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Sample records for aerodynamics performance cooling

  1. Advanced multistage turbine blade aerodynamics, performance, cooling, and heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Fleeter, S.; Lawless, P.B. [Purdue Univ., West Lafayette, IN (United States)

    1995-10-01

    The gas turbine has the potential for power production at the highest possible efficiency. The challenge is to ensure that gas turbines operate at the optimum efficiency so as to use the least fuel and produce minimum emissions. A key component to meeting this challenge is the turbine. Turbine performance, both aerodynamics and heat transfer, is one of the barrier advanced gas turbine development technologies. This is a result of the complex, highly three-dimensional and unsteady flow phenomena in the turbine. Improved turbine aerodynamic performance has been achieved with three-dimensional highly-loaded airfoil designs, accomplished utilizing Euler or Navier-Stokes Computational Fluid Dynamics (CFD) codes. These design codes consider steady flow through isolated blade rows. Thus they do not account for unsteady flow effects. However, unsteady flow effects have a significant impact on performance. Also, CFD codes predict the complete flow field. The experimental verification of these codes has traditionally been accomplished with point data - not corresponding plane field measurements. Thus, although advanced CFD predictions of the highly complex and three-dimensional turbine flow fields are available, corresponding data are not. To improve the design capability for high temperature turbines, a detailed understanding of the highly unsteady and three-dimensional flow through multi-stage turbines is necessary. Thus, unique data are required which quantify the unsteady three-dimensional flow through multi-stage turbine blade rows, including the effect of the film coolant flow. This requires experiments in appropriate research facilities in which complete flow field data, not only point measurements, are obtained and analyzed. Also, as design CFD codes do not account for unsteady flow effects, the next logical challenge and the current thrust in CFD code development is multiple-stage analyses that account for the interactions between neighboring blade rows.

  2. An Assessment of NASA Glenn's Aeroacoustic Experimental and Predictive Capabilities for Installed Cooling Fans. Part 1; Aerodynamic Performance

    Science.gov (United States)

    VanZante, Dale E.; Koch, L. Danielle; Wernet, Mark P.; Podboy, Gary G.

    2006-01-01

    Driven by the need for low production costs, electronics cooling fans have evolved differently than the bladed components of gas turbine engines which incorporate multiple technologies to enhance performance and durability while reducing noise emissions. Drawing upon NASA Glenn's experience in the measurement and prediction of gas turbine engine aeroacoustic performance, tests have been conducted to determine if these tools and techniques can be extended for application to the aerodynamics and acoustics of electronics cooling fans. An automated fan plenum installed in NASA Glenn's Acoustical Testing Laboratory was used to map the overall aerodynamic and acoustic performance of a spaceflight qualified 80 mm diameter axial cooling fan. In order to more accurately identify noise sources, diagnose performance limiting aerodynamic deficiencies, and validate noise prediction codes, additional aerodynamic measurements were recorded for two operating points: free delivery and a mild stall condition. Non-uniformities in the fan s inlet and exhaust regions captured by Particle Image Velocimetry measurements, and rotor blade wakes characterized by hot wire anemometry measurements provide some assessment of the fan aerodynamic performance. The data can be used to identify fan installation/design changes which could enlarge the stable operating region for the fan and improve its aerodynamic performance and reduce noise emissions.

  3. Experimental investigation of gas turbine airfoil aerodynamic performance without and with film cooling in an annular sector cascade

    Energy Technology Data Exchange (ETDEWEB)

    Wiers, S.H.

    2002-02-01

    subject, as well as state of the art in secondary flow, single cooling jet behavior and film cooling. An overview of existing linear, annular and rotating annular test facilities is also given. The second part deals with the design and instrumentation as well as the measuring technique used for the performed investigations. Surface flow visualization has been performed to get a first idea about the secondary flow. Aerodynamic performance measurements have been conducted by means of five-hole pneumatic pressure probe traverses at 98%, 106% and 140% of c{sub ax} downstream of the cascade to gain information about the secondary flow and primary loss distribution. The variation of the Reynolds number and turbulence level show an overall loss increase for higher turbulence levels and Reynolds numbers due to higher mixing losses. Experimental investigations in terms of surface flow visualization and 5 hole pressure probe traverse of the influence of film cooling on the secondary flow effects and the losses of the cascade have been performed on a modem three dimensional nozzle guide vane with shower head cooling at the leading edge, four film cooling rows at the suction side, two film cooling rows at the pressure side and trailing edge ejection. The results of the flow visualization and pressure probe traverse show that the secondary flow region is only slightly effected by the ejection of low momentum cooling air. The cooling jets are deflected towards the hub, due to the low energy contents. With increasing mass flux ratio, respectively momentum flux ratio, the expanded secondary flow area at the trailing edge decreases. A rapid increase of the mixing loss at the midsection for ejection of high mass flow ratios in a highly accelerated flow at the suction side is observed. The coolant is seen, in every case, to increase the loss compared with the uncooled case. This is in accordance with the findings of most authors with regard to airfoil surface cooling, but the decrease in

  4. SIMULATION OF COOLING TOWER AND INFLUENCE OF AERODYNAMIC ELEMENTS ON ITS WORK UNDER CONDITIONS OF WIND

    Directory of Open Access Journals (Sweden)

    K. V. Dobrego

    2014-01-01

    Full Text Available Modern Cooling Towers (CT may utilize different aerodynamic elements (deflectors, windbreak walls etc. aimed to improvement of its heat performance especially at the windy conditions. In this paper the effect of flow rotation in overshower zone of CT and windbreak walls on a capacity of tower evaporating unit in the windy condition is studied numerically. Geometry of the model corresponds to real Woo-Jin Power station, China. Analogy of heat and mass transfer was used that allowed to consider aerodynamic of one-dimension flow and carried out detailed 3D calculations applying modern PC. Heat transfer coefficient of irrigator and its hydrodynamic resistance were established according to experimental data on total air rate in cooling tower. Numerical model is tested and verified with experimental data.Nonlinear dependence of CT thermal performance on wind velocity is demonstrated with the minimum (critical wind velocity at ucr ~ 8 m/s for simulated system. Application of windbreak walls does not change the value of the critical wind velocity, but may improves performance of cooling unit at moderate and strong wind conditions. Simultaneous usage of windbreak walls and overshower deflectors may increase efficiency up to 20–30 % for the deflectors angle a = 60o. Simulation let one analyze aerodynamic patterns, induced inside cooling tower and homogeneity of velocities’ field in irrigator’s area.Presented results may be helpful for the CT aerodynamic design optimization, particularly, for perspective hybrid type CTs.

  5. Prediction of aerodynamic performance for MEXICO rotor

    DEFF Research Database (Denmark)

    Hong, Zedong; Yang, Hua; Xu, Haoran

    2013-01-01

    The aerodynamic performance of the MEXICO (Model EXperiments In Controlled cOnditions) rotor at five tunnel wind speeds is predicted by making use of BEM and CFD methods, respectively, using commercial MATLAB and CFD software. Due to the pressure differences on both sides of the blade, the tip...... the reliability of the MEXICO data. Second, the SST turbulence model can better capture the flow separation on the blade and has high aerodynamic performance prediction accuracy for a horizontal axis wind turbine in axial inflow conditions. Finally, the comparisons of the axial and tangential forces as well...

  6. Compressor performance aerodynamics for the user

    CERN Document Server

    Gresh, Theodore

    2001-01-01

    Compressor Performance is a reference book and CD-ROM for compressor design engineers and compressor maintenance engineers, as well as engineering students. The book covers the full spectrum of information needed for an individual to select, operate, test and maintain axial or centrifugal compressors. It includes basic aerodynamic theory to provide the user with the ""how's"" and ""why's"" of compressor design. Maintenance engineers will especially appreciate the troubleshooting guidelines offered. Includes many example problems and reference data such as gas propert

  7. Influence of ribs on train aerodynamic performances

    Institute of Scientific and Technical Information of China (English)

    MIAO Xiu-juan; GAO Guang-jun

    2015-01-01

    The influence of ribs on the train aerodynamic performance was computed using detached eddy simulation (DES), and the transient iteration was solved by the dual-time step lower-upper symmetric Gauss-Seidel (LU-SGS) method. The results show that the ribs installed on the roof have a great effect on the train aerodynamic performance. Compared with trains without ribs, the lift force coefficient of the train with convex ribs changes from negative to positive, while the side force coefficient increases by 110% and 88%, respectively. Due to the combined effect of the lift force and side force, the overturning moment of the train with convex ribs and cutting ribs increases by 140% and 106%, respectively. There is larger negative pressure on the roof of the train without ribs than that with ribs. The ribs on the train would disturb the flow structure and contribute to the air separation, so the separation starts from the roof, while there is no air separation on the roof of the train without ribs. The ribs can also slow down the flow speed above the roof and make the air easily sucked back to the train surface. The vortices at the leeward side of the train without ribs are small and messy compared with those of the train with convex or cutting ribs.

  8. Advanced turbine cooling, heat transfer, and aerodynamic studies

    Energy Technology Data Exchange (ETDEWEB)

    Je-Chin Han; Schobeiri, M.T. [Texas A& M Univ., College Station, TX (United States)

    1995-10-01

    The contractual work is in three parts: Part I - Effect of rotation on enhanced cooling passage heat transfer, Part II - Effect on Thermal Barrier Coating (TBC) spallation on surface heat transfer, and Part III - Effect of surface roughness and trailing edge ejection on turbine efficiency under unsteady flow conditions. Each section of this paper has been divided into three parts to individually accommodate each part. Part III is further divided into Parts IIIa and IIIb.

  9. High Performance Torso Cooling Garment

    Science.gov (United States)

    Conger, Bruce; Makinen, Janice

    2016-01-01

    The concept proposed in this paper is to improve thermal efficiencies of the liquid cooling and ventilation garment (LCVG) in the torso area, which could facilitate removal of LCVG tubing from the arms and legs, thereby increasing suited crew member mobility. EVA space suit mobility in micro-gravity is challenging, and it becomes even more challenging in the gravity of Mars. By using shaped water tubes that greatly increase the contact area with the skin in the torso region of the body, the heat transfer efficiency can be increased. This increase in efficiency could provide the required liquid cooling via torso tubing only; no arm or leg LCVG tubing would be required. Benefits of this approach include increased crewmember mobility, enhanced evaporation cooling, increased comfort during Mars EVA tasks, and easing of the overly dry condition in the helmet associated with the Advanced Extravehicular Mobility Unit (EMU) ventilation loop currently under development. This report describes analysis and test activities performed to evaluate the potential improvements to the thermal performance of the LCVG. Analyses evaluated potential tube shapes for improving the thermal performance of the LCVG. The analysis results fed into the selection of flat flow strips to improve thermal contact with the skin of the suited test subject. Testing of small segments was performed to compare thermal performance of the tubing approach of the current LCVG to the flat flow strips proposed as the new concept. Results of the testing is presented along with recommendations for future development of this new concept.

  10. Aerodynamic performances of cruise missile flying above local terrain

    Science.gov (United States)

    Ahmad, A.; Saad, M. R.; Che Idris, A.; Rahman, M. R. A.; Sujipto, S.

    2016-10-01

    Cruise missile can be classified as a smart bomb and also Unmanned Aerial Vehicle (UAV) due to its ability to move and manoeuvre by itself without a pilot. Cruise missile flies in constant velocity in cruising stage. Malaysia is one of the consumers of cruise missiles that are imported from other nations, which can have distinct geographic factors including their local terrains compared to Malaysia. Some of the aerodynamic performances of missile such as drag and lift coefficients can be affected by the local geographic conditions in Malaysia, which is different from the origin nation. Therefore, a detailed study must be done to get aerodynamic performance of cruise missiles that operate in Malaysia. The effect of aerodynamic angles such as angle of attack and side slip can be used to investigate the aerodynamic performances of cruise missile. Hence, subsonic wind tunnel testings were conducted to obtain the aerodynamic performances of the missile at various angle of attack and sideslip angles. Smoke visualization was also performed to visualize the behaviour of flow separation. The optimum angle of attack found was at α=21° and side slip, β=10° for optimum pitching and yawing motion of cruise missile.

  11. A comparative study on showerhead cooling performance

    Energy Technology Data Exchange (ETDEWEB)

    Falcoz, C.; Ott, P. [Ecole Polytechnique Federale de Lausanne (EPFL), Laboratoire de Thermique Appliquee et de Turbomachines (LTT), 1015 Lausanne (Switzerland); Weigand, B. [Institut fuer Thermodynamik der Luft- und Raumfahrt (ITLR), Stuttgart University, Pfaffenwaldring 31, 70569 Stuttgart (Germany)

    2006-04-15

    In modern gas turbines, the turbine airfoil leading edge is currently protected from the hot gas by specific film cooling schemes, so called showerhead cooling. The present paper shows a numerical study of different showerhead cooling geometries. The 3D finite element program ABAQUS as well as a 2D finite element program have been employed to predict the showerhead cooling performance. In the numerical calculations, the different cooling effects and their contribution to the total showerhead cooling performance have been investigated separately. From the numerical calculations a simple method has been derived which enables the prediction of the performance of a 3D showerhead cooling scheme by simple 2D computations. Experimental investigations on showerhead cooling have been presented in a companion paper [C. Falcoz, B. Weigand, P. Ott, Experimental investigations on showerhead cooling on a blunt body. Int. J. Heat Mass Transfer, in press. r publication]. (author)

  12. Cooling Performance of an Impingement Cooling Device Combined with Pins

    Institute of Scientific and Technical Information of China (English)

    Dongliang QUAN; Songling LIU; Jianghai LI; Gaowen LIU

    2005-01-01

    Experimental study and one dimensional model analysis were conducted to investigate cooling performance of an integrated impingement and pin fin cooling device. A typical configuration specimen was made and tested in a large scale low speed closed-looped wind tunnel. Detailed two-dimensional contour maps of the temperature and cooling effectiveness were obtained for different pressure ratios and therefore different coolant flow-rates through the tested specimen. The experimental results showed that very high cooling effectiveness can be achieved by this cooling device with relatively small amount of coolant flow. Based on the theory of transpiration cooling in porous material, a one dimensional heat transfer model was established to analyze the effect of various parameters on cooling effectiveness. It was found from this model that the variation of heat transfer on the gas side, including heat transfer coefficient and film cooling effectiveness, of the specimen created much more effect on its cooling effectiveness than that of the coolant side. The predictions of the one-dimensional mode were compared and agreed well with the experimental data.

  13. Aerodynamics and flight performance of flapping wing micro air vehicles

    Science.gov (United States)

    Silin, Dmytro

    Research efforts in this dissertation address aerodynamics and flight performance of flapping wing aircraft (ornithopters). Flapping wing aerodynamics was studied for various wing sizes, flapping frequencies, airspeeds, and angles of attack. Tested wings possessed both camber and dihedral. Experimental results were analyzed in the framework of momentum theory. Aerodynamic coefficients and Reynolds number are defined using a reference velocity as a vector sum of a freestream velocity and a strokeaveraged wingtip velocity. No abrupt stall was observed in flapping wings for the angle of attack up to vertical. If was found that in the presence of a freestream lift of a flapping wing in vertical position is higher than the propulsive thrust. Camber and dihedral increased both lift and thrust. Lift-curve slope, and maximum lift coefficient increased with Reynolds number. Performance model of an ornithopter was developed. Parametric studies of steady level flight of ornithopters with, and without a tail were performed. A model was proposed to account for wing-sizing effects during hover. Three micro ornithopter designs were presented. Ornithopter flight testing and data-logging was performed using a telemetry acquisition system, as well as motion capture technology. The ability of ornithopter for a sustained flight and a presence of passive aerodynamic stability were shown. Flight data were compared with performance simulations. Close agreement in terms of airspeed and flapping frequency was observed.

  14. Plasma Aerodynamic Control Effectors for Improved Wind Turbine Performance

    Energy Technology Data Exchange (ETDEWEB)

    Mehul P. Patel; Srikanth Vasudevan; Robert C. Nelson; Thomas C. Corke

    2008-08-01

    Orbital Research Inc is developing an innovative Plasma Aerodynamic Control Effectors (PACE) technology for improved performance of wind turbines. The PACE system is aimed towards the design of "smart" rotor blades to enhance energy capture and reduce aerodynamic loading and noise using flow-control. The PACE system will provide ability to change aerodynamic loads and pitch distribution across the wind turbine blade without any moving surfaces. Additional benefits of the PACE system include reduced blade structure weight and complexity that should translate into a substantially reduced initial cost. During the Phase I program, the ORI-UND Team demonstrated (proof-of-concept) performance improvements on select rotor blade designs using PACE concepts. Control of both 2-D and 3-D flows were demonstrated. An analytical study was conducted to estimate control requirements for the PACE system to maintain control during wind gusts. Finally, independent laboratory experiments were conducted to identify promising dielectric materials for the plasma actuator, and to examine environmental effects (water and dust) on the plasma actuator operation. The proposed PACE system will be capable of capturing additional energy, and reducing aerodynamic loading and noise on wind turbines. Supplementary benefits from the PACE system include reduced blade structure weight and complexity that translates into reduced initial capital costs.

  15. Experimental study on the aerodynamic performance of a Savonius rotor

    Energy Technology Data Exchange (ETDEWEB)

    Fujisawa, Nobuyuki; Gotoh, Futoshi (Gunma Univ., Kiryu (Japan). Dept. of Mechanical Engineering)

    1994-08-01

    The aerodynamic performance of a Savonius rotor has been studied by measuring the pressure distributions on the blade surfaces at various rotor angles and tip-speed ratios. It is found that the pressure distributions on the rotating rotor differ remarkably from those on the still rotor especially on the convex side of the advancing blade, where a low pressure region is formed by the moving wall effect of the blade. The torque and power performances, evaluated by integrating the pressure, are in close agreement with those by the direct torque measurement. The drag and side force performance is also studied.

  16. Effect of Moving Surface on NACA 63218 Aerodynamic Performance

    Directory of Open Access Journals (Sweden)

    Yahiaoui Tayeb

    2015-01-01

    Full Text Available The main subject of this work is the numerical study control of flow separation on a NACA 63218 airfoil by using moving surface. Different numerical cases are considered: the first one is the numerical simulation of non-modified airfoil NACA 63218 according at different angle of attack and the second one a set of moving cylinder is placed on leading edge of the airfoil. The rotational velocity of the cylinder is varied to establish the effect of momentum injection on modified airfoil aerodynamic performances. The turbulence is modeled by two equations k-epsilon model.

  17. An aerodynamic performance analysis of a perforated wind turbine blade

    Science.gov (United States)

    Didane, D. H.; Mohd, S.; Subari, Z.; Rosly, N.; Ghafir, M. F. Abdul; Mohd Masrom, M. F.

    2016-11-01

    Wind power is one of the important renewable energy sources. Currently, many researches are focusing on improving the aerodynamic performance of wind turbine blades through simulations and wind tunnel testing. In the present study, the aerodynamic performance of the perforated Eqwin blade (shell type blade) is investigated by using numerical simulation. Three types of slots namely circular, horizontal rectangular and vertical rectangular were evaluated. It was found that the optimum angle of attack for a perforated shell type blade was 12° with maximum Cl/Cd value of 6.420. In general, for all the perforated blade cases, Cl/Cd tended to decrease as the slot size increased except for the circular slot with 5 mm diameter. This was due to the disturbance of the airflow in lower side region which passed through the bigger slot size. Among the modified slots; the circular slot with diameter of 5 mm would be the best slot configuration that can be considered for blade fabrication. The Cl/Cd obtained was 6.46 which is about 5% more than the value of the reference blade. Moreover, the introduced slot would also reduce the overall weight of the blade by 1.3%.

  18. Aerodynamic performance prediction of Darrieus-type wind turbines

    Directory of Open Access Journals (Sweden)

    Ion NILĂ

    2010-06-01

    Full Text Available The prediction of Darrieus wind turbine aerodynamic performances provides the necessarydesign and operational data base related to the wind potential. In this sense it provides the type ofturbine suitable to the area where it is to be installed. Two calculation methods are analyzed for arotor with straight blades. The first one is a global method that allows an assessment of the turbinenominal power by a brief calculation. This method leads to an overestimation of performances. Thesecond is the calculation method of the gust factor and momentum which deals with the pale as beingcomposed of different elements that don’t influence each other. This method, developed based on thetheory of the turbine blades, leads to values close to the statistical data obtained experimentally. Thevalues obtained by the calculation method of gust factor - momentum led to the concept of a Darrieusturbine, which will be tested for different wind values in the INCAS subsonic wind tunnel.

  19. The effect of pre-cooling intensity on cooling efficiency and exercise performance

    NARCIS (Netherlands)

    Bogerd, N.; Perret, C.; Bogerd, C.P.; Rossi, R.M.; Daanen, H.A.M.

    2010-01-01

    Although pre-cooling is known to enhance exercise performance, the optimal cooling intensity is unknown. We hypothesized that mild cooling opposed to strong cooling circumvents skin vasoconstriction and thermogenesis, and thus improves cooling efficiency reflected in improved time to exhaustion. Eig

  20. A method for calculation of forces acting on air cooled gas turbine blades based on the aerodynamic theory

    Directory of Open Access Journals (Sweden)

    Grković Vojin R.

    2013-01-01

    Full Text Available The paper presents the mathematical model and the procedure for calculation of the resultant force acting on the air cooled gas turbine blade(s based on the aerodynamic theory and computation of the circulation around the blade profile. In the conducted analysis was examined the influence of the cooling air mass flow expressed through the cooling air flow parameter λc, as well as, the values of the inlet and outlet angles β1 and β2, on the magnitude of the tangential and axial forces. The procedure and analysis were exemplified by the calculation of the tangential and axial forces magnitudes. [Projekat Ministarstva nauke Republike Srbije: Development and building the demonstrative facility for combined heat and power with gasification

  1. Fan Noise Source Diagnostic Test: Rotor Alone Aerodynamic Performance Results

    Science.gov (United States)

    Hughes, Christopher E.; Jeracki, Robert J.; Woodward, Richard P.; Miller, Christopher J.

    2005-01-01

    The aerodynamic performance of an isolated fan or rotor alone model was measured in the NASA Glenn Research Center 9- by 15- Foot Low Speed Wind Tunnel as part of the Fan Broadband Source Diagnostic Test conducted at NASA Glenn. The Source Diagnostic Test was conducted to identify the noise sources within a wind tunnel scale model of a turbofan engine and quantify their contribution to the overall system noise level. The fan was part of a 1/5th scale model representation of the bypass stage of a current technology turbofan engine. For the rotor alone testing, the fan and nacelle, including the inlet, external cowl, and fixed area fan exit nozzle, were modeled in the test hardware; the internal outlet guide vanes located behind the fan were removed. Without the outlet guide vanes, the velocity at the nozzle exit changes significantly, thereby affecting the fan performance. As part of the investigation, variations in the fan nozzle area were tested in order to match as closely as possible the rotor alone performance with the fan performance obtained with the outlet guide vanes installed. The fan operating performance was determined using fixed pressure/temperature combination rakes and the corrected weight flow. The performance results indicate that a suitable nozzle exit was achieved to be able to closely match the rotor alone and fan/outlet guide vane configuration performance on the sea level operating line. A small shift in the slope of the sea level operating line was measured, which resulted in a slightly higher rotor alone fan pressure ratio at take-off conditions, matched fan performance at cutback conditions, and a slightly lower rotor alone fan pressure ratio at approach conditions. However, the small differences in fan performance at all fan conditions were considered too small to affect the fan acoustic performance.

  2. PERFORMANCE ANALYSIS OF MECHANICAL DRAFT COOLING TOWER

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S; Alfred Garrett, A; James02 Bollinger, J; Larry Koffman, L

    2009-02-10

    Industrial processes use mechanical draft cooling towers (MDCT's) to dissipate waste heat by transferring heat from water to air via evaporative cooling, which causes air humidification. The Savannah River Site (SRS) has cross-flow and counter-current MDCT's consisting of four independent compartments called cells. Each cell has its own fan to help maximize heat transfer between ambient air and circulated water. The primary objective of the work is to simulate the cooling tower performance for the counter-current cooling tower and to conduct a parametric study under different fan speeds and ambient air conditions. The Savannah River National Laboratory (SRNL) developed a computational fluid dynamics (CFD) model and performed the benchmarking analysis against the integral measurement results to accomplish the objective. The model uses three-dimensional steady-state momentum, continuity equations, air-vapor species balance equation, and two-equation turbulence as the basic governing equations. It was assumed that vapor phase is always transported by the continuous air phase with no slip velocity. In this case, water droplet component was considered as discrete phase for the interfacial heat and mass transfer via Lagrangian approach. Thus, the air-vapor mixture model with discrete water droplet phase is used for the analysis. A series of parametric calculations was performed to investigate the impact of wind speeds and ambient conditions on the thermal performance of the cooling tower when fans were operating and when they were turned off. The model was also benchmarked against the literature data and the SRS integral test results for key parameters such as air temperature and humidity at the tower exit and water temperature for given ambient conditions. Detailed results will be published here.

  3. CSCM Navier-Stokes thermal/aerodynamic analysis of hypersonic nozzle flows with slot injection and wall cooling

    Science.gov (United States)

    Codding, William H.; Lombard, C. K.; Yang, J. Y.

    1988-01-01

    The Conservative Supra-Characteristic Method (CSCM) Navier-Stokes solver is applied to ascertain the problems inherent in the design of a nominal Mach 14 nozzle for NASA-Ames' 3.5-ft Hypersonic Wind Tunnel; attention is given to the effects of boundary layer cooling systems on the aerodynamic redesign of the nozzle throat region. Complete nozzle flowfields are calculated with and without slot injection of either hot or cold fluid into the boundary layer just upstream of the throat, as well as with alternatively adiabatic and cold walls. The CSCM method is capable of resolving subtle differences in the flows.

  4. Performance of streamlined bridge decks in relation to the aerodynamics of a flat plate

    DEFF Research Database (Denmark)

    Larose, Guy; Livesey, Flora M.

    1997-01-01

    The aerodynamics of three modern bridge decks are compared to the aerodynamics of a 16:1 flat plate. The comparisons are made on the basis of the analytical evaluation of the performance of each cross-section to the buffeting action of the wind. In general, the closed-box girders studied in this ...... in this paper showed buffeting responses similar to a flat plate with the exception of the multi-box girder which performed much better aerodynamically.......The aerodynamics of three modern bridge decks are compared to the aerodynamics of a 16:1 flat plate. The comparisons are made on the basis of the analytical evaluation of the performance of each cross-section to the buffeting action of the wind. In general, the closed-box girders studied...

  5. Performance of Air-cooled Engine Cylinders Using Blower Cooling

    Science.gov (United States)

    Schey, Oscar W; Ellerbrock, Herman H , Jr

    1936-01-01

    An investigation was made to obtain information on the minimum quantity of air and power required to cool conventional air cooled cylinders at various operating conditions when using a blower. The results of these tests show that the minimum power required for satisfactory cooling with an overall blower efficiency of 100 percent varied from 2 to 6 percent of the engine power depending on the operating conditions. The shape of the jacket had a large effect on the cylinder temperatures. Increasing the air speed over the front of the cylinder by keeping the greater part of the circumference of the cylinder covered by the jacket reduced the temperatures over the entire cylinder.

  6. Theoretical analysis of the performance of different cooling strategies with the concept of cool exergy

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2016-01-01

    The whole chains of exergy flows for different cooling systems were compared. The effects of cooling demand (internal vs. external solar shading), space cooling method (floor cooling vs. air cooling with ventilation system), and the availability of a nearby natural heat sink (intake air for the v......The whole chains of exergy flows for different cooling systems were compared. The effects of cooling demand (internal vs. external solar shading), space cooling method (floor cooling vs. air cooling with ventilation system), and the availability of a nearby natural heat sink (intake air......-water, etc.) and indoor terminal units, only with a minimized demand. The water-based floor cooling system performed better than the air-based cooling system; when an air-to-water heat pump was used as the cooling source, the required exergy input was 28% smaller for the floor cooling system. The auxiliary...... exergy input of air-based systems was significantly larger than the water-based systems. The use of available cool exergy in the crawl-space resulted in 54% and 29% smaller exergy input to the power plant for the air-based and water-based cooling systems, respectively. For floor cooling, the exergy input...

  7. Effect of sidewall configurations on aerodynamic performance of supersonic air-intake

    OpenAIRE

    Watanabe, Yasushi; Murakami, Akira; Fujiwara, Hitoshi; 渡辺 安; 村上 哲; 藤原 仁志

    2004-01-01

    The effects of sidewall configurations on the aerodynamic performance of two dimensional external compression supersonic air-intakes were investigated experimentally and numerically. The aerodynamic performance for various yaw angles and ramp angles was obtained by wind tunnel tests performed in the Mach number range of 1.5 to 2.0. It was found that the major advantage of an air-intake with a larger sidewall configuration is its wider stable range in subcritical operation. On the other hand, ...

  8. THERMAL AND AERODYNAMIC PERFORMANCES OF THE SUPERSONIC MOTION

    Directory of Open Access Journals (Sweden)

    Dejan P Ninković

    2010-01-01

    Full Text Available Generally speaking, Mach number of 4 can be taken as a boundary value for transition from conditions for supersonic, into the area of hypersonic flow, distinguishing two areas: area of supersonic in which the effects of the aerodynamic heating can be neglected and the area of hypersonic, in which the thermal effects become dominant. This paper presents the effects in static and dynamic areas, as well as presentation of G.R.O.M. software for determination of the values of aerodynamic derivatives, which was developed on the basis of linearized theory of supersonic flow. Validation of developed software was carried out through different types of testing, proving its usefulness for engineering practice in the area of supersonic wing aerodynamic loading calculations, even at high Mach numbers, with dominant thermal effects.

  9. Aerodynamic Performance and Turbulence Measurements in a Turbine Vane Cascade

    Science.gov (United States)

    Boyle, Robert J.; Lucci, Barbara L.; Senyitko, Richard G.

    2002-01-01

    Turbine vane aerodynamics were measured in a three vane linear cascade. Surface pressures and blade row losses were obtained over a range of Reynolds and Mach number for three levels of turbulence. Comparisons are made with predictions using a quasi-3D Navier-Stokes analysis. Turbulence intensity measurement were made upstream and downstream of the vane. The purpose of the downstream measurements was to determine how the turbulence was affected by the strong contraction through 75 deg turning.

  10. Thermotechnical performance of an air-cooled tuyere with air cooling channels in series

    Science.gov (United States)

    Shen, Yuansheng; Zhou, Yuanyuan; Zhu, Tao; Duan, Guangbin

    2017-01-01

    To reduce the cooling air consumption for an air-cooled tuyere, an air-cooled tuyere with air cooling channels in series is developed based on several hypotheses, i.e., a transparent medium in the blast furnace, among others, and the related mathematical models are introduced and developed. Referring to the data from a BF site, the thermotechnical computation for the air-cooled tuyere was performed, and the results show that when the temperature of the inlet cooling air increases, the temperatures for the outlet cooling air, the outer surface of the tuyere, the walls of the air cooling channels and the center channel as well as the heat going into the center channel increase, but the heat absorbed by the cooling air flowing through the air cooling channels decreases. When the cooling air flow rate under the standard state increases, the physical parameters mentioned above change in an opposite directions. Compared to a water-cooled tuyere, the energy savings for an air-cooled tuyere are more than 0.23 kg/min standard coal.

  11. Aerodynamic performance of a vibrating piezoelectric fan under varied operational conditions

    Science.gov (United States)

    Stafford, J.; Jeffers, N.

    2014-07-01

    This paper experimentally examines the bulk aerodynamic performance of a vibrating fan operating in the first mode of vibration. The influence of operating condition on the local velocity field has also been investigated to understand the flow distribution at the exit region and determine the stalling condition for vibrating fans. Fan motion has been generated and controlled using a piezoelectric ceramic attached to a stainless steel cantilever. The frequency and amplitude at resonance were 109.4 Hz and 12.5 mm, respectively. A test facility has been developed to measure the pressure-flow characteristics of the vibrating fan and simultaneously conduct local velocity field measurements using particle image velocimetry. The results demonstrate the impact of system characteristics on the local velocity field. High momentum regions generated due to the oscillating motion exist with a component direction that is tangent to the blade at maximum displacement. These high velocity zones are significantly affected by increasing impedance while flow reversal is a dominant feature at maximum pressure rise. The findings outlined provide useful information for design of thermal management solutions that may incorporate this air cooling approach.

  12. Performance Analysis of XCPC Powered Solar Cooling Demonstration Project

    Science.gov (United States)

    Widyolar, Bennett K.

    A solar thermal cooling system using novel non-tracking External Compound Parabolic Concentrators (XCPC) has been built at the University of California, Merced and operated for two cooling seasons. Its performance in providing power for space cooling has been analyzed. This solar cooling system is comprised of 53.3 m2 of XCPC trough collectors which are used to power a 23 kW double effect (LiBr) absorption chiller. This is the first system that combines both XCPC and absorption chilling technologies. Performance of the system was measured in both sunny and cloudy conditions, with both clean and dirty collectors. It was found that these collectors are well suited at providing thermal power to drive absorption cooling systems and that both the coinciding of available thermal power with cooling demand and the simplicity of the XCPC collectors compared to other solar thermal collectors makes them a highly attractive candidate for cooling projects.

  13. Numerical investigation of geometric parameter effects on the aerodynamic performance of a Bladeless fan

    OpenAIRE

    Mohammad Jafari; Hossein Afshin; Bijan Farhanieh; Atta Sojoudi

    2016-01-01

    Aerodynamic performance of a Bladeless fan is numerically investigated considering the effect of five geometric parameters. Airflow through this fan was analyzed by simulating a Bladeless fan within a 2 m × 2 m × 4 m room. Analysis of the flow field inside the fan and the evaluation of its performance were obtained by solving conservations of mass and momentum equations for the aerodynamic investigations. In order to design the Bladeless fan an Eppler 473 airfoil profile was used as the cross...

  14. Numerical study on the aerodynamic performance and safe running of high-speed trains in sandstorms

    Institute of Scientific and Technical Information of China (English)

    Hong-bing XIONG; Wen-guang YU; Da-wei CHEN; Xue-ming SHAO

    2011-01-01

    The influence of sandstorms on train aerodynamic performance and safe running was studied in response to the frequent occurrence of sandstorm weather in north China.An Eulerian two-phase model in the computational fluid dynamic (CFD) software FLUENT,validated with published data,was used to solve the gas-solid multiphase flow of a sandstorm around a train.The train aerodynamic performance under different sandstorm levels and no sand conditions was then simulated.Results showed that in sandstorm weather,the drag,lift,side forces and overturning moment increase by variable degrees.Based on a numerical analysis of aerodynamic characteristics,an equation of train stability was also derived using the theory of moment balance from the view of dynamics.A recommended speed limit of a train under different sandstorm levels was calculated based on the stability analysis.

  15. Performance testing of engineered corium cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Lomperski, S., E-mail: lomperski@anl.gov [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439-4840 (United States); Farmer, M.T. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439-4840 (United States)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Experiments tested two engineered corium cooling systems. Black-Right-Pointing-Pointer The systems passively inject water into corium from below. Black-Right-Pointing-Pointer These systems cool corium much faster than top flooding. - Abstract: The coolability of ex-vessel core debris continues to be an issue of concern in the realm of light water reactor safety. Extensive research into corium/concrete interaction phenomena has been unable to establish the certainty of melt quench and stabilization within the containment boundary for all credible cases of cooling restricted to top flooding. As a result, there has been continuing interest in engineered systems that can augment cooling. This paper describes the testing of two passive cooling concepts that inject water into corium from below via nozzles embedded within the basemat: one with porous concrete nozzles and the other with a type of composite nozzle. The latter supplements water injection with noncondensable gas to stabilize flow and suppress vapor explosions. Each test involved a 136 kg melt composed of 56/23/14 wt% UO{sub 2}/ZrO{sub 2}/siliceous concrete at an initial depth of 30 cm. The setup with the porous concrete nozzles successfully injected water into the melt at heads as low as 2.3 m. The composite nozzle test was partially successful, with three nozzles delivering coolant while a fourth was damaged by the melt and failed to inject water. The melts cooled twice as fast as similar ones tested in a top flooding configuration. These experiments confirmed earlier work at Forschungszentrum Karlsruhe and elsewhere indicating that cooling via bottom water injection is a particularly effective method for quenching ex-vessel corium melts.

  16. Aerodynamic performance of winglets covering the tip gap inlet in a turbine cascade

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Woo, E-mail: swlee@kumoh.ac.kr [Department of Mechanical Engineering, Kumoh National Institute of Technology, 1 Yangho-dong, Gumi, Gyeongbuk 730-701 (Korea, Republic of); Kim, Seon Ung; Kim, Kyoung Hoon [Department of Mechanical Engineering, Kumoh National Institute of Technology, 1 Yangho-dong, Gumi, Gyeongbuk 730-701 (Korea, Republic of)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer We test aerodynamics of PS and LEPS winglets for three winglet widths. Black-Right-Pointing-Pointer PS winglet reduces tip leakage loss but increases loss in the passage vortex region. Black-Right-Pointing-Pointer Mass-averaged loss reductions by PS and LEPS winglets are marginal. Black-Right-Pointing-Pointer The loss reductions are much smaller than that by a cavity squealer tip. - Abstract: The aerodynamic performance of two different kinds of winglets covering the tip gap inlet of a plane tip, a 'pressure-side' (PS) winglet and a 'leading-edge and pressure-side' (LEPS) winglet, has been investigated in a turbine cascade. For a tip gap height-to-chord ratio of h/c = 2.0%, their width-to-pitch ratio is changed to be w/p = 2.64, 5.28, and 10.55%. The PS winglet reduces aerodynamic loss in the tip leakage vortex region as well as in an area downstream of the winglet-pressure surface corner, whereas it increases aerodynamic loss in the central area of the passage vortex region. The additional leading-edge winglet portion of the LEPS winglet reduces aerodynamic loss considerably on the casing wall side of the passage vortex region but delivers a noticeable aerodynamic loss increase on its mid-span side. These local trends are deepened with increasing w/p. However, the mass-averaged aerodynamic loss reductions by installing the PS and LEPS winglets in comparison with the baseline no winglet data are only marginal even for w/p = 10.55% and found much smaller than that by employing a cavity squealer tip.

  17. Analysis and Improvement of Aerodynamic Performance of Straight Bladed Vertical Axis Wind Turbines

    Science.gov (United States)

    Ahmadi-Baloutaki, Mojtaba

    Vertical axis wind turbines (VAWTs) with straight blades are attractive for their relatively simple structure and aerodynamic performance. Their commercialization, however, still encounters many challenges. A series of studies were conducted in the current research to improve the VAWTs design and enhance their aerodynamic performance. First, an efficient design methodology built on an existing analytical approach is presented to formulate the design parameters influencing a straight bladed-VAWT (SB-VAWT) aerodynamic performance and determine the optimal range of these parameters for prototype construction. This work was followed by a series of studies to collectively investigate the role of external turbulence on the SB-VAWTs operation. The external free-stream turbulence is known as one of the most important factors influencing VAWTs since this type of turbines is mainly considered for urban applications where the wind turbulence is of great significance. Initially, two sets of wind tunnel testing were conducted to study the variation of aerodynamic performance of a SB-VAWT's blade under turbulent flows, in two major stationary configurations, namely two- and three-dimensional flows. Turbulent flows generated in the wind tunnel were quasi-isotropic having uniform mean flow profiles, free of any wind shear effects. Aerodynamic force measurements demonstrated that the free-stream turbulence improves the blade aerodynamic performance in stall and post-stall regions by delaying the stall and increasing the lift-to-drag ratio. After these studies, a SB-VAWT model was tested in the wind tunnel under the same type of turbulent flows. The turbine power output was substantially increased in the presence of the grid turbulence at the same wind speeds, while the increase in turbine power coefficient due to the effect of grid turbulence was small at the same tip speed ratios. The final section presents an experimental study on the aerodynamic interaction of VAWTs in arrays

  18. Aerodynamic and Performance Measurements on a SWT-2.3-101 Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Medina, P.; Singh, M.; Johansen, J.; Jove, A.R.; Machefaux, E.; Fingersh, L. J.; Schreck, S.

    2011-10-01

    This paper provides an overview of a detailed wind turbine field experiment being conducted at NREL under U.S. Department of Energy sponsorship. The purpose of the experiment is to obtain knowledge about the aerodynamics, performance, noise emission and structural characteristics of the Siemens SWT-2.3-101 wind turbine.

  19. Influence of wing kinematics on aerodynamic performance in hovering insect flight

    NARCIS (Netherlands)

    Bos, F.M.; Lentink, D.; Van Oudheusden, B.W.; Bijl, H.

    2007-01-01

    The influence of different wing kinematic models on the aerodynamic performance of a hovering insect is investigated by means of two-dimensional time-dependent Navier–Stokes simulations. For this, simplified models are compared with averaged representations of the hovering fruit fly wing kinematics.

  20. Influence of wing kinematics on aerodynamic performance in hovering insect flight

    NARCIS (Netherlands)

    Bos, F.M.; Lentink, D.; Oudheusden, van B.W.; Bijl, H.

    2008-01-01

    The influence of different wing kinematic models on the aerodynamic performance of a hovering insect is investigated by means of two-dimensional time-dependent Navier¿Stokes simulations. For this, simplified models are compared with averaged representations of the hovering fruit fly wing kinematics.

  1. Comparing aerodynamic efficiency in birds and bats suggests better flight performance in birds.

    Science.gov (United States)

    Muijres, Florian T; Johansson, L Christoffer; Bowlin, Melissa S; Winter, York; Hedenström, Anders

    2012-01-01

    Flight is one of the energetically most costly activities in the animal kingdom, suggesting that natural selection should work to optimize flight performance. The similar size and flight speed of birds and bats may therefore suggest convergent aerodynamic performance; alternatively, flight performance could be restricted by phylogenetic constraints. We test which of these scenarios fit to two measures of aerodynamic flight efficiency in two passerine bird species and two New World leaf-nosed bat species. Using time-resolved particle image velocimetry measurements of the wake of the animals flying in a wind tunnel, we derived the span efficiency, a metric for the efficiency of generating lift, and the lift-to-drag ratio, a metric for mechanical energetic flight efficiency. We show that the birds significantly outperform the bats in both metrics, which we ascribe to variation in aerodynamic function of body and wing upstroke: Bird bodies generated relatively more lift than bat bodies, resulting in a more uniform spanwise lift distribution and higher span efficiency. A likely explanation would be that the bat ears and nose leaf, associated with echolocation, disturb the flow over the body. During the upstroke, the birds retract their wings to make them aerodynamically inactive, while the membranous bat wings generate thrust and negative lift. Despite the differences in performance, the wake morphology of both birds and bats resemble the optimal wake for their respective lift-to-drag ratio regimes. This suggests that evolution has optimized performance relative to the respective conditions of birds and bats, but that maximum performance is possibly limited by phylogenetic constraints. Although ecological differences between birds and bats are subjected to many conspiring variables, the different aerodynamic flight efficiency for the bird and bat species studied here may help explain why birds typically fly faster, migrate more frequently and migrate longer distances

  2. Comparing aerodynamic efficiency in birds and bats suggests better flight performance in birds.

    Directory of Open Access Journals (Sweden)

    Florian T Muijres

    Full Text Available Flight is one of the energetically most costly activities in the animal kingdom, suggesting that natural selection should work to optimize flight performance. The similar size and flight speed of birds and bats may therefore suggest convergent aerodynamic performance; alternatively, flight performance could be restricted by phylogenetic constraints. We test which of these scenarios fit to two measures of aerodynamic flight efficiency in two passerine bird species and two New World leaf-nosed bat species. Using time-resolved particle image velocimetry measurements of the wake of the animals flying in a wind tunnel, we derived the span efficiency, a metric for the efficiency of generating lift, and the lift-to-drag ratio, a metric for mechanical energetic flight efficiency. We show that the birds significantly outperform the bats in both metrics, which we ascribe to variation in aerodynamic function of body and wing upstroke: Bird bodies generated relatively more lift than bat bodies, resulting in a more uniform spanwise lift distribution and higher span efficiency. A likely explanation would be that the bat ears and nose leaf, associated with echolocation, disturb the flow over the body. During the upstroke, the birds retract their wings to make them aerodynamically inactive, while the membranous bat wings generate thrust and negative lift. Despite the differences in performance, the wake morphology of both birds and bats resemble the optimal wake for their respective lift-to-drag ratio regimes. This suggests that evolution has optimized performance relative to the respective conditions of birds and bats, but that maximum performance is possibly limited by phylogenetic constraints. Although ecological differences between birds and bats are subjected to many conspiring variables, the different aerodynamic flight efficiency for the bird and bat species studied here may help explain why birds typically fly faster, migrate more frequently and migrate

  3. Inlet Flux Influence to Aerodynamic Performance of Steam Turbine Vane Cascade

    OpenAIRE

    Feng Zi-Ming; Ding Huanhuan; Li Chunhong; Xu Ping

    2014-01-01

    In order to improve the aerodynamic performance and the performance of off-design working condition, it is necessary to research the inlet flow rate influence to overall performance of steam turbine. This study uses CFD technology to numerical simulation the flow field of nozzle cascades passage at 80, 100, 120% flow rate, respectively. The simulation results indicates that the various flow loss of nozzle have a little change at 100% design working condition, have decreased at 80% design work...

  4. Aerodynamic loading distribution effects on the overall performance of ultra-high-lift LP turbine cascades

    Science.gov (United States)

    Berrino, M.; Satta, F.; Simoni, D.; Ubaldi, M.; Zunino, P.; Bertini, F.

    2014-02-01

    The present paper reports the results of an experimental investigation aimed at comparing aerodynamic performance of three low-pressure turbine cascades for several Reynolds numbers under steady and unsteady inflows. This study is focused on finding design criteria useful to reduce both profile and secondary losses in the aero-engine LP turbine for the different flight conditions. The baseline blade cascade, characterized by a standard aerodynamic loading (Zw=1.03), has been compared with two Ultra-High-Lift profiles with the same Zweifel number (Zw=1.3 for both cascades), but different velocity peak positions, leading to front and mid-loaded blade cascade configurations. The aerodynamic flow fields downstream of the cascades have been experimentally investigated for Reynolds numbers in the range 70000plane downstream of the cascade for both inflow conditions. The analysis of the results allows the evaluation of the aerodynamic performance of the blade cascades in terms of profile and secondary losses and the understanding of the effects of loading distribution and Zweifel number on secondary flows. When operating under unsteady inflow, contrarily to the steady case, the mid-loaded cascade has been found to be characterized by the lowest profile and secondary losses, making it the most attractive solution for the design of blades working in real conditions where unsteady inflow effects are present.

  5. Numerical Investigation of Aerodynamic Performance and Loads of a Novel Dual Rotor Wind Turbine

    Directory of Open Access Journals (Sweden)

    Behnam Moghadassian

    2016-07-01

    Full Text Available The objective of this paper is to numerically investigate the effects of the atmospheric boundary layer on the aerodynamic performance and loads of a novel dual-rotor wind turbine (DRWT. Large eddy simulations are carried out with the turbines operating in the atmospheric boundary layer (ABL and in a uniform inflow. Two stability conditions corresponding to neutral and slightly stable atmospheres are investigated. The turbines are modeled using the actuator line method where the rotor blades are modeled as body forces. Comparisons are drawn between the DRWT and a comparable conventional single-rotor wind turbine (SRWT to assess changes in aerodynamic efficiency and loads, as well as wake mixing and momentum and kinetic energy entrainment into the turbine wake layer. The results show that the DRWT improves isolated turbine aerodynamic performance by about 5%–6%. The DRWT also enhances turbulent axial momentum entrainment by about 3.3 %. The highest entrainment is observed in the neutral stability case when the turbulence in the ABL is moderately high. Aerodynamic loads for the DRWT, measured as out-of-plane blade root bending moment, are marginally reduced. Spectral analyses of ABL cases show peaks in unsteady loads at the rotor passing frequency and its harmonics for both rotors of the DRWT.

  6. Electron Cooling Performance at IMP Facility

    CERN Document Server

    Xiaodong, Yang

    2011-01-01

    The ion beam of 58Ni19+ with the energy of 6.39MeV/u was accumulated in the main ring of HIRFL-CSR with the help of electron cooling. The related angle between ion and electron beams in the horizontal and vertical planes was intentionally created by the steering coils in the cooling section after maximized the accumulated ion beam in the ring. The radial electron intensity distribution was changed by the ratio of potentials of grid electrode and anode of the electron gun, the different electron beam profiles were formed from solid to hollow in the experiments. In these conditions, the maximum accumulated ion beam intensity in the 10 seconds was measured, the lifetime of ion beam was measured, simultaneously the momentum spread of the ion beam varying with particle number was measured during the ion beam decay, furthermore, and the power coefficient was derived from these data. In additional, the momentum spread in the case of constant particle number was plotted with the angle and electron beam profile. The o...

  7. Influence of aerodynamics on the heat absorption of convection cooled turbine blades. Final report; Einfluss der Aerodynamik auf die Waermeaufnahme konvektionsgekuehlter Turbinenschaufeln. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Wittig, S.; Schiele, R.; Sieger, K.; Schulz, A.

    1995-12-31

    The objective of this project is the integration of aerodynamic and thermal design in the example of convection cooled turbine blades. For this purpose, in a first section of this project, a boundary-layer numerical method is to be further developed to permit the calculation of heat transfer and fluidic losses of convection cooled cascades. Using this improved calculation method, a prototype aerothermic design of a turbine stator is to be conducted in a second section of the project. Finally, the aerodynamic losses and the heat transfer behavior of the new cascade are to be experimentally investigated to make a design assessment. Due to its decisive importance to aerodynamics and heat transfer in gas-turbine blades, special interest is focused on the process of laminar-turbulent transition. (orig.) [Deutsch] Ziel des Vorhabens ist daher die Zusammenfuehrung der aerodynamischen und thermischen Auslegung am Beispiel konvektionsgekuehlter Turbinenschaufeln. Dazu soll in einem ersten Teil des Vorhabens ein Grenzschichtrechenverfahren weiterentwickelt werden, das die Berechnung des Waermeuebergangs und der stroemungsmechanischen Verluste konvektionsgekuehlter Schaufelgitter ermoeglicht. Mit Hilfe dieses verbesserten Berechnungsverfahrens soll in einem zweiten Teil des Vorhabens eine prototypische aerothermische Auslegung eines Turbinenleitrades durchgefuehrt werden. Schliesslich sollen die aerodynamischen Verluste und das Waermeuebergangsverhalten des neuen Schaufelgitters experimentell untersucht und somit die Auslegung bewertet werden. Aufgrund seiner entscheidenden Bedeutung fuer Aerodynamik und Waermeuebergang an Gasturbinenschaufeln gilt dem Vorgang des laminar-turbulenten Umschlags dabei besonderes Interesse. (orig.)

  8. Flutter Derivatives Identification and Aerodynamic Performance of an Optimized Multibox Bridge Deck

    Directory of Open Access Journals (Sweden)

    Zhida Wang

    2016-01-01

    Full Text Available The bridge deck sections used for long-span suspension bridges have evolved through the years, from the compact box deck girders geometrical configurations to twin-box and three-box bridge decks sections. The latest generation of split and multiple-box bridge decks proved to have better aerodynamic behavior; thus further optimization methods are sought for such geometrical configurations. A new type of multibox bridge deck, consisting of four aerodynamically shaped deck boxes, two side decks for the traffic lanes and two middle decks for the railway traffic, connected between them by stabilizing beams, was tested in the wind tunnel for identifying the flutter derivatives and to verify the aerodynamic performance of the proposed multibox deck. Aerodynamic static force coefficients were measured for the multibox bridge deck model, scaled 1 : 80, for Reynolds numbers up to 5.1 × 105, under angles of attack between −8° and 8°. Iterative Least Squares (ILS method was employed for identifying the flutter derivatives of the multibox bridge deck model, based on the results obtained from the free vibration tests and based on the frequency analysis the critical flutter wind speed for the corresponding prototype of the multibox bridge was estimated at 188 m/s.

  9. Building Integrated Active Flow Control: Improving the Aerodynamic Performance of Tall Buildings Using Fluid-Based Aerodynamic Modification

    Science.gov (United States)

    Menicovich, David

    By 2050 an estimated 9 billion people will inhabit planet earth and almost all the growth in the next 40 years will be in urban areas putting tremendous pressure on creating sustainable cities. The rapid increase in population, rise in land value and decrease in plot sizes in cities around the world positions tall or more importantly slender buildings as the best suited building typology to address the increasingly critical demand for space in this pressing urbanization trend. However, the majority of new tall building urban developments have not followed principles of environmental and/or sustainable design and incentives to innovate, both technological and economic, are urgently required. The biggest climatic challenge to the design, construction and performance of tall buildings is wind sensitivity. This challenge is further emphasized seeing two market driven trends: on one hand as urban population grows, land value rises while plot sizes decrease; on the other, more cost effective modular construction techniques are introducing much lighter tall building structures. The combination of the two suggests a potential increase in the slenderness ratio of tall buildings (typically less than 6:1 but stretching to 20:1 in the near future) where not-so-tall but much lighter buildings will be the bulk of new construction in densely populated cities, providing affordable housing in the face of fast urbanization but also introducing wind sensitivity which was previously the problem of a very limited number of super tall buildings to a much larger number of buildings and communities. The proposed research aims to investigate a novel approach to the interaction between tall buildings and their environment. Through this approach the research proposes a new relationship between buildings and the flows around, through and inside them, where buildings could adapt to better control and manage the air flow around them, and consequently produce significant opportunities to reduce

  10. Performance enhancement of solar module by cooling: An experimental investigation

    Directory of Open Access Journals (Sweden)

    P G Nikhil, M Premalatha

    2012-01-01

    Full Text Available The study evaluates the silicone oil cooling of the solar module surface. Solar module with maximum power of 7W was employed for cooling. This paper summarizes the result of an outdoor experiment. The experiments were conducted in batch mode, with the cooling medium spread on the module surface at different thickness from 0mm to 6mm. The performance of the module, throughout the day, for different thickness of the medium is reported. The study also presents a mathematical model, predicting the variation of the maximum power when the module surface is cooled using silicone oil. The results of the equation model are compared and validated with the experimental as well as with results reported in the earlier works. The cooling contributes to appreciable improvement in the module efficiency to above 20%.

  11. Unsteady aerodynamic interaction effects on turbomachinery blade life and performance

    Science.gov (United States)

    Adamczyk, John J.

    1992-01-01

    This paper is an attempt to address the impact of a class of unsteady flows on the life and performance of turbomachinery blading. These class of flows to be investigated are those whose characteristic frequency is an integral multiple of rotor shaft speed. Analysis of data recorded downstream of a compressor and turbine rotor will reveal that this class of flows can be highly three-dimensional and may lead to the generation of secondary flows within downstream blading. By explicitly accounting for these unsteady flows in the design of turbomachinery blading for multistage applications, it may be possible to bring about gains in performance and blade life.

  12. Experimental Methods for UAV Aerodynamic and Propulsion Performance Assessment

    Directory of Open Access Journals (Sweden)

    Stefan ANTON

    2015-06-01

    Full Text Available This paper presents an experimental method for assessing the performances and the propulsion power of a UAV in several points based on telemetry. The points in which we make the estimations are chosen based on several criteria and the fallowing parameters are measured: airspeed, time-to-climb, altitude and the horizontal distance. With the estimated propulsion power and knowing the shaft motor power, the propeller efficiency is determined at several speed values. The shaft motor power was measured in the lab using the propeller as a break. Many flights, using the same UAV configuration, were performed before extracting flight data, in order to reduce the instrumental or statistic errors. This paper highlights both the methodology of processing the data and the validation of theoretical results.

  13. Aerodynamic Analysis of Cup Anemometers Performance: The Stationary Harmonic Response

    OpenAIRE

    Santiago Pindado; Javier Cubas; Ángel Sanz-Andrés

    2013-01-01

    The effect of cup anemometer shape parameters, such as the cups’ shape, their size, and their center rotation radius, was experimentally analyzed. This analysis was based on both the calibration constants of the transfer function and the most important harmonic term of the rotor’s movement, which due to the cup anemometer design is the third one. This harmonic analysis represents a new approach to study cup anemometer performances. The results clearly showed a good correlation between the ave...

  14. Aerodynamic analysis of cup anemometers performance: the stationary harmonic response.

    Science.gov (United States)

    Pindado, Santiago; Cubas, Javier; Sanz-Andrés, Angel

    2013-01-01

    The effect of cup anemometer shape parameters, such as the cups' shape, their size, and their center rotation radius, was experimentally analyzed. This analysis was based on both the calibration constants of the transfer function and the most important harmonic term of the rotor's movement, which due to the cup anemometer design is the third one. This harmonic analysis represents a new approach to study cup anemometer performances. The results clearly showed a good correlation between the average rotational speed of the anemometer's rotor and the mentioned third harmonic term of its movement.

  15. Aerodynamics for Loads and Performance of Wind Turbines and Propellers

    Energy Technology Data Exchange (ETDEWEB)

    Montgomerie, Bjoern [FOI - Swedish Defence Research Agency, Stockholm (Sweden). FFA Aeronautics

    2003-03-01

    This documentation summarizes a method for converting two dimensional wing profile data to usable three dimensional data to be applied to performance and load generation for horizontal axis wind turbines and propellers. The methods described are to be seen as preliminary in a larger context where several activities cooperate to yield reliable prediction of foremost stall controlled wind turbine loading. Complementary future activities, not included in this document, are further development of the methods presented here, computer programming, exercising the program against measured data and consequential model parameter adjustment and method modification.

  16. Aerodynamic Analysis of Cup Anemometers Performance: The Stationary Harmonic Response

    Directory of Open Access Journals (Sweden)

    Santiago Pindado

    2013-01-01

    Full Text Available The effect of cup anemometer shape parameters, such as the cups’ shape, their size, and their center rotation radius, was experimentally analyzed. This analysis was based on both the calibration constants of the transfer function and the most important harmonic term of the rotor’s movement, which due to the cup anemometer design is the third one. This harmonic analysis represents a new approach to study cup anemometer performances. The results clearly showed a good correlation between the average rotational speed of the anemometer’s rotor and the mentioned third harmonic term of its movement.

  17. Numerical investigation of geometric parameter effects on the aerodynamic performance of a Bladeless fan

    Directory of Open Access Journals (Sweden)

    Mohammad Jafari

    2016-03-01

    Full Text Available Aerodynamic performance of a Bladeless fan is numerically investigated considering the effect of five geometric parameters. Airflow through this fan was analyzed by simulating a Bladeless fan within a 2 m × 2 m × 4 m room. Analysis of the flow field inside the fan and the evaluation of its performance were obtained by solving conservations of mass and momentum equations for the aerodynamic investigations. In order to design the Bladeless fan an Eppler 473 airfoil profile was used as the cross section of the fan. Five distinct parameters, namely height of cross section of the fan, outlet angle of the flow relative to the fan axis, thickness of airflow outlet slit, hydraulic diameter, and aspect ratio for circular and quadratic cross sections were considered. Validating 3-D numerical results, experimental results of a round jet showed good agreement with those of the simulation data. The multiplier factor M is defined to show the ratio of the outlet flow rate to inlet flow rate from the fan. The obtained numerical results showed that the Discharge ratio has the maximum value for the height of 3 cm. The numerical outcomes of outlet thickness variation indicate that this parameter is one of the most influential parameters on the aerodynamic performance of a Bladeless fan. The results for the outlet thicknesses of 1, 2 and 3 mm showed that the Discharge ratio increased significantly when the outlet thickness decreased.

  18. Computational Study on the Aerodynamic Performance of Wind Turbine Airfoil Fitted with Coandă Jet

    Directory of Open Access Journals (Sweden)

    H. Djojodihardjo

    2013-01-01

    Full Text Available Various methods of flow control for enhanced aerodynamic performance have been developed and applied to enhance and control the behavior of aerodynamic components. The use of Coandă effect for the enhancement of circulation and lift has gained renewed interest, in particular with the progress of CFD. The present work addresses the influence, effectiveness, and configuration of Coandă-jet fitted aerodynamic surface for improving lift and L/D, specifically for S809 airfoil, with a view on its incorporation in the wind turbine. A simple two-dimensional CFD modeling using k-ɛ turbulence model is utilized to reveal the key elements that could exhibit the desired performance for a series of S809 airfoil configurations. Parametric study performed indicates that the use of Coandă-jet S809 airfoil can only be effective in certain range of trailing edge rounding-off radius, Coandă-jet thickness, and momentum jet size. The location of the Coandă-jet was found to be effective when it is placed close to the trailing edge. The results are compared with experimental data for benchmarking. Three-dimensional configurations are synthesized using certain acceptable assumptions. A trade-off study on the S809 Coandă configured airfoil is needed to judge the optimum configuration of Coandă-jet fitted Wind-Turbine design.

  19. An Experimental Study on the aerodynamic and aeroacoustic performances of Maple-Seed-Inspired UAV Propellers

    Science.gov (United States)

    Hu, Hui; Ning, Zhe

    2016-11-01

    Due to the auto-rotating trait of maple seeds during falling down process, flow characteristics of rotating maple seeds have been studied by many researchers in recent years. In the present study, an experimental investigation was performed to explore maple-seed-inspired UAV propellers for improved aerodynamic and aeroacoustic performances. Inspired by the auto-rotating trait of maple seeds, the shape of a maple seed is leveraged for the planform design of UAV propellers. The aerodynamic and aeroacoustic performances of the maple-seed-inspired propellers are examined in great details, in comparison with a commercially available UAV propeller purchased on the market (i.e., a baseline propeller). During the experiments, in addition to measuring the aerodynamic forces generated by the maple-seed-inspired propellers and the baseline propeller, a high-resolution Particle Image Velocimetry (PIV) system was used to quantify the unsteady flow structures in the wakes of the propellers. The aeroacoustic characteristics of the propellers are also evaluated by leveraging an anechoic chamber available at the Aerospace Engineering Department of Iowa State University. The research work is supported by National Science Foundation under Award Numbers of OSIE-1064235.

  20. Effects of Wing-Cuff on NACA 23015 Aerodynamic Performances

    Directory of Open Access Journals (Sweden)

    Meftah S.M.A

    2014-03-01

    Full Text Available The main subject of this work is the numerical study control of flow separation on a NACA 23015 airfoil by using wing cuff. This last is a leading edge modification done to the wing. The modification consists of a slight extension of the chord on the outboard section of the wings. Different numerical cases are considered for the baseline and modified airfoil NACA 23015 according at different angle of incidence. The turbulence is modeled by two equations k-epsilon model. The results of this numerical investigation showed several benefits of the wing cuff compared with a conventional airfoil and an agreement is observed between the experimental data and the present study. The most intriguing result of this research is the capability for wing cuff to perform short take-offs and landings.

  1. PERFORMANCE EVALUATION OF CEILING RADIANT COOLING SYSTEM IN COMPOSITE CLIMATE

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anuj [Malaviya National Institute of Technology (MNIT), Jaipur, India; Mathur, Jyotirmay [Malaviya National Institute of Technology (MNIT), Jaipur, India; Bhandari, Mahabir S [ORNL

    2015-01-01

    Radiant cooling systems are proving to be an energy efficient solution due to higher thermal capacity of cooling fluid especially for the buildings that require individual zone controls and where the latent loads are moderate. The Conventional air conditioners work at very low temperature i.e.5-8 c (refrigerant evaporator inlet) while the radiant cooling systems, also referred as high temperature cooling system, work at high temperatures i.e. 14-18 c. The radiant cooling systems can maintain lower MRT (Mean Radiant Temperature) as ceiling panels maintain uniform temperature gradient inside room and provide higher human comfort. The radiant cooling systems are relatively new systems and their operation and energy savings potential are not quantified for a large number of buildings and operational parameters. Moreover, there are only limited numbers of whole building simulation studies have been carried out for these systems to have a full confidence in the capability of modelling tools to simulate these systems and predict the impact of various operating parameters. Theoretically, savings achieve due to higher temperature set point of chilled water, which reduces chiller-running time. However, conventional air conditioner runs continuously to maintain requisite temperature. In this paper, experimental study for performance evaluation of radiant cooling system carried out on system installed at Malaviya National Institute of Technology Jaipur. This paper quantifies the energy savings opportunities and effective temperature by radiant cooling system at different chilled water flow rates and temperature range. The data collected/ analysed through experimental study will used for calibration and validation of system model of building prepared in building performance simulation software. This validated model used for exploring optimized combinations of key parameters for composite climate. These optimized combinations will used in formulation of radiant cooling system

  2. Aerodynamic flight performance in flap-gliding birds and bats.

    Science.gov (United States)

    Muijres, Florian T; Henningsson, Per; Stuiver, Melanie; Hedenström, Anders

    2012-08-07

    Many birds use a flight mode called undulating or flap-gliding flight, where they alternate between flapping and gliding phases, while only a few bats make use of such a flight mode. Among birds, flap-gliding is commonly used by medium to large species, where it is regarded to have a lower energetic cost than continuously flapping flight. Here, we introduce a novel model for estimating the energetic flight economy of flap-gliding animals, by determining the lift-to-drag ratio for flap-gliding based on empirical lift-to-drag ratio estimates for continuous flapping flight and for continuous gliding flight, respectively. We apply the model to flight performance data of the common swift (Apus apus) and of the lesser long-nosed bat (Leptonycteris yerbabuenae). The common swift is a typical flap-glider while-to the best of our knowledge-the lesser long-nosed bat does not use flap-gliding. The results show that, according to the model, the flap-gliding common swift saves up to 15% energy compared to a continuous flapping swift, and that this is primarily due to the exceptionally high lift-to-drag ratio in gliding flight relative to that in flapping flight for common swifts. The lesser long-nosed bat, on the other hand, seems not to be able to reduce energetic costs by flap-gliding. The difference in relative costs of flap-gliding flight between the common swift and the lesser long-nosed bat can be explained by differences in morphology, flight style and wake dynamics. The model presented here proves to be a valuable tool for estimating energetic flight economy in flap-gliding animals. The results show that flap-gliding flight that is naturally used by common swifts is indeed the most economic one of the two flight modes, while this is not the case for the non-flap-gliding lesser long-nosed bat.

  3. Modeling the Aerodynamics and Performances of a Historic Airplane: the Spanish

    Directory of Open Access Journals (Sweden)

    A. González-Betes

    2003-01-01

    Full Text Available The process of modeling the aerodynamics and performances of a historic airplane is very similar to the conceptual and preliminary design phases of a new plane, with the advantage of knowing the configuration and that the airplane was airworthy; thus it is unnecessary to outline and assess many different alternatives. However, the drag polar, the real performances, stability features, etc, are still unknown. For various reasons (in particular because of two World Wars, or the Civil War in the Spanish case most details of many historical airplanes have been lost.In the present research work, the situation is as follows. In June 1933 the "Cuatro Vientos", a Spanish-built Bréguet XIX Super TR, flew non-stop from Seville to Cuba; a distance of 7500 km (about 4100 nautical miles in around 40 hours. A few days later, in a far less complicated stage between Havana and Mexico, the airplane was lost with its occupants to a storm in the Yucatan peninsula.The modeling considered in this paper starts by addressing the aerodynamic modifications introduced in the airplane for the extremely long flight. Then, with the help of old and present day aerodynamic data and methods the drag polar is estimated. The available engine data is completed and extrapolated to obtain information on power and fuel consumption. Finally, all this data is integrated to provide a reliable and technically sound reproduction of the Seville-Cuba flight.

  4. Effect of tip geometry and tip clearance on aerodynamic performance of a linear compressor cascade

    Institute of Scientific and Technical Information of China (English)

    Zhong Jingjun; Han Shaobing; Lu Huawei; Kan Xiaoxu

    2013-01-01

    The tip leakage flow between a blade and a casing wall has a strong impact on compressor pressure rise capability,efficiency,and stability.Consequently,there is a strong motivation to look for means to minimize its impact on performance.This paper presents the potential of passive tip leakage flow control to increase the aerodynamic performance of highly loaded compressor blades.Experimental investigations on a linear compressor cascade equipped with blade winglets mounted to the blade tips have been carried out.Results for a variation of the tip clearance and the winglet geometry are presented.Current results indicate that the use of proper tip winglets in a compressor cascade can positively affect the local aerodynamic field by weakening the tip leakage vortex.Results also show that the suction-side winglets are aerodynamically superior to the pressure-side or combined winglets.The suction-side winglets are capable of reducing the exit total pressure loss associated with the tip leakage flow and the passage secondary flow to a significant degree.

  5. Numerical and experimental study on aerodynamic performance of small axial flow fan with splitter blades

    Science.gov (United States)

    Zhu, Lifu; Jin, Yingzi; Li, Yi; Jin, Yuzhen; Wang, Yanping; Zhang, Li

    2013-08-01

    To improve the aerodynamic performance of small axial flow fan, in this paper the design of a small axial flow fan with splitter blades is studied. The RNG k-ɛ turbulence model and SIMPLE algorithm were applied to the steady simulation calculation of the flow field, and its result was used as the initial field of the large eddy simulation to calculate the unsteady pressure field. The FW-H noise model was adopted to predict aerodynamic noise in the six monitoring points. Fast Fourier transform algorithm was applied to process the pressure signal. Experiment of noise testing was done to further investigate the aerodynamic noise of fans. And then the results obtained from the numerical simulation and experiment were described and analyzed. The results show that the static characteristics of small axial fan with splitter blades are similar with the prototype fan, and the static characteristics are improved within a certain range of flux. The power spectral density at the six monitoring points of small axial flow fan with splitter blades have decreased to some extent. The experimental results show sound pressure level of new fan has reduced in most frequency bands by comparing with prototype fan. The research results will provide a proof for parameter optimization and noise prediction of small axial flow fans with high performance.

  6. Phase space density as a measure of cooling performance for the international muon ionization cooling experiment

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2015-05-03

    The International Muon Ionization Cooling Experiment (MICE) is an experiment to demonstrate ionization cooling of a muon beam in a beamline that shares characteristics with one that might be used for a muon collider or neutrino factory. I describe a way to quantify cooling performance by examining the phase space density of muons, and determining how much that density increases. This contrasts with the more common methods that rely on the covariance matrix and compute emittances from that. I discuss why a direct measure of phase space density might be preferable to a covariance matrix method. I apply this technique to an early proposal for the MICE final step beamline. I discuss how matching impacts the measured performance.

  7. Hydronic radiant cooling: Overview and preliminary performance assessment

    Energy Technology Data Exchange (ETDEWEB)

    Feustel, H.E.

    1993-05-01

    A significant amount of electrical energy used to cool non-residential buildings is drawn by the fans used to transport the cool air through the thermal distribution system. Hydronic systems reduce the amount of air transported through the building by separating ventilation and thermal conditioning. Due to the physical properties of water, hydronic distribution systems can transport a given amount of thermal energy using less than 5% of the otherwise necessary fan energy. This savings alone significantly reduces the energy consumption and especially the peak power requirement This survey clearly shows advantages for radiant cooling in combination with hydronic thermal distribution systems in comparison with the All-Air Systems commonly used in California. The report describes a literature survey on the system`s development, thermal comfort issues, and cooling performance. The cooling power potential and the cooling power requirement are investigated for several California climates. Peak-power requirement is compared for hydronic radiant cooling and conventional All-Air-Systems.

  8. Hydronic radiant cooling: Overview and preliminary performance assessment

    Energy Technology Data Exchange (ETDEWEB)

    Feustel, H.E.

    1993-05-01

    A significant amount of electrical energy used to cool non-residential buildings is drawn by the fans used to transport the cool air through the thermal distribution system. Hydronic systems reduce the amount of air transported through the building by separating ventilation and thermal conditioning. Due to the physical properties of water, hydronic distribution systems can transport a given amount of thermal energy using less than 5% of the otherwise necessary fan energy. This savings alone significantly reduces the energy consumption and especially the peak power requirement This survey clearly shows advantages for radiant cooling in combination with hydronic thermal distribution systems in comparison with the All-Air Systems commonly used in California. The report describes a literature survey on the system's development, thermal comfort issues, and cooling performance. The cooling power potential and the cooling power requirement are investigated for several California climates. Peak-power requirement is compared for hydronic radiant cooling and conventional All-Air-Systems.

  9. Inlet Flux Influence to Aerodynamic Performance of Steam Turbine Vane Cascade

    Directory of Open Access Journals (Sweden)

    Feng Zi-Ming

    2014-12-01

    Full Text Available In order to improve the aerodynamic performance and the performance of off-design working condition, it is necessary to research the inlet flow rate influence to overall performance of steam turbine. This study uses CFD technology to numerical simulation the flow field of nozzle cascades passage at 80, 100, 120% flow rate, respectively. The simulation results indicates that the various flow loss of nozzle have a little change at 100% design working condition, have decreased at 80% design working condition and have increased at 120% design working condition.

  10. The role of free stream turbulence and blade surface conditions on the aerodynamic performance of wind turbine blades

    Science.gov (United States)

    Maldonado, Victor Hugo

    Wind turbines operate within the atmospheric boundary layer (ABL) which gives rise to turbulence among other flow phenomena. There are several factors that contribute to turbulent flow: The operation of wind turbines in two layers of the atmosphere, the surface layer and the mixed layer. These layers often have unstable wind conditions due to the daily heating and cooling of the atmosphere which creates turbulent thermals. In addition, wind turbines often operate in the wake of upstream turbines such as in wind farms; where turbulence generated by the rotor can be compounded if the turbines are not sited properly. Although turbulent flow conditions are known to affect performance, i.e. power output and lifespan of the turbine, the flow mechanisms by which atmospheric turbulence and other external conditions (such as blade debris contamination) adversely impact wind turbines are not known in enough detail to address these issues. The main objectives of the current investigation are thus two-fold: (i) to understand the interaction of the turbulent integral length scales and surface roughness on the blade and its effect on aerodynamic performance, and (ii) to develop and apply flow control (both passive and active) techniques to alleviate some of the adverse fluid dynamics phenomena caused by the atmosphere (i.e. blade contamination) and restore some of the aerodynamic performance loss. In order to satisfy the objectives of the investigation, a 2-D blade model based on the S809 airfoil for horizontal axis wind turbine (HAWT) applications was manufactured and tested at the Johns Hopkins University Corrsin Stanley Wind Tunnel facility. Additional levels of free stream turbulence with an intensity of 6.14% and integral length scale of about 0.321 m was introduced into the flow via an active grid. The free stream velocity was 10 m/s resulting in a Reynolds number based on blade chord of Rec ≃ 2.08x105. Debris contamination on the blade was modeled as surface roughness

  11. Cryogenic performance of a cryocooler-cooled superconducting undulator

    Energy Technology Data Exchange (ETDEWEB)

    Fuerst, J. D.; Doose, C.; Hasse, Q.; Ivanyushenkov, Y.; Kasa, M.; Shiroyanagi, Y. [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2014-01-29

    A cryocooler-cooled superconducting undulator has been installed and operated with beam at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The device consists of a dual-core 42-pole magnet structure that is cooled to 4.2 K with a system of four cryocoolers operating in a zero-boil-off configuration. This effort represents the culmination of a development program to establish concept feasibility and evaluate cryostat design and cryocooler-based refrigeration. Cryostat performance is described including cool-down/warm-up, steady-state operation, cooling margin, and the impact of beam during operation in the APS storage ring. Plans for future devices with longer magnets, which will incorporate lessons learned from the development program, are also discussed.

  12. Indigenous development and performance evaluation of BARC aerodynamic size separator (BASS)

    CERN Document Server

    Singh, S; Khan, A; Mayya, Y S; Narayanan, K P; Purwar, R C; Sapra, B K; Sunny, F

    2002-01-01

    Commercially available cascade impactors, commonly used for aerodynamic size separation of aerosol particles, are based on the principle of inertial impaction. As of now, these instruments are imported at a cost of several lakhs of rupees; hence an effort has been made to develop an aerodynamic particle sizer indigenously in BARC. This unit, referred to as BARC Aerodynamic Size Separator (BASS), separates aerosols into seven size classes ranging from 0.53 mu m to 10 mu m and operates at a flow rate of 45 Ipm. Intercomparison studies between the standard Andersen Mark-II (Grasbey Andersen Inc.) impactor and BASS using nebulizer generated aerosols have consistently shown excellent performance by BASS in all respects. In particular, BASS yielded the parameters of polydisperse aerosols quite accurately. Experiments to evaluate the individual stage cut-off diameters show that these are within 8% of their designed value for all stages except the higher two stages which indicate about 30% lower values than the desig...

  13. Effect of Vane Opening on Aerodynamic Performance of the Ram-rotor Test System

    Institute of Scientific and Technical Information of China (English)

    HAN Ji-ang; GUAN Jian; ZHONG Jingjun; YUAN Chenguang

    2016-01-01

    In order to research the influence of adjustable vane on the aerodynamic performance of the ram-rotor test system,FLUENT software has been adopted to simulate the flow passage of the ram-rotor test system numerically.The vane opening is controlled by changing the stagger angle of the vane blades.Results show that flow uniformity of vane outlet is influenced by the vane openings,which has an impact on the aerodynamic loss to some extent.Total pressure ratio,adiabatic efficiency and mass flow rate can be regulated by different openings of the vane.Compared with-8° vane opening,top efficiency of the ram-rotor increases by about 13.8% at +6° opening.And total pressure ratio drops by 5.87%.The rising opening increases the relative Mach number at inlet of the ram-rotor and weakens the intensity of the tip clearance leakage,which comes to a decreasing aerodynamic loss.

  14. Performance Evaluation of Photovoltaic Solar Panel Using Thermoelectric Cooling

    Directory of Open Access Journals (Sweden)

    Mr. Dinesh S. Borkar , Dr.Sunil.V.Prayagi, Ms. Jayashree Gotmare

    2014-01-01

    Full Text Available As a great potential renewable energy source, solar energy is becoming one of the most important energies in the future. Performance of PV panel decreases with increase in temperature of the PV panel. Hence, output power of PV module drops with rise in temperature, if heat is not removed. The cooling of PV modules would enhance the performance of PV panel. In order to cool this thermoelectric system is used. Hybridisation of PV module with thermoelectric modules used to increase the overall efficiency of the solar energy conversion system by keeping temperature constant within the limits. Model of hybrid combination of PV–Thermoelectric has been developed and study of thermoelectric has done to illustrate its usefulness in hybrid model of PV and thermoelectric modules. This paper shows the performance of PV panel through augmentation of thermoelectric cooling system to increase overall electric conversion efficiency of PV array.

  15. Preliminary Assessment of a Debris Bed Cooling Performance for Demonstration Sodium-cooled Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Chung Ho; Park, Chang Gyu; Song, Hoon; Kim, Young Gyun; Jeong, Hae Yong; Chang, Jin Wook [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    In the case of the sodium-cooled fast reactor such as KALIMER-600, Hypothetical Core Disruptive Accident (HCDA) attributed from mass nuclear fuel melting is unlikely to occur due to defense in depth concepts to meet requirements of redundancy and diversity. Multiple faults such as loss of flow, loss of heat sink, or transient overpower without scram are to lead rising the power level until cladding failure as reactivity increasing. The fact that metallic fuel melts at a lower temperature than the cladding allows significant in-pin- fuel motion to occur prior to cladding failure. Also, the combination of Doppler and axial expansion feedback and negative feedback associated with the in-pin fuel relocation prevents the reactivity from reaching prompt critical. Finally, the resulting reactivity and power reductions help prevent fuel temperatures from rising more than the fuel melting temperature. It is more difficult to occur HCDA in a metallic fueled core because reactor power and heat removal capability is maintained in balance by inherent safety characteristics However, for the future design of sodium-cooled fast reactor, the evaluation of the safety performance and the determination of containment requirements may be worth considering due to the triple-fault accident sequences of extremely low probability of occurrence that leads to core melting. For any postulated accident sequence which leads to core melting, in-vessel retention of the core debris will be required as a design requirement for the future design of sodium cooled fast reactor. Also, proof of the capacity of the debris bed cooling is an essential condition to solve the problem of in-vessel retention of the core debris. Accordingly, evaluation of a packed debris bed cooling performance with single phase flow for demonstration sodium-cooled fast reactor was carried out for proof of the in-vessel retention of the core debris

  16. Cooling Performance of Natural Circulation for a Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, Suki; Chun, J. H.; Yum, S. B. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    This paper deals with the core cooling performance by natural circulation during normal operation and a flow channel blockage event in an open tank-in-pool type research reactor. The cooling performance is predicted by using the RELAP5/ MOD3.3 code. The core decay heat is usually removed by natural circulation to the reactor pool water in open tank-in-pool type research reactors with the thermal power less than several megawatts. Therefore, these reactors have generally no active core cooling system against a loss of normal forced flow. In reactors with the thermal power less than around one megawatt, the reactor core can be cooled down by natural circulation even during normal full power operation. The cooling performance of natural circulation in an open tank-in-pool type research reactor has been investigated during the normal natural circulation and a flow channel blockage event. It is found that the maximum powers without void generation at the hot channel are around 1.16 MW and 820 kW, respectively, for the normal natural circulation and the flow channel blockage event.

  17. Performance test of solar-assisted ejector cooling system

    KAUST Repository

    Huang, Bin-Juine

    2014-03-01

    A solar-assisted ejector cooling/heating system (SACH-2k) is built and test result is reported. The solar-driven ejector cooling system (ECS) is connected in series with an inverter-type air conditioner (IAC). Several advanced technologies are developed in SACH-k2, including generator liquid level control in ECS, the ECS evaporator temperature control, and optimal control of fan power in cooling tower of ECS. From the field test results, the generator liquid level control performs quite well and keeps stable performance of ejector. The ECS evaporator temperature control also performs satisfactorily to keep ejector performance normally under low or fluctuating solar radiation. The fan power control system cooling tower performs stably and reduces the power consumption dramatically without affecting the ECS performance. The test results show that the overall system COPo including power consumptions of peripheral increases from 2.94-3.3 (IAC alone) to 4.06-4.5 (SACH-k2), about 33-43%. The highest COPo is 4.5. © 2013 Elsevier Ltd and IIR. All rights reserved.

  18. Desiccant aging and its effect on desiccant cooling system performance

    Energy Technology Data Exchange (ETDEWEB)

    Belding, W.A. [Innovative Research Enterprises, Danville, CA (United States); Delmas, M.P.F.; Holeman, W.D. [LaRoche Industries Inc., Baton Rouge, LA (United States)

    1996-05-01

    Desiccants used for the purpose of space conditioning or enthalpy transfer can be subjected to hundreds of thousands of adsorption/regeneration cycles over their useful life. Studying the loss of a desiccant`s equilibrium water adsorption capacity after exposure to thermal cycling is a common method for quantifying desiccant aging. Since isotherm shape and desiccant capacity can be related to overall cooling-system performance, system cooling capacity and coefficients of performance over time can be predicted. Adsorption isotherms for several different desiccants have been determined after subjecting the materials to varying numbers of thermal cycles in a specially designed test unit capable of adsorption/desorption cycling every 10 min. Aging curves for a new Type 1M desiccant developed specifically for desiccant cooling applications by LaRoche Industries Inc. are compared to other commonly used desiccants. (author)

  19. Numerical Investigations on the Aerodynamic Performance of Wind Turbine:Downwind Versus Upwind Configuration

    Institute of Scientific and Technical Information of China (English)

    Hu Zhou; Decheng Wan

    2015-01-01

    Although the upwind configuration is more popular in the field of wind energy, the downwind one is a promising type for the offshore wind energy due to its special advantages. Different configurations have different aerodynamic performance and it is important to predict the performance of both downwind and upwind configurations accurately for designing and developing more reliable wind turbines. In this paper, a numerical investigation on the aerodynamic performance of National Renewable Energy Laboratory (NREL) phase VI wind turbine in downwind and upwind configurations is presented. The open source toolbox OpenFOAM coupled with arbitrary mesh interface (AMI) method is applied to tackle rotating problems of wind turbines. Two 3D numerical models of NREL phase VI wind turbine with downwind and upwind configurations under four typical working conditions of incoming wind velocities are set up for the study of different unsteady characteristics of the downwind and upwind configurations, respectively. Numerical results of wake vortex structure, time histories of thrust, pressure distribution on the blade and limiting streamlines which can be used to identify points of separation in a 3D flow are presented. It can be concluded that thrust reduction due to blade-tower interaction is small for upwind wind turbines but relatively large for downwind wind turbines and attention should be paid to the vibration at a certain frequency induced by the cyclic reduction for both configurations. The results and conclusions are helpful to analyze the different aerodynamic performance of wind turbines between downwind and upwind configurations, providing useful references for practical design of wind turbine.

  20. Numerical investigations on the aerodynamic performance of wind turbine: Downwind versus upwind configuration

    Science.gov (United States)

    Zhou, Hu; Wan, Decheng

    2015-03-01

    Although the upwind configuration is more popular in the field of wind energy, the downwind one is a promising type for the offshore wind energy due to its special advantages. Different configurations have different aerodynamic performance and it is important to predict the performance of both downwind and upwind configurations accurately for designing and developing more reliable wind turbines. In this paper, a numerical investigation on the aerodynamic performance of National Renewable Energy Laboratory (NREL) phase VI wind turbine in downwind and upwind configurations is presented. The open source toolbox OpenFOAM coupled with arbitrary mesh interface (AMI) method is applied to tackle rotating problems of wind turbines. Two 3D numerical models of NREL phase VI wind turbine with downwind and upwind configurations under four typical working conditions of incoming wind velocities are set up for the study of different unsteady characteristics of the downwind and upwind configurations, respectively. Numerical results of wake vortex structure, time histories of thrust, pressure distribution on the blade and limiting streamlines which can be used to identify points of separation in a 3D flow are presented. It can be concluded that thrust reduction due to blade-tower interaction is small for upwind wind turbines but relatively large for downwind wind turbines and attention should be paid to the vibration at a certain frequency induced by the cyclic reduction for both configurations. The results and conclusions are helpful to analyze the different aerodynamic performance of wind turbines between downwind and upwind configurations, providing useful references for practical design of wind turbine.

  1. Design of low noise airfoil with high aerodynamic performance for use on small wind turbines

    Institute of Scientific and Technical Information of China (English)

    Taehyung; KIM; Seungmin; LEE; Hogeon; KIM; Soogab; LEE

    2010-01-01

    Wind power is one of the most reliable renewable energy sources and internationally installed capacity is increasing radically every year.Although wind power has been favored by the public in general,the problem with the impact of wind turbine noise on people living in the vicinity of the turbines has been increased.Low noise wind turbine design is becoming more and more important as noise is spreading more adverse effect of wind turbine to public.This paper demonstrates the design of 10 kW class wind turbines,each of three blades,a rotor diameter 6.4 m,a rated rotating speed 200 r/min and a rated wind speed 10 m/s.The optimized airfoil is dedicated for the 75% spanwise position because the dominant source of a wind turbine blade is trailing edge noise from the outer 25% of the blade.Numerical computations are performed for incompressible flow and for Mach number at 0.145 and for Reynolds numbers at 1.02×106 with a lift performance,which is resistant to surface contamination and turbulence intensity.The objectives in the design process are to reduce noise emission,while sustaining high aerodynamic efficiency.Dominant broadband noise sources are predicted by semi-empirical formulas composed of the groundwork by Brooks et al.and Lowson associated with typical wind turbine operation conditions.During the airfoil redesign process,the aerodynamic performance is analyzed to reduce the wind turbine power loss.The results obtained from the design process show that the design method is capable of designing airfoils with reduced noise using a commercial 10 kW class wind turbine blade airfoil as a basis.Therefore,the new optimized airfoil showing 2.9 dB reductions of total sound pressure level(SPL) and higher aerodynamic performance are achieved.

  2. Laboratory evaluation of fan/filter units' aerodynamic and energy performance

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tengfang; Jeng, Ming-Shan

    2004-07-27

    The paper discusses the benefits of having a consistent testing method to characterize aerodynamic and energy performance of FFUs. It presents evaluation methods of laboratory-measured performance of ten relatively new, 1220 mm x 610 mm (or 4 ft x 2 ft) fan-filter units (FFUs), and includes results of a set of relevant metrics such as energy performance indices (EPI) based upon the sample FFUs tested. This paper concludes that there are variations in FFUs' performance, and that using a consistent testing and evaluation method can generate compatible and comparable FFU performance information. The paper also suggests that benefits and opportunities exist for our method of testing FFU energy performance to be integrated in future recommended practices.

  3. Development of Pneumatic Aerodynamic Devices to Improve the Performance, Economics, and Safety of Heavy Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Robert J. Englar

    2000-06-19

    Under contract to the DOE Office of Heavy Vehicle Technologies, the Georgia Tech Research Institute (GTRI) is developing and evaluating pneumatic (blown) aerodynamic devices to improve the performance, economics, stability and safety of operation of Heavy Vehicles. The objective of this program is to apply the pneumatic aerodynamic aircraft technology previously developed and flight-tested by GTRI personnel to the design of an efficient blown tractor-trailer configuration. Recent experimental results obtained by GTRI using blowing have shown drag reductions of 35% on a streamlined automobile wind-tunnel model. Also measured were lift or down-load increases of 100-150% and the ability to control aerodynamic moments about all 3 axes without any moving control surfaces. Similar drag reductions yielded by blowing on bluff afterbody trailers in current US trucking fleet operations are anticipated to reduce yearly fuel consumption by more than 1.2 billion gallons, while even further reduction is possible using pneumatic lift to reduce tire rolling resistance. Conversely, increased drag and down force generated instantaneously by blowing can greatly increase braking characteristics and control in wet/icy weather due to effective ''weight'' increases on the tires. Safety is also enhanced by controlling side loads and moments caused on these Heavy Vehicles by winds, gusts and other vehicles passing. This may also help to eliminate the jack-knifing problem if caused by extreme wind side loads on the trailer. Lastly, reduction of the turbulent wake behind the trailer can reduce splash and spray patterns and rough air being experienced by following vehicles. To be presented by GTRI in this paper will be results developed during the early portion of this effort, including a preliminary systems study, CFD prediction of the blown flowfields, and design of the baseline conventional tractor-trailer model and the pneumatic wind-tunnel model.

  4. Effects of Leaders Position and Shape on Aerodynamic Performances of V Flight Formation

    CERN Document Server

    Thien, H P; Muhammad, H

    2008-01-01

    The influences of the leader in a group of V flight formation are dealt with. The investigation is focused on the effect of its position and shape on aerodynamics performances of a given V flight formation. Vortices generated the wing tip of the leader moves downstream forming a pair of opposite rotating line vortices. These vortices are generally undesirable because they create a downwash that increases the induced drag on leaders wing. However, this downwash is also accompanied by an upwash that can beneficial to the followers wing flying behind the leaders one, namely a favorable lift for the followers wing. How much contributions of the leaders wing to the followers wing in the V formation flight is determined by the strength of tip vortices generated by the leaders wing which is influenced by its position and shape including incidence angle, dihedral angle, aspect ratio and taper ratio. The prediction of aerodynamic performances of the V flight formation including lift, drag and moment coefficients is nu...

  5. Improvement in Capsule Abort Performance Using Supersonic Aerodynamic Interaction by Fences

    Science.gov (United States)

    Koyama, Hiroto; Wang, Yunpeng; Ozawa, Hiroshi; Doi, Katsunori; Nakamura, Yoshiaki

    The space transportation system will need advanced abort systems to secure crew against serious accidents. Here this study deals with the capsule-type space transportation systems with a Launch Abort System (LAS). This system is composed of a conic capsule as a Launch Abort Vehicle (LAV) and a cylindrical rocket as a Service Module (SM), and the capsule is moved away from the rocket by supersonic aerodynamic interactions in an emergency. We propose a method to improve the performance of the LAV by installing fences at the edges of surfaces on the rocket and capsule sides. Their effects were investigated by experimental measurements and numerical simulations. Experimental results show that the fences on the rocket and capsule surfaces increase the aerodynamic thrust force on the capsule by 70% in a certain clearance between the capsule and rocket. Computational results show the detailed flow fields where the centripetal flow near the surface on the rocket side is induced by the fence on the rocket side and the centrifugal flow near the surface on the capsule side is blocked by the fence on the capsule side. These results can confirm favorable effects of the fences on the performance of the LAS.

  6. Numerical Analysis of Wind Turbine Airfoil Aerodynamic Performance with Leading Edge Bump

    Directory of Open Access Journals (Sweden)

    Majid Asli

    2015-01-01

    Full Text Available Aerodynamic performance improvement of wind turbine blade is the key process to improve wind turbine performance in electricity generated and energy conversion in renewable energy sources concept. The flow behavior on wind turbine blades profile and the relevant phenomena like stall can be improved by some modifications. In the present paper, Humpback Whales flippers leading edge protuberances model as a novel passive stall control method was investigated on S809 as a thick airfoil. The airfoil was numerically analyzed by CFD method in Reynolds number of 106 and aerodynamic coefficients in static angle of attacks were validated with the experimental data reported by Somers in NREL. Therefore, computational results for modified airfoil with sinusoidal wavy leading edge were presented. The results revealed that, at low angles of attacks before the stall region, lift coefficient decreases slightly rather than baseline model. However, the modified airfoil has a smooth stall trend while baseline airfoil lift coefficient decreases sharply due to the separation which occurred on suction side. According to the flow physics over the airfoils, leading edge bumps act as vortex generator so vortices containing high level of momentum make the flow remain attached to the surface of the airfoil at high angle of attack and prevent it from having a deep stall.

  7. Aerodynamic Performance and Noise Characteristics of a Centrifugal Compressor with Modified Vaned Diffusers

    Institute of Scientific and Technical Information of China (English)

    Yutaka OHTA; Yasuhiko OKUTSU; Takashi GOTO; Eisuke OUTA

    2006-01-01

    Improvement of aerodynamic performance and reduction of interaction tone noise of a centrifugal compressor with vaned diffusers are discussed by experiments and visualization techniques using a colored oil-film method.The focus of the research is concentrated on the leading edge shape of diffuser vanes that are deeply related to the generation mechanism of the interaction tone noise.The compressor-radiated noise can be reduced by more than ten decibels by using modified diffuser vanes which have 3-D tapered shapes on both pressure and suction surfaces of the leading edge.Furthermore,by adopting the proposed modified diffuser vanes,the secondary flow which is considered to be an obstruction of diffuser pressure recovery can be suppressed,and also the pressure decrease observed in the throat part of the diffuser flow passage is reducible.Thus,the proposed diffuser vanes show a favorable result for both noise and the aerodynamic performance of the centrifugal compressor,and offer a few basic guidelines for the diffuser vane design.

  8. Performance of Upgraded Cooling System for Lhd Helical Coils

    Science.gov (United States)

    Hamaguchi, S.; Imagawa, S.; Obana, T.; Yanagi, N.; Moriuchi, S.; Sekiguchi, H.; Oba, K.; Mito, T.; Motojima, O.; Okamura, T.; Semba, T.; Yoshinaga, S.; Wakisaka, H.

    2008-03-01

    Helical coils of the Large Helical Device (LHD) are large scale superconducting magnets for heliotron plasma experiments. The helical coils had been cooled by saturated helium at 4.4 K, 120 kPa until 2005. An upgrade of the cooling system was carried out in 2006 in order to improve the cryogenic stability of the helical coils and then it has been possible to supply the coils with subcooled helium at 3.2 K, 120 kPa. A designed mass flow of the supplied subcooled helium is 50 g/s. The subcooled helium is generated at a heat exchanger in a saturated helium bath. A series of two centrifugal cold compressors with gas foil bearing is utilized to lower the helium pressure in the bath. The supplied helium temperature is regulated by rotational speed of the cold compressors and power of a heater in the bath. The mass flow of the supplied helium is also controlled manually by a supply valve and its surplus is evaporated by ten heaters at the outlet above the coils. In the present study, the performance of the cooling system has been investigated and a stable operating method has also developed. As the result, it was confirmed that the performance of the upgraded cooling system satisfies the requirements.

  9. Aerodynamic performance of NACA four-digit profiles in small-scale wind turbines for small farms

    Directory of Open Access Journals (Sweden)

    Paulo Alexandre Costa Rocha

    2015-06-01

    Full Text Available In Brazil, there are many places that do not have access to electric energy, mainly in rural areas with small farms. This situation has accentuated the importance of renewable energy sources, such as wind energy. This work consisted of the design, construction and field testing of two small three-bladed wind turbines with two different aerodynamic profiles. The aim of the study was to compare the profile influence on the turbine aerodynamic performance. Using the blade element momentum (BEM theory, two wind turbines were designed and built with different cross-section aerodynamic profiles (NACA 0012 (symmetric and 4412 (chambered. Following statistical analysis, the results of the field tests demonstrated that the performances of the turbines are similar when the rotational speed is near the designed value (?=5. However, when the rotational speed is under or above the designed value, the NACA 4412 profile yields superior performance

  10. Aerodynamic performance of aerofoils obtained from a geometric offset applied to a given initial aerofoil

    Science.gov (United States)

    Sousa, Diogo; Gamboa, Pedro; Melo, David

    2016-12-01

    Many studies concerning morphing aircraft concepts in which enhanced performance and increased energy efficiency are two of the main goals have been recently conducted. Some of those concepts deal with wing span changes. In line with those, in a variable-span wing of the telescopic type, the cross-sections of the sliding panels, whether be two, three or more, must be made geometrically compatible among them. This requirement serves two purposes: to minimize the aerofoils' geometric discontinuity which negatively affects wing drag and lift; and to provide a simple structural support between any two sliding panels. This paper describes the methodology employed to develop geometrically compatible aerofoils obtained from a constant geometric offset applied to a given initial aerofoil. This methodology is used to create inward offset aerofoils and outward offset aerofoils. The geometric and aerodynamic characteristics of the resulting offset aerofoils are compared with those of the original aerofoils. From the analysis of six different original aerofoils, strong trends in the geometric changes and in the aerodynamic characteristics of the resulting inward and outward offset aerofoils are observed. Ultimately, this study can help a telescopic wing designer decide whether an inward or an outward offset aerofoil is more appropriate for the specific design at hand.

  11. Experimental study of ice accretion effects on aerodynamic performance of an NACA 23012 airfoil

    Institute of Scientific and Technical Information of China (English)

    Masoud Mirzaei; Mohammad-Mahdi Nazemi; Mojtaba Fouladi; Alireza Doostmahmoudi

    2016-01-01

    In this paper, the effects of icing on an NACA 23012 airfoil have been studied. Exper-iments were applied on the clean airfoil, runback ice, horn ice, and spanwise ridge ice at a Reynolds number of 0.6 ? 106 over angles of attack from ? 8? to 20?, and then results are compared. Gener-ally, it is found that ice accretion on the airfoil can contribute to formation of a flow separation bubble on the upper surface downstream from the leading edge. In addition, it is made clear that spanwise ridge ice provides the greatest negative effect on the aerodynamic performance of the airfoil. In this case, the stall angle drops about 10? and the maximum lift coefficient reduces about 50%which is hazardous for an airplane. While horn ice leads to a stall angle drop of about 4? and a maximum lift coefficient reduction to 21%, runback ice has the least effect on the flow pattern around the airfoil and the aerodynamic coefficients so as the stall angle decreases 2? and the maximum lift reduces about 8%.

  12. Experimental study of ice accretion effects on aerodynamic performance of an NACA 23012 airfoil

    Directory of Open Access Journals (Sweden)

    Sohrab Gholamhosein Pouryoussefi

    2016-06-01

    Full Text Available In this paper, the effects of icing on an NACA 23012 airfoil have been studied. Experiments were applied on the clean airfoil, runback ice, horn ice, and spanwise ridge ice at a Reynolds number of 0.6 × 106 over angles of attack from −8° to 20°, and then results are compared. Generally, it is found that ice accretion on the airfoil can contribute to formation of a flow separation bubble on the upper surface downstream from the leading edge. In addition, it is made clear that spanwise ridge ice provides the greatest negative effect on the aerodynamic performance of the airfoil. In this case, the stall angle drops about 10° and the maximum lift coefficient reduces about 50% which is hazardous for an airplane. While horn ice leads to a stall angle drop of about 4° and a maximum lift coefficient reduction to 21%, runback ice has the least effect on the flow pattern around the airfoil and the aerodynamic coefficients so as the stall angle decreases 2° and the maximum lift reduces about 8%.

  13. Performance characteristics in hydrodynamic water cooled thrust bearings

    Directory of Open Access Journals (Sweden)

    Farooq Ahmad Najar

    2016-09-01

    Full Text Available This paper deals with the study of the influence on performance characteristics of a thrust bearing with the introduction of cooling circuit and flow velocity of coolant within the designed thrust bearings is described. New method of cooling circuit configuration is taken into consideration and water has been chosen as a coolant here in the present work. Flow velocity of coolant, ranging from 0.5m/s to 2.0m/s is proposed. The Finite difference based numerical model has been developed in order to notice the effect on the heat transfer on a large hydrodynamic lubrication thrust bearing in-terms of its performance characteristics. In the present work, the solution of Reynolds equation, an energy equation with viscosity variation and Fourier heat conduction equations, applied with appropriate boundary conditions. From the present investigation, it is observed significant amount of heat content is removed from the bearing with the increase of flow velocity of coolant in an embedded cooling duct within the pad. An important parameter among performance characteristics has prevailed a significant increase in hydrodynamic pressure generation which in turn subsequently increases the load carrying capacity which has been never ever documented in the background literature.

  14. Investigation of the Effects of Airfoil-probes on the Aerodynamic Performance of an Axial Compressor

    Institute of Scientific and Technical Information of China (English)

    HE Xiang; MA Hongwei; REN Minglin; XIANG Honghui

    2012-01-01

    In order to investigate the effects of the airfoil-probes on the aerodynamic performance of an axial compressor,a numerical simulation of 3D flow field is performed in a 1.5-stage axial compressor with airfoil-probes installed at the stator leading-edge (LE).The airfoil-probes have a negative influence on the compressor aerodynamic performance at all operating points.A streamwise vortex is induced by the airfoil-probe along both sides of the blade.At the mid-operating point,the vortex is notable along the pressure side and is relatively small along the suction side (SS).At the near-stall point,the vortex is slightly suppressed in the pressure surface (PS),but becomes remarkable in the suction side.A small local-separation is induced by the interactions between the vortex and the end-wall boundary layer in the corner region near the hub.That the positive pitch angle of the airfoil-probe at 6.5% span is about 15° plays an important role in the vortex evolution near the hub,which causes the fact that the airfoil-probe near the hub has the largest effects among the four airfoil-probes.In order to get a further understanding of the vortex evolution in the stator in the numerical simulation,a flow visualization experiment in a water tunnel is performed.The flow visualization results give a deep insight into the evolution of the vortex induced by the airfoil-probe.

  15. Experimental evaluation of cooling efficiency of the high performance cooling device

    Science.gov (United States)

    Nemec, Patrik; Malcho, Milan

    2016-06-01

    This work deal with experimental evaluation of cooling efficiency of cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description of cooling device, working principle of cooling device, construction of cooling device. Experimental part describe the measuring method of device cooling efficiency evaluation. The work results are presented in graphic visualization of temperature dependence of the contact area surface between cooling device evaporator and electronic components on the loaded heat of electronic components in range from 250 to 740 W and temperature dependence of the loop thermosiphon condenser surface on the loaded heat of electronic components in range from 250 to 740 W.

  16. Effects of Shrouded Stator Cavity Flows on Multistage Axial Compressor Aerodynamic Performance

    Science.gov (United States)

    Wellborn, Steven R.; Okiishi, Theodore H.

    1996-01-01

    Experiments were performed on a low-speed multistage axial-flow compressor to assess the effects of shrouded stator cavity flows on aerodynamic performance. Five configurations, which involved changes in seal-tooth leakage rates and/or elimination of the shrouded stator cavities, were tested. Data collected enabled differences in overall individual stage and the third stage blade element performance parameters to be compared. The results show conclusively that seal-tooth leakage ran have a large impact on compressor aerodynamic performance while the presence of the shrouded stator cavities alone seemed to have little influence. Overall performance data revealed that for every 1% increase in the seal-tooth clearance to blade-height ratio the pressure rise dropped up to 3% while efficiency was reduced by 1 to 1.5 points. These observed efficiency penalty slopes are comparable to those commonly reported for rotor and cantilevered stator tip clearance variations. Therefore, it appears that in order to correctly predict overall performance it is equally important to account for the effects of seal-tooth leakage as it is to include the influence of tip clearance flows. Third stage blade element performance data suggested that the performance degradation observed when leakage was increased was brought about in two distinct ways. First, increasing seal-tooth leakage directly spoiled the near hub performance of the stator row in which leakage occurred. Second, the altered stator exit now conditions caused by increased leakage impaired the performance of the next downstream stage by decreasing the work input of the downstream rotor and increasing total pressure loss of the downstream stator. These trends caused downstream stages to progressively perform worse. Other measurements were acquired to determine spatial and temporal flow field variations within the up-and-downstream shrouded stator cavities. Flow within the cavities involved low momentum fluid traveling primarily

  17. Turbine Blade Cooling System Optimization

    OpenAIRE

    GIRARDEAU, Julian; PAILHES, Jérôme; SEBASTIAN, Patrick; PARDO, Frédéric; Nadeau, Jean-Pierre

    2013-01-01

    The authors wish to thank turbine designers from TURBOMECA SAFRAN Group.; International audience; Designing high performance cooling systems suitable for preserving the service lifetime of nozzle guide vanes of turboshaft engines leads to significant aerodynamic losses. These losses jeopardize the performance of the whole engine. In the same time, a low efficiency cooling system may affect the costs of maintenance repair and overhaul of the engine as component life decreases. Consequently, de...

  18. High performance infrared fast cooled detectors for missile applications

    Science.gov (United States)

    Reibel, Yann; Espuno, Laurent; Taalat, Rachid; Sultan, Ahmad; Cassaigne, Pierre; Matallah, Noura

    2016-05-01

    SOFRADIR was selected in the late 90's for the production of 320×256 MW detectors for major European missile programs. This experience has established our company as a key player in the field of missile programs. SOFRADIR has since developed a vast portfolio of lightweight, compact and high performance JT-based solutions for missiles. ALTAN is a 384x288 Mid Wave infrared detector with 15μm pixel pitch, and is offered in a miniature ultra-fast Joule- Thomson cooled Dewar. Since Sofradir offers both Indium Antimonide (InSb) and Mercury Cadmium Telluride technologies (MCT), we are able to deliver the detectors best suited to customers' needs. In this paper we are discussing different figures of merit for very compact and innovative JT-cooled detectors and are highlighting the challenges for infrared detection technologies.

  19. Aerodynamic performance of two fifteen-percent-scale wind-tunnel drive fan designs

    Science.gov (United States)

    Signor, D. B.; Borst, H. V.

    1986-01-01

    An experimental and analytical investigation of two fan blade designs was conducted. The fan blades tested were 15 percent scale models of the blades used in the National Full Scale Aerodynamic Complex fan drive at NASA Ames Research Center. The fan blades were composed of NACA-65 and modified NACA-65-series airfoil design sections. The blades with modified 65-series sections incorporated increased thickness on the upper surface, between the leading edge and the one-half chord position. Twist and taper were the same for both blade designs. The fan blades with modified 65-series sections were found to have an increase in stall margin when they were compared with the unmodified blades. The experimental performance data agreed favorably with theoretical calculations.

  20. Numerical study of improving aerodynamic performance of low solidity LPT cascade through increasing trailing edge thickness

    Science.gov (United States)

    Li, Chao; Yan, Peigang; Wang, Xiangfeng; Han, Wanjin; Wang, Qingchao

    2016-08-01

    This paper presents a new idea to reduce the solidity of low-pressure turbine (LPT) blade cascades, while remain the structural integrity of LPT blade. Aerodynamic performance of a low solidity LPT cascade was improved by increasing blade trailing edge thickness (TET). The solidity of the LPT cascade blade can be reduced by about 12.5% through increasing the TET of the blade without a significant drop in energy efficiency. For the low solidity LPT cascade, increasing the TET can decrease energy loss by 23.30% and increase the flow turning angle by 1.86% for Reynolds number (Re) of 25,000 and freestream turbulence intensities (FSTI) of 2.35%. The flow control mechanism governing behavior around the trailing edge of an LPT cascade is also presented. The results show that appropriate TET is important for the optimal design of high-lift load LPT blade cascades.

  1. A computer program for wing subsonic aerodynamic performance estimates including attainable thrust and vortex lift effects

    Science.gov (United States)

    Carlson, H. W.; Walkley, K. B.

    1982-01-01

    Numerical methods incorporated into a computer program to provide estimates of the subsonic aerodynamic performance of twisted and cambered wings of arbitrary planform with attainable thrust and vortex lift considerations are described. The computational system is based on a linearized theory lifting surface solution which provides a spanwise distribution of theoretical leading edge thrust in addition to the surface distribution of perturbation velocities. The approach used relies on a solution by iteration. The method also features a superposition of independent solutions for a cambered and twisted wing and a flat wing of the same planform to provide, at little additional expense, results for a large number of angles of attack or lift coefficients. A previously developed method is employed to assess the portion of the theoretical thrust actually attainable and the portion that is felt as a vortex normal force.

  2. Effects of flexibility on aerodynamic performance of delta wings with different sweep angles

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Force measurement and surface oil flow visualization experiments were conducted in a wind tunnel to investigate the effects of flexibility on aerodynamic performance of delta wings with different sweep angles.The experimental results indicate that the maximum lift coefficient is increased and the stall angle is delayed as the sweep angle increases for both rigid and flexible wings.It is also found that the maximum lift coefficients of the flexible wings with a sweep angle from 35° to 50° are higher than those of the rigid ones.The increment of the maximum lift coefficient in particular achieves 32.9% compared with the case without lift enhancement for the 40° flexible delta wing.Moreover,the surface oil flow visualization experiments show that the stall of the flexible wing of the moderate low sweep angle is accompanied by helical flow structure,while the vortex bursting appears on the corresponding rigid wing.

  3. High Humidity Aerodynamic Effects Study on Offshore Wind Turbine Airfoil/Blade Performance through CFD Analysis

    Directory of Open Access Journals (Sweden)

    Weipeng Yue

    2017-01-01

    Full Text Available Damp air with high humidity combined with foggy, rainy weather, and icing in winter weather often is found to cause turbine performance degradation, and it is more concerned with offshore wind farm development. To address and understand the high humidity effects on wind turbine performance, our study has been conducted with spread sheet analysis on damp air properties investigation for air density and viscosity; then CFD modeling study using Fluent was carried out on airfoil and blade aerodynamic performance effects due to water vapor partial pressure of mixing flow and water condensation around leading edge and trailing edge of airfoil. It is found that the high humidity effects with water vapor mixing flow and water condensation thin film around airfoil may have insignificant effect directly on airfoil/blade performance; however, the indirect effects such as blade contamination and icing due to the water condensation may have significant effects on turbine performance degradation. Also it is that found the foggy weather with microwater droplet (including rainy weather may cause higher drag that lead to turbine performance degradation. It is found that, at high temperature, the high humidity effect on air density cannot be ignored for annual energy production calculation. The blade contamination and icing phenomenon need to be further investigated in the next study.

  4. Comparative aerodynamic performance of flapping flight in two bat species using time-resolved wake visualization.

    Science.gov (United States)

    Muijres, Florian T; Johansson, L Christoffer; Winter, York; Hedenström, Anders

    2011-10-07

    Bats are unique among extant actively flying animals in having very flexible wings, controlled by multi-jointed fingers. This gives the potential for fine-tuned active control to optimize aerodynamic performance throughout the wingbeat and thus a more efficient flight. But how bat wing performance scales with size, morphology and ecology is not yet known. Here, we present time-resolved fluid wake data of two species of bats flying freely across a range of flight speeds using stereoscopic digital particle image velocimetry in a wind tunnel. From these data, we construct an average wake for each bat species and speed combination, which is used to estimate the flight forces throughout the wingbeat and resulting flight performance properties such as lift-to-drag ratio (L/D). The results show that the wake dynamics and flight performance of both bat species are similar, as was expected since both species operate at similar Reynolds numbers (Re) and Strouhal numbers (St). However, maximum L/D is achieved at a significant higher flight speed for the larger, highly mobile and migratory bat species than for the smaller non-migratory species. Although the flight performance of these bats may depend on a range of morphological and ecological factors, the differences in optimal flight speeds between the species could at least partly be explained by differences in their movement ecology.

  5. Solar cooling system performance, Frenchman's Reef Hotel, Virgin Islands

    Science.gov (United States)

    Harber, H.

    1981-01-01

    The operational and thermal performance of a variety of solar systems are described. The Solar Cooling System was installed in a hotel at St. Thomas, U. S. Virgin Islands. The system consists of the evacuated glass tube collectors, two 2500 gallon tanks, pumps, computerized controller, a large solar optimized industrial sized lithium bromide absorption chiller, and associated plumbing. Solar heated water is pumped through the system to the designed public areas such as lobby, lounges, restaurant and hallways. Auxiliary heat is provided by steam and a heat exchanger to supplement the solar heat.

  6. Thermal Performance Testing of EMU and CSAFE Liquid Cooling Garments

    Science.gov (United States)

    Rhodes, Richard; Bue, Grant; Hakam, Mark; Radford, Tamara

    2013-01-01

    Future exploration missions require the development of a new liquid cooling garment (LCG) that offers greater system reliability, is more comfortable, and maximizes thermal performance. To inform the development of a future LCG a thermal performance test was conducted to evaluate three factors: (1) the effect of the thermal comfort undergarment (TCU) on tactile and thermal comfort, (2) the comparable thermal performance of an CSAFE developed engineering evaluation unit (EEU) LCG, which uses a commercial-off-the-shelf (COTS) wicking garment as the base, and (3) the performance of a torso or upper body only LCG configuration to evaluate a proposed auxiliary loop configuration. To evaluate the thermal performance of each configuration a metabolic suit test was conducted, utilizing suited subjects to generate metabolic heat by walking on a treadmill at various speeds. Three (3) test subjects of similar height and weight produced a metabolic load for five tests by either resting (300-600 BTU/hr), walking at a slow pace (1200 BTU/hr), and walking at a brisk pace (2200 BTU/hr). During the test, data was collected that would allow us to track the heat transfer to the LCG and ventilation system to determine the thermal performance of the LCG configurations. Four different test configurations were tested, with one configuration tested twice. The test results show that the CSAFE EEU LCG and EMU LCG had comparable performance. The testing also showed that an auxiliary loop LCG, sized similarly to the shirt-only configuration, should provide adequate cooling for contingency scenarios. Finally, the testing showed the previous analysis that assumed a UA deterioration from the TCU was too conservative and the TCU may prove to be acceptable for future development with additional analysis and testing.

  7. Performance enhancement of PV cells through micro-channel cooling

    Directory of Open Access Journals (Sweden)

    Muzaffar Ali

    2015-11-01

    Full Text Available Efficiency of a PV cell is strongly dependent on its surface temperature. The current study is focused to achieve maximum efficiency of PV cells even in scorching temperatures in hot climates like Pakistan where the cell surface temperatures can even rise up to around 80 ℃. The study includes both the CFD and real time experimental investigations of a solar panel using micro channel cooling. Initially, CFD analysis is performed by developing a 3D model of a Mono-Crystalline cell with micro-channels to analyze cell surface temperature distribution at different irradiance and water flow rates. Afterwards, an experimental setup is developed for performance investigations under the real conditions of an open climate of a Pakistan's city, Taxila. Two 35W panels are manufactured for the experiments; one is based on the standard manufacturing procedure while other cell is developed with 4mm thick aluminum sheet having micro-channels of cross-section of 1mm by 1mm. The whole setup also includes different sensors for the measurement of solar irradiance, cell power, surface temperature and water flow rates. The experimental results show that PV cell surface temperature drop of around 15 ℃ is achieved with power increment of around 14% at maximum applied water flow rate of 3 LPM. Additionally, a good agreement is also found between CFD and experimental results. Therefore, that study clearly shows that a significant performance improvement of PV cells can be achieved through the proposed cell cooling technique.

  8. Effect of blade pitch angle on aerodynamic performance of straight-bladed vertical axis wind turbine

    Institute of Scientific and Technical Information of China (English)

    张立勋; 梁迎彬; 刘小红; 郭健

    2014-01-01

    Wind energy is one of the most promising renewable energy sources, straight-bladed vertical axis wind turbine (S-VAWT) appears to be particularly promising for the shortage of fossil fuel reserves owing to its distinct advantages, but suffers from poor self-starting and low power coefficient. Variable-pitch method was recognized as an attractive solution to performance improvement, thus majority efforts had been devoted into blade pitch angle effect on aerodynamic performance. Taken into account the local flow field of S-VAWT, mathematical model was built to analyze the relationship between power outputs and pitch angle. Numerical simulations on static and dynamic performances of blade were carried out and optimized pitch angle along the rotor were presented. Comparative analyses of fixed pitch and variable-pitch S-VAWT were conducted, and a considerable improvement of the performance was obtained by the optimized blade pitch angle, in particular, a relative increase of the power coefficient by more than 19.3%. It is further demonstrated that the self-starting is greatly improved with the optimized blade pitch angle.

  9. Neck-cooling improves repeated sprint performance in the heat

    Directory of Open Access Journals (Sweden)

    Caroline eSunderland

    2015-11-01

    Full Text Available The present study evaluated the effect of neck-cooling during exercise on repeated sprint ability in a hot environment. Seven team-sport playing males completed two experimental trials involving repeated sprint exercise (5 x 6 s before and after two 45 min bouts of a football specific intermittent treadmill protocol in the heat (33.0  0.2 ºC; 53 ± 2% relative humidity. Participants wore a neck-cooling collar in one of the trials (CC. Mean power output and peak power output declined over time in both trials but were higher in CC (540 ± 99 v 507 ± 122W, d = 0.32; 719 ± 158 v 680 ± 182 W, d = 0.24 respectively. The improved power output was particularly pronounced (d = 0.51 – 0.88 after the 2nd 45 min bout but the CC had no effect on % fatigue. The collar lowered neck temperature and the thermal sensation of the neck (P 0.05. There were no trial differences but interaction effects were demonstrated for prolactin concentration and rating of perceived exertion (RPE. Prolactin concentration was initially higher in the collar cold trial and then was lower from 45 minutes onwards (interaction trial x time P=0.04. RPE was lower during the football intermittent treadmill protocol in the collar cold trial (interaction trial x time P = 0.01. Neck-cooling during exercise improves repeated sprint performance in a hot environment without altering physiological or neuroendocrinological responses. RPE is reduced and may partially explain the performance improvement.

  10. Numerical and experimental investigation on aerodynamic performance of small axial flow fan with hollow blade root

    Science.gov (United States)

    Li, Zhang; Jin, Yingzi; Huashu, Dou; Yuzhen, Jin

    2013-10-01

    To reduce the influence of adverse flow conditions at the fan hub and improve fan aerodynamic performance, a modification of conventional axial fan blades with numerical and experimental investigation is presented. Hollow blade root is manufactured near the hub. The numerical and experimental results show that hollow blade root has some effect on the static performance. Static pressure of the modified fan is generally the same with that of the datum fan, while, the efficiency curve of the modified fan has a different trend with that of the datum fan. The highest efficiency of the modified fan is 10% greater than that of the datum fan. The orthogonal experimental results of fan noise show that hollow blade root is a feasible method of reducing fan noise, and the maximum value of noise reduction is about 2 dB. The factors affecting the noise reduction of hollow blade root are in the order of importance as follows: hollow blade margin, hollow blade height and hollow blade width. The much smoother pressure distribution of the modified fan than that of the datum fan is the main mechanism of noise reduction of hollow blade root. The research results will provide the proof of the parameter optimization and the structure design for high performance and low noise small axial fans.

  11. Conjugate heat transfer investigation on the cooling performance of air cooled turbine blade with thermal barrier coating

    Science.gov (United States)

    Ji, Yongbin; Ma, Chao; Ge, Bing; Zang, Shusheng

    2016-08-01

    A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera. Besides, conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison. The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant, and spatial difference is also discussed. Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest. The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path. Thermal barrier effects of the coating vary at different regions of the blade surface, where higher internal cooling performance exists, more effective the thermal barrier will be, which means the thermal protection effect of coatings is remarkable in these regions. At the designed mass flow ratio condition, the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface, while this value is 0.09 on the suction side.

  12. Aerodynamic and Performance Behavior of a Three-Stage High Efficiency Turbine at Design and Off-Design Operating Points

    Directory of Open Access Journals (Sweden)

    M. T. Schobeiri

    2004-01-01

    Full Text Available This article deals with the aerodynamic and performance behavior of a three-stage high pressure research turbine with 3-D curved blades at its design and off-design operating points. The research turbine configuration incorporates six rows beginning with a stator row. Interstage aerodynamic measurements were performed at three stations, namely downstream of the first rotor row, the second stator row, and the second rotor row. Interstage radial and circumferential traversing presented a detailed flow picture of the middle stage. Performance measurements were carried out within a rotational speed range of 75% to 116% of the design speed. The experimental investigations have been carried out on the recently established multi-stage turbine research facility at the Turbomachinery Performance and Flow Research Laboratory, TPFL, of Texas A&M University.

  13. Effects of Axial Non-uniform Tip Clearances on Aerodynamic Performance of a Transonic Axial Compressor

    Institute of Scientific and Technical Information of China (English)

    Hongwei MA; Baihe LI

    2008-01-01

    This paper presents a numerical investigation of effects of axial non-uniform tip clearances on the aerodynamic performance of a transonic axial compressor rotor (NASA Rotor 37). The three-dimensional steady flow field within the rotor passage was simulated with the datum tip clearance of 0.356 mm at the design wheel speed of 17188.7 rpm. The simulation results are well consistent with the measurement results, which verified the numeri-cal method. Then the three-dimensional steady flow field within the rotor passage was simulated respectively with different axial non-uniform tip clearances. The calculation results showed that optimal axial non-uniform tip clearances could improve the compressor performance, while the efficiency and the pressure ratio of the com-pressor were increased. The flow mechanism is that the axial non-uniform tip clearance can weaken the tip leak-age vortex, blow down low-energy fluids in boundary layers and reduce both flow blockage and tip loss.

  14. The aerodynamic design and performance of the General Electric/NASA EEE fan. [Energy Efficient Engine

    Science.gov (United States)

    Sullivan, T. J.; Hager, R. D.

    1983-01-01

    The aerodynamic design and test results of the fan and quarter-stage component for the GE/NASA Energy Efficient Engine (EEE) are presented. The fan is a high bypass ratio, single-stage design having 32 part-span shrouded rotor blades, coupled with a unique quarter-stage arrangement that provides additional core-stream pressure ratio and particle separation. The fan produces a bypass pressure ratio of 1.65 at the exit of the low aspect ratio vane/frame and a core-stream pressure ratio of 1.67 at the entrance to the core frame struts. The full-scale fan vehicle was instrumented, assembled and tested as a component in November 1981. Performance mapping was conducted over a range of speeds and bypass ratios using individually-controlled bypass and core-stream discharge valves. The fan bypass and core-stream test data showed excellent results, with the fan exceeding all performance goals at the important engine operating conditions.

  15. Effects of inlet circumferential fluctuation on the sweep aerodynamic performance of axial fans/compressors

    Science.gov (United States)

    Gui, Xingmin; Zhu, Fang; Wan, Ke; Jin, Donghai

    2013-10-01

    Swept blades have been widely used in the transonic fan/compressor of aircraft engines with the aids of 3D CFD simulation since the design concept of controlling the shock structure was firstly proposed and successfully tested by Dr. Wennerstrom in the 1980s. However, some disadvantage phenomenon has also been induced by excessively 3D blade geometries on the structure stress insufficiency, vibration and reliability. Much confusion in the procedure of design practice leading us to recognize a new view on the flow mechanism of sweep aerodynamical induction: the new radial equilibrium established by the influence of inlet circumferential fluctuation (CF) changes the inlet flows of blading and induces the performance modification of axial fans/compressors blade. The view is verified by simplified models through numerical simulation and circumferentially averaged analysis in the present paper. The results show that the CF source items which originate from design parameters, such as the spanwise distributions of the loading and blading geometries, contribute to the changing of averaged incidence spanwise distribution, and further more affect the performance of axial fans/compressors with swept blades.

  16. Computational Analysis of the 2415-3S Airfoil Aerodynamic Performance

    Directory of Open Access Journals (Sweden)

    Luis Velázquez-Araque

    2014-02-01

    Full Text Available This paper deals with the numerical simulation of the two-dimensional, incompressible, steady air flow past an airfoil for a solar powered unmanned aerial vehicle (UAV with internal propulsion system. This airfoil results from a NACA 2415 four digits family base airfoil modification [7] and has a propulsive outlet with the shape of a step on the suction surface. The analysis involved the airfoil's aerodynamic performance which meant obtaining lift, drag and pitching moment coefficient curves as a function of the angle of attack (AOA for the condition where the engine of the UAV is turned off called the gliding condition and also for the blowing propulsive condition by means computational fluid dynamics. The computational domain has been discretised using a structured mesh of 188 x 200 tetrahedral elements. The RNG k-Ε model is utilized to describe the turbulent flow process as it was followed in [5]. The simulations were held at a Reynolds number of 300000. Results allowed obtaining lift and drag forces and pitching moment coefficient and also the location of the separation and reattachment points in some cases by means of the wall shear stress on the suction surface as well as velocity contours and streamlines for both conditions at different angles of attack, from 0 to 16 degrees with the smallest increment of 4 degrees. Finally, results from both cases were compared and the influence of the propulsive flow on the aerodynamic characteristics of the airfoil has been analysed turning out that it improves significantly the performance of the airfoil reaching values up to 1,8 times in terms of lift at high angles of attack. [5] Rhie C.M., Chow W.L., Numerical Study of the Turbulent Flow Past an Airfoil with Trailing Edge Separation, AIAA Journal, Vol. 21, No. 11, 1983. [7] Velazquez L., Nožička J, Kulhanek R., Oil and Smoke Flow Visualization past Two-Dimensional Airfoils for an Unmanned Aerial Vehicle, in The 11th Asian Symposium of

  17. Cooling performance test of the superconducting fault current limiter

    Energy Technology Data Exchange (ETDEWEB)

    Yeom, H.; Hong, Y. J.; Ko, J.; In, S.; Kim, H. B.; Park, S. J. [Korea Institute ofMachinery and Materials, Daejeon (Korea, Republic of); Kim, H.; Kim, H. R. [Korea Electric Power Corporation Research Institute, Daejeon (Korea, Republic of)

    2014-12-15

    The superconducting fault current limiter (SFCL) is an electrical power system device that detects the fault current automatically and limits the magnitude of the current below a certain safety level. The SFCL module does not have any electrical resistance below the critical temperature, which facilitates lossless power transmission in the electric power system. Once given the fault current, however, the superconducting conductor exhibits extremely high electrical resistance, and the magnitude of the current is accordingly limited to a low value. Therefore, SFCL should be maintained at a temperature below the critical temperature, which justifies the cryogenic cooling system as a mandatory component. This report is a study which reported on the cooling system for the 154 kV-class hybrid SFCL owned by Korea Electric Power Corporation (KEPCO). Using the cryocooler, the temperature of liquid nitrogen (LN2) was lowered to 71 K. The cryostat was pressurized to 5 bars to improve the dielectric strength of nitrogen and suppress nitrogen bubble foaming during operation of SFCL. The SFCL module was immersed in the liquid nitrogen of the cryostat to maintain the superconducting state. The performance test results of the key components such as cryocooler, LN2 circulation pump, cold box, and pressure builder are shown in this paper.

  18. Parametric Fuselage Geometry Generation and Aerodynamic Performance Prediction in Preliminary Rotorcraft Design

    OpenAIRE

    Kunze, Philipp

    2013-01-01

    The creation of an integrated rotorcraft conceptual and preliminary design framework at DLR involved the development of geometry and fuselage aerodynamics modules at the Institute of Aerodynamics and Flow Technology. After a short revision of the RIDE rotorcraft design environment architecture this paper focuses on the implementation of these disciplinary modules. The aim of the geometry module is to bridge the gap between conceptual and preliminary design and to allow for geometry parameter ...

  19. Detectors with Improved Near-to-Mid IR Performance and Reduced Cooling Requirements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This program will develop an ultra-high performance infrared detector manufacturing technology with improved performance and cost effectiveness, and reduced cooling...

  20. Synergetic Optimization of Missile Shapes for Aerodynamic and Radar Cross-Section Performance Based on Multi- objective Evolutionary Algorithm

    Institute of Scientific and Technical Information of China (English)

    刘洪

    2004-01-01

    A multiple-objective evolutionary algorithm (MOEA) with a new Decision Making (DM) scheme for MOD of conceptual missile shapes was presented, which is contrived to determine suitable tradeoffs from Pareto optimal set using interactive preference articulation. There are two objective functions, to maximize ratio of lift to drag and to minimize radar cross-section (RCS) value. 3D computational electromagnetic solver was used to evaluate RCS, electromagnetic performance. 3D Navier-Stokes flow solver was adopted to evaluate aerodynamic performance. A flight mechanics solver was used to analyze the stability of the missile. Based on the MOEA, a synergetic optimization of missile shapes for aerodynamic and radar cross-section performance is completed. The results show that the proposed approach can be used in more complex optimization case of flight vehicles.

  1. Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

    Science.gov (United States)

    Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

    2015-01-01

    The measured aerodynamic performance of a compact, high work-factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90deg-bend, and exit guide vane is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level is reported for operation between 70 to 105 percent of design corrected speed, with subcomponent (impeller, diffuser, and exit-guide-vane) flow field measurements presented and discussed at the 100 percent design-speed condition. Individual component losses from measurements are compared with pre-test CFD predictions on a limited basis.

  2. Aerodynamic force generation, performance and control of body orientation during gliding in sugar gliders (Petaurus breviceps).

    Science.gov (United States)

    Bishop, Kristin L

    2007-08-01

    Gliding has often been discussed in the literature as a possible precursor to powered flight in vertebrates, but few studies exist on the mechanics of gliding in living animals. In this study I analyzed the 3D kinematics of sugar gliders (Petaurus breviceps) during short glides in an enclosed space. Short segments of the glide were captured on video, and the positions of marked anatomical landmarks were used to compute linear distances and angles, as well as whole body velocities and accelerations. From the whole body accelerations I estimated the aerodynamic forces generated by the animals. I computed the correlations between movements of the limbs and body rotations to examine the control of orientation during flight. Finally, I compared these results to those of my earlier study on the similarly sized and distantly related southern flying squirrel (Glaucomys volans). The sugar gliders in this study accelerated downward slightly (1.0+/-0.5 m s(-2)), and also accelerated forward (2.1+/-0.6 m s(-2)) in all but one trial, indicating that the body weight was not fully supported by aerodynamic forces and that some of the lift produced forward acceleration rather than just balancing body weight. The gliders used high angles of attack (44.15+/-3.12 degrees ), far higher than the angles at which airplane wings would stall, yet generated higher lift coefficients (1.48+/-0.18) than would be expected for a stalled wing. Movements of the limbs were strongly correlated with body rotations, suggesting that sugar gliders make extensive use of limb movements to control their orientation during gliding flight. In addition, among individuals, different limb movements were associated with a given body rotation, suggesting that individual variation exists in the control of body rotations. Under similar conditions, flying squirrels generated higher lift coefficients and lower drag coefficients than sugar gliders, yet had only marginally shallower glides. Flying squirrels have a

  3. A Numerical Study of Aerodynamic Performance and Noise of a Bionic Airfoil Based on Owl Wing

    Directory of Open Access Journals (Sweden)

    Xiaomin Liu

    2014-08-01

    Full Text Available Noise reduction and efficiency enhancement are the two important directions in the development of the multiblade centrifugal fan. In this study, we attempt to develop a bionic airfoil based on the owl wing and investigate its aerodynamic performance and noise-reduction mechanism at the relatively low Reynolds number. Firstly, according to the geometric characteristics of the owl wing, a bionic airfoil is constructed as the object of study at Reynolds number of 12,300. Secondly, the large eddy simulation (LES with the Smagorinsky model is adopted to numerically simulate the unsteady flow fields around the bionic airfoil and the standard NACA0006 airfoil. And then, the acoustic sources are extracted from the unsteady flow field data, and the Ffowcs Williams-Hawkings (FW-H equation based on Lighthill's acoustic theory is solved to predict the propagation of these acoustic sources. The numerical results show that the lift-to-drag ratio of bionic airfoil is higher than that of the traditional NACA 0006 airfoil because of its deeply concave lower surface geometry. Finally, the sound field of the bionic airfoil is analyzed in detail. The distribution of the A-weighted sound pressure levels, the scaled directivity of the sound, and the distribution of dP/dt on the airfoil surface are provided so that the characteristics of the acoustic sources could be revealed.

  4. On the influence of airfoil deviations on the aerodynamic performance of wind turbine rotors

    Science.gov (United States)

    Winstroth, J.; Seume, J. R.

    2016-09-01

    The manufacture of large wind turbine rotor blades is a difficult task that still involves a certain degree of manual labor. Due to the complexity, airfoil deviations between the design airfoils and the manufactured blade are certain to arise. Presently, the understanding of the impact of manufacturing uncertainties on the aerodynamic performance is still incomplete. The present work analyzes the influence of a series of airfoil deviations likely to occur during manufacturing by means of Computational Fluid Dynamics and the aeroelastic code FAST. The average power production of the NREL 5MW wind turbine is used to evaluate the different airfoil deviations. Analyzed deviations include: Mold tilt towards the leading and trailing edge, thick bond lines, thick bond lines with cantilever correction, backward facing steps and airfoil waviness. The most severe influences are observed for mold tilt towards the leading and thick bond lines. By applying the cantilever correction, the influence of thick bond lines is almost compensated. Airfoil waviness is very dependent on amplitude height and the location along the surface of the airfoil. Increased influence is observed for backward facing steps, once they are high enough to trigger boundary layer transition close to the leading edge.

  5. Effects of geometry on slot-jet film cooling performance

    Energy Technology Data Exchange (ETDEWEB)

    Hyams, D.G.; McGovern, K.T.; Leylek, J.H. [Clemson Univ., SC (United States)

    1995-10-01

    The physics of the film cooling process for shaped, inclined slot-jets with realistic slot-length-to-width ratios (L/s) is studied for a range of blowing ratio (M) and density ratio (DR) parameters typical of gas turbine operations. For the first time in the open literature, the effect of inlet and exit shaping of the slot-jet on both flow and thermal field characteristics is isolated, and the dominant mechanisms responsible for differences in these characteristics are documented. A previously documented computational methodology was applied for the study of four distinct configurations: (1) slot with straight edges and sharp corners (reference case); (2) slot with shaped inlet region; (3) slot with shaped exit region; and (4) slot with both shaped inlet and exit regions. Detailed field results as well as surface phenomena involving adiabatic film effectiveness ({eta}) and heat transfer coefficient (h) are presented. It is demonstrated that both {eta} and h results are vital in the proper assessment of film cooling performance. All simulations were carried out using a multi-block, unstructured/adaptive grid, fully explicit, time-marching solver with multi-grid, local time stepping, and residual smoothing type acceleration techniques. Special attention was paid to and full documentation provided for: (1) proper modeling of the physical phenomena; (2) exact geometry and high quality grid generation techniques; (3) discretization schemes; and (4) turbulence modeling issues. The key parameters M and DR were varied from 1.0 to 2.0 and 1.5 to 2.0, respectively, to show their influence. Simulations were repeated for slot length-to-width ratio (L/s) of 3.0 and 4.5 in order to explain the effects of this important parameter. Additionally, the performance of two popular turbulence models, standard k-F, and RNG k-E, were studied to establish their ability to handle highly elliptic jet/crossflow interaction type processes.

  6. Effect of Half Time Cooling on Thermoregulatory Responses and Soccer-Specific Performance Tests

    Directory of Open Access Journals (Sweden)

    Yang Zhang

    2014-03-01

    Full Text Available This study examined two active coolings (forearm and hand cooling, and neck cooling during a simulated half-time recovery on thermoregulatory responses and subsequent soccer-specific exercise performance. Following a 45-min treadmill run in the heat, participants (N=7 undertook 15-min recovery with either passive cooling, forearm and hand cooling, or neck cooling in a simulated cooled locker room environment. After the recovery, participants performed a 6×15-m sprint test and Yo-Yo Intermittent Recovery Level 1 test (YYIR1 in a temperate environment. During the 15-min recovery, rectal temperature fell significantly (p<0.05. Neither active coolings induced further reduction in rectal temperature compared to passive cooling. No effect of active coolings was found in repeated sprint test. However, neck cooling reduced (p<0.05 the thermal sensation (TS compared to passive cooling during the 15-min recovery. Active coolings attenuated (p<0.05 the sweat rate compared to passive cooling: 1.2±0.3 l•h-1 vs. 0.8±0.1 l•h-1 vs. 0.8±0.3 l•h-1, for passive cooling, forearm and hand cooling, and neck cooling, respectively. For passive cooling, elevated sweat rate resulted in higher (p<0.05 dehydration (2.1±0.3% compared to neck cooling (1.5±0.3% and forearm and hand cooling (1.4±0.3%. YYIR1 was improved (p<0.05 following forearm and hand cooling (869±320 m and neck cooling (814±328 m compared to passive cooling (654±311 m. Neck cooling (4.6±0.6 reduced (p=0.03 the session TS compared to passive cooling (5.3±0.5. These results suggest that active coolings effectively improved comfort and sweating response, which delayed exercise-heat induced performance diminish during a second bout of exercise.

  7. Thermal Performance Testing of EMU and OSS Liquid Cooling Garments

    Science.gov (United States)

    Rhodes, Richard; Bue, Grant; Hakam, Mary

    2012-01-01

    A test was conducted to evaluate three factors influencing the thermal performance of liquid cooling garments (LCG): (1) the comparable thermal performance of an Oceaneering developed engineering evaluation unit (EEU) prototype LDG, (2) the effect of the thermal comfort undergarment (TCU), and (3) the performance of a torso or upper body only LCG configuration. To evaluate the thermal performance of each configuration a metabolic test was conducted, utilizing suited subjects to generate the metabolic heat. For this study three (3) test subjects of similar health and weight produced a metabolic load on the LDG configuration by either resting (300-600 BTU/hr), walking at a slow pace (1200 BRU/hr), and walking at a brisk pace (2200 BTU/hr), as outlined in Figure 1, the metabolic profile. During the test, oxygen consumption, heart rate, relative humidity, air flow, inlet and outlet air pressure, inlet and outlet air temperature, delta air temperature, water flow (100 lb/hr), inlet water temperature (64 F), delta water temperature, water pressure, core body temperature, skin temperature, and sweat loss data was recorded. Four different test configurations were tested, with one configuration tested twice, as outlined in Table 1. The test was conducted with the suit subjects wearing the Demonstrator Suit, pressurized to vent pressure (approximately 0.5 psig). The demonstrator suit has an integrated ventilation duct system and was used to create a relevant environment with a captured ventilation return, an integrated vent tree, and thermal insulation from the environment.

  8. Enhancing the performance of photovoltaic panels by water cooling

    Directory of Open Access Journals (Sweden)

    K.A. Moharram

    2013-12-01

    Full Text Available The objective of the research is to minimize the amount of water and electrical energy needed for cooling of the solar panels, especially in hot arid regions, e.g., desert areas in Egypt. A cooling system has been developed based on water spraying of PV panels. A mathematical model has been used to determine when to start cooling of the PV panels as the temperature of the panels reaches the maximum allowable temperature (MAT. A cooling model has been developed to determine how long it takes to cool down the PV panels to its normal operating temperature, i.e., 35 °C, based on the proposed cooling system. Both models, the heating rate model and the cooling rate model, are validated experimentally. Based on the heating and cooling rate models, it is found that the PV panels yield the highest output energy if cooling of the panels starts when the temperature of the PV panels reaches a maximum allowable temperature (MAT of 45 °C. The MAT is a compromise temperature between the output energy from the PV panels and the energy needed for cooling.

  9. COOLING FAN AND SYSTEM PERFORMANCE AND EFFICIENCY IMPROVEMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Ronald Dupree

    2005-07-31

    Upcoming emissions regulations (Tiers 3, 4a and 4b) are imposing significantly higher heat loads on the cooling system than lesser regulated machines. This work was a suite of tasks aimed at reducing the parasitic losses of the cooling system, or improving the design process through six distinct tasks: 1. Develop an axial fan that will provide more airflow, with less input power and less noise. The initial plan was to use Genetic Algorithms to do an automated fan design, incorporating forward sweep for low noise. First and second generation concepts could not meet either performance or sound goals. An experienced turbomachinery designer, using a specialized CFD analysis program has taken over the design and has been able to demonstrate a 5% flow improvement (vs 10% goal) and 10% efficiency improvement (vs 10% goal) using blade twist only. 2. Fan shroud developments, using an 'aeroshroud' concept developed at Michigan State University. Performance testing at Michigan State University showed the design is capable of meeting the goal of a 10% increase in flow, but over a very narrow operating range of fan performance. The goal of 10% increase in fan efficiency was not met. Fan noise was reduced from 0 to 2dB, vs. a goal of 5dB at constant airflow. The narrow range of fan operating conditions affected by the aeroshroud makes this concept unattractive for further development at this time 3. Improved axial fan system modeling is needed to accommodate the numbers of cooling systems to be redesigned to meet lower emissions requirements. A CFD fan system modeling guide has been completed and transferred to design engineers. Current, uncontrolled modeling practices produce flow estimates in some cases within 5% of measured values, and in some cases within 25% of measured values. The techniques in the modeling guide reduced variability to the goal of + 5% for the case under study. 4. Demonstrate the performance and design versatility of a high performance fan. A

  10. Assessment Of The Aerodynamic And Aerothermodynamic Performance Of The USV-3 High-Lift Re-Entry Vehicle

    Science.gov (United States)

    Pezzella, Giuseppe; Richiello, Camillo; Russo, Gennaro

    2011-05-01

    This paper deals with the aerodynamic and aerothermodynamic trade-off analysis carried out with the aim to design a hypersonic flying test bed (FTB), namely USV3. Such vehicle will have to be launched with a small expendable launcher and shall re-enter the Earth atmosphere allowing to perform several experiments on critical re-entry phenomena. The demonstrator under study is a re-entry space glider characterized by a relatively simple vehicle architecture able to validate hypersonic aerothermodynamic design database and passenger experiments, including thermal shield and hot structures. Then, a summary review of the aerodynamic characteristics of two FTB concepts, compliant with a phase-A design level, has been provided hereinafter. Indeed, several design results, based both on engineering approach and computational fluid dynamics, are reported and discussed in the paper.

  11. Computational assessment of the DeepWind aerodynamic performance with different blade and airfoil configurations

    DEFF Research Database (Denmark)

    Bedon, Gabriele; Schmidt Paulsen, Uwe; Aagaard Madsen, Helge

    2017-01-01

    An aerodynamic improvement of the DeepWind rotor is conducted adopting different rotor geometries and solutions with respect to the original configuration while keeping the comparison as fair as possible. The objective of this work is to find the most suitable configuration in order to maximize t...

  12. Effects of perforation number of blade on aerodynamic performance of dual-rotor small axial flow fans

    Science.gov (United States)

    Hu, Yongjun; Wang, Yanping; Li, Guoqi; Jin, Yingzi; Setoguchi, Toshiaki; Kim, Heuy Dong

    2015-04-01

    Compared with single rotor small axial flow fans, dual-rotor small axial flow fans is better regarding the static characteristics. But the aerodynamic noise of dual-rotor small axial flow fans is worse than that of single rotor small axial flow fans. In order to improve aerodynamic noise of dual-rotor small axial flow fans, the pre-stage blades with different perforation numbers are designed in this research. The RANS equations and the standard k-ɛ turbulence model as well as the FW-H noise model are used to simulate the flow field within the fan. Then, the aerodynamic performance of the fans with different perforation number is compared and analyzed. The results show that: (1) Compared to the prototype fan, the noise of fans with perforation blades is reduced. Additionally, the noise of the fans decreases with the increase of the number of perforations. (2) The vorticity value in the trailing edge of the pre-stage blades of perforated fans is reduced. It is found that the vorticity value in the trailing edge of the pre-stage blades decreases with the increase of the number of perforations. (3) Compared to the prototype fan, the total pressure rising and efficiency of the fans with perforation blades drop slightly.

  13. Sensitivity of energy and exergy performances of heating and cooling systems to auxiliary components

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2017-01-01

    should be used in design and analysis of the whole heating and cooling systems, in addition to the energy analysis. In this study, water-based (floor heating and cooling, and radiator heating) and air-based (air heating and cooling) heating and cooling systems were compared in terms of their energy use...... and exergy consumption for auxiliary components (pumps and fans). The effects of the auxiliary components on whole system energy and exergy performance were identified. Water-based heating systems required 68% lower auxiliary exergy input than the warm-air heating system with heat recovery, and floor cooling...

  14. Experimental investigations on showerhead cooling on a blunt body

    Energy Technology Data Exchange (ETDEWEB)

    Falcoz, C.; Ott, P. [Ecole Polytechnique Federale de Lausanne (EPFL), Laboratoire de Thermique Appliquee et de Turbomachines (LTT), 1015 Lausanne (Switzerland); Weigand, B. [Institut fuer Thermodynamik der Luft- und Raumfahrt (ITLR), Stuttgart University, Pfaffenwaldring 31, 70569 Stuttgart (Germany)

    2006-04-15

    In modern gas turbines, the turbine airfoil leading edge is currently protected from the hot gases by specific film cooling schemes, so-called showerhead cooling. The present paper shows an experimental study of different showerhead cooling geometries on a blunt body. For these tests, TLC (thermochromatic liquid crystals) have been used for measuring the film cooling performance and the heat transfer. Detailed experimental results for the aerodynamics, the film cooling effectiveness and the heat transfer enhancement are presented for different film cooling geometries. (author)

  15. Effects of wing shape, aspect ratio and deviation angle on aerodynamic performance of flapping wings in hover

    Science.gov (United States)

    Shahzad, Aamer; Tian, Fang-Bao; Young, John; Lai, Joseph C. S.

    2016-11-01

    This numerical study is focused on assessing the effect on the aerodynamic hovering performance of wing shapes defined by the radius of the first moment of the wing area ( r 1 ¯ ) and aspect ratio (AR). In addition, the effect of introducing a deviation angle in the kinematics is examined. The performance of r 1 ¯ = 0 . 43 , 0.53, and 0.63 wings with AR of 1.5, 2.96, 4.5, and 6.0 is investigated at Reynolds numbers (Re) = 12, 400, and 13 500. The performance trends of the wing shapes have been observed to be independent of Re for both 2-angle and 3-angle kinematics. This is because high suction pressures associated with the leading-edge vortex are predominantly spread in the distal (away from the wing root) and leeward regions (towards the trailing-edge) of high flapping velocities for all the cases. While the deviation angle is detrimental to the production of lift and power economy (PE, defined as the ratio of the mean lift coefficient to the mean aerodynamic power coefficient) at Re = 12 due to strong viscous effects, it improves PE at Re = 400 and 13 500. A high instantaneous angle of attack at the stroke reversal results in high lift peak for 3-angle kinematics but its effect at Re = 400 and 13 500 is attenuated by strong vortical structures on the underside of the wing. Maximum PE is achieved at AR = 2.96, as a low AR wing does not produce enough lift and high AR wings consume more aerodynamic power. Although the lift is maximized using high r 1 ¯ and AR wings, our results show that low r 1 ¯ and high AR wings are best for maximizing PE for a given lift in insects.

  16. Evaluating the catching performance of aerodynamic rain gauges through field comparisons and CFD modelling

    Science.gov (United States)

    Pollock, Michael; Colli, Matteo; Stagnaro, Mattia; Lanza, Luca; Quinn, Paul; Dutton, Mark; O'Donnell, Greg; Wilkinson, Mark; Black, Andrew; O'Connell, Enda

    2016-04-01

    Accurate rainfall measurement is a fundamental requirement in a broad range of applications including flood risk and water resource management. The most widely used method of measuring rainfall is the rain gauge, which is often also considered to be the most accurate. In the context of hydrological modelling, measurements from rain gauges are interpolated to produce an areal representation, which forms an important input to drive hydrological models and calibrate rainfall radars. In each stage of this process another layer of uncertainty is introduced. The initial measurement errors are propagated through the chain, compounding the overall uncertainty. This study looks at the fundamental source of error, in the rainfall measurement itself; and specifically addresses the largest of these, the systematic 'wind-induced' error. Snowfall is outside the scope. The shape of a precipitation gauge significantly affects its collection efficiency (CE), with respect to a reference measurement. This is due to the airflow around the gauge, which causes a deflection in the trajectories of the raindrops near the gauge orifice. Computational Fluid-Dynamic (CFD) simulations are used to evaluate the time-averaged airflows realized around the EML ARG100, EML SBS500 and EML Kalyx-RG rain gauges, when impacted by wind. These gauges have a similar aerodynamic profile - a shape comparable to that of a champagne flute - and they are used globally. The funnel diameter of each gauge, respectively, is 252mm, 254mm and 127mm. The SBS500 is used by the UK Met Office and the Scottish Environmental Protection Agency. Terms of comparison are provided by the results obtained for standard rain gauge shapes manufactured by Casella and OTT which, respectively, have a uniform and a tapered cylindrical shape. The simulations were executed for five different wind speeds; 2, 5, 7, 10 and 18 ms-1. Results indicate that aerodynamic gauges have a different impact on the time-averaged airflow patterns

  17. Aerodynamic performance of two-dimensional, chordwise flexible flapping wings at fruit fly scale in hover flight.

    Science.gov (United States)

    Sridhar, Madhu; Kang, Chang-kwon

    2015-05-06

    Fruit flies have flexible wings that deform during flight. To explore the fluid-structure interaction of flexible flapping wings at fruit fly scale, we use a well-validated Navier-Stokes equation solver, fully-coupled with a structural dynamics solver. Effects of chordwise flexibility on a two dimensional hovering wing is studied. Resulting wing rotation is purely passive, due to the dynamic balance between aerodynamic loading, elastic restoring force, and inertial force of the wing. Hover flight is considered at a Reynolds number of Re = 100, equivalent to that of fruit flies. The thickness and density of the wing also corresponds to a fruit fly wing. The wing stiffness and motion amplitude are varied to assess their influences on the resulting aerodynamic performance and structural response. Highest lift coefficient of 3.3 was obtained at the lowest-amplitude, highest-frequency motion (reduced frequency of 3.0) at the lowest stiffness (frequency ratio of 0.7) wing within the range of the current study, although the corresponding power required was also the highest. Optimal efficiency was achieved for a lower reduced frequency of 0.3 and frequency ratio 0.35. Compared to the water tunnel scale with water as the surrounding fluid instead of air, the resulting vortex dynamics and aerodynamic performance remained similar for the optimal efficiency motion, while the structural response varied significantly. Despite these differences, the time-averaged lift scaled with the dimensionless shape deformation parameter γ. Moreover, the wing kinematics that resulted in the optimal efficiency motion was closely aligned to the fruit fly measurements, suggesting that fruit fly flight aims to conserve energy, rather than to generate large forces.

  18. Experimental investigation of cooling performance of a novel HVAC system combining natural ventilation with diffuse ceiling inlet and TABS

    DEFF Research Database (Denmark)

    Yu, Tao; Heiselberg, Per Kvols; Lei, Bo;

    2015-01-01

    Highlights •An experimental investigation of cooling performance of a combined HVAC system is carried out. •Cooling performance of TABS with and without the influence of diffuse ceiling is analyzed. •Radiant and convective heat transfer coefficients of TABS cooling are studied. •Cooling components...

  19. Design of a high performance low aerodynamic noise axial flow fan

    OpenAIRE

    2007-01-01

    The project starts with a description of the main sources of noise in an axial flow fan for concluding that the thing we should avoid is the trailing edge noise. After that the formulas for designing a fan and an aerodynamics background are presented. Once we get the results of these formulas a low noise optimization is carried on for leading us to a table of results where the main characteristics of design for our fan are obtained. After these tables the design of the fan is obtained with Pr...

  20. High Performance Mars Liquid Cooling and Ventilation Garment Project

    Science.gov (United States)

    Terrier, Douglas; Clayton, Ronald; Whitlock, David; Conger, Bruce

    2015-01-01

    EVA space suit mobility in micro-gravity is enough of a challenge and in the gravity of Mars, improvements in mobility will enable the suited crew member to efficiently complete EVA objectives. The idea proposed is to improve thermal efficiencies of the liquid cooling and ventilation garment (LCVG) in the torso area in order to free up the arms and legs by removing the liquid tubes currently used in the ISS EVA suit in the limbs. By using shaped water tubes that greatly increase the contact area with the skin in the torso region of the body, the heat transfer efficiency can be increased to provide the entire liquid cooling requirement and increase mobility by freeing up the arms and legs. Additional potential benefits of this approach include reduced LCVG mass, enhanced evaporation cooling, increased comfort during Mars EVA tasks, and easing of the overly dry condition in the helmet associated with the Advanced Extravehicular Mobility Unit (EMU) ventilation loop currently under development.

  1. Numerical simulation of the effects of hanging sound absorbers on TABS cooling performance

    DEFF Research Database (Denmark)

    Rage, Nils; Kazanci, Ongun Berk; Olesen, Bjarne W.

    2016-01-01

    to a degradation of the room acoustic comfort. Therefore, challenges arise when this system has to be combined with acoustic requirements. Soffit-hanging sound absorbers embody a promising solution. This study focuses on quantifying their impact on the cooling performance of TABS, assessed by means of the cooling...... simulating a two-person office of 20 m2, with a typical cooling load of 42 W/m2. The results show that covering 60% of the ceiling surface with sound absorbers hanging at 300 mm from the ceiling active deck is expected to reduce the cooling capacity coefficient of TABS by 15.8%. This drops to 25...

  2. Optimizing the performance of desiccant beds for solar-regenerated cooling

    Energy Technology Data Exchange (ETDEWEB)

    Barlow, R.; Collier, K.

    1981-03-01

    Detailed computer simulations as well as a simplified psychrometric analysis are used to determine the increase in cooling system performance that can be realized through the use of nonhomogeneous or staged desiccant beds. A staged bed of four hypothetical desiccants is shown to give a 10% higher cooling capacity than a silica gel bed of the same thickness. Alternatively, the same cooling capacity is produced by a staged bed 37% thinner than the silica gel bed. These effects could be employed to reduce the parasitic power requirements of desiccant cooling systems.

  3. Off-design computer code for calculating the aerodynamic performance of axial-flow fans and compressors

    Science.gov (United States)

    Schmidt, James F.

    1995-01-01

    An off-design axial-flow compressor code is presented and is available from COSMIC for predicting the aerodynamic performance maps of fans and compressors. Steady axisymmetric flow is assumed and the aerodynamic solution reduces to solving the two-dimensional flow field in the meridional plane. A streamline curvature method is used for calculating this flow-field outside the blade rows. This code allows for bleed flows and the first five stators can be reset for each rotational speed, capabilities which are necessary for large multistage compressors. The accuracy of the off-design performance predictions depend upon the validity of the flow loss and deviation correlation models. These empirical correlations for the flow loss and deviation are used to model the real flow effects and the off-design code will compute through small reverse flow regions. The input to this off-design code is fully described and a user's example case for a two-stage fan is included with complete input and output data sets. Also, a comparison of the off-design code predictions with experimental data is included which generally shows good agreement.

  4. Performance Evaluation of a Software Engineering Tool for Automated Design of Cooling Systems in Injection Moulding

    DEFF Research Database (Denmark)

    Jauregui-Becker, Juan M.; Tosello, Guido; van Houten, Fred J.A.M.;

    2013-01-01

    This paper presents a software tool for automating the design of cooling systems for injection moulding and a validation of its performance. Cooling system designs were automatically generated by the proposed software tool and by applying a best practice tool engineering design approach. The two ...

  5. 16 CFR Appendix H to Part 305 - Cooling Performance and Cost for Central Air Conditioners

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Cooling Performance and Cost for Central Air Conditioners H Appendix H to Part 305 Commercial Practices FEDERAL TRADE COMMISSION REGULATIONS UNDER SPECIFIC... Manufacturer's rated cooling capacities (Btu's/hr.) Range of SEER's Low High Single Package Units Central...

  6. Performance Assessment of a Desiccant Cooling System in a CHP Application with an IC Engine

    Energy Technology Data Exchange (ETDEWEB)

    Jalalzadeh-Azar, A. A.; Slayzak, S.; Judkoff, R.; Schaffhauser, T.; DeBlasio, R.

    2005-04-01

    Performance of a desiccant cooling system was evaluated in the context of combined heat and power (CHP). The baseline system incorporated a desiccant dehumidifier, a heat exchanger, an indirect evaporative cooler, and a direct evaporative cooler. The desiccant unit was regenerated through heat recovery from a gas-fired reciprocating internal combustion engine. The system offered sufficient sensible and latent cooling capacities for a wide range of climatic conditions, while allowing influx of outside air in excess of what is typically required for commercial buildings. Energy and water efficiencies of the desiccant cooling system were also evaluated and compared with those of a conventional system. The results of parametric assessments revealed the importance of using a heat exchanger for concurrent desiccant post cooling and regeneration air preheating. These functions resulted in enhancement of both the cooling performance and the thermal efficiency, which are essential for fuel utilization improvement. Two approaches for mixing of the return air and outside air were examined, and their impact on the system cooling performance and thermal efficiency was demonstrated. The scope of the parametric analyses also encompassed the impact of improving the indirect evaporative cooling effectiveness on the overall cooling system performance.

  7. Field evaluation of performance of radiant heating/cooling ceiling panel system

    DEFF Research Database (Denmark)

    Li, Rongling; Yoshidomi, Togo; Ooka, Ryozo;

    2015-01-01

    heating/coolingceiling panel system is used. However, no standard exists for the in situ performance evaluation of radiantheating/cooling ceiling systems; furthermore, no published database is available for comparison. Thus,this study aims to not only clarify the system performance but also to share our...... experience and our resultsfor them to serve as a reference for other similar projects. Here, the system performance in relation toits heating/cooling capacity and thermal comfort has been evaluated. The heat transfer coefficient fromwater to room was 3.7 W/(m2K) and 4.8 W/(m2K) for heating and cooling cases...

  8. Performance of Cooled Cone Grinding Machine in Cocoa Cake Processing

    Directory of Open Access Journals (Sweden)

    Hendy Firmanto

    2015-08-01

    Full Text Available The process of cocoa paste pressing has a function to separate the fatty component of cocoa from its cake. Cocoa paste is further processed into cocoa powder using grinding machine for cocoa cake. The cooled cone type of cocoa grinding machine is used to solve the problem of plug in the maschine caused by melting of fat in cocoa cake due to hot effect as a result of friction in the grinding machine. Grinding machine of cocoa has conical form of cylinder for grinding and stator wall wrapped by source of cold and closed with jacket wool. Research was conducted at Kaliwining Experimental Garden of Indonesian Coffee and Cocoa Research Institute (ICCRI using cocoa cake containing 26.75% originated from Forastero type of cocoa seed. The capacity and recovery of the machine was influenced by space between rotor cylinder and stator wall. Grinding machine operated at cooling temperature of 25.5oC and space between rotor – stator 0.9 cm and the capacity of 187.5 kg/hour with recovery of 200 mesh cocoa powder as much as 24%. The maximum  power of machine required  was 2.5 kW with efficiency of  energy transfer of 97%. Results of proximate analysis showed that there was no change of protein content, but protein and carbohydrate content increased after processing, i.e. from 5.70% and 59.82% into 5.80% and 61.89% respectively.Key words : cocoa cake, cooling, grinding, cocoa powder 

  9. Flightweight radiantly and actively cooled panel: Thermal and structural performance

    Science.gov (United States)

    Shore, C. P.; Nowak, R. J.; Kelly, H. N.

    1982-01-01

    A 2- by 4-ft flightweight panel was subjected to thermal/structural tests representative of design flight conditions for a Mach 6.7 transport and to off-design conditions simulating flight maneuvers and cooling system failures. The panel utilized Rene 41 heat shields backed by a thin layer of insulation to radiate away most of the 12 Btu/ft2-sec incident heating. A solution of ethylene glycol in water circulating through tubes in an aluminum-honeycomb-sandwich panel absorbed the remainder of the incident heating (0.8 Btu/sq ft-sec). The panel successfully withstood (1) 46.7 hr of radiant heating which included 53 thermal cycles and 5000 cycles of uniaxial inplane loading of + or - 1200 lfb/in; (2) simulated 2g-maneuver heating conditions and simulated cooling system failures without excessive temperatures on the structural panel; and (3) the extensive thermal/structural tests and the aerothermal tests reported in NASA TP-1595 without significant damage to the structural panel, coolant leaks, or hot-gas ingress to the structural panel.

  10. APPROACHING CRYOGENIC GE PERFORMANCE WITH PELTIER COOLED CDTE

    Energy Technology Data Exchange (ETDEWEB)

    Khusainov, A. K. (A. Kh.); Iwanczyk, J. S. (Jan S.); Patt, B. E. (Bradley E.); Prirogov, A. M. (Alexandre M.); Vo, Duc T.

    2001-01-01

    A new class of hand-held, portable spectrometers based on large area (lcm2) CdTe detectors of thickness up to 3mm has been demonstrated to produce energy resolution of between 0.3 and 0.5% FWHM at 662 keV. The system uses a charge loss correction circuit for improved efficiency, and detector temperature stabilization to ensure consistent operation of the detector during field measurements over a wide range of ambient temperature. The system can operate continuously for up to 8hrs on rechargeable batteries. The signal output from the charge loss corrector is compatible with most analog and digital spectroscopy amplifiers and multi channel analyzers. Using a detector measuring 11.2 by 9.1 by 2.13 mm3, we have recently been able to obtain the first wide-range plutonium gamma-ray isotopic analysis with other than a cryogenically cooled germanium spectrometer. The CdTe spectrometer is capable of measuring small plutonium reference samples in about one hour, covering the range from low to high burnup. The isotopic analysis software used to obtain these results was FRAM, Version 4 from LANL. The new spectrometer is expected to be useful for low-grade assay, as well as for some in-situ plutonium gamma-ray isotopics in lieu of cryogenically cooled Ge.

  11. System performance and economic analysis of solar-assisted cooling/heating system

    KAUST Repository

    Huang, B.J.

    2011-11-01

    The long-term system simulation and economic analysis of solar-assisted cooling/heating system (SACH-2) was carried out in order to find an economical design. The solar heat driven ejector cooling system (ECS) is used to provide part of the cooling load to reduce the energy consumption of the air conditioner installed as the base-load cooler. A standard SACH-2 system for cooling load 3.5. kW (1. RT) and daily cooling time 10 h is used for case study. The cooling performance is assumed only in summer seasons from May to October. In winter season from November to April, only heat is supplied. Two installation locations (Taipei and Tainan) were examined.It was found from the cooling performance simulation that in order to save 50% energy of the air conditioner, the required solar collector area is 40m2 in Taipei and 31m2 in Tainan, for COPj=0.2. If the solar collector area is designed as 20m2, the solar ejector cooling system will supply about 17-26% cooling load in Taipei in summer season and about 21-27% cooling load in Tainan. Simulation for long-term performance including cooling in summer (May-October) and hot water supply in winter (November-April) was carried out to determine the monthly-average energy savings. The corresponding daily hot water supply (with 40°C temperature rise of water) for 20m2 solar collector area is 616-858L/day in Tainan and 304-533L/day in Taipei.The economic analysis shows that the payback time of SACH-2 decreases with increasing cooling capacity. The payback time is 4.8. years in Tainan and 6.2. years in Taipei when the cooling capacity >10. RT. If the ECS is treated as an additional device used as a protective equipment to avoid overheating of solar collectors and to convert the excess solar heat in summer into cooling to reduce the energy consumption of air conditioner, the payback time is less than 3 years for cooling capacity larger than 3. RT. © 2011 Elsevier Ltd.

  12. Performance test of the cryogenic cooling system for the superconducting fault current limiter

    Science.gov (United States)

    Hong, Yong-Ju; In, Sehwan; Yeom, Han-Kil; Kim, Heesun; Kim, Hye-Rim

    2015-12-01

    A Superconducting Fault Current Limiter is an electric power device which limits the fault current immediately in a power grid. The SFCL must be cooled to below the critical temperature of high temperature superconductor modules. In general, they are submerged in sub-cooled liquid nitrogen for their stable thermal characteristics. To cool and maintain the target temperature and pressure of the sub-cooled liquid nitrogen, the cryogenic cooling system should be designed well with a cryocooler and coolant circulation devices. The pressure of the cryostat for the SFCL should be pressurized to suppress the generation of nitrogen bubbles in quench mode of the SFCL. In this study, we tested the performance of the cooling system for the prototype 154 kV SFCL, which consist of a Stirling cryocooler, a subcooling cryostat, a pressure builder and a main cryostat for the SFCL module, to verify the design of the cooling system and the electric performance of the SFCL. The normal operation condition of the main cryostat is 71 K and 500 kPa. This paper presents tests results of the overall cooling system.

  13. Joint Cooling does not Hinder Athletic Performance during High-intensity Intermittent Exercise.

    Science.gov (United States)

    Kim, H; Lee, D; Choi, H-M; Park, J

    2016-07-01

    We examined the effects of ankle and knee joint cooling on 20-m sprint times and maximal vertical jump heights during high-intensity intermittent exercise. 21 healthy collegiate male basketball (n=14) and handball players (n=7) underwent 3 experimental sessions. Each session consisted of four 15-min quarters of high-intensity intermittent exercises including various intensities of 20-m shuttle running and jumping. A 20-min bilateral joint cooling (ankle, knee, or control-no cooling: in a counterbalanced order) was applied before quarters 1 and 3. After joint cooling, no warm-up activity other than the exercise protocol was given. The 20-m sprint times and maximal vertical jump heights in each experimental session were recorded at baseline (prior to quarter-1) and during each quarter. To test joint cooling effects over time, we performed 3×5 mixed model ANOVAs. Neither ankle nor knee joint cooling changed 20-m sprint times (F8,280=1.45; p=0.18) or maximal vertical jump heights (F8,280=0.76; p=0.64). However, a trend was observed in which joint cooling immediately decreased (quarters 1 and 3) but active warm-up for approximately 20 min improved 20-min sprint times (quarters 2 and 4). Our study suggests that athletic performance such as sprinting and jumping are not altered by joint cooling applied prior to or during high-intensity intermittent exercise.

  14. Cooling Performance Characteristics on Mobile Air-Conditioning System for Hybrid Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Ho-Seong Lee

    2013-01-01

    Full Text Available This study investigates the cooling performance characteristics of the mobile air-conditioning system using R744 (CO2 for the hybrid electric vehicle as an alternative to both the R-134a and the conventional air-conditioning system. The developed air-conditioning system is operated with an electric driven compressor in the battery driving mode and a belt driven compressor in the engine driving mode. The cooling performance characteristics of the developed system have been analyzed by experiments under various operating conditions of inlet air temperature, air flow rates for the gas cooler side and evaporator side, and electric compressor revolution respectively. As a result, cooling performances of the tested air-conditioning system for the EDC driving mode (electricity driven compressor were better than those for the BDC driving mode (belt driven compressor. The cooling capacity and cooling COP of the tested air-conditioning system for both driving modes were over 5.0 kW and 2.0, respectively. The observed cooling performance of the tested air-conditioning system may be sufficient for the cabin cooling of hybrid electric vehicles.

  15. Cooling Performance Characteristics on Mobile Air-Conditioning System for Hybrid Electric Vehicles

    OpenAIRE

    Ho-Seong Lee; Moo-Yeon Lee

    2013-01-01

    This study investigates the cooling performance characteristics of the mobile air-conditioning system using R744 (CO2) for the hybrid electric vehicle as an alternative to both the R-134a and the conventional air-conditioning system. The developed air-conditioning system is operated with an electric driven compressor in the battery driving mode and a belt driven compressor in the engine driving mode. The cooling performance characteristics of the developed system have been analyzed by experim...

  16. The Effect of Bypass Nozzle Exit Area on Fan Aerodynamic Performance and Noise in a Model Turbofan Simulator

    Science.gov (United States)

    Hughes, Christopher E.; Podboy, Gary, G.; Woodward, Richard P.; Jeracki, Robert, J.

    2013-01-01

    The design of effective new technologies to reduce aircraft propulsion noise is dependent on identifying and understanding the noise sources and noise generation mechanisms in the modern turbofan engine, as well as determining their contribution to the overall aircraft noise signature. Therefore, a comprehensive aeroacoustic wind tunnel test program was conducted called the Fan Broadband Source Diagnostic Test as part of the NASA Quiet Aircraft Technology program. The test was performed in the anechoic NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel using a 1/5 scale model turbofan simulator which represented a current generation, medium pressure ratio, high bypass turbofan aircraft engine. The investigation focused on simulating in model scale only the bypass section of the turbofan engine. The test objectives were to: identify the noise sources within the model and determine their noise level; investigate several component design technologies by determining their impact on the aerodynamic and acoustic performance of the fan stage; and conduct detailed flow diagnostics within the fan flow field to characterize the physics of the noise generation mechanisms in a turbofan model. This report discusses results obtained for one aspect of the Source Diagnostic Test that investigated the effect of the bypass or fan nozzle exit area on the bypass stage aerodynamic performance, specifically the fan and outlet guide vanes or stators, as well as the farfield acoustic noise level. The aerodynamic performance, farfield acoustics, and Laser Doppler Velocimeter flow diagnostic results are presented for the fan and four different fixed-area bypass nozzle configurations. The nozzles simulated fixed engine operating lines and encompassed the fan stage operating envelope from near stall to cruise. One nozzle was selected as a baseline reference, representing the nozzle area which would achieve the design point operating conditions and fan stage performance. The total area change from

  17. Effect of Two Advanced Noise Reduction Technologies on the Aerodynamic Performance of an Ultra High Bypass Ratio Fan

    Science.gov (United States)

    Hughes, Christoper E.; Gazzaniga, John A.

    2013-01-01

    A wind tunnel experiment was conducted in the NASA Glenn Research Center anechoic 9- by 15-Foot Low-Speed Wind Tunnel to investigate two new advanced noise reduction technologies in support of the NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project. The goal of the experiment was to demonstrate the noise reduction potential and effect on fan model performance of the two noise reduction technologies in a scale model Ultra-High Bypass turbofan at simulated takeoff and approach aircraft flight speeds. The two novel noise reduction technologies are called Over-the-Rotor acoustic treatment and Soft Vanes. Both technologies were aimed at modifying the local noise source mechanisms of the fan tip vortex/fan case interaction and the rotor wake-stator interaction. For the Over-the-Rotor acoustic treatment, two noise reduction configurations were investigated. The results showed that the two noise reduction technologies, Over-the-Rotor and Soft Vanes, were able to reduce the noise level of the fan model, but the Over-the-Rotor configurations had a significant negative impact on the fan aerodynamic performance; the loss in fan aerodynamic efficiency was between 2.75 to 8.75 percent, depending on configuration, compared to the conventional solid baseline fan case rubstrip also tested. Performance results with the Soft Vanes showed that there was no measurable change in the corrected fan thrust and a 1.8 percent loss in corrected stator vane thrust, which resulted in a total net thrust loss of approximately 0.5 percent compared with the baseline reference stator vane set.

  18. Analysis of the Solar Radiation Impact on Cooling Performance of the Absorption Chiller

    Science.gov (United States)

    Fedorčák, Pavol; Košičanová, Danica; Nagy, Richard; Mlynár, Peter

    2014-11-01

    Absorption cooling at low power is a new technology which has not yet been applied to current conditioning elements. This paper analyzes the various elements of solar absorption cooling. Individual states were simulated in which working conditions were set for the capability of solar absorption cooling to balance heat loads in the room. The research is based on an experimental device (absorption units with a performance of 10kW) developed at the STU in Bratislava (currently inputs and outputs of cold sources are being measured). Outputs in this paper are processed so that they connect the entire scheme of the solar absorption cooling system (i.e. the relationship between the solar systems hot and cold storage and the absorption unit). To determine the size of the storage required, calculated cooling for summer months is considered by the ramp rate of the absorption unit and required flow rate of the collectors.

  19. Experimental assessment of film cooling performance of short cylindrical holes on a flat surface

    Science.gov (United States)

    Singh, Kuldeep; Premachandran, B.; Ravi, M. R.

    2016-03-01

    The present study is an experimental investigation of film-cooling over a flat surface from the short cylindrical holes. The film cooling holes used in the combustion chamber and the afterburner liner of an aero engine has length-to-diameter (L/D) typically in the range 1-2, while the cooling holes used in turbine blades has L/D > 3. Based on the classification given in the literature, cooling holes with L/D ≤ 3 are named as short holes and cooling holes with L/D > 3 are named as long holes. Short film cooling holes cause jetting of the secondary fluid whereas the secondary fluid emerging from long holes has characteristics similar to fully developed turbulent flow in pipe. In order to understand the difference in the film cooling performance of long and short cooling holes, experimental study is carried out for five values of L/D in the range 1-5, five injection angles, α = 15°-90° and five mainstream Reynolds number 1.25 × 105-6.25 × 105 and two blowing ratios, M = 0.5-1.0. The surface temperature of the test plate is monitored using infrared thermography. The results obtained from the present study showed that the film-cooling effectiveness is higher for the longest holes (L/D = 5) investigated in the present work in comparison to that for the shorter holes. Short holes are found to give better effectiveness at the lowest investigated injection angle i.e. α = 15° in the near cooling hole region, whereas film cooling effectiveness obtained at injection angle, α = 45° is found to be better than other injection angles for longest investigated holes, i.e. L/D = 5.

  20. Evaporative tunnel cooling of dairy cows in the southeast. II: impact on lactation performance.

    Science.gov (United States)

    Smith, T R; Chapa, A; Willard, S; Herndon, C; Williams, R J; Crouch, J; Riley, T; Pogue, D

    2006-10-01

    Heat stress has a dramatic impact on the dairy industry, reducing production and profitability throughout the southeastern United States. In many regions, management techniques can be used to mitigate the effects of heat stress, but available cooling technologies are often overwhelmed by the conditions of chronic heat stress present in southeastern United States. Although combining tunnel ventilation and evaporative cooling (evaporative tunnel cooling) seems to provide superior cooling for dairy cows, there is a dearth of reports on the impact of this technology on milk production. A model evaporative tunnel cooling facility in northern Mississippi was studied using 2 groups of 10 lactating Holstein cows housed in the tunnel barn and 2 groups of 10 matched herdmates housed in an adjacent naturally ventilated free-stall barn. Two 10-wk trials were performed in 2 yr beginning June 25, 2001, and May 26, 2003, in which cows housed outside were cooled by traditional fans and shade alone (2003) or with sprinklers (2001). In both years, the use of evaporative tunnel cooling decreased exposure to conditions of moderate heat stress by 84%. Cows cooled by evaporative tunnel ventilation increased feed intake by 12 and 11% over cows housed outside in 2001 and 2003, respectively. Evaporative tunnel cooling had no effect on milk composition, but increased milk yield over the 10-wk trial by 2.6 +/- 0.27 and 2.8 +/- 0.19 kg/cow per day in 2001 and 2003, respectively. In addition, somatic cell count was decreased 27 to 49% by evaporative tunnel cooling. Thus, under the range of environmental conditions present, evaporative tunnel cooling reliably reduced exposure to conditions of heat stress and improved milk production of lactating dairy cows during the summer season.

  1. Experimental assessment of film cooling performance of short cylindrical holes on a flat surface

    Science.gov (United States)

    Singh, Kuldeep; Premachandran, B.; Ravi, M. R.

    2016-12-01

    The present study is an experimental investigation of film-cooling over a flat surface from the short cylindrical holes. The film cooling holes used in the combustion chamber and the afterburner liner of an aero engine has length-to-diameter (L/D) typically in the range 1-2, while the cooling holes used in turbine blades has L/D > 3. Based on the classification given in the literature, cooling holes with L/D ≤ 3 are named as short holes and cooling holes with L/D > 3 are named as long holes. Short film cooling holes cause jetting of the secondary fluid whereas the secondary fluid emerging from long holes has characteristics similar to fully developed turbulent flow in pipe. In order to understand the difference in the film cooling performance of long and short cooling holes, experimental study is carried out for five values of L/D in the range 1-5, five injection angles, α = 15°-90° and five mainstream Reynolds number 1.25 × 105-6.25 × 105 and two blowing ratios, M = 0.5-1.0. The surface temperature of the test plate is monitored using infrared thermography. The results obtained from the present study showed that the film-cooling effectiveness is higher for the longest holes (L/D = 5) investigated in the present work in comparison to that for the shorter holes. Short holes are found to give better effectiveness at the lowest investigated injection angle i.e. α = 15° in the near cooling hole region, whereas film cooling effectiveness obtained at injection angle, α = 45° is found to be better than other injection angles for longest investigated holes, i.e. L/D = 5.

  2. Performance analysis of a ground-assisted direct evaporative cooling air conditioner

    Energy Technology Data Exchange (ETDEWEB)

    Heidarinejad, Ghassem; Khalajzadeh, Vahid [Department of Mechanical Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran); Delfani, Shahram [Building and Housing Research Center (BHRC), P O Box 13145-1696, Tehran (Iran)

    2010-11-15

    In this paper, the results of performance analysis of a ground-assisted hybrid evaporative cooling system in Tehran have been discussed. A Ground Coupled Circuit (GCC) provides the necessary pre-cooling effects, enabling a Direct Evaporative Cooler (DEC) that cools the air even below its wet-bulb temperature. The GCC includes four vertical ground heat exchangers (GHE) which were arrayed in series configuration. In order to have an accurate prediction of the optimum performance of a GCC, a computational fluid dynamic simulation was performed. Simulation results revealed that the combination of GCC and DEC system could provide comfort condition whereas DEC alone did not. Based on the simulation results the cooling effectiveness of a hybrid system is more than 100%. Thus, this novel hybrid system could decrease the air temperature below the ambient wet-bulb temperature. This environmentally clean and energy efficient system can be considered as an alternative to the mechanical vapor compression systems. (author)

  3. Numerical Examination of the Performance of a Thermoelectric Cooler with Peltier Heating and Cooling

    Science.gov (United States)

    Kim, Chang Nyung; Kim, Jeongho

    2015-10-01

    There has recently been much progress in the development of materials with higher thermoelectric performance, leading to the design of thermoelectric devices for generation of electricity and for heating or cooling. Local heating can be achieved by current flow through an electric resistance, and local heating and cooling can be performed by Peltier heating and cooling. In this study, we developed computer software that can be used to predict the Seebeck and Peltier effects for thermoelectric devices. The temperature, electric potential, heat flow, electric current, and coefficient of performance were determined, with the objective of investigating the Peltier effect in a thermoelectric device. In addition to Peltier heating and cooling, Joule and Thomson heating were quantitatively evaluated for the thermoelectric device.

  4. Cryogenic performance of a conduction-cooling splittable quadrupole magnet for ILC cryomodules

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, N.; Yamamoto, A. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Andreev, N.; Kashikhin, V. S.; Tartaglia, M. A. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Kerby, J. [Argonne National Laboratory, Argonne, 9700 S. Cass Avenue, IL 60439 (United States); Takahashi, M.; Tosaka, T. [Toshiba Corporation Power Systems Company, 2-4 Suehiro-Cho, Tsurumi-Ku, Yokohama, Kanagawa 230-0045 (Japan)

    2014-01-29

    A conduction-cooled splittable superconducting quadrupole magnet was designed and fabricated at Fermilab for use in cryomodules of the International Linear Collider (ILC) type, in which the magnet was to be assembled around the beam tube to avoid contaminating the ultraclean superconducting radio frequency cavity volume. This quadrupole was first tested in a liquid helium bath environment at Fermilab, where its quench and magnetic properties were characterized. Because the device is to be cooled by conduction when installed in cryomodules, a separate test with a conduction-cooled configuration was planned at KEK and Fermilab. The magnet was converted to a conduction-cooled configuration by adding conduction-cooling passages made of high-purity aluminum. Efforts to convert and refabricate the magnet into a cryostat equipped with a double-stage pulse-tube-type cryocooler began in 2011, and a thermal performance test, including a magnet excitation test of up to 30 A, was conducted at KEK. In this test, the magnet with the conduction-cooled configuration was successfully cooled to 4 K within 190 h, with an acceptable heat load of less than 1 W at 4 K. It was also confirmed that the conduction-cooled splittable superconducting quadrupole magnet was practical for use in ILC-type cryomodules.

  5. Cryogenic performance of a conduction-cooling splittable quadrupole magnet for ILC cryomodules

    Science.gov (United States)

    Kimura, N.; Andreev, N.; Kashikhin, V. S.; Kerby, J.; Takahashi, M.; Tartaglia, M. A.; Tosaka, T.; Yamamoto, A.

    2014-01-01

    A conduction-cooled splittable superconducting quadrupole magnet was designed and fabricated at Fermilab for use in cryomodules of the International Linear Collider (ILC) type, in which the magnet was to be assembled around the beam tube to avoid contaminating the ultraclean superconducting radio frequency cavity volume. This quadrupole was first tested in a liquid helium bath environment at Fermilab, where its quench and magnetic properties were characterized. Because the device is to be cooled by conduction when installed in cryomodules, a separate test with a conduction-cooled configuration was planned at KEK and Fermilab. The magnet was converted to a conduction-cooled configuration by adding conduction-cooling passages made of high-purity aluminum. Efforts to convert and refabricate the magnet into a cryostat equipped with a double-stage pulse-tube-type cryocooler began in 2011, and a thermal performance test, including a magnet excitation test of up to 30 A, was conducted at KEK. In this test, the magnet with the conduction-cooled configuration was successfully cooled to 4 K within 190 h, with an acceptable heat load of less than 1 W at 4 K. It was also confirmed that the conduction-cooled splittable superconducting quadrupole magnet was practical for use in ILC-type cryomodules.

  6. The unsteady pressure field and the aerodynamic performances of a Savonius rotor based on the discrete vortex method

    Energy Technology Data Exchange (ETDEWEB)

    Afungchui, David [University of Buea, Faculty of Science, Department of Physics, UB Street, PO Box 63, Molyko, Buea, South West (Cameroon); Kamoun, Baddreddinne; Helali, Ali; Ben Djemaa, Abdellatif [Faculte des Sciences de Sfax, Departement de Physique, Laboratoire de Physique, Appliquee (L.P.A.), Sfax (Tunisia)

    2010-01-15

    The aim of this paper is to numerically explore the non-linear two-dimensional unsteady potential flow over a Savonius rotor and to develop a code for predicting its aerodynamics performances. In the model developed, the rotor is represented in a median plane by two semicircles, displaced along their common diameter. The two semicircles can be considered to produce lifting effects. As a result, they are modelled by a collection of discrete vortices on their contours. The flow field is then governed by the Laplace equation. The versatile Neumann boundary condition, applied over the contour of the semicircles and the Kutta Joukowsky condition applied at the four extremities of the semicircles have been used in the modelling. The torque distribution of the stationary rotor and the unsteady pressure field on the blades of the rotating rotor, predicted by the code developed, have been compared and validated by some experimental data. (author)

  7. Aerodynamic performance enhancement of a flying wing using nanosecond pulsed DBD plasma actuator

    Directory of Open Access Journals (Sweden)

    Han Menghu

    2015-04-01

    Full Text Available Experimental investigation of aerodynamic control on a 35° swept flying wing by means of nanosecond dielectric barrier discharge (NS-DBD plasma was carried out at subsonic flow speed of 20–40 m/s, corresponding to Reynolds number of 3.1 × 105–6.2 × 105. In control condition, the plasma actuator was installed symmetrically on the leading edge of the wing. Lift coefficient, drag coefficient, lift-to-drag ratio and pitching moment coefficient were tested with and without control for a range of angles of attack. The tested results indicate that an increase of 14.5% in maximum lift coefficient, a decrease of 34.2% in drag coefficient, an increase of 22.4% in maximum lift-to-drag ratio and an increase of 2° at stall angle of attack could be achieved compared with the baseline case. The effects of pulsed frequency, amplitude and chord Reynolds number were also investigated. And the results revealed that control efficiency demonstrated strong dependence on pulsed frequency. Moreover, the results of pitching moment coefficient indicated that the breakdown of leading edge vortices could be delayed by plasma actuator at low pulsed frequencies.

  8. Performance analysis on utilization of sky radiation cooling energy for space cooling. Part 2; Hosha reikyaku riyo reibo system ni kansuru kenkyu. 2

    Energy Technology Data Exchange (ETDEWEB)

    Marushima, S.; Saito, T. [Tohoku University, Sendai (Japan)

    1996-10-27

    Studies have been made about a heat accumulation tank type cooling system making use of radiation cooling that is a kind of natural energy. The daily operating cycle of the cooling system is described below. A heat pump air conditioner performs cooling during the daytime and the exhaust heat is stored in a latent heat accumulation tank; the heat is then used for the bath and tapwater in the evening; at night radiation cooling is utilized to remove the heat remnant in the tank for the solidification of the phase change material (PCM); the solidified PCM serves as the cold heat source for the heat pump air conditioner to perform cooling. The new system decelerates urban area warming because it emits the cooler-generated waste heat not into the atmosphere but into space taking advantage of radiation cooling. Again, the cooler-generated waste heat may be utilized for energy saving and power levelling. For the examination of nighttime radiation cooling characteristics, CaCl2-5H2O and Na2HPO4-12H2O were tested as the PCM. Water was used as the heating medium. In the case of a PCM high in latent heat capacity, some work has to be done for insuring sufficient heat exchange for it by, for instance, rendering the flow rate low. The coefficient of performance of the system discussed here is three times higher than that of the air-cooled type heat pump system. 8 refs., 5 figs., 4 tabs.

  9. Optimal control and performance test of solar-assisted cooling system

    KAUST Repository

    Huang, B.J.

    2010-10-01

    The solar-assisted cooling system (SACH) was developed in the present study. The ejector cooling system (ECS) is driven by solar heat and connected in parallel with an inverter-type air conditioner (A/C). The cooling load can be supplied by the ECS when solar energy is available and the input power of the A/C can be reduced. In variable weather, the ECS will probably operate at off-design condition of ejector and the cooling capability of the ECS can be lost completely. In order to make the ejector operate at critical or non-critical double-choking condition to obtain a better performance, an electronic expansion valve was installed in the suction line of the ejector to regulate the opening of the expansion valve to control the evaporator temperature. This will make the SACH always produce cooling effect even at lower solar radiation periods while the ejector performs at off-design conditions. The energy saving of A/C is experimentally shown 50-70% due to the cooling performance of ECS. The long-term performance test results show that the daily energy saving is around 30-70% as compared to the energy consumption of A/C alone (without solar-driven ECS). The total energy saving of A/C is 52% over the entire test period. © 2010 Elsevier Ltd. All rights reserved.

  10. Some Experimental Investigations on Gas Turbine Cooling Performed with Infrared Thermography at Federico II

    Directory of Open Access Journals (Sweden)

    T. Astarita

    2015-01-01

    Full Text Available This paper reviews some experimental measurements of convective heat transfer coefficient distributions which are connected with the cooling of gas turbines, performed by the authors’ research group at the University of Naples Federico II with infrared thermography. Measurements concern impinging jets, cooling of rotating disks, and gas turbine blades, which are either stationary or rotating. The heated thin foil sensor, associated with the detection of surface temperature by means of infrared thermography, is exploited to accurately measure detailed convective heat transfer coefficient maps. The paper also intends to show how to correctly apply the infrared technique in a variety of gas turbines cooling problems.

  11. Effect of floor cooling on farrowing sow and litter performance: Field experiment under Dutch conditions

    OpenAIRE

    Wagenberg, van, A.V.; Peet-Schwering, van der, C.M.C.; Binnendijk, G.P.; Claessen, P.J.P.W.

    2006-01-01

    Lactating sows generally have problems dissipating their body heat to the environment. Cooling the floor under the sow¿s shoulder, called the cool-sow system, is a method to increase body heat removal by conduction, thereby contributing to the thermal comfort of the sow. In this study, the effect of the cool-sow system on the performance of the sow and her piglets in the farrowing room and on the position of the sow in the farrowing crate was determined. In total, 60 sows (parity between 2 an...

  12. Electric Circuit Model for the Aerodynamic Performance Analysis of a Three-Blade Darrieus-Type Vertical Axis Wind Turbine: The Tchakoua Model

    Directory of Open Access Journals (Sweden)

    Pierre Tchakoua

    2016-10-01

    Full Text Available The complex and unsteady aerodynamics of vertical axis wind turbines (VAWTs pose significant challenges for simulation tools. Recently, significant research efforts have focused on the development of new methods for analysing and optimising the aerodynamic performance of VAWTs. This paper presents an electric circuit model for Darrieus-type vertical axis wind turbine (DT-VAWT rotors. The novel Tchakoua model is based on the mechanical description given by the Paraschivoiu double-multiple streamtube model using a mechanical‑electrical analogy. Model simulations were conducted using MATLAB for a three-bladed rotor architecture, characterized by a NACA0012 profile, an average Reynolds number of 40,000 for the blade and a tip speed ratio of 5. The results obtained show strong agreement with findings from both aerodynamic and computational fluid dynamics (CFD models in the literature.

  13. Thermoeconomic impact on combined cycle performance of advanced blade cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Ghigliazza, Francesco; Traverso, Alberto; Massardo, Aristide Fausto [Thermochemical Power Group (TPG), Dipartimento di Macchine, Sistemi Energetici e Trasporti (DIMSET) - University of Genoa (Italy)

    2009-10-15

    In this work the thermoeconomic features of two different combined cycles using air ''open loop'' and steam ''closed loop'' cooled gas turbines are presented and compared in depth. In order to properly estimate both thermodynamic and thermoeconomic performance of the different combined cycles an analytical model of the blade cooling system has been developed in details and outlined in the paper. Internal Thermoeconomic functional analysis is not performed here, as only economic results are shown and discussed. The blade cooling detailed model, originally developed by TPG researchers, has been integrated into the web based modular code WTEMP, already validated for GT based cycles, developed in the last ten years by TPG. It is shown that the closed loop blade cooling configuration has the greatest potential in terms of thermodynamic efficiency and economic competitivity in the mid-term. (author)

  14. Aerodynamic data of space vehicles

    CERN Document Server

    Weiland, Claus

    2014-01-01

    The capacity and quality of the atmospheric flight performance of space flight vehicles is characterized by their aerodynamic data bases. A complete aerodynamic data base would encompass the coefficients of the static longitudinal and lateral motions and the related dynamic coefficients. In this book the aerodynamics of 27 vehicles are considered. Only a few of them did really fly. Therefore the aerodynamic data bases are often not complete, in particular when the projects or programs were more or less abruptly stopped, often due to political decisions. Configurational design studies or the development of demonstrators usually happen with reduced or incomplete aerodynamic data sets. Therefore some data sets base just on the application of one of the following tools: semi-empirical design methods, wind tunnel tests, numerical simulations. In so far a high percentage of the data presented is incomplete and would have to be verified. Flight mechanics needs the aerodynamic coefficients as function of a lot of var...

  15. Study of parameters affecting the performance of solar desiccant cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, A A; Hoo, E A

    1993-01-01

    The performance of a solar desiccant cooling system depends on the performance of its components, particularly the desiccant dehumidifier and solar collectors. The desiccant dehumidifier performance is affected by the properties of the desiccant, particularly the shape of the isotherm and the regeneration temperature. The performance of a solar collector, as one would expect, depends on its operating temperature, which is very close to the desiccant regeneration temperature. The purpose of this study was to identify the desiccant isotherm shape (characterized by separation factor) that would result in the optimum performance - based on thermal coefficient of performance and cooling capacity - of a desiccant cooling cycle operating in ventilation mode. Different regeneration temperatures ranging from 65{degree}C to 160{degree}C were investigated to identify the corresponding optimum isotherm shape at each. Thermal COP dictates the required area of the solar collectors, and the cooling capacity is an indication of the size and cost of the cooling equipment. Staged and no-staged regeneration methods were studied.

  16. Study of parameters affecting the performance of solar desiccant cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, A.A.; Hoo, E.A.

    1993-01-01

    The performance of a solar desiccant cooling system depends on the performance of its components, particularly the desiccant dehumidifier and solar collectors. The desiccant dehumidifier performance is affected by the properties of the desiccant, particularly the shape of the isotherm and the regeneration temperature. The performance of a solar collector, as one would expect, depends on its operating temperature, which is very close to the desiccant regeneration temperature. The purpose of this study was to identify the desiccant isotherm shape (characterized by separation factor) that would result in the optimum performance - based on thermal coefficient of performance and cooling capacity - of a desiccant cooling cycle operating in ventilation mode. Different regeneration temperatures ranging from 65[degree]C to 160[degree]C were investigated to identify the corresponding optimum isotherm shape at each. Thermal COP dictates the required area of the solar collectors, and the cooling capacity is an indication of the size and cost of the cooling equipment. Staged and no-staged regeneration methods were studied.

  17. Development of a prototype thermoelectric space cooling system using phase change material to improve the performance

    Science.gov (United States)

    Zhao, Dongliang

    The thermoelectric cooling system has advantages over conventional vapor compression cooling devices, including compact in size, light in weight, high reliability, no mechanical moving parts, no refrigerant, being powered by direct current, and easily switching between cooling and heating modes. However, it has been long suffering from its relatively high cost and low energy efficiency, which has restricted its usage to niche applications, such as space missions, portable cooling devices, scientific and medical equipment, where coefficient of performance (COP) is not as important as reliability, energy availability, and quiet operation environment. Enhancement of thermoelectric cooling system performance generally relies on two methods: improving thermoelectric material efficiency and through thermoelectric cooling system thermal design. This research has been focused on the latter one. A prototype thermoelectric cooling system integrated with phase change material (PCM) thermal energy storage unit for space cooling has been developed. The PCM thermal storage unit used for cold storage at night, functions as the thermoelectric cooling system's heat sink during daytime's cooling period and provides relatively lower hot side temperature for the thermoelectric cooling system. The experimental test of the prototype system in a reduced-scale chamber has realized an average cooling COP of 0.87, with the maximum value of 1.22. Another comparison test for efficacy of PCM thermal storage unit shows that 35.3% electrical energy has been saved from using PCM for the thermoelectric cooling system. In general, PCM faces difficulty of poor thermal conductivity at both solid and liquid phases. This system implemented a finned inner tube to increase heat transfer during PCM charging (melting) process that directly impacts thermoelectric system's performance. A simulation tool for the entire system has been developed including mathematical models for a single thermoelectric module

  18. Improving of the photovoltaic / thermal system performance using water cooling technique

    Science.gov (United States)

    Hussien, Hashim A.; Numan, Ali H.; Abdulmunem, Abdulmunem R.

    2015-04-01

    This work is devoted to improving the electrical efficiency by reducing the rate of thermal energy of a photovoltaic/thermal system (PV/T).This is achieved by design cooling technique which consists of a heat exchanger and water circulating pipes placed at PV module rear surface to solve the problem of the high heat stored inside the PV cells during the operation. An experimental rig is designed to investigate and evaluate PV module performance with the proposed cooling technique. This cooling technique is the first work in Iraq to dissipate the heat from PV module. The experimental results indicated that due to the heat loss by convection between water and the PV panel's upper surface, an increase of output power is achieved. It was found that without active cooling, the temperature of the PV module was high and solar cells could only achieve a conversion efficiency of about 8%. However, when the PV module was operated under active water cooling condition, the temperature was dropped from 76.8°C without cooling to 70.1°C with active cooling. This temperature dropping led to increase in the electrical efficiency of solar panel to 9.8% at optimum mass flow rate (0.2L/s) and thermal efficiency to (12.3%).

  19. Cooling water system thermal performance analysis using the COCO computer code

    Energy Technology Data Exchange (ETDEWEB)

    Hom, J.; Jakub, R.M.; Durkosh, D.E. [Westinghouse Electric Corp., Pittsburgh, PA (United States). Energy Systems Business Unit

    1996-10-01

    Westinghouse Energy Systems Business Unit (ESBU) has worked with electric utility personnel to analyze the thermal performance of essential cooling water systems at nuclear generating stations. The primary goal of these analyses has been to demonstrate the operability of the cooling water systems during postulated limiting post-accident operation. In previous cooling water system thermal analyses, peak containment operating conditions were generally used as input assuming steady-state conditions. This approach is conservative as it does not take into account the improvement in containment conditions and cooling water system temperatures over time. This approach can, also, lead to an inconsistent set of assumptions between the two distinct analyses which may result in overly conservative calculated system operating conditions. These conditions inevitably impose unnecessary restrictions on cooling water system operation. Over the last few years, Westinghouse ESBU has coupled both the containment integrity and the cooling water system thermal calculations into an integrated analysis. This allows the use of a consistent set of input parameters and assumptions in the calculation of limiting cooling water system operating conditions. This approach has been successfully used to increase system operating margins. This paper provides an overview of this coupled thermal analysis along with examples of where increased operating margins can be applied.

  20. Vortex wake, downwash distribution, aerodynamic performance and wingbeat kinematics in slow-flying pied flycatchers.

    Science.gov (United States)

    Muijres, Florian T; Bowlin, Melissa S; Johansson, L Christoffer; Hedenström, Anders

    2012-02-07

    Many small passerines regularly fly slowly when catching prey, flying in cluttered environments or landing on a perch or nest. While flying slowly, passerines generate most of the flight forces during the downstroke, and have a 'feathered upstroke' during which they make their wing inactive by retracting it close to the body and by spreading the primary wing feathers. How this flight mode relates aerodynamically to the cruising flight and so-called 'normal hovering' as used in hummingbirds is not yet known. Here, we present time-resolved fluid dynamics data in combination with wingbeat kinematics data for three pied flycatchers flying across a range of speeds from near hovering to their calculated minimum power speed. Flycatchers are adapted to low speed flight, which they habitually use when catching insects on the wing. From the wake dynamics data, we constructed average wingbeat wakes and determined the time-resolved flight forces, the time-resolved downwash distributions and the resulting lift-to-drag ratios, span efficiencies and flap efficiencies. During the downstroke, slow-flying flycatchers generate a single-vortex loop wake, which is much more similar to that generated by birds at cruising flight speeds than it is to the double loop vortex wake in hovering hummingbirds. This wake structure results in a relatively high downwash behind the body, which can be explained by the relatively active tail in flycatchers. As a result of this, slow-flying flycatchers have a span efficiency which is similar to that of the birds in cruising flight and which can be assumed to be higher than in hovering hummingbirds. During the upstroke, the wings of slowly flying flycatchers generated no significant forces, but the body-tail configuration added 23 per cent to weight support. This is strikingly similar to the 25 per cent weight support generated by the wing upstroke in hovering hummingbirds. Thus, for slow-flying passerines, the upstroke cannot be regarded as inactive

  1. Performance Studies on Sub-cooling of Cryogenic Liquids Used for Rocket Propulsion Using Helium Bubbling

    Directory of Open Access Journals (Sweden)

    Ramesh T

    2014-03-01

    Full Text Available The sub-cooling of cryogenic propellants contained in tanks is an important and effective method for bringing down the lift-off mass of launch vehicle and thus the performance of the rocket engine is greatly improved. This paper presents the technical and experimental studies conducted on cryogenic liquids such as Liquid Oxygen, Liquid Nitrogen, and Liquid Hydrogen using helium bubbling method. The influence of cooled Helium on the degree of sub-cooling and the variation in flow rate of Helium gas admitted are discussed. The experimental and theoretical studies indicate that the sub-cooling technique using helium injection is a very simple method and can be very well adopted in propellant tanks used for ground and launch vehicle applications.

  2. Influence of the cooling degree upon performances of internal combustion engine

    Science.gov (United States)

    Grǎdinariu, Andrei Cristian; Mihai, Ioan

    2016-12-01

    Up to present, air cooling systems still raise several unsolved problems due to conditions imposed by the environment in terms of temperature and pollution levels. The present paper investigates the impact of the engine cooling degree upon its performances, as important specific power is desired for as low as possible fuel consumption. A technical solution advanced by the authors[1], consists of constructing a bi-flux compressor, which can enhance the engine's performances. The bi-flux axial compressor accomplishes two major functions, that is it cools down the engine and it also turbocharges it. The present paper investigates the temperature changes corresponding to the fresh load, during the use of a bi-flux axial compressor. This compressor is economically simple, compact, and offers an optimal response at low rotational speeds of the engine, when two compression steps are used. The influence of the relative coefficient of air temperature drop upon working agent temperature at the intercooler exit is also investigated in the present work. The variation of the thermal load coefficient by report to the working agent temperature is also investigated during engine cooling. The variation of the average combustion temperature is analyzed in correlation to the thermal load coefficient and the temperatures of the working fluid at its exit from the cooling system. An exergetic analysis was conducted upon the influence of the cooling degree on the motor fluid and the gases resulted from the combustion process.

  3. Performance analysis of nanofluid-cooled microchannel heat sinks

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, T.-H. [Department of Mechanical Engineering, Wufeng Institute of Technology, Chia-Yi 621, Taiwan (China); Chein Reiyu [Department of Mechanical Engineering, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung 402, Taiwan (China)], E-mail: rychein@dragon.nchu.edu.tw

    2007-10-15

    Microchannel heat sink (MCHS) performance using copper-water (Cu-H{sub 2}O) and carbon nanotube-water (CNT-H{sub 2}O) nanofluids as coolants is addressed analytically in this study. The velocity and temperature distributions in the MCHS were obtained by modeling the MCHS as a porous media. The resulting velocity and temperature were then used to evaluate the thermal resistance that characterizes MCHS performance. It was found that the nanofluid reduced the temperature difference between the MCHS bottom wall and bulk nanofluid compared with that from pure fluid. This temperature difference produces a reduction in conductive thermal resistance, which is one of the two sources contributing the total thermal resistance of the MCHS. The other source of thermal resistance, termed as convective thermal resistance, was found to increase when nanofluid is employed as the coolant due to the increase in viscosity and decrease in thermal capacity. Under the condition of a given pressure drop across the MCHS, optimum values of aspect ratio and porosity that producing the minimum thermal resistance can be found. It was found that using nanofluid can enhance the MCHS performance when the porosity and aspect ratio are less than the optimum porosity and aspect ratio. When the porosity and channel aspect ratio are higher than optimum porosity and aspect ratio, the nanofluid did not produce a significant change in MCHS thermal resistance.

  4. Computational fluid dynamics analysis of cyclist aerodynamics: performance of different turbulence-modelling and boundary-layer modelling approaches.

    Science.gov (United States)

    Defraeye, Thijs; Blocken, Bert; Koninckx, Erwin; Hespel, Peter; Carmeliet, Jan

    2010-08-26

    This study aims at assessing the accuracy of computational fluid dynamics (CFD) for applications in sports aerodynamics, for example for drag predictions of swimmers, cyclists or skiers, by evaluating the applied numerical modelling techniques by means of detailed validation experiments. In this study, a wind-tunnel experiment on a scale model of a cyclist (scale 1:2) is presented. Apart from three-component forces and moments, also high-resolution surface pressure measurements on the scale model's surface, i.e. at 115 locations, are performed to provide detailed information on the flow field. These data are used to compare the performance of different turbulence-modelling techniques, such as steady Reynolds-averaged Navier-Stokes (RANS), with several k-epsilon and k-omega turbulence models, and unsteady large-eddy simulation (LES), and also boundary-layer modelling techniques, namely wall functions and low-Reynolds number modelling (LRNM). The commercial CFD code Fluent 6.3 is used for the simulations. The RANS shear-stress transport (SST) k-omega model shows the best overall performance, followed by the more computationally expensive LES. Furthermore, LRNM is clearly preferred over wall functions to model the boundary layer. This study showed that there are more accurate alternatives for evaluating flow around bluff bodies with CFD than the standard k-epsilon model combined with wall functions, which is often used in CFD studies in sports.

  5. Unsteady Aerodynamics of a Savonius wind rotor: a new computational approach for the simulation of energy performance

    Energy Technology Data Exchange (ETDEWEB)

    D' Alessandro, V.; Montelpare, S.; Ricci, R.; Secchiaroli, A. [Universita Politecnica delle Marche, Dipartimento di Energetica, Via Brecce Bianche 1, 60131 Ancona (Italy)

    2010-08-15

    When compared with of other wind turbine the Savonius wind rotor offers lower performance in terms of power coefficient, on the other hand it offers a number of advantages as it is extremely simple to built, it is self-starting and it has no need to be oriented in the wind direction. Although it is well suited to be integrated in urban environment as mini or micro wind turbine it is inappropriate when high power is requested. For this reason several studies have been carried-out in recent years in order to improve its aerodynamic performance. The aim of this research is to gain an insight into the complex flow field developing around a Savonius wind rotor and to evaluate its performance. A mathematical model of the interaction between the flow field and the rotor blades was developed and validated by comparing its results with data obtained at Environmental Wind Tunnel (EWT) laboratory of the ''Polytechnic University of Marche''. (author)

  6. Cooling performance of grid-sheets for highly loaded ultra-supercritical steam turbines

    Institute of Scientific and Technical Information of China (English)

    Dieter BOHN; Robert KREWINKEL; Shuqing TIAN

    2009-01-01

    In order to increase efficiency and achieve a further CO2-reduction, the next generation of power plant turbines will have steam turbine inlet temperatures that are considerably higher than the current ones. The high pressure steam turbine inlet temperature is expected to be increased up to approximately 700℃ with a live steam pressure of 30 MPa. The elevated steam parameters in the high and intermediate pressure turbines can be encountered with Ni-base alloys, but this is a costly alternative associated with many manufacturing difficulties. Colla-borative research centre 561 "Thermally Highly Loaded,Porous and Cooled Multi-Layer Systems for Combined Cycle Power Plants" at RWTH Aachen University proposes cooling the highly loaded turbines instead, as this would necessitate the application of far less Ni-base alloys.To protect the thermally highly loaded components, a sandwich material consisting of two thin face sheets and a core made from a woven wire mesh is used to cover the walls of the steam turbine casing. The cooling steam is led through the woven wire mesh between the two face sheets to achieve a cooling effect. The wire mesh provides the grid-sheet with structural rigidity under varying operating conditions.In the present work, the cooling performance of the grid-sheets will be investigated applying the conjugate heat transfer method to ultra-supercritical live and cooling steam conditions for a section of the cooling structure. The behaviour of the flow and the heat transfer in the grid-sheet will be analyzed in detail using a parameter variation. The numerical results should give a first prediction of the cooling performance under future operating conditions.

  7. Performance analysis of a combined cycle gas turbine power plant by using various inlet air cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Rahim, Murad A. [Department of Mechanical Engineering, Gazi University (Turkey)], e-mail: mrahim@gazi.edu.tr

    2011-07-01

    In recent years, the use of gas turbines in combined cycle power plants has increased. Turbine inlet air cooling appears to be the best solution for maximizing both production and efficiency, particularly in a hot climate. The aim of this study is to determine the impact of different air cooling systems on the gas turbine's performance and carbon dioxide emissions. Computer simulations were carried out, using the THERMOFLEX program, on fogging, evaporative cooling, adsorption cooling, and electrical chiller cooling systems as well as on a base case without cooling system. Results showed that inlet air cooling systems are effective in increasing the efficiency of gas turbine power plants. In addition it was found that absorption chillers are the best system for increasing power generation but that economic and source analyses should be conducted before installing a cooling system. This paper demonstrated that inlet air cooling systems have the ability to increase net power generation of gas turbine power plants.

  8. Influence of the Water-Cooled Heat Exchanger on the Performance of a Pulse Tube Refrigerator

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2017-02-01

    Full Text Available The water-cooled heat exchanger is one of the key components in a pulse tube refrigerator. Its heat exchange effectiveness directly influences the cooling performance of the refrigerator. However, effective heat exchange does not always result in a good performance, because excessively reinforced heat exchange can lead to additional flow loss. In this paper, seven different water-cooled heat exchangers were designed to explore the best configuration for a large-capacity pulse tube refrigerator. Results indicated that the heat exchanger invented by Hu always offered a better performance than that of finned and traditional shell-tube types. For a refrigerator with a working frequency of 50 Hz, the best hydraulic diameter is less than 1 mm.

  9. Flow and Thermal Performance of a Water-Cooled Periodic Transversal Elliptical Microchannel Heat Sink for Chip Cooling.

    Science.gov (United States)

    Wei, Bo; Yang, Mo; Wang, Zhiyun; Xu, Hongtao; Zhang, Yuwen

    2015-04-01

    Flow and thermal performance of transversal elliptical microchannels were investigated as a passive scheme to enhance the heat transfer performance of laminar fluid flow. The periodic transversal elliptical micro-channel is designed and its pressure drop and heat transfer characteristics in laminar flow are numerically investigated. Based on the comparison with a conventional straight micro- channel having rectangular cross section, it is found that periodic transversal elliptical microchannel not only has great potential to reduce pressure drop but also dramatically enhances heat transfer performance. In addition, when the Reynolds number equals to 192, the pressure drop of the transversal elliptical channel is 36.5% lower than that of the straight channel, while the average Nusselt number is 72.8% higher; this indicates that the overall thermal performance of the periodic transversal elliptical microchannel is superior to the conventional straight microchannel. It is suggested that such transversal elliptical microchannel are attractive candidates for cooling future electronic chips effectively with much lower pressure drop.

  10. Large-Eddy Simulation of the Aerodynamic and Aeroacoustic Performance of a Ventilation Fan

    Directory of Open Access Journals (Sweden)

    Stefano Bianchi

    2013-01-01

    Full Text Available There are controversial requirements involved in developing numerical methodologies in order to compute the flow in industrial fans. The full resolution of turbulence spectrum in such high-Reynolds number flow configurations entails unreasonably expensive computational costs. The authors applied the study to a large unidirectional axial flow fan unit for tunnel ventilation to operate in the forward direction under ambient conditions. This delivered cooling air to the tunnel under routine operation, or hot gases at 400∘C under emergency conditions in the event of a tunnel fire. The simulations were carried out using the open source code OpenFOAM, within which they implemented a very large eddy simulation (VLES based on one-equation SGS model to solve a transport equation for the modelled (subgrid turbulent kinetic energy. This subgrid turbulence model improvement is a remedial strategy in VLES of high-Reynolds number industrial flows which are able to tackle the turbulence spectrum’s well-known insufficient resolution. The VLES of the industrial fan permits detecting the unsteady topology of the rotor flow. This paper explores the evolution of secondary flow phenomena and speculates on its influence on the actual load capability when operating at peak-pressure condition. Predicted noise emissions, in terms of sound pressure level spectra, are also compared with experimental results and found to agree within the uncertainty of the measurements.

  11. EXPERIMENTAL RESEARCH ON AERODYNAMIC PERFORMANCE AND EXIT FLOW FIELD OF LOW PRESSURE AXIAL FLOW FAN WITH CIRCUMFERENTIAL SKEWED BLADES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this article, the low pressure axial flow fan with circumferential skewed rotor blade, including the radial blade, the forward-skewed blade and the backward-skewed blade, was studied with experimental methods. The aerodynamic performance of the rotors was measured. At the design condition at outlet of the rotors, detailed flow measurements were performed with a five-hole probe and a Hot-Wire Anemometer (HWA). The results show that compared to the radial rotor, the forward-skewed rotor demonstrates a wider Stable Operating Range (SOR), is able to reduce the total pressure loss in the hub region and make main loading of blade accumulating in the mid-span region. There is a wider wake in the upper mid-span region of the forward-skewed rotor. Compared to the radial rotor, in the backward-skewed rotor there is higher total pressure loss near the hub and shroud regions and lower loss in the mid-span region. In addition, the velocity deficit in the wake is lower at mid-span of the backward-skewed rotor than the forward-skewed rotor.

  12. Simplified approach of predictions of thermal performance for counterflow fully-wet cooling coil

    Science.gov (United States)

    Mansour, M. Khamis; Hassab, M. A.

    2016-11-01

    An innovative correlation associating the effectiveness (ɛ) of the fully-wet cooling coil with its number of transfer unit and vice versa is presented in this work. The thermal performance and design of fully-wet cooling coil can be predicted simply through those correlations. The analytical model was constructed on a basis of solving heat and mass transfer equation "enthalpy potential method" simultaneously coupled with the energy equations. The validity of the new correlations was tested by experimental reported in the available literature. A good agreement with deviation less than 10% was found during the comparison between the output results of the new correlations and those obtained from the literature. The main benefits of those new correlations (1) Its simplicity to be implemented through simple calculations of input parameters (2) It provides helpful guidelines for optimization of wet cooling coil performance during its operation coupling with the thermal system at which the coil is integrated.

  13. Performance of water and diluted ethylene glycol as coolants for electronic cooling

    Directory of Open Access Journals (Sweden)

    M. Gayatri,

    2015-05-01

    Full Text Available As the number of transistors increases with new generation of microprocessor chips, the power draw and heat load to dissipate during operation increases. As a result of increasing the heat loads and heat fluxes the Conventional cooling technologies such as fan, heat sinks are unable to absorb and heat transfer excess heat dissipated by these new microprocessor. So, new technologies are needed to improve the heat removal capacity. In the present work single phase liquid cooling system with mini channel is analyzed and experimentally investigated. Mini channels are chosen as to provide higher heat transfer co-efficient than conventional channel. Copper pipes of 0.36 mm diameter are taken to fabricate heat sink and heat exchanger. A pump is used to circulate the fluid through heat sink and heat exchanger. A solid heated aluminium block to simulate heat generated electronic component is used and electrical input is supplied to the heated aluminium block and cooling system is placed over the heated block. The performance of the cooling system is analyzed from the experimental data obtained. It is experimentally observed that the mini channel liquid cooling system with water as a coolant has better performance than diluted ethylene glycol as coolant at different flow rates. The surface temperature of the heated aluminium block with convective heat transfer co-efficient is observed

  14. Aerodynamically shaped vortex generators

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver; Velte, Clara Marika; Øye, Stig;

    2016-01-01

    An aerodynamically shaped vortex generator has been proposed, manufactured and tested in a wind tunnel. The effect on the overall performance when applied on a thick airfoil is an increased lift to drag ratio compared with standard vortex generators. Copyright © 2015 John Wiley & Sons, Ltd....

  15. Effect of Inlet Clearance on the Aerodynamic Performance of a Centrifugal Blower

    Science.gov (United States)

    Hariharan, C.; Govardhan, M.

    2016-09-01

    The present work reports the effect of inlet clearance on the performance of a centrifugal blower, with parallel wall volute, over its full operating range. For a particular impeller configuration, four volutes based on constant angular momentum principle, have been designed and analysed numerically for varying inlet clearances ranging from 0 mm (ideal clearance) to 5 mm. The computational methodology is validated using experimental data. The results indicate that as the clearance increases, the impeller performance in terms of both static and total pressure rise deteriorate. Further, the stage performances deteriorate in terms of efficiency and specific work for all mass flow rates. However, the performance of volute improves at lower mass flow rates compared to the Best Efficiency Point (BEP). A set of correlations have been developed to predict the change in stage performance as a function of clearance ratio. The non-dimensional values of change in specific work, isentropic efficiency and static pressure are found to be same irrespective of the shape of the volute.

  16. Modeling the cooling performance of vortex tube using a genetic algorithm-based artificial neural network

    Directory of Open Access Journals (Sweden)

    Pouraria Hassan

    2016-01-01

    Full Text Available In this study, artificial neural networks (ANNs have been used to model the effects of four important parameters consist of the ratio of the length to diameter(L/D, the ratio of the cold outlet diameter to the tube diameter(d/D, inlet pressure(P, and cold mass fraction (Y on the cooling performance of counter flow vortex tube. In this approach, experimental data have been used to train and validate the neural network model with MATLAB software. Also, genetic algorithm (GA has been used to find the optimal network architecture. In this model, temperature drop at the cold outlet has been considered as the cooling performance of the vortex tube. Based on experimental data, cooling performance of the vortex tube has been predicted by four inlet parameters (L/D, d/D, P, Y. The results of this study indicate that the genetic algorithm-based artificial neural network model is capable of predicting the cooling performance of vortex tube in a wide operating range and with satisfactory precision.

  17. An Engine Research Program Focused on Low Pressure Turbine Aerodynamic Performance

    Science.gov (United States)

    Castner, Raymond; Wyzykowski, John; Chiapetta, Santo; Adamczyk, John

    2002-01-01

    A comprehensive test program was performed in the Propulsion Systems Laboratory at the NASA Glenn Research Center, Cleveland Ohio using a highly instrumented Pratt and Whitney Canada PW 545 turbofan engine. A key objective of this program was the development of a high-altitude database on small, high-bypass ratio engine performance and operability. In particular, the program documents the impact of altitude (Reynolds Number) on the aero-performance of the low-pressure turbine (fan turbine). A second objective was to assess the ability of a state-of-the-art CFD code to predict the effect of Reynolds number on the efficiency of the low-pressure turbine. CFD simulation performed prior and after the engine tests will be presented and discussed. Key findings are the ability of a state-of-the art CFD code to accurately predict the impact of Reynolds Number on the efficiency and flow capacity of the low-pressure turbine. In addition the CFD simulations showed the turbulent intensity exiting the low-pressure turbine to be high (9%). The level is consistent with measurements taken within an engine.

  18. Laboratory Performance Of Evaporative Cooler Using Jute Fiber Ropes As Cooling Media

    OpenAIRE

    Kulkarni, R K; S.P.S. Rajput

    2014-01-01

    Evaporative coolers use a variety of cooling media like wood wool, cellulose, aspen. This paper analyses the performance of jute fiber ropes as alternative cooling media. They are capable of retaining high moisture and have a large wetted surface area. Hot and dry air is allowed to flow over the wet jute rope bank tightly held between two plates which are integral part of two tanks. The inlet conditions of air varied from 30.5 0C dry bulb temperature and 52 % relative humidity to ...

  19. Aerodynamics of Race Cars

    Science.gov (United States)

    Katz, Joseph

    2006-01-01

    Race car performance depends on elements such as the engine, tires, suspension, road, aerodynamics, and of course the driver. In recent years, however, vehicle aerodynamics gained increased attention, mainly due to the utilization of the negative lift (downforce) principle, yielding several important performance improvements. This review briefly explains the significance of the aerodynamic downforce and how it improves race car performance. After this short introduction various methods to generate downforce such as inverted wings, diffusers, and vortex generators are discussed. Due to the complex geometry of these vehicles, the aerodynamic interaction between the various body components is significant, resulting in vortex flows and lifting surface shapes unlike traditional airplane wings. Typical design tools such as wind tunnel testing, computational fluid dynamics, and track testing, and their relevance to race car development, are discussed as well. In spite of the tremendous progress of these design tools (due to better instrumentation, communication, and computational power), the fluid dynamic phenomenon is still highly nonlinear, and predicting the effect of a particular modification is not always trouble free. Several examples covering a wide range of vehicle shapes (e.g., from stock cars to open-wheel race cars) are presented to demonstrate this nonlinear nature of the flow field.

  20. Iterative learning control applied to a non-linear vortex panel model for improved aerodynamic load performance of wind turbines with smart rotors

    Science.gov (United States)

    Blackwell, Mark W.; Tutty, Owen R.; Rogers, Eric; Sandberg, Richard D.

    2016-01-01

    The inclusion of smart devices in wind turbine rotor blades could, in conjunction with collective and individual pitch control, improve the aerodynamic performance of the rotors. This is currently an active area of research with the primary objective of reducing the fatigue loads but mitigating the effects of extreme loads is also of interest. The aerodynamic loads on a wind turbine blade contain periodic and non-periodic components and one approach is to consider the application of iterative learning control algorithms. In this paper, the control design is based on a simple, in relative terms, computational fluid dynamics model that uses non-linear wake effects to represent flow past an airfoil. A representation for the actuator dynamics is included to undertake a detailed investigation into the level of control possible and on how performance can be effectively measured.

  1. The aerodynamic effects of wheelspace coolant injection into the mainstream flow of a high pressure gas turbine

    Science.gov (United States)

    McLean, Christopher Elliot

    Modern gas turbine engines operate with mainstream gas temperatures exceeding 1450°C in the high-pressure turbine stage. Unlike turbine blades, rotor disks and other internal components are not designed to withstand the extreme temperatures found in mainstream flow. In modern gas turbines, cooling air is pumped into the wheelspace cavities to prevent mainstream gas ingestion and then exits through a seal between the rotor and the nozzle guide vane (NGV) thereby mixing with the mainstream flow. The primary purpose for the wheelspace cooling air is the cooling of the turbine wheelspace. However, secondary effects arise from the mixing of the spent cooling air with the mainstream flow. The exiting cooling air is mixed with the hot mainstream flow effecting the aerodynamic and performance characteristics of the turbine stage. The physics underlying this mixing process and its effects on stage performance are not yet fully understood. The relative aerodynamic and performance effects associated with rotor - NGV gap coolant injections were investigated in the Axial Flow Turbine Research Facility (AFTRF) of the Center for Gas Turbines and Power of The Pennsylvania State University. This study quantifies the secondary effects of the coolant injection on the aerodynamic and performance character of the turbines main stream flow for root injection, radial cooling, and impingement cooling. Measurement and analysis of the cooling effects were performed in both stationary and rotational frames of reference. The AFTRF is unique in its ability to perform long duration cooling measurements in the stationary and rotating frames. The effects of wheelspace coolant mixing with the mainstream flow on total-to-total efficiency, energy transport, three dimensional velocity field, and loading coefficient were investigated. Overall, it was found that a small quantity (1%) of cooling air can have significant effects on the performance character and exit conditions of the high pressure stage

  2. Initial Low-Reynolds Number Iced Aerodynamic Performance for CRM Wing

    Science.gov (United States)

    Woodard, Brian; Diebold, Jeff; Broeren, Andy; Potapczuk, Mark; Lee, Sam; Bragg, Michael

    2015-01-01

    NASA, FAA, ONERA, and other partner organizations have embarked on a significant, collaborative research effort to address the technical challenges associated with icing on large scale, three-dimensional swept wings. These are extremely complex phenomena important to the design, certification and safe operation of small and large transport aircraft. There is increasing demand to balance trade-offs in aircraft efficiency, cost and noise that tend to compete directly with allowable performance degradations over an increasing range of icing conditions. Computational fluid dynamics codes have reached a level of maturity that they are being proposed by manufacturers for use in certification of aircraft for flight in icing. However, sufficient high-quality data to evaluate their performance on iced swept wings are not currently available in the public domain and significant knowledge gaps remain.

  3. Parametric Study and Optimization of Ceiling Fan Blades for Improved Aerodynamic Performance

    Directory of Open Access Journals (Sweden)

    Ehsan Adeeb

    2016-01-01

    Full Text Available This paper includes parametric study and optimization of non-linear ceiling fan blades by combining the techniques of Design of Experiments (DOE, Response Surface Methods (RSM and Computational Fluid Dynamics (CFD. Specifically, the nonlinear (elliptical planform shape of ceiling fan blade is investigated in conjunction with blade tip width, root and tip angle of attack. Sixteen cases are designed for three blade ceiling fan using two level full factorial model. The flow field is modeled using Reynolds-Averaged-Navier-Stokes approach. The performance variables used to formulate a multi-objective optimization problem are volumetric flow rate, torque and energy efficiency. Response Surface Method is used to generate the optimized design for non-linear ceiling fan blade profile. The results reveal that the interactions between the design variables play a significant role in determining the performance. It is concluded that the nonlinear forward sweep has a moderate effect on response parameters.

  4. Performance Assessment of 239 Series Sub-cooling Heat Exchangers for the Large Hadron Collider

    CERN Document Server

    Riddone, G; Roussel, P; Moracchioli, R; Tavian, L

    2006-01-01

    Helium sub-cooling heat exchangers of the counter-flow type are used to minimize the vapor fraction produced in the final expansion of the 1.9 K distributed cooling loops used for cooling the superconducting magnets of the Large Hadron Collider (LHC). These components are of compact design, featuring low-pressure drop and handling very low pressure vapor at low temperature. Following a qualification phase of prototypes, a contract has been placed in European industry for the supply of 239 heat exchanger units. Different levels of extracted heat load require three different variants of heat exchangers. This paper will describe the manufacturing phase with emphasis on the main difficulties encountered to keep the production quality after a brief recall of the prototype phase. Finally, the acceptance tests performed at room temperature and at the nominal cryogenic condition at the factory and at CEA-Grenoble will be presented.

  5. Laboratory Performance Of Evaporative Cooler Using Jute Fiber Ropes As Cooling Media

    Directory of Open Access Journals (Sweden)

    R.K.Kulkarni

    2014-12-01

    Full Text Available Evaporative coolers use a variety of cooling media like wood wool, cellulose, aspen. This paper analyses the performance of jute fiber ropes as alternative cooling media. They are capable of retaining high moisture and have a large wetted surface area. Hot and dry air is allowed to flow over the wet jute rope bank tightly held between two plates which are integral part of two tanks. The inlet conditions of air varied from 30.5 0C dry bulb temperature and 52 % relative humidity to 34.5 0C dry bulb temperature and 32 % relative humidity. Outlet temperature of air is measured and saturation efficiency and cooling capacity are calculated. The outlet dry bulb temperature is obtained between 25.8 0C and 26.2 0C.The saturation efficiencies range from 69 % to 59 % and the cooling capacity is obtained between 6173 kJ/h and 11979 kJ/h. Thus jute fiber ropes prove to be a good alternative cooling media in evaporative cooler

  6. The Effect of the Phase Angle between the Forewing and Hindwing on the Aerodynamic Performance of a Dragonfly-Type Ornithopter

    OpenAIRE

    2016-01-01

    Dragonflies achieve agile maneuverability by flapping four wings independently. Different phase angles between the flapping forewing and hindwing have been observed during various flight modes. The aerodynamic performance depends on phase angle control, as exemplified by an artificial flying ornithopter. Here, we present a dragonfly-like ornithopter whose phase angle was designed to vary according to the phase lag between the slider-cranks of the forewing and hindwing. Two microelectromechani...

  7. Performance evaluation of three different types of local evaporative cooling pads in greenhouses in Sudan

    OpenAIRE

    Ahmed, Egbal Mohammed; Abaas, Osama; Ahmed, Mohammed; Ismail, Mohd Rodzi

    2010-01-01

    This study was conducted in Date Palm Technology Company Limited, Shambat, Khartoum State. To evaluate performance of three types of evaporative cooling pads for greenhouses (celdek pads, straw pads and sliced wood pads), as compared to the conditions outside the greenhouses (control), for pads. Performance evaluation includes environmental parameters (temperature and relative humidity at 8 am, 1 pm and 6 pm) and crop parameters (length and stem diameter, leaves number and width, fruit length...

  8. Research on design methods and aerodynamics performance of CQUDTU-B21 airfoil

    DEFF Research Database (Denmark)

    Chen, Jin; Cheng, Jiangtao; Wen, Zhong Shen

    2012-01-01

    This paper presents the design methods of CQU-DTU-B21 airfoil for wind turbine. Compared with the traditional method of inverse design, the new method is described directly by a compound objective function to balance several conflicting requirements for design wind turbine airfoils, which based...... on design theory of airfoil profiles, blade element momentum (BEM) theory and airfoil Self-Noise prediction model. And then an optimization model with the target of maximum power performance on a 2D airfoil and low noise emission of design ranges for angle of attack has been developed for designing CQU...

  9. NASP aerodynamics

    Science.gov (United States)

    Whitehead, Allen H., Jr.

    1989-01-01

    This paper discusses the critical aerodynamic technologies needed to support the development of a class of aircraft represented by the National Aero-Space Plane (NASP). The air-breathing, single-stage-to-orbit mission presents a severe challenge to all of the aeronautical disciplines and demands an extension of the state-of-the-art in each technology area. While the largest risk areas are probably advanced materials and the development of the scramjet engine, there remains a host of design issues and technology problems in aerodynamics, aerothermodynamics, and propulsion integration. The paper presents an overview of the most significant propulsion integration problems, and defines the most critical fluid flow phenomena that must be evaluated, defined, and predicted for the class of aircraft represented by the Aero-Space Plane.

  10. Development and Performance of an Advanced Ejector Cooling System for a Sustainable Built Environment

    Directory of Open Access Journals (Sweden)

    Paulo ePereira

    2015-06-01

    Full Text Available Ejector refrigeration is a promising technology for the integration into solar driven cooling systems because of its relative simplicity and low initial cost. The major drawback of such a system is associated to its relatively low coefficient of performance (COP under variable operating conditions. In order to overcome this problem, an advanced ejector was developed that changes its geometrical features depending on the upstream and downstream conditions. This paper provides a short overview of the development process and results of a small cooling capacity (1.5 kW solar driven cooling system using a variable geometry ejector. During the design steps, a number of theoretical works have been carried out, including the selection of the working fluid, the determination of the geometrical requirements and prototype design. Based on the analysis, R600a was selected as working fluid. A prototype was constructed with two independent variable geometrical factors: the area ratio and the nozzle exit position. A test rig was also assembled in order to test the ejector performance under controlled laboratory conditions and to elaborate a control algorithm for the variable geometry. Ejector performance was assessed by calculation of cooling cycle COP, entrainment ratio and critical back pressure. The results show that for a condenser pressure of 3 bar, an 80% increase in the COP was obtained when compared to the performance of a fixed geometry ejector. Experimental COP values varied between 0.4 and 0.8, depending on operating conditions. Currently the cooling cycle is being integrated into a solar driven demonstration site for long term in situ assessment.

  11. Missile Aerodynamics

    Science.gov (United States)

    1979-02-01

    Me 2 L~e coefficient de frottement CI est gnralement n~glig6. L’approximation est justifige par le fait que, qf , nul au recollement, est partout...be costly in terms of time and money. One should aim for a situation where an error of, say, 10% in estimating an aerodynamic coefficient or...constructing tables of forces and moments, or their coefficients , as functions of variables such as inci- dence angle, roll angle, speed and altitude, and

  12. An artificial neural network approach for aerodynamic performance retention in airframe noise reduction design of a 3D swept wing model

    Directory of Open Access Journals (Sweden)

    Tao Jun

    2016-10-01

    Full Text Available With the progress of high-bypass turbofan and the innovation of silencing nacelle in engine noise reduction, airframe noise has now become another important sound source besides the engine noise. Thus, reducing airframe noise makes a great contribution to the overall noise reduction of a civil aircraft. However, reducing airframe noise often leads to aerodynamic performance loss in the meantime. In this case, an approach based on artificial neural network is introduced. An established database serves as a basis and the training sample of a back propagation (BP artificial neural network, which uses confidence coefficient reasoning method for optimization later on. Then the most satisfactory configuration is selected for validating computations through the trained BP network. On the basis of the artificial neural network approach, an optimization process of slat cove filler (SCF for high lift devices (HLD on the Trap Wing is presented. Aerodynamic performance of both the baseline and optimized configurations is investigated through unsteady detached eddy simulations (DES, and a hybrid method, which combines unsteady DES method with acoustic analogy theory, is employed to validate the noise reduction effect. The numerical results indicate not merely a significant airframe noise reduction effect but also excellent aerodynamic performance retention simultaneously.

  13. An artificial neural network approach for aerodynamic performance retention in airframe noise reduction design of a 3D swept wing model

    Institute of Scientific and Technical Information of China (English)

    Tao Jun; Sun Gang

    2016-01-01

    With the progress of high-bypass turbofan and the innovation of silencing nacelle in engine noise reduction, airframe noise has now become another important sound source besides the engine noise. Thus, reducing airframe noise makes a great contribution to the overall noise reduction of a civil aircraft. However, reducing airframe noise often leads to aerodynamic perfor-mance loss in the meantime. In this case, an approach based on artificial neural network is intro-duced. An established database serves as a basis and the training sample of a back propagation (BP) artificial neural network, which uses confidence coefficient reasoning method for optimization later on. Then the most satisfactory configuration is selected for validating computations through the trained BP network. On the basis of the artificial neural network approach, an optimization pro-cess of slat cove filler (SCF) for high lift devices (HLD) on the Trap Wing is presented. Aerody-namic performance of both the baseline and optimized configurations is investigated through unsteady detached eddy simulations (DES), and a hybrid method, which combines unsteady DES method with acoustic analogy theory, is employed to validate the noise reduction effect. The numerical results indicate not merely a significant airframe noise reduction effect but also excel-lent aerodynamic performance retention simultaneously.

  14. The aerodynamic performance of several flow control devices for internal flow systems

    Science.gov (United States)

    Eckert, W. T.; Wettlaufer, B. M.; Mort, K. W.

    1982-01-01

    An experimental reseach and development program was undertaken to develop and document new flow-control devices for use in the major modifications to the 40 by 80 Foot wind tunnel at Ames Research Center. These devices, which are applicable to other facilities as well, included grid-type and quasi-two-dimensional flow straighteners, louver panels for valving, and turning-vane cascades with net turning angles from 0 deg to 90 deg. The tests were conducted at model scale over a Reynolds number range from 2 x 100,000 to 17 x 100,000, based on chord. The results showed quantitatively the performance benefits of faired, low-blockage, smooth-surface straightener systems, and the advantages of curved turning-vanes with hinge-line gaps sealed and a preferred chord-to-gap ratio between 2.5 and 3.0 for 45 deg or 90 deg turns.

  15. The effect of shielding on the aerodynamic performance of Savonius wind turbines

    Science.gov (United States)

    Morcos, S. M.; Khalafallah, M. G.; Heikel, H. A.

    The effect of the flat plate shield on the performance of two-bladed Savonius rotor has been experimentally determined. Tests were carried out in a low speed wind tunnel with a working section of 1.0 sq m. Flat plate shields with various values of plate width and inclination angle were tested in order to determine the optimum configuration. The maximum power coefficient of the Savonius rotor was increased from 0.22 for the case without shielding to 0.34 for the case with an optimum shielding configuration. The addition of a flat plate shield to the Savonius rotor can, therefore, enhance the power coefficient to values approaching the more elaborate wind turbines without affecting the simplicity of the Savonius rotor.

  16. Transient Analysis and Performance Prediction of Nocturnal Radiative Cooling of a Building in Owerri, Nigeria

    Directory of Open Access Journals (Sweden)

    K.N. Nwaigwe

    2012-08-01

    Full Text Available A study aimed at a Transient analysis and performance prediction of passive cooling of a building using long wave nocturnal radiation in Owerri, Nigeria are presented. The system modeled consists of the room of a building with a radiator panel attached to its roof, water storage tank located inside the room, pump to circulate water through the radiator panel at night and through a heat exchanger in the room during the day. The mathematical model is based on the thermal radiation properties of the local atmosphere, the heat exchange equations of the radiator panel with the sky during the night and the equations incorporating the relevant heat transfers within the space to be cooled during the day. The resulting equations were transformed into explicit finite difference forms for easy implementation on a personal computer in MATLAB language. This numerical model permits the evaluation of the rate of heat removal from the water storage tank through the radiator panel surface area, Qwt,out, temperature depression between the ambient and room temperatures (Tamb-Trm and total heat gained by water in the storage tank from the space to be cooled through the action of the convector during the day, Qwt,in. The resulting rate of heat removal from the radiator gave a value of 57.6 W/m2, temperature depression was predicted to within 1-1.5ºC and the rate of heat gain by the storage water was 60 W/m2. A sensitivity analysis of the system parameters to ±25% of the base case input values was carried out and the results given as a percentage variation of the above system performance parameters showed consistency to the base case results. An optimal scheme for the modeled 3.0×3.0×2.5 m3 room showed a radiator area of 18.2 m2, a convector area of 28.62 m2 and a tank volume of 1.57 m3. These results show that passive nocturnal cooling technique is a promising solution to the cooling needs for preservation of food and other agricultural produce. It is also

  17. Cooling Performance Evaluation of the Hybrid Heat Pipe for Spent Nuclear Fuel Dry Storage Cask

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Yeong Shin; Bang, In Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    To evaluate the concept of the cooling device, 2-step CFD analysis was conducted for the cooling performance of hybrid heat pipe, which consists of single fuel assembly model and full scope dry cask model. As a passive cooling device of the metal cask for dry storage of spent nuclear fuel, hybrid heat pipe was applied to DPC developed in Korea. Hybrid heat pipe is the heat pipe containing neutron absorber can be used as a passive cooling in nuclear application with both decay heat removal and control the reactivity. In this study, 2-step CFD analysis was performed to find to evaluate the heat pipe-based passive cooling system for the application to the dry cask. Only spent fuel pool cannot satisfy the demands for high burnup fuel and large amount of spent fuel. Therefore, it is necessary to prepare supplement of the storage facilities. As one of the candidate of another type of storage, dry storage method have been preferred due to its good expansibility of storage capacity and easy long-term management. Dry storage uses the gas or air as coolant with passive cooling and neutron shielding materials was used instead of water in wet storage system. It is relatively safe and emits little radioactive waste for the storage. As short term actions for the limited storage capacity of spent fuel pool, it is considered to use dry interim/long term storage method to increase the capacity of spent nuclear fuel storage facilities. For 10-year cooled down spent fuel in the pool storage, fuel rod temperature inside metal cask is expected over 250 .deg. C in simulation. Although it satisfied the criteria that cladding temperature of the spent fuel should keep under 400 .deg. C during storage period, high temperature inside cask can accelerate the thermal degradation of the structural materials consisting metal cask and fuel assembly as well as limitation of the storage capacity of metal cask. In this paper, heat pipe-based cooling device for the dry storage cask was suggested for

  18. Experiments of effects of inlet-air distortion on aerodynamic performance in transonic compressor

    Institute of Scientific and Technical Information of China (English)

    LI Mao-yi; YUAN Wei; LU Ya-jun; SONG Xi-zhen; LU Li-peng

    2013-01-01

    The inlet-air distortion which was caused by high angle-of-attack flight was simulated by plugboard.Experiments were conducted on a transonic axial-flow compressor's rotor at 98% rotating speed.The flow field characteristics and mechanism of performance degradation were analyzed in detail.The compressor inlet was divided into four sectors at circumference under inlet-air distortion.They were undistorted sector,transition sector A where the rotor was rotating into the distortion sector,distorted sector and transition sector B where the rotor was rotating out of the distortion sector.The experimental results show that compared with undistorted sector,there is a subsonic flow in transition sector A,so the pressure ratio is decreased by a large margin in this sector.However,the shock wave is enhanced in distortion sector and transition sector B,and thus the pressure ratio increases in these sectors.Because of the different works at circumference,the phase angle of total pressure changes 90° when the inlet total pressure distortion passes through compressor rotor.In addition,the frequency and amplitude of disturbances in front of the rotor strengthenes under inlet distortion,so the unstable flow would take place in advance.In addition,the position of stall inception is in one of the transition sectors.

  19. Effects of pre-cooling procedures on intermittent-sprint exercise performance in warm conditions.

    Science.gov (United States)

    Duffield, Rob; Marino, Frank E

    2007-08-01

    The aim of this study was to determine whether pre-cooling procedures improve both maximal sprint and sub-maximal work during intermittent-sprint exercise. Nine male rugby players performed a familiarisation session and three testing sessions of a 2 x 30-min intermittent sprint protocol, which consisted of a 15-m sprint every min separated by free-paced hard-running, jogging and walking in 32 degrees C and 30% humidity. The three sessions included a control condition, Ice-vest condition and Ice-bath/Ice-vest condition, with respective cooling interventions imposed for 15-min pre-exercise and 10-min at half-time. Performance measures of sprint time and % decline and distance covered during sub-maximal exercise were recorded, while physiological measures of core temperature (T (core)), mean skin temperature (T (skin)), heart rate, heat storage, nude mass, rate of perceived exertion, rate of thermal comfort and capillary blood measures of lactate [La(-)], pH, Sodium (Na(+)) and Potassium (K(+)) were recorded. Results for exercise performance indicated no significant differences between conditions for the time or % decline in 15-m sprint efforts or the distance covered during sub-maximal work bouts; however, large effect size data indicated a greater distance covered during hard running following Ice-bath cooling. Further, lowered T (core), T (skin), heart rate, sweat loss and thermal comfort following Ice-bath cooling than Ice-vest or Control conditions were present, with no differences present in capillary blood measures of [La(-)], pH, K(+) or Na(+). As such, the ergogenic benefits of effective pre-cooling procedures in warm conditions for team-sports may be predominantly evident during sub-maximal bouts of exercise.

  20. Passive solar/Earth sheltered office/dormitory cooling season thermal performance

    Science.gov (United States)

    Christian, J.

    1984-06-01

    Continuous detailed hourly thermal performance measurements were taken since February 1982 in and around an occupied, underground, 4000 ft(2) office/dormitory building at the Oak Ridge National Laboratory in Oak Ridge, Tennessee. This building has a number of energy saving features which were analyzed relative to their performance in a southeastern US climate and with respect to overall commercial building performance. Cooling season performance is documented, as well as effects of earth constact, interior thermal mass, an economizer cycle and interface of an efficient building envelope with a central three-ton heat pump. The Joint Institute Dormitory obtains a cooling energy savings of about 30% compared with an energy-efficient, above-grade structure and has the potential to save as much as 50%. The proper instllation of the overhand, interior thermal mass, massive supply duct system, and earth contact team up to prevent summertime overheating. From May through September, this building cost a total of $300 (at 5.7) cents/kWh) to cool and ventilate 24 hours per day. Besides thermal performance of the building envelope, extensive comfort data was taken illustrating that at least 90% of the occupants are comfortable all of the time according to the PMV measurements.

  1. Simulation and Experiment Research of Aerodynamic Performance of Small Axial Fans with Struts

    Institute of Scientific and Technical Information of China (English)

    CHU Wei; LIN Peifeng; ZHANG Li; JIN Yingzi; WANG Yanping; Heuy Dong Kim; Toshiaki Setoguchi

    2016-01-01

    Interaction between rotor and struts has great effect on the performance of small axial fan systems.The small axial fan systems are selected as the studied objects in this paper,and four square struts are downstream of the rotor.The cross section of the struts is changed to the cylindrical shapes for the investigation:one is in the same hydranlic diameter as the square struts and another one is in the same cross section as the square struts.Influence of the shape of the struts on the static pressure characteristics,the internal flow and the sound emission of the small axial fans are studied.Standard K-ε turbulence model and SIMPLE algorithm are applied in the calculation of the steady fluid field,and the curves of the pressure rising against the flow rate are obtained,which demonstrates that the simulation results are in nice consistence with the experimental data.The steady calculation results are set as the initial field in the unsteady calculation.Large eddy simulation and PISO algorithm are used in the transient calculation,and the Ffowcs Wtlliams-Hawkings model is introduced to predict the sound level at the eight monitoring points.The research results show that:the static pressure coefficients of the fan with cylindrical struts increase by about 25% compared to the fan with square struts,and the efficiencies increase by about 28.6%.The research provides a theoretical guide for shape optimization and noise reduction of small axial fan with struts.

  2. Acoustic and aerodynamic performance of a 1.83 meter (6 foot) diameter 1.2 pressure ratio fan (QF-6). [for short takeoff aircraft

    Science.gov (United States)

    Woodward, R. P.; Lucas, J. G.; Stakolich, E. G.

    1974-01-01

    A 1.2-pressure-ratio, 1.83-meter-(6-ft-) diameter experimental fan stage with characteristics suitable for use in STOL aircraft engines was tested for acoustic and aerodynamic performance. The design incorporated features for low noise, including absence of inlet guide vanes, low rotor-blade-tip speed, low aerodynamic blade loading, and long axial spacing between the rotor and stator rows. The stage was run with four nozzles of different area. The perceived noise along a 152.4 meter (500-ft) sideline was rear-quadrant dominated with a maximum design-point level of 103.9 PNdb. The acoustic 1/3-octave results were analytically separated into broadband and pure-tone components. It was found that the stage noise levels generally increase with a decrease in nozzle area, with this increase observed primarily in the broadband noise component. A stall condition was documented acoustically with a 90-percent-of-design-area nozzle.

  3. Acoustic and aerodynamic performance of a 1.83-meter (6-ft) diameter 1.25-pressure-ratio fan (QF-8)

    Science.gov (United States)

    Woodward, R. P.; Lucas, J. G.

    1976-01-01

    A 1.25-pressure-ratio 1.83-meter (6-ft) tip diameter experimental fan stage with characteristics suitable for engine application on STOL aircraft was tested for acoustic and aerodynamic performance. The design incorporated proven features for low noise, including absence of inlet guide vanes, low rotor blade tip speed, low aerodynamic blade loading, and long axial spacing between the rotor and stator blade rows. The fan was operated with five exhaust nozzle areas. The stage noise levels generally increased with a decrease in nozzle area. Separation of the acoustic one-third octave results into broadband and pure-tone components showed the broadband noise to be greater than the corresponding pure-tone components. The sideline perceived noise was highest in the rear quadrants. The acoustic results of QF-8 were compared with those of two similar STOL application fans in the test series. The QF-8 had somewhat higher relative noise levels than those of the other two fans. The aerodynamic results of QF-8 and the other two fans were compared with corresponding results from 50.8-cm (20-in.) diam scale models of these fans and design values. Although the results for the full-scale and scale models of the other two fans were in reasonable agreement for each design, the full-scale fan QF-8 results showed poor performance compared with corresponding model results and design expectations. Facility effects of the full-scale fan QF-8 installation were considered in analyzing this discrepancy.

  4. Study on Cooling Performance of Stirling Cycle Machine wiht New Regenerator Matrix

    Science.gov (United States)

    Kagawa, Noboru; Kitahama, Dai; Takeuchi, Takuro; Matsuguchi, Atsushi; Tsuruno, Seizo

    In order to develop Stirling cycle machines with high efficiency, suitable regenerator for each machine must be designed. To realize the flexibility of design and to improve the performance of regenerator, a new matrix, mesh sheet was proposed. It is a plate type with electrically etched holes. Each small hole is connected with neighboring holes by grooves on the plate. The performance test of cooling mode was carried out with a 3-kW Stirling engine in order to measure its cooling performance. Three types of the mesh sheet were developed and two of them were respectively stacked to install in the machine. Also, the pressure and regenerator losses were compared with conventional stacked wire gauzes and the mesh sheets. From the results, it was clarified that the performance of the cooling mode was improved about 5 to 40 % by the mesh sheet. In this paper, the relation between the dimensions of the mesh sheet, the pressure and regenerator losses were also clarified.

  5. Experimental study of operation performance of a low power thermoelectric cooling dehumidifier

    Directory of Open Access Journals (Sweden)

    Wang Huajun, Qi Chengying

    2010-05-01

    Full Text Available The present work was performed to apply thermoelectric technology to a low power dehumidifying device as an alternative to the conventional vapor-compression refrigeration systems. The experimental prototype of a small-scale thermoelectric dehumidifier (TED with rectangular cooling fins was built and its operation performance was studied experimentally. The results showed that the TED experienced two typical thermodynamic processes including the cooling dehumidification and the isothermal dehumidification, where the latter was dominated. It was found that there existed a peak during the variation of the average coefficient of performance (COP as a function of the input power of the thermoelectric module. Under the present experimental conditions, the COP of the TED reached the maximum of 0.32 and the corresponding dehumidifying rate was 0.0097 g/min, when the input power was kept at 6.0 W. The rapid elimination of condensed liquid-drops on the cooling fins amounted on the thermoelectric module is a major approach to improving the operation performance of the TED.

  6. Variable Gravity Effects on the Cooling Performance of a Single Phase Confined Spray

    Science.gov (United States)

    Michalak, Travis; Yerkes, Kirk; Baysinger, Karri; McQuillen, John

    2005-01-01

    The objective of this paper is to discuss the testing of a spray cooling experiment designed to be flown on NASA's KC-135 Reduced Gravity Testing Platform. Spray cooling is an example of a thermal management technique that may be utilized in high flux heat acquisition and high thermal energy transport concepts. Many researchers have investigated the utility of spray cooling for the thermal management of devices generating high heat fluxes. However, there has been little research addressing the physics and ultimate performance of spray cooling in a variable gravity environment. An experimental package, consisting of a spray chamber coupled to a fluid delivery loop system, was fabricated for variable gravity flight tests. The spray chamber contains two opposing nozzles spraying on target Indium Tin Oxide (ITO) heaters. These heaters are mounted on glass pedestals, which are part of a sump system to remove unconstrained liquid from the test chamber. Liquid is collected in the sumps and returned to the fluid delivery loop. Thermocouples mounted in and around the pedestals are used to determine both the heat loss through the underside of the IT0 heater and the heat extracted by the spray. A series of flight tests were carried out aboard the KC-135, utilizing the ability of the aircraft to produce various gravity conditions. During the flight tests, for a fixed flow rate, heat input was varied at 20, 30, 50, and 80W with variable gravities of 0.01, 0.16, 0.36, and 1.8g. Flight test data was compared to terrestrial baseline data in addition to analytical and numerical solutions to evaluate the heat transfer in the heater and support structure . There were significant differences observed in the spray cooling performance as a result of variable gravity conditions and heat inputs. In general, the Nussult number at the heater surface was found to increase with decreasing gravity conditions for heat loads greater than 30W.

  7. Design Concepts for Cooled Ceramic Matrix Composite Turbine Vanes

    Science.gov (United States)

    Boyle, Robert

    2014-01-01

    This project demonstrated that higher temperature capabilities of ceramic matrix composites (CMCs) can be used to reduce emissions and improve fuel consumption in gas turbine engines. The work involved closely coupling aerothermal and structural analyses for the first-stage vane of a high-pressure turbine (HPT). These vanes are actively cooled, typically using film cooling. Ceramic materials have structural and thermal properties different from conventional metals used for the first-stage HPT vane. This project identified vane configurations that satisfy CMC structural strength and life constraints while maintaining vane aerodynamic efficiency and reducing vane cooling to improve engine performance and reduce emissions. The project examined modifications to vane internal configurations to achieve the desired objectives. Thermal and pressure stresses are equally important, and both were analyzed using an ANSYS® structural analysis. Three-dimensional fluid and heat transfer analyses were used to determine vane aerodynamic performance and heat load distributions.

  8. Performance of a radiatively cooled system for quantum optomechanical experiments in space

    CERN Document Server

    Pilan-Zanoni, André; Johann, Ulrich; Aspelmeyer, Markus; Kaltenbaek, Rainer; Hechenblaikner, Gerald

    2015-01-01

    The performance of a radiatively cooled instrument is investigated in the context of optomechanical quantum experiments, where the environment of a macroscopic particle in a quantum-superposition has to be cooled to less than 20\\,K in deep space. A heat-transfer analysis between the components of the instrument as well as a transfer-function analysis on thermal oscillations induced by the spacecraft interior and by dissipative sources is performed. The thermal behaviour of the instrument in an orbit around a Lagrangian point and in a highly elliptical Earth orbit is discussed. Finally, we investigate further possible design improvements aiming at lower temperatures of the environment of the macroscopic particle. These include a mirror-based design of the imaging system on the optical bench and the extension of the heat shields.

  9. Performance Analysis of Photovoltaic Panels with Earth Water Heat Exchanger Cooling

    Directory of Open Access Journals (Sweden)

    Jakhar Sanjeev

    2016-01-01

    Full Text Available The operating temperature is an important factor affecting the performance and life span of the Photovoltaic (PV panels. The rising temperature can be maintained within certain limit using proper cooling techniques. In the present research a novel system for cooling of PV panels named as Earth Water Heat Exchanger (EWHE is proposed and modelled in transient analysis simulation tool (TRNSYS v17.0 for the conditions of Pilani, Rajasthan (India.The various parameters which include cell temperature, PV power output and cell efficiency are observed with respect to variation in mass flow rate of fluid. Simulation results of the system without cooling show that the maximum PV panel temperature reached up to 79.31 °C with electrical efficiency dropped to 9% during peak sunshine hour. On the other hand, when PV panels are coupled with EWHE system, the panel temperature drops to 46.29 °C with an efficiency improving to 11% for a mass flow rate of 0.022 kg/s. In the end the cooling potential of EWHE is found to be in direct correlation with mass flow rate. The proposed system is very useful for the arid regions of western India which are blessed with high solar insolation throughout the year.

  10. Effect of cooling rate on microstructure and compressive performance of AZ91 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    YANG Lin; FENG Hui; QIU Ke-qiang; CHEN Li-jia; LIU Zheng

    2006-01-01

    Effect of cooling rate on both microstructure and room temperature compressive performance of the AZ91 magnesium alloy was investigated. The experimental results show that with increasing cooling rate, the quantity of the solid solution phase increases and the fraction of secondary phase Mg17Al12 decreases. The almost single solid solution phase can be obtained with using liquid nitrogen as a coolant. The compressive strengths of the rapid solidified AZ91 magnesium alloys are higher than those of normal cast alloy, and decrease with increasing cooling rate. After artificial aging treatment for 14 h at 168 ℃, the compressive strength of the rapidly solidified AZ91 magnesium alloy cooled in liquid nitrogen increases from 253.5 to 335.3 MPa, while the compressive yield strength increases from 138.1 to 225.91 MPa. The improvement in the compressive strength of the rapidly solidified AZ91magnesium alloys can be attributed to the hardening effect from fine secondary phase.

  11. Temperature-related performance of Yb3+:YAG disc lasers and optimum design for diamond cooling

    Institute of Scientific and Technical Information of China (English)

    Cao Ding-Xiang; Yu Hai-Wu; Zheng Wan-Guo; He Shao-Bo; Wang Xiao-Feng

    2006-01-01

    In this paper the temperature-related performances of the Yb3+:YAG disc laser has been investigated based on quasi-three level rate equation model. A compact diamond window cooling scheme also has been demonstrated. In this cooling scheme, laser disc is placed between two thin discs of single crystal synthetic diamond, the heat transfer from Yb3+:YAG to the diamond, in the direction of the optical axis, and then rapidly conducted radically outward through the diamond to the cooling water at the circumference of the diamond/Yb3+ :YAG assembly. Simulation results show that increasing the thickness of the diamond and the overlap-length (between diamond and water) decreases the disc temperature. Therefore a 0.3-0.5 mm thick diamond window with the overlap-length of 1.5-2.0 mm will provide acceptable cost effective cooling, e.g., with a pump intensity of 15 kW/cm2 and repetitive rate of 10 Hz, to keep the maximum temperature of the lasing disc below a reasonable value (310K), the heat exchange coefficient of water should be about 3000 W/m2K.

  12. Effect of solar radiation on the performance of cross flow wet cooling tower in hot climate of Iran

    Science.gov (United States)

    Banooni, Salem; Chitsazan, Ali

    2016-11-01

    In some cities such as Ahvaz-Iran, the solar radiation is very high and the annual-mean-daily of the global solar radiation is about 17.33 MJ m2 d-1. Solar radiation as an external heat source seems to affect the thermal performance of the cooling towers. Usually, in modeling cooling tower, the effects of solar radiation are ignored. To investigate the effect of sunshade on the performance and modeling of the cooling tower, the experiments were conducted in two different states, cooling towers with and without sunshade. In this study, the Merkel's approach and finite difference technique are used to predict the thermal behavior of cross flow wet cooling tower without sunshade and the results are compared with the data obtained from the cooling towers with and without sunshade. Results showed that the sunshade is very efficient and it reduced the outlet water temperature, the approach and the water exergy of the cooling tower up to 1.2 °C, 15 and 1.1 %, respectively and increased the range and the efficiency of the cooling tower up to 29 and 37 %, respectively. Also, the sunshade decreased the error between the experimental data of the cooling tower with sunshade and the modeling results of the cooling tower without sunshade 1.85 % in average.

  13. Cooling Performance Test of the SCT LV&HV Power Supply Rack

    CERN Document Server

    Böhm, J; Vacek, V

    2005-01-01

    The cooling performance test of the 52U rack, housing SCT LV&HV power supplies for 192 detector modules, being located in USA15 cavern, has been curried out. The rack was equipped with two air-water heat exchangers, air turbine, four vertical fan tray units under crates and horizontal fans in four Artesyn AC/DC power supply units. The resistive dummy loads for 192 power supply channels have been placed in four crates and housed in the adjacent rack.

  14. The Effect of Duct Level on the Performance of Reactor Vault Cooling System in the PGSFR

    Energy Technology Data Exchange (ETDEWEB)

    Yeom, Sujin; Ryu, Seung Ho; Kim, Dehee; Lee, Tae-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Development of the prototype gen-Ⅵ sodium-cooled fast reactor (PGSFR) has been ongoing in Korea Atomic Energy Research Institute (KAERI). A reactor vault cooling system (RVCS), one of passive decay heat removal systems (PDHRS), passively removes core decay heat by chimney effect when severe accidents occur. The air cooling path is located around containment vessel (CV). An air separator which divides the downstream air and the upstream air is installed between CV and the concrete wall. To design the RVCS, key design parameters such as stack height, gap size between the concrete wall and the air separator, gap size between the air separator and the CV, thickness and layer composition of the air separator have to be determined. A duct level is one of these design parameters. It denotes the height of the upstream air path and related to the heat transfer length from CV to air. The duct level should be optimized with considering structural reliability and heat removal performance. Thus, in this paper, the heat removal performance of RVCS is evaluated depends on the duct level using 1D system design code, that is developed by KAERI autonomously, and commercial CFD program for optimum design of RVCS In this paper, the heat removal performance of RVCS is evaluated depends on the duct level using PARS2- LMR code and commercial CFD program for optimum design of RVCS to satisfy both conflicting needs, structural reliability and cooling performance. As a result of PARS2-LMR code analysis, it was observed that the heat removal rate increases as increase of duct level and the geometrical conditions, that satisfy the design limitations, were obtained. To qualitatively observe the trends of local temperature distribution, CFD simulations were conducted and hotspots were observed at the upper region of ducts for the low duct level case.

  15. Natural aerodynamics

    CERN Document Server

    Scorer, R S

    1958-01-01

    Natural Aerodynamics focuses on the mathematics of any problem in air motion.This book discusses the general form of the law of fluid motion, relationship between pressure and wind, production of vortex filaments, and conduction of vorticity by viscosity. The flow at moderate Reynolds numbers, turbulence in a stably stratified fluid, natural exploitation of atmospheric thermals, and plumes in turbulent crosswinds are also elaborated. This text likewise considers the waves produced by thermals, transformation of thin layer clouds, method of small perturbations, and dangers of extra-polation.Thi

  16. Experimental study of cooling performance of pneumatic synthetic jet with singular slot rectangular orifice

    Science.gov (United States)

    Yu, Roger Ho Zhen; Ismail, Mohd Azmi bin; Ramdan, Muhammad Iftishah; Mustaffa, Nur Musfirah binti

    2017-03-01

    Synthetic Jet generates turbulence flow in cooling the microelectronic devices. In this paper, the experiment investigation of the cooling performance of pneumatic synthetic jet with single slot rectangular orifices at low frequency motion is presented. The velocity profile at the end of the orifice was measured and used as characteristic performance of synthetic jet in the present study. Frequencies of synthetic jet and the compressed air pressure supplied to the pneumatic cylinder (1bar to 5bar) were the parameters of the flow measurement. The air velocity of the synthetic jet was measured by using anemometer air flow meter. The maximum air velocity was 0.5 m/s and it occurred at frequency motion of 8 Hz. The optimum compressed air supplied pressure of the synthetic jet study was 4 bar. The cooling performance of synthetic jet at several driven frequencies from 0 Hz to 8 Hz and heat dissipation between 2.5W and 9W were also investigate in the present study. The results showed that the Nusselt number increased and thermal resistance decreased with both frequency and Reynolds number. The lowest thermal resistance was 5.25°C/W and the highest Nusselt number was 13.39 at heat dissipation of 9W and driven frequency of 8Hz.

  17. Unstructured Grid Euler Method Assessment for Longitudinal and Lateral/Directional Aerodynamic Performance Analysis of the HSR Technology Concept Airplane at Supersonic Cruise Speed

    Science.gov (United States)

    Ghaffari, Farhad

    1999-01-01

    Unstructured grid Euler computations, performed at supersonic cruise speed, are presented for a High Speed Civil Transport (HSCT) configuration, designated as the Technology Concept Airplane (TCA) within the High Speed Research (HSR) Program. The numerical results are obtained for the complete TCA cruise configuration which includes the wing, fuselage, empennage, diverters, and flow through nacelles at M (sub infinity) = 2.4 for a range of angles-of-attack and sideslip. Although all the present computations are performed for the complete TCA configuration, appropriate assumptions derived from the fundamental supersonic aerodynamic principles have been made to extract aerodynamic predictions to complement the experimental data obtained from a 1.675%-scaled truncated (aft fuselage/empennage components removed) TCA model. The validity of the computational results, derived from the latter assumptions, are thoroughly addressed and discussed in detail. The computed surface and off-surface flow characteristics are analyzed and the pressure coefficient contours on the wing lower surface are shown to correlate reasonably well with the available pressure sensitive paint results, particularly, for the complex flow structures around the nacelles. The predicted longitudinal and lateral/directional performance characteristics for the truncated TCA configuration are shown to correlate very well with the corresponding wind-tunnel data across the examined range of angles-of-attack and sideslip. The complementary computational results for the longitudinal and lateral/directional performance characteristics for the complete TCA configuration are also presented along with the aerodynamic effects due to empennage components. Results are also presented to assess the computational method performance, solution sensitivity to grid refinement, and solution convergence characteristics.

  18. Effects of Nozzle Geometry and Intermittent Injection of Aerodynamic Tab on Supersonic Jet Noise

    Science.gov (United States)

    Araki, Mikiya; Sano, Takayuki; Fukuda, Masayuki; Kojima, Takayuki; Taguchi, Hideyuki; Shiga, Seiichi; Obokata, Tomio

    Effects of the nozzle geometry and intermittent injection of aerodynamic tabs on exhaust noise from a rectangular plug nozzle were investigated experimentally. In JAXA (Japan Aerospace Exploration Agency), a pre-cooled turbojet engine for an HST (Hypersonic transport) is planned. A 1/100-scaled model of the rectangular plug nozzle is manufactured, and the noise reduction performance of aerodynamic tabs, which is small air jet injection from the nozzle wall, was investigated. Compressed air is injected through the rectangular plug nozzle into the atmosphere at the nozzle pressure ratio of 2.7, which corresponds to the take-off condition of the vehicle. Aerodynamic tabs were installed at the sidewall ends, and 4 kinds of round nozzles and 2 kinds of wedge nozzles were applied. Using a high-frequency solenoid valve, intermittent gas injection is also applied. It is shown that, by use of wedge nozzles, the aerodynamic tab mass flow rate, necessary to gain 2.3dB reduction in OASPL (Overall sound pressure level), decreases by 29% when compared with round nozzles. It is also shown that, by use of intermittent injection, the aerodynamic tab mass flow rate, necessary to gain 2.3dB reduction in OASPL, decreases by about 40% when compared with steady injection. By combination of wedge nozzles and intermittent injection, the aerodynamic tab mass flow rate significantly decreases by 57% when compared with the conventional strategy.

  19. Aerodynamic performance and particle image velocimetery of piezo actuated biomimetic manduca sexta engineered wings towards the design and application of a flapping wing flight vehicle

    Science.gov (United States)

    DeLuca, Anthony M.

    Considerable research and investigation has been conducted on the aerodynamic performance, and the predominate flow physics of the Manduca Sexta size of biomimetically designed and fabricated wings as part of the AFIT FWMAV design project. Despite a burgeoning interest and research into the diverse field of flapping wing flight and biomimicry, the aerodynamics of flapping wing flight remains a nebulous field of science with considerable variance into the theoretical abstractions surrounding aerodynamic mechanisms responsible for aerial performance. Traditional FWMAV flight models assume a form of a quasi-steady approximation of wing aerodynamics based on an infinite wing blade element model (BEM). An accurate estimation of the lift, drag, and side force coefficients is a critical component of autonomous stability and control models. This research focused on two separate experimental avenues into the aerodynamics of AFIT's engineered hawkmoth wings|forces and flow visualization. 1. Six degree of freedom force balance testing, and high speed video analysis was conducted on 30°, 45°, and 60° angle stop wings. A novel, non-intrusive optical tracking algorithm was developed utilizing a combination of a Gaussian Mixture Model (GMM) and ComputerVision (OpenCV) tools to track the wing in motion from multiple cameras. A complete mapping of the wing's kinematic angles as a function of driving amplitude was performed. The stroke angle, elevation angle, and angle of attack were tabulated for all three wings at driving amplitudes ranging from A=0.3 to A=0.6. The wing kinematics together with the force balance data was used to develop several aerodynamic force coefficient models. A combined translational and rotational aerodynamic model predicted lift forces within 10%, and vertical forces within 6%. The total power consumption was calculated for each of the three wings, and a Figure of Merit was calculated for each wing as a general expression of the overall efficiency of

  20. Sensitivity analysis of the thermal performance of radiant and convective terminals for cooling buildings

    DEFF Research Database (Denmark)

    Le Dréau, J.; Heiselberg, P.

    2014-01-01

    on both radiation and convection. In order to characterise the advantages and drawbacks of the different terminals, steady-state simulations of a typical office room have been performed using four types of terminals (active chilled beam, radiant floor, wall and ceiling). A sensitivity analysis has been...... conducted to determine the parameters influencing their thermal performance the most. The air change rate, the outdoor temperature and the air temperature stratification have the largest effect on the cooling need (maintaining a constant operative temperature). For air change rates higher than 0.5 ACH...

  1. Measured performance of a 3 ton LiBr absorption water chiller and its effect on cooling system operation

    Science.gov (United States)

    Namkoong, D.

    1976-01-01

    A three ton lithium bromide absorption water chiller was tested for a number of conditions involving hot water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It was concluded that a three-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

  2. Measured performance of a 3-ton LiBr absorption water chiller and its effect on cooling system operation

    Science.gov (United States)

    Namkoong, D.

    1976-01-01

    A 3-ton lithium bromide absorption water chiller was tested for a number of conditions involving hot-water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It is concluded that a 3-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

  3. Coupling model and solving approach for performance evaluation of natural draft counter-flow wet cooling towers

    Directory of Open Access Journals (Sweden)

    Wang Wei

    2016-01-01

    Full Text Available When searching for the optimum condenser cooling water flow in a thermal power plant with natural draft cooling towers, it is essential to evaluate the outlet water temperature of cooling towers when the cooling water flow and inlet water temperature change. However, the air outlet temperature and tower draft or inlet air velocity are strongly coupled for natural draft cooling towers. Traditional methods, such as trial and error method, graphic method and iterative methods are not simple and efficient enough to be used for plant practice. In this paper, we combine Merkel equation with draft equation, and develop the coupled description for performance evaluation of natural draft cooling towers. This model contains two inputs: the cooling water flow, the inlet cooling water temperature and two outputs: the outlet water temperature, the inlet air velocity, equivalent to tower draft. In this model, we furthermore put forward a soft-sensing algorithm to calculate the total drag coefficient instead of empirical correlations. Finally, we design an iterative approach to solve this coupling model, and illustrate three cases to prove that the coupling model and solving approach proposed in our paper are effective for cooling tower performance evaluation.

  4. Prediction of aerodynamic performance for MEXICO rotor%MEXICO风轮的气动性能预测

    Institute of Scientific and Technical Information of China (English)

    洪泽东; 杨华; 徐浩然; 沈文忠

    2013-01-01

    动量叶素法(blade element momentum,BEM)和计算流体力学方法(computational fluid dynamics,CFD)是预测风力机气动性能的常用方法,本文基于商用MATLAB和CFX软件,对MEXICO(Model Experiments In Controlled Conditions)风轮5种风速的轴向入流工况分别采用BEM和CFD方法进行气动性能预测,其中BEM方法计算时采用Shen叶尖修正,CFD方法选用SST紊流模型求解三维雷诺时均方程。研究表明,BEM和CFD方法计算的攻角最大相对误差分别为-0.402、0.099,试验获得的来流攻角沿叶片径向分布基本处于2种方法获得的结果之间,且在叶尖处更接近CFD计算的结果;试验获得的叶片轴向力沿叶片径向分布与2种方法的预测结果基本吻合,BEM和CFD 2种方法计算的轴向力最大相对误差分别为-0.139、-0.096,当叶片进入失速状态后,BEM方法计算的切向力最大相对误差达到-0.471,表明BEM方法的预测精度有待进一步提高,研究成果可为工程模型的修正与开发提供参考。%The aerodynamic performance of the MEXICO (Model EXperiments In Controlled cOnditions) rotor at five tunnel wind speeds is predicted by making use of BEM and CFD methods, respectively, using commercial MATLAB and CFD software. Due to the pressure differences on both sides of the blade, the tip-flow will produce secondary flow along the blade, consecutively resulting in decreases of torque. To overcome the above-mentioned issue, a variety of tip-correction models are developed, while most models overestimate the axial and tangential forces. To optimize accuracy, a new correction model summarized from CFD results by Shen is adopted in this paper. In order to accurately simulate the separation point and the separation area which is caused by the adverse pressure gradient, the CFD method using SST turbulence model is used to solve the three-dimensional Reynolds averaged equations. The first order upwind is used

  5. Performance of introducing outdoor cold air for cooling a plant production system with artificial light

    Directory of Open Access Journals (Sweden)

    Jun eWang

    2016-03-01

    Full Text Available The commercial use of a plant production system with artificial light (PPAL is limited by its high initial construction and operation costs. The electric-energy consumed by heat pumps, applied mainly for cooling, accounts for 15-35% of the total electric-energy used in a PPAL. To reduce the electric-energy consumption, an air exchanger with low capacity (180 W was used for cooling by introducing outdoor cold air. In this experiment, the indoor air temperature in two PPALs (floor area: 6.2 m2 each was maintained at 25ºC and 20ºC during light and dark periods, respectively, for lettuce production. In one PPAL (PPALe, an air exchanger (air flow rate: 250 m3 h-1 was used along with a heat pump (cooling capacity: 3.2 kW to maintain the indoor air temperature at the set-point. The other PPAL (PPALc with only a heat pump (cooling capacity: 3.2 kW was used for reference. Effects of introducing outdoor cold air on energy use efficiency, coefficient of performance (COP, electric-energy consumption for cooling and growth of lettuce were investigated. The results show that: when the air temperature difference between indoor and outdoor ranged from 20.2°C to 30.0°C: 1 the average energy use efficiency of the air exchanger was 2.8 and 3.4 times greater than the COP of the heat pumps in the PPALe and PPALc, respectively; 2 hourly electric-energy consumption in the PPALe reduced by 15.8-73.7% compared with that in the PPALc; 3 daily supply of CO2 in the PPALe reduced from 0.15 kg to 0.04 kg compared with that in the PPALc; 4 no significant difference in lettuce growth was observed in both PPALs. The results indicate that using air exchanger to introduce outdoor cold air should be considered as an effective way to reduce electric-energy consumption for cooling with little effects on plant growth in a PPAL.

  6. Aerodynamic Performance Test of Centrifugal Compressor Unit for LNG%LNG用离心式压缩机组气动性能试验技术研究

    Institute of Scientific and Technical Information of China (English)

    赵新君

    2013-01-01

      LNG是液化天然气(Liquefied Natural Gas)的简称。由于受天然气组分和现场工艺装置的影响,在用户现场很难实现对压缩机气动性能的考核,因此为了评估该类产品的设计、制造质量,采用R134a代用气体在压缩机制造厂内进行气动性能试验,本文从试验方法的论证和试验装置的设计以及试验的评估做了较为详细的介绍。并以机械工程学会动力试验规程ASMEP TC10进行试验和计算,最终得到LNG压缩机气动性能曲线。%  LNG is the abbreviation of Liquefied Natural Gas. Affected by the component of natural gas and site process installation, it is difficult to check the compressor aerodynamic performance on users’ site. Therefore, to estimate the quality of design and manufacture of this kind of products, the alternative gas will be used to carry out aerodynamic performance test in compressor’s manufacturers. This paper has made a detail introduction from the aspects of the demonstration of test method, the design of test installation and the test estimation. And according to the ASME T10 Test Procedures of Machinery Engineering Association, the test and calculation is carried out, and the LNG compressor aerodynamic performance curve is obtained.

  7. Cooling performance and evaluation of automotive refrigeration system for a passenger car

    Science.gov (United States)

    Prajitno, Deendarlianto, Majid, Akmal Irfan; Mardani, Mahardeka Dhias; Wicaksono, Wendi; Kamal, Samsul; Purwanto, Teguh Pudji; Fauzun

    2016-06-01

    A new design of automotive refrigeration system for a passenger car was proposed. To ensure less energy consumption and optimal thermal comfort, the performance of the system were evaluated. This current research was aimed to evaluate the refrigeration characteristics of the system for several types of cooling load. In this present study, a four-passenger wagon car with 1500 cc gasoline engine that equipped by a belt driven compressor (BDC) was used as the tested vehicle. To represent the tropical condition, a set of lamps and wind sources are installed around the vehicle. The blower capacity inside a car is varied from 0.015 m/s to 0.027 m/s and the compressor speed is varied at variable 820, 1400, and 2100 rpm at a set temperature of 22°C. A set of thermocouples that combined by data logger were used to measure the temperature distribution. The system uses R-134a as the refrigerant. In order to determine the cooling capacity of the vehicle, two conditions were presented: without passengers and full load conditions. As the results, cooling capacity from any possible heating sources and transient characteristics of temperature in both systems for the cabin, engine, compressor, and condenser are presented in this work. As the load increases, the outlet temperature of evaporator also increases due to the increase of condensed air. This phenomenon also causes the increase of compressor work and compression ratio which associated to the addition of specific volume in compressor inlet.

  8. Effects of whole body cooling on sensory perception and manual performance in subjects with Raynaud's phenomenon.

    Science.gov (United States)

    Rissanen, S; Hassi, J; Juopperi, K; Rintamäki, H

    2001-04-01

    Patients with Raynaud's phenomenon (RP) have abnormal digital vasoconstriction in response to cold. The aim of the study was to investigate the effects of cooling on sensory perception and manual performance in healthy male subjects and subjects with RP. There were two groups of subjects with primary RP: 12 subjects fulfilled the criteria of Lewis (L) and the other 12 the more critical criteria of Maricq (M). Control group (C) consisted of 19 healthy men. Subjects were exposed to 5 degrees C for 60 min. Skin temperatures were measured. Finger dexterity, pinch strength, abduction/adduction of fingers, pressure perception threshold and vibration perception threshold were tested during the exposure every 15 min. At the beginning of the exposure the mean (S.E.) finger temperature was 2.5 (1.2) degrees C (Pperception were impaired due to the cooling, the impairment being significantly greater in M than in C. Responses of L were between those of M and C. In a given finger temperature vibration and pressure sensibility and manual performance were lower in M and L than in C. In conclusion, cold exposure decreased sensory perception and manual performance in the subjects with RP to a lower level than in the healthy subjects. Non-thermal factors may also decrease performance in RP.

  9. CARMENES-NIR channel spectrograph cooling system AIV: thermo-mechanical performance of the instrument

    Science.gov (United States)

    Becerril, S.; Mirabet, E.; Lizon, J. L.; Abril, M.; Cárdenas, C.; Ferro, I.; Morales, R.; Pérez, D.; Ramón, A.; Sánchez-Carrasco, M. A.; Quirrenbach, A.; Amado, P.; Ribas, I.; Reiners, A.; Caballero, J. A.; Seifert, W.; Herranz, J.

    2016-07-01

    CARMENES is the new high-resolution high-stability spectrograph built for the 3.5m telescope at the Calar Alto Observatory (CAHA, Almería, Spain) by a consortium formed by German and Spanish institutions. This instrument is composed by two separated spectrographs: VIS channel (550-1050 nm) and NIR channel (950- 1700 nm). The NIR-channel spectrograph's responsible is the Instituto de Astrofísica de Andalucía (IAACSIC). It has been manufactured, assembled, integrated and verified in the last two years, delivered in fall 2015 and commissioned in December 2015. One of the most challenging systems in this cryogenic channel involves the Cooling System. Due to the highly demanding requirements applicable in terms of stability, this system arises as one of the core systems to provide outstanding stability to the channel. Really at the edge of the state-of-the-art, the Cooling System is able to provide to the cold mass ( 1 Ton) better thermal stability than few hundredths of degree within 24 hours (goal: 0.01K/day). The present paper describes the Assembly, Integration and Verification phase (AIV) of the CARMENES-NIR channel Cooling System implemented at IAA-CSIC and later installation at CAHA 3.5m Telescope, thus the most relevant highlights being shown in terms of thermal performance. The CARMENES NIR-channel Cooling System has been implemented by the IAA-CSIC through very fruitful collaboration and involvement of the ESO (European Southern Observatory) cryo-vacuum department with Jean-Louis Lizon as its head and main collaborator. The present work sets an important trend in terms of cryogenic systems for future E-ELT (European Extremely Large Telescope) large-dimensioned instrumentation in astrophysics.

  10. 气动悬浮冷速控制及Al-7.7Ca共晶合金的凝固组织%COOLING RATE CONTROL AND SOLIDIFIED MICROSTRUCTURE OF Al-7.7Ca EUTECTIC ALLOY DURING AERODYNAMIC LEVITATION

    Institute of Scientific and Technical Information of China (English)

    张龙; 张曙光; 余建定; 李建国

    2013-01-01

    The aerodynamic levitation process, which possesses the advantages of con-tainerless solidification, easy control and versatility to materials, is a kind of advanced materials processing technology. How to accurately control the cooling rate during aerodynamic levitation is quite important for studying the processing-structure-property relationship of metallic materials. In this study, the characteristics of laser absorption, thermal radiation and heat convection of an aerodynamically levitated sample were analyzed, and a formula for the control of the cooling rate by means of tuning the laser power has been derived, which is described by: △T/△t= -3[σε(T4s - T4f) + h(Ts - T0)]/cpr + a(6Ls - 3k△t)/8cpπγ3. By recording temperature-time curves with cooling rates of 9, 49, 98 and 253 ℃/s for the aerodynamically levitated Al-7.7Ca (mass fraction, %) eutectic alloy, the calculated values of cooling rates agree very well with the experimental data, verifying and validating the formula. Also, the microstructure of the aerodynamically levitated Al-7.7Ca eutectic alloy under different cooling rates was examined using OM and SEM. The met-allographic observation shows that, under a low cooling rate of 9 ℃/s, the solidification structure of Al-7.7Ca alloy during aerodynamic levitation exhibits lamellar regular eutectic. With increasing the cooling rate, the undercooling measured from the recorded temperature-time curves increases, resulting in the refinement of the grain size and interlamellar spacing of regular eutectic. Moreover, there appears granular anomalous eutectic under higher cooling rates of 49, 98 and 253 ℃/s. The volume fraction of anomalous eutectic is increased with increasing the cooling rate. The anomalous eutectic is attributed to the formation during the rapid solidification stage. By measuring the interlamellar spacing of regular eutectic from Al-7.7Ca metallographs, the fitting data of interlamellar spacing and undercooling are in accordance

  11. Comparative study on thermal performance of natural draft cooling towers with finned shells

    Energy Technology Data Exchange (ETDEWEB)

    Goodarzi, Mohsen [Bu-Ali Sina Univ., Hamedan (Iran, Islamic Republic of). Dept. of Mechanical Engineering

    2016-10-15

    The cooling efficiency of natural draft cooling towers under crosswind condition should be improved. In the present research work three different externally finned shells were considered for a typical natural draft cooling tower to investigate the cooling improvement. They were numerically simulated under normal and crosswind conditions. Numerical results show that twisting four fin plates over the tower shell along the 45 peripheral angle, could improve the cooling efficiency up to 6.5 %. Because of the periodic shape of the fin plates, the cooling efficiency of the cooling tower with finned shell is less sensitive to the change of wind.

  12. Experimental study on the aerodynamic performance of 3-dimensional vortex-blowers. Sanjigen uzuryu blower no kuriki seino ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, S.; Ito, E.; Fujio, M.; Fujita, H. (Hitachi, Ltd., Tokyo (Japan))

    1992-10-25

    Vortex blowers with two-dimensional blades have such deficiencies as low aerodynamic performance and high noise. Accordingly, discussions have been given on effects of three-dimensionalized blades on internal flows and aerodynamic performance with the objective of making the vortex blowers smaller in size, higher in performance, and lower in noise. A spiral flow exists in the flow path in a casing, which has its flow velocity increased as the flow rate is decreased. The flow velocity at the closing point reaches about two times as large as the circumferential speed of the blades in the case of having three-dimensional leading blades. The spiral flow outflowing from outer circumference of the blades into the casing flow path has its flow velocity nearly halved while swirling in semi-circular form in the casing flow path, by which a vortex blower converts the total pressure in the casing flow path to a static pressure. When the outlet angle in the axial direction is changed from 90[degree] (two-dimensional blade) to 50[degree](three-dimensional leading blade), the flow velocity components increase largely in the circumferential direction, with the pressure coefficient and the dynamic coefficient increasing by about two fold respectively. When the inlet angle in the axial direction is reduced to 40[degree] , the blade incident loss reduces, while the pressure coefficient improves by about 20% and the heat insulation efficiency by about 30%. 4 refs., 15 figs., 1 tab.

  13. The Effect of the Phase Angle between the Forewing and Hindwing on the Aerodynamic Performance of a Dragonfly-Type Ornithopter

    Directory of Open Access Journals (Sweden)

    Hidetoshi Takahashi

    2016-01-01

    Full Text Available Dragonflies achieve agile maneuverability by flapping four wings independently. Different phase angles between the flapping forewing and hindwing have been observed during various flight modes. The aerodynamic performance depends on phase angle control, as exemplified by an artificial flying ornithopter. Here, we present a dragonfly-like ornithopter whose phase angle was designed to vary according to the phase lag between the slider-cranks of the forewing and hindwing. Two microelectromechanical systems (MEMS differential pressure sensors were attached to the center of both forewing and hindwing to evaluate the aerodynamic performance during flapping motions when the phase angle was changed. By varying the phase angle in both the tethered condition and free-flight, the performance of the forewing remained approximately constant, whereas that of the hindwing exhibited obvious variations; the maximum average value was two-fold higher than the minimum. The experimental results suggest that simple phase angle changes enable a flying ornithopter to control flight force balance without complex changes in the wing kinematics.

  14. Comparative Effectiveness of Different Phase Change Materials to Improve Cooling Performance of Heat Sinks for Electronic Devices

    Directory of Open Access Journals (Sweden)

    Ahmad Hasan

    2016-08-01

    Full Text Available This paper thermo-physically characterizes salt hydrate, paraffin wax and milk fat as phase change materials (PCMs. The three PCMs are compared in terms of improving heat sink (HS performance for cooling electronic packaging. An experimental study is carried out on commercially available finned HS with and without PCM under natural ventilation (NV and forced ventilation (FV at different heat loads (4 W to 10 W. The results indicate that integration of all of the PCMs into the HS improves its cooling performance; however, milk fat lags behind the other two PCMs in terms of cooling produced. A three-dimensional pressure-based conjugate heat transfer model has been developed and validated with experimental results. The model predicts the parametric influence of PCM melting range, thermal conductivity and density on HS thermal management performance. The HS cooling performance improves with increased density and conductivity while it deteriorates with the wider melting range of the PCMs.

  15. Lagrangian and Control Volume Models for Prediction of Cooling Lake Performance at SRP

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, A.J.

    2001-06-26

    The model validation described in this document indicates that the methods described here and by Cooper (1984) for predicting the performance of the proposed L-Area cooling lake are reliable. Extensive observations from the Par Pond system show that lake surface temperatures exceeding 32.2 degrees C (90 degrees F) are attained occasionally in the summer in areas where there is little or no heating from the P-Area Reactor. Regulations which restrict lake surface temperatures to less than 32.2 degrees C should be structured to allow for these naturally-occurring thermal excursions.

  16. Performance evaluation of a stack cooling system using CO{sub 2} air conditioner in fuel cell vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Chul; Won, Jong Phil [Thermal Management Research Center, Korea Automotive Technology Institute, Chungnam 330-912 (Korea); Park, Yong Sun; Lim, Tae Won [Corporate Research and Development Division, Hyundai-Kia Motors, Gyeonggi 449-912 (Korea); Kim, Min Soo [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744 (Korea)

    2009-01-15

    A relation between the heat release from a fuel cell stack and an air conditioning system's performance was investigated. The air conditioning system installed in a fuel cell vehicle can be used for stack cooling when additional stack heat release is required over a fixed radiator capacity during high vehicle power generation. This study investigated the performance of a stack cooling system using CO{sub 2} air conditioner at various operating conditions. Also, the heat releasing effectiveness and mutual interference were analyzed and compared with those for the conventional radiator cooling system with/without cabin cooling. When the radiator coolant inlet temperature and flow rate were 65 C and 80 L/min, respectively, for the outdoor air inlet speed of 5 m/s, the heat release of the stack cooling system with the aid of CO{sub 2} air conditioner increased up to 36% more than that of the conventional radiator cooling system with cabin cooling. Furthermore, this increased by 7% versus the case without cabin cooling. (author)

  17. Heat transfer and performance characteristics of axial cooling fans with downstream guide vanes

    Science.gov (United States)

    Terzis, Alexandros; Stylianou, Ioannis; Kalfas, Anestis I.; Ott, Peter

    2012-04-01

    This study examines experimentally the effect of stators on the performance and heat transfer characteristics of small axial cooling fans. A single fan impeller, followed by nine stator blades in the case of a complete stage, was used for all the experimental configurations. Performance measurements were carried out in a constant speed stage performance test rig while the transient liquid crystal technique was used for the heat transfer measurements. Full surface heat transfer coefficient distributions were obtained by recording the temperature history of liquid crystals on a target plate. The experimental data indicated that the results are highly affected by the flow conditions at the fan outlet. Stators can be beneficial in terms of pressure drop and efficiency, and thus more economical operation, as well as, in the local heat transfer distribution at the wake of the stator blades if the fan is installed very close to the cooling object. However, as the separation distance increases, enhanced heat transfer rate in the order of 25% is observed in the case of the fan impeller.

  18. Gas turbine performance enhancement via utilizing different integrated turbine inlet cooling techniques

    Directory of Open Access Journals (Sweden)

    Alaa A. El-Shazly

    2016-09-01

    Full Text Available Regions that experience ambient temperatures rising during hot seasons have significant losses and impacts on both output power and efficiency of the gas turbine. When the ambient temperature increases, the air mass flow rate decreases, and hence leads to reduce the gas turbine produced power. Ambient air can be cooled by using either evaporative cooler or absorption chiller. Currently, the performance was simulated thermodynamically for a natural gas operated gas turbine. The performance was tested for the base case without any turbine inlet cooling (TIC systems and compared with the performance for both evaporative cooler and absorption chiller separately in terms of output power, thermal efficiency, heat rate, specific fuel consumption, consumed fuel mass flow rate, and economics. Results showed that at air ambient temperature equals to 37 °C and after deducting all the associated auxiliaries power consumption for both evaporative cooler and absorption chiller, the absorption chiller with regenerator can achieve an augmentation of 25.47% in power and 33.66% in efficiency which provides a saving in average power price about 13%, while the evaporative cooler provides only an increase of 5.56% in power and 1.55% in efficiency, and a saving of 3% in average power price.

  19. Performance evaluation of combined ejector LiBr/H2O absorption cooling cycle

    Directory of Open Access Journals (Sweden)

    Hasan Sh. Majdi

    2016-03-01

    Full Text Available The objective of this work is to develop a computer simulation program to evaluate the performance of solar-assited combined ejector absorption (single-effect cooling system using LiBr/H2O as a working fluid and operating under steady-state conditions. The ejector possess no moving parts and is simple and reliable, which makes it attractive for combination with single-stage absorption cycle for further improvement to the system's performance. In this research, improvement to the system is achieved by utilizing the potential kinetic energy of the ejector to enhance refrigeration efficiency. The effects of the entrainment ratio of the ejector, operating temperature, on the thermal loads, and system performance have been investigated. The results showed that the evaporator and condenser loads, post-addition of the ejector, is found to be permanently higher than that in the basic cycle, which indicates a significant enhancement of the proposed cycle and the cooling capacity of the system increasing with the increase in evaporator temperature and entrainment ratio. The COP of the modified cycle is improved by up to 60 % compared with that of the basic cycle at the given condition. This process stabilizes the refrigeration system, enhanced its function, and enabled the system to work under higher condenser temperatures.

  20. Assessment of thermal performance for the design of a passively-cooled plutonium storage vault

    Science.gov (United States)

    Sanders, Joseph Conway

    A passively-cooled plutonium storage vault, rather than one with a safety-qualified, forced-flow cooling system, could save as much as 100 million over the project lifetime. Either configuration must maintain the temperature of the stored plutonium metal, with its significant internal heat generation, below 239 sp circF. Alpha-phase metal, if allowed to exceed this temperature, will transition to beta-phase metal and undergo a volumetric expansion which could rupture the storage container system. An investigation was performed to determine whether a passively-cooled vault is feasible. Significant temperature drops occurred in two regions, both were gas-filled vertical annuli with heat flux boundary conditions on the inner surfaces and fixed temperature boundary conditions on the outer surfaces. The thermal resistance method was employed to evaluate radial heat transfer across each annulus, coupling natural convection, radiation, and conduction. Correlations from Thomas et al and Kulacki et al were used to evaluate the degree of natural convective enhancement. For the helium-filled region between the plutonium metal rod and the container with a characteristic length of 3.9 centimeters and an aspect ratio of 5.6, the Rayleigh number was 800 when the effect of radiation was removed. This resulted in a Nusselt number of 1.8. For the air-filled region between twelve vertically arranged containers and the storage tube with a characteristic length of 5.8 centimeters and an aspect ratio of 78, the Rayleigh number was 5times10sp5. This resulted in a Nusselt number of approximately 4.5, neglecting the effect of radiation. FIDAP 7.62\\copyright$ (Fluid Dynamics Analysis Package) was used to perform multi-dimensional finite element analyses of these regions employing both buoyant and radiative effects. Both simplified and more geometrically complex models were employed, all of which compared favorably to the results using the thermal resistance method. The results of the

  1. Performance Evaluation of an In-Wheel Motor Cooling System in an Electric Vehicle/Hybrid Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Dong Hyun Lim

    2014-02-01

    Full Text Available High power and miniaturization of motors in an in-wheel drive system, which is installed inside the wheels of a vehicle, are required for directly driving the wheels. In addition, an efficient cooling system is required to ensure high driving performance and durability. This study experimentally evaluated the heat dissipation performance of a 35-kW-class large-capacity in-wheel motor equipped with an internal-circulation-type oil-cooling system that exhibits high cooling performance and can be easily miniaturized to this motor. Temperatures of the coil and stator core of cooling systems with and without a radiator were measured in real time under in-wheel motor driving conditions. It was found that operating the cooling system at a continuous-rating maximum speed without the radiator was difficult. We confirmed that under continuous-rating base speed and continuous-rating maximum speed driving conditions, the cooling system with the radiator showed thermally stable operation. Furthermore, under maximum-rating base speed and maximum-rating maximum speed driving conditions, the cooling system with the radiator provided additional driving times of approximately 22 s and 2 s, respectively.

  2. Mechanisms research of rain effects on airfoil aerodynamic performance%降雨对翼型气动性能影响的机理研究

    Institute of Scientific and Technical Information of China (English)

    张瑞民; 曹义华

    2011-01-01

    利用计算流体力学软件FLUENT 6.3.26中的拉格朗日离散相模型研究了降雨条件下翼型的气动特性变化,并应用UDF(用户自定义函数)对FLUENT中自带的Wilcox转捩模式进行了修正,对降雨对翼型气动性能的影响机理进行了研究.结果表明,在降雨条件下,翼型表面积聚的水膜层及其表面粗糙度会影响翼型表面的光洁度,引起边界层提前转捩,造成升力系数略微减小,阻力系数增加;当翼型接近失速时,聚集在翼型上表面尾缘处的水膜层会触发边界层气流的提前分离,造成翼犁气动性能的严重损失.%The aerodynamic characteristics of an airfoil in rain condition were studied with the Lagrangian discrete phase model in the computational fluid dynamics soft ware FLUENT 6. 3.26. The mechanism of rain effects on airfoil aerodynamic performance was also investigated based on modifying the Wilcox transition mode with a UDF (user-defined function). It is shown that the water film accumulated on airfoil surfaces and the film roughness can influence the smoothness of the airfoil surfaces and induce premature transition. Thus the lift coefficients decrease lightly and the drag coefficients increase; when the airfoil approaches stalling, the water film accumulated on the trailing edge of the upper surface can trigger the advanced separation of boundary airflow and cause the serious aerodynamic penalty.

  3. Aerodynamic Aspects of Wind Energy Conversion

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær

    2011-01-01

    This article reviews the most important aerodynamic research topics in the field of wind energy. Wind turbine aerodynamics concerns the modeling and prediction of aerodynamic forces, such as performance predictions of wind farms, and the design of specific parts of wind turbines, such as rotor......-blade geometry. The basics of the blade-element momentum theory are presented along with guidelines for the construction of airfoil data. Various theories for aerodynamically optimum rotors are discussed, and recent results on classical models are presented. State-of-the-art advanced numerical simulation tools...

  4. The Effects of Inlet Box Aerodynamics on the Mechanical Performance of a Variable Pitch in Motion Fan

    Directory of Open Access Journals (Sweden)

    A. G. Sheard

    2012-01-01

    Full Text Available This paper describes research involving an in-service failure of a “variable pitch in motion” fan’s blade bearing. Variable pitch in motion fans rotate at a constant speed, with the changing blade angle varying the load. A pitch-change mechanism facilitates the change in blade angle. A blade bearing supports each blade enabling it to rotate. The author observed that as the fan aerodynamic stage loading progressively increased, so did the rate of blade-bearing wear. The reported research addressed two separate, but linked, needs. First, the ongoing need to increase fan pressure development capability required an increase in fan loading. This increase was within the context of an erosive operating regime which systematically reduced fan pressure development capability. The second need was to identify the root cause of blade-bearing failures. The author addressed the linked needs using a computational analysis, improving the rotor inflow aerodynamic characteristics through an analysis of the inlet box and design of inlet guide vanes to control flow nonuniformities at the fan inlet. The results of the improvement facilitated both an increase in fan-pressure-developing capability and identification of the root cause of the blade-bearing failures.

  5. A Comparison of Mixed-Method Cooling Interventions on Preloaded Running Performance in the Heat.

    Science.gov (United States)

    Stevens, Christopher J; Bennett, Kyle J M; Sculley, Dean V; Callister, Robin; Taylor, Lee; Dascombe, Ben J

    2017-03-01

    Stevens, CJ, Bennett, KJM, Sculley, DV, Callister, R, Taylor, L, and Dascombe, BJ. A comparison of mixed-method cooling interventions on preloaded running performance in the heat. J Strength Cond Res 31(3): 620-629, 2017-The purpose of this investigation was to assess the effect of combining practical methods to cool the body on endurance running performance and physiology in the heat. Eleven trained male runners completed 4 randomized, preloaded running time trials (20 minutes at 70% V[Combining Dot Above]O2max and a 3 km time trial) on a nonmotorized treadmill in the heat (33° C). Trials consisted of precooling by combined cold-water immersion and ice slurry ingestion (PRE), midcooling by combined facial water spray and menthol mouth rinse (MID), a combination of all methods (ALL), and control (CON). Performance time was significantly faster in MID (13.7 ± 1.2 minutes; p < 0.01) and ALL (13.7 ± 1.4 minutes; p = 0.04) but not PRE (13.9 ± 1.4 minutes; p = 0.24) when compared with CON (14.2 ± 1.2 minutes). Precooling significantly reduced rectal temperature (initially by 0.5 ± 0.2° C), mean skin temperature, heart rate and sweat rate, and increased iEMG activity, whereas midcooling significantly increased expired air volume and respiratory exchange ratio compared with control. Significant decreases in forehead temperature, thermal sensation, and postexercise blood prolactin concentration were observed in all conditions compared with control. Performance was improved with midcooling, whereas precooling had little or no influence. Midcooling may have improved performance through an attenuated inhibitory psychophysiological and endocrine response to the heat.

  6. On the performance of air conditioner with heat pipe for cooling air in the condenser

    Energy Technology Data Exchange (ETDEWEB)

    Naphon, Paisarn, E-mail: paisarnn@swu.ac.t [Thermo-Fluids and Heat Transfer Enhancement Laboratory (TFHT), Department of Mechanical Engineering, Faculty of Engineering, Srinakharinwirot University, 63 Rangsit-Nakhornnayok Rd., Ongkharak, Nakhorn-Nayok 26120 (Thailand)

    2010-11-15

    Improvement of the air conditioning system performance by using the heat pipe for cooling air before entering the condenser is presented. In the experiment, the heat pipe is fabricated from the straight copper tube with the diameter and length of 10, 600 mm, respectively. The arrangements of the heat pipe sets are arranged in the staggered layout with the tube rows of 1, 2, 3. R134a refrigerant is used as working fluid in the heat pipe set for this present study. By comparing with a conventional air conditioning system, the air conditioning system with three rows of heat pipe gives the highest COP and EER with increasing of 6.4%, 17.5%, respectively. On the global warming and environment problems, the results of this study are expected to lead to guidelines that will allow the improved performance of the air conditioning systems which reduce its energy consumption.

  7. The performance of a temperature cascaded cogeneration system producing steam, cooling and dehumidification

    KAUST Repository

    Myat, Aung

    2013-02-01

    This paper discusses the performance of a temperature-cascaded cogeneration plant (TCCP), equipped with an efficient waste heat recovery system. The TCCP, also called a cogeneration system, produces four types of useful energy-namely, (i) electricity, (ii) steam, (iii) cooling and (iv) dehumidification-by utilizing single fuel source. The TCCP comprises a Capstone C-30 micro-turbine that generates nominal capacity of 26 kW of electricity, a compact and efficient waste heat recovery system and a host of waste-heat-activated devices, namely (i) a steam generator, (ii) an absorption chiller, (iii) an adsorption chiller and (iv) a multi-bed desiccant dehumidifier. The performance analysis was conducted under different operation conditions such as different exhaust gas temperatures. It was observed that energy utilization factor could be as high as 70% while fuel energy saving ratio was found to be 28%. © 2013 Desalination Publications.

  8. Cooling vest worn during active warm-up improves 5-km run performance in the heat.

    Science.gov (United States)

    Arngrïmsson, Sigurbjörn A; Petitt, Darby S; Stueck, Matthew G; Jorgensen, Dennis K; Cureton, Kirk J

    2004-05-01

    We investigated whether a cooling vest worn during an active warm-up enhances 5-km run time in the heat. Seventeen competitive runners (9 men, maximal oxygen uptake = 66.7 +/- 5.9 ml x kg(-1) x min(-1); 8 women, maximal oxygen uptake = 58.0 +/- 3.2 ml x kg(-1) x min(-1)) completed two simulated 5-km runs on a treadmill after a 38-min active warm-up during which they wore either a T-shirt (C) or a vest filled with ice (V) in a hot, humid environment (32 degrees C, 50% relative humidity). Wearing the cooling vest during warm-up significantly (P run, esophageal, rectal, mean skin, and mean body temperatures averaged 0.3, 0.2, 1.8, and 0.4 degrees C lower; HR averaged 11 beats/min lower; and perception of thermal discomfort (5-point scale) averaged 0.6 point lower in V than C. Most of these differences were eliminated during the first 3.2 km of the run, and these variables were not different at the end. The 5-km run time was significantly lower (P faster pace most evident during the last two-thirds of the run. We conclude that a cooling vest worn during active warm-up by track athletes enhances 5-km run performance in the heat. Reduced thermal and cardiovascular strain and perception of thermal discomfort in the early portion of the run appear to permit a faster pace later in the run.

  9. Dynamic behavior of radiant cooling system based on capillary tubes in walls made of high performance concrete

    DEFF Research Database (Denmark)

    Mikeska, Tomás; Svendsen, Svend

    2015-01-01

    using cooling water for the radiant cooling system with a temperature only about 4K lower than the temperature of the room air. The relatively high speed reaction of the designed system is a result of the slim construction of the sandwich wall elements made of high performance concrete. (C) 2015...... the small amount of fresh air required by standards to provide a healthy indoor environment.This paper reports on experimental analyses evaluating the dynamic behavior of a test room equipped with a radiant cooling system composed of plastic capillary tubes integrated into the inner layer of sandwich wall...

  10. Analysis of the Solar Radiation Impact on Cooling Performance of the Absorption Chiller

    Directory of Open Access Journals (Sweden)

    Fedorčák Pavol

    2014-11-01

    Full Text Available Absorption cooling at low power is a new technology which has not yet been applied to current conditioning elements. This paper analyzes the various elements of solar absorption cooling. Individual states were simulated in which working conditions were set for the capability of solar absorption cooling to balance heat loads in the room.

  11. Analysis of the Solar Radiation Impact on Cooling Performance of the Absorption Chiller

    OpenAIRE

    Fedorčák Pavol; Košičanová Danica; Nagy Richard; Mlynár Peter

    2014-01-01

    Absorption cooling at low power is a new technology which has not yet been applied to current conditioning elements. This paper analyzes the various elements of solar absorption cooling. Individual states were simulated in which working conditions were set for the capability of solar absorption cooling to balance heat loads in the room.

  12. Cool products for building envelope - Part II: Experimental and numerical evaluation of thermal performances

    NARCIS (Netherlands)

    Revel, G.M.; Martarelli, M.; Emiliani, M.; Celotti, L.; Nadalini, R.; Ferrari, A.D.; Hermanns, S.; Beckers, E.

    2014-01-01

    Cool materials have a large potential as cost-effective solution for reducing cooling energy consumption in hot summer and mild winter regions like Mediterranean countries. A previous paper has described in detail the development of cool coloured ceramic tiles, acrylic paints and bituminous membrane

  13. The performance of a mobile air conditioning system with a water cooled condenser

    Science.gov (United States)

    Di Battista, Davide; Cipollone, Roberto

    2015-11-01

    Vehicle technological evolution lived, in recent years, a strong acceleration due to the increased awareness of environmental issues related to pollutants and climate altering emissions. This resulted in a series of international regulations on automotive sector which put technical challenges that must consider the engine and the vehicle as a global system, in order to improve the overall efficiency of the system. The air conditioning system of the cabin, for instance, is the one of the most important auxiliaries in a vehicle and requires significant powers. Its performances can be significantly improved if it is integrated within the engine cooling circuit, eventually modified with more temperature levels. In this paper, the Authors present a mathematical model of the A/C system, starting from its single components: compressors, condenser, flush valve and evaporator and a comparison between different refrigerant fluid. In particular, it is introduced the opportunity to have an A/C condenser cooled by a water circuit instead of the external air linked to the vehicle speed, as in the actual traditional configuration. The A/C condenser, in fact, could be housed on a low temperature water circuit, reducing the condensing temperature of the refrigeration cycle with a considerable efficiency increase.

  14. Cool-down performance of the new apparatus for fuel layering demonstrations of FIREX targets

    Science.gov (United States)

    Iwamoto, A.; Norimatsu, T.; Nakai, M.; Sakagami, H.; Shiraga, H.; Azechi, H.

    2016-03-01

    FIREX targets have been developed under two layering strategies: foam shell and cone guide laser heating methods. Basic studies have been conducted by the collaboration research between ILE and NIFS. Then the next stage requires the characterization of a layered solid fuel. The present system is at the disadvantage of optical observations. Therefore, a new apparatus is designed to solve it. Glass windows with a wide aperture are installed for an interferometer and a microscope. To isolate the vibration from a cryocooler, active vibration control units are equipped, and flexible thermal conductive links are utilized. Furthermore, a quick target exchange mechanism is applied to deal with different types of FIREX targets. A target holder is detachable from a main vacuum chamber. A metal gasket with not fixing bolts but a load of ∼ thousand newtons on ensures GHe leak tightness for target cooling. Eventually, the design temperature of 10.00 K at a target container has been achieved. The cool-down performance indecates that the new apparatus provides a cryogenic environment for fuel layering demonstrations.

  15. Heat-moisture performance of cool polyamide fibers%凉爽锦纶纤维的热湿性能

    Institute of Scientific and Technical Information of China (English)

    张海霞; 张喜昌

    2016-01-01

    In order to analyze the heat⁃moisture performance of cool polyamide fibers, the basic performance such as fiber fineness unevenness, tensile performance, friction performance, shrinkage rate in boiling water and oil content were tested and analyzed firstly. Based on this, the thermal performance, cooling performance, moisture absorption and liberation performance of cool polyamide fibers were studied, respectively, by differential scanning calorimetry, thermal gravimeter analysis, cooling test, moisture absorption and liberation test. The results show that the fineness unevenness, tensile performance and friction performance of cool polyamide are relatively poor compared with ordinary polyamide fibers, but the shrinkage rate in boiling water and oil content are close to ordinary polyamide fibers. There exist some differences in differential scanning calorimetric curve between cool polyamide fibers and ordinary polyamide fibers. During the process of weaving, dyeing and finishing, the temperature of cool polyamide fibers should be controlled lower than 370 ℃. The cooling performance, moisture absorption and liberation performance of cool polyamide fibers are better than those of ordinary polyamide fibers.%为探讨凉爽锦纶纤维的热湿性能,测试分析了纤维的细度不匀、拉伸性能、摩擦抱合性能、沸水收缩率和含油率等基本性能;在此基础上,通过差热分析、热重分析、降温实验、吸湿实验和放湿实验分别研究了凉爽锦纶纤维的热性能、降温性能和吸放湿性能。结果表明,凉爽锦纶纤维的细度不匀、拉伸性能和摩擦抱合性能比普通锦纶略差,沸水收缩率和含油率与普通锦纶相似;凉爽锦纶纤维的差示扫描量热曲线与普通锦纶存在一定差异,在织造、染整等加工过程中的控制温度应低于370℃;凉爽锦纶纤维的降温性能、吸放湿性能均优于普通锦纶。

  16. 风力机分离式尾缘襟翼气动性能%Aerodynamic performance of discrete trailing edge flaps of wind turbine airfoil

    Institute of Scientific and Technical Information of China (English)

    韩中合; 贾亚雷; 李恒凡; 李秋菊; 刘华新; 朱霄珣

    2014-01-01

    In order to increase the wind capture ability of the wind turbine, many research studies on the lift enhancement method of the wind turbine airfoil have been conducted by scholars at home and abroad. An airfoil with tailing edge flaps has a much higher lift-to-drag ratio than an airfoil without trailing edge flaps. Among all the lift enhancement methods of trailing edge flaps, the structure of the wind turbine airfoil with discrete trailing edge flaps is simple, the cost of production is low, and it can easily achieve variable angle control. But the aerodynamic performance of the wind turbine airfoil with traditional discrete trailing edge flaps has not been comprehensively studied, and gaps between the flaps and the airfoil main body has an influence on the aerodynamic performance of the airfoil. So it is necessary to optimize the gap structure and study the aerodynamic performance of the discrete trailing edge flaps with different deflection angles. Taking a wind turbine airfoil S809 as the research object, the structure of the discrete trailing edge flaps was designed, the chord length was set as 1 000 mm, and the gap between the flap and the main body of airfoil was optimized to make the width of gap an even 1 mm. Then the trailing edge flaps model was established. The flap rotates around the rotate center to form a different flap model at different deflect angles, the deflect angles of the flap varied from 0-16°, and the step size was 2. Mesh generation software Gambit s used to generate a model mesh, and the grids near the trailing edge were refined. After comparing the three kinds of grid number models, the grid independence was verified, and the number of a 148000 grid model for a calculating model was determined. Thek-ω two equation turbulence model of Commercial software FLUENT was used here to calculate the aerodynamic performance of the airfoil S809 without flaps, and the result was compared with the experimental data. The result showed that when the

  17. Advanced Topics in Aerodynamics

    DEFF Research Database (Denmark)

    Filippone, Antonino

    1999-01-01

    "Advanced Topics in Aerodynamics" is a comprehensive electronic guide to aerodynamics,computational fluid dynamics, aeronautics, aerospace propulsion systems, design and relatedtechnology. We report data, tables, graphics, sketches,examples, results, photos, technical andscientific literature...

  18. Aerodynamic Performance and Static Stability and Control of Flat-Top Hypersonic Gliders at Mach Numbers from 0.6 to 18

    Science.gov (United States)

    Syvertson, Clarence A; Gloria, Hermilo R; Sarabia, Michael F

    1958-01-01

    A study is made of aerodynamic performance and static stability and control at hypersonic speeds. In a first part of the study, the effect of interference lift is investigated by tests of asymmetric models having conical fuselages and arrow plan-form wings. The fuselage of the asymmetric model is located entirely beneath the wing and has a semicircular cross section. The fuselage of the symmetric model was centrally located and has a circular cross section. Results are obtained for Mach numbers from 3 to 12 in part by application of the hypersonic similarity rule. These results show a maximum effect of interference on lift-drag ratio occurring at Mach number of 5, the Mach number at which the asymmetric model was designed to exploit favorable lift interference. At this Mach number, the asymmetric model is indicated to have a lift-drag ratio 11 percent higher than the symmetric model and 15 percent higher than the asymmetric model when inverted. These differences decrease to a few percent at a Mach number of 12. In the course of this part of the study, the accuracy to the hypersonic similarity rule applied to wing-body combinations is demonstrated with experimental results. These results indicate that the rule may prove useful for determining the aerodynamic characteristics of slender configurations at Mach numbers higher than those for which test equipment is really available. In a second part of the study, the aerodynamic performance and static stability and control characteristics of a hypersonic glider are investigated in somewhat greater detail. Results for Mach numbers from 3 to 18 for performance and 0.6 to 12 for stability and control are obtained by standard text techniques, by application of the hypersonic stability rule, and/or by use of helium as a test medium. Lift-drag ratios of about 5 for Mach numbers up to 18 are shown to be obtainable. The glider studied is shown to have acceptable longitudinal and directional stability characteristics through the

  19. Frequency thermal response and cooling performance in a microscopic system with a time-dependent perturbation

    Science.gov (United States)

    Beraha, N.; Soba, A.; Carusela, M. F.

    2016-12-01

    Following the nonequilibrium Green's function formalism we study the thermal transport in a composite chain subject to a time-dependent perturbation. The system is formed by two finite linear asymmetric harmonic chains subject to an on-site potential connected together by a time-modulated coupling. The ends of the chains are coupled to two phononic reservoirs at different temperatures. We present the relevant equations used to calculate the heat current along each segment. We find that the system presents different transport regimes according the driving frequency and temperature gradients. One of the regimes corresponds to a heat pump against thermal gradient, thus a characterization of the cooling performance of the device is presented.

  20. Performance investigation of evaporatively-cooled heat exchangers - part one: plain and finned tubes

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, A.; Siren, K.

    2004-07-01

    The performance of two evaporatively cooled heat exchangers is investigated under similar operating conditions of airflow rates and inlet hot water temperatures. The types of the heat exchangers are plain and plate-finned circular tube which occupy the same volume. A substantial increase in heat transfer takes place for the plate-finned tubes. The increase is 92-140% for air velocities from 1.66 to 3.57 m s{sup -1}. The wet-finned surfaces show low fin efficiency compared with dry surfaces. An energy index defined as the ratio of volumetric thermal conductance to air pressure drop per unit length is found to be close for the two heat exchangers. This reveals higher thermal utilisation of the occupied volume by the finned tubes with the same energy index. (orig.)

  1. Dual Nozzle Aerodynamic and Cooling Analysis Study.

    Science.gov (United States)

    1981-02-27

    ALRC Irwin Alber , Consultant Jim Duey, ALRC Joe Hoffman, Purdue University This report presents the Summary, Section I - Introduction, Section II...SCISEARCH. Papers which referred to the works of Korst, Bauer, and Alber were sought in this way. 19 I III, A, Literature Survey (cont.) The second...Point ’rfil Fna! ’w Turnino Annie Wall Anile at Attachrient Pnint hpar I ivPr ’hir r, ,ioz f Nnze Area Datioi P - Primary Nozzle Throa! Radius F Pati

  2. Performance evaluation of three different types of local evaporative cooling pads in greenhouses in Sudan.

    Science.gov (United States)

    Ahmed, Egbal Mohammed; Abaas, Osama; Ahmed, Mohammed; Ismail, Mohd Rodzi

    2011-01-01

    This study was conducted in Date Palm Technology Company Limited, Shambat, Khartoum State. To evaluate performance of three types of evaporative cooling pads for greenhouses (celdek pads, straw pads and sliced wood pads), as compared to the conditions outside the greenhouses (control), for pads. Performance evaluation includes environmental parameters (temperature and relative humidity at 8 am, 1 pm and 6 pm) and crop parameters (length and stem diameter, leaves number and width, fruit length and diameter, fruit weight and dry matter and yield). The results obtained for the temperature at 8 am showed that there was no significant difference (0.05) inside the greenhouses, while a high significant difference between the conditions inside and outside of the greenhouses was found. Significant differences were found at 1 pm and 6 pm between all treatments as compared to the conditions outside the greenhouses, and the results obtained for relative humidity showed high significant differences at 8 am and 1 pm inside the greenhouses and between inside and outside the greenhouse, respectively, while there was no significant difference at 6 pm inside the greenhouses and between inside and outside the greenhouses. On the other hand, the results obtained for crop parameters showed that there were significant differences between all parameters inside the greenhouses and outside the greenhouses; however, the greenhouses with sliced wood pads gave the highest yield and the greenhouses with straw pads gave the least and conditions outside gave the lowest. This study indicated that the sliced wood pads are better than the other evaporative cooling pads.

  3. Thermal Performance for Wet Cooling Tower with Different Layout Patterns of Fillings under Typical Crosswind Conditions

    Directory of Open Access Journals (Sweden)

    Ming Gao

    2017-01-01

    Full Text Available A thermal-state model experimental study was performed in lab to investigate the thermal performance of a wet cooling tower with different kinds of filling layout patterns under windless and 0.4 m/s crosswind conditions. In this paper, the contrast analysis was focused on comparing a uniform layout pattern and one kind of optimal non-uniform layout pattern when the environmental crosswind speed is 0 m/s and 0.4 m/s. The experimental results proved that under windless conditions, the heat transfer coefficient and total heat rejection of circulating water for the optimal non-uniform layout pattern can enhance by approximately 40% and 28%, respectively, compared with the uniform layout pattern. It was also discovered that the optimal non-uniform pattern can dramatically relieve the influence of crosswind on the thermal performance of the tower when the crosswind speed is equal to 0.4 m/s. For the uniform layout pattern, the heat transfer coefficient under 0.4 m/s crosswind conditions decreased by 9.5% compared with the windless conditions, while that value lowered only by 2.0% for the optimal non-uniform layout pattern. It has been demonstrated that the optimal non-uniform layout pattern has the better thermal performance under 0.4 m/s crosswind condition.

  4. Computational Analysis of Droplet Mass and Size Effect on Mist/Air Impingement Cooling Performance

    Directory of Open Access Journals (Sweden)

    Zhenglei Yu

    2013-01-01

    Full Text Available Impingement cooling has been widely employed to cool gas turbine hot components such as combustor liners, combustor transition pieces, turbine vanes, and blades. A promising technology is proposed to enhance impingement cooling with water droplets injection. However, previous studies were conducted on blade shower head film cooling, and less attention was given to the transition piece cooling. As a continuous effort to develop a realistic mist impingement cooling scheme, this paper focuses on simulating mist impingement cooling under typical gas turbine operating conditions of high temperature and pressure in a double chamber model. Furthermore, the paper presents the effect of cooling effectiveness by changing the mass and size of the droplets. Based on the heat-mass transfer analogy, the results of these experiments prove that the mass of 3E – 3 kg/s droplets with diameters of 5–35 μm could enhance 90% cooling effectiveness and reduce 122 K of wall temperature. The results of this paper can provide guidance for corresponding experiments and serve as the qualification reference for future more complicated studies with convex surface cooling.

  5. Rotor/body aerodynamic interactions

    Science.gov (United States)

    Betzina, M. D.; Smith, C. A.; Shinoda, P.

    1985-01-01

    A wind tunnel investigation was conducted in which independent, steady state aerodynamic forces and moments were measured on a 2.24 m diam. two bladed helicopter rotor and on several different bodies. The mutual interaction effects for variations in velocity, thrust, tip-path-plane angle of attack, body angle of attack, rotor/body position, and body geometry were determined. The results show that the body longitudinal aerodynamic characteristics are significantly affected by the presence of a rotor and hub, and that the hub interference may be a major part of such interaction. The effects of the body on the rotor performance are presented.

  6. Passive Cooling of Body Armor

    Science.gov (United States)

    Holtz, Ronald; Matic, Peter; Mott, David

    2013-03-01

    Warfighter performance can be adversely affected by heat load and weight of equipment. Current tactical vest designs are good insulators and lack ventilation, thus do not provide effective management of metabolic heat generated. NRL has undertaken a systematic study of tactical vest thermal management, leading to physics-based strategies that provide improved cooling without undesirable consequences such as added weight, added electrical power requirements, or compromised protection. The approach is based on evaporative cooling of sweat produced by the wearer of the vest, in an air flow provided by ambient wind or ambulatory motion of the wearer. Using an approach including thermodynamic analysis, computational fluid dynamics modeling, air flow measurements of model ventilated vest architectures, and studies of the influence of fabric aerodynamic drag characteristics, materials and geometry were identified that optimize passive cooling of tactical vests. Specific architectural features of the vest design allow for optimal ventilation patterns, and selection of fabrics for vest construction optimize evaporation rates while reducing air flow resistance. Cooling rates consistent with the theoretical and modeling predictions were verified experimentally for 3D mockups.

  7. Isothermal Adsorption Measurement for the Development of High Performance Solid Sorption Cooling System

    Science.gov (United States)

    Saha, Bidyut Baran; Koyama, Shigeru; Alam, K. C. Amanul; Hamamoto, Yoshinori; Akisawa, Atsushi; Kashiwagi, Takao; Ng, Kim Choon; Chua, Hui Tong

    Interest in low-grade thermal heat powered solid sorption system using natural refrigerants has been increased. However, the drawbacks of these adsorption systems are their poor performance. The objective of this paper is to improve the performance of thermally powered adsorption cooling system by selecting new adsorbent-refrigerant pairs. Adsorption capacity of adsorbent-refrigerant pair depends on the thermophysical properties (pore size, pore volume and pore diameter) of adsorbent and isothermal characteristics of the adsorbent-refrigerant pair. In this paper, the thermophysical properties of three types of silica gels and three types of pitch based activated carbon fibers are determined from the nitrogen adsorption isotherms. The standard nitrogen gas adsorption/desorption measurements on various adsorbents at liquid nitrogen of temperature 77.4 K were performed. Surface area of each adsorbent was determined by the Brunauer, Emmett and Teller (BET) plot of nitrogen adsorption data. Pore size distribution was measured by the Horvath and Kawazoe (HK) method. Adsorption/desorption isotherm results showed that all three carbon fibers have no hysteresis and had better adsorption capacity in comparison with those of silica gels.

  8. Theoretical study on volatile organic compound removal and energy performance of a novel heat pump assisted solid desiccant cooling system

    DEFF Research Database (Denmark)

    Nie, Jinzhe; Fang, Lei; Zhang, Ge

    2015-01-01

    A theoretical model was established for predicting the volatile organic compound (VOC) removal and energy performance of a novel heat pump assisted solid desiccant cooling system (HP-SDC). The HP-SDC was proposed based on the combination of desiccant rotor with heat pump, and was designed...... for cooling, dehumidification and indoor air cleaning in normal office, commercial or residential buildings. The desiccant rotor was used for dehumidification and indoor air cleaning; the heat pump provided sensible cooling and regeneration heat for the desiccant rotor. The theoretical model consisted of two...... sub-models. One sub-model was used to simulate the heat, moisture and VOC transfer in the desiccant rotor; the other sub-model was used to predict the energy performance of the heat pump. Combining the two sub-models, the energy performance and VOC removal effect of the HP-SDC could be simulated...

  9. Experiment Investigation on Electrical and Thermal Performances of a Semitransparent Photovoltaic/Thermal System with Water Cooling

    Directory of Open Access Journals (Sweden)

    Guiqiang Li

    2014-01-01

    Full Text Available Different from the semitransparent building integrated photovoltaic/thermal (BIPV/T system with air cooling, the semitransparent BIPV/T system with water cooling is rare, especially based on the silicon solar cells. In this paper, a semitransparent photovoltaic/thermal system (SPV/T with water cooling was set up, which not only would provide the electrical power and hot water, but also could attain the natural illumination for the building. The PV efficiency, thermal efficiency, and exergy analysis were all adopted to illustrate the performance of SPV/T system. The results showed that the PV efficiency and the thermal efficiency were about 11.5% and 39.5%, respectively, on the typical sunny day. Furthermore, the PV and thermal efficiencies fit curves were made to demonstrate the SPV/T performance more comprehensively. The performance analysis indicated that the SPV/T system has a good application prospect for building.

  10. Aerodynamic design via control theory

    Science.gov (United States)

    Jameson, Antony

    1988-01-01

    The question of how to modify aerodynamic design in order to improve performance is addressed. Representative examples are given to demonstrate the computational feasibility of using control theory for such a purpose. An introduction and historical survey of the subject is included.

  11. Effect of façade systems on the performance of cooling ceilings: In situ measurements

    Directory of Open Access Journals (Sweden)

    Katharina Eder

    2015-03-01

    Full Text Available This article presents an innovative façade system designed to increase the thermal comfort inside an office room and to enhance the cooling capacity of the suspended cooling ceiling. A series of measurements is conducted in an existing office building with different façade systems (i.e., a combination of glazing and shading. An innovative façade system is developed based on this intensive set of measurements. The new system enhances the thermal comfort and cooling capacity of the suspended cooling ceiling. The main usage of the new system is the refurbishment and improvement of existing façade systems.

  12. Interim Report: Air-Cooled Condensers for Next Generation Geothermal Power Plants Improved Binary Cycle Performance

    Energy Technology Data Exchange (ETDEWEB)

    Daniel S. Wendt; Greg L. Mines

    2010-09-01

    As geothermal resources that are more expensive to develop are utilized for power generation, there will be increased incentive to use more efficient power plants. This is expected to be the case with Enhanced Geothermal System (EGS) resources. These resources will likely require wells drilled to depths greater than encountered with hydrothermal resources, and will have the added costs for stimulation to create the subsurface reservoir. It is postulated that plants generating power from these resources will likely utilize the binary cycle technology where heat is rejected sensibly to the ambient. The consumptive use of a portion of the produced geothermal fluid for evaporative heat rejection in the conventional flash-steam conversion cycle is likely to preclude its use with EGS resources. This will be especially true in those areas where there is a high demand for finite supplies of water. Though they have no consumptive use of water, using air-cooling systems for heat rejection has disadvantages. These systems have higher capital costs, reduced power output (heat is rejected at the higher dry-bulb temperature), increased parasitics (fan power), and greater variability in power generation on both a diurnal and annual basis (larger variation in the dry-bulb temperature). This is an interim report for the task ‘Air-Cooled Condensers in Next- Generation Conversion Systems’. The work performed was specifically aimed at a plant that uses commercially available binary cycle technologies with an EGS resource. Concepts were evaluated that have the potential to increase performance, lower cost, or mitigate the adverse effects of off-design operation. The impact on both cost and performance were determined for the concepts considered, and the scenarios identified where a particular concept is best suited. Most, but not all, of the concepts evaluated are associated with the rejection of heat. This report specifically addresses three of the concepts evaluated: the use of

  13. Simulation and performance enhancement of the air cooling system in a DC/AC power converter station

    Energy Technology Data Exchange (ETDEWEB)

    Lozowy, R.; El-Shaboury, A.; Soliman, H.; Ormiston, S. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Mechanical and Manufacturing Engineering

    2010-07-01

    This study analyzed the flow structure and heat transfer in a large 3-dimensional domain with turbulence, mixed convection, an impinging jet, and flow over heated blocks. The objective was to better understand turbulent mixed-convection cooling of heat-generating bodies in 3-dimensional enclosures, which is important to industry. The cooling of 2 thyristor valve halls was simulated. Each valve hall housed 3 towers that contained electronics used in DC/AC power conversion. The simulation results included the magnitudes of the net air flows for all the inter-block gaps and the maximum temperature in each gap. A parametric study was also performed to investigate the effects of the air inlet location, size and aspect ratio. The effects of the air injection angle on cooling effectiveness was also examined. The study showed that for fixed inlet mass flow rate, significant improvement in the cooling effectiveness can be obtained by changing the injection angle of the inlet air jet, the location of the inlet grill, or the size of the inlet grill. It was concluded that these study results may be relevant to other applications, such as the design of power transformers, the design of cooling systems for spent nuclear fuel and computer server cooling racks. 13 refs., 12 figs.

  14. Effect of Target Configuration on the Neutronic Performance of the Gas-Cooled ADS

    CERN Document Server

    Biss, K; Shetty, N; Nabbi, R

    2013-01-01

    With the utilization of nuclear energy transuranic elements like Pu, Am and Cm are produced causing high, long term radioactivity and radio toxicity, respectively. To reduce the radiological impact on the environment and to the repository Partitioning and Transmutation is considered as an efficient way. In this respect comprehensive research works are performed at different research institutes worldwide. The results show that the transmutation of TRU is achieved with fast neutrons due to the higher fission probability. Based on Accelerator Driven Systems (ADS) those neutrons are used in a particular system, in which mainly liquid metal eutectic (lead bismuth) is used as coolant. The neutronic performance of an ADS system based on gas cooling was studied in this work by using the simulation tool MCNPX. The usage of the Monte-Carlo method in MCNPX allows the simulation of the physical processes in a 3D-model of the core. In dependence of the spallation target material and design several parameters like the mult...

  15. Performance predictions of a focused ion beam from a laser cooled and compressed atomic beam

    Energy Technology Data Exchange (ETDEWEB)

    Haaf, G. ten; Wouters, S. H. W.; Vredenbregt, E. J. D.; Mutsaers, P. H. A. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Geer, S. B. van der [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)

    2014-12-28

    Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here, we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of, amongst others, the flux density of the atomic beam, the temperature of this beam, and the total current. At low currents (I < 10 pA), the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents, this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model was verified with particle tracing simulations of a complete focused ion beam setup. A genetic algorithm was used to find the optimum acceleration electric field as a function of the current. At low currents, the result agrees well with the analytical model, while at higher currents, the spot sizes found are even lower due to effects that are not taken into account in the analytical model.

  16. Performance predictions of a focused ion beam based on laser cooling

    CERN Document Server

    Haaf, G ten; van der Geer, S B; Vredenbregt, E J D; Mutsaers, P H A

    2014-01-01

    Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of amongst others the flux density of the atomic beam, the temperature of this beam and the total current. At low currents (I<10 pA) the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model w...

  17. Effect of Material Inhomogeneity on Thermal Performance of a Rheocast Aluminum Heatsink for Electronics Cooling

    Science.gov (United States)

    Payandeh, M.; Belov, I.; Jarfors, A. E. W.; Wessén, M.

    2016-06-01

    The relation between microstructural inhomogeneity and thermal conductivity of a rheocast component manufactured from two different aluminum alloys was investigated. The formation of two different primary α-Al particles was observed and related to multistage solidification process during slurry preparation and die cavity filling process. The microstructural inhomogeneity of the component was quantified as the fraction of α 1-Al particles in the primary Al phase. A high fraction of coarse solute-lean α 1-Al particles in the primary Al phase caused a higher thermal conductivity of the component in the near-to-gate region. A variation in thermal conductivity through the rheocast component of 10% was discovered. The effect of an inhomogeneous temperature-dependent thermal conductivity on the thermal performance of a large rheocast heatsink for electronics cooling in an operation environment was studied by means of simulation. Design guidelines were developed to account for the thermal performance of heatsinks with inhomogeneous thermal conductivity, as caused by the rheocasting process. Under the modeling assumptions, the simulation results showed over 2.5% improvement in heatsink thermal resistance when the higher conductivity near-to-gate region was located at the top of the heatsink. Assuming homogeneous thermo-physical properties in a rheocast heatsink may lead to greater than 3.5% error in the estimation of maximum thermal resistance of the heatsink. The variation in thermal conductivity within a large rheocast heatsink was found to be important for obtaining of a robust component design.

  18. Performance of vegetable oils as a cooling medium in comparison to a standard mineral oil

    Science.gov (United States)

    Totten, G. E.; Tensi, H. M.; Lainer, K.

    1999-08-01

    Immersion quenching is the most widely used quenching technique today and is usually one of the last steps in heat treat processing. Improper hardening to incorrect cooling is generally a great loss and causes a great percentage of manufacturing costs. To avoid a failure in cooling, researchers are committed to describing the cooling effect as precisely as possible. The cooling of immersion cooled workpieces or probes is generally characterized by the process of wetting. Evaporable fluids exhibit the three well known stages of cooling: vapor blanket stage, boiling stage, and convective heat transfer. Therefore cooling behavior is influenced by a wide variety and depends on a number of parameters, that is, type of quenchant used, bath temperature, rate of agitation, and the physical and chemical properties of the quenched parts. Environmental pollution has caused the search for new products in har dening and shock cooling of steels. The use of soybean oils as quenching fluids is new, and compared with standard mineral oils, there are many advantages mainly concerning the environment and the health of workers.

  19. Effect of floor cooling on farrowing sow and litter performance: Field experiment under Dutch conditions

    NARCIS (Netherlands)

    Wagenberg, van A.V.; Peet-Schwering, van der C.M.C.; Binnendijk, G.P.; Claessen, P.J.P.W.

    2006-01-01

    Lactating sows generally have problems dissipating their body heat to the environment. Cooling the floor under the sow¿s shoulder, called the cool-sow system, is a method to increase body heat removal by conduction, thereby contributing to the thermal comfort of the sow. In this study, the effect of

  20. A Collaborative Analysis Tool for Integrated Hypersonic Aerodynamics, Thermal Protection Systems, and RBCC Engine Performance for Single Stage to Orbit Vehicles

    Science.gov (United States)

    Stanley, Thomas Troy; Alexander, Reginald; Landrum, Brian

    2000-01-01

    engine model. HYFIM performs the aerodynamic analysis of forebodies and inlet characteristics of RBCC powered SSTO launch vehicles. HYFIM is applicable to the analysis of the ramjet/scramjet engine operations modes (Mach 3-12), and provides estimates of parameters such as air capture area, shock-on-lip Mach number, design Mach number, compression ratio, etc., based on a basic geometry routine for modeling axisymmetric cones, 2-D wedge geometries. HYFIM also estimates the variation of shock layer properties normal to the forebody surface. The thermal protection system (TPS) is directly linked to determination of the vehicle moldline and the shaping of the trajectory. Thermal protection systems to maintain the structural integrity of the vehicle must be able to mitigate the heat transfer to the structure and be lightweight. Herein lies the interdependency, in that as the vehicle's speed increases, the TPS requirements are increased. And as TPS masses increase the effect on the propulsion system and all other systems is compounded. The need to analyze vehicle forebody and engine inlet is critical to be able to design the RBCC vehicle. To adequately determine insulation masses for an RBCC vehicle, the hypersonic aerodynamic environment and aeroheating loads must be calculated and the TPS thicknesses must be calculated for the entire vehicle. To accomplish this an ascent or reentry trajectory is obtained using the computer code Program to Optimize Simulated Trajectories (POST). The trajectory is then used to calculate the convective heat rates on several locations on the vehicles using the Miniature Version of the JA70 Aerodynamic Heating Computer Program (MINIVER). Once the heat rates are defined for each body point on the vehicle, then insulation thicknesses that are required to maintain the vehicle within structural limits are calculated using Systems Improved Numerical Differencing Analyzer (SINDA) models. If the TPS masses are too heavy for the performance of the vehicle

  1. Meta-analysis of the effects of microclimate cooling systems on human performance under thermal stressful environments: potential applications to occupational workers.

    Science.gov (United States)

    Chan, Albert P C; Song, Wenfang; Yang, Yang

    2015-01-01

    This study aims to determine the appropriate microclimate cooling systems (MCSs) to reduce heat stress and improve human performance of occupational workers and their practicality in the occupational field. Meta-analysis was employed to summarize, analyze, and compare the effects of various MCSs on human performance with corresponding physiological and psychological responses, thereby providing solid suggestions for selecting suitable MCSs for occupational workers. Wearing MCSs significantly attenuated the increases in core temperature (-0.34 °C/h) and sweating rate (-0.30 L/h), and significantly improved human performance (+29.9%, effect size [EFS] = 1.1) compared with no cooling condition (CON). Cold air-cooled garments (ACG-Cs; +106.2%, EFS = 2.32) exhibited greater effects on improving human performance among various microclimate cooling garments (MCGs), followed by liquid cooling garments (LCGs; +68.1%, EFS = 1.86) and hybrid cooling garment combining air and liquid cooling (HBCG-AL; +59.1%, EFS=3.38), natural air-cooled garments (ACG-Ns; +39.9%, EFS = 1.12), and phase change material cooling garments (PCMCGs; +19.5%, EFS = 1.2). Performance improvement was observed to be positively and linearly correlated to the differences of core temperature increase rate (r = 0.65, p workers do not move frequently, whereas ACG-Ns and PCMCGs are more applicable for the majority of occupational workers. Further enhancement of the cooling efficiency of these two cooling strategies should be initiated.

  2. Theoretical investigations on improving performance of cooling systems for fuel cell vehicles; Theoretische Untersuchungen zur Kuehlleistungssteigerung durch innovative Kuehlsysteme fuer Brennstoffzellen-Elektrofahrzeuge

    Energy Technology Data Exchange (ETDEWEB)

    Reichler, Mark

    2008-04-01

    In this work theoretical investigations are carried out for cooling systems, which are used in fuel cell vehicles. This work focuses mainly on the capability of increasing the heat rejection rate by using new alternative cooling systems and by improving the conventional cooling system. Fuel cell vehicles have a higher demand of heat rejection to the ambient than comparable vehicles with combustion engine. The performance of conventional liquid cooling systems, especially at high loads and high ambient temperatures, is often not sufficient anymore. Hence, cooling systems with improved performance are necessary for fuel cell vehicles. The investigations in this work are based on DaimlerChrysler's ''A-Class'' having a PEM-Fuel Cell system integrated. Specific computational models are developed for radiators and condensers to evaluate the performance of different cooling concepts. The models are validated with experimental data. Based on an intensive investigation in the open literature the state of the art of cooling systems for fuel cell vehicles is depicted. Furthermore new cooling concepts as an alternative to the liquid cooling system are presented. The method of cooling the fuel cell by using two-phase transition shows the greatest capability to increase the cooling performance. Hence, this concept is investigated in detail. Two different concepts with three different refrigerants (R113, R245fa und R236fa) are analyzed. Cooling performance of this concept shows improvement of 18.2 up to 32.6 % compared to the conventional liquid cooling system. Thus, a two phase cooling system represents an alternative cooling system for fuel cell vehicles, which should be closer investigated by experiments. (orig.)

  3. Aerodynamics of wind turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design...... Turbines (VAWT). Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method...... is also covered, as are eigenmodes and the dynamic behaviour of a turbine. The book describes the effects of the dynamics and how this can be modelled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Furthermore, it examines how to calculate...

  4. Design and expected performance of the MICE demonstration of ionization cooling arXiv

    CERN Document Server

    Bogomilov, M.; Vankova-Kirilova, G.; Song, Y.; Tang, J.; Li, Z.; Bertoni, R.; Bonesini, M.; Chignoli, F.; Mazza, R.; Palladino, V.; de Bari, A.; Cecchet, G.; Orestano, D.; Tortora, L.; Kuno, Y.; Ishimoto, S.; Filthaut, F.; Jokovic, D.; Maletic, D.; Savic, M.; Hansen, O.M.; Ramberger, S.; Vretenar, M.; Asfandiyarov, R.; Blondel, A.; Drielsma, F.; Karadzhov, Y.; Charnley, G.; Collomb, N.; Gallagher, A.; Grant, A.; Griffiths, S.; Hartnett, T.; Martlew, B.; Moss, A.; Muir, A.; Mullacrane, I.; Oates, A.; Owens, P.; Stokes, G.; Tucker, M.; Warburton, P.; White, C.; Adams, D.; Anderson, R.J.; Barclay, P.; Bayliss, V.; Boehm, J.; Bradshaw, T.W.; Courthold, M.; Dumbell, K.; Francis, V.; Fry, L.; Hayler, T.; Hills, M.; Lintern, A.; Macwaters, C.; Nichols, A.; Preece, R.; Ricciardi, S.; Rogers, C.; Stanley, T.; Tarrant, J.; Wilson, A.; Watson, S.; Bayes, R.; Nugent, J.C.; Soler, F.J.P.; Gamet, R.; Barber, G.; Blackmore, V.J.; Colling, D.; Dobbs, A.; Dornan, P.; Hunt, C.; Kurup, A.; Lagrange, J.B.; Long, K.; Martyniak, J.; Middleton, S.; Pasternak, J.; Uchida, M.A.; Cobb, J.H.; Lau, W.; Booth, C.N.; Hodgson, P.; Langlands, J.; Overton, E.; Robinson, M.; Smith, P.J.; Wilbur, S.; Dick, A.J.; Ronald, K.; Whyte, C.G.; Young, A.R.; Boyd, S.; Franchini, P.; Greis, J.R.; Pidcott, C.; Taylor, I.; Gardener, R.B.S.; Kyberd, P.; Nebrensky, J.J.; Palmer, M.; Witte, H.; Bross, A.D.; Bowring, D.; Liu, A.; Neuffer, D.; Popovic, M.; Rubinov, P.; DeMello, A.; Gourlay, S.; Li, D.; Prestemon, S.; Virostek, S.; Zisman, M.; Freemire, B.; Hanlet, P.; Kaplan, D.M.; Mohayai, T.A.; Rajaram, D.; Snopok, P.; Suezaki, V.; Torun, Y.; Onel, Y.; Cremaldi, L.M.; Sanders, D.A.; Summers, D.J.; Hanson, G.G.; Heidt, C.

    Muon beams of low emittance provide the basis for the intense, well-characterised neutrino beams necessary to elucidate the physics of flavour at a neutrino factory and to provide lepton-antilepton collisions at energies of up to several TeV at a muon collider. The international Muon Ionization Cooling Experiment (MICE) aims to demonstrate ionization cooling, the technique by which it is proposed to reduce the phase-space volume occupied by the muon beam at such facilities. In an ionization-cooling channel, the muon beam passes through a material in which it loses energy. The energy lost is then replaced using RF cavities. The combined effect of energy loss and re-acceleration is to reduce the transverse emittance of the beam (transverse cooling). A major revision of the scope of the project was carried out over the summer of 2014. The revised experiment can deliver a demonstration of ionization cooling. The design of the cooling demonstration experiment will be described together with its predicted cooling p...

  5. Data Mining of the Thermal Performance of Cool-Pipes in Massive Concrete via In Situ Monitoring

    Directory of Open Access Journals (Sweden)

    Zheng Zuo

    2014-01-01

    Full Text Available Embedded cool-pipes are very important for massive concrete because their cooling effect can effectively avoid thermal cracks. In this study, a data mining approach to analyzing the thermal performance of cool-pipes via in situ monitoring is proposed. Delicate monitoring program is applied in a high arch dam project that provides a good and mass data source. The factors and relations related to the thermal performance of cool-pipes are obtained in a built theory thermal model. The supporting vector machine (SVM technology is applied to mine the data. The thermal performances of iron pipes and high-density polyethylene (HDPE pipes are compared. The data mining result shows that iron pipe has a better heat removal performance when flow rate is lower than 50 L/min. It has revealed that a turning flow rate exists for iron pipe which is 80 L/min. The prediction and classification results obtained from the data mining model agree well with the monitored data, which illustrates the validness of the approach.

  6. Performance characteristics of two-phase-flow turbo-expanders used in water-cooled chillers

    Energy Technology Data Exchange (ETDEWEB)

    Brasz, J.J. [United Technologies Carrier, New York, NY (United States)

    1999-07-01

    Use of two-phase-flow throttle loss recovery devices in water-cooled chillers requires satisfactory part-load operation. This paper describes the results of two-phase-flow impulse turbine testing and the data reduction of the test results into a two-phase-flow turbine off-design performance model. It was found that the main parameter controlling the efficiency of two-phase-flow turbine is the ratio of the nozzle spouting velocity to the rotor speed. The turbine mass flow rate is mainly controlled by inlet subcooling of the entering liquid. The strong sensitivity of turbine mass flow rate on inlet subcooling allows the use of a conventional float valve upstream of the turbine as an effective means of controlling the turbine during part-load operation. For a well-designed two-phase-flow turbine, nozzle spouting velocity and therefore turbine efficiency is hardly affected by the amount of inlet subcooling. Also, capacity can be substantially reduced by a reduction in the amount of inlet subcooling entering the turbine nozzles. Hence, turbine part-load efficiency equals its full-load efficiency over a wide range of flow rates using this control concept. (Author)

  7. Heat Transfer Characteristics and Performance of a Spirally Coiled Heat Exchanger under Sensible Cooling Conditions

    Science.gov (United States)

    Wongwises, Somchai; Naphon, Paisarn

    In the present study, new experimental data on the heat transfer characteristics and the performance of a spirally coiled heat exchanger under sensible cooling conditions is presented. The spiral-coil heat exchanger consists of a steel shell and a spirally coiled tube unit. The spiral-coil unit consists of six layers of concentric spirally coiled tubes. Each tube is fabricated by bending a 9.27mm diameter straight copper tube into a spiral-coil of five turns. The innermost and outermost diameters of each spiral-coil are 67.7 and 227.6mm, respectively. Air and water are used as working fluids in shell side and tube side, respectively. A mathematical model based on the conservation of energy is developed to determine the heat transfer characteristics. There is a reasonable agreement between the results obtained from the experiment and those obtained from the model and a good agreement for the high air mass flow rate region. The results obtained from the parametric study are also discussed.

  8. Comparison of Oxidation Stability and Quenchant Cooling Curve Performance of Soybean Oil and Palm Oil

    Science.gov (United States)

    Said, Diego; Belinato, Gabriela; Sarmiento, Gustavo S.; Otero, Rosa L. Simencio; Totten, George E.; Gastón, Analía; Canale, Lauralice C. F.

    2013-07-01

    The potential use of vegetable oil-derived industrial oils continues to be of great interest because vegetable oils are relatively non-toxic, biodegradable, and they are a renewable basestock alternative to petroleum oil. However, the fatty ester components containing conjugated double bonds of the triglyceride structure of vegetable oils typically produce considerably poorer thermal-oxidative stability than that achievable with petroleum basestocks under typical use conditions. Typically, these conditions involve furnace loads of hot steel (850 °C), which are rapidly immersed and cooled to bath temperatures of approximately 50-60 °C. This is especially true when a vegetable oil is held in an open tank with agitation and exposed to air at elevated temperatures for extended periods of time (months or years). This paper will describe the thermal-oxidative stability and quenching performance of soybean oil and palm oil and the resulting impact on the heat transfer coefficient. These results are compared to typical fully formulated, commercially available accelerated (fast) and an unaccelerated (slow) petroleum oil-based quenchants.

  9. A climatology of formation conditions for aerodynamic contrails

    Directory of Open Access Journals (Sweden)

    K. Gierens

    2013-06-01

    Full Text Available Aerodynamic contrails are defined in this paper as line shaped ice clouds caused by aerodynamically triggered cooling over the wings of an aircraft in cruise which become visible immediately at the trailing edge of the wing or close to it. Effects at low altitudes like condensation to liquid droplets and their potential heterogeneous freezing are excluded from our definition. We study atmospheric conditions that allow formation of aerodynamic contrails. These conditions are stated and then applied to atmospheric data, first to a special case where an aerodynamic contrail was actually observed and then to a full year of global reanalysis data. We show where, when (seasonal variation, and how frequently (probability aerodynamic contrails can form, and how this relates to actual patterns of air traffic. We study the formation of persistent aerodynamic contrails as well. Finally we check whether aerodynamic and exhaust contrails can coexist in the atmosphere. We show that visible aerodynamic contrails are possible only in an altitude range between roughly 540 and 250 hPa, and that the ambient temperature is the most important parameter, not the relative humidity. Finally we give an argument for our believe that currently aerodynamic contrails have a much smaller climate effect than exhaust contrails, which may however change in future with more air traffic in the tropics.

  10. Warm Up and Cool Down: Reduce Risk of Injury and Improve Athletic Performance

    Science.gov (United States)

    ... exercise, but more research is needed. Although there's controversy about whether warming up and cooling down can ... mayoclinic.org/healthy-lifestyle/fitness/in-depth/exercise/art-20045517 . Mayo Clinic Footer Legal Conditions and Terms ...

  11. Energy Performance of Water-based and Air-based Cooling Systems in Plus-energy Housing

    DEFF Research Database (Denmark)

    Andersen, Mads E.; Schøtt, Jacob; Kazanci, Ongun Berk

    2016-01-01

    Energy use in buildings accounts for a large part of the energy use globally and as a result of this, international building energy performance directives are becoming stricter. This trend has led to the development of zero-energy and plus-energy buildings. Some of these developments have led...... achieved and cooling might be needed even in residential buildings. This paper focuses on the cooling operation of a detached, single-family house, which was designed as a plus-energy house in Denmark. The simulation model of the house was created in IDA ICE and it was validated with measurement data...... energy use reductions. The coupling of radiant floor with the ground enables to obtain “free” cooling, although the brine pump power should be kept to a minimum to fully take advantage of this solution. By implementing a ground heat exchanger instead of the heat pump and use the crawl-space air as intake...

  12. An experimental investigation on air-side performances of finned tube heat exchangers for indirect air-cooling tower

    Directory of Open Access Journals (Sweden)

    Du Xueping

    2014-01-01

    Full Text Available A tremendous quantity of water can be saved if the air cooling system is used, comparing with the ordinary water-cooling technology. In this study, two kinds of finned tube heat exchangers in an indirect air-cooling tower are experimentally studied, which are a plain finned oval-tube heat exchanger and a wavy-finned flat-tube heat exchanger in a cross flow of air. Four different air inlet angles (90°, 60 °, 45°, and 30° are tested separately to obtain the heat transfer and resistance performance. Then the air-side experimental correlations of the Nusselt number and friction factor are acquired. The comprehensive heat transfer performances for two finned tube heat exchangers under four air inlet angles are compared. For the plain finned oval-tube heat exchanger, the vertical angle (90° has the worst performance while 45° and 30° has the best performance at small ReDc and at large ReDc, respectively. For the wavy-finned flat-tube heat exchanger, the worst performance occurred at 60°, while the best performance occurred at 45° and 90° at small ReDc and at large ReDc, respectively. From the comparative results, it can be found that the air inlet angle has completely different effects on the comprehensive heat transfer performance for the heat exchangers with different structures.

  13. Unsteady High Turbulence Effects on Turbine Blade Film Cooling Heat Transfer Performance Using a Transient Liquid Crystal Technique

    Science.gov (United States)

    Han, J. C.; Ekkad, S. V.; Du, H.; Teng, S.

    2000-01-01

    Unsteady wake effect, with and without trailing edge ejection, on detailed heat transfer coefficient and film cooling effectiveness distributions is presented for a downstream film-cooled gas turbine blade. Tests were performed on a five-blade linear cascade at an exit Reynolds number of 5.3 x 10(exp 5). Upstream unsteady wakes were simulated using a spoke-wheel type wake generator. Coolant blowing ratio was varied from 0.4 to 1.2; air and CO2 were used as coolants to simulate different density ratios. Surface heat transfer and film effectiveness distributions were obtained using a transient liquid crystal technique; coolant temperature profiles were determined with a cold wire technique. Results show that Nusselt numbers for a film cooled blade are much higher compared to a blade without film injection. Unsteady wake slightly enhances Nusselt numbers but significantly reduces film effectiveness versus no wake cases. Nusselt numbers increase only slic,htly but film cooling, effectiveness increases significantly with increasing, blowing ratio. Higher density coolant (CO2) provides higher effectiveness at higher blowing ratios (M = 1.2) whereas lower density coolant (Air) provides higher 0 effectiveness at lower blowing ratios (M = 0.8). Trailing edge ejection generally has more effect on film effectiveness than on the heat transfer, typically reducing film effectiveness and enhancing heat transfer. Similar data is also presented for a film cooled cylindrical leading edge model.

  14. 3-Dimensional numerical study of cooling performance of a heat sink with air-water flow through mini-channel

    Science.gov (United States)

    Majumder, Sambit; Majumder, Abhik; Bhaumik, Swapan

    2016-07-01

    The present microelectronics market demands devices with high power dissipation capabilities having enhanced cooling per unit area. The drive for miniaturizing the devices to even micro level dimensions is shooting up the applied heat flux on such devices, resulting in complexity in heat transfer and cooling management. In this paper, a method of CPU processor cooling is introduced where active and passive cooling techniques are incorporated simultaneously. A heat sink consisting of fins is designed, where water flows internally through the mini-channel fins and air flows externally. Three dimensional numerical simulations are performed for large set of Reynolds number in laminar region using finite volume method for both developing flows. The dimensions of mini-channel fins are varied for several aspect ratios such as 1, 1.33, 2 and 4. Constant temperature (T) boundary condition is applied at heat sink base. Channel fluid temperature, pressure drop are analyzed to obtain best cooling option in the present study. It has been observed that as the aspect ratio of the channel decreases Nusselt number decreases while pressure drop increases. However, Nusselt number increases with increase in Reynolds number.

  15. INVESTIGATION OF THE PERFORMANCE OF AN ATMOSPHERIC COOLING TOWER USING FRESH AND SALTED WATER

    OpenAIRE

    A. Haddad

    2012-01-01

    Cooling towers are extensively used to evacuate large quantities of heat at modest temperatures through a change of phase of the flowing cooling fluid. Based on this classical principle, the present study investigates the influence of salty water on the heat exchange produced. For that purpose, experiments are carried out using fresh and salty water. Furthermore, a comparison with the results produced through an approach involving the solution of energy equation involving the flow...

  16. Numerical Simulation of Planform Geometry Effect on Parafoil Aerodynamic Performance%翼伞平面形状对翼伞气动性能的影响

    Institute of Scientific and Technical Information of China (English)

    朱旭; 曹义华

    2011-01-01

    3D steady flow fields of parafoils with cells, an aspect ratio of 3.0 , and different planform geometries are numerically simulated by using a computational fluid dynamics (CFD) technique to study the planform geometry effect on parafoil aerodynamic performance. The incompressible Reynolds-averaged Navier-Stokes (RANS) equation in a three-dimensional coordinate system is solved by using the finite volume method. The shear stress transport (SST) k-ω two-equation turbulent model is also applied to simulate the turbulence. Numerical simulation results of the aerodynamic performance of the original model show good agreement with the tunnel experimental data. The results indicate that the elliptical parafoil model achieves the minimal drag coefficient among all the models, because the leading edge cut has changed the flow state, so that its lift coefficient is not the maximum. The swept back leading edge can obviously decrease the drag of a parafoil model. Because the middle part of a parafoil contributes more to effective lift, the model with a swept back leading edge achieves the maximal lift-drag ratio. Drag has a great impact on the lift-drag ratio, and the leading edge cut drag, which has only a two-dimensional effect, is one of the main sources of the total drag. This paper can provide reference for further studies on parafoil aerodynamic performance with different geometric parameters.%对带气室的展弦比为3的不同平面形状翼伞模型的流场进行了三维定常数值模拟,详细考察了平面形状对翼伞气动性能的影响.运用有限体积法对三维坐标系下不可压雷诺时均Navier-Stokes(RANS)方程进行了直接求解,采用剪切应力输运(SST)k-ω二方程湍流模型进行湍流模拟.数值模拟得出的原始翼伞的气动性能参数与试验数据在总趋势上符合很好,多种平面形状的翼伞模型计算结果表明:椭圆形翼伞模型获得最小阻力系数,前缘切口改变了上下缘流态使其升

  17. Aerodynamics of Small Vehicles

    Science.gov (United States)

    Mueller, Thomas J.

    In this review we describe the aerodynamic problems that must be addressed in order to design a successful small aerial vehicle. The effects of Reynolds number and aspect ratio (AR) on the design and performance of fixed-wing vehicles are described. The boundary-layer behavior on airfoils is especially important in the design of vehicles in this flight regime. The results of a number of experimental boundary-layer studies, including the influence of laminar separation bubbles, are discussed. Several examples of small unmanned aerial vehicles (UAVs) in this regime are described. Also, a brief survey of analytical models for oscillating and flapping-wing propulsion is presented. These range from the earliest examples where quasi-steady, attached flow is assumed, to those that account for the unsteady shed vortex wake as well as flow separation and aeroelastic behavior of a flapping wing. Experiments that complemented the analysis and led to the design of a successful ornithopter are also described.

  18. Aerodynamic Design and Performance of 7-35 Fans%7-35通风机的气动设计及其性能

    Institute of Scientific and Technical Information of China (English)

    朱之墀; 唐旭东; 黄东涛; 李嵩; 卢钰; 刘江林

    2001-01-01

    7-35通风机的气动设计采用离心通风机现代设计方法,其特点是引入三维粘性数值模拟分析离心通风机内部复杂流场,考虑了其各部件间的相互影响,数值预估离心通风机性能,并对现有工程设计方法作了重大改进,使其综合性能达到国际先进水平。%The aerodynamic design of 7-35 fans has been completed using a modern design method for centrifugal fans presented by the authors.The characteristics of the method include the introduction of 3-D viscous numerical simulation to analyze the internal complicated flow field of centrifugal fans,the consideration of the interference of its components ,the numerical prediction of fan performance and the major improvement of the existing engineering design method.Its compositive performances have reached the international advanced level.

  19. Optimizing X-ray mirror thermal performance using matched profile cooling.

    Science.gov (United States)

    Zhang, Lin; Cocco, Daniele; Kelez, Nicholas; Morton, Daniel S; Srinivasan, Venkat; Stefan, Peter M

    2015-09-01

    To cover a large photon energy range, the length of an X-ray mirror is often longer than the beam footprint length for much of the applicable energy range. To limit thermal deformation of such a water-cooled X-ray mirror, a technique using side cooling with a cooled length shorter than the beam footprint length is proposed. This cooling length can be optimized by using finite-element analysis. For the Kirkpatrick-Baez (KB) mirrors at LCLS-II, the thermal deformation can be reduced by a factor of up to 30, compared with full-length cooling. Furthermore, a second, alternative technique, based on a similar principle is presented: using a long, single-length cooling block on each side of the mirror and adding electric heaters between the cooling blocks and the mirror substrate. The electric heaters consist of a number of cells, located along the mirror length. The total effective length of the electric heater can then be adjusted by choosing which cells to energize, using electric power supplies. The residual height error can be minimized to 0.02 nm RMS by using optimal heater parameters (length and power density). Compared with a case without heaters, this residual height error is reduced by a factor of up to 45. The residual height error in the LCLS-II KB mirrors, due to free-electron laser beam heat load, can be reduced by a factor of ∼11 below the requirement. The proposed techniques are also effective in reducing thermal slope errors and are, therefore, applicable to white beam mirrors in synchrotron radiation beamlines.

  20. The effect of passive heating and head cooling on perception, cardiovascular function and cognitive performance in the heat.

    Science.gov (United States)

    Simmons, Shona E; Saxby, Brian K; McGlone, Francis P; Jones, David A

    2008-09-01

    The present study examined the effects of raising both skin temperature and core temperature, separately and in combination, on perceptions of heat-related fatigue (alertness, contentment, calmness and thermal comfort), cardiovascular function and on objective measures of cognitive performance (reaction time and accuracy). Ten (six males) subjects had cognitive performance assessed in three conditions; at low skin and low core temperature (LL), at high skin and low core temperature (HL) and at high skin and high core temperatures (HH). In one trial, subjects had their head and neck cooled (HC); the other trial was a control (CON). Raising skin temperature increased heart rate and decreased perception of thermal comfort (P temperature decreased perception of heat-related fatigue (P temperatures, cooling the head and neck improved feelings of heat-related fatigue (P temperature, whereas decrements in cognitive performance can be attributed to an elevated core temperature.

  1. Simultaneous effects of water spray and crosswind on performance of natural draft dry cooling tower

    Directory of Open Access Journals (Sweden)

    Ahmadikia Hossein

    2013-01-01

    Full Text Available To investigate the effect of water spray and crosswind on the effectiveness of the natural draft dry cooling tower (NDDCT, a three-dimensional model has been developed. Efficiency of NDDCT is improved by water spray system at the cooling tower entrance for high ambient temperature condition with and without crosswind. The natural and forced heat convection flow inside and around the NDDCT is simulated numerically by solving the full Navier-Stokes equations in both air and water droplet phases. Comparison of the numerical results with one-dimensional analytical model and the experimental data illustrates a well-predicted heat transfer rate in the cooling tower. Applying water spray system on the cooling tower radiators enhances the cooling tower efficiency at both no wind and windy conditions. For all values of water spraying rate, NDDCTs operate most effectively at the crosswind velocity of 3m/s and as the wind speed continues to rise to more than 3 m/s up to 12 m/s, the tower efficiency will decrease by approximately 18%, based on no-wind condition. The heat transfer rate of radiator at wind velocity 10 m/s is 11.5% lower than that of the no wind condition. This value is 7.5% for water spray rate of 50kg/s.

  2. INTEGRATED AERODYNAMIC MEASUREMENTS

    NARCIS (Netherlands)

    SCHUTTE, HK

    1992-01-01

    The myoelastic-aerodynamic model of phonation implies that aerodynamic factors are crucial to the evaluation of voice function, Subglottal pressure and mean flow rate represent the vocal power source. If they can be related to the magnitude of the radiated sound power, they may provide an index of v

  3. Reinforced aerodynamic profile

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to the prevention of deformations in an aerodynamic profile caused by lack of resistance to the bending moment forces that are created when such a profile is loaded in operation. More specifically, the invention relates to a reinforcing element inside an aerodynamic...

  4. 模型昆虫翼作非定常i运动时的气动力特性%AERODYNAMIC PROPERTIES OF A WING PERFORMING UNSTEADY ROTATIONAL MOTIONS

    Institute of Scientific and Technical Information of China (English)

    兰世隆; 孙茂

    2001-01-01

    The aerodynamic forces and flow structures of a wing of relatively small, aspect ratio in some unsteady rotational motions at low Reynolds number (Re = 100) are studied by numerically solving the Navier-Stokes equations. These motions include wing in constant-speed rotation after a fast start, wing accelerating and decelerating from one rotational speed to another,and wing rapidly pitching-up in constant-speed rotation. When a wing performing constant-speed rotation at small Reynolds number after started from rest at large angle of attack (α = 35°), a large lift coefficient can be maintained. The mechanism for the large lift coefficient is that for a rotating wing, the variation of the relative velocity along the wing-span causes a pressure gradient,centrifugal force also exists and hence a spanwise flow which can prevent the dynamic stall vortex from shedding. When a wing rapidly accelerating or decelerating from one rotational speed to another, or rapidly pitching-up during constant-speed rotation, even if the aspect ratio of the wing is small and the flow Reynolds number is low, large aerodynamic force can be obtained. During these rapid unsteady motions, new layers of strong vorticity are formed near the wing surfaces in very short time, resulting large time rate of change of the fluid impulse which is responsible for the generation of large aerodynamic force.%基于Navier-Stokes方程的数值解,研究了一模型昆虫翼在小雷诺数(Re=100)下作非定常运动时的气动力特性.这些运动包括:翼启动后的常速转动,快速加、减速转动,常速转动中快速上仰(模拟昆虫翼的上挥或下拍、翻转等运动).有如下结果:在小雷诺数下,模型昆虫翼以大攻角(α=35°)作常速转动运动时,由于失速涡不脱落,可产生较大的升力系数.其机理是:翼转动时,翼尖附近(该处线速度大)上翼面压强比翼根附近(该处线速度小)的小得多,因而存在展向压强梯度

  5. INVESTIGATION OF THE PERFORMANCE OF AN ATMOSPHERIC COOLING TOWER USING FRESH AND SALTED WATER

    Directory of Open Access Journals (Sweden)

    A Haddad

    2012-01-01

    Full Text Available Cooling towers are extensively used to evacuate large quantities of heat at modest temperatures through a change of phase of the flowing cooling fluid. Based on this classical principle, the present study investigates the influence of salty water on the heat exchange produced. For that purpose, experiments are carried out using fresh and salty water. Furthermore, a comparison with the results produced through an approach involving the solution of energy equation involving the flow of air on an evaporating film of fluid. The detailed results show a preponderance of fresh water over the salty.

  6. Performance investigation of a waste heat-driven 3-bed 2-evaporator adsorption cycle for cooling and desalination

    KAUST Repository

    Thu, Kyaw

    2016-06-13

    Environment-friendly adsorption (AD) cycles have gained much attention in cooling industry and its applicability has been extended to desalination recently. AD cycles are operational by low-temperature heat sources such as exhaust gas from processes or renewable energy with temperatures ranging from 55 °C to 85 °C. The cycle is capable of producing two useful effects, namely cooling power and high-grade potable water, simultaneously. This article discusses a low temperature, waste heat-powered adsorption (AD) cycle that produces cooling power at two temperature-levels for both dehumidification and sensible cooling while providing high-grade potable water. The cycle exploits faster kinetics for desorption process with one adsorber bed under regeneration mode while full utilization of the uptake capacity by adsorbent material is achieved employing two-stage adsorption via low-pressure and high-pressure evaporators. Type A++ silica gel with surface area of 863.6 m2/g and pore volume of 0.446 cm3/g is employed as adsorbent material. A comprehensive numerical model for such AD cycle is developed and the performance results are presented using assorted hot water and cooling water inlet temperatures for various cycle time arrangements. The cycle is analyzed in terms of key performance indicators i.e.; the specific cooling power (SCP), the coefficient of performance (COP) for both evaporators and the overall system, the specific daily water production (SDWP) and the performance ratio (PR). Further insights into the cycle performance are scrutinized using a Dühring diagram to depict the thermodynamic states of the processes as well as the vapor uptake behavior of adsorbent. In the proposed cycle, the adsorbent materials undergo near saturation conditions due to the pressurization effect from the high pressure evaporator while faster kinetics for desorption process is exploited, subsequently providing higher system COP, notably up to 0.82 at longer cycle time while the

  7. The Cooling and Lubrication Performance of Graphene Platelets in Micro-Machining Environments

    Science.gov (United States)

    Chu, Bryan

    The research presented in this thesis is aimed at investigating the use of graphene platelets (GPL) to address the challenges of excessive tool wear, reduced part quality, and high specific power consumption encountered in micro-machining processes. There are two viable methods of introducing GPL into micro-machining environments, viz., the embedded delivery method, where the platelets are embedded into the part being machined, and the external delivery method, where graphene is carried into the cutting zone by jetting or atomizing a carrier fluid. The study involving the embedded delivery method is focused on the micro-machining performance of hierarchical graphene composites. The results of this study show that the presence of graphene in the epoxy matrix improves the machinability of the composite. In general, the tool wear, cutting forces, surface roughness, and extent of delamination are all seen to be lower for the hierarchical composite when compared to the conventional two-phase glass fiber composite. These improvements are attributed to the fact that graphene platelets improve the thermal conductivity of the matrix, provide lubrication at the tool-chip interface and also improve the interface strength between the glass fibers and the matrix. The benefits of graphene are seen to also carry over to the external delivery method. The platelets provide improved cooling and lubrication performance to both environmentally-benign cutting fluids as well as to semi-synthetic cutting fluids used in micro-machining. The cutting performance is seen to be a function of the geometry (i.e., lateral size and thickness) and extent of oxygen-functionalization of the platelet. Ultrasonically exfoliated platelets (with 2--3 graphene layers and lowest in-solution characteristic lateral length of 120 nm) appear to be the most favorable for micro-machining applications. Even at the lowest concentration of 0.1 wt%, they are capable of providing a 51% reduction in the cutting

  8. Improved Performance of an Air Cooled Condenser (ACC) Using SPX Wind Guide Technology at Coal-Based Thermoelectric Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Ken Mortensen

    2010-12-31

    This project added a new airflow enhancement technology to an existing ACC cooling process at a selected coal power plant. Airflow parameters and efficiency improvement for the main plant cooling process using the applied technology were determined and compared with the capabilities of existing systems. The project required significant planning and pre-test execution in order to reach the required Air Cooled Condenser system configuration for evaluation. A host Power Plant ACC system had to be identified, agreement finalized, and addition of the SPX ACC Wind Guide Technology completed on that site. Design of the modification, along with procurement, fabrication, instrumentation, and installation of the new airflow enhancement technology were executed. Baseline and post-modification cooling system data was collected and evaluated. The improvement of ACC thermal performance after SPX wind guide installation was clear. Testing of the improvement indicates there is a 5% improvement in heat transfer coefficient in high wind conditions and 1% improvement at low wind speed. The benefit increased with increasing wind speed. This project was completed on schedule and within budget.

  9. PERFORMANCE OF A SOLID DESICCANT BASED EVAPORATIVE COOLING SYSTEM IN WARM AND HUMID CLIMATIC ZONE OF INDIA

    Directory of Open Access Journals (Sweden)

    HEMANT PARMAR

    2010-10-01

    Full Text Available Vapour compression based air conditioners are being used for comfort cooling in residences, offices and commercial buildings in many countries throughout the world. Several issues arise seriously challenge the conventional technology which include harmful impact of CFCs and HCFCs on environment, energy and cost problems etc. However use of low energy and eco friendly techniques may be helpful to overcome these problems up to some extent. The evaporative cooling may be considered as one of such eco friendly methods of achieving comfortable conditions in buildings during summer. These systems have great potential to provide thermal comfort in places where ambient air humidity is low. Such systems alone are not efficient for humidclimatic conditions. However such systems can be used if combined with desiccant based dehumidifier. India with its widely different climates has been divided into six climatic zones viz. Hot and Dry, Moderate, Warm and Humid, Composite, Cold and Cloudy and Cold and Sunny. This paper examines the potential of a simple desiccant evaporative cooling cycle in five selected cities in Warm and Humid climatic zone of India. The coefficient of performance (COP has been computed for each location and compared. It has been found that COP for different cities varies in the range of 0.14 to 0.21. Mumbai (coastal city has been identified as the city where desiccant evaporative cooling system can be operated with higher COP compared to that of other cities in the same climatic zone.

  10. Analysis of the cool down related cavity performance of the European XFEL vertical acceptance tests

    CERN Document Server

    Wenskat, Marc

    2016-01-01

    It has been reported that the cool down dynamics across $T_c$ has a significant influence on the observed quality factors $Q_0$ of a cavity, which is most likely due to trapped flux. In this document we show the results of the investigation if such a correlation can be observed during the European XFEL cavity production.

  11. Optomechanical performance of 3D-printed mirrors with embedded cooling channels and substructures

    Science.gov (United States)

    Mici, Joni; Rothenberg, Bradley; Brisson, Erik; Wicks, Sunny; Stubbs, David M.

    2015-09-01

    Advances in 3D printing technology allow for the manufacture of topologically complex parts not otherwise feasible through conventional manufacturing methods. Maturing metal and ceramic 3D printing technologies are becoming more adept at printing complex shapes, enabling topologically intricate mirror substrates. One application area that can benefit from additive manufacturing is reflective optics used in high energy laser (HEL) systems that require materials with a low coefficient of thermal expansion (CTE), high specific stiffness, and (most importantly) high thermal conductivity to effectively dissipate heat from the optical surface. Currently, the limits of conventional manufacturing dictate the topology of HEL optics to be monolithic structures that rely on passive cooling mechanisms and high reflectivity coatings to withstand laser damage. 3D printing enables the manufacture of embedded cooling channels in metallic mirror substrates to allow for (1) active cooling and (2) tunable structures. This paper describes the engineering and analysis of an actively cooled composite optical structure to demonstrate the potential of 3D printing on the improvement of optomechanical systems.

  12. Cool Farm Tool – Potato: Model Description and Performance of Four Production Systems

    NARCIS (Netherlands)

    Haverkort, A.J.; Hillier, J.G.

    2011-01-01

    The Cool Farm Tool – Potato (CFT-Potato) is a spreadsheet programme that allows the calculation of the amount of CO2 equivalents that it costs to produce 1 t of potato. The spreadsheet was adapted from an original generic version of the tool, and completed for potato production in diverse production

  13. Thermal performance demonstration of a prototype internally cooled nose tip/forebody/window assembly

    Science.gov (United States)

    Wojciechowski, Carl J.; Brooks, Lori C.; Teal, Gene; Karu, Zain; Kalin, David A.; Jones, Gregory W.; Romero, Harold

    1996-11-01

    Internally liquid cooled apertures (windows) installed in a full size forebody have been characterized under high heat flux conditions representative of endoatmospheric flight. Analysis and test data obtained in the laboratory and at arc heater test facilities at Arnold Engineering Development Center and NASA Ames are presented in this paper. Data for several types of laboratory bench tests are presented: transmission interferometry and imaging, coolant pressurization effects on optical quality, and coolant flow rate calibrations for both the window and other internally cooled components. Initially, using heat transfer calibration models identical in shape to the flight test articles, arc heater facility thermal test environments were obtained at several conditions representative of full flight thermal environments. Subsequent runs tested the full-up flight article including nosetip, forebody and aperture for full flight duplication of surface heating rates and exposure ties. Pretest analyses compared will to test measurements. These data demonstrate a very efficient internal liquid cooling design which can be applied to other applications such as cooled mirrors for high heat flux applications.

  14. Performance Analysis of a Greenhouse Fan-Pad Cooling System: Gradients of Horizontal Temperature and Relative Humidity

    OpenAIRE

    DAYIOĞLU, Mehmet Ali

    2014-01-01

    An experimental study was conducted to determine the performance parameters of system, as well as gradients of temperature and humidity along greenhouse when opening fan-ped cooling system. Measurements related with greenhouse environment were carried out by using seven sensors for different locations, as well as portable instruments. For this purpose, the five digital temperature and humidity sensors and two pyranometers were used during experiments. Among them, two were located outside gree...

  15. Energy Performance Assessment of Radiant Cooling System through Modeling and Calibration at Component Level

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Yasin [Malaviya National Institute of Technology (MNIT), Jaipur, India; Mathur, Jyotirmay [Malaviya National Institute of Technology (MNIT), Jaipur, India; Bhandari, Mahabir S [ORNL

    2016-01-01

    The paper describes a case study of an information technology office building with a radiant cooling system and a conventional variable air volume (VAV) system installed side by side so that performancecan be compared. First, a 3D model of the building involving architecture, occupancy, and HVAC operation was developed in EnergyPlus, a simulation tool. Second, a different calibration methodology was applied to develop the base case for assessing the energy saving potential. This paper details the calibration of the whole building energy model to the component level, including lighting, equipment, and HVAC components such as chillers, pumps, cooling towers, fans, etc. Also a new methodology for the systematic selection of influence parameter has been developed for the calibration of a simulated model which requires large time for the execution. The error at the whole building level [measured in mean bias error (MBE)] is 0.2%, and the coefficient of variation of root mean square error (CvRMSE) is 3.2%. The total errors in HVAC at the hourly are MBE = 8.7% and CvRMSE = 23.9%, which meet the criteria of ASHRAE 14 (2002) for hourly calibration. Different suggestions have been pointed out to generalize the energy saving of radiant cooling system through the existing building system. So a base case model was developed by using the calibrated model for quantifying the energy saving potential of the radiant cooling system. It was found that a base case radiant cooling system integrated with DOAS can save 28% energy compared with the conventional VAV system.

  16. A climatology of formation conditions for aerodynamic contrails

    Directory of Open Access Journals (Sweden)

    K. Gierens

    2013-11-01

    Full Text Available Aircraft at cruise levels can cause two kinds of contrails, the well known exhaust contrails and the less well-known aerodynamic contrails. While the possible climate impact of exhaust contrails has been studied for many years, research on aerodynamic contrails began only a few years ago and nothing is known about a possible contribution of these ice clouds to climate impact. In order to make progress in this respect, we first need a climatology of their formation conditions and this is given in the present paper. Aerodynamic contrails are defined here as line shaped ice clouds caused by aerodynamically triggered cooling over the wings of an aircraft in cruise which become visible immediately at the trailing edge of the wing or close to it. Effects at low altitudes like condensation to liquid droplets and their potential heterogeneous freezing are excluded from our definition. We study atmospheric conditions that allow formation of aerodynamic contrails. These conditions are stated and then applied to atmospheric data: first to a special case where an aerodynamic contrail was actually observed and then to a full year of global reanalysis data. We show where, when (seasonal variation, and how frequently (probability aerodynamic contrails can form, and how this relates to actual patterns of air traffic. We study the formation of persistent aerodynamic contrails as well. Furthermore, we check whether aerodynamic and exhaust contrails can coexist in the atmosphere. We show that visible aerodynamic contrails are possible only in an altitude range between roughly 540 and 250 hPa, and that the ambient temperature is the most important parameter, not the relative humidity. Finally, we argue that currently aerodynamic contrails have a much smaller climate effect than exhaust contrails, which may however change in future with more air traffic in the tropics.

  17. Experimental diagnosis of the influence of operational variables on the performance of a solar absorption cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Venegas, M.; Rodriguez-Hidalgo, M.C.; Lecuona, A.; Rodriguez, P.; Gutierrez, G. [Dpto. Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, Avda. Universidad 30, 28911 Leganes, Madrid (Spain); Salgado, R. [Dpto. Ingenieria Mecanica, Universidad Interamericana de Puerto Rico, Recinto de Bayamon, 500 Carretera Dr. John Will Harris Bayamon, PR 00957-6257 (United States)

    2011-04-15

    This paper presents the analysis of the performance of a solar cooling facility along one summer season using a commercial single-effect water-lithium bromide absorption chiller aiming at domestic applications. The facility works only with solar energy using flat plate collectors and it is located at Universidad Carlos III de Madrid, Spain. The statistical analysis performed with the gathered data shows the influence of five daily operational variables on the system performance. These variables are solar energy received along the day (H) and the average values, along the operating period of the solar cooling facility (from sunrise to the end of the cold-water production), of the ambient temperature (anti T), the wind velocity magnitude (V), the wind direction ({theta}) and the relative humidity (RH). First order correlation functions are given. The analysis of the data allows concluding that the most influential variables on the daily cooling energy produced and the daily averaged solar COP are H, V and {theta}. The period length of cold-water production is determined mainly by H and anti T. (author)

  18. Temperature Field Accurate Modeling and Cooling Performance Evaluation of Direct-Drive Outer-Rotor Air-Cooling In-Wheel Motor

    Directory of Open Access Journals (Sweden)

    Feng Chai

    2016-10-01

    Full Text Available High power density outer-rotor motors commonly use water or oil cooling. A reasonable thermal design for outer-rotor air-cooling motors can effectively enhance the power density without the fluid circulating device. Research on the heat dissipation mechanism of an outer-rotor air-cooling motor can provide guidelines for the selection of the suitable cooling mode and the design of the cooling structure. This study investigates the temperature field of the motor through computational fluid dynamics (CFD and presents a method to overcome the difficulties in building an accurate temperature field model. The proposed method mainly includes two aspects: a new method for calculating the equivalent thermal conductivity (ETC of the air-gap in the laminar state and an equivalent treatment to the thermal circuit that comprises a hub, shaft, and bearings. Using an outer-rotor air-cooling in-wheel motor as an example, the temperature field of this motor is calculated numerically using the proposed method; the results are experimentally verified. The heat transfer rate (HTR of each cooling path is obtained using the numerical results and analytic formulas. The influences of the structural parameters on temperature increases and the HTR of each cooling path are analyzed. Thereafter, the overload capability of the motor is analyzed in various overload conditions.

  19. The Effect of Different Rail Heights on Aerodynamic Performance of Straddle Type Monorail Vehicles%不同轨面高度对跨坐式单轨车气动性能的影响

    Institute of Scientific and Technical Information of China (English)

    杜子学; 张杰; 赵科

    2011-01-01

    Based on the head model of Straddle-type Monorail Vehicle,by application of numerical simulation method and by setting different computing domains, the height of straddle type monorail vehicle of the orbital plane and ground is simulated and the impact of different orbital plane height on the aerodynamic performance under the windward condition is analyzed. The results of the analyses show that as the rail surface height increases, the monorail vehicle's aerodynamic performance improves along with it and at the height of 6m above, aerodynamic performance changes of monorail vehicle tend to smooth. But there is a little difference in wind resistance under the different orbital plane height. This indicates that the change in orbital plane height has a little effect on its aerodynamic performance. The orbital plane height setting of Chongqing straddle type monorail vehicle for orbital plane heights of different sections is reasonable.%基于踌坐武单轨车头车模型,运用数值模拟方法,通过设置不同的计算域来模拟跨坐式单轨车轨面与地面的高度,分析在迎风条件下不同轨面高度对其气动性能的影响.分析结果表明:随着轨面高度的增加,单轨车的气动性能随之改善,且在离地高度6m以上单轨车的气动性能变化趋于平缓.但不同轨面高度下的风阻值差异较小,这表明单轨车轨面高度的变化对其气动性能影响较小,重庆跨坐式单轨车不同路段轨面高度的设置是合理的.

  20. INFLUENCE FACTORS STUDY ON THE AERODYNAMIC PERFORMANCE OF A HORIZONTAL AXIS WIND TURBINE ROTOR%水平轴风机气动性能影响因素研究

    Institute of Scientific and Technical Information of China (English)

    李军向; 薛忠民; 王继辉

    2008-01-01

    设计高性能水平轴风机是如今风机设计的趋势.风机工作环境恶劣,要计算所有因素对风机性能的影响不太现实.本文运用动量理论和叶素理论分析了实度、桨矩角、锥角、倾角和叶片厚度对风轮气动性能的影响.分析表明,风轮气动性能对实度、桨矩角敏感度高,叶片厚度对风轮气动性能影响不大.对敏感参数进行优化设计,有利于风机在低成本情况下提高其性能.%High aerodynamic performance is desirable for a horizontal axis wind turbine design. Wind turbine including rotor with complicated structure works in a quite execrable condition, it is unpractical to calculate the aerodynamic performance with all influence factors considered. In this paper, the effects of various factors including solidity, pitch angle, cone angle, tilt angle, yaw angle and blade thickness on the aerodynamic performance of horizontal axis wind turbine rotor were analyzed based on momentum and blade element theory. Such investigation shows that the aerodynamic performance is sensitive to some factors, and others not. Proper parameters can be selected to optimize the design of a wind turbine to capture as much energy from wind as possible with low cost.

  1. Effects of mixed-method cooling on recovery of medium-fast bowling performance in hot conditions on consecutive days.

    Science.gov (United States)

    Minett, Geoffrey M; Duffield, Rob; Kellett, Aaron; Portus, Marc

    2012-01-01

    This investigation examined physiological and performance effects of cooling on recovery of medium-fast bowlers in the heat. Eight, medium-fast bowlers completed two randomised trials, involving two sessions completed on consecutive days (Session 1: 10-overs and Session 2: 4-overs) in 31 ± 3°C and 55 ± 17% relative humidity. Recovery interventions were administered for 20 min (mixed-method cooling vs. control) after Session 1. Measures included bowling performance (ball speed, accuracy, run-up speeds), physical demands (global positioning system, counter-movement jump), physiological (heart rate, core temperature, skin temperature, sweat loss), biochemical (creatine kinase, C-reactive protein) and perceptual variables (perceived exertion, thermal sensation, muscle soreness). Mean ball speed was higher after cooling in Session 2 (118.9 ± 8.1 vs. 115.5 ± 8.6 km · h⁻¹; P = 0.001; d = 0.67), reducing declines in ball speed between sessions (0.24 vs. -3.18 km · h⁻¹; P = 0.03; d = 1.80). Large effects indicated higher accuracy in Session 2 after cooling (46.0 ± 11.2 vs. 39.4 ± 8.6 arbitrary units [AU]; P = 0.13; d = 0.93) without affecting total run-up speed (19.0 ± 3.1 vs. 19.0 ± 2.5 km · h⁻¹; P = 0.97; d = 0.01). Cooling reduced core temperature, skin temperature and thermal sensation throughout the intervention (P = 0.001-0.05; d = 1.31-5.78) and attenuated creatine kinase (P = 0.04; d = 0.56) and muscle soreness at 24-h (P = 0.03; d = 2.05). Accordingly, mixed-method cooling can reduce thermal strain after a 10-over spell and improve markers of muscular damage and discomfort alongside maintained medium-fast bowling performance on consecutive days in hot conditions.

  2. Design, construction and cooling system performance of a prototype cryogenic stopping cell for the Super-FRS at FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Ranjan, M. [KVI-Center for Advanced Radiation Technology, University of Groningen - Zernikelaan 25, 9747 AA Groningen (Netherlands); Dendooven, P., E-mail: p.g.dendooven@rug.nl [KVI-Center for Advanced Radiation Technology, University of Groningen - Zernikelaan 25, 9747 AA Groningen (Netherlands); Purushothaman, S. [GSI Helmholtz Centre for Heavy Ion Research - Planckstraße 1, 64291 Darmstadt (Germany); Dickel, T. [GSI Helmholtz Centre for Heavy Ion Research - Planckstraße 1, 64291 Darmstadt (Germany); II. Physikalisches Institut, Justus-Liebig-Universität Gießen - Heinrich-Buff-Ring 16, 35392 Gießen (Germany); Reiter, M.P. [II. Physikalisches Institut, Justus-Liebig-Universität Gießen - Heinrich-Buff-Ring 16, 35392 Gießen (Germany); Ayet, S. [GSI Helmholtz Centre for Heavy Ion Research - Planckstraße 1, 64291 Darmstadt (Germany); Haettner, E. [GSI Helmholtz Centre for Heavy Ion Research - Planckstraße 1, 64291 Darmstadt (Germany); II. Physikalisches Institut, Justus-Liebig-Universität Gießen - Heinrich-Buff-Ring 16, 35392 Gießen (Germany); Moore, I.D. [University of Jyväskylä - FI-40014, Jyväskylä (Finland); Kalantar-Nayestanaki, N. [KVI-Center for Advanced Radiation Technology, University of Groningen - Zernikelaan 25, 9747 AA Groningen (Netherlands); and others

    2015-01-11

    A cryogenic stopping cell for stopping energetic radioactive ions and extracting them as a low energy beam was developed. This first ever cryogenically operated stopping cell serves as prototype device for the Low-Energy Branch of the Super-FRS at FAIR. The cell has a stopping volume that is 1 m long and 25 cm in diameter. Ions are guided by a DC field along the length of the stopping cell and by a combined RF and DC fields provided by an RF carpet at the exit-hole side. The ultra-high purity of the stopping gas required for optimum ion survival is reached by cryogenic operation. The design considerations and construction of the cryogenic stopping cell, as well as some performance characteristics, are described in detail. Special attention is given to the cryogenic aspects in the design and construction of the stopping cell and the cryocooler-based cooling system. The cooling system allows the operation of the stopping cell at any desired temperature between about 70 K and room temperature. The cooling system performance in realistic on-line conditions at the FRS Ion Catcher Facility at GSI is discussed. A temperature of 110 K at which efficient ion survival was observed is obtained after 10 h of cooling. A minimum temperature of the stopping gas of 72 K was reached. The expertise gained from the design, construction and performance of the prototype cryogenic stopping cell has allowed the development of a final version for the Low-Energy Branch of the Super-FRS to proceed.

  3. Unstructured Grid Euler Method Assessment for Aerodynamics Performance Prediction of the Complete TCA Configuration at Supersonic Cruise Speed

    Science.gov (United States)

    Ghaffari, Farhad

    1999-01-01

    Unstructured grid Euler computations, performed at supersonic cruise speed, are presented for a proposed high speed civil transport configuration, designated as the Technology Concept Airplane (TCA) within the High Speed Research (HSR) Program. The numerical results are obtained for the complete TCA cruise configuration which includes the wing, fuselage, empennage, diverters, and flow through nacelles at Mach 2.4 for a range of angles-of-attack and sideslip. The computed surface and off-surface flow characteristics are analyzed and the pressure coefficient contours on the wing lower surface are shown to correlate reasonably well with the available pressure sensitive paint results, particularly, for the complex shock wave structures around the nacelles. The predicted longitudinal and lateral/directional performance characteristics are shown to correlate very well with the measured data across the examined range of angles-of-attack and sideslip. The results from the present effort have been documented into a NASA Controlled-Distribution report which is being presently reviewed for publication.

  4. Radiation protection performance for the dismantling of the WWR-M primary cooling circuit.

    Science.gov (United States)

    Lobach, Yu N; Luferenko, E D; Shevel, V N

    2014-12-01

    The WWR-M is a light-water-cooled and moderated heterogonous research reactor with a thermal output of 10 MW. The reactor has been in operation for >50 y and has had an excellent safety record. A non-hermeticity of the inlet line of the primary cooling circuit (PCC) was found, and the only reasonable technical solution was the complete replacement of the PCC inlet and outlet pipe lines. Such a replacement was a challenging technical task due to the necessity to handle large size components with complex geometries under conditions of high-level radiation fields, and therefore, it required detailed planning aiming to reduce staff exposure. This paper describes the dismantling and removal of the PCC components focusing on radiation protection issues.

  5. Experimental and numerical analysis of the cooling performance of water spraying systems during a fire.

    Directory of Open Access Journals (Sweden)

    YaoHan Chen

    Full Text Available The water spray systems are effective protection systems in the confined or unconfined spaces to avoid the damage to building structures since the high temperature when fires occur. NFPA 15 and 502 have suggested respectively that the factories or vehicle tunnels install water spray systems to protect the machinery and structures. This study discussed the cooling effect of water spray systems in experimental and numerical analyses. The actual combustion of woods were compared with the numerical simulations. The results showed that although the flame continued, the cooling effects by water spraying process within 120 seconds were obvious. The results also indicated that the simulation results of the fifth version Fire Dynamics Simulator (FDS overestimated the space temperature before water spraying in the case of the same water spray system.

  6. Experimental and numerical analysis of the cooling performance of water spraying systems during a fire.

    Science.gov (United States)

    Chen, YaoHan; Su, ChungHwei; Tseng, JoMing; Li, WunJie

    2015-01-01

    The water spray systems are effective protection systems in the confined or unconfined spaces to avoid the damage to building structures since the high temperature when fires occur. NFPA 15 and 502 have suggested respectively that the factories or vehicle tunnels install water spray systems to protect the machinery and structures. This study discussed the cooling effect of water spray systems in experimental and numerical analyses. The actual combustion of woods were compared with the numerical simulations. The results showed that although the flame continued, the cooling effects by water spraying process within 120 seconds were obvious. The results also indicated that the simulation results of the fifth version Fire Dynamics Simulator (FDS) overestimated the space temperature before water spraying in the case of the same water spray system.

  7. Effects of a Novel Cooling Shirt on Various Physical Performance Parameters in Elite Athletes

    Science.gov (United States)

    2015-06-03

    soldiers has been compared to elite athletes. The physical demands required during training and battle, the types of clothing and protective...related illness requires up to four members of a squadron to carry him or her to a safe location [7]. Therefore, proper heat management is paramount to...specially cut-to- size cryotherapy material in place. The subjects were then counter-balanced, with half of the subjects “loaded” with the cooling material

  8. Thermodynamic performance experiment and cooling number calculation of a counter-flow spray humidifier in the HAT cycle

    Institute of Scientific and Technical Information of China (English)

    Yuzhang WANG; Yixing LI; Shilie WENG; Yonghong WANG

    2008-01-01

    An experimental investigation of the ther-modynamic performance of a counter-flow spray humidi-fier was conducted on the basis of theoretical analysis of the heat and mass transfer mechanism inside the humidi-fier. Critical parameters such as the temperature and relative humidity of air and the temperature of water at the inlet and outlet were measured. The influence of every measured parameter on the thermal performance of the humidifier was obtained under different experimental conditions. The cooling number, whose variation was also obtained, was calculated according to the measured data. The experimental results show that both the temperature and the temperature increment of outlet humid air and the temperature of outlet water increase with an increase of the water-gas ratio, whereas the cooling number decreases. Under all experimental conditions, the outlet humid air reaches or is close to the saturation level. The lower cooling number is favorable for the system, but it has an optimal value for a certain humidifier.

  9. Effects of Tube Diameter and Tubeside Fin Geometry on the Heat Transfer Performance of Air-Cooled Condensers

    Science.gov (United States)

    Wang, H. S.; Honda, Hiroshi

    A theoretical study has been made on the effects of tube diameter and tubeside fin geometry on the heat transfer performance of air-cooled condensers. Extensive numerical calculations of overall heat transfer from refrigerant R410A flowing inside a horizontal microfin tube to ambient air were conducted for a typical operating condition of the air-cooled condenser. The tubeside heat transfer coefficient was calculated by applying a modified stratified flow model developed by Wang et al.8). The numerical results show that the effects of tube diameter, fin height, fin number and helix angle of groove are significant, whereas those of the width of flat portion at the fin tip, the radius of round corner at the fin tip and the fin half tip angle are small.

  10. Computational Study of the Impact of Unsteadiness on the Aerodynamic Performance of a Variable- Speed Power Turbine

    Science.gov (United States)

    Welch, Gerard E.

    2012-01-01

    The design-point and off-design performance of an embedded 1.5-stage portion of a variable-speed power turbine (VSPT) was assessed using Reynolds-Averaged Navier-Stokes (RANS) analyses with mixing-planes and sector-periodic, unsteady RANS analyses. The VSPT provides one means by which to effect the nearly 50 percent main-rotor speed change required for the NASA Large Civil Tilt-Rotor (LCTR) application. The change in VSPT shaft-speed during the LCTR mission results in blade-row incidence angle changes of as high as 55 . Negative incidence levels of this magnitude at takeoff operation give rise to a vortical flow structure in the pressure-side cove of a high-turn rotor that transports low-momentum flow toward the casing endwall. The intent of the effort was to assess the impact of unsteadiness of blade-row interaction on the time-mean flow and, specifically, to identify potential departure from the predicted trend of efficiency with shaft-speed change of meanline and 3-D RANS/mixing-plane analyses used for design.

  11. Energy and Exergy Performances of Air-Based vs. Water-Based Heating and Cooling Systems: A Case Study of a Single-Family House

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2016-01-01

    -based systems, an air heating and cooling system, and a radiant floor heating and cooling system were chosen, respectively. A single-family house was used as a case study assuming that different space heating and cooling systems were used to condition the indoor space of this house. In addition to the thermal...... energy and exergy inputs to the system, energy and exergy inputs to the auxiliary components were also studied. Both heating and cooling cases were considered and three climatic zones were studied; Copenhagen (Denmark), Yokohama (Japan), and Ankara (Turkey). The analysis showed that the water......-based radiant heating and cooling system performed better than the air-based system both in terms of energy and exergy input to the heating/cooling plant. The relative benefits of the water-based system over the air-based system vary depending on the climatic zone. The air-based system also requires higher...

  12. Influence of anisotropic piezoelectric actuators on wing aerodynamic forces

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Changing the shape of an airfoil to enhance overall aircraft performance has always been a goal of aircraft designers. Using smart material to reshape the wing can improve aerodynamic performance. The influence of anisotropic effects of piezoelectric actuators on the aerodynamic characteristics of a simplified HALE wing model was investigated. Test verification was conducted.

  13. Influence of anisotropic piezoelectric actuators on wing aerodynamic forces

    Institute of Scientific and Technical Information of China (English)

    GUAN De; LI Min; LI Wei; WANG MingChun

    2008-01-01

    Changing the shape of an airfoil to enhance overall aircraft performance has always been s goal of aircraft designers.Using smart material to reshape the wing can improve aerodynamic performance.The influence of anisotropic effects of piezo-electric actuators on the aerodynamic characteristics of a simplified HALE wing model was investigated.Test verification was conducted.

  14. Spacecraft aerodynamics and trajectory simulation during aerobraking

    Institute of Scientific and Technical Information of China (English)

    Wen-pu ZHANG; Bo HAN; Cheng-yi ZHANG

    2010-01-01

    This paper uses a direct simulation Monte Carlo(DSMC)approach to simulate rarefied aerodynamic characteristics during the aerobraking process of the NASA Mars Global Surveyor(MGS)spacecraft.The research focuses on the flowfield and aerodynamic characteristics distribution under various free stream densities.The variation regularity of aerodynamic coefficients is analyzed.The paper also develops an aerodynamics-aeroheating-trajectory integrative simulation model to preliminarily calculate the aerobraking orbit transfer by combining the DSMC technique and the classical kinematics theory.The results show that the effect of the planetary atmospheric density,the spacecraft yaw,and the pitch attitudes on the spacecraft aerodynamics is significant.The numerical results are in good agreement with the existing results reported in the literature.The aerodynamics-aeroheating-trajectory integrative simulation model can simulate the orbit tran,sfer in the complete aerobraking mission.The current results of the spacecraft trajectory show that the aerobraking maneuvers have good performance of attitude control.

  15. Aerodynamic Shutoff Valve

    Science.gov (United States)

    Horstman, Raymond H.

    1992-01-01

    Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.

  16. Development and performance of a large-scale, transonic turbine blade cascade facility for aerodynamic studies of merging coolant-mainstream flows

    Science.gov (United States)

    Al-Sayeh, Amjad Isaaf

    1998-11-01

    A new, large scale, linear cascade facility of turbine blades has been developed for the experimental exploration of the aerodynamic aspects of film cooling technology. Primary interest is in the mixing of the ejected coolant with the mainstream, at both subsonic and supersonic mainstream Mach numbers at the cascade exit. In order to achieve a spatial resolution adequate for the exploration of details on the scale of the coolant ejection holes, the cascade dimensions were maximized, within the limitations of the air supply system. The cascade contains four blades (three passages) with 14.05 cm axial chord, 17.56 cm span and a design total turning angle of 130.6 degrees. Exit Mach numbers range from 0.6 to 1.5 and Reynolds numbers from 0.5 to 1.5 million. The air supply system capacity allows run times up to five minutes at maximum flow rates. A coolant supply system has been built to deliver mixtures of SFsb6 and air to simulate coolant/mainstream density ratios up to 2. The cascade contains several novel features. A full-perimeter bleed slot upstream of the blades is used to remove the approach boundary layer from all four walls, to improve the degree of two-dimensionality. The exit flow is bounded by two adjustable tailboards that are hinged at the trailing edges and actuated to set the exit flow direction according to the imposed pressure ratio. The boards are perforated and subjected to mass removal near the blades, to minimize the undesirable reflection of shocks and expansion waves. A probe actuator is incorporated that allows continuous positioning of probes in the exhaust stream, in both the streamwise and pitchwise directions. Diagnostic methods include extensive surface pressure taps on the approach and exhaust ducts and on the blade surfaces. The large size permitted as many as 19 taps on the trailing edge itself. Shadowgraph and schlieren are available. A three-prong wake probe has been constructed to simultaneously measure total and static pressures

  17. Performance of a 4 Kelvin pulse-tube cooled cryostat with dc SQUID amplifiers for bolometric detector testing

    CERN Document Server

    Barron, Darcy; Keating, Brian; Quillin, Ron; Stebor, Nathan; Wilson, Brandon

    2013-01-01

    The latest generation of cosmic microwave background (CMB) telescopes is searching for the undetected faint signature of gravitational waves from inflation in the polarized signal of the CMB. To achieve the unprecedented levels of sensitivity required, these experiments use arrays of superconducting Transition Edge Sensor (TES) bolometers that are cooled to sub-Kelvin temperatures for photon-noise limited performance. These TES detectors are read out using low- noise SQUID amplifiers. To rapidly test these detectors and similar devices in a laboratory setting, we constructed a cryogenic refrigeration chain consisting of a commercial two-stage pulse-tube cooler, with a base temperature of 3 K, and a closed-cycle 3He/4He/3He sorption cooler, with a base temperature of 220 mK. A commercial dc SQUID system, with sensors cooled to 4 K, was used as a highly-sensitive cryogenic ammeter. Due to the extreme sensitivity of SQUIDs to changing magnetic fields, there are several challenges involving cooling them with puls...

  18. Energy and Exergy Analysis for Improving the Energy Performance of Air-Cooled Liquid Chillers by Different Condensing-Coil Configurations

    Directory of Open Access Journals (Sweden)

    Tzong-Shing Lee

    2012-03-01

    Full Text Available This study constructed a parameter analysis for improving the energy performance of air-cooled water chillers by altering the angle configuration of the condenser coils. The mathematical models for energy and exergy analyses of the individual components and overall system of air-cooled water chillers are presented. This study investigated the potential enhancement of performance efficiency in air-cooled chillers and the energy conversion efficiency of each component, in order to determine how the angle configuration of condenser coils influences chiller performance. This study found that the overall performance of an air-cooled chiller could be improved by approximately 3.4%, and the total irreversibility could be reduced by approximately 2.7%. With each 1% increase in average wind speed over the condenser coils, the overall performance of an air‑cooled chiller was found to be enhanced by approximately 0.43%, and its total irreversibility was reduced by approximately 0.35%. The results of this study can be effectively applied to air-cooled condenser units, and can provide an important basis of reference for developing and enhancing the energy efficiency of air-cooled chillers.

  19. Carbohydrate ingestion and pre-cooling improves exercise capacity following soccer-specific intermittent exercise performed in the heat.

    Science.gov (United States)

    Clarke, N D; Maclaren, D P M; Reilly, T; Drust, B

    2011-07-01

    Ingestion of carbohydrate and reducing core body temperature pre-exercise, either separately or combined, may have ergogenic effects during prolonged intermittent exercise in hot conditions. The aim of this investigation was to examine the effect of carbohydrate ingestion and pre-cooling on the physiological responses to soccer-specific intermittent exercise and the impact on subsequent high-intensity exercise performance in the heat. Twelve male soccer players performed a soccer-specific intermittent protocol for 90 min in the heat (30.5°C and 42.2% r.h.) on four occasions. On two occasions, the participants underwent a pre-cooling manoeuvre. During these sessions either a carbohydrate-electrolyte solution (CHOc) or a placebo was consumed at (PLAc). During the remaining sessions either the carbohydrate-electrolyte solution (CHO) or placebo (PLA) was consumed. At 15-min intervals throughout the protocol participants performed a mental concentration test. Following the soccer-specific protocol participants performed a self-chosen pace test and a test of high-intensity exercise capacity. The period of pre-cooling significantly reduced core temperature, muscle temperature and thermal sensation (P < 0.05). Self-chosen pace was greater with CHOc (12.5 ± 0.5 km h(-1)) compared with CHO (11.3 ± 0.4 km h(-1)), PLA (11.3 ± 0.4 km h(-1)) and PLAc (11.6 ± 0.5 km h(-1)) (P < 0.05). High-intensity exercise capacity was improved with CHOc and CHO when compared with PLA (CHOc; 79.8 ± 7 s, CHO; 72.1 ± 5 s, PLAc; 70.1 ± 8 s, PLA; 57.1 ± 5 s; P < 0.05). Mental concentration during the protocol was also enhanced during CHOc compared with PLA (P < 0.05). These results suggest pre-cooling in conjunction with the ingestion of carbohydrate during exercise enhances exercise capacity and helps maintain mental performance during intermittent exercise in hot conditions.

  20. Multi-objective Aerodynamic and Stealthy Performance Optimization for Large- aspect- ratio Forward- swept Wings%大展弦比前掠翼气动隐身多目标优化

    Institute of Scientific and Technical Information of China (English)

    廖炎平; 刘莉; 龙腾

    2011-01-01

    Forward- Swept wing (FSW) configuration provides a now direction for the aerodynamic configuration desigu of UAV benause its excellent aerodynamic characteristics. The Class-Shape function Transformation (CST) method is used to describe the parameterized airfoil geometry. The parameterized models for aerodynamic and stealthy performance of FSW are constructed. The aerodynamic analysis model of FSW is constructed by computational fluid dynamics method basod on N - S equations. Tbe stealthy performance analysis model of FSW is constructed by computational electromagnetics method based Method of Moments ( MoM ). The multi - objective aerodynamic and stealthy performance optimization method for FSW using Kriging model is presented. The Latin hypercube method is employed to get a set of sample points. The aerodynamic and stealthy perfomance Kriging models are built. The multi-objective aerodynamic and stealthy performance optimization of FSW is optimized by combining Pareto genetic algorithm with Krigthg model. The results of the investigation show that the constructed analysis models are reasonable and the presented multi- objective optimization design method is feasible ,which can improve the performance of large- aspect- ratio FSW and the efficiency of optimization effiectively.%前掠翼布局优越的气动性能为无人机气动布局设计提供了一条新的方向.采用CST方法对翼型几何外形进行参数化描述,实现前掠翼气动和隐身多学科优化设计模型的参数化描述.建立了基于N-S方程的计算流体力学方法的前掠翼气动分析模型和基于矩量法的计算电磁学方法的前掠翼隐身分析模型.提出了基于Kriging模型的前掠翼气动隐身多目标优化方法,采用拉丁超方试验设计方法获取样本点,建立前掠翼气动和隐身的Kriging代理模型.将Pareto多目标遗传算法与Kriging代理模型结合进行大展弦比前掠翼的气动隐身多目标优化设计.研究结果表

  1. Comments on Ionization Cooling Channel Characteristics

    OpenAIRE

    Neuffer, David

    2013-01-01

    Ionization cooling channels with a wide variety of characteristics and cooling properties are being developed. These channels can produce cooling performances that are largely consistent with the ionization cooling theory developed previously. In this paper we review ionization cooling theory, discuss its application to presently developing cooling channels, and discuss criteria for optimizing cooling.

  2. Design and performance test of miniature capillary pumped loop for electronics cooling

    Institute of Scientific and Technical Information of China (English)

    万珍平; 皮丕辉; 付永清; 汤勇

    2008-01-01

    Considering two characteristics of compact heat dissipation room and high heat flux, a novel miniature capillary pumped loop (MCPL) for electronics cooling was proposed. MCPL consists of evaporator, condenser, vapor and liquid line dissipates heat by boiling and condensation of working fluids with no extra power consumption. Working fluid circulation is ensured by vapor pressure and capillary head. Saturated wick screens vapor and liquid, and ensures one-way flow of working fluid with no extra valve. In order to promote heat dissipation capacity of MCPL, the intensified boiling and condensation structures are embedded into evaporator and condenser respectively, which are useful to increasing boiling and condensation efficiency. Startup and run characteristics are tested by experiments in the condition of different power inputs and working fluids. MCPL is capable of dissipating 80 W of thermal energy and keeping the bottom substrate temperature of evaporator at 80 ℃.

  3. Transient performance and intelligent combination control of a novel spray cooling loop system

    Institute of Scientific and Technical Information of China (English)

    Wang Jin; Li Yunze; Wang Jun

    2013-01-01

    Effective thermal control systems are essential for the reliable working of insulated gate bipolar transistors (IGBTs) in many applications. A novel spray cooling loop system with inte-grated sintered porous copper wick (SCLS-SPC) is proposed to meet the requirements of higher device level heat fluxes and the harsh environments in some applications such as hybrid, fuel cell vehicles and aerospace. Fuzzy logic and proportional-integral-derivative (PID) policies are applied to adjust the electronic temperature within a safe working range. To evaluate the thermal control effect, a mathematical model of a 4-node thermal network and pump are established for predicting the dynamics of the SCLS-SPC. Moreover, the transient response of the 4 nodes and vapor mass flowrate under no control, PID and Fuzzy-PID are numerically investigated and discussed in detail.

  4. Optimizing x-ray mirror thermal performance using variable length cooling for second generation FELs

    Science.gov (United States)

    Hardin, Corey L.; Srinivasan, Venkat N.; Amores, Lope; Kelez, Nicholas M.; Morton, Daniel S.; Stefan, Peter M.; Nicolas, Josep; Zhang, Lin; Cocco, Daniele

    2016-09-01

    The success of the LCLS led to an interest across a number of disciplines in the scientific community including physics, chemistry, biology, and material science. Fueled by this success, SLAC National Accelerator Laboratory is developing a new high repetition rate free electron laser, LCLS-II, a superconducting linear accelerator capable of a repetition rate up to 1 MHz. Undulators will be optimized for 200 to 1300 eV soft X-rays, and for 1000 to 5000 eV hard X-rays. To absorb spontaneous radiation, higher harmonic energies and deflect the x-ray beam to various end stations, the transport and diagnostics system includes grazing incidence plane mirrors on both the soft and Hard X-ray beamline. To deliver the FEL beam with minimal power loss and wavefront distortion, we need mirrors of height errors below 1nm rms in operational conditions. We need to mitigate the thermal load effects due to the high repetition rate. The absorbed thermal profile is highly dependent on the beam divergence, and this is a function of the photon energy. To address this complexity, we developed a mirror cradle with variable length cooling and first order curve correction. Mirror figure error is minimized using variable length water-cooling through a gallium-indium eutectic bath. Curve correction is achieved with an off-axis bender that will be described in details. We present the design features, mechanical analysis and results from optical and mechanical tests of a prototype assembly, with particular regards to the figure sensitivity to bender corrections.

  5. Performance evaluation of Iranian cooling vest on the physiological indices in hot climatic chamber

    Science.gov (United States)

    Dehghan, Habibollah; Gharehbaei, Somayeh; Mahaki, Behzad

    2016-01-01

    Background: Heat stress is a threat to those who work in high temperatures. The purpose in this study was an examination of the cooling ability of Iranian phase change material (PCM) cold vest in hot and dry conditions in a climatic chamber. Materials and Methods: This experimental study was implemented on 12 male students (age 23.7 ± 2.8 years, weight 66.1 ± 11.4 kg, and VO2 max 2.53 L/min) in 2013. The heat strain score index (HSSI), skin temperature and oral temperature, and heartbeat in two phases with and without cooling vest was measured during 30 min in a climatic chamber (temperature 38.8 ± 1.3°C humidity ratio 32.9 ± 2.3%) and in two activity intensity of 2.4 and 4.8 km/h speed on the treadmill, and the data differences between groups “with” and “without” vest were tested by t-test and repeated measurement. The level of significance was considered as 0.05. Results: The change in heartbeat at two activities, the oral temperature and heat strain score at 4.8 km/h, did not differ significantly between groups (with and without vest), as expected (P > 0.05). However, the change in skin temperature at two activities, oral temperature and heat strain score at 2.4 km/h, was significant between groups, as expected (P < 0.05). The average of skin temperature at 15th and 30th min during the experiment at two activities of 2.4 and 4.8 km/h was significant. Conclusion: The findings of the study indicated that using the Iranian PCM cold vest in hot and dry climate can affect the reduction of skin temperature, oral temperature, and HSSI in light activities. PMID:27500168

  6. Cooling via one hand improves physical performance in heat-sensitive individuals with Multiple Sclerosis: A preliminary study

    Directory of Open Access Journals (Sweden)

    Murray Julie

    2008-05-01

    Full Text Available Abstract Background Many individuals afflicted with multiple sclerosis (MS experience a transient worsening of symptoms when body temperature increases due to ambient conditions or physical activity. Resulting symptom exacerbations can limit performance. We hypothesized that extraction of heat from the body through the subcutaneous retia venosa that underlie the palmar surfaces of the hands would reduce exercise-related heat stress and thereby increase the physical performance capacity of heat-sensitive individuals with MS. Methods Ten ambulatory MS patients completed one or more randomized paired trials of walking on a treadmill in a temperate environment with and without cooling. Stop criteria were symptom exacerbation and subjective fatigue. The cooling treatment entailed inserting one hand into a rigid chamber through an elastic sleeve that formed an airtight seal around the wrist. A small vacuum pump created a -40 mm Hg subatmospheric pressure enviinside the chamber where the palmar surface of the hand rested on a metal surface maintained at 18–22°C. During the treatment trials, the device was suspended from above the treadmill on a bungee cord so the subjects could comfortably keep a hand in the device without having to bear its weight while walking on the treadmill. Results When the trials were grouped by treatment only, cooling treatment increased exercise durations by 33% (43.6 ± 17.1 min with treatment vs. 32.8 ± 10.9 min. without treatment, mean ± SD, p -6, paired t-test, n = 26. When the average values were calculated for the subjects who performed multiple trials before the treatment group results were compared, cooling treatment increased exercise duration by 35% (42.8 ± 16.4 min with treatment vs. 31.7 ± 9.8 min. without treatment, mean ± SD, p Conclusion These preliminary results suggest that utilization of the heat transfer capacity of the non-hairy skin surfaces can enable temperature-sensitive individuals with MS to

  7. Bat flight: aerodynamics, kinematics and flight morphology.

    Science.gov (United States)

    Hedenström, Anders; Johansson, L Christoffer

    2015-03-01

    Bats evolved the ability of powered flight more than 50 million years ago. The modern bat is an efficient flyer and recent research on bat flight has revealed many intriguing facts. By using particle image velocimetry to visualize wake vortices, both the magnitude and time-history of aerodynamic forces can be estimated. At most speeds the downstroke generates both lift and thrust, whereas the function of the upstroke changes with forward flight speed. At hovering and slow speed bats use a leading edge vortex to enhance the lift beyond that allowed by steady aerodynamics and an inverted wing during the upstroke to further aid weight support. The bat wing and its skeleton exhibit many features and control mechanisms that are presumed to improve flight performance. Whereas bats appear aerodynamically less efficient than birds when it comes to cruising flight, they have the edge over birds when it comes to manoeuvring. There is a direct relationship between kinematics and the aerodynamic performance, but there is still a lack of knowledge about how (and if) the bat controls the movements and shape (planform and camber) of the wing. Considering the relatively few bat species whose aerodynamic tracks have been characterized, there is scope for new discoveries and a need to study species representing more extreme positions in the bat morphospace.

  8. Cooling arrangement for a gas turbine component

    Science.gov (United States)

    Lee, Ching-Pang; Heneveld, Benjamin E

    2015-02-10

    A cooling arrangement (82) for a gas turbine engine component, the cooling arrangement (82) having a plurality of rows (92, 94, 96) of airfoils (98), wherein adjacent airfoils (98) within a row (92, 94, 96) define segments (110, 130, 140) of cooling channels (90), and wherein outlets (114, 134) of the segments (110, 130) in one row (92, 94) align aerodynamically with inlets (132, 142) of segments (130, 140) in an adjacent row (94, 96) to define continuous cooling channels (90) with non continuous walls (116, 120), each cooling channel (90) comprising a serpentine shape.

  9. Acoustic and aerodynamic performance of a 1.5-pressure-ratio, 1.83-meter (6 ft) diameter fan stage for turbofan engines (QF-2)

    Science.gov (United States)

    Woodward, R. P.; Lucas, J. G.; Balombin, J. R.

    1977-01-01

    The fan was externally driven by an electric motor. Design features for low-noise generation included the elimination of inlet guide vanes, long axial spacing between the rotor and stator blade rows, and the selection of blade-vane numbers to achieve duct-mode cutoff. The fan QF-2 results were compared with those of another full-scale fan having essentially identical aerodynamic design except for nozzle geometry and the direction of rotation. The fan QF-2 aerodynamic results were also compared with those obtained from a 50.8 cm rotor-tip-diameter model of the reverse rotation fan QF-2 design. Differences in nozzle geometry other than exit area significantly affected the comparison of the results of the full-scale fans.

  10. Assessment of Energy, Environmental and Economic Performance of a Solar Desiccant Cooling System with Different Collector Types

    Directory of Open Access Journals (Sweden)

    Giovanni Angrisani

    2014-10-01

    Full Text Available Desiccant-based air handling units can achieve reductions in greenhouse gas emissions and energy savings with respect to conventional air conditioning systems. Benefits are maximized when they interact with renewable energy technologies, such as solar collectors. In this work, experimental tests and data derived from scientific and technical literature are used to implement a model of a solar desiccant cooling system, considering three different collector technologies (air, flat-plate and evacuated collectors. Simulations were then performed to compare the energy, environmental and economic performance of the system with those of a desiccant-based unit where regeneration thermal energy is supplied by a natural gas boiler, and with those of a conventional air-handling unit. The only solution that allows achieving the economic feasibility of the solar desiccant cooling unit consists of 16 m2 of evacuated solar collectors. This is able to obtain, with respect to the reference system, a reduction of primary energy consumption and of the equivalent CO2 emissions of 50.2% and 49.8%, respectively, but with a payback time of 20 years.

  11. Performance simulation of the JPL solar-powered distiller. Part 1: Quasi-steady-state conditions. [for cooling microwave equipment

    Science.gov (United States)

    Yung, C. S.; Lansing, F. L.

    1983-01-01

    A 37.85 cu m (10,000 gallons) per year (nominal) passive solar powered water distillation system was installed and is operational in the Venus Deep Space Station. The system replaced an old, electrically powered water distiller. The distilled water produced with its high electrical resistivity is used to cool the sensitive microwave equipment. A detailed thermal model was developed to simulate the performance of the distiller and study its sensitivity under varying environment and load conditions. The quasi-steady state portion of the model is presented together with the formulas for heat and mass transfer coefficients used. Initial results indicated that a daily water evaporation efficiency of 30% can be achieved. A comparison made between a full day performance simulation and the actual field measurements gave good agreement between theory and experiment, which verified the model.

  12. Numerical Analysis of Supersonic Film Cooling in Supersonic Flow in Hypersonic Inlet with Isolator

    Directory of Open Access Journals (Sweden)

    Silong Zhang

    2014-02-01

    Full Text Available Supersonic film cooling is an efficient method to cool the engine with extremely high heat load. In order to study supersonic film cooling in a real advanced engine, a two-dimensional model of the hypersonic inlet in a scramjet engine with supersonic film cooling in the isolator is built and validated through experimental data. The simulation results show that the cooling effect under different coolant injection angles does not show clear differences; a small injection angle can ensure both the cooling effect and good aerodynamic performances (e.g., flow coefficient of the hypersonic inlet. Under selected coolant injection angle and inlet Mach number, the cooling efficiency increases along with the injection Mach number of the coolant flow, only causing a little total pressure loss in the isolator. Along with the increase of the inlet Mach number of the hypersonic inlet, the cooling efficiency does not present a monotonic change because of the complex shock waves. However, the wall temperature shows a monotonic increase when the inlet Mach number increases. The mass flow rate of coolant flow should be increased to cool the engine more efficiently according to the mass flow rate of the main stream when the inlet Mach number increases.

  13. NUMERICAL INVESTIGATION OF THE ADVERSE EFFECT OF WIND ON THE HEAT TRANSFER PERFORMANCE OF TWO NATURAL DRAFT COOLING TOWERS IN TANDEM ARRANGEMENT

    Institute of Scientific and Technical Information of China (English)

    符松; 翟志强

    2001-01-01

    This article reports the findings on the adverse effect of the crosswind on the performance of natural draft cooling towers through numerical computation with the k-ε eddy-viscosity turbulence model. It is observed here that the cause of the adverse effect of the crosswind on the cooling towers can be attributed to the around flow effect which destroys the radial inflow into the cooling towers when the wind is absent. Hence, a significant deterioration in the heat transfer from the heat exchangers at lateral sides occurs.

  14. Numerical Simulation on Aerodynamic Performance of Steam Turbine Exhaust Hood Coupling Last Stage Blade%耦合末级叶片的汽轮机排汽缸气动数值模拟

    Institute of Scientific and Technical Information of China (English)

    史立群; 杨建道; 杨锐; 彭泽瑛

    2011-01-01

    为研究末级叶片出口流场径向的不均匀性对排汽缸气动性能的影响,基于稳态的三维N—S方程、能量方程以及连续性方程,采用商业CFD软件进行了排汽缸气动性能的数值模拟计算.结果表明:耦合末级叶片的数值模拟计算结果更接近真实值;动叶叶顶漏气射流对排汽缸内的流动结构有很大影响,使得计算得出的静压恢复系数有所增加;叶片叶顶漏气影响不可忽略,在今后的排汽缸气动设计及优化工作中需要考虑末级叶片的影响;排汽缸进口条件对于其气动性能有着决定性的影响.%In order to study the influence of flow field non--uniformity at last blade exit of steam turbine on aerodynamic performance of its exhaust hood, a numerical simulation has been carried to analyze the aerodynamic performance based on 3D steady-state N-S and energy and continuity equations using commercial CFD software. Results show that the numerical simulation coupling last stage blade works out a result closer to the true value; the leakage jet at blade tip has a significant impact on flow field in the exhaust hood, which generally results in increased recovery coefficient of calculated static pressure; the effect of tip leakage cafft be neglected in future design and optimization concerning aerodynamic performance of the exhaust hood; the inlet condition of exhaust hood affects the aerodynamic performance decisively.

  15. Aerodynamic performance of 0.5 meter-diameter, 337 meter-per-second tip speed, 1.5 pressure-ratio, single-stage fan designed for low noise aircraft engines

    Science.gov (United States)

    Gelder, T. F.; Lewis, G. W., Jr.

    1974-01-01

    Overall and blade-element aerodynamic performance of a 0.271-scale model of QF-1 are presented, examined, and then compared and evaluated with that from similar low noise fan stage designs. The tests cover a wide range of speeds and weight flows along with variations in stator setting angle and stator axial spacing from the rotor. At design speed with stator at design setting angle and a fixed distance between stage measuring stations, there were no significant effects of increasing the axial spacing between rotor stator from 1.0 to 3.5 rotor chords on stage overall pressure ratio, efficiency or stall margin.

  16. Effect of nanofluid on thermal performance of heat pipe with two evaporators; application to satellite equipment cooling

    Science.gov (United States)

    Mashaei, P. R.; Shahryari, M.

    2015-06-01

    A study on the behavior of nanofluid in a cylindrical heat pipe with two heat sources is performed to analyze the nanofluid application in heat-dissipating satellite equipment cooling. Pure water, Al2O3-water and TiO2-water nanofluids are used as working fluids. An analytical modeling is presented to predict the wall temperature profile for the heat pipe assuming saturated vapor and conduction heat transfer for porous media and wall, respectively. The effects of particle concentration levels (φ=0 (distilled water), 2, 4, and 8%), particle diameters (dp=10, 20, and 40 nm) on the local wall temperature, heat transfer coefficient, thermal resistance, and the size of the heat pipe are investigated. It is observed that the better wall temperature uniformity can be achieved using nanofluid which results in lower temperature difference between evaporators and condenser sections. Results reveal that applying nanoparticle with smaller size and higher concentration level increases heat transfer coefficient remarkably by reducing thermal resistance of saturated porous media. It is also found that the presence of nanoparticles in water can lead to a reduction in weight of heat pipe, and thus satellite, under nearly identical condition. The findings of this paper prove the potential of nanofluid in satellite equipment cooling application.

  17. Influence of Icing on Bridge Cable Aerodynamics

    DEFF Research Database (Denmark)

    Koss, Holger; Frej Henningsen, Jesper; Olsen, Idar

    2013-01-01

    In recent years the relevance of ice accretion for wind-induced vibration of structural bridge cables has been recognised and became a subject of research in bridge engineering. Full-scale monitoring and observation indicate that light precipitation at moderate low temperatures between zero and -5......°C may lead to large amplitude vibrations of bridge cables under wind action. For the prediction of aerodynamic instability quasi-steady models have been developed estimating the cable response magnitude based on structural properties and aerodynamic force coefficients for drag, lift and torsion....... The determination of these force coefficients require a proper simulation of the ice layer occurring under the specific climatic conditions, favouring real ice accretion over simplified artificial reproduction. The work presented in this paper was performed to study the influence of ice accretion on the aerodynamic...

  18. Cable Aerodynamic Control

    DEFF Research Database (Denmark)

    Kleissl, Kenneth

    to a categorization of the different control technics together with an identification of two key mechanisms for reduction of the design drag force. During this project extensive experimental work examining the aerodynamics of the currently used cable surface modifications together with new innovative proposals have...

  19. Evaluation of the performance of the systems cooling auxiliary of the Almaraz NPP turbine building; Evaluacion del rendimiento de los sistemas de refrigeracion auxiliar del edificio de turbinas de CNA

    Energy Technology Data Exchange (ETDEWEB)

    Vilar Carmona, G.

    2011-07-01

    After the successive performance improvements, to evacuate the thermal loads, and maintain acceptable temperatures throughout the year, added an auxiliary cooling system of the building of turbine, TCA system, composed of 5 shot forced by unit cooling towers.

  20. Numerical Modeling and Analysis of Grooved Surface Applied to Film Cooling

    Institute of Scientific and Technical Information of China (English)

    L. Guo; Z. C. Liu; Y.Y.Yan; Z.W.Han

    2011-01-01

    In order to improve the efficiency of film cooling,numerical investigation was carried out to study the effects of different film-cooled plates on surface heat transfer.Both grooved and non-grooved surfaces were concerned.The modeling was performed using Fluent software with the adoption of Shear-Stress Transport (SST) k-co model as the turbulence closure.The coolant was supplied by a single film cooling hole with an inclination angle of 30°.The Mach numbers for the coolant flow and the mainstream flow were fixed at 0 and 0.6,respectively.At three blowing ratios of 0.5,1.0 and 1.5,the aerodynamic behaviour of the mixing process as well as the heat transfer performance of the film cooling were presented.The numerical results were validated using experimental data extracted from a benchmark test.Good agreements between numerical results and the experimental data were observed.For the film cooling efficiency,it shows that both local and laterally averaged cooling effectiveness can be improved by the non-smooth surface at different blowing ratios.Using the grooved surface,the turbulence intensity upon the plate can be reduced notably,and the mixing between the two flows is weakened due to the reduced turbulence level.The results indicate that the cooling effectiveness of film cooling can be enhanced by applying the grooved surface.

  1. 经纬网络充气机翼构形特征与气动性能分析%Analysis of configuration characteristics and aerodynamic performance on longitude-latitude network inflatable wings

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    The inflatable wing is a good innovational conception for the near space solar-powered aircraft.The problems of configuration characteristics and aerodynamic analysis of inflatable wings were taken as the aim of the current study.First,configuration characteristics were analyzed and designed.Then the model of 3d network inflatable wing was developed.With computational fluid dynamics method,aerodynamic performances of 2d inflatable wing profile and 3d network inflatable wing were studied.Numerical simulation result shows that the aerodynamic performances of2d inflatable wing profile and 3d network inflatable wing have reduced slightly at the design Reynolds number.Meanwhile,with the structure of flow field and mechanism analysis,the reason for the total drag coefficients of inflatable wings increasing significantly lies in that,in those bumpy areas of the inflatable wing,vortexes which cause the friction drag has a reduction in some extent,but the pressure drag has a significant increase,so the total aerodynamic performance decreases.%将充气机翼应用于临近空间太阳能飞行器是具有创新性的设计概念。针对充气机翼构形特征和气动分析的相关问题,对构形特征进行分析和设计,并建立经纬网络充气机翼的模型;进一步运用数值方法,通过与标准翼型对比,分析二维充气机翼、三维经纬网络充气机翼的气动性能。数值分析结果表明,在设计的雷诺数条件下,充气机翼的气动性能相比于标准翼型有所降低。在此基础上,结合对流场结构和流动机理的研究,分析出导致充气机翼总阻力系数明显增加的主要原因是:充气机翼表面许多凹陷的局部区域所形成的涡结构,导致局部的摩阻有小幅的减小,但压差阻力大幅增加,最终使得总的气动性能有所降低。

  2. Detectors with Improved Near-to-Mid IR Performance and Reduced Cooling Requirements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This STTR Phase I proposal addresses a NASA need for improved near-to-mid IR detectors for imaging and spectroscopy. High performance IR detectors with cutoff...

  3. 大型汽轮机低压排汽缸气动分析研究%Aerodynamic Performance AnaIysis of LP Exhaust Hood for Large Power Steam Turbine

    Institute of Scientific and Technical Information of China (English)

    江生科; 彭英杰

    2014-01-01

    Aerodynamic performance of the LP exhaust hood influenced power and efficiency of the steam turbine. Numerical anal-ysis for single cylinder and LP last stage coupling with exhaust hood showed that the exit flow field's inhomogeneity and pre-swirl of last stage blade affected the aerodynamic performance of LP exhaust hood. Design of LP exhaust hood with high performance should consider the interaction of the last stage and flow field of LP exhaust hood.%低压排汽缸的气动性能影响汽轮机组的功率和效率。文章对单独排汽缸和汽轮机低压末级整圈与排汽缸耦合进行了数值分析对比,发现汽轮机末级动叶出口流场的不均匀性和强烈的预旋影响低压排汽缸的气动性能。高性能的低压排汽缸设计应该考虑末级与低压排汽缸流场之间的相互作用。

  4. Leading Edge Device Aerodynamic Optimization

    Directory of Open Access Journals (Sweden)

    Marius Gabriel COJOCARU

    2015-12-01

    Full Text Available Leading edge devices are conventionally used as aerodynamic devices that enhance performances during landing and in some cases during takeoff. The need to increase the efficiency of the aircrafts has brought the idea of maintaining as much as possible a laminar flow over the wings. This is possible only when the leading edge of the wings is free from contamination, therefore using the leading edge devices with the additional role of shielding during takeoff. Such a device based on the Krueger flap design is aerodynamically analyzed and optimized. The optimization comprises three steps: first, the positioning of the flap such that the shielding criterion is kept, second, the analysis of the flap size and third, the optimization of the flap shape. The first step is subject of a gradient based optimization process of the position described by two parameters, the position along the line and the deflection angle. For the third step the Adjoint method is used to gain insight on the shape of the Krueger flap that will extend the most the stall limit. All these steps have been numerically performed using Ansys Fluent and the results are presented for the optimized shape in comparison with the baseline configuration.

  5. Continuous Aerodynamic Modelling of Entry Shapes

    NARCIS (Netherlands)

    Dirkx, D.; Mooij, E.

    2011-01-01

    During the conceptual design phase of a re-entry vehicle, the vehicle shape can be varied and its impact on performance evaluated. To this end, the continuous modeling of the aerodynamic characteristics as a function of the shape is useful in exploring the full design space. Local inclination method

  6. Measured Cooling Performance and Potential for Buried Duct Condensation in a 1991 Central Florida Retrofit Home

    Energy Technology Data Exchange (ETDEWEB)

    Chasar, D.; Withers, C.

    2013-02-01

    FSEC conducted energy performance monitoring of two existing residences in Central Florida that were undergoing various retrofits. These homes were occupied by FSEC researchers and were fully instrumented to provide detailed energy, temperature, and humidity measurements. The data provided feedback about the performance of two levels of retrofit in two types of homes in a hot-humid climate. This report covers a moderate-level retrofit and includes two years of pre-retrofit data to characterize the impact of improvements. The other home is a 'deep energy retrofit' (detailed in a separate report) that has performed at near zero energy with a photovoltaic (PV) system and extensive envelope improvements.

  7. EFFECT OF GASOLINE - ETHANOL BLENDS ON PERFORMANCE AND EMISSION CHARACTERISTICS OF A SINGLE CYLINDER AIR COOLED MOTOR BIKE SI ENGINE

    Directory of Open Access Journals (Sweden)

    A. SAMUEL RAJA

    2015-12-01

    Full Text Available This paper investigates the effect of using gasoline-ethanol (GE blends on performance and exhaust emission of a four stroke 150 cc single cylinder air cooled spark ignition (SI engine, without any modifications. Experiments were conducted at part load and different engine speeds ranging from 3000 to 5000 rpm, without and with catalytic converter. Ethanol content was varied from 5 percentage to 20 percentage by volume and four different blends (E5, E10, E15 and E20 were tested. Fuel consumption, engine speed, air fuel ratio, exhaust gas temperature and exhaust emissions were measured during each experiment. Brake thermal efficiency (ηb,th, volumetric efficiency (ηvol, brake specific fuel consumption (BSFC and excess air factor were calculated for each test run. Brake specific fuel consumption, volumetric efficiency and excess air factor increased with ethanol percentage in the blend. Carbon monoxide (CO, hydrocarbon (HC and oxides of nitrogen (NOx emissions decreased with blends.

  8. Performance of radiant cooling ceiling combined with personalized ventilation in an office room: identification of thermal conditions

    DEFF Research Database (Denmark)

    Lipczynska, Aleksandra; Kaczmarczyk, Jan; Melikov, Arsen Krikor

    2014-01-01

    The paper compares thermal environment conditions created by four HVAC systems: mixing ventilation, chilled ceiling combined with mixing ventilation, chilled ceiling with mixing ventilation and personalized ventilation, and chilled ceiling combined with personalized ventilation only. Measurements...... were performed in a test room arranged as an office with 2 workstations and 2 seating occupants resembled by thermal manikins. Heat gain of 66-72 W/m2 was simulated in the room (occupants, computers, lighting, solar gain). The air temperature in the chamber was maintained at 26°C and 28°C. Personalized...... ventilation supplied air at non-isothermal condition with temperature of 25°C. Results showed that the compared methods generated almost the same thermal environment in the occupied zone. However at the workstations the personalized ventilation combined with chilled ceiling provided more cooling and decreased...

  9. Performance investigation of the capric and lauric acid mixture as latent heat storage for a cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Dimaano, M.N.R. [University of Santo Tomas, Manila (Philippines). Faculty of Engineering; Watanabe, Takayuki [Tokyo Institute of Technology (Japan). Research Laboratory for Nuclear Reactors

    2002-07-01

    The thermal performance of the capric acid and lauric acid mixture (C-L acid) in the respective composition of 65% and 35% by mole was investigated for its cooling capacity. Pentadecane was used for comparison. A vertical cylindrical storage capsule was employed for the study. The temperature distribution of the C-L acid during charging and discharging inside a vertical tube was experimentally determined in both radial and axial directions. A melting point of 18-19.5{sup o}C was observed. This value corroborates with the DSC-obtained values for the C-L acid. The calculated stored energy based on the radial temperature distribution during charge and discharge processes indicates that the C-L acid is a potential latent heat storage material. (author)

  10. Solar heating and cooling experiment for a school in Atlanta: performance report. [George A. Towns Elementary School

    Energy Technology Data Exchange (ETDEWEB)

    1977-08-01

    This report documents the performance, and conclusions therefrom, of a 13 month period of monitoring the performance of the experimental solar heating and cooling system installed in the George A. Towns Elementary School, Atlanta, Georgia. The solar collector system involves 10,360 ft/sup 2/ of PPG ''Baseline'' flat-plate collectors with an ALCOA selective coating, augmented by 10,800 square feet of aluminized Mylar reflectors. Three 15,000 gallon steel storage tanks, a 100-ton Arkla absorption chiller together with its cooling tower, a collector gravity drain system with a 1,600 gallon holding tank and a collector nitrogen purge system, six pumps and 26 pneumatic control valves were installed and interfaced with the pre-existing gas furnace and distribution system. In the winter heating mode, the solar energy is stored in all three tanks, total capacity of 45,000 gallons, between design temperatures of 105/sup 0/ to 140/sup 0/F. As soon as Tank 1 is brought up to 140/sup 0/F, the control valves isolate it from the collector loop, and the hot water from the collectors is used to charge Tanks 2 and then Tank 3. Water can be drawn from Tank 1 to heat the school while Tanks 2 and 3 are being charged. As a consequence of the flexibility provided by the three tanks, compared to a single tank of equivalent capacity, the thermal lag in the system is reduced. A variable speed pump, in response to sensors at the inlet and outlet of the collectors, modulates the flow of water through each collector from a maximum of .5 gpm to a minimum of .1 gpm, attempting to maintain a temperature rise of about 10/sup 0/F. In the summer cooling mode, storage tanks 2 and 3 are designed to store hot water at temperatures between 180/sup 0/ to 200/sup 0/F, and tank 1 is used to store chilled water. (WHK)

  11. Characteristic Evaluation on the Cooling Performance of an Electrical Air Conditioning System Using R744 for a Fuel Cell Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Moo-Yeon Lee

    2012-05-01

    Full Text Available The objective of this study was to investigate the cooling performance characteristics of an electrical air conditioning system using R744 as an alternative of R-134a for a fuel cell electric vehicle. In order to analyze the cooling performance characteristics of the air conditioning system using R744 for a fuel cell electric vehicle, an electrical air conditioning system using R744 was developed and tested under various operating conditions according to both inlet air conditions of the gas cooler and evaporator and compressor speed. The cooling capacity and coefficient of performance (COP forcooling of the tested air conditioning system were up to 6.4 kW and 2.5, respectively. In addition, the electrical air conditioning system with R744 using an inverter driven compressor showed better performance than the conventional air conditioning system with R-134a under the same operating conditions. The observed cooling performance of the developed electrical air conditioning system was found to be sufficient for cooling loads under various real driving conditions for a fuel cell electric vehicle.

  12. Animal performance and economic comparison of novel and toxic endophyte tall fescues to cool-season annuals.

    Science.gov (United States)

    Beck, P A; Gunter, S A; Lusby, K S; West, C P; Watkins, K B; Hubbell, D S

    2008-08-01

    Increased costs of annual establishment of small grain pasture associated with fuel, machinery, and labor are eroding the profitability of stocker cattle enterprises. Interest has therefore increased in development of cool-season perennial grasses that are persistent and high quality. This study occurred on 24 ha (divided into thirty 0.81-ha paddocks) located at the University of Arkansas Division of Agriculture Livestock and Forestry Branch Station, near Batesville. Two tall fescue (Festuca arundinacea Schreb.) cultivars infected with novel endophytes (NE), Jesup infected with AR542 endophyte (Jesup AR542), and HiMag infected with Number 11 endophyte (HM11) were established in September 2002. Jesup AR542 and HM11 were compared with endemic endophyte Kentucky 31 (KY-31) tall fescue; wheat (Triticum aestivum L.) and cereal rye (WR, Secale cereale L.) planted in September 2003, 2004, and 2005; and annual ryegrass [RG, Lolium perenne L. ssp. multiflorum (Lam.) Husnot] planted in September 2004 and 2005. Each year, 3 steers (3.7 steers/ha) were placed on each pasture for fall and winter grazing, and 5 steers (6.2 steers/ha) were placed on each pasture for spring grazing. Animal performance is presented by year in the presence of a year x treatment interaction (P or = 0.14). Body weight gain per hectare was least (P < 0.01) for steers grazing KY-31. Average net return of NE tall fescue was greater (P < 0.01) than KY-31, but profitability of NE did not consistently differ from cool-season annuals. Across the 3-yr study, NE tall fescue produced net returns per hectare of $219; this level of profitability would require 4 yr for a new planting of NE tall fescue to break even. Novel endophyte tall fescues offer potential benefits related to decreased risk of stand establishment of annual forage crops, longer growing season, and acceptable animal performance.

  13. Heat acclimatization does not improve VO2max or cycling performance in a cool climate in trained cyclists

    DEFF Research Database (Denmark)

    Karlsen, Anders; Racinais, S; Jensen, M V;

    2015-01-01

    This study investigated if well-trained cyclists improve V ˙ O 2 m a x and performance in cool conditions following heat acclimatization through natural outdoor training in hot conditions. Eighteen trained male cyclists were tested for physiological adaptations, V ˙ O 2 m a x , peak aerobic power...... was associated with marked improvements in TT performance in the heat. However, for the well-trained endurance athletes, this did not transfer to an improved aerobic exercise capacity or outdoor TT performance in cool conditions....

  14. Cognitive, Psychomotor, and Physical Performance in Cold Air After Cooling by Exercise in Cold Water

    Science.gov (United States)

    2007-06-01

    Saybrook, CT) were at- tached at 11 skin sites: foot, calf, anterior thigh, abdo- men, chest, triceps, anterior aspect of the forearm, sub- scapular ...muscle strength, slows nerve conduction velocity, and reduces joint mobility (8), all of which may have contributed to decreased step test performance

  15. Performance analysis on a solar-powered air-cooled two-staged water ejector cooling system%风冷太阳能双级水喷射制冷空调系统性能分析

    Institute of Scientific and Technical Information of China (English)

    卢苇; 郑立星; 陈洪杰

    2011-01-01

    The performance was analyzed for a solar-powered air-cooled two-staged water ejector cooling system that rated cooling capacity is 12.3 Kw. The cooling capacity of the proposed system increases with the rising of indoor temperature and the enhancement of solar irradiance, while decreases with the rising of the ambient temperature. The COP has similar changing trend with that of the cooling capacity except that it increases rapidly with the enhancement of solar irradiance firstly and then become stable when the solar irradiance exceeding a certain value. The cooling capacity is 7.7~32 Kw and the COP is 0.082~0.107 under the normal operating conditions with indoor temperature over 27℃, ambient temperature below 38 ℃. And solar irradiance surpassing 500 W/m2.%对额定制冷量为12.3kW的风冷太阳能双级水喷射制冷空调系统进行了变工况性能分析.该系统的制冷量随室内温度升高而增大,随环境温度升高而减小,随太阳辐照度增强而增大;COP的变化与制冷量的变化类似,所不同的是COP随着太阳辐照度的增强先迅速增大,当太阳辐照度增大到一定程度后,COP基本保持稳定.在室内温度不低于27℃,室外温度不高于38℃,太阳辐照度不低于500 W/m2的条件下,系统的制冷量为7.7~32 kW,COP为0.082~0.107.

  16. Retrofit device to improve vapor compression cooling system performance by dynamic blower speed modulation

    Science.gov (United States)

    Roth, Robert Paul; Hahn, David C.; Scaringe, Robert P.

    2015-12-08

    A device and method are provided to improve performance of a vapor compression system using a retrofittable control board to start up the vapor compression system with the evaporator blower initially set to a high speed. A baseline evaporator operating temperature with the evaporator blower operating at the high speed is recorded, and then the device detects if a predetermined acceptable change in evaporator temperature has occurred. The evaporator blower speed is reduced from the initially set high speed as long as there is only a negligible change in the measured evaporator temperature and therefore a negligible difference in the compressor's power consumption so as to obtain a net increase in the Coefficient of Performance.

  17. Retrofit device to improve vapor compression cooling system performance by dynamic blower speed modulation

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Robert Paul; Hahn, David C.; Scaringe, Robert P.

    2015-12-08

    A device and method are provided to improve performance of a vapor compression system using a retrofittable control board to start up the vapor compression system with the evaporator blower initially set to a high speed. A baseline evaporator operating temperature with the evaporator blower operating at the high speed is recorded, and then the device detects if a predetermined acceptable change in evaporator temperature has occurred. The evaporator blower speed is reduced from the initially set high speed as long as there is only a negligible change in the measured evaporator temperature and therefore a negligible difference in the compressor's power consumption so as to obtain a net increase in the Coefficient of Performance.

  18. Comparative Cooling Season Performance of Air Distribution Systems in Multistory Townhomes

    Energy Technology Data Exchange (ETDEWEB)

    Poerschke, A. [IBACOS, Inc., Pittsburgh, PA (United States); Beach, R. [IBACOS, Inc., Pittsburgh, PA (United States); Beggs, T. [IBACOS, Inc., Pittsburgh, PA (United States)

    2016-08-26

    IBACOS investigated the performance of a small-diameter high velocity heat pump system compared to a conventional system in a new construction triplex townhouse. A ductless heat pump system also was installed for comparison, but the homebuyer backed out because of aesthetic concerns about that system. In total, two buildings, having identical solar orientation and comprised of six townhomes, were monitored for comfort and energy performance. Results show that the small-diameter system provides more uniform temperatures from floor to floor in the three-story townhome. No clear energy consumption benefit was observed from either system. The builder is continuing to explore the small-diameter system as its new standard system to provide better comfort and indoor air quality. The homebuilder also explored the possibility of shifting its townhome product to meet the U.S. Department of Energy Challenge Home National Program Requirements.

  19. Detailed performance and environmental monitoring of aquifer heating and cooling systems

    Science.gov (United States)

    Acuna, José; Ahlkrona, Malva; Zandin, Hanna; Singh, Ashutosh

    2016-04-01

    The project intends to quantify the performance and environmental impact of large scale aquifer thermal energy storage, as well as point at recommendations for operating and estimating the environmental footprint of future systems. Field measurements, test of innovative equipment as well as advanced modelling work and analysis will be performed. The following aspects are introduced and covered in the presentation: -Thermal, chemical and microbiological influence of akvifer thermal energy storage systems: measurement and evaluation of real conditions and the influence of one system in operation. -Follow up of energy extraction from aquifer as compared to projected values, recommendations for improvements. -Evaluation of the most used thermal modeling tool for design and calculation of groundwater temperatures, calculations with MODFLOW/MT3DMS -Test and evaluation of optical fiber cables as a way to measure temperatures in aquifer thermal energy storages

  20. Analysis of dashpot performance for rotating control drums of a lithium cooled fast reactor concept

    Science.gov (United States)

    Wenzler, C. J.

    1972-01-01

    A dashpot was incorporated in the design of the drive train of the rotating control drum to prevent shock damage to the control drum and drive train at the termination of a scram action. A rotating vane dashpot using reactor coolant lithium as a damping fluid appears to be the best candidate of the various damping devices explored. A performance analysis, results and discussion of vane type dashpots are presented.

  1. Investigation of the Performance of D2O-Cooled High-Conversion Reactors for Fuel Cycle Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Hikaru Hiruta; Gilles Youinou

    2013-09-01

    This report presents FY13 activities for the analysis of D2O cooled tight-pitch High-Conversion PWRs (HCPWRs) with U-Pu and Th-U fueled cores aiming at break-even or near breeder conditions while retaining the negative void reactivity. The analyses are carried out from several aspects which could not be covered in FY12 activities. SCALE 6.1 code system is utilized, and a series of simple 3D fuel pin-cell models are developed in order to perform Monte Carlo based criticality and burnup calculations. The performance of U-Pu fueled cores with axial and internal blankets is analyzed in terms of their impact on the relative fissile Pu mass balance, initial Pu enrichment, and void coefficient. In FY12, Pu conversion performances of D2O-cooled HCPWRs fueled with MOX were evaluated with small sized axial/internal DU blankets (approximately 4cm of axial length) in order to ensure the negative void reactivity, which evidently limits the conversion performance of HCPWRs. In this fiscal year report, the axial sizes of DU blankets are extended up to 30 cm in order to evaluate the amount of DU necessary to reach break-even and/or breeding conditions. Several attempts are made in order to attain the milestone of the HCPWR designs (i.e., break-even condition and negative void reactivity) by modeling of HCPWRs under different conditions such as boiling of D2O coolant, MOX with different 235U enrichment, and different target burnups. A similar set of analyses are performed for Th-U fueled cores. Several promising characteristics of 233U over other fissile like 239Pu and 235U, most notably its higher fission neutrons per absorption in thermal and epithermal ranges combined with lower ___ in the fast range than 239Pu allows Th-U cores to be taller than MOX ones. Such an advantage results in 4% higher relative fissile mass balance than that of U-Pu fueled cores while retaining the negative void reactivity until the target burnup of 51 GWd/t. Several other distinctions between U-Pu and

  2. THREE-DIMENSIONAL REGULARITIES OF DISTRIBUTION OF AIR-INLET CHARACTERISTIC VELOCITY IN NATURAL-DRAFT WET COOLING TOWER

    Institute of Scientific and Technical Information of China (English)

    WANG Kai; SUN Feng-zhong; ZHAO Yuan-bin; GAO Ming; SHI Yue-tao

    2008-01-01

    A model for heat and mass transfer in a natural-draft wet cooling tower was established. Numerical simulation with the k-ε turbulent model was conducted. Distribution rules of air inlet aerodynamic field were studied. Field experiments were done in a cooling tower in power plant, and the test data was compared with the related results. The definition of characteristic air velocity was proposed and its influencing factors, such as the cross-wind velocity and circumferential angle, were quantitatively studied. It can be used to evaluate the performance of cooling tower and to calculate the ventilation quantity and resistance of air inlet. It is also a theoretical basis for cooling tower design and performance optimization.

  3. Modeling and Simulation of Radiative Compressible Flows in Aerodynamic Heating Arc-Jet Facility

    Science.gov (United States)

    Bensassi, Khalil; Laguna, Alejandro A.; Lani, Andrea; Mansour, Nagi N.

    2016-01-01

    Numerical simulations of an arc heated flow inside NASA's 20 [MW] Aerodynamics heating facility (AHF) are performed in order to investigate the three-dimensional swirling flow and the current distribution inside the wind tunnel. The plasma is considered in Local Thermodynamics Equilibrium(LTE) and is composed of Air-Argon gas mixture. The governing equations are the Navier-Stokes equations that include source terms corresponding to Joule heating and radiative cooling. The former is obtained by solving an electric potential equation, while the latter is calculated using an innovative massively parallel ray-tracing algorithm. The fully coupled system is closed by the thermodynamics relations and transport properties which are obtained from Chapman-Enskog method. A novel strategy was developed in order to enable the flow solver and the radiation calculation to be preformed independently and simultaneously using a different number of processors. Drastic reduction in the computational cost was achieved using this strategy. Details on the numerical methods used for space discretization, time integration and ray-tracing algorithm will be presented. The effect of the radiative cooling on the dynamics of the flow will be investigated. The complete set of equations were implemented within the COOLFluiD Framework. Fig. 1 shows the geometry of the Anode and part of the constrictor of the Aerodynamics heating facility (AHF). Fig. 2 shows the velocity field distribution along (x-y) plane and the streamline in (z-y) plane.

  4. Heat Removal Performance of Hybrid Control Rod for Passive In-Core Cooling System

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Mo; Jeong, Yeong Shin; Kim, In Guk; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2015-10-15

    The two-phase closed heat transfer device can be divided by thermosyphon heat pipe and capillary wicked heat pipe which uses gravitational force or capillary pumping pressure as a driving force of the convection of working fluid. If there is a temperature difference between reactor core and ultimate heat sink, the decay heat removal and reactor shutdown is possible at any accident conditions without external power sources. To apply the hybrid control rod to the commercial nuclear power plants, its modelling about various parameters is the most important work. Also, its unique geometry is coexistence of neutron absorber material and working fluid in a cladding material having annular vapor path. Although thermosyphon heat pipe (THP) or wicked heat pipe (WHP) shows high heat transfer coefficients for limited space, the maximum heat removal capacity is restricted by several phenomena due to their unique heat transfer mechanism. Validation of the existing correlations on the annular vapor path thermosyphon (ATHP) which has different wetted perimeter and heated diameter must be conducted. The effect of inner structure, and fill ratio of the working fluid on the thermal performance of heat pipe has not been investigated. As a first step of the development of hybrid heat pipe, the ATHP which contains neutron absorber in the concentric thermosyphon (CTHP) was prepared and the thermal performance of the annular thermosyphon was experimentally studied. The heat transfer characteristics and flooding limit of the annular vapor path thermosyphon was studied experimentally to model the performance of hybrid control rod. The following results were obtained: (1) The annular vapor path thermosyphon showed better evaporation heat transfer due to the enhanced convection between adiabatic and condenser section. (2) Effect of fill ratio on the heat transfer characteristics was negligible. (3) Existing correlations about flooding limit of thermosyphon could not reflect the annular vapor

  5. Physical and perceptual cooling with beverages to increase cycle performance in a tropical climate.

    Directory of Open Access Journals (Sweden)

    Florence Riera

    Full Text Available PURPOSE: This study compares the effects of neutral temperature, cold and ice-slush beverages, with and without 0.5% menthol on cycling performance, core temperature (Tco and stress responses in a tropical climate (hot and humid conditions. METHODS: Twelve trained male cyclists/triathletes completed six 20-km exercise trials against the clock in 30.7°C±0.8°C and 78%±0.03% relative humidity. Before and after warm-up, and before exercise and every 5 km during exercise, athletes drank 190 mL of either aromatized (i.e., with 0.5 mL of menthol (5 gr/L or a non-aromatized beverage (neutral temperature: 23°C±0.1°C, cold: 3°C±0.1°C, or ice-slush: -1°C±0.7°C. During the trials, heart rate (HR was continuously monitored, whereas core temperature (Tco, thermal comfort (TC, thermal sensation (TS and rate of perceived exertion (RPE were measured before and after warm-up, every 5 km of exercise, and at the end of exercise and after recovery. RESULTS: Both the beverage aroma (P<0.02 and beverage temperature (P<0.02 had significant and positive effects on performance, which was considerably better with ice-slush than with a neutral temperature beverage, whatever the aroma (P<0.002, and with menthol vs non-menthol (P<0.02. The best performances were obtained with ice-slush/menthol and cold/menthol, as opposed to neutral/menthol. No differences were noted in HR and Tco between trials. CONCLUSION: Cold water or ice-slush with menthol aroma seems to be the most effective beverage for endurance exercise in a tropical climate. Further studies are needed to explore its effects in field competition.

  6. Mathematical modelling of the thermal performance of a phase-change material (PCM) store: cooling cycle

    Energy Technology Data Exchange (ETDEWEB)

    Kuerklue, A. [Akdeniz University, Faculty of Agriculture, Antalya (Turkey); Wheldon, A.; Hadley, P. [Reading Univ. (United Kingdom). Dept. of Engineering]|[Reading Univ. (United Kingdom). School of Plant Sciences

    1996-07-01

    A mathematical model for the prediction of the thermal performances of a PCM store containing 1 m long and 38 mm diameter polypropylene tube has been developed in this study. Air was utilised in the store as the heat transfer fluid. The model was based on an energy balance or the `conservation of energy principle`. The results indicate that the agreement between the predicted and observed temperature of heat transfer data is generally good. The amount of energy used in increasing the temperature of the PCM at any time during the phase- change process is predicted to be about 3.5% of the total energy stored. (Author)

  7. Development of a technique to evaluate the performance of cooling headers and its applications in POSCO plate mills

    Science.gov (United States)

    Kang, Jong-Hoon; Lee, Pil-Jong

    2016-03-01

    Hundreds of thousands of liquid jet nozzles are widely used in controling cooling equipment to accelerate the cooling of hot plates. The holes of these nozzles become clogged or the hole size becomes smaller as foreign substances like grease, scrap, and mud containing cooling water are flushed through. In this case, cooling water sprays abnormally through the partially clogged or restricted nozzle. This causes inhomogeneous cooling of hot plates. The objective of this study is to develop an evaluation system of cooling headers including nozzles. This paper presents the method to evaluate the conditions of spraying nozzles. The sensor developed in this research measures the liquid column of spraying nozzles using differential pressure between the inside sensor block and ambient air. In addition, the results of a field test in a real, large factory are introduced in this paper.

  8. Development of a technique to evaluate the performance of cooling headers and its applications in POSCO plate mills

    Directory of Open Access Journals (Sweden)

    Kang Jong-Hoon

    2016-01-01

    Full Text Available Hundreds of thousands of liquid jet nozzles are widely used in controling cooling equipment to accelerate the cooling of hot plates. The holes of these nozzles become clogged or the hole size becomes smaller as foreign substances like grease, scrap, and mud containing cooling water are flushed through. In this case, cooling water sprays abnormally through the partially clogged or restricted nozzle. This causes inhomogeneous cooling of hot plates. The objective of this study is to develop an evaluation system of cooling headers including nozzles. This paper presents the method to evaluate the conditions of spraying nozzles. The sensor developed in this research measures the liquid column of spraying nozzles using differential pressure between the inside sensor block and ambient air. In addition, the results of a field test in a real, large factory are introduced in this paper.

  9. Performance of low smeared density sodium-cooled fast reactor metal fuel

    Science.gov (United States)

    Porter, D. L.; Chichester, H. J. M.; Medvedev, P. G.; Hayes, S. L.; Teague, M. C.

    2015-10-01

    An experiment was performed in the Experimental Breeder Rector-II (EBR-II) in the 1990s to show that metallic fast reactor fuel could be used in reactors with a single, once-through core. To prove the long duration, high burnup, high neutron exposure capability an experiment where the fuel pin was designed with a very large fission gas plenum and very low fuel smeared density (SD). The experiment, X496, operated to only 8.3 at.% burnup because the EBR-II reactor was scheduled for shut-down at that time. Many of the examinations of the fuel pins only funded recently with the resurgence of reactor designs using very high-burnup fuel. The results showed that, despite the low smeared density of 59% the fuel swelled radially to contact the cladding, fission gas release appeared to be slightly higher than demonstrated in conventional 75%SD fuel tests and axial growth was about the same as 75% SD fuel. There were axial positions in some of the fuel pins which showed evidence of fuel restructuring and an absence of fission products with low melting points and gaseous precursors (Cs and Rb). A model to investigate whether these areas may have overheated due to a loss of bond sodium indicates that it is a possible explanation for the fuel restructuring and something to be considered for fuel performance modeling of low SD fuel.

  10. Comparative Cooling Season Performance of Air Distribution Systems in Multistory Townhomes

    Energy Technology Data Exchange (ETDEWEB)

    Poerschke, Andrew [IBACOS Inc., Pittsburgh, PA (United States); Beach, Rob [IBACOS Inc., Pittsburgh, PA (United States; Beggs, Timothy [IBACOS Inc., Pittsburgh, PA (United States

    2016-08-01

    IBACOS investigated the performance of a small-diameter high velocity heat pump system compared to a conventional system in a new construction triplex townhouse. A ductless heat pump system also was installed for comparison, but the homebuyer backed out because of aesthetic concerns about that system. In total, two buildings, having identical solar orientation and comprised of six townhomes, were monitored for comfort and energy performance. Results show that the small-diameter system provides more uniform temperatures from floor to floor in the three-story townhome. No clear energy consumption benefit was observed from either system. The builder is continuing to explore the small-diameter system as its new standard system to provide better comfort and indoor air quality. The homebuilder also explored the possibility of shifting its townhome product to meet the U.S. Department of Energy Challenge Home National Program Requirements. Ultimately, the builder decided that adoption of these practices would be too disruptive midstream in the construction cycle. However, the townhomes met the ENERGY STAR Version 3.0 program requirements.

  11. Experiment Investigation on Electrical and Thermal Performances of a Semitransparent Photovoltaic/Thermal System with Water Cooling

    OpenAIRE

    Guiqiang Li; Gang Pei; Ming Yang; Jie Ji

    2014-01-01

    Different from the semitransparent building integrated photovoltaic/thermal (BIPV/T) system with air cooling, the semitransparent BIPV/T system with water cooling is rare, especially based on the silicon solar cells. In this paper, a semitransparent photovoltaic/thermal system (SPV/T) with water cooling was set up, which not only would provide the electrical power and hot water, but also could attain the natural illumination for the building. The PV efficiency, thermal efficiency, and exergy ...

  12. Performance Analysis of Cool Roof, Green Roof and Thermal Insulation on a Concrete Flat Roof in Tropical Climate

    OpenAIRE

    Zingre, Kishor T.; Yang, Xingguo; Wan, Man Pun

    2015-01-01

    In the tropics, the earth surface receives abundant solar radiation throughout the year contributing significantly to building heat gain and, thus, cooling demand. An effective method that can curb the heat gains through opaque roof surfaces could provide significant energy savings. This study investigates and compares the effectiveness of various passive cooling techniques including cool roof, green roof and thermal insulation for reducing the heat gain through a flat concrete roof in tropic...

  13. Aerodynamic Leidenfrost effect

    Science.gov (United States)

    Gauthier, Anaïs; Bird, James C.; Clanet, Christophe; Quéré, David

    2016-12-01

    When deposited on a plate moving quickly enough, any liquid can levitate as it does when it is volatile on a very hot solid (Leidenfrost effect). In the aerodynamic Leidenfrost situation, air gets inserted between the liquid and the moving solid, a situation that we analyze. We observe two types of entrainment. (i) The thickness of the air gap is found to increase with the plate speed, which is interpreted in the Landau-Levich-Derjaguin frame: Air is dynamically dragged along the surface and its thickness results from a balance between capillary and viscous effects. (ii) Air set in motion by the plate exerts a force on the levitating liquid. We discuss the magnitude of this aerodynamic force and show that it can be exploited to control the liquid and even to drive it against gravity.

  14. Computational electromagnetic-aerodynamics

    CERN Document Server

    Shang, Joseph J S

    2016-01-01

    Presents numerical algorithms, procedures, and techniques required to solve engineering problems relating to the interactions between electromagnetic fields, fluid flow, and interdisciplinary technology for aerodynamics, electromagnetics, chemical-physics kinetics, and plasmadynamics This book addresses modeling and simulation science and technology for studying ionized gas phenomena in engineering applications. Computational Electromagnetic-Aerodynamics is organized into ten chapters. Chapter one to three introduce the fundamental concepts of plasmadynamics, chemical-physics of ionization, classical magnetohydrodynamics, and their extensions to plasma-based flow control actuators, high-speed flows of interplanetary re-entry, and ion thrusters in space exploration. Chapter four to six explain numerical algorithms and procedures for solving Maxwell’s equation in the time domain for computational electromagnetics, plasma wave propagation, and the time-dependent c mpressible Navier-Stokes equation for aerodyn...

  15. On cup anemometer rotor aerodynamics.

    Science.gov (United States)

    Pindado, Santiago; Pérez, Javier; Avila-Sanchez, Sergio

    2012-01-01

    The influence of anemometer rotor shape parameters, such as the cups' front area or their center rotation radius on the anemometer's performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal), tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a linear dependency of both calibration constants, the slope and the offset, on the cups' center rotation radius, the influence of the front area of the cups also being observed. The analytical model of Kondo et al. was proved to be accurate if it is based on precise data related to the aerodynamic behavior of a rotor's cup.

  16. On Cup Anemometer Rotor Aerodynamics

    Directory of Open Access Journals (Sweden)

    Santiago Pindado

    2012-05-01

    Full Text Available The influence of anemometer rotor shape parameters, such as the cups’ front area or their center rotation radius on the anemometer’s performance was analyzed. This analysis was based on calibrations performed on two different anemometers (one based on magnet system output signal, and the other one based on an opto-electronic system output signal, tested with 21 different rotors. The results were compared to the ones resulting from classical analytical models. The results clearly showed a linear dependency of both calibration constants, the slope and the offset, on the cups’ center rotation radius, the influence of the front area of the cups also being observed. The analytical model of Kondo et al. was proved to be accurate if it is based on precise data related to the aerodynamic behavior of a rotor’s cup.

  17. Cooling Performance Characteristics of the Stack Thermal Management System for Fuel Cell Electric Vehicles under Actual Driving Conditions

    Directory of Open Access Journals (Sweden)

    Ho-Seong Lee

    2016-04-01

    Full Text Available The cooling performance of the stack radiator of a fuel cell electric vehicle was evaluated under various actual road driving conditions, such as highway and uphill travel. The thermal stability was then optimized, thereby ensuring stable operation of the stack thermal management system. The coolant inlet temperature of the radiator in the highway mode was lower than that associated with the uphill mode because the corresponding frontal air velocity was higher than obtained in the uphill mode. In both the highway and uphill modes, the coolant temperatures of the radiator, operated under actual road driving conditions, were lower than the allowable limit (80 °C; this is the maximum temperature at which stable operation of the stack thermal management system of the fuel cell electric vehicle could be maintained. Furthermore, under actual road driving conditions in uphill mode, the initial temperature difference (ITD between the coolant temperature and air temperature of the system was higher than that associated with the highway mode; this higher ITD occurred even though the thermal load of the system in uphill mode was greater than that corresponding to the highway mode. Since the coolant inlet temperature is expected to exceed the allowable limit (80 °C in uphill mode under higher ambient temperature with air conditioning system operation, the FEM design layout should be modified to improve the heat capacity. In addition, the overall volume of the stack cooling radiator is 52.2% higher than that of the present model and the coolant inlet temperature of the improved radiator is 22.7% lower than that of the present model.

  18. High-Fidelity Aerodynamic Design with Transition Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To enhance aerodynamic design capabilities, Desktop Aeronautics proposes to significantly improve upon the integration (performed in Phase 1) of a new sweep/taper...

  19. Hypervelocity Aerodynamics and Control

    Science.gov (United States)

    1990-06-06

    Report: Hypervelocity Aerodynamics and Control 12. PERSONAL AUTHOR(S) T. C. Adamson, Jr. and R. IA. Howe 13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE...6] pulse applied. If the Mxyz system as shown is Fig. 3 r 3. , is used, then we have R21= k costo -t4 ksin yot 1 6r= ro 1 (4) -- (6k 2 - 5 -30k 2 sin

  20. Aerodynamic analysis of an isolated vehicle wheel

    Science.gov (United States)

    Leśniewicz, P.; Kulak, M.; Karczewski, M.

    2014-08-01

    Increasing fuel prices force the manufacturers to look into all aspects of car aerodynamics including wheels, tyres and rims in order to minimize their drag. By diminishing the aerodynamic drag of vehicle the fuel consumption will decrease, while driving safety and comfort will improve. In order to properly illustrate the impact of a rotating wheel aerodynamics on the car body, precise analysis of an isolated wheel should be performed beforehand. In order to represent wheel rotation in contact with the ground, presented CFD simulations included Moving Wall boundary as well as Multiple Reference Frame should be performed. Sliding mesh approach is favoured but too costly at the moment. Global and local flow quantities obtained during simulations were compared to an experiment in order to assess the validity of the numerical model. Results of investigation illustrates dependency between type of simulation and coefficients (drag and lift). MRF approach proved to be a better solution giving result closer to experiment. Investigation of the model with contact area between the wheel and the ground helps to illustrate the impact of rotating wheel aerodynamics on the car body.

  1. IEA joint action. Aerodynamics of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Maribo Pedersen, B. [ed.

    1997-12-31

    In the period 1992-1997 the IEA Annex XIV `Field Rotor Aerodynamics` was carried out. Within its framework 5 institutes from 4 different countries participated in performing detailed aerodynamic measurements on full-scale wind turbines. The Annex was successfully completed and resulted in a unique database of aerodynamic measurements. The database is stored on an ECN disc (available through ftp) and on a CD-ROM. It is expected that this base will be used extensively in the development and validation of new aerodynamic models. Nevertheless at the end of IEA Annex XIV, it was recommended to perform a new IEA Annex due to the following reasons: In Annex XIV several data exchange rounds appeared to be necessary before a satisfactory result was achieved. This is due to the huge amount of data which had to be supplied, by which a thorough inspection of all data is very difficult and very time consuming; Most experimental facilities are still operational and new, very useful, measurements are expected in the near future; The definition of angle of attack and dynamic pressure in the rotating environment is less straightforward than in the wind tunnel. The conclusion from Annex XIV was that the uncertainty which results from these different definitions is still too large and more investigation in this field is required. (EG)

  2. Modeling and Thermal Performance Evaluation of Porous Curd Layers in Sub-Cooled Boiling Region of PWRs and Effects of Sub-Cooled Nucleate Boiling on Anomalous Porous Crud Deposition on Fuel Pin Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Barclay Jones

    2005-06-27

    A significant number of current PWRs around the world are experiencing anomalous crud deposition in the sub-cooled region of the core, resulting in an axial power shift or Axial Offset Anomaly (AOA), a condition that continues to elude prediction of occurrence and thermal/neutronic performance. This creates an operational difficulty of not being able to accurately determine power safety margin. In some cases this condition has required power ''down rating'' by as much as thirty percent and the concomitant considerable loss of revenue for the utility. This study examines two aspects of the issue: thermal performance of crud layer and effect of sub-cooled nucleate boiling on the solute concentration and its influence on initiation of crud deposition/formation on fuel pin surface.

  3. Electron cooling

    Science.gov (United States)

    Meshkov, I.; Sidorin, A.

    2004-10-01

    The brief review of the most significant and interesting achievements in electron cooling method, which took place during last two years, is presented. The description of the electron cooling facilities-storage rings and traps being in operation or under development-is given. The applications of the electron cooling method are considered. The following modern fields of the method development are discussed: crystalline beam formation, expansion into middle and high energy electron cooling (the Fermilab Recycler Electron Cooler, the BNL cooler-recuperator, cooling with circulating electron beam, the GSI project), electron cooling in traps, antihydrogen generation, electron cooling of positrons (the LEPTA project).

  4. Stochastic Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz, M.

    2011-01-01

    Stochastic Cooling was invented by Simon van der Meer and was demonstrated at the CERN ISR and ICE (Initial Cooling Experiment). Operational systems were developed at Fermilab and CERN. A complete theory of cooling of unbunched beams was developed, and was applied at CERN and Fermilab. Several new and existing rings employ coasting beam cooling. Bunched beam cooling was demonstrated in ICE and has been observed in several rings designed for coasting beam cooling. High energy bunched beams have proven more difficult. Signal suppression was achieved in the Tevatron, though operational cooling was not pursued at Fermilab. Longitudinal cooling was achieved in the RHIC collider. More recently a vertical cooling system in RHIC cooled both transverse dimensions via betatron coupling.

  5. A preliminary approach to the extension of the Transuranus code to the fuel rod performance analysis of HLM-cooled nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Luzzi, L.; Botazzoli, P.; Devita, M.; Di Marcello, V.; Pastore, G. [Department of Energy, Politecnico di Milano, Enrico Fermi Center for Nuclear Studies - CeSNEF, via Ponzio 34/3, 20133 Milano (Italy)

    2010-07-01

    This paper briefly presents a preliminary modelling approach, aimed at the extension of the TRANSURANUS code to the fuel rod performance analysis of Heavy Liquid Metal (HLM) cooled nuclear reactors, with specific reference to the employment of the T91 steel as cladding material and of the liquid Lead-Bismuth Eutectic (LBE) as coolant. On the basis of literature indications, correlations for heat transfer to LBE, corrosion behaviour and thermo-mechanical properties of T91 are proposed, and some open issues are discussed in prospect of more reliable fuel rod performance analysis of HLM-cooled nuclear reactors. (authors)

  6. Performance test of current lead cooled by a cryocooler in low temperature superconducting magnet system

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yeon Suk, E-mail: ychoi@kbsi.re.kr; Kim, Myung Su

    2013-11-15

    Highlights: •The current lead with multi-contact connector in the joint was fabricated for performance test. •The electrical contact resistance in the joint was measured during magnet charging. •The resistances of the joint were 0.4–0.9 mΩ for 40–80 K. •The heat generation due to electrical contact resistance was reduced below 1 W by multiple spring louvers. -- Abstract: In a low temperature superconducting magnet system, heat leakage through current leads is one of the major factors in cryogenic load. The semi-retractable current lead is a good option because the conductive heat leakage can be eliminated after the excitation of the magnet. It is composed of a normal metal element, conducting the current from room temperature to intermediate temperature, and an HTS element, conducting the current down to liquid helium temperature. The normal metal element is disengaged from the HTS element through the multi-contact connector without disturbance to the insulating vacuum space and without requiring complete removal of the normal metal element. The intermediate block with a lockable set point is thermally connected to the first stage of cryocooler and carries current through a strip of louvered material. The electrical contact resistance of multi-contact connector in the intermediate block is measured during magnet charging process. The effects of current level as well as operating temperature on the heat generation in the joint block are also discussed.

  7. 偏航角对风力机气动性能的影响%Aerodynamic performance of wind turbine under different yaw angles

    Institute of Scientific and Technical Information of China (English)

    石亚丽; 左红梅; 杨华; 周捍珑; 沈文忠

    2015-01-01

    layer of blade surface is set as 5×10-6 m to ensure the first dimensionless size near the wall Y+<0.5 on the wall, the 2 numbers of grids are determined by the error of axial load on the airfoil in the 60%section of blades, which respectively are 6 572 451 and 2 961 385. The aerodynamic performance of models under rated condition is simulated by ANSYS CFX with the turbulence model of SST (shear stress transport), high resolution is chosen as advection scheme, and transient rotor stator as the domain interface method. The results are converted into data, processed and analyzed by MATLAB. Finally the following conclusions are drawn. The distributions of pressure coefficients along the airfoil chord in different blade sections calculated by CFD method are in good agreement with the experimental measurements, and the error on the suction surface of airfoil is mainly caused by stall separation occurring on the pressure surface of airfoil. With the increasing of yaw angle, the pressure coefficients of the suction side are increasing and the location of minimum pressure coefficient moves to airfoil trailing edge slightly. For the pressure side, the pressure coefficients increase at first and then decrease, and the location of maximum pressure coefficient moves to airfoil leading edge slightly. The axial load coefficients and tangential load coefficients of blades first decrease and then increase and then decrease again with the increase of the azimuthal angle. With the increase of the yaw angle, the axial and tangential load coefficients are both reduced. When the yaw angle is within 30°, the relative error of axial load coefficients is in the range of ±5% and the relative error of tangential load coefficients is in the range of ±15%. CFD method is higher than BEM (blade element momentum) method in forecasting accuracy of dynamic load calculation. Under yaw condition, the hysteresis characteristic of airfoil lift and drag in blade root is more remarkable than blade tip

  8. Hypersonic aerospace vehicle leading edge cooling using heat pipe, transpiration and film cooling techniques

    Science.gov (United States)

    Modlin, James Michael

    An investigation was conducted to study the feasibility of cooling hypersonic vehicle leading edge structures exposed to severe aerodynamic surface heat fluxes using a combination of liquid metal heat pipes and surface mass transfer cooling techniques. A generalized, transient, finite difference based hypersonic leading edge cooling model was developed that incorporated these effects and was demonstrated on an assumed aerospace plane-type wing leading edge section and a SCRAMJET engine inlet leading edge section. The hypersonic leading edge cooling model was developed using an existing, experimentally verified heat pipe model. Two applications of the hypersonic leading edge cooling model were examined. An assumed aerospace plane-type wing leading edge section exposed to a severe laminar, hypersonic aerodynamic surface heat flux was studied. A second application of the hypersonic leading edge cooling model was conducted on an assumed one-quarter inch nose diameter SCRAMJET engine inlet leading edge section exposed to both a transient laminar, hypersonic aerodynamic surface heat flux and a type 4 shock interference surface heat flux. The investigation led to the conclusion that cooling leading edge structures exposed to severe hypersonic flight environments using a combination of liquid metal heat pipe, surface transpiration, and film cooling methods appeared feasible.

  9. Effects of Engine Cooling Water Temperature on Performance and Emission Characteristics of a Ci Engine Operated with Biofuel Blend

    Directory of Open Access Journals (Sweden)

    Abul Hossain

    2017-03-01

    Full Text Available The temperature of the coolant is known to have significant influence on engine performance and emissions. Whereas existing literature describes the effects of coolant temperature in engines using fossil derived fuels, very few studies have investigated these effects when biofuel is used. In this study, Jatropha oil was blended separately with ethanol and butanol. It was found that the 80% jatropha oil + 20% butanol blend was the most suitable alternative, as its properties were closest to that of fossil diesel. The coolant temperature was varied between 50°C and 95°C. The combustion process enhanced for both diesel and biofuel blend, when the coolant temperature was increased. The carbon dioxide emissions for both diesel and biofuel blend were observed to increase with temperature. The carbon monoxide, oxygen and lambda values were observed to decrease with temperature. When the engine was operated using diesel, nitrogen oxides emissions correlated in an opposite manner to smoke opacity; however, nitrogen oxides emissions and smoke opacity correlated in an identical manner for biofuel blend. Brake specific fuel consumption was observed to decrease as the temperature was increased and was higher on average when the biofuel was used. The study concludes that both biofuel blend and fossil diesel produced identical correlations between coolant temperature and engine performance. The trends of nitrogen oxides and smoke emissions with cooling temperatures were not identical to fossil diesel when biofuel blend was used in the engine.

  10. Numerical Study of the Effects of Thermal Barrier Coating and Turbulence Intensity on Cooling Performances of a Nozzle Guide Vane

    Directory of Open Access Journals (Sweden)

    Prasert Prapamonthon

    2017-03-01

    Full Text Available This work presents a numerical investigation of the combined effects of thermal barrier coating (TBC with mainstream turbulence intensity (Tu on a modified vane of the real film-cooled nozzle guide vane (NGV reported by Timko (NASA CR-168289. Using a 3D conjugate heat transfer (CHT analysis, the NGVs with and without TBC are simulated at three Tus (Tu = 3.3%, 10% and 20%. The overall cooling effectiveness, TBC effectiveness and heat transfer coefficient are analyzed and discussed. The results indicate the following three interesting phenomena: (1 TBC on the pressure side (PS is more effective than that on the suction side (SS due to a fewer number of film holes on the SS; (2 for all three Tus, the variation trends of the overall cooling effectiveness are similar, and TBC plays the positive and negative roles in heat flux at the same time, and significantly increases the overall cooling effectiveness in regions cooled ineffectively by cooling air; (3 when Tu increases, the TBC effect is more significant, for example, at the highest Tu (Tu = 20% the overall cooling effectiveness can increase as much as 24% in the film cooling ineffective regions, but near the trailing edge (TE and the exits and downstream of film holes on the SS, this phenomenon is slight.

  11. Measuring the coolness of interactive products: the COOL questionnaire

    DEFF Research Database (Denmark)

    Bruun, Anders; Raptis, Dimitrios; Kjeldskov, Jesper

    2016-01-01

    characteristics. These were used to create an initial pool of question items and 2236 participants were asked to assess 16 mobile devices. By performing exploratory and confirmatory factor analyses, we identified three factors that can measure the perceived inner coolness of interactive products: desirability...... is the COOL questionnaire. We based the creation of the questionnaire on literature suggesting that perceived coolness is decomposed to outer cool (the style of a product) and inner cool (the personality characteristics assigned to it). In this paper, we focused on inner cool, and we identified 11 inner cool...

  12. Aerodynamic research on tipvane windturbines

    Science.gov (United States)

    Vanbussel, G. J. W.; Vanholten, T.; Vankuik, G. A. M.

    1982-09-01

    Tipvanes are small auxiliary wings mounted at the tips of windturbine blades in such a way that a diffuser effect is generated, resulting in a mass flow augmentation through the turbine disc. For predicting aerodynamic loads on the tipvane wind turbine, the acceleration potential is used and an expansion method is applied. In its simplest form, this method can essentially be classified as a lifting line approach, however, with a proper choice of the basis load distributions of the lifting line, the numerical integration of the pressurefield becomes one dimensional. the integration of the other variable can be performed analytically. The complete analytical expression for the pressure field consists of two series of basic pressure fields. One series is related to the basic load distributions over the turbineblade, and the other series to the basic load distribution over the tipvane.

  13. Experimental investigation of material chemical effects on emergency core cooling pump suction filter performance after loss of coolant accident

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Woon, E-mail: parkjw@dongguk.ac.k [Dongguk University, 707 Seokjang-Dong, Gyeongju, 780-714 (Korea, Republic of); Park, Byung Gi [Soonchunhyang University, Asan, Chungnam, 336-745 (Korea, Republic of); Kim, Chang Hyun [Korea Hydro and Nuclear Power Co., Ltd. 25-1, Jang-dong, Yuseong-gu, Daejeon, 305-343 (Korea, Republic of)

    2009-12-15

    Integral tests of head loss through an emergency core cooling filter screen are conducted, simulating reactor building environmental conditions for 30 days after a loss of coolant accident. A test rig with five individual loops each of whose chamber is established to test chemical product formation and measure the head loss through a sample filter. The screen area at each chamber and the amounts of reactor building materials are scaled down according to specific plant condition. A series of tests have been performed to investigate the effects of calcium-silicate, reactor building spray, existence of calcium-silicate with tri-sodium phosphate (TSP), and composition of materials. The results showed that head loss across the chemical bed with even a small amount of calcium-silicate insulation instantaneously increased as soon as TSP was added to the test solution. Also, the head loss across the filter screen is strongly affected by spray duration and the head loss increase is rapid at the early stage, because of high dissolution and precipitation of aluminum and zinc. After passivation of aluminum and zinc by corrosion, the head loss increase is much slowed down and is mainly induced by materials such as calcium, silicon, and magnesium leached from NUKON{sup TM} and concrete. Furthermore, it is newly found that the spay buffer agent, tri-sodium phosphate, to form protective coating on the aluminum surface and reduce aluminum leaching is not effective for a large amount of aluminum and a long spray.

  14. Numerical Study of High Heat Flux Performances of Flat-Tile Divertor Mock-ups with Hypervapotron Cooling Concept

    Science.gov (United States)

    Chen, Lei; Liu, Xiang; Lian, Youyun; Cai, Laizhong

    2015-09-01

    The hypervapotron (HV), as an enhanced heat transfer technique, will be used for ITER divertor components in the dome region as well as the enhanced heat flux first wall panels. W-Cu brazing technology has been developed at SWIP (Southwestern Institute of Physics), and one W/CuCrZr/316LN component of 450 mm×52 mm×166 mm with HV cooling channels will be fabricated for high heat flux (HHF) tests. Before that a relevant analysis was carried out to optimize the structure of divertor component elements. ANSYS-CFX was used in CFD analysis and ABAQUS was adopted for thermal-mechanical calculations. Commercial code FE-SAFE was adopted to compute the fatigue life of the component. The tile size, thickness of tungsten tiles and the slit width among tungsten tiles were optimized and its HHF performances under International Thermonuclear Experimental Reactor (ITER) loading conditions were simulated. One brand new tokamak HL-2M with advanced divertor configuration is under construction in SWIP, where ITER-like flat-tile divertor components are adopted. This optimized design is expected to supply valuable data for HL-2M tokamak. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2011GB110001 and 2011GB110004)

  15. Sistemas de resfriamento evaporativo e o desempenho de frangos de corte Evaporative cooling systems and the performance of broilers

    Directory of Open Access Journals (Sweden)

    Valmir Sartor

    2001-03-01

    Full Text Available As condições térmicas no interior de instalações para frangos de corte tem importância vital para o sucesso desta atividade. Desta forma, deve-se buscar o conforto térmico para as aves com o mínimo custo em materiais, equipamentos e energia. Baseado nisto foi desenvolvido um trabalho com o objetivo de avaliar o efeito de três sistemas de resfriamento evaporativo no desempenho de frangos de corte. Para isso, utilizou-se um galpão dividido em quatro partes nas quais foram instaladas os tratamentos: ventilador associado a nebulização (VNB, ventilador de alta rotação associado a nebulização (VNA, nebulização (NEB e nebulização acoplada ao ventilador (NEV. Foi registrado o consumo de ração, o ganho de peso e a mortalidade, obtendo-se assim a conversão alimentar. Os sistemas de resfriamento evaporativo (VNA e VNB proporcionaram os melhores resultados com os maiores valores de ganho de peso por ave e os menores valores de conversão alimentar e mortalidade. Resultados menos satisfatórios foram observados no NEV, com os menores valores de ganho de peso por ave e maiores valores de conversão alimentar e mortalidade.The thermal conditions inside poultry houses are very important for the success of this business. It is however necessary to have an adequate animal thermal confort and a minimum cost of material, equipment and energy. This experiment was carried to verify the effect of evaporative cooling systems on the performance of poultry. The building was divided in four equal sectors. The treatments consisted of ventilator and spraying system (VNB, high rotation ventilator and spraying system (VNA, spraying system (NEB, and spraying system connected to the ventilator (NEV. Feed intake, weight gain, mortality of poultry were recorded and the food conversion calculated. It is shown the evaporative cooling systems (VNA e VNB presented the best results, increasing weight gain with lower values of food conversion and mortalily. The

  16. Aerodynamics of wind turbines

    CERN Document Server

    Hansen, Martin O L

    2015-01-01

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design a classical pitch and torque regulator to control rotational speed and power, while the section on structural dynamics has been extended with a simplified mechanical system explaining the phenomena of forward and backward whirling modes. Readers will also benefit from a new chapter on Vertical Axis W

  17. Effect of pre-cooling on repeat-sprint performance in seasonally acclimatised males during an outdoor simulated team-sport protocol in warm conditions.

    Science.gov (United States)

    Brade, Carly J; Dawson, Brian T; Wallman, Karen E

    2013-01-01

    Whether precooling is beneficial for exercise performance in warm climates when heat acclimatised is unclear. The purpose of this study was to determine the effect of precooling on repeat-sprint performance during a simulated team-sport circuit performed outdoors in warm, dry field conditions in seasonally acclimatised males (n = 10). They performed two trials, one with precooling (PC; ice slushy and cooling jacket) and another without (CONT). Trials began with a 30-min baseline/cooling period followed by an 80 min repeat-sprint protocol, comprising 4 x 20-min quarters, with 2 x 5-min quarter breaks and a 10-min half-time recovery/cooling period. A clear and substantial (negative; PC slower) effect was recorded for first quarter circuit time. Clear and trivial effects were recorded for overall circuit time, third and fourth quarter sprint times and fourth quarter best sprint time, otherwise unclear and trivial effects were recorded for remaining performance variables. Core temperature was moderately lower (Cohen's d=0.67; 90% CL=-1.27, 0.23) in PC at the end of the precooling period and quarter 1. No differences were found for mean skin temperature, heart rate, thermal sensation, or rating of perceived exertion, however, moderate Cohen's d effect sizes suggested a greater sweat loss in PC compared with CONT. In conclusion, repeat- sprint performance was neither clearly nor substantially improved in seasonally acclimatised players by using a combination of internal and external cooling methods prior to and during exercise performed in the field in warm, dry conditions. Of practical importance, precooling appears unnecessary for repeat-sprint performance if athletes are seasonally acclimatised or artificially acclimated to heat, as it provides no additional benefit. Key PointsPre-cooling did not improve repeated sprint performance during a prolonged team-sport circuit in field conditions.If individuals are already heat acclimatised/acclimated, pre-cooling is

  18. A Study of Canard’s Influence on the Aerodynamic Performance of Box-wing Layout%鸭翼对盒式翼布局气动特性的影响研究

    Institute of Scientific and Technical Information of China (English)

    解望; 高超; 张正科; 胡旭

    2014-01-01

    盒式翼布局带有前置鸭翼对飞机纵向力矩特性产生显著的影响。针对某盒式翼布局无人机,采用数值模拟方法研究鸭翼对盒式翼布局气动性能的影响,以及鸭翼安装角、鸭翼沿机身轴线的纵向位置和鸭翼面积对巡航状态下盒式翼布局气动性能的影响。结果表明:鸭翼可以提高盒式翼布局的最大升力系数和失速迎角,可以有效地调节纵向力矩,但是会使最大升阻比略微减小;在巡航迎角3°、巡航速度50 m/s状态下,鸭翼安装角和鸭翼面积对盒式翼布局气动特性影响较大,而鸭翼纵向位置对盒式翼布局气动特性影响较小。综合考虑鸭翼的上述参数,可以显著提高盒式翼布局的气动性能。%The box‐wing layout with canard could significantly improve the whole vehicle’s longitudinal pitching moment properties .For the box‐wing layout of UAV ,the canard’s influence on the aerodynamic performance of box‐wing layout ,and the influence of the canard installation angle ,canard longitudinal position along the body axis ,and canard area on the aerodynamic performance of box‐wing layout under cruising flight are studied through numerical simulation .Results show that :canard can increase the box‐wing layout’s maximum lift coef‐ficient and the stall angle of attack ,and can effectively regulate the longitudinal pitching moment ,but will slightly reduce the maximum lift‐to‐drag ratio ;under cruising angle of attack of 3° and cruising speed of 50 m/s ,the installation angle and area of canard will have a great influence on the aerodynamic performance of box‐wing layout while the canard longitudinal position will affect less on the box‐wing layout .Above all ,it can be concluded that the canard can significantly improve aerodynamic performance of the box‐wing layout with the comprehensive consideration of these parameters of canard .

  19. Stochastic cooling in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Brennan J. M.; Blaskiewicz, M.; Mernick, K.

    2012-05-20

    The full 6-dimensional [x,x'; y,y'; z,z'] stochastic cooling system for RHIC was completed and operational for the FY12 Uranium-Uranium collider run. Cooling enhances the integrated luminosity of the Uranium collisions by a factor of 5, primarily by reducing the transverse emittances but also by cooling in the longitudinal plane to preserve the bunch length. The components have been deployed incrementally over the past several runs, beginning with longitudinal cooling, then cooling in the vertical planes but multiplexed between the Yellow and Blue rings, next cooling both rings simultaneously in vertical (the horizontal plane was cooled by betatron coupling), and now simultaneous horizontal cooling has been commissioned. The system operated between 5 and 9 GHz and with 3 x 10{sup 8} Uranium ions per bunch and produces a cooling half-time of approximately 20 minutes. The ultimate emittance is determined by the balance between cooling and emittance growth from Intra-Beam Scattering. Specific details of the apparatus and mathematical techniques for calculating its performance have been published elsewhere. Here we report on: the method of operation, results with beam, and comparison of results to simulations.

  20. 湍流强度对水平轴风力机气动性能的影响%The Influence of Turbulence Intensity on Aerodynamic Performance of Horizontal Axis Wind Turbine

    Institute of Scientific and Technical Information of China (English)

    李仁年; 任鹏; 李德顺

    2016-01-01

    In order to study the influence of turbulence intensity on aerodynamic performance of horizontal axis wind turbine,a three-dimensionally numerical simulation of wind wheel model of 33 kW horizontal ax-is wind turbine under different working conditions of wind speed of incoming flow is conducted based on CFD software by comparing and analyzing aerodynamic performance of wind turbine when the turbulence intensity(Ⅰ)is 0.1%,14% and 25%.The results show that differential pressure on the surface of horizontal axis wind turbine blade decreases on a certain degree with the increase of turbulence intensity,which causes that torque of wind wheel of wind turbine decreases and wind power utilization efficiency of wind turbine is clearly reduced.%为了研究水平轴风力机气动性能随湍流强度的影响,基于CFD软件对不同来流风速工况下的33 kW水平轴风力机风轮模型进行三维数值模拟,对比分析风力机在湍流强度Ⅰ为0.1%、14%、25%时的气动性能.结果表明:随着来流湍流强度的增加,水平轴风力机叶片表面压差会有一定程度的减小,从而导致风力机风轮转矩减小,风力机风能利用效率明显降低.

  1. Using passive cooling strategies to improve thermal performance and reduce energy consumption of residential buildings in U.A.E. buildings

    Directory of Open Access Journals (Sweden)

    Hanan M. Taleb

    2014-06-01

    Full Text Available Passive design responds to local climate and site conditions in order to maximise the comfort and health of building users while minimising energy use. The key to designing a passive building is to take best advantage of the local climate. Passive cooling refers to any technologies or design features adopted to reduce the temperature of buildings without the need for power consumption. Consequently, the aim of this study is to test the usefulness of applying selected passive cooling strategies to improve thermal performance and to reduce energy consumption of residential buildings in hot arid climate settings, namely Dubai, United Arab Emirates. One case building was selected and eight passive cooling strategies were applied. Energy simulation software – namely IES – was used to assess the performance of the building. Solar shading performance was also assessed using Sun Cast Analysis, as a part of the IES software. Energy reduction was achieved due to both the harnessing of natural ventilation and the minimising of heat gain in line with applying good shading devices alongside the use of double glazing. Additionally, green roofing proved its potential by acting as an effective roof insulation. The study revealed several significant findings including that the total annual energy consumption of a residential building in Dubai may be reduced by up to 23.6% when a building uses passive cooling strategies.

  2. The Aerodynamic Plane Table

    Science.gov (United States)

    Zahm, A F

    1924-01-01

    This report gives the description and the use of a specially designed aerodynamic plane table. For the accurate and expeditious geometrical measurement of models in an aerodynamic laboratory, and for miscellaneous truing operations, there is frequent need for a specially equipped plan table. For example, one may have to measure truly to 0.001 inch the offsets of an airfoil at many parts of its surface. Or the offsets of a strut, airship hull, or other carefully formed figure may require exact calipering. Again, a complete airplane model may have to be adjusted for correct incidence at all parts of its surfaces or verified in those parts for conformance to specifications. Such work, if but occasional, may be done on a planing or milling machine; but if frequent, justifies the provision of a special table. For this reason it was found desirable in 1918 to make the table described in this report and to equip it with such gauges and measures as the work should require.

  3. Aerodynamics of sports balls

    Science.gov (United States)

    Mehta, R. D.

    1985-01-01

    Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.

  4. The effect of local skin cooling before a sustained, submaximal isometric contraction on fatigue and isometric quadriceps femoris performance: A randomized controlled trial.

    Science.gov (United States)

    Hohenauer, Erich; Cescon, Corrado; Deliens, Tom; Clarys, Peter; Clijsen, Ron

    2017-04-01

    The central- and peripheral mechanisms by which heat strain limits physical performance are not fully elucidated. Nevertheless, pre-cooling is often used in an attempt to improve subsequent performance. This study compared the effects of pre-cooling vs. a pre-thermoneutral application on central- and peripheral fatigue during 60% of isometric maximum voluntary contraction (MVC) of the right quadriceps femoris muscle. Furthermore, the effects between a pre-cooling and a pre-thermoneutral application on isometric MVC of the right quadriceps femoris muscle and subjective ratings of perceived exertion (RPE) were investigated. In this randomized controlled trial, 18 healthy adults voluntarily participated. The participants received either a cold (experimental) application (+8°C) or a thermoneutral (control) application (+32°C) for 20min on their right thigh (one cuff). After the application, central (fractal dimension - FD) and peripheral (muscle fiber conduction velocity - CV) fatigue was estimated using sEMG parameters during 60% of isometric MVC. Surface EMG signals were detected from the vastus medialis and lateralis using bidimensional arrays. Immediately after the submaximal contraction, isometric MVC and RPE were assessed. Participants receiving the cold application were able to maintain a 60% isometric MVC significantly longer when compared to the thermoneutral group (mean time: 78 vs. 46s; p=0.04). The thermoneutral application had no significant impact on central fatigue (p>0.05) compared to the cold application (p=0.03). However, signs of peripheral fatigue were significantly higher in the cold group compared to the thermoneutral group (p=0.008). Pre-cooling had no effect on isometric MVC of the right quadriceps muscle and ratings of perceived exertion. Pre-cooling attenuated central fatigue and led to significantly longer submaximal contraction times compared to the pre-thermoneutral application. These findings support the use of pre-cooling procedures

  5. Aerodynamic Design of a Tailless Aeroplan

    Directory of Open Access Journals (Sweden)

    J. Friedl

    2001-01-01

    Full Text Available The paper presents an aerodynamic analysis of a one-seat ultralight (UL tailless aeroplane named L2k, with a very complicated layout. In the first part, an autostable airfoil with a low moment coefficient was chosen as a base for this problem. This airfoil was refined and modified to satisfy the design requirements. The computed aerodynamic characteristics of the airfoils for different Reynolds numbers (Re were compared with available experimental data. XFOIL code was used to perform the computations. In the second part, a computation of wing characteristics was carried out. All calculated cases were chosen as points on the manoeuvring and gust envelope. The vortex lattice method was used with consideration of fuselage and winglets for very complicated wing geometry. The PMW computer program developed at IAE was used to perform the computations. The computed results were subsequently used for structural and strength analysis and design.

  6. Mimicking the humpback whale: An aerodynamic perspective

    Science.gov (United States)

    Aftab, S. M. A.; Razak, N. A.; Mohd Rafie, A. S.; Ahmad, K. A.

    2016-07-01

    This comprehensive review aims to provide a critical overview of the work on tubercles in the past decade. The humpback whale is of interest to aerodynamic/hydrodynamic researchers, as it performs manoeuvres that baffle the imagination. Researchers have attributed these capabilities to the presence of lumps, known as tubercles, on the leading edge of the flipper. Tubercles generate a unique flow control mechanism, offering the humpback exceptional manoeuverability. Experimental and numerical studies have shown that the flow pattern over the tubercle wing is quite different from conventional wings. Research on the Tubercle Leading Edge (TLE) concept has helped to clarify aerodynamic issues such as flow separation, tonal noise and dynamic stall. TLE shows increased lift by delaying and restricting spanwise separation. A summary of studies on different airfoils and reported improvement in performance is outlined. The major contributions and limitations of previous work are also reported.

  7. EFFECT OF PRE-COOLING ON REPEAT-SPRINT PERFORMANCE IN SEASONALLY ACCLIMATISED MALES DURING AN OUTDOOR SIMULATED TEAM-SPORT PROTOCOL IN WARM CONDITIONS

    Directory of Open Access Journals (Sweden)

    Carly J. Brade

    2013-09-01

    Full Text Available Whether precooling is beneficial for exercise performance in warm climates when heat acclimatised is unclear. The purpose of this study was to determine the effect of precooling on repeat-sprint performance during a simulated team-sport circuit performed outdoors in warm, dry field conditions in seasonally acclimatised males (n = 10. They performed two trials, one with precooling (PC; ice slushy and cooling jacket and another without (CONT. Trials began with a 30-min baseline/cooling period followed by an 80 min repeat-sprint protocol, comprising 4 x 20-min quarters, with 2 x 5-min quarter breaks and a 10-min half-time recovery/cooling period. A clear and substantial (negative; PC slower effect was recorded for first quarter circuit time. Clear and trivial effects were recorded for overall circuit time, third and fourth quarter sprint times and fourth quarter best sprint time, otherwise unclear and trivial effects were recorded for remaining performance variables. Core temperature was moderately lower (Cohen's d=0.67; 90% CL=-1.27, 0.23 in PC at the end of the precooling period and quarter 1. No differences were found for mean skin temperature, heart rate, thermal sensation, or rating of perceived exertion, however, moderate Cohen's d effect sizes suggested a greater sweat loss in PC compared with CONT. In conclusion, repeat- sprint performance was neither clearly nor substantially improved in seasonally acclimatised players by using a combination of internal and external cooling methods prior to and during exercise performed in the field in warm, dry conditions. Of practical importance, precooling appears unnecessary for repeat-sprint performance if athletes are seasonally acclimatised or artificially acclimated to heat, as it provides no additional benefit

  8. Improving Vortex Generators to Enhance the Performance of Air-Cooled Condensers in a Geothermal Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Manohar S. Sohal

    2005-09-01

    This report summarizes work at the Idaho National Laboratory to develop strategies to enhance air-side heat transfer in geothermal air-cooled condensers such that it should not significantly increase pressure drop and parasitic fan pumping power. The work was sponsored by the U.S. Department of Energy, NEDO (New Energy and Industrial Technology Development Organization) of Japan, Yokohama National University, and the Indian Institute of Technology, Kanpur, India. A combined experimental and numerical investigation was performed to investigate heat transfer enhancement techniques that may be applicable to largescale air-cooled condensers such as those used in geothermal power applications. A transient heat transfer visualization and measurement technique was employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements were obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that included four tube rows in a staggered array. Heat transfer and pressure drop measurements were also acquired in a separate multiple-tube row apparatus in the Single Blow Test Facility. In addition, a numerical modeling technique was developed to predict local and average heat transfer for these low-Reynolds number flows, with and without winglets. Representative experimental and numerical results were obtained that reveal quantitative details of local finsurface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. Heat transfer and pressure-drop results were obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500. The winglets were of triangular (delta) shape with a 1:2 or 1:3 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface heat transfer results indicate a significant level of heat transfer enhancement (in terms of

  9. Mass production and photoelectric performances of P and Al Co-doped ZnO nanocrystals under different cooling post-processes

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Ya-Juan; Lu, Yi [Key Laboratory for Advanced Materials, East China University of Science and Technology, Shanghai 200237 (China); Liu, Jin-Ku, E-mail: jkliu@ecust.edu.cn [Key Laboratory for Advanced Materials, East China University of Science and Technology, Shanghai 200237 (China); Yang, Xiao-Hong, E-mail: yxh6110@yeah.net [Department of Chemistry, Chizhou University, Chizhou 247000 (China)

    2015-11-05

    The phosphorus and aluminum co-doped in zinc oxide (ZnO) called PAZO nano-crystals (NCs) have been mass synthesized by a combustion method, which shows a preferable photocatalytic capability and conductive ability. This article focuses on the properties of PAZO NCs experienced by three cooling-down aftertreatments, which were the normalizing, quenching and annealing process, respectively. The influences of different cooling processes on the photocatalytic and conductive performances are discussed in details. From the research, we found the quenched-PAZO NCs showed the most unappealing photocatalysis and conductivity, because excessive defects as the recombination center of electron–hole pairs were generated in the quenching process. - Graphical abstract: This research focuses on the PAZO NCs experienced by different cooling-down aftertreatments, which were the normalizing, quenching and annealing process, respectively. The quenched-PAZO NCs had the most unappealing photocatalysis and conductivity, because of generating excessive defects as the recombination center of electron–hole pairs in the quenching process. - Highlights: • We presented a method to mass synthesize co-doped P and Al in ZnO nanocrystals. • The PAZO NCs have novel photoelectric performances. • The cooling post-process influence on the photoelectric properties was studied. • The excessive defects decline the photocatalytic and conductive activities.

  10. Discrete vortex method simulations of aerodynamic admittance in bridge aerodynamics

    DEFF Research Database (Denmark)

    Rasmussen, Johannes Tophøj; Hejlesen, Mads Mølholm; Larsen, Allan;

    , and to determine aerodynamic forces and the corresponding flutter limit. A simulation of the three-dimensional bridge responseto turbulent wind is carried out by quasi steady theory by modelling the bridge girder as a line like structure [2], applying the aerodynamic load coefficients found from the current version...... of DVMFLOW in a strip wise fashion. Neglecting the aerodynamic admittance, i.e. the correlation of the instantaneous lift force to the turbulent fluctuations in the vertical velocities, leads to higher response to high frequency atmospheric turbulence than would be obtained from wind tunnel tests....

  11. Enhancement and performance evaluation for heat transfer of air cooling zone for reduction system of sponge titanium

    Science.gov (United States)

    Wang, Wenhao; Wu, Fuzhong; Jin, Huixin

    2016-05-01

    Since the magnesiothermic reduction employed in current sponge titanium is a highly exothermic reaction, the TiCl4 feed rate is carried out slowly to keep a suitable temperature in reduction reactor, which accounts for an extremely low level of productivity and energy efficiency. In order to shorten the production cycle and improve the energy efficiency, an enhancing scheme is proposed to enhance the heat transfer of air cooling zone for reduction system. The air cooling zone and enhancing scheme are firstly introduced. And then, the heat transfer characteristics of cooling zone are obtained by theoretical analysis and experimental date without enhancing scheme. Finally, the enhancement is analyzed and evaluated. The results show that the fitting results of heat transfer coefficients can be used to evaluate the heat transfer enhancement of cooling zone. Heat sources temperatures have a limited decreasing, heat transfer rate increases obviously with the enhanced cooling, and the TiCl4 feed rate can be increased significantly by 9.61 %. And the measured and calculated results are good enough to meet the design requirements.

  12. Introduction to transonic aerodynamics

    CERN Document Server

    Vos, Roelof

    2015-01-01

    Written to teach students the nature of transonic flow and its mathematical foundation, this book offers a much-needed introduction to transonic aerodynamics. The authors present a quantitative and qualitative assessment of subsonic, supersonic, and transonic flow around bodies in two and three dimensions. The book reviews the governing equations and explores their applications and limitations as employed in modeling and computational fluid dynamics.  Some concepts, such as shock and expansion theory, are examined from a numerical perspective. Others, including shock-boundary-layer interaction, are discussed from a qualitative point of view. The book includes 60 examples and more than 200 practice problems. The authors also offer analytical methods such as Method of Characteristics (MOC) that allow readers to practice with the subject matter.  The result is a wealth of insight into transonic flow phenomena and their impact on aircraft design, including compressibility effects, shock and expansion waves, sho...

  13. Wind Turbines Wake Aerodynamics

    DEFF Research Database (Denmark)

    Vermeer, L.; Sørensen, Jens Nørkær; Crespo, A.

    2003-01-01

    The aerodynamics of horizontal axis wind turbine wakes is studied. The contents is directed towards the physics of power extraction by wind turbines and reviews both the near and the far wake region. For the near wake, the survey is restricted to uniform, steady and parallel flow conditions......, thereby excluding wind shear, wind speed and rotor setting changes and yawed conditions. The emphasis is put on measurements in controlled conditions.For the far wake, the survey focusses on both single turbines and wind farm effects, and the experimental and numerical work are reviewed; the main interest...... is to study how the far wake decays downstream, in order to estimate the effect produced in downstream turbines.The article is further restricted to horizontal axis wind turbines and excludes all other types of turbines....

  14. Performance of a 10-kJ SMES model cooled by liquid hydrogen thermo-siphon flow for ASPCS study

    Science.gov (United States)

    Makida, Y.; Shintomi, T.; Hamajima, T.; Ota, N.; Katsura, M.; Ando, K.; Takao, T.; Tsuda, M.; Miyagi, D.; Tsujigami, H.; Fujikawa, S.; Hirose, J.; Iwaki, K.; Komagome, T.

    2015-12-01

    We propose a new electrical power storage and stabilization system, called an Advanced Superconducting Power Conditioning System (ASPCS), which consists of superconducting magnetic energy storage (SMES) and hydrogen energy storage, converged on a liquid hydrogen station for fuel cell vehicles. A small 10- kJ SMES system, in which a BSCCO coil cooled by liquid hydrogen was installed, was developed to create an experimental model of an ASPCS. The SMES coil is conductively cooled by liquid hydrogen flow through a thermo-siphon line under a liquid hydrogen buffer tank. After fabrication of the system, cooldown tests were carried out using liquid hydrogen. The SMES coil was successfully charged up to a nominal current of 200 A. An eddy current loss, which was mainly induced in pure aluminum plates pasted onto each pancake coils for conduction cooling, was also measured.

  15. CFD research, parallel computation and aerodynamic optimization

    Science.gov (United States)

    Ryan, James S.

    1995-01-01

    Over five years of research in Computational Fluid Dynamics and its applications are covered in this report. Using CFD as an established tool, aerodynamic optimization on parallel architectures is explored. The objective of this work is to provide better tools to vehicle designers. Submarine design requires accurate force and moment calculations in flow with thick boundary layers and large separated vortices. Low noise production is critical, so flow into the propulsor region must be predicted accurately. The High Speed Civil Transport (HSCT) has been the subject of recent work. This vehicle is to be a passenger vehicle with the capability of cutting overseas flight times by more than half. A successful design must surpass the performance of comparable planes. Fuel economy, other operational costs, environmental impact, and range must all be improved substantially. For all these reasons, improved design tools are required, and these tools must eventually integrate optimization, external aerodynamics, propulsion, structures, heat transfer and other disciplines.

  16. Aerodynamic design of the National Rotor Testbed.

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Christopher Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-01

    A new wind turbine blade has been designed for the National Rotor Testbed (NRT) project and for future experiments at the Scaled Wind Farm Technology (SWiFT) facility with a specific focus on scaled wakes. This report shows the aerodynamic design of new blades that can produce a wake that has similitude to utility scale blades despite the difference in size and location in the atmospheric boundary layer. Dimensionless quantities circulation, induction, thrust coefficient, and tip-speed-ratio were kept equal between rotor scales in region 2 of operation. The new NRT design matched the aerodynamic quantities of the most common wind turbine in the United States, the GE 1.5sle turbine with 37c model blades. The NRT blade design is presented along with its performance subject to the winds at SWiFT. The design requirements determined by the SWiFT experimental test campaign are shown to be met.

  17. A full-scale experimental set-up for assessing the energy performance of radiant wall and active chilled beam for cooling buildings

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Heiselberg, Per; Jensen, Rasmus Lund

    2015-01-01

    in decreasing the cooling need of the radiant wall compared to the active chilled beam. It has also been observed that the type and repartition of heat load have an influence on the cooling demand. Regarding the comfort level, both terminals met the general requirements, except at high solar heat gains......Full-scale experiments under both steady-state and dynamic conditions have been performed to compare the energy performance of a radiant wall and an active chilled beam. From these experiments, it has been observed that the radiant wall is a more secure and efficient way of removing heat from...... the test room than the active chilled beam. The energy saving, which can be estimated to around 10%, is due to increased ventilation losses. The asymmetry between air and radiant temperature, the air temperature gradient and the possible short-circuit between inlet and outlet play an equally important role...

  18. Effect of thermal barrier coatings on the performance of steam and water-cooled gas turbine/steam turbine combined cycle system

    Science.gov (United States)

    Nainiger, J. J.

    1978-01-01

    An analytical study was made of the performance of air, steam, and water-cooled gas-turbine/steam turbine combined-cycle systems with and without thermal-barrier coatings. For steam cooling, thermal barrier coatings permit an increase in the turbine inlet temperature from 1205 C (2200 F), resulting in an efficiency improvement of 1.9 percentage points. The maximum specific power improvement with thermal barriers is 32.4 percent, when the turbine inlet temperature is increased from 1425 C (2600 F) to 1675 C (3050 F) and the airfoil temperature is kept the same. For water cooling, the maximum efficiency improvement is 2.2 percentage points at a turbine inlet temperature of 1683 C (3062 F) and the maximum specific power improvement is 36.6 percent by increasing the turbine inlet temperature from 1425 C (2600 F) to 1730 C (3150 F) and keeping the airfoil temperatures the same. These improvements are greater than that obtained with combined cycles using air cooling at a turbine inlet temperature of 1205 C (2200 F). The large temperature differences across the thermal barriers at these high temperatures, however, indicate that thermal stresses may present obstacles to the use of coatings at high turbine inlet temperatures.

  19. Heating and Cooling Performance Optimization of Power,Heating and Cooling Poly-Generation Photovoltaic Radiant Panel%电热冷联产光伏辐射板集热集冷性能优化

    Institute of Scientific and Technical Information of China (English)

    孙勇; 王一平; 魏世超; 黄群武; 朱丽; 崔勇

    2016-01-01

    建立了电热冷联产光伏辐射板(PV/R)组件三维计算流体力学模型,采用Fluent软件进行了夏季晴天工况下管间距和操作流量对组件集热集冷性能影响的模拟分析与优化,并探讨了 PV/R 组件的经济性和运行模式.集热模式下,PV/R 组件电池平均工作温度能控制到50,℃以下,增加流体流量、减小铜管间距有利于降低电池工作温度,但减小管间距不利于集热温度和集热效率的提高.集冷模式下,提高流体与环境之间温差能有效提升辐射制冷功率,流体与环境温差为5~10,℃时,辐射制冷功率达到40~90,W/m2.权衡集热和集冷性能,PV/R 组件优化管间距和适宜流量范围分别为130,mm 和180~240,L/h,对应的集热温度、集热效率和辐射制冷功率分别为38~45,℃、48%,~52%,和50~60,W/m2.%3D computational fluid dynamics models of power,heating and cooling poly-generation photovoltaic radiant panel(PV/R)module were established,and influences of tube spacing and flow rate on heating and cooling performance of PV/R module in summer conditions were analyzed using Fluent.Economical and operation mode were discussed simultaneously.For heat-collecting mode,average working temperature of PV/R module can be controlled below 50,℃ and the working temperature of solar cell decreases with raising flow rate and decreasing tube spacing, but decreasing tube spacing is not beneficial to increasing heat-collecting temperature and efficiency.For cooling mode,increasing inlet and ambient temperature difference can effectively improve radiant cooling rate,and its value can reach 40—90 W/m2 when temperature difference is 5—10,℃.Taking heating and cooling performance into con-sideration,recommended tube spacing and flow rate are 130 mm and 180—240,L/h respectively,the corresponding heat-collecting temperature and efficiency and radiant cooling rate being 38—45,℃,48%,—52%, and 50—60,W/m2 respectively.

  20. Naval Aerodynamics Test Facility (NATF)

    Data.gov (United States)

    Federal Laboratory Consortium — The NATF specializes in Aerodynamics testing of scaled and fullsized Naval models, research into flow physics found on US Navy planes and ships, aerosol testing and...

  1. Computational aerodynamics and artificial intelligence

    Science.gov (United States)

    Mehta, U. B.; Kutler, P.

    1984-01-01

    The general principles of artificial intelligence are reviewed and speculations are made concerning how knowledge based systems can accelerate the process of acquiring new knowledge in aerodynamics, how computational fluid dynamics may use expert systems, and how expert systems may speed the design and development process. In addition, the anatomy of an idealized expert system called AERODYNAMICIST is discussed. Resource requirements for using artificial intelligence in computational fluid dynamics and aerodynamics are examined. Three main conclusions are presented. First, there are two related aspects of computational aerodynamics: reasoning and calculating. Second, a substantial portion of reasoning can be achieved with artificial intelligence. It offers the opportunity of using computers as reasoning machines to set the stage for efficient calculating. Third, expert systems are likely to be new assets of institutions involved in aeronautics for various tasks of computational aerodynamics.

  2. 导叶对涡轮型垂直轴风力机气动性能的影响%Effects of guiding vanes on aerodynamic performance of vortex vertical axis wind turbine

    Institute of Scientific and Technical Information of China (English)

    原红红; 赵振宙; 郑源; 黄娟

    2013-01-01

    To overcome the problem of low efficiency of the traditional vertical axis wind turbine, the structural advantages of the wind turbine with guiding vanes are introduced and the effects of guiding vanes on the vortex vertical axis wind turbine are analyzed in detail. Based on computational fluid dynamics theory, the slippage mesh technique and the k-ε model were used to compare the aerodynamic performance of the vortex vertical axis wind turbine with and without guiding vanes at a design velocity of 12 m/s. Studies have shown that the guiding vanes can effectively prevent the direct impact of the coming flow from acting on the suction section of the blade in the upwind area so as to decrease the drag torque, while the guiding vanes also negatively affect the performance of blades in the downwind area, but the positive effect of the former is more significant, so the performance of a wind turbine with guiding vanes greatly improves. The vortex vertical axis wind turbine with arc-type guiding vanes has a wider operating range, higher optimum tip speed ratio, and higher aerodynamic efficiency. The maximum wind power coefficient can reach 0.24 .%针对传统垂直轴风力机效率低的缺陷,阐述带导叶垂直轴风力机的结构优势,并分析导叶对涡轮型垂直轴风力机的作用。应用计算流体力学理论,在设计风速12 m/s下,采用滑移网格技术及k-着模型对有、无导叶两种涡轮型垂直轴风力机的气动性能进行比较。研究表明,导叶可以有效降低由于来流对逆风区叶片吸力面的直接冲击而造成的阻力扭矩,也会负面影响顺风区叶片的性能,但其负作用效果远不及在逆风区挡流降阻的正作用效果,故加导叶后风轮的性能会有很大提高。带弧线形导叶涡轮型垂直轴风力机最大风能利用系数可达0.24,具有工作范围广、最佳尖速比大的特点。

  3. Effect of cooled EGR on performance and exhaust gas emissions in EFI spark ignition engine fueled by gasoline and wet methanol blends

    Science.gov (United States)

    Rohadi, Heru; Syaiful, Bae, Myung-Whan

    2016-06-01

    Fuel needs, especially the transport sector is still dominated by fossil fuels which are non-renewable. However, oil reserves are very limited. Furthermore, the hazardous components produced by internal combustion engine forces many researchers to consider with alternative fuel which is environmental friendly and renewable sources. Therefore, this study intends to investigate the impact of cooled EGR on the performance and exhaust gas emissions in the gasoline engine fueled by gasoline and wet methanol blends. The percentage of wet methanol blended with gasoline is in the range of 5 to 15% in a volume base. The experiment was performed at the variation of engine speeds from 2500 to 4000 rpm with 500 intervals. The re-circulated exhaust gasses into combustion chamber was 5%. The experiment was performed at the constant engine speed. The results show that the use of cooled EGR with wet methanol of 10% increases the brake torque up to 21.3%. The brake thermal efficiency increases approximately 39.6% using cooled EGR in the case of the engine fueled by 15% wet methanol. Brake specific fuel consumption for the engine using EGR fueled by 10% wet methanol decreases up to 23% at the engine speed of 2500 rpm. The reduction of CO, O2 and HC emissions was found, while CO2 increases.

  4. Improved blade element momentum theory for wind turbine aerodynamic computations

    DEFF Research Database (Denmark)

    Sun, Zhenye; Chen, Jin; Shen, Wen Zhong;

    2016-01-01

    Blade element momentum (BEM) theory is widely used in aerodynamic performance predictions and design applications for wind turbines. However, the classic BEM method is not quite accurate which often tends to under-predict the aerodynamic forces near root and over-predict its performance near tip....... The reliability of the aerodynamic calculations and design optimizations is greatly reduced due to this problem. To improve the momentum theory, in this paper the influence of pressure drop due to wake rotation and the effect of radial velocity at the rotor disc in the momentum theory are considered. Thus...... the axial induction factor in far downstream is not simply twice of the induction factor at disc. To calculate the performance of wind turbine rotors, the improved momentum theory is considered together with both Glauert's tip correction and Shen's tip correction. Numerical tests have been performed...

  5. Introduction to wind turbine aerodynamics

    CERN Document Server

    Schaffarczyk, Alois Peter

    2014-01-01

    Wind-Turbine Aerodynamics is a self-contained textbook which shows how to come from the basics of fluid mechanics to modern wind turbine blade design. It presents a fundamentals of fluid dynamics and inflow conditions, and gives a extensive introduction into theories describing the aerodynamics of wind turbines. After introducing experiments the book applies the knowledge to explore the impact on blade design.The book is an introduction for professionals and students of very varying levels.

  6. Aerodynamics of a rigid curved kite wing

    CERN Document Server

    Maneia, Gianmauro; Tordella, Daniela; Iovieno, Michele

    2013-01-01

    A preliminary numerical study on the aerodynamics of a kite wing for high altitude wind power generators is proposed. Tethered kites are a key element of an innovative wind energy technology, which aims to capture energy from the wind at higher altitudes than conventional wind towers. We present the results obtained from three-dimensional finite volume numerical simulations of the steady air flow past a three-dimensional curved rectangular kite wing (aspect ratio equal to 3.2, Reynolds number equal to 3x10^6). Two angles of incidence -- a standard incidence for the flight of a tethered airfoil (6{\\deg}) and an incidence close to the stall (18{\\deg}) -- were considered. The simulations were performed by solving the Reynolds Averaged Navier-Stokes flow model using the industrial STAR-CCM+ code. The overall aerodynamic characteristics of the kite wing were determined and compared to the aerodynamic characteristics of the flat rectangular non twisted wing with an identical aspect ratio and section (Clark Y profil...

  7. The Effect of Vegetation Coverage and Greenhouse Area on the Performance of an Earth-to-Air Heat Exchanger in Cooling Mode of Greenhouse

    Directory of Open Access Journals (Sweden)

    M Mohammadi Mogharreb

    2013-02-01

    Full Text Available The underground temperature at a depth of about three to four meters is almost constant during the year. As a result in summer the underground is cooler than the ambient temperature. This potential is considered for greenhouse cooling by using an Earth-to-Air Heat Exchanger (EAHE. In this research the effects of two parameters were investigated: a the area of greenhouse in three levels of 9, 18, 27 m2 and b the percent of vegetation coverage inside the greenhouse in three levels of 0%, 50%, 100% on the performance of EAHE. The experimental design was factorial experiment in a randomized complete block design. The parameters of greenhouse’s inside temperature, thermal energy exchange and coefficient of performance (COP were considered in cooling mode. As one of the remarkable results it was observed that the closed loop utilization of the system was infeasible in cooling mode. This was mainly due to the occurrence of vapor distillation inside the underground pipes and hence the blockages of the air flow. Also the effect of area and the percent of vegetation coverage were significant on the performance of EAHE. The highest average temperature difference between the temperature of testimonial greenhouse and the temperature of greenhouse was observed in treatment of 100% vegetation coverage and 9 m2 floor area which was measured as 9.6°C. The least average temperature difference in the treatment without vegetation coverage and 27 m2 floor area was measured as 5.2 °C. Considering thermal energy exchange in cooling greenhouse with open loop, the best treatment determined for EAHE in this research was the one with 9 m2 floor area and 100% of vegetation coverage.

  8. Spectroscopic properties and laser performance of resonantly-pumped cryo-cooled Er³⁺:GdVO₄.

    Science.gov (United States)

    Ter-Gabrielyan, N; Fromzel, V; Ryba-Romanowski, W; Lukasiewicz, T; Dubinskii, M

    2012-03-12

    We report a highly efficient cryo-cooled eye-safe laser operation of a resonantly-pumped (in-band) Er³⁺:GdVO₄ single crystal. The maximum continuous wave (CW) power of 10.3 W with 84% slope efficiency was achieved at 1598.7 with pumping at 1538.6 nm by a spectrally-narrowed Er-fiber laser. Under the 1529 nm resonant pumping by a commercially available diode bar stack operating in a quasi-CW (QCW) mode, the laser delivered 37 W of output power with 68% slope efficiency. This is believed to be the first reported cryo-cooled Er³⁺:GdVO₄ laser, resonantly-pumped into the ⁴I₁₅/₂ →⁴I₁₃/₂ transition.

  9. Aerodynamic Optimization of a Winglet Design

    Directory of Open Access Journals (Sweden)

    Yahiaoui T.

    2013-04-01

    Full Text Available In the present study, an experimental study is presented for a flow around an isolated wing equipped by a winglet and profiled with Naca 0012. Several cases of winglets were tested according to the angle ß: 0°, 55°, 65°and 75°. For all these cases at a velocity of 20, 30 and 40 meters per second, wind tunnel tests are performed and compared for different angles of incidence. It is observed that the aerodynamic performance of the winglet with β= 55° differ favorably for positive angle of incidence compared for other cases.

  10. Aerodynamics of badminton shuttlecocks

    Science.gov (United States)

    Verma, Aekaansh; Desai, Ajinkya; Mittal, Sanjay

    2013-08-01

    A computational study is carried out to understand the aerodynamics of shuttlecocks used in the sport of badminton. The speed of the shuttlecock considered is in the range of 25-50 m/s. The relative contribution of various parts of the shuttlecock to the overall drag is studied. It is found that the feathers, and the net in the case of a synthetic shuttlecock, contribute the maximum. The gaps, in the lower section of the skirt, play a major role in entraining the surrounding fluid and causing a difference between the pressure inside and outside the skirt. This pressure difference leads to drag. This is confirmed via computations for a shuttlecock with no gaps. The synthetic shuttle experiences more drag than the feather model. Unlike the synthetic model, the feather shuttlecock is associated with a swirling flow towards the end of the skirt. The effect of the twist angle of the feathers on the drag as well as the flow has also been studied.

  11. Introduction. Computational aerodynamics.

    Science.gov (United States)

    Tucker, Paul G

    2007-10-15

    The wide range of uses of computational fluid dynamics (CFD) for aircraft design is discussed along with its role in dealing with the environmental impact of flight. Enabling technologies, such as grid generation and turbulence models, are also considered along with flow/turbulence control. The large eddy simulation, Reynolds-averaged Navier-Stokes and hybrid turbulence modelling approaches are contrasted. The CFD prediction of numerous jet configurations occurring in aerospace are discussed along with aeroelasticity for aeroengine and external aerodynamics, design optimization, unsteady flow modelling and aeroengine internal and external flows. It is concluded that there is a lack of detailed measurements (for both canonical and complex geometry flows) to provide validation and even, in some cases, basic understanding of flow physics. Not surprisingly, turbulence modelling is still the weak link along with, as ever, a pressing need for improved (in terms of robustness, speed and accuracy) solver technology, grid generation and geometry handling. Hence, CFD, as a truly predictive and creative design tool, seems a long way off. Meanwhile, extreme practitioner expertise is still required and the triad of computation, measurement and analytic solution must be judiciously used.

  12. Passive low energy cooling of buildings

    CERN Document Server

    Givoni, Baruch

    1994-01-01

    A practical sourcebook for building designers, providing comprehensive discussion of the impact of basic architectural choices on cooling efficiency, including the layout and orientation of the structure, window size and shading, exterior color, and even the use of plantings around the site. All major varieties of passive cooling systems are presented, with extensive analysis of performance in different types of buildings and in different climates: ventilation; radiant cooling; evaporative cooling; soil cooling; and cooling of outdoor spaces.

  13. Performance of a methane-fuel cooled gutter type flame holder for a ramjet engine combustor. Ramu jet engine nenshokiyo metan nenryomaku reikyaku gatta hoenki no tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Tamaru, T.; Shimodaira, K. (National Aerospace Lab., Chofu, Tokyo (Japan))

    1994-03-10

    A flame holder in which the items requested for a combustor were satisfied as much as possible besides reducing the NOx exhaust, was designed and manufactured. Namely a flame holder which satisfied the total pressure loss ratio below 8% (total pressure loss coefficient 2.86) under a drafting condition of the flight mach number M[sub F] 3, certainly performed a flame holding and stable combustion, and had a flame holder temperature level to be able to secure a durability under a condition of M[sub F]=5, was aimed at. This combustor model was named CG 01, and attaching importance to a pressure loss, flame holder temperature, stable combustibility and so forth, and the tests mainly about a fuel cooling performance of the flame holder have been carried out. Generally speaking, a film cooling convective heat transfer heat flux is seen a dependency on an air velocity. In the tests this time, in a high air velocity condition of T(01)=600 K, there is a possibility that an outer diameter side fuel cooling film was broken away. When a supply air temperature was 900 K or 1200 K, and an equivalent ratio was 0.4 - 0.5, a convection heat transfer heat flux was in an order of 20 - 40 kW/m[sup 2]. 7 refs., 12 figs., 1 tab.

  14. Skylon Aerodynamics and SABRE Plumes

    Science.gov (United States)

    Mehta, Unmeel; Afosmis, Michael; Bowles, Jeffrey; Pandya, Shishir

    2015-01-01

    An independent partial assessment is provided of the technical viability of the Skylon aerospace plane concept, developed by Reaction Engines Limited (REL). The objectives are to verify REL's engineering estimates of airframe aerodynamics during powered flight and to assess the impact of Synergetic Air-Breathing Rocket Engine (SABRE) plumes on the aft fuselage. Pressure lift and drag coefficients derived from simulations conducted with Euler equations for unpowered flight compare very well with those REL computed with engineering methods. The REL coefficients for powered flight are increasingly less acceptable as the freestream Mach number is increased beyond 8.5, because the engineering estimates did not account for the increasing favorable (in terms of drag and lift coefficients) effect of underexpanded rocket engine plumes on the aft fuselage. At Mach numbers greater than 8.5, the thermal environment around the aft fuselage is a known unknown-a potential design and/or performance risk issue. The adverse effects of shock waves on the aft fuselage and plumeinduced flow separation are other potential risks. The development of an operational reusable launcher from the Skylon concept necessitates the judicious use of a combination of engineering methods, advanced methods based on required physics or analytical fidelity, test data, and independent assessments.

  15. A generalized solution of elasto-aerodynamic lubrication for aerodynamic compliant foil bearings

    Institute of Scientific and Technical Information of China (English)

    YU; Lie; QI; Shemiao; GENG; Haipeng

    2005-01-01

    Although aerodynamic compliant foil bearings are successfully applied in a number of turbo-machineries, theoretical researches on the modeling, performance prediction of compliant foil bearings and the dynamic analysis of the related rotor system seem still far behind the experimental investigation because of structural complexity of the foil bearings. A generalized solution of the elasto-aerodynamic lubrication is presented in this paper by introducing both static and dynamic deformations of foils and solving gas-lubricated Reynolds equations with deformation equations simultaneously. The solution can be used for the calculation of dynamic stiffness and damping, as well as the prediction of static performances of foil bearings. Systematical theories and methods are also presented for the purpose of the prediction of dynamic behavior of a rotor system equipped with foil bearings.

  16. 变冲角下吸力面小翼对压气机叶栅气动性能的影响%Effects of Suction-Side Winglet on Aerodynamic Performance of Compressor Cascade at Different Incidences

    Institute of Scientific and Technical Information of China (English)

    韩少冰; 钟兢军

    2012-01-01

    In order to further uncover the effects and action mechanics of the suction-side winglet on the tip leakage flow of the compressor cascade,the numerical simulation has been carried out to investigate the effects of suction-side winglet on controlling tip clearance flow in an axial compressor cascade.Emphasis is put on the analysis of effectiveness of suction-side winglet when the approaching flow is at different incidences(-5°,0°,+3°).The simulation results show that,at negative incidence,the suction-side winglet can reduce the cascade aerodynamic loss significantly and the boundary separation on pressure surface can be effectively controlled by using suction-side winglet.With the increase of incidence,the region under the effect of pressure difference extends towards the blade leading edge,and the interaction between leakage vortices and passage vortex is intensified.The improvement of suction-side winglet on the aerodynamic performance decreases gradually.%为了进一步揭示吸力面小翼对压气机叶栅间隙流动的影响机理,采用数值模拟方法对压气机叶栅加装吸力面小翼控制间隙流动进行研究,着重考察了吸力面小翼在不同来流冲角下(-5°、0°、+3°)对叶栅气动性能的影响。结果显示,负冲角时,吸力面小翼有效降低了叶尖泄漏损失及遏制了压力面分离。随着冲角增加,叶顶最大压差作用区向叶栅上游移动,泄漏涡与通道涡的相互作用增强,吸力面小翼对叶栅气动性能的改善逐渐降低。

  17. Cooling with Superfluid Helium

    CERN Document Server

    Lebrun, P

    2014-01-01

    The technical properties of helium II (‘superfluid’ helium) are presented in view of its applications to the cooling of superconducting devices, particularly in particle accelerators. Cooling schemes are discussed in terms of heat transfer performance and limitations. Large-capacity refrigeration techniques below 2 K are reviewed, with regard to thermodynamic cycles as well as process machinery. Examples drawn from existing or planned projects illustrate the presentation. Keywords: superfluid helium, cryogenics

  18. Aerodynamic Design of a Locomotive Fairing

    Science.gov (United States)

    Stucki, Chad; Maynes, Daniel

    2016-11-01

    Rising fuel cost has motivated increased fuel efficiency of freight trains. At cruising speed, the largest contributing factor to the fuel consumption is the aerodynamic drag. As a result of air stagnation at the front of the train and substantial flow separation behind, the leading locomotive and trailing railcar experience greater drag than intermediate cars. This work introduces the design of streamlined nose fairings to be attached to freight locomotives as a means of reducing the leading locomotive drag. The aerodynamic performance of each fairing design is modeled using a commercial CFD software package. The K-epsilon turbulence model is used, and fluid properties are equivalent to atmospheric air at standard conditions. A selection of isolated screening studies are performed, and a multidimensional regression is used to predict optimal-performing fairing designs. Between screening studies, careful examination of the flow field is performed to inspire subsequent fairing designs. Results are presented for 250 different nose fairings. The best performing fairing geometry predicts a nominal drag reduction of 17% on the lead locomotive in a train set. This drag reduction is expected to result in nearly 1% fuel savings for the entire train.

  19. Discrete vortex method simulations of aerodynamic admittance in bridge aerodynamics

    DEFF Research Database (Denmark)

    Rasmussen, Johannes Tophøj; Hejlesen, Mads Mølholm; Larsen, Allan

    , and to determine aerodynamic forces and the corresponding flutter limit. A simulation of the three-dimensional bridge responseto turbulent wind is carried out by quasi steady theory by modelling the bridge girder as a line like structure [2], applying the aerodynamic load coefficients found from the current version...... of DVMFLOW in a strip wise fashion. Neglecting the aerodynamic admittance, i.e. the correlation of the instantaneous lift force to the turbulent fluctuations in the vertical velocities, leads to higher response to high frequency atmospheric turbulence than would be obtained from wind tunnel tests....... In the present work we have extended the laminar oncoming flow in DVMFLOW to a turbulent one, modelled by seeding the upstream flow with vortex particles synthesized from prescribed atmospheric turbulence velocity spectra [3] . The discrete spectrum is sampled from the continuous spectrum subject to a lower cutoff...

  20. 复杂几何细节对增升装置气动性能影响研究%Study on Influence of Complex Geometry Details on the Aerodynamic Performance of High-lift System

    Institute of Scientific and Technical Information of China (English)

    邱亚松; 白俊强; 李亚林; 周涛

    2012-01-01

    By numerical simulation, the influence of the main-wing root geometry details, wing-mounted engine nacelle, slat tracks and flap track fairings on the aerodynamic performance of a high-lift system is investigated. The results show that a separated low-power vortex is generated by the wing-root fairing which is left at the main-wing root when the slat is cut, and the aerodynamic performance of the lift system is damaged seriously by this vortex. Cutting most of the wing-root fairing as part of the slat can eliminate the condition needed to generate the separated low-power vortex. Remarkable decrease of the stall angle and maxim lift coefficient is caused by a large size wing-mounted engine nacelle. This is mainly because of the flow mechanism that a large space filled with low-speed fluid above the upper surface of the main wing is generated by the separated fluid which comes from the nacelle upper surface, pylon and the gaps between the pylon and slat. Strong vortices generated by the nacelle strake with proper shape and setting at proper positions can eliminate most of the low-speed fluid and recover part of the aerodynamic performance loss. Low-momentum wake flow generated by the slat tracks mixed with the boundary layer of the main wing causes the loss of the lift. Large fluid separation may be caused by the slat track at high angles of attack, which will result in a remarkable loss of the aerodynamic performance. The flap slot section area may be diminished as a result of the blockage effect of the large size geometry the of flap track fairings, which may cause the high speed flow of the flap slot to move faster, thus blowing away the separation flow on the flap surface.%采用数值模拟的方法研究了主翼翼根几何形状、翼吊发动机短舱、缝翼滑轨及襟翼滑轨舱等几何细节对增升装置气动性能的影响.研究结果表明:切割前缘缝翼时,将大部分翼根整流包留在主翼上会在大迎角下产生低能量的分离

  1. Evaluation of the aerodynamic performances of a new vertical axis wind turbine type derived from the Savonius rotor; Prevision des performances aerodynamiques d'un nouveau type d'eolienne a axe vertical derivee du rotor Savonius

    Energy Technology Data Exchange (ETDEWEB)

    Jean-Luc Menet [Ecole Nationale Superieure d' Ingenieurs en Informatique Automatique Mecanique energetique electronique de Valenciennes, Universite de Valenciennes, Le Mont Houy F-59313 Valenciennes Cedex 9, (France); Andrew Leiper [Department of Engineering, University of Aberdeen, Aberdeen, Scotland (United Kingdom)

    2005-07-01

    The Savonius rotor is a slow running vertical axis wind turbine, the advantages of which are numerous; however, it has a poor aerodynamic efficiency. We present a study aiming to raise this efficiency by adjusting several geometrical parameters, in particular the overlap of the paddles and their respective position. The results are coming from a bidimensional numerical simulation, using the CFD code Fluent v6.0. First the numerical model is validated on the conventional Savonius rotor. Then the geometry of an optimised Savonius rotor is proposed, the overlap ratio of which is 0.242. Last a different positioning of the paddles leads to an optimal paddle angle of about 55 degrees, corresponding to the maximum of the mean starting torque coefficient. (authors)

  2. Effect of species of cool-season annual grass interseeded into Bermudagrass sod on the performance of growing calves.

    Science.gov (United States)

    Beck, P A; Stewart, C B; Phillips, J M; Watkins, K B; Gunter, S A

    2007-02-01

    Two experiments were conducted to evaluate the effect of species of cool-season annual grass on the growth of stocker cattle over 3 yr. In Exp. 1, the small grains (SG) oat (O), rye (R), and wheat (W), or combinations of SG and annual ryegrass (RG), were interseeded into Bermudagrass sod in a completely randomized design with a 3 x 2 factorial arrangement of treatments. In Exp. 2, RG was planted alone or with O, R, triticale (T), or W in a completely randomized design. Pastures were planted in late October of each year, and seeding rates were 134.4 and 22.4 kg/ha for SG and RG, respectively. In Exp. 1, grazing was initiated on December 18. In Exp. 2, grazing was initiated on December 23 for SG pastures and January 21 or February 16 for RG pastures in yr 1 and on December 8 for all pastures in yr 2. Grazing was managed using the put-and-take method, in which additional calves were added as needed to maintain equal grazing pressure among pastures. In Exp. 1, no interactions (P > or = 0.28) were detected, so the main effects of SG species and RG addition are discussed. From December 18 to March 12, there were no differences in ADG (P > or = 0.17), whereas during the spring (from March 12 to May 7), addition of RG increased (P = 0.05) ADG. Using RG increased (P or = 0.44) in ADG, BW gain/hectare, or grazing-days/hectare. In conclusion, the choice of cool-season annual to establish is highly weather-dependent, but R and W are generally superior to other small grains, and RG is a necessary complement to SG when interseeding cool-season annuals into Bermudagrass sod.

  3. Microtextured Surfaces for Turbine Blade Impingement Cooling

    Science.gov (United States)

    Fryer, Jack

    2014-01-01

    Gas turbine engine technology is constantly challenged to operate at higher combustor outlet temperatures. In a modern gas turbine engine, these temperatures can exceed the blade and disk material limits by 600 F or more, necessitating both internal and film cooling schemes in addition to the use of thermal barrier coatings. Internal convective cooling is inadequate in many blade locations, and both internal and film cooling approaches can lead to significant performance penalties in the engine. Micro Cooling Concepts, Inc., has developed a turbine blade cooling concept that provides enhanced internal impingement cooling effectiveness via the use of microstructured impingement surfaces. These surfaces significantly increase the cooling capability of the impinging flow, as compared to a conventional untextured surface. This approach can be combined with microchannel cooling and external film cooling to tailor the cooling capability per the external heating profile. The cooling system then can be optimized to minimize impact on engine performance.

  4. Basic regulations and standards for and performance of measurements in wet cooling towers; Norm-Grundlagen und praktische Durchfuehrung von Leistungsmessungen an Nasskuehltuermen

    Energy Technology Data Exchange (ETDEWEB)

    Tesche, W. [Balcke-Duerr GmbH, Ratingen (Germany). Geschaeftsbereich Nasskuehlung

    1998-09-01

    Performance measurement in wet cooling towers is a process well covered and specified by national standards, which meanwhile have been harmonized. The European standard recently eleaborated by the cooling tower manufacturing firms that are members of the VDMA association reflects the state of the art and presents a regulatory framework for applications that has been well tuned to conditions met in practice. Evaluation of measurements relies on a comparative analysis of measured data with the cooling characteristics supplied by the manufacturer, either in the form of a diagram, a computer program, or as tabulated information. (orig./CB) [Deutsch] Leistungsmessungen am Nasskuehlturm sind in laenderspezifischen Normen genau spezifiziert. Die Normen haben sich mittlerweile angeglichen. Die von dem im VDMA zusammengeschlossenen Kuehlturmfirmen erarbeitete Euronorm zu diesem Thema spiegelt den aktuellen Stand in einer praxisnahen Durchfuehrungsverordnung wieder. Die Bewertung der Messung erfolgt im Vergleich mit der vor Messbeginn bekannten Kuehlcharakteristik, die entweder als Diagramm, Rechenprogramm oder zumindest als Tabelle vom Lieferanten erstellt wurde. (orig./GL)

  5. Application of CAD/CAE class systems to aerodynamic analysis of electric race cars

    Science.gov (United States)

    Grabowski, L.; Baier, A.; Buchacz, A.; Majzner, M.; Sobek, M.

    2015-11-01

    Aerodynamics is one of the most important factors which influence on every aspect of a design of a car and car driving parameters. The biggest influence aerodynamics has on design of a shape of a race car body, especially when the main objective of the race is the longest distance driven in period of time, which can not be achieved without low energy consumption and low drag of a car. Designing shape of the vehicle body that must generate the lowest possible drag force, without compromising the other parameters of the drive. In the article entitled „Application of CAD/CAE class systems to aerodynamic analysis of electric race cars” are being presented problems solved by computer analysis of cars aerodynamics and free form modelling. Analysis have been subjected to existing race car of a Silesian Greenpower Race Team. On a basis of results of analysis of existence of Kammback aerodynamic effect innovative car body were modeled. Afterwards aerodynamic analysis were performed to verify existence of aerodynamic effect for innovative shape and to recognize aerodynamics parameters of the shape. Analysis results in the values of coefficients and aerodynamic drag forces. The resulting drag forces Fx, drag coefficients Cx(Cd) and aerodynamic factors Cx*A allowed to compare all of the shapes to each other. Pressure distribution, air velocities and streams courses were useful in determining aerodynamic features of analyzed shape. For aerodynamic tests was used Ansys Fluent CFD software. In a paper the ways of surface modeling with usage of Realize Shape module and classic surface modeling were presented. For shapes modeling Siemens NX 9.0 software was used. Obtained results were used to estimation of existing shapes and to make appropriate conclusions.

  6. Performance in cooling mode of a heat pump using panels with PV cells as the condenser; Taiyo denchitsuki panel wo gyoshukuki to shita heat pump no reibo unten

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, T.; Ito, S.; Miura, N. [Kanagawa Institute of Technology, Kanagawa (Japan); Fujita, M. [Chubu Electric Power Co. Inc., Nagoya (Japan)

    1996-10-27

    Comparison was made between heat pumps in cooling operation, one having two panels provided with solar cells, the second having an air-cooled heat exchanger alone, and the third having a series connection of a panel unit and air-cooled heat exchanger, all serving as condenser. The results are shown below. In the case of two-panel-unit condenser, there is a difference ({Delta}t) of 15{degree}C between the daytime free air temperature and condensing temperature but, with decreased insolation, free air temperature, and wind speed in the evening, the {Delta}t lowered to approximately 8{degree}C while the COP (coefficient of performance) increased from 2.4 to 3.3. On a cloudy day in summer, the two-panel-unit condenser had a {Delta}t of 13.9{degree}C and a COP of 3.1. In the case of the series-connection condenser, the {Delta}t was approximately 8{degree}C and the COP was 3.5. The COP of the two-panel-unit condenser was lower than that of the air-cooled heat exchanger by 9% at an insolation of 442W/m{sup 2} but it rose to 12% in the absence of insolation. The COP of the two-panel-unit condenser was higher than that of a one-panel-unit condenser by 17%. When an insulator plate was attached to the back of a panel, the {Delta}t increased but the COP decreased by 14%. In the case of the series-connection condenser, the COP increased by 6% in the absence of the insulator plate. 2 refs., 9 figs.

  7. Studi Numerik Peningkatan Cooling Performance pada Lube Oil Cooler Gas Turbine yang Disusun Secara Seri dan Paralel dengan Variasi Kapasitas Aliran Lube Oil

    Directory of Open Access Journals (Sweden)

    Annis Khoiri Wibowo

    2014-09-01

    Full Text Available Salah satu komponen pada gas turbine adalah lube oil cooler yang berfungsi sebagai heat exchanger untuk mendinginkan temperatur lube oil. Pemasangan tiga lube oil cooler type-Z compact heat exchanger pada susunan seri dan paralel berdampak pada cooling capacity lube oil cooler. Uniformity flow rate pada masing-masing tube merupakan salah satu faktor yang mempengaruhi cooling capacity dari lube oil coole. Oleh karena itu dilakukan simulasi Computational Fluid Dynamic (CFD untuk mengkaji pengaruh pemasangan susunan tiga lube oil cooler secara seri dan paralel dengan variasi kapasitas lube oil terhadap performance lube oil cooler. Pemodelan domain dilakukan dengan 3 dimensi pada sisi eksternal dan internal. Simulasi pada sisi eksternal dilakukan untuk memperoleh nilai koefisien heat transfer pada masing-masing baris tube. Selanjutnya, nilai koefisien heat transfer yang didapat pada sisi eksternal digunakan sebagai kondisi batas wall convection pada masing-masing baris tube untuk simulasi internal flow dengan variasi flow rate lube oil 30 gpm, 50 gpm, 74 gpm. Dari hasil simulasi, susunan cooler seri menghasilkan cooling capacity yang lebih baik dari pada susunan cooler paralel pada kapasitas lube oil yang sama. Hal tersebut terjadi karena flow ratio lube oil untuk masing-masing tube pada susunan cooler seri lebih seragam dari pada susunan cooler paralel. Keseragaman flow rate pada masing-masing tube ditunjukkan dengan kecilnya standard deviasi flow ratio. Kapasitas 50 gpm memiliki standard deviasi flow ratio sebesar 0,46 untuk susunan seri dan 0,75 untuk susunan paralel. Semakin besar kapasitas lube oil maka distribusi flow rate pada masing-masing tube semakin tidak seragam. Selain itu susunan cooler seri memiliki pressure drop yang lebih besar dari pada susunan cooler paralel. Pemasangan susunan cooler dengan kapasitas 30 gpm memiliki tingkat keseragaman yang paling tinggi ditunjukkan dengan standard deviasi flow ratio pada masing-masing tube yang

  8. Simulated performance of CIEE's 'Alternatives to Compressive Cooling' prototype house under design conditions in various California climates

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yu Joe

    1999-12-01

    To support the design development of a compressorless house that does not rely on mechanical air-conditioning, the author carried out detailed computer analysis of a prototypical house design to determine the indoor thermal conditions during peak cooling periods for over 170 California locations. The peak cooling periods are five-day sequences at 2{percent} frequency determined through statistical analysis of long-term historical weather data. The DOE-2 program was used to simulate the indoor temperatures of the house under four operating options: windows closed, with mechanical ventilation, evaporatively-cooled mechanical ventilation, or a conventional 1 1/2-ton air conditioner. The study found that with a 1500 CFM mechanical ventilation system, the house design would maintain comfort under peak conditions in the San Francisco Bay Area out to Walnut Creek, but not beyond. In southern California, the same system and house design would maintain adequate comfort only along the coast. With the evaporatively-cooled ventilation system, the applicability of the house design can be extended to Fairfield and Livermore in northern California, but in southern California a larger 3000 CFM system would be needed to maintain comfort conditions over half of the greater Los Angeles area, the southern half of the Inland Empire, and most of San Diego county. With the 1 1/2-ton air conditioner, the proposed house design would perform satisfactorily through most of the state, except in the upper areas of the Central Valley and the hot desert areas in southern California. In terms of energy savings, the simulations showed that the prototypical house design would save from 0.20 to 0.43 in northern California, 0.20 to 0.53 in southern California, and 0.16 to 0.35 in the Central Valley, the energy used by the same house design built to Title-24 requirements.

  9. Fluidization technologies: Aerodynamic principles and process engineering.

    Science.gov (United States)

    Dixit, Rahul; Puthli, Shivanand

    2009-11-01

    The concept of fluidization has been adapted to different unit processes of pharmaceutical product development. Till date a lot of improvements have been made in the engineering design to achieve superior process performance. This review is focused on the fundamental principles of aerodynamics and hydrodynamics associated with the fluidization technologies. Fluid-bed coating, fluidized bed granulation, rotor processing, hot melt granulation, electrostatic coating, supercritical fluid based fluidized bed technology are highlighted. Developments in the design of processing equipments have been explicitly elucidated. This article also discusses processing problems from the operator's perspective along with latest developments in the application of these principles.

  10. Fundamentals of modern unsteady aerodynamics

    CERN Document Server

    Gülçat, Ülgen

    2016-01-01

    In this book, the author introduces the concept of unsteady aerodynamics and its underlying principles. He provides the readers with a comprehensive review of the fundamental physics of free and forced unsteadiness, the terminology and basic equations of aerodynamics ranging from incompressible flow to hypersonics. The book also covers modern topics related to the developments made in recent years, especially in relation to wing flapping for propulsion. The book is written for graduate and senior year undergraduate students in aerodynamics and also serves as a reference for experienced researchers. Each chapter includes ample examples, questions, problems and relevant references.   The treatment of these modern topics has been completely revised end expanded for the new edition. It now includes new numerical examples, a section on the ground effect, and state-space representation.

  11. Investigation of aerodynamic braking devices for wind turbine applications

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, D.A. [R. Lynette & amp; Associates, Seattle, WA (United States)

    1997-04-01

    This report documents the selection and preliminary design of a new aerodynamic braking system for use on the stall-regulated AWT-26/27 wind turbines. The goal was to identify and design a configuration that offered improvements over the existing tip brake used by Advanced Wind Turbines, Inc. (AWT). Although the design objectives and approach of this report are specific to aerodynamic braking of AWT-26/27 turbines, many of the issues addressed in this work are applicable to a wider class of turbines. The performance trends and design choices presented in this report should be of general use to wind turbine designers who are considering alternative aerodynamic braking methods. A literature search was combined with preliminary work on device sizing, loads and mechanical design. Candidate configurations were assessed on their potential for benefits in the areas of cost, weight, aerodynamic noise, reliability and performance under icing conditions. As a result, two configurations were identified for further study: the {open_quotes}spoiler-flap{close_quotes} and the {open_quotes}flip-tip.{close_quotes} Wind tunnel experiments were conducted at Wichita State University to evaluate the performance of the candidate aerodynamic brakes on an airfoil section representative of the AWT-26/27 blades. The wind tunnel data were used to predict the braking effectiveness and deployment characteristics of the candidate devices for a wide range of design parameters. The evaluation was iterative, with mechanical design and structural analysis being conducted in parallel with the braking performance studies. The preliminary estimate of the spoiler-flap system cost was $150 less than the production AWT-26/27 tip vanes. This represents a reduction of approximately 5 % in the cost of the aerodynamic braking system. In view of the preliminary nature of the design, it would be prudent to plan for contingencies in both cost and weight.

  12. Engineering models in wind energy aerodynamics: Development, implementation and analysis using dedicated aerodynamic measurements

    NARCIS (Netherlands)

    Schepers, J.G.

    2012-01-01

    The subject of aerodynamics is of major importance for the successful deployment of wind energy. As a matter of fact there are two aerodynamic areas in the wind energy technology: Rotor aerodynamics and wind farm aerodynamics. The first subject considers the flow around the rotor and the second subj

  13. Cooling of wood briquettes

    Directory of Open Access Journals (Sweden)

    Adžić Miroljub M.

    2013-01-01

    Full Text Available This paper is concerned with the experimental research of surface temperature of wood briquettes during cooling phase along the cooling line. The cooling phase is an important part of the briquette production technology. It should be performed with care, otherwise the quality of briquettes could deteriorate and possible changes of combustion characteristics of briquettes could happen. The briquette surface temperature was measured with an IR camera and a surface temperature probe at 42 sections. It was found that the temperature of briquette surface dropped from 68 to 34°C after 7 minutes spent at the cooling line. The temperature at the center of briquette, during the 6 hour storage, decreased to 38°C.

  14. Evaluation of a method for heat transfer measurements and thermal visualization using a composite of a heater element and liquid crystals. [thermal performance of turbine blade cooling configurations

    Science.gov (United States)

    Hippensteele, S. A.; Russell, L. M.; Stepka, F. S.

    1981-01-01

    Commercially available elements of a composite consisting of a plastic sheet coated with liquid crystal, another sheet with a thin layer of a conducting material (gold or carbon), and copper bus bar strips were evaluated and found to provide a simple, convenient, accurate, and low-cost measuring device for use in heat transfer research. The particular feature of the composite is its ability to obtain local heat transfer coefficients and isotherm patterns that provide visual evaluation of the thermal performances of turbine blade cooling configurations. Examples of the use of the composite are presented.

  15. Aerodynamics Research Revolutionizes Truck Design

    Science.gov (United States)

    2008-01-01

    During the 1970s and 1980s, researchers at Dryden Flight Research Center conducted numerous tests to refine the shape of trucks to reduce aerodynamic drag and improved efficiency. During the 1980s and 1990s, a team based at Langley Research Center explored controlling drag and the flow of air around a moving body. Aeroserve Technologies Ltd., of Ottawa, Canada, with its subsidiary, Airtab LLC, in Loveland, Colorado, applied the research from Dryden and Langley to the development of the Airtab vortex generator. Airtabs create two counter-rotating vortices to reduce wind resistance and aerodynamic drag of trucks, trailers, recreational vehicles, and many other vehicles.

  16. The aerodynamics of wind turbines

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming; Troldborg, Niels

    2013-01-01

    In the paper we present state-of-the-art of research in wind turbine aerodynamics. We start be giving a brief historical review and a survey over aerodynamic research in wind energy. Next, we focus on some recent research results obtained by our wind energy group at Department of Mechanical...... Engineering at DTU. In particular, we show some new results on the classical problem of the ideal rotor and present a series of new results from an on-going research project dealing with the modelling and simulation of turbulent flow structures in the wake behind wind turbines....

  17. Heat pump using dual heat sources of air and water. Performance in cooling mode; Mizu kuki ryonetsugen heat pump no kenkyu. Reibo unten ni okeru seino

    Energy Technology Data Exchange (ETDEWEB)

    Ito, S.; Miura, N. [Kanagawa Institute of Technology, Kanagawa (Japan); Uchikawa, Y. [Kubota Corp., Osaka (Japan)

    1997-11-25

    When a heat pump is used for cooling purpose, it is possible to utilize different kinds of waste water as high-heat sources. However, these heat sources would have their temperatures vary with seasons and time in a day. Therefore, a discussion was given on performance of a heat pump when water and air heat sources are used for condensers during cooling operation independently, in series and in parallel, respectively. The air condenser shows an equivalent COP as compared with the water condenser when air temperature is lower by about 8 degC than water temperature. At the same heat source temperature, the COP for the water condenser indicated a value higher by about 0.6 than the case of the air condenser. A method to use condensers in parallel experiences little contribution from the air heat source, and performance of the heat pump decreases below the case of using the water heat source independently when the air heat source temperature becomes higher than that of the water heat source. In the case of series use in which a water condenser is installed in front and an air condenser in rear, its effect is exhibited when temperature in the air heat source is lower than that in the water heat source. Better performance was shown than in operating the water heat source independently. 2 refs., 9 figs.

  18. 主要几何参数对叶栅式反推力装置性能的影响%Influence of cascade configuration on aerodynamic performance of a cascade thrust reverser

    Institute of Scientific and Technical Information of China (English)

    张国栋; 王强

    2012-01-01

    选取等厚叶栅进行数值模拟,采用混合网格生成技术,研究叶栅进口气流角、过渡段半径、叶片上下端轴向间距、稠密度和出口气流角对空气流量和轴向反推力的影响.计算结果表明:进口气流角、过渡段半径和叶片上下端轴向间距对风扇气流能否顺利导入叶栅起重要作用;稠密度影响着叶栅的出口面积和导流性能;出口气流角是反推力装置设计的关键因素,对反推性能起着决定性的作用.%The study chose equal-thickness shaped cascade blades, with the technology of hybrid grid system, and studied the influence of inlet flow angle, transition-radius, axial space between upside and underside of vane, solidity and outlet flow angle on the mass flow and axial reverser thrust. The final computation results show: the inlet flow angle, transi- tion-radius, axial space between upside and underside of vane play the important role in whether the fan flow inducts the cascade smoothly; the solidity affects the outlet area and diverted performance of cascade; the outlet flow angle is a key-factor of design of the cascade thrust reverser, so it gives direction to the aerodynamic performance of a cascade thrust re- verser.

  19. Study on the Influence of the Cold-End Cooling Water Thickness on the Generative Performance of TEG

    Science.gov (United States)

    Zhou, Li; Guo, Xuexun; Tan, Gangfeng; Ji, Kangping; Xiao, Longjie

    2016-11-01

    At present, about 40% of the fuel energy is discharged into air with the exhaust gas when an automobile is working, which is a big waste of energy. A thermoelectric generator (TEG) has the ability to harvest the waste heat energy in the exhaust gas. The traditional TEG cold-end is cooled by the engine cooling system, and although its structure is compact, the TEG weight and the space occupied are important factors restricting its application. In this paper, under the premise of ensuring the TEG maximum net output power and reducing the TEG water consumption as much as possible, the optimization of the TEG water thickness in the normal direction of the cold-end surface (WTNCS) is studied, which results in lighter weight, less space occupied and better automobile fuel economy. First, the thermal characteristics of the target diesel vehicle exhaust gas are evaluated based on the experimental data. Then, according to the thermoelectric generation model and the cold-end heat transfer model, the effect of the WTNCS on the cold-end temperature control stability and the system flow resistance are studied. The results show that the WTNCS influences the TEG cold-end temperature. When the engine works in a stable condition, the cold-end temperature decreases with the decrease of the WTNCS. The optimal value of the WTNCS is 0.02 m and the TEG water consumption is 8.8 L. Comparin it with the traditional vehicle exhaust TEG structure, the power generation increased slightly, but the water consumption decreased by about 39.5%, which can save fuel at0.18 L/h when the vehicle works at the speed of 60 km/h.

  20. 侧风风场特征对高速列车气动性能作用的研究%Research on Influence of Characteristics of Cross Wind Field on Aerodynamic Performance of a High-speed Train

    Institute of Scientific and Technical Information of China (English)

    毛军; 郗艳红; 杨国伟

    2011-01-01

    increase rapidly with increasing of the wind direction angle; when the train runs through the lower atmospheric boundary layer, compared to the uniform wind filed, the pressure differences of the train at the top & bottom and on two sides are less, the lateral force and overturning moment are also less, and the aerodynamic lift force is of uncertainty in the ease of increasing of the wind direction angle. Using the uniform wind field for evaluation of operation safety of high-speed trains running under cross winds on a plain will overestimate the risks cross winds may bring about in train operation and will over limit the train speed so that the normal train operation efficiency is affected. The lower atmospheric boundary layer winds are suggested to be used for evaluation of the aerodynamic performance of a train.