existence of combustible or explosive gas clouds cannot be fully excluded during certain postulated accident scenarios. The distribution of hydrogen in the containment and mitigation of the risk are, therefore, important safety issues for NPPs. Complementary to lumped parameter code modelling, Computational Fluid Dynamics (CFD) modelling is needed for the detailed assessment of the hydrogen risk in the containment and for the optimal design of hydrogen mitigation systems in order to reduce this risk as far as possible. The CFD model applied by NRG makes use of the well-developed basic features of the commercial CFD package ANSYS-FLUENT. This general purpose CFD package is complemented with specific user-defined sub-models required to capture the relevant thermal-hydraulic phenomena in the containment during a severe accident as well as the effect of

  13. CFD simulation of solids suspension in stirred tanks: Review

    Directory of Open Access Journals (Sweden)

    Ochieng Aoyi

    2010-01-01

    Full Text Available Many chemical reactions are carried out using stirred tanks, and the efficiency of such systems depends on the quality of mixing, which has been a subject of research for many years. For solid-liquid mixing, traditionally the research efforts were geared towards determining mixing features such as off-bottom solid suspension using experimental techniques. In a few studies that focused on the determination of solids concentration distribution, some methods that have been used have not been accurate enough to account for some small scale flow mal-distribution such as the existence of dead zones. The present review shows that computational fluid dynamic (CFD techniques can be used to simulate mixing features such as solids off-bottom suspension, solids concentration and particle size distribution and cloud height. Information on the effects of particle size and particle size distribution on the solids concentration distribution is still scarce. Advancement of the CFD modeling is towards coupling the physical and kinetic data to capture mixing and reaction at meso- and micro-scales. Solids residence time distribution is important for the design; however, the current CFD models do not predict this parameter. Some advances have been made in recent years to apply CFD simulation to systems that involve fermentation and anaerobic processes. In these systems, complex interaction between the biochemical process and the hydrodynamics is still not well understood. This is one of the areas that still need more attention.

  14. CFD thermal-hydraulic analysis of a CANDU fuel channel

    International Nuclear Information System (INIS)

    Catana, A.; Prisecaru, I.; Dupleac, D.; Danila, N.

    2009-01-01

    This paper presents the numerical investigation of a CANDU fuel channel using CFD (Computational fluid dynamics) methodology approach. Limited computer power available at Bucharest University POLITEHNICA forced the authors to analyse only segments of fuel channel namely the significant ones: fuel bundle junctions with adjacent segments, fuel bundle spacer planes with adjacent segments, regular segments of fuel bundles. The computer code used is FLUENT. Fuel bundles contained in pressure tubes forms a complex flow domain. The flow is characterized by high turbulence and in some parts of fuel channel also by multi-phase flow. The flow in the fuel channel has been simulated by solving the equations for conservation of mass and momentum. For turbulence modelling the standard k-e model is employed although other turbulence models can be used as well. In this paper we do not consider heat generation and heat transfer capabilities of CFD methods. Since we consider only some relatively short segments of a CANDU fuel channel we can assume, for this starting stage, that heat transfer is not very important for these short segments of fuel channel. The boundary conditions for CFD analysis are provided by system and sub-channel analysis. In this paper the discussion is focused on some flow parameters behaviour at the bundle junction, spacer's plane configuration, etc. In this paper we present results for Standard CANDU 6 Fuel Bundles as a basis for CFD thermal-hydraulic analysis of INR proposed SEU43 and other new nuclear fuels. (authors)

  15. Multiphase CFD simulation of a solid bowl centrifuge

    Energy Technology Data Exchange (ETDEWEB)

    Romani Fernandez, X.; Nirschl, H. [Universitaet Karlsruhe, Institut fuer MVM, Karlsruhe (Germany)

    2009-05-15

    This study presents some results from the numerical simulation of the flow in an industrial solid bowl centrifuge used for particle separation in industrial fluid processing. The computational fluid dynamics (CFD) software Fluent was used to simulate this multiphase flow. Simplified two-dimensional and three-dimensional geometries were built and meshed from the real centrifuge geometry. The CFD results show a boundary layer of axially fast moving fluid at the gas-liquid interface. Below this layer there is a thin recirculation. The obtained tangential velocity values are lower than the ones for the rigid-body motion. Also, the trajectories of the solid particles are evaluated. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  16. CFD Modelling in Screw Compressors With Complex Multi Rotor Configurations

    OpenAIRE

    Rane, Sham Ramchandra; Kovacevic, Ahmed; Kethidi, Madhulika

    2012-01-01

    Computational Fluid Dynamics (CFD) of screw compressors is challenging due to the positive displacement nature of the process, existence of very fine fluid leakage paths, coexistence of working fluid and lubricant or coolant, fluid injection and most importantly the lack of methodologies available to generate meshes required for the full three dimensional transient simulations. In this paper, currently available technology of grid remeshing has been used to demonstrate the CFD simulations of ...

  17. The Test for Flow Characteristics of Tubular Fuel Assembly(II) - Experimental results and CFD analysis

    International Nuclear Information System (INIS)

    Park, Jong Hark; Chae, H. T.; Park, C.; Kim, H.

    2006-12-01

    A test facility had been established for the experiment of velocity distribution and pressure drop in a tubular fuel. A basic test had been conducted to examine the performance of the test loop and to verify the accuracy of measurement by pitot-tube. In this report, test results and CFD analysis for the hydraulic characteristics of a tubular fuel, following the previous tests, are described. Coolant velocities in all channels were measured using pitot-tube and the effect of flow rate change on the velocity distribution was also examined. The pressure drop through the tubular fuel was measured for various flow rates in range of 1 kg/s to 21 kg/s to obtain a correlation of pressure drop with variation of flow rate. In addition, a CFD(Computational Fluid Dynamics) analysis was also done to find out the hydraulic characteristics of tubular fuel such as velocity distribution and pressure drop. As the results of CFD analysis can give us a detail insight on coolant flow in the tubular fuel, the CFD method is a very useful tool to understand the flow structure and phenomena induced by fluid flow. The CFX-10, a commercial CFD code, was used in this study. The two results by the experiment and the CFD analysis were investigated and compared with each other. Overall trend of velocity distribution by CFD analysis was somewhat different from that of experiment, but it would be reasonable considering measurement uncertainties. The CFD prediction for pressure drop of a tubular fuel shows a tolerably good agreement with experiment within 8% difference

  18. CFD analysis of premixed hydrogen/air combustion in an upright, rectangular shaped combustion chamber

    International Nuclear Information System (INIS)

    Gera, B.; Singh, R.K.; Vaze, K.K.

    2014-01-01

    Premixed hydrogen/air combustion in an upright, rectangular shaped combustion chamber has been performed numerically using commercial CFD code CFD-ACE+. The combustion chamber had dimensions 1 m X 0.024 m X 1 m. Simulations were carried out for 10% (v/v) hydrogen concentration for which experimental results were available. Effect of different boundary condition and ignition position on flame propagation was studied. Time dependent flame propagation in the chamber was predicted by CFD code. The computed transient flame propagation in the chamber was in good agreement with experimental results. The present work demonstrated that the available commercial CFD codes are capable of modeling hydrogen deflagration in a realistic manner. (author)

  19. PIV and Rotational Raman-Based Temperature Measurements for CFD Validation in a Single Injector Cooling Flow

    Science.gov (United States)

    Wernet, Mark P.; Georgiadis, Nicholas J.; Locke, Randy J.

    2018-01-01

    Film cooling is used in a wide variety of engineering applications for protection of surfaces from hot or combusting gases. The design of more efficient thin film cooling geometries/configurations could be facilitated by an ability to accurately model and predict the effectiveness of current designs using computational fluid dynamics (CFD) code predictions. Hence, a benchmark set of flow field property data were obtained for use in assessing current CFD capabilities and for development of better turbulence models. Both Particle Image Velocimetry (PIV) and spontaneous rotational Raman scattering (SRS) spectroscopy were used to acquire high quality, spatially-resolved measurements of the mean velocity, turbulence intensity and also the mean temperature and normalized root mean square (rms) temperatures in a single injector cooling flow arrangement. In addition to flowfield measurements, thermocouple measurements on the plate surface enabled estimates of the film effectiveness. Raman spectra in air were obtained across a matrix of radial and axial locations downstream from a 68.07 mm square nozzle blowing heated air over a range of temperatures and Mach numbers, across a 30.48cm long plate equipped with a single injector cooling hole. In addition, both centerline streamwise 2-component PIV and cross-stream 3-component Stereo PIV data at 15 axial stations were collected in the same flows. The velocity and temperature data were then compared against Wind-US CFD code predictions for the same flow conditions. The results of this and planned follow-on studies will support NASA's development and assessment of turbulence models for heated flows.

  20. Artificial neural networks applied to DNBR calculation in digital core protection systems

    International Nuclear Information System (INIS)

    Lee, H. C.; Chang, S. H.

    2003-01-01

    The nuclear power plant has to be operated with sufficient margin from the specified DNBR limit for assuring its safety. The digital core protection system calculates on-line real-time DNBR by using a complex subchannel analysis program, and triggers a reliable reactor shutdown if the calculated DNBR approaches the specified limit. However, it takes relatively long calculation time even for a steady state condition, which may have an adverse effect on the operation flexibility. To overcome the drawback, a method using artificial neural networks is studied in this paper. Nonparametric training approach is utilized, which shows dramatic reduction of the training time, no tedious heuristic process for optimizing parameters, and no local minima problem during the training. The test results show that the predicted DNBR is within about ±2% deviation from the target DNBR for the fixed axial flux shape case. For the variable axial flux case including severely skewed shapes appeared during accidents, the deviation is about ±10∼15%. The suggested method could be the alternative that can calculate DNBR very quickly while increasing the plant availability

  1. ARC Code TI: CFD Utility Software Library

    Data.gov (United States)

    National Aeronautics and Space Administration — The CFD Utility Software Library consists of nearly 30 libraries of Fortran 90 and 77 subroutines and almost 100 applications built on those libraries. Many of the...

  2. PIV, radiotracers and CFD for flow anomalies

    International Nuclear Information System (INIS)

    Houdek, P.; Reitspiesova, I.; Zitny, R.; Thyn, J.

    2004-01-01

    Experimental investigation of flow asymmetries in continuous direct ohmic heater by using PIV and stimulus response technique (radioisotope 99 Tc) is presented together with CFD modelling by using finite element code FEMINA. (author)

  3. CFD analysis of heat transfer in a vertical annular gas gap

    International Nuclear Information System (INIS)

    Borgohain, A.; Maheshwari, N.K.; Vijayan, P.K.

    2011-01-01

    Heat transfer analysis in a vertical annulus is carried out by using a CFD code TRIO-U. The results are used to understand heat transfer in the vertical annulus. An experimental study is taken from literature for the CFD analysis. The geometry of the test section of the experiment is simulated in TRIO-U. The operating conditions of the experiment are simulated by imposing appropriate boundary conditions. Three modes of the heat transfer, conduction, radiation and convection in the gas gap are considered in the analysis. From the analysis it is found that TRIO-U can successfully handle all modes heat transfer. The theoretical results for heat transfer have been compared with experimental data. This paper deals with the detailed CFD modelling and analysis. (author)

  4. Calculation of Flows Over Underwater Bodies with Hull, Sail and Appendages

    International Nuclear Information System (INIS)

    Shoab, M.; Ayub, M.; Bilal, S.; Zahir, S.; Khan, M.A.

    2004-01-01

    A comprehensive study has been made for the hydrodynamic analysis of the submarine DARPA 2. The analysis was first performed for hull, then hull with sail on top and then for the complete submarine including hull, sail and appendages. A comparison of tangential velocity and pressure distribution for hull is accomplished using CFD flow solvers and published data. Further, the pressure distribution over the hull with sail is also analyzed. Finally, pressure distribution, forces and moments were calculated over the complete submarine including hull, sail and appendages. Comparison 01 pressure distribution and tangential velocity for the hull show a good agreement with published data. Pressure coefficient comparison for the hull with sail shows the good CFD-CFD agreement. Comparison of Normal force and pitching moment of complete submarine having hull, sail and appendages shows a reasonable agreement with the experimental results of DARPA 2. Both quantitative and qualitative analysis of the complete submarine estimates the required design force and moment at different angles of attack and also demonstrate the flow visualization. (author)

  5. MHD for fusion: parameters bridge between CFD tools and system codes; MHD para fusion: parametros puente entre herramientas CFD y codigos de sistema

    Energy Technology Data Exchange (ETDEWEB)

    Batet, L.; Mas de les Valls, E.; Sedano, L. A.

    2012-07-01

    In the context of regenerating sheaths for fusion reactors, the CFD simulations of liquid metal channels (ML) are essential to know the phenomenology and obtain relevant information for design as: ML thermal gain, to know the thermal efficiency of the component, existence of hot spots, to define the materials to use, existence of flow inversion, etc. Apart from design parameters there are others, bridge parameter, required as inputs into system code. In this work shown GREENER/T4F capabilities for obtaining both parameters with a CFD tool based on open source OpenFOAM.

  6. Aeroelastic Stability of Suspension Bridges using CFD

    DEFF Research Database (Denmark)

    Stærdahl, Jesper Winther; Sørensen, Niels; Nielsen, Søren R.K.

    2007-01-01

    using CFD models and the aeroelastic stability boundary has been successfully determined when comparing two-dimensional flow situations using wind tunnel test data and CFD methods for the flow solution and two-degrees-of-freedom structural models in translation perpendicular to the flow direction......In recent years large span suspension bridges with very thin and slender profiles have been built without proportional increasing torsional and bending stiffness. As a consequence large deformations at the mid-span can occur with risk of aeroelastic instability and structural failure. Analysis...... of aeroelastic stability also named flutter stability is mostly based on semi-empirical engineering models, where model specific parameters, the so-called flutter derivatives, need calibration from wind tunnel tests or numerical methods. Several papers have been written about calibration of flutter derivatives...

  7. CFD modeling of thermal mixing in a T-junction geometry using LES model

    Energy Technology Data Exchange (ETDEWEB)

    Ayhan, Hueseyin, E-mail: huseyinayhan@hacettepe.edu.tr [Hacettepe University, Department of Nuclear Engineering, Beytepe, Ankara 06800 (Turkey); Soekmen, Cemal Niyazi, E-mail: cemalniyazi.sokmen@hacettepe.edu.tr [Hacettepe University, Department of Nuclear Engineering, Beytepe, Ankara 06800 (Turkey)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer CFD simulations of temperature and velocity fluctuations for thermal mixing cases in T-junction are performed. Black-Right-Pointing-Pointer It is found that the frequency range of 2-5 Hz contains most of the energy; therefore, may cause thermal fatigue. Black-Right-Pointing-Pointer This study shows that RANS based calculations fail to predict a realistic mixing between the fluids. Black-Right-Pointing-Pointer LES model can predict instantaneous turbulence behavior. - Abstract: Turbulent mixing of fluids at different temperatures can lead to temperature fluctuations at the pipe material. These fluctuations, or thermal striping, inducing cyclical thermal stresses and resulting thermal fatigue, may cause unexpected failure of pipe material. Therefore, an accurate characterization of temperature fluctuations is important in order to estimate the lifetime of pipe material. Thermal fatigue of the coolant circuits of nuclear power plants is one of the major issues in nuclear safety. To investigate thermal fatigue damage, the OECD/NEA has recently organized a blind benchmark study including some of results of present work for prediction of temperature and velocity fluctuations performing a thermal mixing experiment in a T-junction. This paper aims to estimate the frequency of velocity and temperature fluctuations in the mixing region using Computational Fluid Dynamics (CFD). Reynolds Averaged Navier-Stokes and Large Eddy Simulation (LES) models were used to simulate turbulence. CFD results were compared with the available experimental results. Predicted LES results, even in coarse mesh, were found to be in well-agreement with the experimental results in terms of amplitude and frequency of temperature and velocity fluctuations. Analysis of the temperature fluctuations and the power spectrum densities (PSD) at the locations having the strongest temperature fluctuations in the tee junction shows that the frequency range of 2-5 Hz

  8. Demonstration of Hybrid DSMC-CFD Capability for Nonequilibrium Reacting Flow

    Science.gov (United States)

    2018-02-09

    AFRL-RV-PS- TR-2018-0056 AFRL-RV-PS- TR-2018-0056 DEMONSTRATION OF HYBRID DSMC-CFD CAPABILITY FOR NONEQUILIBRIUM REACTING FLOW Thomas E...4. TITLE AND SUBTITLE Demonstration of Hybrid DSMC-CFD Capability for Nonequilibrium Reacting Flow 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9453-17-1...simulation codes. The models are based on new ab-intio rate data obtained using state -of-the-art potential energy surfaces for air species. A probability

  9. CFD Analysis on a Core Outlet Flow through the Fuel Alignment Plant of SMART

    International Nuclear Information System (INIS)

    Kim, Y. I.; Bae, Y. M.; Kim, K. K.

    2014-01-01

    CFD (Computational Fluid Dynamics) simulations were performed to confirm the core flow distribution for SMART, which acquired standard design approval in 2012. In this paper, CFD simulation is also used to calculate the pressure distribution of a core outlet, a Fuel Alignment Plate (FAP), for SMART. In SMART, the fluid discharged from the Steam Generator comes into a Flow Mixing Header Assembly (FMHA), and is rearranged and split into a very fine size. The FMHA is greatly important for enhancing the flow distribution of a downcomer during a normal operation, transient, and even accidents. Then, the fluid discharged from the FMHA flows into the core upstream through flow skirt holes. The Low Core Support Plate (LCSP) reallocates the flow introducing into the inlet core from the core upstream. The deviation of flow distribution becomes smaller or almost disappears by LCSP holes having relatively large loss coefficient compared to the downstream flow deviation. In an open core, the flow deviation at the core inlet region is diminished by cross flow as it goes upward. Near the core outlet, the flow distribution can be distorted by the influence of a Fuel Alignment Plate (FAP) installed above the fuels. In this paper, the effect of the core outlet flow structure such as the FAP holes of SMART is investigated. Before the calculation, the influences of mesh size and turbulence models are inspected. CFD simulations were performed to investigate the effect of FAP flow holes on the core outlet flow of SMART. As a preliminary study, the dependency of the mesh size and turbulence models was tested; a fine grid was applied, the effect of which is negligible, and the core outlet flow is not sensitive to the turbulence models. In brief, the flow resistance of FAP is less than 15% of that of the fuel assemblies. The flow resistance deviation between two flow path patterns is less than 1% of that of active core. Even two flow path patterns located at the downstream location of the

  10. CFD simulation on Kappel propeller with a hull wake field

    DEFF Research Database (Denmark)

    Shin, Keun Woo; Andersen, Poul; Møller Bering, Rasmus

    2013-01-01

    Marine propellers are designed not for the open-water operation, but for the operation behind a hull due to the inhomogeneous hull wake and thrust deduction. The adaptation for the hull wake is important for the propulsive efficiency and cavitation risk especially on single-screw ships. CFD...... simulations for a propeller with a hull model have showed acceptable agreement with a model test result in the thrust and torque (Larsson et al. 2010). In the current work, a measured hull wake is applied to the simulation instead of modelling a hull, because the hull geometry is mostly not available...... for propeller designers and the computational effort can be reduced by excluding the hull. The CFD simulation of a propeller flow with a hull wake is verified in order to use CFD as a propeller design tool. A Kappel propeller, which is an innovative tip-modified propeller, is handled. Kappel propellers...

  11. CFD analysis of ejector in a combined ejector cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Rusly, E.; Aye, Lu [International Technologies Centre (IDTC), Department of Civil and Environmental Engineering, The University of Melbourne, Melbourne, Vic. 3010 (Australia); Charters, W.W.S.; Ooi, A. [Department of Mechanical and Manufacturing Engineering, The University of Melbourne, Melbourne, Vic. 3010 (Australia)

    2005-11-01

    One-dimensional ejector analyses often use coefficients derived from experimental data for a set of operating conditions with limited functionality. In this study, several ejector designs were modelled using finite volume CFD techniques to resolve the flow dynamics in the ejectors. The CFD results were validated with available experimental data. Flow field analyses and predictions of ejector performance outside the experimental range were also carried out. During validation, data from CFD predicted the entrainment ratios with greater accuracy on definite area ratios, although no shock was recorded in the ejector. Predictions outside the experimental range-at operating conditions in a combined ejector-vapour compression system-and flow conditions resulting from ejector geometry variations are discussed. It is found that the maximum entrainment ratio happens in the ejector just before a shock occurs and that the position of the nozzle is an important ejector design parameter. (author)

  12. Partitioned Fluid-Structure Interaction for Full Rotor Computations Using CFD

    DEFF Research Database (Denmark)

    Heinz, Joachim Christian

    ) based aerodynamic model which is computationally cheap but includes several limitations and corrections in order to account for three-dimensional and unsteady eects. The present work discusses the development of an aero-elastic simulation tool where high-fidelity computational fluid dynamics (CFD......) is used to model the aerodynamics of the flexible wind turbine rotor. Respective CFD computations are computationally expensive but do not show the limitations of the BEM-based models. It is one of the first times that high-fidelity fluid-structure interaction (FSI) simulations are used to model the aero......-elastic response of an entire wind turbine rotor. The work employs a partitioned FSI coupling between the multi-body-based structural model of the aero-elastic solver HAWC2 and the finite volume CFD solver EllipSys3D. In order to establish an FSI coupling of sufficient time accuracy and sufficient numerical...

  13. CFD aspects of ADSS target design

    International Nuclear Information System (INIS)

    Shashi Kumar, G.N.; Mahendra, A.K.; Sanyal, A.; Gouthaman, G.

    2004-03-01

    The preliminary studies on CFD aspects of Accelerator Driven Sub-critical System (ADSS) target design has been presented in this report. The studies involve the thermal hydraulic analysis of the Liquid Metal Spallation Target (LMST) using Lead Bismuth Eutectic (LBE) as the target material. Apart from acting as Spallation medium LBE is used to remove the heat deposited by High Energy Proton Beam. Window of the target ( one side vacuum and other side LBE) has been reported in literature to be the most critical zone where high temperatures are reached. Numerical Simulations are carried out with Artificial Neural Network coupled Computational Fluid Dynamics (CFD) code, Various studies were carried out after the verification and validation of the initial results. Window being, the main parameter to be optimised, various designs of window were tried, along with change in the window material. The best possible combination has been proposed. The thermal hydraulic studies were carried out to arrive at the acceptable operating conditions for the target. (author)

  14. Prediction of subcooled flow boiling characteristics using two-fluid Eulerian CFD model

    Energy Technology Data Exchange (ETDEWEB)

    Braz Filho, Francisco A.; Ribeiro, Guilherme B., E-mail: gbribeiro@ieav.cta.br; Caldeira, Alexandre D.

    2016-11-15

    Highlights: • CFD multiphase model is used to predict subcooled flow boiling characteristics. • Better agreement is achieved for higher saturation pressures. • Onset of nucleate boiling and saturated boiling are well predicted. • CFD multiphase model tends to underestimate the void fraction. • Factors were adjusted in order to improve the void fraction results. - Abstract: The present study concerns a detailed analysis of flow boiling phenomena under high pressure systems using a two-fluid Eulerian approach provided by a Computational Fluid Dynamics (CFD) solver. For this purpose, a vertical heated pipe made of stainless steel with an internal diameter of 15.4 mm was considered as the modeled domain. Two different uniform heat fluxes and three saturation pressures were applied to the channel wall, whereas water mass flux of 900 kg/m{sup 2} s was considered for all simulation cases. The model was validated against a set of experimental data and results have indicated a promising use of the CFD technique for estimation of the wall temperature, the liquid bulk temperature and the location of the departure of nucleate boiling. Changes in factors applied in the modeling of the interfacial heat transfer coefficient and bubble departure frequency were suggested, allowing a better prediction of the void fraction along the heated channel. The commercial CFD solver FLUENT 14.5 was used for the model implementation.

  15. Prediction of subcooled flow boiling characteristics using two-fluid Eulerian CFD model

    International Nuclear Information System (INIS)

    Braz Filho, Francisco A.; Ribeiro, Guilherme B.; Caldeira, Alexandre D.

    2016-01-01

    Highlights: • CFD multiphase model is used to predict subcooled flow boiling characteristics. • Better agreement is achieved for higher saturation pressures. • Onset of nucleate boiling and saturated boiling are well predicted. • CFD multiphase model tends to underestimate the void fraction. • Factors were adjusted in order to improve the void fraction results. - Abstract: The present study concerns a detailed analysis of flow boiling phenomena under high pressure systems using a two-fluid Eulerian approach provided by a Computational Fluid Dynamics (CFD) solver. For this purpose, a vertical heated pipe made of stainless steel with an internal diameter of 15.4 mm was considered as the modeled domain. Two different uniform heat fluxes and three saturation pressures were applied to the channel wall, whereas water mass flux of 900 kg/m"2 s was considered for all simulation cases. The model was validated against a set of experimental data and results have indicated a promising use of the CFD technique for estimation of the wall temperature, the liquid bulk temperature and the location of the departure of nucleate boiling. Changes in factors applied in the modeling of the interfacial heat transfer coefficient and bubble departure frequency were suggested, allowing a better prediction of the void fraction along the heated channel. The commercial CFD solver FLUENT 14.5 was used for the model implementation.

  16. Drag Reduction CFD Simulations and Flow Visualization of Light Vehicle-Trailer Systems

    Science.gov (United States)

    Sigurdson, Lorenz; Boyer, Henry; Lange, Carlos F.

    2016-11-01

    Experiments and CFD were performed to study the effect a deflector had on the flow and drag force associated with a 2010 F-150 truck and cargo trailer Light Vehicle-Trailer System (LVTS). Image Correlation Velocimetry (ICV) on smokewire streaklines measured the velocity field on the model mid-plane. CFD estimated the drag reduction as 13% at a Re of 14,900 with a moving ground-plane, and 17% without. Experiments suggested that the low Re does not diminish the full-scale relevance of the drag reduction results. One low Re effect was the presence of a separation bubble on the hood of the tow vehicle whose size reduced with an increase in Re. Three other characteristic flow patterns were identified: separation off the lead vehicle cab, stagnation of the free-stream on the trailer face for the no-deflector case, and subsequent separation at the trailer front corner. Comparisons of the ICV and CFD results with no deflector indicated good agreement in the direction of the velocity vectors, and the smoke streaklines and CFD streamlines also agreed well. However, for the deflector case, the CFD found an entirely different topological solution absent in the experiment. A pair of vertically-oriented mid-plane vortices were wrapped around the front of the trailer. Support from the Canadian Natural Sciences and Engineering Research Council Grant 41747 is gratefully acknowledged.

  17. Analysis of Different Methods for Wave Generation and Absorption in a CFD-Based Numerical Wave Tank

    Directory of Open Access Journals (Sweden)

    Adria Moreno Miquel

    2018-06-01

    Full Text Available In this paper, the performance of different wave generation and absorption methods in computational fluid dynamics (CFD-based numerical wave tanks (NWTs is analyzed. The open-source CFD code REEF3D is used, which solves the Reynolds-averaged Navier–Stokes (RANS equations to simulate two-phase flow problems. The water surface is computed with the level set method (LSM, and turbulence is modeled with the k-ω model. The NWT includes different methods to generate and absorb waves: the relaxation method, the Dirichlet-type method and active wave absorption. A sensitivity analysis has been conducted in order to quantify and compare the differences in terms of absorption quality between these methods. A reflection analysis based on an arbitrary number of wave gauges has been adopted to conduct the study. Tests include reflection analysis of linear, second- and fifth-order Stokes waves, solitary waves, cnoidal waves and irregular waves generated in an NWT. Wave breaking over a sloping bed and wave forces on a vertical cylinder are calculated, and the influence of the reflections on the wave breaking location and the wave forces on the cylinder is investigated. In addition, a comparison with another open-source CFD code, OpenFOAM, has been carried out based on published results. Some differences in the calculated quantities depending on the wave generation and absorption method have been observed. The active wave absorption method is seen to be more efficient for long waves, whereas the relaxation method performs better for shorter waves. The relaxation method-based numerical beach generally results in lower reflected waves in the wave tank for most of the cases simulated in this study. The comparably better performance of the relaxation method comes at the cost of larger computational requirements due to the relaxation zones that have to be included in the domain. The reflections in the NWT in REEF3D are generally lower than the published results for

  18. Microcomputers, desk calculators and process computers for use in radiation protection

    International Nuclear Information System (INIS)

    Burgkhardt, B.; Nolte, G.; Schollmeier, W.; Rau, G.

    1983-01-01

    The goals achievable, or to be pursued, in radiation protection measurement and evaluation by using computers are explained. As there is a large variety of computers available offering a likewise large variety, of performances, use of a computer is justified even for minor measuring and evaluation tasks. The subdivision into: Microcomputers as an installed part of measuring equipment; measuring and evaluation systems with desk calculators; measuring and evaluation systems with process computers is done to explain the importance and extent of the measuring or evaluation tasks and the computing devices suitable for the various purposes. The special requirements to be met in order to fulfill the different tasks are discussed, both in terms of hardware and software and in terms of skill and knowledge of the personnel, and are illustrated by an example showing the usefulness of computers in radiation protection. (orig./HP) [de

  19. Status and outlook of CFD technology at Mitsubishi Heavy Industries, Nagoya

    Science.gov (United States)

    Tanioka, Tadayuki

    1990-09-01

    Computational Fluid Dynamics (CFD) technology has made tremendous progress in the last several years. It has matured to become a practical simulation tool in aircraft industries. In MHI, CFD has become an indispensible tool for aerodynamic design aerospace vehicles. The present status is described of this advanced technology at MHI. Also mentioned are some future advances of the fast growing technology as well as associated hardware requirements.

  20. A combined CFD-experimental method for developing an erosion equation for both gas-sand and liquid-sand flows

    Science.gov (United States)

    Mansouri, Amir

    The surface degradation of equipment due to consecutive impacts of abrasive particles carried by fluid flow is called solid particle erosion. Solid particle erosion occurs in many industries including oil and gas. In order to prevent abrupt failures and costly repairs, it is essential to predict the erosion rate and identify the locations of the equipment that are mostly at risk. Computational Fluid Dynamics (CFD) is a powerful tool for predicting the erosion rate. Erosion prediction using CFD analysis includes three steps: (1) obtaining flow solution, (2) particle tracking and calculating the particle impact speed and angle, and (3) relating the particle impact information to mass loss of material through an erosion equation. Erosion equations are commonly generated using dry impingement jet tests (sand-air), since the particle impact speed and angle are assumed not to deviate from conditions in the jet. However, in slurry flows, a wide range of particle impact speeds and angles are produced in a single slurry jet test with liquid and sand particles. In this study, a novel and combined CFD/experimental method for developing an erosion equation in slurry flows is presented. In this method, a CFD analysis is used to characterize the particle impact speed, angle, and impact rate at specific locations on the test sample. Then, the particle impact data are related to the measured erosion depth to achieve an erosion equation from submerged testing. Traditionally, it was assumed that the erosion equation developed based on gas testing can be used for both gas-sand and liquid-sand flows. The erosion equations developed in this work were implemented in a CFD code, and CFD predictions were validated for various test conditions. It was shown that the erosion equation developed based on slurry tests can significantly improve the local thickness loss prediction in slurry flows. Finally, a generalized erosion equation is proposed which can be used to predict the erosion rate in

  1. Moisture content evaluation of biomass using CFD approach

    Directory of Open Access Journals (Sweden)

    Thomas Bartzanas

    2012-10-01

    Full Text Available In grass conservation systems, drying in the field is an essential process upon which the quality and quantity of the material to be conserved is dependent on. In this study a Computational Fluid Dynamics (CFD model, previously validated, was used to assess qualitatively and quantitatively the field drying process of cut grass under different weather conditions and structural specifications of the grass. The use of the CFD model depicts the climate heterogeneity in the grass area with a special focus on moisture distribution, influence of the weather conditions, in order to create the possibility of applying the model as a decision support tool for an enhanced treatment of the grass after cutting.

  2. Comparison of DSMC and CFD Solutions of Fire II Including Radiative Heating

    Science.gov (United States)

    Liechty, Derek S.; Johnston, Christopher O.; Lewis, Mark J.

    2011-01-01

    The ability to compute rarefied, ionized hypersonic flows is becoming more important as missions such as Earth reentry, landing high mass payloads on Mars, and the exploration of the outer planets and their satellites are being considered. These flows may also contain significant radiative heating. To prepare for these missions, NASA is developing the capability to simulate rarefied, ionized flows and to then calculate the resulting radiative heating to the vehicle's surface. In this study, the DSMC codes DAC and DS2V are used to obtain charge-neutral ionization solutions. NASA s direct simulation Monte Carlo code DAC is currently being updated to include the ability to simulate charge-neutral ionized flows, take advantage of the recently introduced Quantum-Kinetic chemistry model, and to include electronic energy levels as an additional internal energy mode. The Fire II flight test is used in this study to assess these new capabilities. The 1634 second data point was chosen for comparisons to be made in order to include comparisons to computational fluid dynamics solutions. The Knudsen number at this point in time is such that the DSMC simulations are still tractable and the CFD computations are at the edge of what is considered valid. It is shown that there can be quite a bit of variability in the vibrational temperature inferred from DSMC solutions and that, from how radiative heating is computed, the electronic temperature is much better suited for radiative calculations. To include the radiative portion of heating, the flow-field solutions are post-processed by the non-equilibrium radiation code HARA. Acceptable agreement between CFD and DSMC flow field solutions is demonstrated and the progress of the updates to DAC, along with an appropriate radiative heating solution, are discussed. In addition, future plans to generate more high fidelity radiative heat transfer solutions are discussed.

  3. Scaling studies and conceptual experiment designs for NGNP CFD assessment

    Energy Technology Data Exchange (ETDEWEB)

    D. M. McEligot; G. E. McCreery

    2004-11-01

    The objective of this report is to document scaling studies and conceptual designs for flow and heat transfer experiments intended to assess CFD codes and their turbulence models proposed for application to prismatic NGNP concepts. The general approach of the project is to develop new benchmark experiments for assessment in parallel with CFD and coupled CFD/systems code calculations for the same geometry. Two aspects of the complex flow in an NGNP are being addressed: (1) flow and thermal mixing in the lower plenum ("hot streaking" issue) and (2) turbulence and resulting temperature distributions in reactor cooling channels ("hot channel" issue). Current prismatic NGNP concepts are being examined to identify their proposed flow conditions and geometries over the range from normal operation to decay heat removal in a pressurized cooldown. Approximate analyses have been applied to determine key non-dimensional parameters and their magnitudes over this operating range. For normal operation, the flow in the coolant channels can be considered to be dominant turbulent forced convection with slight transverse property variation. In a pressurized cooldown (LOFA) simulation, the flow quickly becomes laminar with some possible buoyancy influences. The flow in the lower plenum can locally be considered to be a situation of multiple hot jets into a confined crossflow -- with obstructions. Flow is expected to be turbulent with momentumdominated turbulent jets entering; buoyancy influences are estimated to be negligible in normal full power operation. Experiments are needed for the combined features of the lower plenum flows. Missing from the typical jet experiments available are interactions with nearby circular posts and with vertical posts in the vicinity of vertical walls - with near stagnant surroundings at one extreme and significant crossflow at the other. Two types of heat transfer experiments are being considered. One addresses the "hot channel" problem, if necessary

  4. CFD simulation and experimental validation of a GM type double inlet pulse tube refrigerator

    Science.gov (United States)

    Banjare, Y. P.; Sahoo, R. K.; Sarangi, S. K.

    2010-04-01

    Pulse tube refrigerator has the advantages of long life and low vibration over the conventional cryocoolers, such as GM and stirling coolers because of the absence of moving parts in low temperature. This paper performs a three-dimensional computational fluid dynamic (CFD) simulation of a GM type double inlet pulse tube refrigerator (DIPTR) vertically aligned, operating under a variety of thermal boundary conditions. A commercial computational fluid dynamics (CFD) software package, Fluent 6.1 is used to model the oscillating flow inside a pulse tube refrigerator. The simulation represents fully coupled systems operating in steady-periodic mode. The externally imposed boundary conditions are sinusoidal pressure inlet by user defined function at one end of the tube and constant temperature or heat flux boundaries at the external walls of the cold-end heat exchangers. The experimental method to evaluate the optimum parameters of DIPTR is difficult. On the other hand, developing a computer code for CFD analysis is equally complex. The objectives of the present investigations are to ascertain the suitability of CFD based commercial package, Fluent for study of energy and fluid flow in DIPTR and to validate the CFD simulation results with available experimental data. The general results, such as the cool down behaviours of the system, phase relation between mass flow rate and pressure at cold end, the temperature profile along the wall of the cooler and refrigeration load are presented for different boundary conditions of the system. The results confirm that CFD based Fluent simulations are capable of elucidating complex periodic processes in DIPTR. The results also show that there is an excellent agreement between CFD simulation results and experimental results.

  5. CFD simulations of steady flows over the IAR 65o delta wing

    International Nuclear Information System (INIS)

    Benmeddour, A.; Mebarki, Y.; Huang, X.Z.

    2004-01-01

    Computational Fluid Dynamics (CFD) studies have been conducted to simulate vortical flows around the IAR 65 o delta wing with a sharp leading edge. The effects of the centerbody on the aerodynamic characteristics of the wing are also investigated. Two flow solvers have been employed to compute steady inviscid flows over with and without centerbody configurations of the wing. These two solvers are an IAR in-house code, FJ3SOLV, and the CFD-FASTRAN commercial software. The computed flow solutions of the two solvers have been compared and correlated against the IAR wind tunnel data, including Pressure Sensitive Paint (PSP) measurements. The major features of the primary vortex have been well captured and overall reasonable accuracy was obtained. In accordance with the experimental observations for the flow conditions considered, the CFD computations revealed no major global effects of the centerbody on the surface pressure distributions of the wing and on the lift coefficient. However, CFD-FASTRAN seems to predict a vortex breakdown, which is neither predicted by FJ3SOLV nor observed in the wind tunnel for the flow conditions considered. (author)

  6. Present state and future of CFD based on three-dimensional RANS analysis

    International Nuclear Information System (INIS)

    Kim, Kwang Yong

    2004-01-01

    Computational Fluid Dynamics (CFD) based on Navier-Stokes equations has been developed rapidly for several decades with the developments of high speed computers and numerical algorithms, and presently is regarded as an essential analysis tool in the engineering applications containing fluid flow and convective heat transfer. It is known that for turbulent flow the Navier-Stokes equations can be calculated precisely by Direct Numerical Simulation (DNS). However, DNS needs huge computing time even for simple low-Reynolds number flows, and thus is not practical. Large Eddy Simulation (LES) can be an alternative. But, LES also needs considerable computing time for the analysis of engineering flows, and have some problem in the methods. Therefore, the analysis methods using Reynolds-averaged Navier-stokes equations (RANS) and turbulence closure models are still regarded as the major techniques for the analysis of turbulent flows in spite of the inaccuracy of the prediction. In this presentation, the present state and the prospect of CFD based on three-dimensional RANS analysis are introduced for physical models and numerical algorithms with the engineering examples. Especially, for the analysis of two-phase flows in nuclear reactor, the recently developed techniques are also introduced. And, the presentation includes the methods of design optimization using RANS analysis and numerical optimization techniques with variety of the applications

  7. Influence of Contact Angle Boundary Condition on CFD Simulation of T-Junction

    Science.gov (United States)

    Arias, S.; Montlaur, A.

    2018-03-01

    In this work, we study the influence of the contact angle boundary condition on 3D CFD simulations of the bubble generation process occurring in a capillary T-junction. Numerical simulations have been performed with the commercial Computational Fluid Dynamics solver ANSYS Fluent v15.0.7. Experimental results serve as a reference to validate numerical results for four independent parameters: the bubble generation frequency, volume, velocity and length. CFD simulations accurately reproduce experimental results both from qualitative and quantitative points of view. Numerical results are very sensitive to the gas-liquid-wall contact angle boundary conditions, confirming that this is a fundamental parameter to obtain accurate CFD results for simulations of this kind of problems.

  8. Extension of CFD Codes Application to Two-Phase Flow Safety Problems - Phase 3

    International Nuclear Information System (INIS)

    Bestion, D.; Anglart, H.; Mahaffy, J.; Lucas, D.; Song, C.H.; Scheuerer, M.; Zigh, G.; Andreani, M.; Kasahara, F.; Heitsch, M.; Komen, E.; Moretti, F.; Morii, T.; Muehlbauer, P.; Smith, B.L.; Watanabe, T.

    2014-11-01

    The Writing Group 3 on the extension of CFD to two-phase flow safety problems was formed following recommendations made at the 'Exploratory Meeting of Experts to Define an Action Plan on the Application of Computational Fluid Dynamics (CFD) Codes to Nuclear Reactor Safety Problems' held in Aix-en-Provence, in May 2002. Extension of CFD codes to two-phase flow is significant potentiality for the improvement of safety investigations, by giving some access to smaller scale flow processes which were not explicitly described by present tools. Using such tools as part of a safety demonstration may bring a better understanding of physical situations, more confidence in the results, and an estimation of safety margins. The increasing computer performance allows a more extensive use of 3D modelling of two-phase Thermal hydraulics with finer nodalization. However, models are not as mature as in single phase flow and a lot of work has still to be done on the physical modelling and numerical schemes in such two-phase CFD tools. The Writing Group listed and classified the NRS problems where extension of CFD to two-phase flow may bring real benefit, and classified different modelling approaches in a first report (Bestion et al., 2006). First ideas were reported about the specification and analysis of needs in terms of validation and verification. It was then suggested to focus further activity on a limited number of NRS issues with a high priority and a reasonable chance to be successful in a reasonable period of time. The WG3-step 2 was decided with the following objectives: - selection of a limited number of NRS issues having a high priority and for which two-phase CFD has a reasonable chance to be successful in a reasonable period of time; - identification of the remaining gaps in the existing approaches using two-phase CFD for each selected NRS issue; - review of the existing data base for validation of two-phase CFD application to the selected NRS problems

  9. CFD analysis of sludge accumulation and hydraulic performance of a waste stabilization pond.

    Science.gov (United States)

    Alvarado, Andres; Sanchez, Esteban; Durazno, Galo; Vesvikar, Mehul; Nopens, Ingmar

    2012-01-01

    Sludge management in waste stabilization ponds (WSPs) is essential for safeguarding the system performance. Sludge accumulation patterns in WSPs are strongly influenced by the pond hydrodynamics. CFD modeling was applied to study the relation between velocity profiles and sludge deposition during 10 years of operation of the Ucubamba WSP in Cuenca (Ecuador). One tracer experiment was performed and three sludge accumulation scenarios based on bathymetric surveys were simulated. A residence time distribution (RTD) analysis illustrated the decrease of residence times due to sludge deposition. Sludge accumulation rates were calculated. The influence of flow pattern on the sludge deposition was studied, enabling better planning of future pond operation and desludging.

  10. PENGARUH VARIASI BENTUK BURITAN KAPAL TERHADAP HAMBATAN TOTAL MENGGUNAKAN METODE CFD

    OpenAIRE

    Deddy Chrismianto; Berlian Arswendo Adietya

    2014-01-01

    Penelitian ini dilakukan dengan cara menganalisa dan menghitung hambatan total kapal menggunakan model 3D pada berbagai variasi bentuk buritan menggunakan CFD (Computational Fluid Dynamic).Berdasarkan hasil analisa dan perhitungan didapatkan hambatan total yang terkecil menggunakan CFD untuk berbagai variasi bentuk buritan kapal, dengan studi kasus pada type KCS (Kriso Container Ship). Hambatan total terkecil pada kondisi kecepatan fn 0.22 adalah 646.57 KN yaitu pada model 1, kemudian hambata...

  11. Pengaruh Variasi Bentuk Buritan Kapal Terhadap Hambatan Total Menggunakan Metode Cfd

    OpenAIRE

    Chrismianto, Deddy; Adietya, Berlian Arswendo

    2014-01-01

    Penelitian ini dilakukan dengan cara menganalisa dan menghitung hambatan total kapal menggunakan model 3D pada berbagai variasi bentuk buritan menggunakan CFD (Computational Fluid Dynamic).Berdasarkan hasil analisa dan perhitungan didapatkan hambatan total yang terkecil menggunakan CFD untuk berbagai variasi bentuk buritan kapal, dengan studi kasus pada type KCS (Kriso Container Ship). Hambatan total terkecil pada kondisi kecepatan fn 0.22 adalah 646.57 KN yaitu pada model 1, kemudian hambata...

  12. Investigation of piston bowl geometry and speed effects in a motored HSDI diesel engine using a CFD against a quasi-dimensional model

    International Nuclear Information System (INIS)

    Rakopoulos, C.D.; Kosmadakis, G.M.; Pariotis, E.G.

    2010-01-01

    The present work investigates the effect of varying the combustion chamber geometry and engine rotational speed on the gas flow and temperature field, using a new quasi-dimensional engine simulation model in conjunction with an in-house developed computational fluid dynamics (CFD) code served to validate the predicted in-cylinder flow field and gas temperature distribution calculated by the quasi-dimensional model, for three alternative piston bowl geometries and three rotational speeds. This CFD code can simulate three-dimensional curvilinear domains using the finite volume method in a collocated grid; it solves the generalized transport equation for the conservation of mass, momentum and energy, and incorporates the standard k-ε turbulence model with some slight modifications to introduce the compressibility of a fluid in generalized coordinates. On the other hand, the quasi-dimensional model solves the general transport equation for the conservation of mass and energy by a finite volume method throughout the entire in-cylinder volume, while for the estimation of the flow field a new simplified three dimensional air motion model is used. To compare these two models the in-cylinder spatial and temporal temperature distribution, the mean cylinder pressure diagram, as well as the mean in-cylinder radial and axial velocity are examined, for the three piston bowl geometries and the three speeds, for a high speed direct injection (HSDI) diesel engine operating under motoring conditions. From the comparison of calculated results, it becomes apparent that the two models predict similar in-cylinder temperature distributions and mean air velocity fields at each crank angle, for all cases examined. Thus, it is shown that the quasi-dimensional model with the proposed simplified air motion model is capable of capturing the physical effect of combustion chamber geometry and speed on the in-cylinder velocity and temperature field, while needing significantly lower computing

  13. Complex method to calculate objective assessments of information systems protection to improve expert assessments reliability

    Science.gov (United States)

    Abdenov, A. Zh; Trushin, V. A.; Abdenova, G. A.

    2018-01-01

    The paper considers the questions of filling the relevant SIEM nodes based on calculations of objective assessments in order to improve the reliability of subjective expert assessments. The proposed methodology is necessary for the most accurate security risk assessment of information systems. This technique is also intended for the purpose of establishing real-time operational information protection in the enterprise information systems. Risk calculations are based on objective estimates of the adverse events implementation probabilities, predictions of the damage magnitude from information security violations. Calculations of objective assessments are necessary to increase the reliability of the proposed expert assessments.

  14. CFD Investigation on Long-Haul Passenger Bus

    Science.gov (United States)

    Tan, C. F.; Tee, B. T.; Law, H. C.; Lim, T. L.

    2015-09-01

    Air flow distribution is one of the important factors that will influence the bus passenger comfort during long haul travel. Poor air flow distribution not only cause discomfort to the bus passenger but also influence their travel mode as well. The main purpose of this study is to investigate the air flow performance of the bus air-conditioning system through CFD simulation approach. A 3D CAD model of air ducts was drawn and hence analysed by using CFD software, namely ANSYS Fluent, to determine the airflow rate for every outlets of the air-conditioning system. The simulated result was then validated with experimental data obtained from prototype model of air duct. Based on the findings, new design concepts is proposed with the aim to meet the industry requirement as well as to improve the bus passenger comfort during long haul travel.

  15. URBAN EFFICIENT ENERGY EVALUATION IN HIGH RESOLUTION URBAN AREAS BY USING ADAPTED WRF-UCM AND MICROSYS CFD MODELS

    Science.gov (United States)

    San Jose, R.; Perez, J. L.; Gonzalez, R. M.

    2009-12-01

    Urban metabolism modeling has advanced substantially during the last years due to the increased detail in mesoscale urban parameterization in meteorological mesoscale models and CFD numerical tools. Recently the implementation of the “urban canopy model” (UCM) into the WRF mesoscale meteorological model has produced a substantial advance on the understanding of the urban atmospheric heat flux exchanges in the urban canopy. The need to optimize the use of heat energy in urban environment has produced a substantial increase in the detailed investigation of the urban heat flux exchanges. In this contribution we will show the performance of using a tool called MICROSYS (MICRO scale CFD modelling SYStem) which is an adaptation of the classical urban canopy model but on a high resolution environment by using a classical CFD approach. The energy balance in the urban system can be determined in a micrometeorologicl sense by considering the energy flows in and out of a control volume. For such a control volume reaching from ground to a certain height above buildings, the energy balance equation includes the net radiation, the anthropogenic heat flux, the turbulent sensible heat flux, the turbulent latent heat flux, the net storage change within the control volume, the net advected flux and other sources and sinks. We have applied the MICROSYS model to an area of 5 km x 5 km with 200 m spatial resolution by using the WRF-UCM (adapted and the MICROSYS CFD model. The anthropogenic heat flux has been estimated by using the Flanner M.G. (2009) database and detailed GIS information (50 m resolution) of Madrid city. The Storage energy has been estimated by calculating the energy balance according to the UCM procedure and implementing it into the MICROSYS tool. Results show that MICROSYS can be used as an energy efficient tool to estimate the energy balance of different urban areas and buildings.

  16. Simulation of single-phase rod bundle flow. Comparison between CFD-code ESTET, PWR core code THYC and experimental results

    International Nuclear Information System (INIS)

    Mur, J.; Larrauri, D.

    1998-07-01

    Computer simulation of flow in configurations close to pressurized water reactor (PWR) geometry is of great interest for Electricite de France (EDF). Although simulation of the flow through a whole PWR core with an all purpose CFD-code is not yet achievable, such a tool cna be quite useful to perform numerical experiments in order to try and improve the modeling introduced in computer codes devoted to reactor core thermal-hydraulic analysis. Further to simulation in small bare rod bundle configurations, the present study is focused on the simulation, with CFD-code ESTET and PWR core code THYC, of the flow in the experimental configuration VATICAN-1. ESTET simulation results are compared on the one hand to local velocity and concentration measurements, on the other hand with subchannel averaged values calculated by THYC. As far as the comparison with measurements is concerned, ESTET results are quite satisfactory relatively to available experimental data and their uncertainties. The effect of spacer grids and the prediction of the evolution of an unbalanced velocity profile seem to be correctly treated. As far as the comparison with THYC subchannel averaged values is concerned, the difficulty of a direct comparison between subchannel averaged and local values is pointed out. ESTET calculated local values are close to experimental local values. ESTET subchannel averaged values are also close to THYC calculation results. Thus, THYC results are satisfactory whereas their direct comparison to local measurements could show some disagreement. (author)

  17. Carotid DSA based CFD simulation in assessing the patient with asymptomatic carotid stenosis: a preliminary study.

    Science.gov (United States)

    Zhang, Dong; Xu, Pengcheng; Qiao, Hongyu; Liu, Xin; Luo, Liangping; Huang, Wenhua; Zhang, Heye; Shi, Changzheng

    2018-03-12

    Cerebrovascular events are frequently associated with hemodynamic disturbance caused by internal carotid artery (ICA) stenosis. It is challenging to determine the ischemia-related carotid stenosis during the intervention only using digital subtracted angiography (DSA). Inspired by the performance of well-established FFRct technique in hemodynamic assessment of significant coronary stenosis, we introduced a pressure-based carotid arterial functional assessment (CAFA) index generated from computational fluid dynamic (CFD) simulation in DSA data, and investigated its feasibility in the assessment of hemodynamic disturbance preliminarily using pressure-wired measurement and arterial spin labeling (ASL) MRI as references. The cerebral multi-delay multi-parametric ASL-MRI and carotid DSA including trans-stenotic pressure-wired measurement were implemented on a 65-year-old man with asymptomatic unilateral (left) ICA stenosis. A CFD simulation using simplified boundary condition was performed in DSA data to calculate the CAFA index. The cerebral blood flow (CBF) and arterial transit time (ATT) of ICA territories were acquired. CFD simulation showed good correlation (r = 0.839, P = 0.001) with slight systematic overestimation (mean difference - 0.007, standard deviation 0.017) compared with pressure-wired measurement. No significant difference was observed between them (P = 0.09). Though the narrowing degree of in the involved ICA was about 70%, the simulated and measured CAFA (0.942/0.937) revealed a functionally nonsignificant stenosis which was also verified by a compensatory final CBF (fronto-temporal/fronto-parietal region: 51.58/45.62 ml/100 g/min) and slightly prolonged ATT (1.23/1.4 s) in the involved territories, together with a normal left-right percentage difference (2.1-8.85%). The DSA based CFD simulation showed good consistence with invasive approach and could be used as a cost-saving and efficient way to study the relationship between

  18. Experimental PIV and CFD studies of UV-peroxide advanced oxidation reactors for water treatment

    International Nuclear Information System (INIS)

    Sozzi, A.; Taghipour, F.

    2004-01-01

    An experimental and numerical study of the flow characteristics in an annular UV reactor, as used for drinking water disinfection or Advanced Oxidation Processes, was carried out using Particle Image Velocimetry (PIV) and Computational Fluid Dynamics (CFD). The influence of different turbulence models and mesh structures on the CFD results was investigated. By qualitative and quantitative comparison of CFD and PIV experimental data, it was shown that the Realizable k-e- turbulence model is best suited for simulating the hydrodynamics of this geometry. (author)

  19. An overview of past and present CFD activities within the framework of WGAMA

    International Nuclear Information System (INIS)

    Smith, B.L.; Mahaffy, J.H.; Bestion, D.; Zigh, G.

    2011-01-01

    In 2003, three Writing Groups (WG1, WG2, WG3) were established within the Working Group on Analysis and Management of Accidents (WGAMA) of the OECD Nuclear Energy Agency. The groups had the responsibility of summarising the state-of-the-art in the application of Computational Fluid Dynamics (CFD) to items of concern in nuclear reactor safety. The Best Practice Guidelines (BPGs) drawn up by the WG1 group defined the procedures which need to be followed to produce trustworthy results from a CFD simulation. The WG2 group itemised the assessment base which underpins single-phase CFD as an established technology. The WG3 group focused on the challenges that still need to be faced before two-phase CFD may be regarded as a mature science. The background to the activity, method of approach, documented evidence, status and current activities are described under appropriate section headings in this paper. (author)

  20. 3D CFD Quantification of the Performance of a Multi-Megawatt Wind Turbine

    Science.gov (United States)

    Laursen, J.; Enevoldsen, P.; Hjort, S.

    2007-07-01

    This paper presents the results of 3D CFD rotor computations of a Siemens SWT-2.3-93 variable speed wind turbine with 45m blades. In the paper CFD is applied to a rotor at stationary wind conditions without wind shear, using the commercial multi-purpose CFD-solvers ANSYS CFX 10.0 and 11.0. When comparing modelled mechanical effects with findings from other models and measurements, good agreement is obtained. Similarly the computed force distributions compare very well, whereas some discrepancies are found when comparing with an in-house BEM model. By applying the reduced axial velocity method the local angle of attack has been derived from the CFD solutions, and from this knowledge and the computed force distributions, local airfoil profile coefficients have been computed and compared to BEM airfoil coefficients. Finally, the transition model of Langtry and Menter is tested on the rotor, and the results are compared with the results from the fully turbulent setup.

  1. 3D CFD Quantification of the Performance of a Multi-Megawatt Wind Turbine

    International Nuclear Information System (INIS)

    Laursen, J; Enevoldsen, P; Hjort, S

    2007-01-01

    This paper presents the results of 3D CFD rotor computations of a Siemens SWT-2.3-93 variable speed wind turbine with 45m blades. In the paper CFD is applied to a rotor at stationary wind conditions without wind shear, using the commercial multi-purpose CFD-solvers ANSYS CFX 10.0 and 11.0. When comparing modelled mechanical effects with findings from other models and measurements, good agreement is obtained. Similarly the computed force distributions compare very well, whereas some discrepancies are found when comparing with an in-house BEM model. By applying the reduced axial velocity method the local angle of attack has been derived from the CFD solutions, and from this knowledge and the computed force distributions, local airfoil profile coefficients have been computed and compared to BEM airfoil coefficients. Finally, the transition model of Langtry and Menter is tested on the rotor, and the results are compared with the results from the fully turbulent setup

  2. Assessment of CFD capability for prediction of hypersonic shock interactions

    Science.gov (United States)

    Knight, Doyle; Longo, José; Drikakis, Dimitris; Gaitonde, Datta; Lani, Andrea; Nompelis, Ioannis; Reimann, Bodo; Walpot, Louis

    2012-01-01

    The aerothermodynamic loadings associated with shock wave boundary layer interactions (shock interactions) must be carefully considered in the design of hypersonic air vehicles. The capability of Computational Fluid Dynamics (CFD) software to accurately predict hypersonic shock wave laminar boundary layer interactions is examined. A series of independent computations performed by researchers in the US and Europe are presented for two generic configurations (double cone and cylinder) and compared with experimental data. The results illustrate the current capabilities and limitations of modern CFD methods for these flows.

  3. Managing Uncertainty in Runoff Estimation with the U.S. Environmental Protection Agency National Stormwater Calculator.

    Science.gov (United States)

    The U.S. Environmental Protection Agency National Stormwater Calculator (NSWC) simplifies the task of estimating runoff through a straightforward simulation process based on the EPA Stormwater Management Model. The NSWC accesses localized climate and soil hydrology data, and opti...

  4. CFD analysis of the temperature field in emergency pump room in Loviisa NPP

    Energy Technology Data Exchange (ETDEWEB)

    Rämä, Tommi, E-mail: tommi.rama@fortum.com [Fortum Power and Heat, P.O.B. 100, FI-00048 Fortum (Finland); Toppila, Timo, E-mail: timo.toppila@fortum.com [Fortum Power and Heat, P.O.B. 100, FI-00048 Fortum (Finland); Kelavirta, Teemu, E-mail: teemu.kelavirta@fortum.com [Fortum Power and Heat, Loviisa Power Plant, P.O.B. 23, FI-07901 Loviisa (Finland); Martin, Pasi, E-mail: pasi.martin@fortum.com [Fortum Power and Heat, Loviisa Power Plant, P.O.B. 23, FI-07901 Loviisa (Finland)

    2014-11-15

    Highlights: • Laser scanned room geometry from Loviisa NPP was utilized for CFD simulation. • Uncertainty of CFD simulation was estimated using the Grid Convergence Index. • Measured temperature field of pump room was reproduced with CFD simulation. - Abstract: In the Loviisa Nuclear Power Plant (NPP) six emergency pumps belonging to the same redundancy are located in the same room. During a postulated accident the cooling of the room is needed as the engines of the emergency pumps generate heat. Cooling is performed with fans blowing air to the upper part of the room. Temperature limits have been given to the operating conditions of the main components in order to ensure their reliable operation. Therefore the temperature field of the room is important to know. Temperature measurements were made close to the most important components of the pump room to get a better understanding of the temperature field. For these measurements emergency pumps and cooling fan units were activated. To simulate conditions during a postulated accident additional warm-air heaters were used. Computational fluid dynamic (CFD) simulations were made to support plant measurements. For the CFD study one of the pump rooms of Loviisa NPP was scanned with a laser and this data converted to detailed 3-D geometry. Tetrahedral computation grid was created inside the geometry. Grid sensitivity studies were made, and the model was then validated against the power plant tests. With CFD the detailed temperature and flow fields of the whole room were produced. The used CFD model was able to reproduce the temperature field of the measurements. Two postulated accident cases were simulated. In the cases the operating cooling units were varied. The temperature profile of the room changes significantly depending on which units are cooling and which only circulating the air. The room average temperature stays approximately the same. The simulation results were used to ensure the acceptable operating

  5. Verification Results of Safety-grade Optical Modem for Core Protection Calculator (CPC) in Korea Standard Nuclear Power Plant (KSNP)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jangyeol; Son, Kwangseop; Lee, Youngjun; Cheon, Sewoo; Cha, Kyoungho; Lee, Jangsoo; Kwon, Keechoon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    We confirmed that the coverage criteria for a safety-grade optical modem of a Core Protection Calculator is satisfactory using a traceability analysis matrix between high-level requirements and lower-level system test case data set. This paper describes the test environment, test components and items, a traceability analysis, and system tests as a result of system verification and validation based on Software Requirement Specifications (SRS) for a safety-grade optical modem of a Core Protection Calculator (CPC) in a Korea Standard Nuclear Power Plant (KSNP), and Software Design Specifications (SDS) for a safety-grade optical modem of a CPC in a KSNP. All tests were performed according to the test plan and test procedures. Functional testing, performance testing, event testing, and scenario based testing for a safety-grade optical modem of a Core Protection Calculator in a Korea Standard Nuclear Power Plant as a thirty-party verifier were successfully performed.

  6. CFD flowfield simulation of Delta Launch Vehicles in a power-on configuration

    Science.gov (United States)

    Pavish, D. L.; Gielda, T. P.; Soni, B. K.; Deese, J. E.; Agarwal, R. K.

    1993-01-01

    This paper summarizes recent work at McDonnell Douglas Aerospace (MDA) to develop and validate computational fluid dynamic (CFD) simulations of under expanded rocket plume external flowfields for multibody expendable launch vehicles (ELVs). Multi engine reacting gas flowfield predictions of ELV base pressures are needed to define vehicle base drag and base heating rates for sizing external nozzle and base region insulation thicknesses. Previous ELV design programs used expensive multibody power-on wind tunnel tests that employed chamber/nozzle injected high pressure cold or hot-air. Base heating and pressure measurements were belatedly made during the first flights of past ELV's to correct estimates from semi-empirical engineering models or scale model tests. Presently, CFD methods for use in ELV design are being jointly developed at the Space Transportation Division (MDA-STD) and New Aircraft Missiles Division (MDA-NAMD). An explicit three dimensional, zonal, finite-volume, full Navier-Stokes (FNS) solver with finite rate hydrocarbon/air and aluminum combustion kinetics was developed to accurately compute ELV power-on flowfields. Mississippi State University's GENIE++ general purpose interactive grid generation code was chosen to create zonal, finite volume viscous grids. Axisymmetric, time dependent, turbulent CFD simulations of a Delta DSV-2A vehicle with a MB-3 liquid main engine burning RJ-1/LOX were first completed. Hydrocarbon chemical kinetics and a k-epsilon turbulence model were employed and predictions were validated with flight measurements of base pressure and temperature. Zonal internal/external grids were created for a Delta DSV-2C vehicle with a MB-3 and three Castor-1 solid motors burning and a Delta-2 with an RS-27 main engine (LOX/RP-1) and 9 GEM's attached/6 burning. Cold air, time dependent FNS calculations were performed for DSV-2C during 1992. Single phase simulations that employ finite rate hydrocarbon and aluminum (solid fuel) combustion

  7. Aplicação de CFD para o cálculo de coeficientes de pressão externos nas aberturas de um edifício = Application of CFD simulations for the calculation of external wind pressure coefficients on openings of a building

    NARCIS (Netherlands)

    Cóstola, D.; Alucci, M.P.

    2011-01-01

    Pressure coefficients (Cp) are a key parameter in the study of wind-driven natural ventilation in buildings. This paper reports the results of a research study aimed at evaluating the feasility of using CFD (Computational Fluid Dynamics) to obtain Cp data and also evaluating the importance of some

  8. Computational Fluid Dynamics (CFD) investigation onto passenger car disk brake design

    Science.gov (United States)

    Munisamy, Kannan M.; Kanasan Moorthy, Shangkari K.

    2013-06-01

    The aim of this study is to investigate the flow and heat transfer in ventilated disc brakes using Computational Fluid Dynamics (CFD). NACA Series blade is designed for ventilated disc brake and the cooling characteristic is compared to the baseline design. The ventilated disc brakes are simulated using commercial CFD software FLUENTTM using simulation configuration that was obtained from experiment data. The NACA Series blade design shows improvements in Nusselt number compared to baseline design.

  9. Toward a CFD-grade database addressing LWR containment phenomena

    International Nuclear Information System (INIS)

    Paladino, Domenico; Andreani, Michele; Zboray, Robert; Dreier, Jörg

    2012-01-01

    Highlights: ► The SETH-2 PANDA tests have supplied data with CFD-grade on plumes and jets at large-scale. ► The PANDA tests have contributed to the understanding of phenomena with high safety relevance for LWRs. ► The analytical activities related increased confidence in the use of various computational tools for safety analysis. - Abstract: The large-scale, multi-compartment PANDA facility (located at PSI in Switzerland) is one of the state-of-the-art facilities which is continuously upgraded to progressively match the requirements of CFD-grade experiments. Within the OECD/SETH projects, the PANDA facility has been used for the creation of an experimental database on basic containment phenomena e.g. gas mixing, transport, stratification, condensation. In the PANDA tests, these phenomena are driven by large scale plumes or jets. In the paper is presented a selection of the SETH PANDA experimental results. Examples of analytical activities performed at PSI using the GOTHIC, CFX-4 and CFX-5 codes will be used to illustrate how the spatial and temporal resolutions of the measurement grid in PANDA tests are adequate for CFD code (and advanced containment codes) assessment and validation purposes.

  10. Investigations of Fluid-Structure-Coupling and Turbulence Model Effects on the DLR Results of the Fifth AIAA CFD Drag Prediction Workshop

    Science.gov (United States)

    Keye, Stefan; Togiti, Vamish; Eisfeld, Bernhard; Brodersen, Olaf P.; Rivers, Melissa B.

    2013-01-01

    The accurate calculation of aerodynamic forces and moments is of significant importance during the design phase of an aircraft. Reynolds-averaged Navier-Stokes (RANS) based Computational Fluid Dynamics (CFD) has been strongly developed over the last two decades regarding robustness, efficiency, and capabilities for aerodynamically complex configurations. Incremental aerodynamic coefficients of different designs can be calculated with an acceptable reliability at the cruise design point of transonic aircraft for non-separated flows. But regarding absolute values as well as increments at off-design significant challenges still exist to compute aerodynamic data and the underlying flow physics with the accuracy required. In addition to drag, pitching moments are difficult to predict because small deviations of the pressure distributions, e.g. due to neglecting wing bending and twisting caused by the aerodynamic loads can result in large discrepancies compared to experimental data. Flow separations that start to develop at off-design conditions, e.g. in corner-flows, at trailing edges, or shock induced, can have a strong impact on the predictions of aerodynamic coefficients too. Based on these challenges faced by the CFD community a working group of the AIAA Applied Aerodynamics Technical Committee initiated in 2001 the CFD Drag Prediction Workshop (DPW) series resulting in five international workshops. The results of the participants and the committee are summarized in more than 120 papers. The latest, fifth workshop took place in June 2012 in conjunction with the 30th AIAA Applied Aerodynamics Conference. The results in this paper will evaluate the influence of static aeroelastic wing deformations onto pressure distributions and overall aerodynamic coefficients based on the NASA finite element structural model and the common grids.

  11. CFD simulations of compressed air two stage rotary Wankel expander – Parametric analysis

    International Nuclear Information System (INIS)

    Sadiq, Ghada A.; Tozer, Gavin; Al-Dadah, Raya; Mahmoud, Saad

    2017-01-01

    Highlights: • CFD ANSYS-Fluent 3D simulation of Wankel expander is developed. • Single and two-stage expander’s performance is compared. • Inlet and outlet ports shape and configurations are investigated. • Isentropic efficiency of two stage Wankel expander of 91% is achieved. - Abstract: A small scale volumetric Wankel expander is a powerful device for small-scale power generation in compressed air energy storage (CAES) systems and Organic Rankine cycles powered by different heat sources such as, biomass, low temperature geothermal, solar and waste heat leading to significant reduction in CO_2 emissions. Wankel expanders outperform other types of expander due to their ability to produce two power pulses per revolution per chamber additional to higher compactness, lower noise and vibration and lower cost. In this paper, a computational fluid dynamics (CFD) model was developed using ANSYS 16.2 to simulate the flow dynamics for a single and two stage Wankel expanders and to investigate the effect of port configurations, including size and spacing, on the expander’s power output and isentropic efficiency. Also, single-stage and two-stage expanders were analysed with different operating conditions. Single-stage 3D CFD results were compared to published work showing close agreement. The CFD modelling was used to investigate the performance of the rotary device using air as an ideal gas with various port diameters ranging from 15 mm to 50 mm; port spacing varying from 28 mm to 66 mm; different Wankel expander sizes (r = 48, e = 6.6, b = 32) mm and (r = 58, e = 8, b = 40) mm both as single-stage and as two-stage expanders with different configurations and various operating conditions. Results showed that the best Wankel expander design for a single-stage was (r = 48, e = 6.6, b = 32) mm, with the port diameters 20 mm and port spacing equal to 50 mm. Moreover, combining two Wankel expanders horizontally, with a larger one at front, produced 8.52 kW compared

  12. Development of CFD software for the simulation of thermal hydraulics in advanced nuclear reactors. Final report

    International Nuclear Information System (INIS)

    Bachar, Abdelaziz; Haslinger, Wolfgang; Scheuerer, Georg; Theodoridis, Georgios

    2015-01-01

    The objectives of the project were: Improvement of the simulation accuracy for nuclear reactor thermo-hydraulics by coupling system codes with three-dimensional CFD software; Extension of CFD software to predict thermo-hydraulics in advanced reactor concepts; Validation of the CFD software by simulation different UPTF TRAM-C test cases and development of best practice guidelines. The CFD module was based on the ANSYS CFD software and the system code ATHLET of GRS. All three objectives were met: The coupled ATHLET-ANSYS CFD software is in use at GRS and TU Muenchen. Besides the test cases described in the report, it has been used for other applications, for instance the TALL-3D experiment of KTH Stockholm. The CFD software was extended with material properties for liquid metals, and validated using existing data. Several new concepts were tested when applying the CFD software to the UPTF test cases: Simulations with Conjugate Heat Transfer (CHT) were performed for the first time. This led to better agreement between predictions and data and reduced uncertainties when applying temperature boundary conditions. The meshes for the CHT simulation were also used for a coupled fluid-structure-thermal analysis which was another novelty. The results of the multi-physics analysis showed plausible results for the mechanical and thermal stresses. The workflow developed as part of the current project can be directly used for industrial nuclear reactor simulations. Finally, simulations for two-phase flows with and without interfacial mass transfer were performed. These showed good agreement with data. However, a persisting problem for the simulation of multi-phase flows are the long simulation times which make use for industrial applications difficult.

  13. CFD simulation on critical heat flux of flow boiling in IVR-ERVC of a nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiang, E-mail: zhangxiang3@snptc.com.cn [State Nuclear Power Technology Research & Development Center, South Area, Future Science and Technology Park, Chang Ping District, Beijing 102209 (China); Hu, Teng [State Nuclear Power Technology Research & Development Center, South Area, Future Science and Technology Park, Chang Ping District, Beijing 102209 (China); Chen, Deqi, E-mail: chendeqi@cqu.edu.cn [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, 400044 (China); Zhong, Yunke; Gao, Hong [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, 400044 (China)

    2016-08-01

    Highlights: • CFD simulation on CHF of boiling two-phase flow in ERVC is proposed. • CFD simulation result of CHF agrees well with that of experimental result. • The characteristics of boiling two-phase flow and boiling crisis are analyzed. - Abstract: The effectiveness of in-vessel retention (IVR) by external reactor vessel cooling (ERVC) strongly depends on the critical heat flux (CHF). As long as the local CHF does not exceed the local heat flux, the lower head of the pressure vessel can be cooled sufficiently to prevent from failure. In this paper, a CFD simulation is carried out to investigate the CHF of ERVC. This simulation is performed by a CFD code fluent couple with a boiling model by UDF (User-Defined Function). The experimental CHF of ERVC obtained by State Nuclear Power Technology Research and Development Center (SNPTRD) is used to validate this CFD simulation, and it is found that the simulation result agrees well with the experimental result. Based on the CFD simulation, detailed analysis focusing on the pressure distribution, velocity distribution, void fraction distribution, heating wall temperature distribution are proposed in this paper.

  14. CFD aided approach to design printed circuit heat exchangers for supercritical CO2 Brayton cycle application

    International Nuclear Information System (INIS)

    Kim, Seong Gu; Lee, Youho; Ahn, Yoonhan; Lee, Jeong Ik

    2016-01-01

    Highlights: • CFD analyses were performed to find performance of PCHE for supercritical CO 2 power cycle. • CFD results were obtained beyond the limits of existing correlations. • Designs of different PCHEs with different correlations were compared. • A new CFD-aided correlation covering a wider Reynolds number range was proposed. - Abstract: While most conventional PCHE designs for working fluid of supercritical CO 2 require an extension of valid Reynolds number limits of experimentally obtained correlations, Computational Fluid Dynamics (CFD) code ANSYS CFX was used to explore validity of existing correlations beyond their tested Reynolds number ranges. For heat transfer coefficient correlations, an appropriate piece-wising with Ishizuka’s and Hesselgreaves’s correlation is found to enable an extension of Reynolds numbers. For friction factors, no single existing correlation is found to capture different temperature and angular dependencies for a wide Reynolds number range. Based on the comparison of CFD results with the experimentally obtained correlations, a new CFD-aided correlation covering an extended range of Reynolds number 2000–58,000 for Nusselt number and friction factor is proposed to facilitate PCHE designs for the supercritical CO 2 Brayton cycle application.

  15. Mixing and RTD in tanks: radiotracer experiments and CFD simulations

    International Nuclear Information System (INIS)

    Thatte, A.R.; Patwardhan, A.P.; Pant, H.J.; Sharma, V.K.; Gursharan Singh; Berne, Ph.

    2004-01-01

    The present work is directed towards exploring the possibility of developing a model for predicting the residence time distribution based on the actual flow and turbulence fields present within the reactor. In view of this, experiments have been carried out to characterize mixing processes in two different equipment: jet mixer and stirred tank reactor. CFD models have been developed to predict the mixing time and residence time distribution in these equipments. In all the case, it is observed that the CFD predictions agree well with the experimental measurements. (author)

  16. Mass conservative fluid flow visualization for CFD velocity fields

    International Nuclear Information System (INIS)

    Li, Zhenquan; Mallinson, Gordon D.

    2001-01-01

    Mass conservation is a key issue for accurate streamline and stream surface visualization of flow fields. This paper complements an existing method (Feng et al., 1997) for CFD velocity fields defined at discrete locations in space that uses dual stream functions to generate streamlines and stream surfaces. Conditions for using the method have been examined and its limitations defined. A complete set of dual stream functions for all possible cases of the linear fields on which the method relies are presented. The results in this paper are important for developing new methods for mass conservative streamline visualization from CFD data and using the existing method

  17. CFD analysis on mixing effects of spacer grids with different dimples and sizes for advanced fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Yang, B.W.; Zhang, H.; Han, B.; Zha, Y.D.; Shan, J.Q. [Xi' an Jiaotong Univ. (China). School of Nuclear Science and Technology

    2016-07-15

    The thermal hydraulic characteristics of a mixing vane grid are largely dependent on the structure of key components, such as strip, spring, dimple, weld nugget, as well as the mixing vane configuration. In this paper, several types of spacer grids with different dimple shapes are modeled under subcooled boiling conditions. Prior to the application of CFD on the dimple shape analysis, the mixing effects of spacer grids were studied. After the dimple shape analysis, the side channel effect is discussed by comparing the simulation results of a 3 x 3 and a 5 x 5 spacer grid. The two phase flow CFD models in this study are validated through simple geometry showing that the calculated void fraction is in good agreement with the experimental data. The dimple comparison result shows that varying dimple structures can result in different temperatures, lateral velocities and void fraction distributions downstream of the spacer grids. Comparison of two sizes of spacer grids demonstrate that the side channel generates different flow distribution pattern in the center channel.

  18. Summary of best guidelines and validation of CFD modeling in livestock buildings to ensure prediction quality

    DEFF Research Database (Denmark)

    Rong, Li; Nielsen, Peter Vilhelm; Bjerg, Bjarne Schmidt

    2016-01-01

    scale pig barns was simulated to show the procedures of validating a CFD simulation in livestock buildings. After summarizing the guideline and/or best practice for CFD modeling, the authors addressed the issues related to numerical methods and the governing equations, which were limited to RANS models....... Although it is not necessary to maintain the same format of reporting the CFD modeling as presented in this paper, the authors would suggest including all the information related to the selection of turbulence models, difference schemes, convergence criteria, boundary conditions, geometry simplification......, simulating domain etc. This information is particularly important for the readers to evaluate the quality of the CFD simulation results....

  19. CFD Analyses for Water-Air Flow With the Euler-Euler Two-Phase Model in the Fluent4 CFD Code

    International Nuclear Information System (INIS)

    Miettinen, Jaakko; Schmidt, Holger

    2002-01-01

    calculation results were adjusted for a good agreement with the experimental data. The analysis results were very valuable for designing the final water/steam facility for final CHF tests. The validation against data from the air-water experiments proved that the present CFD codes approach to the state where they can be used for simulating such two-phase experiments, where the fraction of both phases is essential and the flow is strongly affected by the density differences. It is still too early to predict, if the CFD calculation of the 1:1 scale critical heat flux experiments is successful, could the result be used for formulating a new type of a critical heat flux correlation, where the effects of CRD's on the flow patterns and gap dimensions are model parameters. (authors)

  20. Calculations to an IAHR-benchmark test using the CFD-code CFX-4

    Energy Technology Data Exchange (ETDEWEB)

    Krepper, E

    1998-10-01

    The calculation concerns a test, which was defined as a benchmark for 3-D codes by the working group of advanced nuclear reactor types of IAHR (International Association of Hydraulic Research). The test is well documented and detailed measuring results are available. The test aims at the investigation of phenomena, which are important for heat removal at natural circulation conditions in a nuclear reactor. The task for the calculation was the modelling of the forced flow field of a single phase incompressible fluid with consideration of heat transfer and influence of gravity. These phenomena are typical also for other industrial processes. The importance of correct modelling of these phenomena also for other applications is a motivation for performing these calculations. (orig.)

  1. Simulation of steady-state natural convection using CFD

    Energy Technology Data Exchange (ETDEWEB)

    Zitzmann, T.; Pfrommer, P. [Univ. of Applied Sciences, Coberg (Germany); Cook, M.; Rees, S.; Marjanovic, L. [De Montfort Univ., Leicester (United Kingdom). Inst. of Energy and Sustainable Development

    2005-07-01

    Building materials play an important role in the creation of comfortable indoor environments and can reduce dependence on high energy use mechanical systems. Correct predictions between building structure and heat transfer are needed in order to achieve optimal conditions. Heat transfer is dependent on the velocity and temperature distribution in a room, particularly in the wall boundary layer. This paper discussed the modeling of air flow and heat transfer over a heated vertical plate in a differentially-heated cavity using Computational Fluid Dynamics (CFD). Guidelines on the use of CFD with unstructured meshes to model buoyancy-driven flow in a cavity were presented. Benchmark CFD results were compared with published analytical data. The finite volume method was employed using an unstructured mesh containing tetrahedral and prism elements, so that local numerical diffusion was reduced and therefore suitable for complex flows. The code was based on a couple solver for solving the differential equations using the fully implicit discretization method. Hydrodynamic equations were treated as one single system. A false time stepping method was used to reduce the number of iterations required for convergence, which also guided the solutions to a steady-state solution. It was concluded that the methodology achieves accurate predictions, and is suitable for the modeling of heat transfer optimizations. 13 refs., 7 figs.

  2. CFD Simulations of a Single-phase Mixing Experiment

    International Nuclear Information System (INIS)

    Bertolotto, Davide; Chawla, Rakesh; Manera, Annalisa; Prasser, Horst-Michael

    2008-01-01

    The current paper reports on an investigation of the capabilities of CFD codes to model multidimensional mixing phenomena in a loop. For the purpose, a test facility consisting of two loops connected by a double T-junction has been built at the Paul Scherrer Institut (PSI). Experiments were carried out, in which a tracer was injected in one loop and the tracer distribution before and after the T-junction was measured by means of wire-mesh sensors located at the outlets of the junction. The tracer distribution after the T-junction is strongly dependent on 3D mixing phenomena, which are dominant due to the particular geometry of the set-up. For the CFD analysis, a 3D model of the double T-junction was created, and different simulations were performed with ANSYS-CFX to study the sensitivity of the results with respect to parameters such as mesh refinement, integration time step, turbulence model, profiles for inlet velocity and injected tracer concentration. Thereafter, these results were compared with the experimental data. The comparisons have clearly pointed out that 3D modelling is able to reproduce (at least qualitatively) the experimental results. Moreover, it has been found that the CFD results are strongly influenced by the velocity profile assumptions at the inlets of the double T-junction. (authors)

  3. A CFD model for pollutant dispersion in rivers

    Directory of Open Access Journals (Sweden)

    Modenesi K.

    2004-01-01

    Full Text Available Studies have shown that humankind will experience a water shortage in the coming decades. It is therefore paramount to develop new techniques and models with a view to minimizing the impact of pollution. It is important to predict the environmental impact of new emissions in rivers, especially during periods of drought. Computational fluid dynamics (CFD has proved to be an invaluable tool to develop models able to analyze in detail particle dispersion in rivers. However, since these models generate grids with thousands (even millions of points to evaluate velocities and concentrations, they still require powerful machines. In this context, this work contributes by presenting a new three-dimensional model based on CFD techniques specifically developed to be fast, providing a significant improvement in performance. It is able to generate predictions in a couple of hours for a one-thousand-meter long section of river using Pentium IV computers. Commercial CFD packages would require weeks to solve the same problem. Another innovation inb this work is that a half channel with a constant elliptical cross section represents the river, so the Navier Stokes equations were derived for the elliptical system. Experimental data were obtained from REPLAN (PETROBRAS refining unit on the Atibaia River in São Paulo, Brazil. The results show good agreement with experimental data.

  4. Computational Fluid Dynamics (CFD) investigation onto passenger car disk brake design

    International Nuclear Information System (INIS)

    Munisamy, Kannan M; Moorthy, Shangkari K Kanasan

    2013-01-01

    The aim of this study is to investigate the flow and heat transfer in ventilated disc brakes using Computational Fluid Dynamics (CFD). NACA Series blade is designed for ventilated disc brake and the cooling characteristic is compared to the baseline design. The ventilated disc brakes are simulated using commercial CFD software FLUENT TM using simulation configuration that was obtained from experiment data. The NACA Series blade design shows improvements in Nusselt number compared to baseline design.

  5. An overview of CFD and PIV application in investigation of solar thermal systems

    DEFF Research Database (Denmark)

    Ai, Ning; Fan, Jianhua; Ji, Jianbing

    2007-01-01

    . The most promising solution to this challenge is the use of computational fluid dynamics (CFD) in combination with particle image velocimetry (PIV),which will be the future trend in the investigation of solar thermal systems. The aim of this work is to give an overview of the status of the CFD...

  6. Calculation of Radiation Protection Quantities and Analysis of Astronaut Orientation Dependence

    Science.gov (United States)

    Clowdsley, Martha S.; Nealy, John E.; Atwell, William; Anderson, Brooke M.; Luetke, Nathan J.; Wilson, John W.

    2006-01-01

    Health risk to astronauts due to exposure to ionizing radiation is a primary concern for exploration missions and may become the limiting factor for long duration missions. Methodologies for evaluating this risk in terms of radiation protection quantities such as dose, dose equivalent, gray equivalent, and effective dose are described. Environment models (galactic cosmic ray and solar particle event), vehicle/habitat geometry models, human geometry models, and transport codes are discussed and sample calculations for possible lunar and Mars missions are used as demonstrations. The dependence of astronaut health risk, in terms of dosimetric quantities, on astronaut orientation within a habitat is also examined. Previous work using a space station type module exposed to a proton spectrum modeling the October 1989 solar particle event showed that reorienting the astronaut within the module could change the calculated dose equivalent by a factor of two or more. Here the dose equivalent to various body tissues and the whole body effective dose due to both galactic cosmic rays and a solar particle event are calculated for a male astronaut in two different orientations, vertical and horizontal, in a representative lunar habitat. These calculations also show that the dose equivalent at some body locations resulting from a solar particle event can vary by a factor of two or more, but that the dose equivalent due to galactic cosmic rays has a much smaller (<15%) dependence on astronaut orientation.

  7. Development of a compartment model based on CFD simulations for description of mixing in bioreactors

    Directory of Open Access Journals (Sweden)

    Crine, M.

    2010-01-01

    Full Text Available Understanding and modeling the complex interactions between biological reaction and hydrodynamics are a key problem when dealing with bioprocesses. It is fundamental to be able to accurately predict the hydrodynamics behavior of bioreactors of different size and its interaction with the biological reaction. CFD can provide detailed modeling about hydrodynamics and mixing. However, it is computationally intensive, especially when reactions are taken into account. Another way to predict hydrodynamics is the use of "Compartment" or "Multi-zone" models which are much less demanding in computation time than CFD. However, compartments and fluxes between them are often defined by considering global quantities not representative of the flow. To overcome the limitations of these two methods, a solution is to combine compartment modeling and CFD simulations. Therefore, the aim of this study is to develop a methodology in order to propose a compartment model based on CFD simulations of a bioreactor. The flow rate between two compartments can be easily computed from the velocity fields obtained by CFD. The difficulty lies in the definition of the zones in such a way they can be considered as perfectly mixed. The creation of the model compartments from CFD cells can be achieved manually or automatically. The manual zoning consists in aggregating CFD cells according to the user's wish. The automatic zoning defines compartments as regions within which the value of one or several properties are uniform with respect to a given tolerance. Both manual and automatic zoning methods have been developed and compared by simulating the mixing of an inert scalar. For the automatic zoning, several algorithms and different flow properties have been tested as criteria for the compartment creation.

  8. Investigation of effective thermal conductivity for pebble beds by one-way coupled CFD-DEM method for CFETR WCCB

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lei [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui 230027 (China); Chen, Youhua [University of Science and Technology of China, Hefei, Anhui 230027 (China); Huang, Kai [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Liu, Songlin, E-mail: slliu@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui 230027 (China)

    2016-05-15

    Highlights: • A CFD-DEM coupled numerical model is built based on the prototypical blanket pebble bed. • The numerical model can be applied to simulate heat transfer of a pebble bed and estimate effective thermal conductivity. • The numerical model agrees well with the theoretical SZB model. • Effective thermal conductivity of pebble beds for WCCB is estimated by the current model. - Abstract: The mono-sized beryllium pebble bed and the multi-sized Li{sub 2}TiO{sub 3}/Be{sub 12}Ti mixed pebble bed are the main schemes for the Water-cooled ceramic breeder blanket (WCCB) of China Fusion Engineering Test Reactor (CFETR). And the effective thermal conductivity (k{sub eff}) of the pebble beds is important to characterize the thermal performance of WCCB. In this study, a one-way coupled CFD-DEM method was employed to simulate heat transfer and estimate k{sub eff}. The geometric topology of a prototypical blanket pebble bed was produced by the discrete element method (DEM). Based on the geometric topology, the temperature distribution and the k{sub eff} were obtained by the computational fluid dynamics (CFD) analysis. The current numerical model presented a good performance to calculate k{sub eff} of the beryllium pebble bed, and according to the modeling of the Li{sub 2}TiO{sub 3}/Be{sub 12}Ti mixed pebble bed, k{sub eff} was estimated with values ranged between 2.0 and 4.0 W/(m∙K).

  9. Integrating Multibody Simulation and CFD: toward Complex Multidisciplinary Design Optimization

    Science.gov (United States)

    Pieri, Stefano; Poloni, Carlo; Mühlmeier, Martin

    This paper describes the use of integrated multidisciplinary analysis and optimization of a race car model on a predefined circuit. The objective is the definition of the most efficient geometric configuration that can guarantee the lowest lap time. In order to carry out this study it has been necessary to interface the design optimization software modeFRONTIER with the following softwares: CATIA v5, a three dimensional CAD software, used for the definition of the parametric geometry; A.D.A.M.S./Motorsport, a multi-body dynamic simulation software; IcemCFD, a mesh generator, for the automatic generation of the CFD grid; CFX, a Navier-Stokes code, for the fluid-dynamic forces prediction. The process integration gives the possibility to compute, for each geometrical configuration, a set of aerodynamic coefficients that are then used in the multiboby simulation for the computation of the lap time. Finally an automatic optimization procedure is started and the lap-time minimized. The whole process is executed on a Linux cluster running CFD simulations in parallel.

  10. radEq Add-On Module for CFD Solver Loci-CHEM

    Science.gov (United States)

    McCloud, Peter

    2013-01-01

    Loci-CHEM to be applied to flow velocities where surface radiation due to heating from compression and friction becomes significant. The module adds a radiation equilibrium boundary condition to the computational fluid dynamics (CFD) code to produce accurate results. The module expanded the upper limit for accurate CFD solutions of Loci-CHEM from Mach 4 to Mach 10 based on Space Shuttle Orbiter Re-Entry trajectories. Loci-CHEM already has a very promising architecture and performance, but absence of radiation equilibrium boundary condition limited the application of Loci-CHEM to below Mach 4. The immediate advantage of the add-on module is that it allows Loci-CHEM to work with supersonic flows up to Mach 10. This transformed Loci-CHEM from a rocket engine- heritage CFD code with general subsonic and low-supersonic applications, to an aeroheating code with hypersonic applications. The follow-on advantage of the module is that it is a building block for additional add-on modules that will solve for the heating generated at Mach numbers higher than 10.

  11. Velocities in a Centrifugal PAT Operation: Experiments and CFD Analyses

    Directory of Open Access Journals (Sweden)

    Mariana Simão

    2017-12-01

    Full Text Available Velocity profiles originated by a pump as turbine (PAT were measured using an ultrasonic doppler velocimetry (UDV. PAT behavior is influenced by the velocity data. The effect of the rotational speed and the associated flow velocity variations were investigated. This research focuses, particularly, on the velocity profiles achieved for different rotational speeds and discharge values along the impeller since that is where the available hydraulic power is transformed into the mechanical power. Comparisons were made between experimental test results and computational fluid dynamics (CFD simulations. The used CFD model was calibrated and validated using the same conditions as the experimental facility. The numerical simulations showed good approximation with the velocity measurements for different cross-sections along the PAT system. The application of this CFD numerical model and experimental tests contributed to better understanding the system behavior and to reach the best efficiency operating conditions. Improvements in the knowledge about the hydrodynamic flow behavior associated with the velocity triangles contribute to improvements in the PAT concept and operation.

  12. CFD simulation of transient stage of continuous countercurrent hydrolysis of canola oil

    KAUST Repository

    Wang, Weicheng

    2012-08-01

    Computational Fluid Dynamic (CFD) modeling of a continuous countercurrent hydrolysis process was performed using ANSYS-CFX. The liquid properties and flow behavior such as density, specific heats, dynamic viscosity, thermal conductivity, and thermal expansivity as well as water solubility of the hydrolysis components triglyceride, diglyceride, monoglyceride, free fatty acid, and glycerol were calculated. Chemical kinetics for the hydrolysis reactions were simulated in this model by applying Arrhenius parameters. The simulation was based on actual experimental reaction conditions including temperature and water-to-oil ratio. The results not only have good agreement with experimental data but also show instantaneous distributions of concentrations of every component in hydrolysis reaction. This model provided visible insight into the continuous countercurrent hydrolysis process. © 2012 Elsevier Ltd.

  13. CFD simulation of transient stage of continuous countercurrent hydrolysis of canola oil

    KAUST Repository

    Wang, Weicheng; Natelson, Robert H.; Stikeleather, Larry F.; Roberts, William L.

    2012-01-01

    Computational Fluid Dynamic (CFD) modeling of a continuous countercurrent hydrolysis process was performed using ANSYS-CFX. The liquid properties and flow behavior such as density, specific heats, dynamic viscosity, thermal conductivity, and thermal expansivity as well as water solubility of the hydrolysis components triglyceride, diglyceride, monoglyceride, free fatty acid, and glycerol were calculated. Chemical kinetics for the hydrolysis reactions were simulated in this model by applying Arrhenius parameters. The simulation was based on actual experimental reaction conditions including temperature and water-to-oil ratio. The results not only have good agreement with experimental data but also show instantaneous distributions of concentrations of every component in hydrolysis reaction. This model provided visible insight into the continuous countercurrent hydrolysis process. © 2012 Elsevier Ltd.

  14. CFD simulation of neutral ABL flows; Atmospheric Boundary Layer

    Energy Technology Data Exchange (ETDEWEB)

    Xiaodong Zhang

    2009-04-15

    This work is to evaluate the CFD prediction of Atmospheric Boundary Layer flow field over different terrains employing Fluent 6.3 software. How accurate the simulation could achieve depend on following aspects: viscous model, wall functions, agreement of CFD model with inlet wind velocity profile and top boundary condition. Fluent employ wall function roughness modifications based on data from experiments with sand grain roughened pipes and channels, describe wall adjacent zone with Roughness Height (Ks) instead of Roughness Length (z{sub 0}). In a CFD simulation of ABL flow, the mean wind velocity profile is generally described with either a logarithmic equation by the presence of aerodynamic roughness length z{sub 0} or an exponential equation by the presence of exponent. As indicated by some former researchers, the disagreement between wall function model and ABL velocity profile description will result in some undesirable gradient along flow direction. There are some methods to improve the simulation model in literatures, some of them are discussed in this report, but none of those remedial methods are perfect to eliminate the streamwise gradients in mean wind speed and turbulence, as EllipSys3D could do. In this paper, a new near wall treatment function is designed, which, in some degree, can correct the horizontal gradients problem. Based on the corrected model constants and near wall treatment function, a simulation of Askervein Hill is carried out. The wind condition is neutrally stratified ABL and the measurements are best documented until now. Comparison with measured data shows that the CFD model can well predict the velocity field and relative turbulence kinetic energy field. Furthermore, a series of artificial complex terrains are designed, and some of the main simulation results are reported. (au)

  15. CFD modelling of condensers for freeze-drying processes

    Indian Academy of Sciences (India)

    Freeze-drying; condenser; CFD simulation; mathematical modelling; ... it is used for the stabilization and storage of delicate, heat-sensitive materials .... The effect of the surface mass transfer has been included in the continuity equation and.

  16. The status of research on CFD-PBM simulation of liquid-liquid two-phase flow in extraction columns

    International Nuclear Information System (INIS)

    Li Shaowei; Jing Shan; Wu Qiulin; Zhang Qi

    2012-01-01

    Computational fluid dynamics (CFD) simulation has gained more and more interest in the chemical engineering researchers and is becoming a useful tool for the chemical engineering research. The research on liquid-liquid two-phase flow CFD simulation in extraction columns is now in its initial stage. There is much work to do for the developing of this research field. The purpose of this article is to review the CFD simulation methods for two-phase flow in extraction column. The population balance model (PBM) is detailedly described in this article because it is the main method used in the two-phase flow CFD simulation currently. Then some examples for the two-phase flow simulation in extraction columns are briefly introduced. The strategy for the research on CFD simulation of two-phase flow in extraction columns is suggested at last. (authors)

  17. Multiphase flow in porous media using CFD

    DEFF Research Database (Denmark)

    Hemmingsen, Casper Schytte; Walther, Jens Honore

    . This approach is widely used for single phase flow, but not for multiphase flow in porous media. This might be due to the complexity of introducing relative permeability and capillary pressure in the CFD solver.The introduction of relative permeability and capillary pressure may cause numerical instabilities...

  18. Numerical CFD Comparison of Lillgrund Employing RANS

    DEFF Research Database (Denmark)

    Simisiroglou, N.; Breton, S.-P.; Crasto, G.

    2014-01-01

    The following article will validate the results obtained using the actuator disc method in the state of the art numerical Computational Fluid Dynamic (CFD) tool WindSim using on-site measurements from the offshore wind farm Lillgrund. WindSim solves the mass, momentum and energy conservation...

  19. Computational fluid dynamics (CFD) assisted performance evaluation of the Twincer™ disposable high-dose dry powder inhaler.

    Science.gov (United States)

    de Boer, Anne H; Hagedoorn, Paul; Woolhouse, Robert; Wynn, Ed

    2012-09-01

    To use computational fluid dynamics (CFD) for evaluating and understanding the performance of the high-dose disposable Twincer™ dry powder inhaler, as well as to learn the effect of design modifications on dose entrainment, powder dispersion and retention behaviour. Comparison of predicted flow and particle behaviour from CFD computations with experimental data obtained with cascade impactor and laser diffraction analysis. Inhaler resistance, flow split, particle trajectories and particle residence times can well be predicted with CFD for a multiple classifier based inhaler like the Twincer™. CFD computations showed that the flow split of the Twincer™ is independent of the pressure drop across the inhaler and that the total flow rate can be decreased without affecting the dispersion efficacy or retention behaviour. They also showed that classifier symmetry can be improved by reducing the resistance of one of the classifier bypass channels, which for the current concept does not contribute to the swirl in the classifier chamber. CFD is a highly valuable tool for development and optimisation of dry powder inhalers. CFD can assist adapting the inhaler design to specific physico-chemical properties of the drug formulation with respect to dispersion and retention behaviour. © 2012 The Authors. JPP © 2012 Royal Pharmaceutical Society.

  20. Application of an atmospheric CFD code to wind resource assessment in complex terrain

    International Nuclear Information System (INIS)

    Laporte, Laurent

    2008-01-01

    This thesis is organized in two parts. The first part presents the use of the atmospheric CFD code Mercure Saturne to estimate the wind resource in complex terrain. A measurement campaign was led by EDF to obtain data for validation. A methodology was developed using meso-scale profiles as boundary conditions. Clustering of meteorological situations was used to reduce the number of simulations needed to calculate the wind resource. The validation of the code on the Askervein hill, the methodology and comparisons with measurements from the complex site are presented. The second part presents the modeling of wakes with the Mercure Saturne code. Forces, generated by the blades on the wind, are modeled by source terms, calculated by the BEM method. Two comparisons are proposed to validate the method: the first compares the numerical model with wind tunnel measurements from a small wind turbine, the second with measurements made on porous disks in an atmospheric boundary layer wind tunnel (author) [fr

  1. Development Of An Experiment For Measuring Flow Phenomena Occurring In A Lower Plenum For VHTR CFD Assessment

    Energy Technology Data Exchange (ETDEWEB)

    D. M. McEligot; K.G. Condie; G. E. Mc Creery; H. M. Mc Ilroy

    2005-09-01

    The objective of the present report is to document the design of our first experiment to measure generic flow phenomena expected to occur in the lower plenum of a typical prismatic VHTR (Very High Temperature Reactor) concept. In the process, fabrication sketches are provided for the use of CFD (computational fluid dynamics) analysts wishing to employ the data for assessment of their proposed codes. The general approach of the project is to develop new benchmark experiments for assessment in parallel with CFD and coupled CFD/systems code calculations for the same geometry. One aspect of the complex flow in a prismatic VHTR is being addressed: flow and thermal mixing in the lower plenum ("hot streaking" issue). Current prismatic VHTR concepts were examined to identify their proposed flow conditions and geometries over the range from normal operation to decay heat removal in a pressurized cooldown. Approximate analyses were applied to determine key non-dimensional parameters and their magnitudes over this operating range. The flow in the lower plenum can locally be considered to be a situation of multiple jets into a confined crossflow -- with obstructions. Flow is expected to be turbulent with momentum-dominated turbulent jets entering; buoyancy influences are estimated to be negligible in normal full power operation. Experiments are needed for the combined features of the lower plenum flows. Missing from the typical jet experiments available are interactions with nearby circular posts and with vertical posts in the vicinity of vertical walls - with near stagnant surroundings at one extreme and significant crossflow at the other.

  2. A turbulence model for large interfaces in high Reynolds two-phase CFD

    International Nuclear Information System (INIS)

    Coste, P.; Laviéville, J.

    2015-01-01

    Highlights: • Two-phase CFD commonly involves interfaces much larger than the computational cells. • A two-phase turbulence model is developed to better take them into account. • It solves k–epsilon transport equations in each phase. • The special treatments and transfer terms at large interfaces are described. • Validation cases are presented. - Abstract: A model for two-phase (six-equation) CFD modelling of turbulence is presented, for the regions of the flow where the liquid–gas interface takes place on length scales which are much larger than the typical computational cell size. In the other regions of the flow, the liquid or gas volume fractions range from 0 to 1. Heat and mass transfer, compressibility of the fluids, are included in the system, which is used at high Reynolds numbers in large scale industrial calculations. In this context, a model based on k and ε transport equations in each phase was chosen. The paper describes the model, with a focus on the large interfaces, which require special treatments and transfer terms between the phases, including some approaches inspired from wall functions. The validation of the model is based on high Reynolds number experiments with turbulent quantities measurements of a liquid jet impinging a free surface and an air water stratified flow. A steam–water stratified condensing flow experiment is also used for an indirect validation in the case of heat and mass transfer

  3. Overview of Computational Fluid Dynamics (CFD) simulation of stirred vessel

    International Nuclear Information System (INIS)

    Mohd Rizal Mamat; Azraf Azman; Anwar Abdul Rahman; Noraishah Othman

    2010-01-01

    Stirred vessel is one of many widely used equipment in industrial process and chemical industry. The design of stirred vessel typically follows a certain standard chemical engineering practice that may also involve empirical data acquired from experiments. However the design may still take a different route which is computational engineering simulation and analysis. CFD has been identified as one of the possible tools for such purposes. CFD enables the flow fields variables such as velocity, temperature and pressure in the whole computational domain to be obtained and as such it presents an advantage over the experimental setup. (author)

  4. Validation of CFD modeling for VGM loss-of-forced-cooling accidents

    International Nuclear Information System (INIS)

    Wysocki, Aaron; Ahmed, Bobby; Charmeau, Anne; Anghaie, Samim

    2009-01-01

    Heat transfer and fluid flow in the VGM reactor cavity cooling system (RCCS) was modeled using Computational Fluid Dynamics (CFD). The VGM is a Russian modular-type high temperature helium-cooled reactor. In the reactor cavity, heat is removed from the pressure vessel wall through natural convection and radiative heat transfer to water-cooled vertical pipes lining the outer cavity concrete. The RCCS heat removal capability under normal operation and accident scenarios needs to be assessed. The purpose of the present study is to validate the use of CFD to model heat transfer in the VGM RCCS. Calculations were based on a benchmark problem which defines a two-dimensional temperature distribution on the pressure vessel outer wall for both Depressurized and Pressurized Loss-of-Forced Cooling events. A two-dimensional axisymmetric model was developed to determine the best numerical modeling approach. A grid sensitivity study for the air region showed that a 20 mm mesh size with a boundary layer giving a maximum y+ of 2.0 was optimal. Sensitivity analyses determined that the discrete ordinates radiative model, the k-omega turbulence model, and the ideal gas law gave the best combination for capturing radiation and natural circulation in the air cavity. A maximum RCCS pipe wall temperature of 62degC located 6 m from the top of the cavity was predicted. The model showed good agreement with previous results for both Pressurized and Depressurized Loss-of-Forced-Cooling accidents based on RCCS coolant outlet temperature, relative contributions of radiative and convective heat transfer, and RCCS heat load profiles. (author)

  5. On the use of a CFD software for reactor design support

    International Nuclear Information System (INIS)

    Garcia, J.C.; Rauschert, A.; Coleff, Agustin

    2009-01-01

    Different analysis performed with CFD software for reactor design support are shown. The CFD software used was FLUENT version 6.3.26. The first analysis corresponds to an MTR-type reactor. The MTR-type reactor core is constituted by plate fuel elements. The cooling water passes through channels formed by fuel plates with gap between 2 and 4 mm. The flow between two plates uniformly heated was modeled. The results obtained with FLUENT were compared with experimental data, for a transition Reynolds number. The subchannel with nonuniform power in the plates was modeled with those turbulence models which were closer to experimental results. The second analysis corresponds to an integrated PWR type reactor. The downcomer was modeled in order to visualize the streamlines and velocity distribution. Since the complete model of the downcomer would involve a large number of cells, thereby increasing the computation time, one twelfth of the same is modeled due to the symmetry of the problem. The third analysis also corresponds to an integrated PWR type reactor. The transition into the downcomer at the loss of the cold source was modeled. Since the complete model of the downcomer would involve a large number of cells, thereby increasing the computation time, one twenty fourth of the same is modeled due to the symmetry of the problem. A variable flow and temperature in the downcomer inlet were used as boundary condition. With this calculation, we can visualize the time distribution of velocities and temperatures in one of the symmetry planes. (author)

  6. CFD optimization of continuous stirred-tank (CSTR) reactor for biohydrogen production.

    Science.gov (United States)

    Ding, Jie; Wang, Xu; Zhou, Xue-Fei; Ren, Nan-Qi; Guo, Wan-Qian

    2010-09-01

    There has been little work on the optimal configuration of biohydrogen production reactors. This paper describes three-dimensional computational fluid dynamics (CFD) simulations of gas-liquid flow in a laboratory-scale continuous stirred-tank reactor used for biohydrogen production. To evaluate the role of hydrodynamics in reactor design and optimize the reactor configuration, an optimized impeller design has been constructed and validated with CFD simulations of the normal and optimized impeller over a range of speeds and the numerical results were also validated by examination of residence time distribution. By integrating the CFD simulation with an ethanol-type fermentation process experiment, it was shown that impellers with different type and speed generated different flow patterns, and hence offered different efficiencies for biohydrogen production. The hydrodynamic behavior of the optimized impeller at speeds between 50 and 70 rev/min is most suited for economical biohydrogen production. Copyright 2010 Elsevier Ltd. All rights reserved.

  7. Preliminary CFD analysis methodology for flow in a LFR fuel assembly

    International Nuclear Information System (INIS)

    Catana, A.; Ioan, M.; Serbanel, M.

    2013-01-01

    In this paper a preliminary Computational Fluid Dynamics (CFD) analysis was performed in order to setup a methodology to be used for more complex coolant flow analysis inside ALFRED nuclear reactor fuel assembly. The core contains 171 separated fuel assembly, each consisting in a hexagonal array of 127 fuel rods. Three honey comb spacer grids are proposed along fuel rods with the aim to keep flow geometry intact during reactor operation. The main goal of this paper is to compute some hydraulic parameters: pressure, velocity, wall shear stress and turbulence parameters with and without spacer grids. In this analysis we consider an adiabatic case, so far no heat transfer is considered but we pave the road toward more complex thermo hydraulic analysis for ALFRED (LFR in general). The CAELINUX CFD distribution was used with its main components: Salome-Meca (for geometry and mesh) and Code-Saturne as mono-phase CFD solver. Paraview and Visist Postprocessors were used for data extraction and graphical displays. (authors)

  8. Calculations of hydrogen transport for the simulation of a Sbo in the NPP-L V using the code CFD GASFLOW; Calculos de transporte de hidrogeno para la simulacion de un SBO en la CNLV usando el codigo CFD GASFLOW

    Energy Technology Data Exchange (ETDEWEB)

    Gomez T, A. M.; Xolocostli M, V. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Lopez M, R.; Filio L, C.; Mugica R, C. A. [Comision Nacional de Seguridad Nuclear y Salvaguardias, Dr. Jose Ma. Barragan No. 779, Col. Narvarte, 03020 Mexico D. F. (Mexico); Royl, P., E-mail: armando.gomez@inin.gob.mx [Karlsruhe Institute of Technology, Consultor, Hermann-von-Helmholtz-Platz, D-76344 Eggenstein -Leopoldshafen, Karlsruhe (Germany)

    2013-10-15

    The scenario of electric power total loss in the nuclear power plant of Laguna Verde (NPP-L V) has been analyzed using the code MELCOR previously, until reaching fault conditions of the primary container. A mitigation measure to avoid the loss of the primary contention is the realization of a venting toward the secondary contention (reactor building), however this measure bears the potential explosions occurrence risk when the hydrogen accumulated in the primary container with the oxygen of the reactor building atmosphere reacting. In this work a scenario has been supposed that considers the mentioned venting when the pressure of 4.5 kg/cm{sup 2} is reached in the primary container. The information for the hydrogen like an entrance fact is obtained of the MELCOR results and the hydrogen transport in both contentions is analyzed with the code CFD GASFLOW that allows predicting the detailed distribution of the hydrogen volumetric concentration and the possible detonation of flammability conditions in the reactor building. The results show that the venting will produce detonation conditions in the venting level (level 33) and flammability in the level of the recharge floor. The methodology here described constitutes the base of a detailed calculation system of this type of phenomena that can use to make safety evaluations in the NPP-L V on scenarios that include gases transport. (Author)

  9. X-37 separation from a B-52H: application of multi-body dynamics and closed-loop feedback using overset CFD

    International Nuclear Information System (INIS)

    Jolly, B.; Rizk, M.; Moran, R.

    2005-01-01

    The Air Force SEEK EAGLE Office (AFSEO) provided independent aerodynamic data, which was key in the separation analysis for the X-37 Approach and Landing Test Vehicle (ALTV). To ensure the best aerodynamic B-52H interference database would be generated for the analysis, NASA contracted both NASA Johnson Space Center (JSC) and the AFSEO via the 412th Flight Test Squadron (Edwards AFB CA) to run independent Computational Fluid Dynamics (CFD) studies. These data were then compared to the existing database from Boeing to establish confidence and determine areas of uncertainty. NASA requested CFD data from the AFSEO primarily for static and carriage solutions of the X-37 at various positions under the B-52H. In addition, several dynamic simulations of X-37 trajectories used rate feedback control to deflect the control surfaces to stabilize the X-37. The AFSEO CFD team calculated 140 static, unsteady solutions and 9 dynamic time-accurate trajectory simulations between April 2003 and June 2004 to support the NASA X-37 ALTV program. The computational models used structured adjacent and overlapping grids with the total computational domain consisting of 25 million points in 315 grids. The rate-control autopilot commanded both yaw and roll in four control surfaces; pitch commands were preset. The results show significant increase in stability of the X-37 trajectory from the B-52H. (author)

  10. High-accuracy CFD prediction methods for fluid and structure temperature fluctuations at T-junction for thermal fatigue evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Shaoxiang, E-mail: qian.shaoxiang@jgc.com [EN Technology Center, Process Technology Division, JGC Corporation, 2-3-1 Minato Mirai, Nishi-ku, Yokohama 220-6001 (Japan); Kanamaru, Shinichiro [EN Technology Center, Process Technology Division, JGC Corporation, 2-3-1 Minato Mirai, Nishi-ku, Yokohama 220-6001 (Japan); Kasahara, Naoto [Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2015-07-15

    Highlights: • Numerical methods for accurate prediction of thermal loading were proposed. • Predicted fluid temperature fluctuation (FTF) intensity is close to the experiment. • Predicted structure temperature fluctuation (STF) range is close to the experiment. • Predicted peak frequencies of FTF and STF also agree well with the experiment. • CFD results show the proposed numerical methods are of sufficiently high accuracy. - Abstract: Temperature fluctuations generated by the mixing of hot and cold fluids at a T-junction, which is widely used in nuclear power and process plants, can cause thermal fatigue failure. The conventional methods for evaluating thermal fatigue tend to provide insufficient accuracy, because they were developed based on limited experimental data and a simplified one-dimensional finite element analysis (FEA). CFD/FEA coupling analysis is expected as a useful tool for the more accurate evaluation of thermal fatigue. The present paper aims to verify the accuracy of proposed numerical methods of simulating fluid and structure temperature fluctuations at a T-junction for thermal fatigue evaluation. The dynamic Smagorinsky model (DSM) is used for large eddy simulation (LES) sub-grid scale (SGS) turbulence model, and a hybrid scheme (HS) is adopted for the calculation of convective terms in the governing equations. Also, heat transfer between fluid and structure is calculated directly through thermal conduction by creating a mesh with near wall resolution (NWR) by allocating grid points within the thermal boundary sub-layer. The simulation results show that the distribution of fluid temperature fluctuation intensity and the range of structure temperature fluctuation are remarkably close to the experimental results. Moreover, the peak frequencies of power spectrum density (PSD) of both fluid and structure temperature fluctuations also agree well with the experimental results. Therefore, the numerical methods used in the present paper are

  11. CFD application to advanced design for high efficiency spacer grid

    International Nuclear Information System (INIS)

    Ikeda, Kazuo

    2014-01-01

    Highlights: • A new LDV was developed to investigate the local velocity in a rod bundle and inside a spacer grid. • The design information that utilizes for high efficiency spacer grid has been obtained. • CFD methodology that predicts flow field in a PWR fuel has been developed. • The high efficiency spacer grid was designed using the CFD methodology. - Abstract: Pressurized water reactor (PWR) fuels have been developed to meet the needs of the market. A spacer grid is a key component to improve thermal hydraulic performance of a PWR fuel assembly. Mixing structures (vanes) of a spacer grid promote coolant mixing and enhance heat removal from fuel rods. A larger mixing vane would improve mixing effect, which would increase the departure from nucleate boiling (DNB) benefit for fuel. However, the increased pressure loss at large mixing vanes would reduce the coolant flow at the mixed fuel core, which would reduce the DNB margin. The solution is to develop a spacer grid whose pressure loss is equal to or less than the current spacer grid and that has higher critical heat flux (CHF) performance. For this reason, a requirement of design tool for predicting the pressure loss and CHF performance of spacer grids has been increased. The author and co-workers have been worked for development of high efficiency spacer grid using Computational Fluid Dynamics (CFD) for nearly 20 years. A new laser Doppler velocimetry (LDV), which is miniaturized with fiber optics embedded in a fuel cladding, was developed to investigate the local velocity profile in a rod bundle and inside a spacer grid. The rod-embedded fiber LDV (rod LDV) can be inserted in an arbitrary grid cell instead of a fuel rod, and has the advantage of not disturbing the flow field since it is the same shape as a fuel rod. The probe volume of the rod LDV is small enough to measure spatial velocity profile in a rod gap and inside a spacer grid. According to benchmark experiments such as flow velocity

  12. CFD application to advanced design for high efficiency spacer grid

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Kazuo, E-mail: kazuo3_ikeda@ndc.mhi.co.jp

    2014-11-15

    Highlights: • A new LDV was developed to investigate the local velocity in a rod bundle and inside a spacer grid. • The design information that utilizes for high efficiency spacer grid has been obtained. • CFD methodology that predicts flow field in a PWR fuel has been developed. • The high efficiency spacer grid was designed using the CFD methodology. - Abstract: Pressurized water reactor (PWR) fuels have been developed to meet the needs of the market. A spacer grid is a key component to improve thermal hydraulic performance of a PWR fuel assembly. Mixing structures (vanes) of a spacer grid promote coolant mixing and enhance heat removal from fuel rods. A larger mixing vane would improve mixing effect, which would increase the departure from nucleate boiling (DNB) benefit for fuel. However, the increased pressure loss at large mixing vanes would reduce the coolant flow at the mixed fuel core, which would reduce the DNB margin. The solution is to develop a spacer grid whose pressure loss is equal to or less than the current spacer grid and that has higher critical heat flux (CHF) performance. For this reason, a requirement of design tool for predicting the pressure loss and CHF performance of spacer grids has been increased. The author and co-workers have been worked for development of high efficiency spacer grid using Computational Fluid Dynamics (CFD) for nearly 20 years. A new laser Doppler velocimetry (LDV), which is miniaturized with fiber optics embedded in a fuel cladding, was developed to investigate the local velocity profile in a rod bundle and inside a spacer grid. The rod-embedded fiber LDV (rod LDV) can be inserted in an arbitrary grid cell instead of a fuel rod, and has the advantage of not disturbing the flow field since it is the same shape as a fuel rod. The probe volume of the rod LDV is small enough to measure spatial velocity profile in a rod gap and inside a spacer grid. According to benchmark experiments such as flow velocity

  13. Using CFD as Rocket Injector Design Tool: Recent Progress at Marshall Space Flight Center

    Science.gov (United States)

    Tucker, Kevin; West, Jeff; Williams, Robert; Lin, Jeff; Rocker, Marvin; Canabal, Francisco; Robles, Bryan; Garcia, Robert; Chenoweth, James

    2003-01-01

    The choice of tools used for injector design is in a transitional phase between exclusive reliance on the empirically based correlations and extensive use of computational fluid dynamics (CFD). The Next Generation Launch Technology (NGLT) Program goals emphasizing lower costs and increased reliability have produced a need to enable CFD as an injector design tool in a shorter time frame. This is the primary objective of the Staged Combustor Injector Technology Task currently under way at Marshall Space Flight Center (MSFC). The documentation of this effort begins with a very brief status of current injector design tools. MSFC's vision for use of CFD as a tool for combustion devices design is stated and discussed with emphasis on the injector. The concept of the Simulation Readiness Level (SRL), comprised of solution fidelity, robustness and accuracy, is introduced and discussed. This quantitative measurement is used to establish the gap between the current state of demonstrated capability and that necessary for regular use in the design process. MSFC's view of the validation process is presented and issues associated with obtaining the necessary data are noted and discussed. Three current experimental efforts aimed at generating validation data are presented. The importance of uncertainty analysis to understand the data quality is also demonstrated. First, a brief status of current injector design tools is provided as context for the current effort. Next, the MSFC vision for using CFD as an injector design tool is stated. A generic CFD-based injector design methodology is also outlined and briefly discussed. Three areas where MSFC is using injector CFD analyses for program support will be discussed. These include the Integrated Powerhead Development (IPD) engine which uses hydrogen and oxygen propellants in a full flow staged combustion (FFSC) cycle and the TR-107 and the RS84 engine both of which use RP-1 and oxygen in an ORSC cycle. Finally, an attempt is made to

  14. Coupled in silico platform: Computational fluid dynamics (CFD) and physiologically-based pharmacokinetic (PBPK) modelling.

    Science.gov (United States)

    Vulović, Aleksandra; Šušteršič, Tijana; Cvijić, Sandra; Ibrić, Svetlana; Filipović, Nenad

    2018-02-15

    One of the critical components of the respiratory drug delivery is the manner in which the inhaled aerosol is deposited in respiratory tract compartments. Depending on formulation properties, device characteristics and breathing pattern, only a certain fraction of the dose will reach the target site in the lungs, while the rest of the drug will deposit in the inhalation device or in the mouth-throat region. The aim of this study was to link the Computational fluid dynamics (CFD) with physiologically-based pharmacokinetic (PBPK) modelling in order to predict aerolisolization of different dry powder formulations, and estimate concomitant in vivo deposition and absorption of amiloride hydrochloride. Drug physicochemical properties were experimentally determined and used as inputs for the CFD simulations of particle flow in the generated 3D geometric model of Aerolizer® dry powder inhaler (DPI). CFD simulations were used to simulate air flow through Aerolizer® inhaler and Discrete Phase Method (DPM) was used to simulate aerosol particles deposition within the fluid domain. The simulated values for the percent emitted dose were comparable to the values obtained using Andersen cascade impactor (ACI). However, CFD predictions indicated that aerosolized DPI have smaller particle size and narrower size distribution than assumed based on ACI measurements. Comparison with the literature in vivo data revealed that the constructed drug-specific PBPK model was able to capture amiloride absorption pattern following oral and inhalation administration. The PBPK simulation results, based on the CFD generated particle distribution data as input, illustrated the influence of formulation properties on the expected drug plasma concentration profiles. The model also predicted the influence of potential changes in physiological parameters on the extent of inhaled amiloride absorption. Overall, this study demonstrated the potential of the combined CFD-PBPK approach to model inhaled drug

  15. Toward a CFD-grade database addressing LWR containment phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Paladino, Domenico, E-mail: domenico.paladino@psi.ch [Laboratory for Thermal-Hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Andreani, Michele; Zboray, Robert; Dreier, Joerg [Laboratory for Thermal-Hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer The SETH-2 PANDA tests have supplied data with CFD-grade on plumes and jets at large-scale. Black-Right-Pointing-Pointer The PANDA tests have contributed to the understanding of phenomena with high safety relevance for LWRs. Black-Right-Pointing-Pointer The analytical activities related increased confidence in the use of various computational tools for safety analysis. - Abstract: The large-scale, multi-compartment PANDA facility (located at PSI in Switzerland) is one of the state-of-the-art facilities which is continuously upgraded to progressively match the requirements of CFD-grade experiments. Within the OECD/SETH projects, the PANDA facility has been used for the creation of an experimental database on basic containment phenomena e.g. gas mixing, transport, stratification, condensation. In the PANDA tests, these phenomena are driven by large scale plumes or jets. In the paper is presented a selection of the SETH PANDA experimental results. Examples of analytical activities performed at PSI using the GOTHIC, CFX-4 and CFX-5 codes will be used to illustrate how the spatial and temporal resolutions of the measurement grid in PANDA tests are adequate for CFD code (and advanced containment codes) assessment and validation purposes.

  16. AirShow 1.0 CFD Software Users' Guide

    Science.gov (United States)

    Mohler, Stanley R., Jr.

    2005-01-01

    AirShow is visualization post-processing software for Computational Fluid Dynamics (CFD). Upon reading binary PLOT3D grid and solution files into AirShow, the engineer can quickly see how hundreds of complex 3-D structured blocks are arranged and numbered. Additionally, chosen grid planes can be displayed and colored according to various aerodynamic flow quantities such as Mach number and pressure. The user may interactively rotate and translate the graphical objects using the mouse. The software source code was written in cross-platform Java, C++, and OpenGL, and runs on Unix, Linux, and Windows. The graphical user interface (GUI) was written using Java Swing. Java also provides multiple synchronized threads. The Java Native Interface (JNI) provides a bridge between the Java code and the C++ code where the PLOT3D files are read, the OpenGL graphics are rendered, and numerical calculations are performed. AirShow is easy to learn and simple to use. The source code is available for free from the NASA Technology Transfer and Partnership Office.

  17. Pilot-in-the-Loop CFD Method Development

    Science.gov (United States)

    2017-02-01

    linear behavior of the rotor/terrain interactions. However these fluctuations are not as strong as we saw in the hover IGE cases. Helicopter shows...West Palm Beach, FL, May 2016. Oruc, I., Horn, J.F., Shipman, J., and Shenoy, R., “Coupled Flight Dynamics and CFD Simulations of the

  18. Investigation on the Use of a Multiphase Eulerian CFD solver to simulate breaking waves

    DEFF Research Database (Denmark)

    Tomaselli, Pietro D.; Christensen, Erik Damgaard

    2015-01-01

    investigation on a CFD model capable of handling this problem. The model is based on a solver, available in the open-source CFD toolkit OpenFOAM, which combines the Eulerian multi-fluid approach for dispersed flows with a numerical interface sharpening method. The solver, enhanced with additional formulations...

  19. CFD Analysis of Scale Effects on Conventional and Tip-Modified Propellers

    DEFF Research Database (Denmark)

    Shin, Keun Woo; Andersen, Poul

    2017-01-01

    Full-scale propeller performance is traditionally predictedby scaling model-scale test results, but the traditionalscaling methods do not take into account hydrodynamicdistinctions of tip-modified propellers in full-scaleperformance. An open-water CFD analysis is made onscale effects of tip...... the transition model shows that laminar and transitionalflow modeling is crucial in model-scale computations.Grid-independent solutions at model and full scale areachieved by grid verification studies. The CFD analysis of scale effects shows that theefficiency gain of the tip-modified propeller is increasedat...

  20. CFD validation of a supercritical water flow for SCWR design heat and mass fluxes

    International Nuclear Information System (INIS)

    Roelofs, F.; Lycklama a Nijeholt, J.A.; Komen, E.M.J.; Lowenberg, M.; Starflinger, J.

    2007-01-01

    The applicability of Computational Fluid Dynamics (CFD) for water under supercritical conditions in supercritical water reactors (SCWR) has still to be verified. In the recent past, CFD validation analyses were performed by various institutes for supercritical water in vertical tubes based on the well known experimental data from Yamagata. However, validation using data from experiments with working conditions closer to the actual operational conditions of such reactors is needed. From a literature survey the experiments performed by Herkenrath are selected to perform validation analyses at higher heat fluxes and a higher mass flux. The accuracy of CFD using RANS (Reynolds Average Navier-Stokes) turbulence modelling for supercritical fluids under conditions close to the operational conditions of a supercritical water reactor is determined. It is concluded that the wall temperature can be predicted by RANS CFD, using the RNG k-ε turbulence model, with accuracy in the range of 5% for heat fluxes up to 1100 kW/m 2 and for a bulk enthalpy up to 2200 kJ/kg. For a bulk enthalpy exceeding 2200 kJ/kg, a significant lower accuracy of the CFD predictions (about 3%) is found for the simulations of the experiments of Yamagata in comparison with the simulations of the experiments of Herkenrath. For these experiments, the accuracy is about 18 per cent. This might be a result of the fact that the CFD analyses do not simulate the flattening of the temperature profile at about 2200 kJ/kg which is found in the experiments of Herkenrath. However, the obtained accuracies ranging from 3% to 18% are still deemed to be acceptable for many design purposes. (authors)

  1. Computational fluid dynamics (CFD) round robin benchmark for a pressurized water reactor (PWR) rod bundle

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Shin K., E-mail: paengki1@tamu.edu; Hassan, Yassin A.

    2016-05-15

    Highlights: • The capabilities of steady RANS models were directly assessed for full axial scale experiment. • The importance of mesh and conjugate heat transfer was reaffirmed. • The rod inner-surface temperature was directly compared. • The steady RANS calculations showed a limitation in the prediction of circumferential distribution of the rod surface temperature. - Abstract: This study examined the capabilities and limitations of steady Reynolds-Averaged Navier–Stokes (RANS) approach for pressurized water reactor (PWR) rod bundle problems, based on the round robin benchmark of computational fluid dynamics (CFD) codes against the NESTOR experiment for a 5 × 5 rod bundle with typical split-type mixing vane grids (MVGs). The round robin exercise against the high-fidelity, broad-range (covering multi-spans and entire lateral domain) NESTOR experimental data for both the flow field and the rod temperatures enabled us to obtain important insights into CFD prediction and validation for the split-type MVG PWR rod bundle problem. It was found that the steady RANS turbulence models with wall function could reasonably predict two key variables for a rod bundle problem – grid span pressure loss and the rod surface temperature – once mesh (type, resolution, and configuration) was suitable and conjugate heat transfer was properly considered. However, they over-predicted the magnitude of the circumferential variation of the rod surface temperature and could not capture its peak azimuthal locations for a central rod in the wake of the MVG. These discrepancies in the rod surface temperature were probably because the steady RANS approach could not capture unsteady, large-scale cross-flow fluctuations and qualitative cross-flow pattern change due to the laterally confined test section. Based on this benchmarking study, lessons and recommendations about experimental methods as well as CFD methods were also provided for the future research.

  2. A Two-Temperature Open-Source CFD Model for Hypersonic Reacting Flows, Part One: Zero-Dimensional Analysis

    OpenAIRE

    Vincent Casseau; Rodrigo C. Palharini; Thomas J. Scanlon; Richard E. Brown

    2016-01-01

    A two-temperature CFD (computational fluid dynamics) solver is a prerequisite to any spacecraft re-entry numerical study that aims at producing results with a satisfactory level of accuracy within realistic timescales. In this respect, a new two-temperature CFD solver, hy2Foam, has been developed within the framework of the open-source CFD platform OpenFOAM for the prediction of hypersonic reacting flows. This solver makes the distinct juncture between the trans-rotational and multiple vibrat...

  3. Validation of a CFD methodology for positive displacement LVAD analysis using PIV data.

    Science.gov (United States)

    Medvitz, Richard B; Reddy, Varun; Deutsch, Steve; Manning, Keefe B; Paterson, Eric G

    2009-11-01

    Computational fluid dynamics (CFD) is used to asses the hydrodynamic performance of a positive displacement left ventricular assist device. The computational model uses implicit large eddy simulation direct resolution of the chamber compression and modeled valve closure to reproduce the in vitro results. The computations are validated through comparisons with experimental particle image velocimetry (PIV) data. Qualitative comparisons of flow patterns, velocity fields, and wall-shear rates demonstrate a high level of agreement between the computations and experiments. Quantitatively, the PIV and CFD show similar probed velocity histories, closely matching jet velocities and comparable wall-strain rates. Overall, it has been shown that CFD can provide detailed flow field and wall-strain rate data, which is important in evaluating blood pump performance.

  4. Concentration transport calculations by an original C++ program with interediate fidelity physics through user-defined buildings with an emphasis on release scenarios in radiological facilities

    Science.gov (United States)

    Sayre, George Anthony

    The purpose of this dissertation was to develop the C ++ program Emergency Dose to calculate transport of radionuclides through indoor spaces using intermediate fidelity physics that provides improved spatial heterogeneity over well-mixed models such as MELCORRTM and much lower computation times than CFD codes such as FLUENTRTM . Modified potential flow theory, which is an original formulation of potential flow theory with additions of turbulent jet and natural convection approximations, calculates spatially heterogeneous velocity fields that well-mixed models cannot predict. Other original contributions of MPFT are: (1) generation of high fidelity boundary conditions relative to well-mixed-CFD coupling methods (conflation), (2) broadening of potential flow applications to arbitrary indoor spaces previously restricted to specific applications such as exhaust hood studies, and (3) great reduction of computation time relative to CFD codes without total loss of heterogeneity. Additionally, the Lagrangian transport module, which is discussed in Sections 1.3 and 2.4, showcases an ensemble-based formulation thought to be original to interior studies. Velocity and concentration transport benchmarks against analogous formulations in COMSOLRTM produced favorable results with discrepancies resulting from the tetrahedral meshing used in COMSOLRTM outperforming the Cartesian method used by Emergency Dose. A performance comparison of the concentration transport modules against MELCORRTM showed that Emergency Dose held advantages over the well-mixed model especially in scenarios with many interior partitions and varied source positions. A performance comparison of velocity module against FLUENTRTM showed that viscous drag provided the largest error between Emergency Dose and CFD velocity calculations, but that Emergency Dose's turbulent jets well approximated the corresponding CFD jets. Overall, Emergency Dose was found to provide a viable intermediate solution method for

  5. Radial basis function networks applied to DNBR calculation in digital core protection systems

    International Nuclear Information System (INIS)

    Lee, Gyu-Cheon; Heung Chang, Soon

    2003-01-01

    The nuclear power plant has to be operated with sufficient margin from the specified DNBR limit for assuring its safety. The digital core protection system calculates on-line real-time DNBR by using a complex subchannel analysis program, and triggers a reliable reactor shutdown if the calculated DNBR approaches the specified limit. However, it takes a relatively long calculation time even for a steady state condition, which may have an adverse effect on the operation flexibility. To overcome the drawback, a new method using a radial basis function network is presented in this paper. Nonparametric training approach is utilized, which shows dramatic reduction of the training time, no tedious heuristic process for optimizing parameters, and no local minima problem during the training. The test results show that the predicted DNBR is within about ±2% deviation from the target DNBR for the fixed axial flux shape case. For the variable axial flux case including severely skewed shapes that appeared during accidents, the deviation is within about ±10%. The suggested method could be the alternative that can calculate DNBR very quickly while guaranteeing the plant safety

  6. CFD simulation of a four-loop PWR at asymmetric operation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jian-Ping; Yan, Li-Ming; Li, Feng-Chen, E-mail: lifch@hit.edu.cn

    2016-04-15

    Highlights: • A CFD numerical simulation procedure was established for simulating RPV of VVER-1000. • The established CFD approach was validated by comparing with available data. • Thermal hydraulic characteristics under asymmetric operation condition were investigated. • Apparent influences of the shutdown loop on its neighboring loops were obtained. - Abstract: The pressurized water reactor (PWR) with multiple loops may have abnormal working conditions with coolant pumps out of running in some loops. In this paper, a computational fluid dynamics (CFD) numerical study of the four-loop VVER-1000 PWR pressure vessel model was presented. Numerical simulations of the thermohydrodynamic characteristics in the pressure vessel were carried out at different inlet conditions with four and three loops running, respectively. At normal stead-state condition (four-loop running), different parameters were obtained for the full fluid domain, including pressure losses across different parts, pressure, velocity and temperature distributions in the reactor pressure vessel (RPV) and mass flow distribution of the coolant at the inlet of reactor core. The obtained results for pressure losses matched with the experimental reference values of the VVER-1000 PWR at Tianwan nuclear power plant (NPP). For most fuel assemblies (FAs), the inlet flow rates presented a symmetrical distribution about the center under full-loop operation conditions, which accorded with the practical distribution. These results indicate that it is now possible to study the dynamic transition process between different asymmetric operation conditions in a multi-loop PWR using the established CFD method.

  7. CFD Analysis for Assessing the Effect of Wind on the Thermal Control of the Mars Science Laboratory Curiosity Rover

    Science.gov (United States)

    Bhandari, Pradeep; Anderson, Kevin

    2013-01-01

    The challenging range of landing sites for which the Mars Science Laboratory Rover was designed, requires a rover thermal management system that is capable of keeping temperatures controlled across a wide variety of environmental conditions. On the Martian surface where temperatures can be as cold as -123 C and as warm as 38 C, the rover relies upon a Mechanically Pumped Fluid Loop (MPFL) Rover Heat Rejection System (RHRS) and external radiators to maintain the temperature of sensitive electronics and science instruments within a -40 C to 50 C range. The RHRS harnesses some of the waste heat generated from the rover power source, known as the Multi Mission Radioisotope Thermoelectric Generator (MMRTG), for use as survival heat for the rover during cold conditions. The MMRTG produces 110 W of electrical power while generating waste heat equivalent to approximately 2000 W. Heat exchanger plates (hot plates) positioned close to the MMRTG pick up this survival heat from it by radiative heat transfer. Winds on Mars can be as fast as 15 m/s for extended periods. They can lead to significant heat loss from the MMRTG and the hot plates due to convective heat pick up from these surfaces. Estimation of this convective heat loss cannot be accurately and adequately achieved by simple textbook based calculations because of the very complicated flow fields around these surfaces, which are a function of wind direction and speed. Accurate calculations necessitated the employment of sophisticated Computational Fluid Dynamics (CFD) computer codes. This paper describes the methodology and results of these CFD calculations. Additionally, these results are compared to simple textbook based calculations that served as benchmarks and sanity checks for them. And finally, the overall RHRS system performance predictions will be shared to show how these results affected the overall rover thermal performance.

  8. CFD study of ejector flow behavior in a blast furnace gas galvanizing plant

    Science.gov (United States)

    Besagni, Giorgio; Mereu, Riccardo; Inzoli, Fabio

    2015-02-01

    In recent years, there has been a growing interest toward Blast Furnace Gas (BFG) as a low-grade energy source for industrial furnaces. This paper considers the revamping of a galvanic plant furnace converted to BFG from natural gas. In the design of the new system, the ejector on the exhaust line is a critical component. This paper studies the flow behavior of the ejector using a Computational Fluid Dynamics (CFD) analysis. The CFD model is based on a 3D representation of the ejector, using air and exhaust gases as working fluids. This paper is divided in three parts. In the first part, the galvanic plant used as case study is presented and discussed, in the second part the CFD approach is outlined, and in the third part the CFD approach is validated using experimental data and the numerical results are presented and discussed. Different Reynolds-Averaged Navier-Stokes (RANS) turbulence models ( k-ω SST and k-ɛ Realizable) are evaluated in terms of convergence capability and accuracy in predicting the pressure drop along the ejector. Suggestions for future optimization of the system are also provided.

  9. CFD for evaluation and treatment planning of aneurysms: review of proposed clinical uses and their challenges.

    Science.gov (United States)

    Chung, Bongjae; Cebral, Juan Raul

    2015-01-01

    Computational fluid dynamics (CFD) has been used for several years to identify mechanical risk factors associated with aneurysmal evolution and rupture as well as to understand flow characteristics before and after surgical treatments in order to help the clinical decision making process. We used the keywords, "CFD" and "aneurysms" to search recent publications since about 2000, and categorized them into (i) studies of rupture risk factors and (ii) investigations of pre- and post-evaluations of surgical treatment with devices like coils and flow diverters (FD). This search enables us to examine the current status of CFD as a clinical tool and to determine if CFD can potentially become an important part of the routine clinical practice for the evaluation and treatment of aneurysms in near future. According to previous reports, it has been argued that CFD has become a quite robust non-invasive tool for the evaluation of surgical devices, especially in the early stages of device design and it has also been applied successfully to the study of rupture risk assessment. However, we find that due to the large number of pre-processing inputs further efforts of validation and reproducibility of CFD with larger clinical datasets are still essential to identify standardized mechanical risk factors. As a result, we identify the following needs to have a robust CFD tool for clinical use: (i) more reliability tests through validation studies, (ii) analyses of larger generalized clinical datasets to find converging universal risk parameters, (iii) fluid structure interaction (FSI) analyses to better understand the detailed vascular remodeling processes associated with aneurysm growth, evolution and rupture, and (iv) better coordinated and organized communications and collaborations between engineers and clinicians.

  10. Aerodynamic optimization of wind turbine rotor using CFD/AD method

    Science.gov (United States)

    Cao, Jiufa; Zhu, Weijun; Wang, Tongguang; Ke, Shitang

    2018-05-01

    The current work describes a novel technique for wind turbine rotor optimization. The aerodynamic design and optimization of wind turbine rotor can be achieved with different methods, such as the semi-empirical engineering methods and more accurate computational fluid dynamic (CFD) method. The CFD method often provides more detailed aerodynamics features during the design process. However, high computational cost limits the application, especially for rotor optimization purpose. In this paper, a CFD-based actuator disc (AD) model is used to represent turbulent flow over a wind turbine rotor. The rotor is modeled as a permeable disc of equivalent area where the forces from the blades are distributed on the circular disc. The AD model is coupled with a Reynolds Averaged Navier-Stokes (RANS) solver such that the thrust and power are simulated. The design variables are the shape parameters comprising the chord, the twist and the relative thickness of the wind turbine rotor blade. The comparative aerodynamic performance is analyzed between the original and optimized reference wind turbine rotor. The results showed that the optimization framework can be effectively and accurately utilized in enhancing the aerodynamic performance of the wind turbine rotor.

  11. A Predictive Framework to Elucidate Venous Stenosis: CFD & Shape Optimization.

    Science.gov (United States)

    Javid Mahmoudzadeh Akherat, S M; Cassel, Kevin; Boghosian, Michael; Hammes, Mary; Coe, Fredric

    2017-07-01

    The surgical creation of vascular accesses for renal failure patients provides an abnormally high flow rate conduit in the patient's upper arm vasculature that facilitates the hemodialysis treatment. These vascular accesses, however, are very often associated with complications that lead to access failure and thrombotic incidents, mainly due to excessive neointimal hyperplasia (NH) and subsequently stenosis. Development of a framework to monitor and predict the evolution of the venous system post access creation can greatly contribute to maintaining access patency. Computational fluid dynamics (CFD) has been exploited to inspect the non-homeostatic wall shear stress (WSS) distribution that is speculated to trigger NH in the patient cohort under investigation. Thereafter, CFD in liaison with a gradient-free shape optimization method has been employed to analyze the deformation modes of the venous system enduring non-physiological hemodynamics. It is observed that the optimally evolved shapes and their corresponding hemodynamics strive to restore the homeostatic state of the venous system to a normal, pre-surgery condition. It is concluded that a CFD-shape optimization coupling that seeks to regulate the WSS back to a well-defined physiological WSS target range can accurately predict the mode of patient-specific access failure.

  12. CFD voor een gezonde en comfortabele stedelijke omgeving

    NARCIS (Netherlands)

    Blocken, B.J.E.

    2010-01-01

    Stedebouwfysica omvat de studie van fysische processen om te zorgen voor een gezonde, comfortabele en duurzame stedelijke omgeving. Dit artikel bespreekt kort de belangrijke rol die CFD-simulaties hierin kunnen spelen, op voorwaarde dat hun nauwkeurigheid en betrouwbaarheid gegarandeerd zijn. Het

  13. Considering value of information when using CFD in design

    Energy Technology Data Exchange (ETDEWEB)

    Misra, John Satprim [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    This thesis presents an approach to find lower resolution CFD models that can accurately lead a designer to a correct decision at a lower computational cost. High-fidelity CFD models often contain too much information and come at a higher computational cost, limiting the designs a designer can test and how much optimization can be performed on the design. Lower model resolution is commonly used to reduce computational time. However there are no clear guidelines on how much model accuracy is required. Instead experience and intuition are used to select an appropriate lower resolution model. This thesis presents an alternative to this ad hoc method by considering the added value of the addition information provided by increasing accurate and more computationally expensive models.

  14. CFD [computational fluid dynamics] And Safety Factors. Computer modeling of complex processes needs old-fashioned experiments to stay in touch with reality.

    Energy Technology Data Exchange (ETDEWEB)

    Leishear, Robert A.; Lee, Si Y.; Poirier, Michael R.; Steeper, Timothy J.; Ervin, Robert C.; Giddings, Billy J.; Stefanko, David B.; Harp, Keith D.; Fowley, Mark D.; Van Pelt, William B.

    2012-10-07

    Computational fluid dynamics (CFD) is recognized as a powerful engineering tool. That is, CFD has advanced over the years to the point where it can now give us deep insight into the analysis of very complex processes. There is a danger, though, that an engineer can place too much confidence in a simulation. If a user is not careful, it is easy to believe that if you plug in the numbers, the answer comes out, and you are done. This assumption can lead to significant errors. As we discovered in the course of a study on behalf of the Department of Energy's Savannah River Site in South Carolina, CFD models fail to capture some of the large variations inherent in complex processes. These variations, or scatter, in experimental data emerge from physical tests and are inadequately captured or expressed by calculated mean values for a process. This anomaly between experiment and theory can lead to serious errors in engineering analysis and design unless a correction factor, or safety factor, is experimentally validated. For this study, blending times for the mixing of salt solutions in large storage tanks were the process of concern under investigation. This study focused on the blending processes needed to mix salt solutions to ensure homogeneity within waste tanks, where homogeneity is required to control radioactivity levels during subsequent processing. Two of the requirements for this task were to determine the minimum number of submerged, centrifugal pumps required to blend the salt mixtures in a full-scale tank in half a day or less, and to recommend reasonable blending times to achieve nearly homogeneous salt mixtures. A full-scale, low-flow pump with a total discharge flow rate of 500 to 800 gpm was recommended with two opposing 2.27-inch diameter nozzles. To make this recommendation, both experimental and CFD modeling were performed. Lab researchers found that, although CFD provided good estimates of an average blending time, experimental blending times varied

  15. Estimation of left ventricular blood flow parameters: clinical application of patient-specific CFD simulations from 4D echocardiography

    Science.gov (United States)

    Larsson, David; Spühler, Jeannette H.; Günyeli, Elif; Weinkauf, Tino; Hoffman, Johan; Colarieti-Tosti, Massimiliano; Winter, Reidar; Larsson, Matilda

    2017-03-01

    Echocardiography is the most commonly used image modality in cardiology, assessing several aspects of cardiac viability. The importance of cardiac hemodynamics and 4D blood flow motion has recently been highlighted, however such assessment is still difficult using routine echo-imaging. Instead, combining imaging with computational fluid dynamics (CFD)-simulations has proven valuable, but only a few models have been applied clinically. In the following, patient-specific CFD-simulations from transthoracic dobutamin stress echocardiography have been used to analyze the left ventricular 4D blood flow in three subjects: two with normal and one with reduced left ventricular function. At each stress level, 4D-images were acquired using a GE Vivid E9 (4VD, 1.7MHz/3.3MHz) and velocity fields simulated using a presented pathway involving endocardial segmentation, valve position identification, and solution of the incompressible Navier-Stokes equation. Flow components defined as direct flow, delayed ejection flow, retained inflow, and residual volume were calculated by particle tracing using 4th-order Runge-Kutta integration. Additionally, systolic and diastolic average velocity fields were generated. Results indicated no major changes in average velocity fields for any of the subjects. For the two subjects with normal left ventricular function, increased direct flow, decreased delayed ejection flow, constant retained inflow, and a considerable drop in residual volume was seen at increasing stress. Contrary, for the subject with reduced left ventricular function, the delayed ejection flow increased whilst the retained inflow decreased at increasing stress levels. This feasibility study represents one of the first clinical applications of an echo-based patient-specific CFD-model at elevated stress levels, and highlights the potential of using echo-based models to capture highly transient flow events, as well as the ability of using simulation tools to study clinically complex

  16. Operational Augmentation of Forced Circulation Type Solar Dryer System Using CFD Analysis

    OpenAIRE

    Atul Patel; Gaurav Patel

    2014-01-01

    Solar drying is basically heat and mass transfer process in which the liquid water from the surface and the vapour removed by draft. The efficiency of a solar drying system is affected by the properties of drying materials.e.g. size, shape and geometry as well as ambient conditions. In this research article, the authors have done the CFD analysis of a Forced Circulation type Solar Dryer used conventionally for dehydrating vegetables and fruits. Using CFD analysis, the limiting...

  17. Numerical investigations of cooling holes system role in the protection of the walls of a gas turbine combustion chamber

    Energy Technology Data Exchange (ETDEWEB)

    Ben Sik Ali, Ahlem; Kriaa, Wassim; Mhiri, Hatem [Ecole Nationale D' Ingenieurs de Monastir, Unite de Thermique et Thermodynamique des Procedes industriels, Monastir (Tunisia); Bournot, Philippe [IUSTI, UMR CNRS 6595, Marseille (France)

    2012-05-15

    Numerical simulations in a gas turbine Swirl stabilized combustor were conducted to investigate the effectiveness of a cooling system in the protection of combustor walls. The studied combustion chamber has a high degree of geometrical complexity related to the injection system as well as the cooling system based on a big distribution of small holes (about 3,390 holes) bored on the flame tube walls. Two cases were considered respectively the flame tube without and with its cooling system. The calculations were carried out using the industrial CFD code FLUENT 6.2. The various simulations made it possible to highlight the role of cooling holes in the protection of the flame tube walls against the high temperatures of the combustion products. In fact, the comparison between the results of the two studied cases demonstrated that the walls temperature can be reduced by about 800 C by the mean of cooling holes technique. (orig.)

  18. Unsteady aerodynamics simulation of a full-scale horizontal axis wind turbine using CFD methodology

    International Nuclear Information System (INIS)

    Cai, Xin; Gu, Rongrong; Pan, Pan; Zhu, Jie

    2016-01-01

    Highlights: • A full-scale HAWT is simulated under operational conditions of wind shear and yaw. • The CFD method and sliding mesh are adopted to complete the calculation. • Thrust and torque of blades reach the peak and valley at the same time in wind shear. • The wind turbine produces yaw moment during the whole revolution in yaw case. • The torques and thrusts of the three blades present cyclical changes. - Abstract: The aerodynamic performance of wind turbines is significantly influenced by the unsteady flow around the rotor blades. The research on unsteady aerodynamics for Horizontal Axis Wind Turbines (HAWTs) is still poorly understood because of the complex flow physics. In this study, the unsteady aerodynamic configuration of a full-scale HAWT is simulated with consideration of wind shear, tower shadow and yaw motion. The calculated wind turbine which contains tapered tower, rotor overhang and tilted rotor shaft is constructed by making reference of successfully commercial operated wind turbine designed by NEG Micon and Vestas. A validated CFD method is utilized to analyze unsteady aerodynamic characteristics which affect the performance on such a full-scale HAWT. The approach of sliding mesh is used to carefully deal with the interface between static and moving parts in the flow field. The annual average wind velocity and wind profile in the atmospheric border are applied as boundary conditions. Considering the effects of wind shear and tower shadow, the simulation results show that the each blade reaches its maximum and minimum aerodynamic loads almost at the same time during the rotation circle. The blade–tower interaction imposes great impact on the power output performance. The wind turbine produces yaw moment during the whole revolution and the maximum aerodynamic loads appear at the upwind azimuth in the yaw computation case.

  19. MPI to Coarray Fortran: Experiences with a CFD Solver for Unstructured Meshes

    Directory of Open Access Journals (Sweden)

    Anuj Sharma

    2017-01-01

    Full Text Available High-resolution numerical methods and unstructured meshes are required in many applications of Computational Fluid Dynamics (CFD. These methods are quite computationally expensive and hence benefit from being parallelized. Message Passing Interface (MPI has been utilized traditionally as a parallelization strategy. However, the inherent complexity of MPI contributes further to the existing complexity of the CFD scientific codes. The Partitioned Global Address Space (PGAS parallelization paradigm was introduced in an attempt to improve the clarity of the parallel implementation. We present our experiences of converting an unstructured high-resolution compressible Navier-Stokes CFD solver from MPI to PGAS Coarray Fortran. We present the challenges, methodology, and performance measurements of our approach using Coarray Fortran. With the Cray compiler, we observe Coarray Fortran as a viable alternative to MPI. We are hopeful that Intel and open-source implementations could be utilized in the future.

  20. Aerodynamic study of time-trial helmets in cycling racing using CFD analysis.

    Science.gov (United States)

    Beaumont, F; Taiar, R; Polidori, G; Trenchard, H; Grappe, F

    2018-01-23

    The aerodynamic drag of three different time-trial cycling helmets was analyzed numerically for two different cyclist head positions. Computational Fluid Dynamics (CFD) methods were used to investigate the detailed airflow patterns around the cyclist for a constant velocity of 15 m/s without wind. The CFD simulations have focused on the aerodynamic drag effects in terms of wall shear stress maps and pressure coefficient distributions on the cyclist/helmet system. For a given head position, the helmet shape, by itself, obtained a weak effect on a cyclist's aerodynamic performance (CFD results have also shown that both helmet shape and head position significantly influence drag forces, pressure and wall shear stress distributions on the whole cyclist's body due to the change in the near-wake behavior and in location of corresponding separation and attachment areas around the cyclist. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Benchmark and parametric study of a passive flow controller (fluidic device) for the development of optimal designs using a CFD code

    International Nuclear Information System (INIS)

    Lim, Sang-Gyu; Lee, Seok-Ho; Kim, Han-Gon

    2010-01-01

    A passive flow controller or a fluidic device (FD) is used for a safety injection system (SIS) for efficient use of nuclear reactor emergency cooling water since it can control the injection flow rate in a passive and optimal way. The performance of the FD is represented by pressure loss coefficient (K-factor) which is further affected by the configuration of the components such as a control port direction and a nozzle angle. The flow control mechanism that is varied according to the water level inside a vortex chamber determines the duration of the safety injection. This paper deals with a computational fluid dynamics (CFD) analysis for simulating the flow characteristics of the FD using the ANSYS CFX 11.0. The CFD analysis is benchmarked against existing experimental data to obtain applicability to the prediction of the FD performance in terms of K-factor. The CFD calculation is implemented with Shear Stress Transport (SST) model for a swirling flow and a strong streamline curvature in the vortex chamber of the FD, considering a numerical efficiency. Based on the benchmark results, parametric analyses are performed for an optimal design of the FD by varying the control port direction and the nozzle angle. Consequently, the FD performance is enhanced according to the angle of the control port nozzle.

  2. Application of Scaling-Law and CFD Modeling to Hydrodynamics of Circulating Biomass Fluidized Bed Gasifier

    Directory of Open Access Journals (Sweden)

    Mazda Biglari

    2016-06-01

    Full Text Available Two modeling approaches, the scaling-law and CFD (Computational Fluid Dynamics approaches, are presented in this paper. To save on experimental cost of the pilot plant, the scaling-law approach as a low-computational-cost method was adopted and a small scale column operating under ambient temperature and pressure was built. A series of laboratory tests and computer simulations were carried out to evaluate the hydrodynamic characteristics of a pilot fluidized-bed biomass gasifier. In the small scale column solids were fluidized. The pressure and other hydrodynamic properties were monitored for the validation of the scaling-law application. In addition to the scaling-law modeling method, the CFD approach was presented to simulate the gas-particle system in the small column. 2D CFD models were developed to simulate the hydrodynamic regime. The simulation results were validated with the experimental data from the small column. It was proved that the CFD model was able to accurately predict the hydrodynamics of the small column. The outcomes of this research present both the scaling law with the lower computational cost and the CFD modeling as a more robust method to suit various needs for the design of fluidized-bed gasifiers.

  3. Direct CFD Predictions of Low Frequency Sounds Generated by a Helicopter Main Rotor

    Science.gov (United States)

    Sim, Ben W.; Potsdam, Mark A.; Conner, Dave A.; Conner, Dave A.; Watts, Michael E.

    2010-01-01

    The use of CFD to directly predict helicopter main rotor noise is shown to be quite promising as an alternative mean for low frequency source noise evaluation. Results using existing state-of-the-art grid structures and finite-difference schemes demonstrated that small perturbation pressures, associated with acoustics radiation, can be extracted with some degree of fidelity. Accuracy of the predictions are demonstrated via comparing to predictions from conventional acoustic analogy-based models, and with measurements obtained from wind tunnel and flight tests for the MD-902 helicopter at several operating conditions. Findings show that the direct CFD approach is quite successfully in yielding low frequency results due to thickness and steady loading noise mechanisms. Mid-to-high frequency contents, due to blade-vortex interactions, are not predicted due to CFD modeling and grid constraints.

  4. Effect of accessory ostia on maxillary sinus ventilation: a computational fluid dynamics (CFD) study.

    Science.gov (United States)

    Zhu, Jian Hua; Lee, Heow Pueh; Lim, Kian Meng; Gordon, Bruce R; Wang, De Yun

    2012-08-15

    We evaluated, by CFD simulation, effects of accessory ostium (AO) on maxillary sinus ventilation. A three-dimensional nasal model was constructed from an adult CT scan with two left maxillary AOs (sinus I) and one right AO (sinus II), then compared to an identical control model with all AOs sealed (sinuses III and IV). Transient simulations of quiet inspiration and expiration at 15 L/min, and nasal blow at 48 L/min, were calculated for both models using low-Reynolds-number turbulent analysis. At low flows, ventilation rates in sinuses with AOs (I ≈ 0.46 L/min, II ≈ 0.54 L/min), were both more than a magnitude higher than sinuses without AOs (II I ≈ 0.019 L/min, IV ≈ 0.020 L/min). Absence of AO almost completely prevented sinus ventilation. Increased ventilation of sinuses with AOs is complex. Under high flow conditions mimicking nose blowing, in sinuses II, III, and IV, the sinus flow rate increased. In contrast, the airflow direction through sinus I reversed between inspiration and expiration, while it remained almost constant throughout the respiration cycle in sinus II. CFD simulation demonstrated that AOs markedly increase maxillary sinus airflow rates and alter sinus air circulation patterns. Whether these airflow changes impact maxillary sinus physiology or pathophysiology is unknown. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. RANS based CFD methodology for a real scale 217-pin wire-wrapped fuel assembly of KAERI PGSFR

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jae-Ho, E-mail: jhjeong@kaeri.re.kr [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseoung-gu, Daejeon (Korea, Republic of); Song, Min-Seop [Department of Nuclear Engineering, Seoul National University, 559 Gwanak-ro, Gwanak-gu, Seoul (Korea, Republic of); Lee, Kwi-Lim [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseoung-gu, Daejeon (Korea, Republic of)

    2017-03-15

    Highlights: • This paper presents a suitable way for a practical RANS based CFD methodology which is applicable to real scale 217-pin wire-wrapped fuel assembly of KAERI PGSFR. • A key point of differentiation of the RANS based CFD methodology in this study is adapting an innovative grid generation method using a fortran based in-house code with a GGI function in a general-purpose commercial CFD code, CFX. • The RANS based CFD methodology is implemented with high resolution scheme and SST turbulence model in the 7-pin 37-pin, and 127-pin wire-wrapped fuel assembly of PNC and JNC. Furthermore, the RANS based CFD methodology can be successfully extended to the real scale 217-pin wire-wrapped fuel bundles of KAERI PGSFR. • Three-dimensional thermal-hydraulic characteristics have been also investigated briefly. - Abstract: This paper presents a suitable way for a practical RANS (Reynolds Averaged Navier-Stokes simulation) based CFD (Computational Fluid Dynamics) methodology which is applicable to real scale 217-pin wire-wrapped fuel assembly of KAERI (Korea Atomic Energy Research Institute) PGSFR (Prototype Gen-IV Sodium-cooled Fast Reactor). The main purpose of the current study is to support license issue for the KAERI PGSFR core safety and to elucidate thermal-hydraulic characteristics in a 217-pin wire-wrapped fuel assembly of KAERI PGSFR. A key point of differentiation of the RANS based CFD methodology in this study is adapting an innovative grid generation method using a fortran based in-house code with a GGI (General Grid Interface) function in a general-purpose commercial CFD code, CFX. The innovative grid generation method with GGI function can achieve to simulate a real wire shape with minimizing cell skewness. The RANS based CFD methodology is implemented with high resolution scheme in convection term and SST (Shear Stress Transport) turbulence model in the 7-pin 37-pin, and 127-pin wire-wrapped fuel assembly of PNC (Power reactor and Nuclear fuel

  6. Significance and principles of the calculation of the effective dose equivalent for radiological protection of personnel and patients

    International Nuclear Information System (INIS)

    Drexler, G.; Williams, G.

    1985-01-01

    The application of the effective dose equivalent, Hsub(E), concept for radiological protection assessments of occupationally exposed persons is justifiable by the practicability thus achieved with regard to the limiting principles. Nevertheless, it would be proper logic to further use as the basic limiting quantity the real physical dose equivalent of homogeneous whole-body exposure, and for inhomogeneous whole-body irradiation the Hsub(E) value, calculated by means of the concept of the effective dose equivalent. For then the required concepts, models and calculations would not be connected with a basic radiation protection quantity. Application of the effective dose equivalent for radiation protection assessments for patients is misleading and is not practical with regard to assessing an individual or collective radiation risk of patients. The quantity of expected harm would be better suited to this purpose. There is no need to express the radiation risk by a dose quantity, which means careless handling of good information. (orig./WU) [de

  7. Analysis of a natural exhaust fan in a building of houses through thermal simulations and CFD; Analisis de un sistema de ventilacion natural en un edificio de viviendas a traves de simulaciones termicas y CFD

    Energy Technology Data Exchange (ETDEWEB)

    Bueno, B.; Cejudo, J.; Carrillo, A.

    2008-07-01

    Computational fluid dynamics (CFD) application to building energy simulation (STE) allows better modelling of indoor air performance and therefore it can be used to optimize the design of natural ventilation systems. In this paper, a natural ventilation system based on thermal chimney applied to a residential building is analyzed. Energy Plus simulations are applied to an apartment and results are coupled to CFD simulations to determine ventilation rates and study convection in the space. CFD simulations are also applied to evaluate indoor air distribution and study how ventilation rate is affected by the pressure drop at ventilation grilles. (Author)

  8. Blood flow quantification using 1D CFD parameter identification

    Science.gov (United States)

    Brosig, Richard; Kowarschik, Markus; Maday, Peter; Katouzian, Amin; Demirci, Stefanie; Navab, Nassir

    2014-03-01

    Patient-specific measurements of cerebral blood flow provide valuable diagnostic information concerning cerebrovascular diseases rather than visually driven qualitative evaluation. In this paper, we present a quantitative method to estimate blood flow parameters with high temporal resolution from digital subtraction angiography (DSA) image sequences. Using a 3D DSA dataset and a 2D+t DSA sequence, the proposed algorithm employs a 1D Computational Fluid Dynamics (CFD) model for estimation of time-dependent flow values along a cerebral vessel, combined with an additional Advection Diffusion Equation (ADE) for contrast agent propagation. The CFD system, followed by the ADE, is solved with a finite volume approximation, which ensures the conservation of mass. Instead of defining a new imaging protocol to obtain relevant data, our cost function optimizes the bolus arrival time (BAT) of the contrast agent in 2D+t DSA sequences. The visual determination of BAT is common clinical practice and can be easily derived from and be compared to values, generated by a 1D-CFD simulation. Using this strategy, we ensure that our proposed method fits best to clinical practice and does not require any changes to the medical work flow. Synthetic experiments show that the recovered flow estimates match the ground truth values with less than 12% error in the mean flow rates.

  9. CFD evaluation of turbulence model on heat transfer in 5 × 5 rod bundles

    International Nuclear Information System (INIS)

    Chao Yanmeng; Yang Lixin; Zhang Yuxiang; Pang Zhengzheng

    2014-01-01

    Different turbulence models may lead to different results when analyzing fuel assemblies using computational fluid dynamics (CFD) method. In this paper, a 5 × 5 rod bundle model was built to analyze the relationship between flow and heat transfer. The pressure drop and Nu were calculated using ANSYS CFX. Three factors evaluating swirling flow and cross-flow were used to analyze the inner relationship between flow field and heat transfer. The performances of various turbulence models, including eddy viscosity model and Reynold stress model, were evaluated. The comparison between numerical and similar experimental results indicates that Reynold stress model is more appropriate for modeling flow features and heat transfer in spacer grids discussed in this paper. (authors)