WorldWideScience

Sample records for vertical flat plate

  1. Fundamental Study of Local Heat Transfer in Forced Convective Boiling of Ammonia on Vertical Flat Plate

    Science.gov (United States)

    Kim, Jeong-Hun; Arima, Hirofumi; Ikegami, Yasuyuki

    In the present study, the fundamental experiments that investigate characteristics of local heat transfer in forced convective boiling on vertical flat plate with 2-mm channel height are taken to realize plate type compact evaporator for OTEC or STEC. The experiments are performed with ammonia as the working fluid. The experiments are also carried out with the following test conditions; saturated pressure = 0.7, 0.8, 0.9 MPa, mass flux = 7.5, 10, 15 kg/(m2•s), heat flux = 15, 20, 25 kW/m2 and inlet quality = 0.1 ~ 0.4 [-]. The result shows that the wall superheated temperature of forced convective boiling is lower than that of pool boiling. And the heat transfer coefficient increases with an increase in quality and the decrease in the local heat flux and saturated pressure for prescribed experimental conditions. However, local heat transfer coefficients are not affected by mass fluxes in the prescribed experimental conditions. An empirical correlation that can predict the local heat transfer coefficient on vertical flat plate within experimental conditions is also proposed.

  2. Natural Convection Flow along an Isothermal Vertical Flat Plate with Temperature Dependent Viscosity and Heat Generation

    Directory of Open Access Journals (Sweden)

    Md. Mamun Molla

    2014-01-01

    Full Text Available The purpose of this study is to investigate the natural convection laminar flow along an isothermal vertical flat plate immersed in a fluid with viscosity which is the exponential function of fluid temperature in presence of internal heat generation. The governing boundary layer equations are transformed into a nondimensional form and the resulting nonlinear system of partial differential equations is reduced to a convenient form which are solved numerically using an efficient marching order implicit finite difference method with double sweep technique. Numerical results are presented in terms of the velocity and temperature distribution of the fluid as well as the heat transfer characteristics, namely, the wall shear stress and the local and average rate of heat transfer in terms of the local skin-friction coefficient, the local and average Nusselt number for a wide range of the viscosity-variation parameter, heat generation parameter, and the Rayleigh number. Increasing viscosity variation parameter and Rayleigh number lead to increasing the local and average Nusselt number and decreasing the wall shear stress. Wall shear stress and the rate of heat transfer decreased due to the increase of heat generation.

  3. The Impact of Reduced Gravity on Free Convective Heat Transfer from a Finite, Flat, Vertical Plate

    Science.gov (United States)

    Lotto, Michael A.; Johnson, Kirstyn M.; Nie, Christopher W.; Klaus, David M.

    2017-09-01

    Convective heat transfer is governed by a number of factors including various fluid properties, the presence of a thermal gradient, geometric configuration, flow condition, and gravity. Empirically-derived analytical relationships can be used to estimate convection as a function of these governing parameters. Although it is relatively straightforward to experimentally quantify the contributions of the majority of these variables, it is logistically difficult to assess the influence of reduced-gravity due to practical limitations of establishing this environment. Therefore, in order to explore this regime, a series of tests was conducted to evaluate convection under reduced-gravity conditions averaging 0.45 m/sec2 (0.05 g) achieved aboard a parabolic aircraft. The results showed a reduction in net heat transfer of approximately 61% in flight relative to a 1g terrestrial baseline using the same setup. The average experimental Nusselt Number of 19.05 ± 1.41 statistically correlated with the predicted value of 18.90 ± 0.63 (N = 13), estimated using the Churchill-Chu correlation for free convective heat transfer from a finite, flat, vertical plate. Extrapolating this to similar performance in true microgravity (10-6 g) indicates that these conditions should yield a Nusselt Number of 1.27, which is 2.6% the magnitude of free convection at 1g, or a reduction of 97.4%. With advection essentially eliminated, heat transfer becomes limited to diffusion and radiation, which are gravity-independent and nearly equivalent in magnitude in this case. These results offer a general guideline for integrating components that utilize natural (free) convective gas cooling in a spacecraft habitat and properly sizing the thermal control system.

  4. The Impact of Reduced Gravity on Free Convective Heat Transfer from a Finite, Flat, Vertical Plate

    Science.gov (United States)

    Lotto, Michael A.; Johnson, Kirstyn M.; Nie, Christopher W.; Klaus, David M.

    2017-10-01

    Convective heat transfer is governed by a number of factors including various fluid properties, the presence of a thermal gradient, geometric configuration, flow condition, and gravity. Empirically-derived analytical relationships can be used to estimate convection as a function of these governing parameters. Although it is relatively straightforward to experimentally quantify the contributions of the majority of these variables, it is logistically difficult to assess the influence of reduced-gravity due to practical limitations of establishing this environment. Therefore, in order to explore this regime, a series of tests was conducted to evaluate convection under reduced-gravity conditions averaging 0.45 m/sec2 (0.05 g) achieved aboard a parabolic aircraft. The results showed a reduction in net heat transfer of approximately 61% in flight relative to a 1 g terrestrial baseline using the same setup. The average experimental Nusselt Number of 19.05 ± 1.41 statistically correlated with the predicted value of 18.90 ± 0.63 (N = 13), estimated using the Churchill-Chu correlation for free convective heat transfer from a finite, flat, vertical plate. Extrapolating this to similar performance in true microgravity (10-6 g) indicates that these conditions should yield a Nusselt Number of 1.27, which is 2.6% the magnitude of free convection at 1 g, or a reduction of 97.4%. With advection essentially eliminated, heat transfer becomes limited to diffusion and radiation, which are gravity-independent and nearly equivalent in magnitude in this case. These results offer a general guideline for integrating components that utilize natural (free) convective gas cooling in a spacecraft habitat and properly sizing the thermal control system.

  5. Combined Effects Of Stress Work And Heat Generation On MHD Natural Convection Flow Along A Vertical Flat Plate With Power Law Variation Of Uniform Surface Temperature

    National Research Council Canada - National Science Library

    Mohammad Mahfuzul Islam; Md. M. Alam; M. M. Parvez; M. A. Rahman

    2015-01-01

    Abstract In this paper is presented to study conjugate effects of stress work and heat generation on MHD natural convection flow along a vertical flat plate with power law variation of surface temperature...

  6. MHD Natural Convection Flow of an incompressible electrically conducting viscous fluid through porous medium from a vertical flat plate

    Directory of Open Access Journals (Sweden)

    Dr. G. Prabhakara Rao,

    2015-04-01

    Full Text Available We consider a two-dimensional MHD natural convection flow of an incompressible viscous and electrically conducting fluid through porous medium past a vertical impermeable flat plate is considered in presence of a uniform transverse magnetic field. The governing equations of velocity and temperature fields with appropriate boundary conditions are solved by the ordinary differential equations by introducing appropriate coordinate transformations. We solve that ordinary differential equations and find the velocity profiles, temperature profile, the skin friction and nusselt number. The effects of Grashof number (Gr, Hartmann number (M and Prandtl number (Pr, Darcy parameter (D-1 on velocity profiles and temperature profiles are shown graphically.

  7. Double diffusive magnetohydrodynamic (MHD) mixed convective slip flow along a radiating moving vertical flat plate with convective boundary condition.

    Science.gov (United States)

    Rashidi, Mohammad M; Kavyani, Neda; Abelman, Shirley; Uddin, Mohammed J; Freidoonimehr, Navid

    2014-01-01

    In this study combined heat and mass transfer by mixed convective flow along a moving vertical flat plate with hydrodynamic slip and thermal convective boundary condition is investigated. Using similarity variables, the governing nonlinear partial differential equations are converted into a system of coupled nonlinear ordinary differential equations. The transformed equations are then solved using a semi-numerical/analytical method called the differential transform method and results are compared with numerical results. Close agreement is found between the present method and the numerical method. Effects of the controlling parameters, including convective heat transfer, magnetic field, buoyancy ratio, hydrodynamic slip, mixed convective, Prandtl number and Schmidt number are investigated on the dimensionless velocity, temperature and concentration profiles. In addition effects of different parameters on the skin friction factor, [Formula: see text], local Nusselt number, [Formula: see text], and local Sherwood number [Formula: see text] are shown and explained through tables.

  8. Mixed convection boundary layer flow over a moving vertical flat plate in an external fluid flow with viscous dissipation effect.

    Directory of Open Access Journals (Sweden)

    Norfifah Bachok

    Full Text Available The steady boundary layer flow of a viscous and incompressible fluid over a moving vertical flat plate in an external moving fluid with viscous dissipation is theoretically investigated. Using appropriate similarity variables, the governing system of partial differential equations is transformed into a system of ordinary (similarity differential equations, which is then solved numerically using a Maple software. Results for the skin friction or shear stress coefficient, local Nusselt number, velocity and temperature profiles are presented for different values of the governing parameters. It is found that the set of the similarity equations has unique solutions, dual solutions or no solutions, depending on the values of the mixed convection parameter, the velocity ratio parameter and the Eckert number. The Eckert number significantly affects the surface shear stress as well as the heat transfer rate at the surface.

  9. MHD Free Convective Boundary Layer Flow of a Nanofluid past a Flat Vertical Plate with Newtonian Heating Boundary Condition

    Science.gov (United States)

    Uddin, Mohammed J.; Khan, Waqar A.; Ismail, Ahmed I.

    2012-01-01

    Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement. PMID:23166688

  10. MHD free convective boundary layer flow of a nanofluid past a flat vertical plate with Newtonian heating boundary condition.

    Science.gov (United States)

    Uddin, Mohammed J; Khan, Waqar A; Ismail, Ahmed I

    2012-01-01

    Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement.

  11. MHD free convective boundary layer flow of a nanofluid past a flat vertical plate with Newtonian heating boundary condition.

    Directory of Open Access Journals (Sweden)

    Mohammed J Uddin

    Full Text Available Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement.

  12. Combined Effects Of Stress Work And Heat Generation On MHD Natural Convection Flow Along A Vertical Flat Plate With Power Law Variation Of Uniform Surface Temperature

    Directory of Open Access Journals (Sweden)

    Mohammad Mahfuzul Islam

    2015-08-01

    Full Text Available Abstract In this paper is presented to study conjugate effects of stress work and heat generation on MHD natural convection flow along a vertical flat plate with power law variation of surface temperature. Stress work and heat generation effects on magneto-hydrodynamics natural convection flows are considered in this investigation. With a goal to attain similarity solutions of the problem the developed equations are made dimensionless by using suitable transformations. The non-dimensional equations are then transformed into non-similar forms by introducing non- similarity transformations. The resulting non-similar equations together with their corresponding boundary conditions based on conduction and convection are solved numerically by using the shooting method of Nachtsheim-swigert iteration technique and finite difference method together with Keller box Scheme. Numerically calculated velocity profiles and temperature profiles skin friction and the rate of heat transfer coefficient are shown on graphs for different values of the parameters entering into the problem.

  13. Mixed Convection Boundary Layer Stagnation-Point Flow of a Jeffery Fluid Past a Permeable Vertical Flat Plate

    Science.gov (United States)

    Rahman, Mohammad M.; Ioan, Pop

    2014-12-01

    This paper analyzes the combined effects of buoyancy force, mass flux, and variable surface temperature on the stagnation point flow and heat transfer due to a Jeffery fluid over a vertical surface. The governing nonlinear partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations using similarity transformations and then solved numerically using the function bvp4c from computer algebra software Matlab. Numerical results are obtained for skin friction coefficient, Nusselt number as well as dimensionless velocity and temperature profiles for various values of the controlling parameters namely mixed convection parameter λ, mass flux parameter s, elastic parameter (Deborah number) γ, and the ratio of relaxation and retardation time parameter λ1. The results indicate that dual solutions exist in a certain range of the mixed convection and mass flux parameters. In order to establish the physically realizable of these solutions, a stability analysis has also been performed. The results indicate that mixed convection and mass flux significantly affects the nature of the solutions, skin friction, and Nusselt number of a Jeffery fluid.

  14. High performance flat plate solar collector

    Science.gov (United States)

    Lansing, F. L.; Reynolds, R.

    1976-01-01

    The potential use of porous construction is presented to achieve efficient heat removal from a power producing solid and is applied to solar air heaters. Analytical solutions are given for the temperature distribution within a gas-cooled porous flat plate having its surface exposed to the sun's energy. The extracted thermal energy is calculated for two different types of plate transparency. Results show the great improvement in performance obtained with porous flat plate collectors as compared with analogous nonporous types.

  15. Fabrication of Flat Plate Solar Geyser with Flat Grooved Heat Exchanger Having Special Exit System

    OpenAIRE

    Malik, Muhammad Suleman; Malik, Muhammad Arsalan; Shah, Haseeb Ali; Khan Afridi, Adnan Anwar; Asif, Muhammad

    2017-01-01

    International audience; The main objective of this paper is to introduce the concept of novel flat plate solar geyser with integrated heat exchanger and open loop passive system.The heat exchanger acts both as collector for solar radiations and as a heat exchanger its self for cold water beneath it. Contrary to the conventional flat plate solar collectors, water is in direct contact with the collector or flat grooved heat exchanger. A safety control box is installed to minimize hydraulic pres...

  16. Surgical treatment of intraarticular fractures of the calcaneus: comparison between flat plate and calcaneal plate

    Directory of Open Access Journals (Sweden)

    Luiz Carlos Almeida da Silva

    Full Text Available ABSTRACT OBJECTIVE: To evaluate the clinical results of surgical treatment of intraarticular fractures of the calcaneus, comparing the use of calcaneal plate and flat plate. METHODS: This was a retrospective study assessing the postoperative results of 25 patients between 2013 and 2015. Patients undergoing surgical treatment of intraarticular fractures of the calcaneus without concomitant surgical lesions were included. Patients who did not complete appropriate follow-up after surgery were excluded from the study. RESULTS: The unavailability of calcaneal plates at resource-limited settings, associated with the availability and lower cost of flat plates, may have been a confounding factor in the present study. However, there was no statistical difference between the outcomes of fractures treated with calcaneal plates or flat plates. CONCLUSION: Statistical inference shows that, when calcaneal plates are not available, it is possible to use flat plates with similar clinical outcomes.

  17. Detailed Modeling of Flat Plate Solar Collector with Vacuum Glazing

    OpenAIRE

    Viacheslav Shemelin; Tomas Matuska

    2017-01-01

    A theoretical analysis of flat plate solar collectors with a vacuum glazing is presented. Different configurations of the collector have been investigated by a detailed theoretical model based on a combined external and internal energy balance of the absorber. Performance characteristics for vacuum flat plate collector alternatives have been derived. Subsequently, annual energy gains have been evaluated for a selected variant and compared with state-of-the-art vacuum tube collectors. The resu...

  18. Asymptotics and Numerics for Laminar Flow over Finite Flat Plate

    NARCIS (Netherlands)

    Dijkstra, D.; Kuerten, J.G.M.; Kaper, Hans G.; Garbey, Mare; Pieper, Gail W.

    1992-01-01

    A compilation of theoretical results from the literature on the finite flat-plate flow at zero incidence is presented. This includes the Blasius solution, the Triple Deck at the trailing edge, asymptotics in the wake, and properties near the edges of the plate. In addition, new formulas for skin

  19. Dynamic Modeling of Natural Convection Solar Energy Flat Plate ...

    African Journals Online (AJOL)

    The analytical solutions to the dynamic model of an air-heating flat plate solar energy thermal collector were validated by direct measurement from a physical model constructed for that purpose, of the temperatures of the cover and absorber plates, the inlet and outlet fluids, and the ambient air from morning to evening for ...

  20. Fabrication of Flat Plate Solar Geyser with Flat Grooved Heat Exchanger Having Special Exit System

    OpenAIRE

    Muhammad Suleman Malik; Muhammad Arsalan Malik; Haseeb Ali Shah; Adnan Anwar khan afridi; Muhammad Asif

    2017-01-01

    The main objective of this paper is to introduce the concept of novel flat plate solar geyser with integrated heat exchanger and open loop passive system.The heat exchanger acts both as collector for solar radiations and as a heat exchanger its self for cold water beneath it. Contrary to the conventional flat plate solar collectors, water is in direct contact with the collector or flat grooved heat exchanger. A safety control box is installed to minimize hydraulic pressure of cold water rese...

  1. Impingement of Supersonic Jets on Inclined Flat Plate

    OpenAIRE

    望月, 博昭; 宮里, 義昭; 佐藤, 義智; 松尾, 一泰

    1993-01-01

    Flow fields of supersonic axisymmetric jets impinging on an inclined flat plate are experimentally studied by flow visualization with Schlieren method and pressure measurements on the plate. The experiments are carried out for plate inclinations of 22.5° and 30° and for six nozzles with Mach numbers from 1.0 to 4.07. The distances from the nozzle exit to the impingement point of jet on the plate is fixed at 43 mm. The effects of locations of shock cells on the flow state, the pressure distrib...

  2. Normal pressure tests on unstiffened flat plates

    Science.gov (United States)

    Head, Richard M; Sechler, Ernest J

    1944-01-01

    Flat sheet panels of aluminum alloy (all 17S-T except for two specimens of 24S-T) were tested under normal pressures with clamped edge supports in the structures laboratory of the Guggenheim Aeronautical Laboratory, California Institute of Technology. The thicknesses used ranged from 0.010 to 0.080 inch; the panel sizes ranged from 10 by 10 inches to 10 by 40 inches; and the pressure range was from 0 to 60-pounds-per-square-inch gage. Deflection patterns were measured and maximum tensile strains in the center of the panel were determined by electric strain gages. The experimental data are presented by pressure-strain, pressure-maximum-deflection, and pressure-deflection curves. The results of these tests have been compared with the corresponding strains and deflections as calculated by the simple membrane theory and by large deflection theories.

  3. Flat Plate Reduction in a Water Tunnel Using Riblets

    Science.gov (United States)

    1987-05-01

    Cononue onreee dnaessey end defyy blod numbr) FIEL / 9 GROUP SUB.GROUP Drag reduction /inTurbulent boundary layer // Streamwie microgroove surface...and its leading edge were separately constructed from type 302 stainless steel. The flat plate is 19.0mm thick and -.0.58m wide. with an Overall

  4. Certification and verification for calmac flat plate solar collector

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-27

    This document contains information used in the certification and verification of the Calmac Flat Plate Collector. Contained are such items as test procedures and results, information on materials used, Installation, Operation, and Maintenance Manuals, and other information pertaining to the verification and certification.

  5. Weathering of a flat-plate solar collector

    Science.gov (United States)

    1980-01-01

    Report contains performance evaluation of flat-plate liquid solar collector after 14-months of natural weathering. Collector efficiency was calculated and plotted as function of inlet liquid temperature. Measurements were made of ambient temperature, inlet and outlet temperatures, differential temperature and pressure, liquid flow rate, insolation, and windspeed.

  6. An experimental study of an explosively driven flat plate launcher

    Science.gov (United States)

    Rae, Philip; Haroz, Erik; Armstrong, Chris; Perry, Lee; M Division Team

    2017-06-01

    For some upcoming experiments it is desired to impact a large explosive assembly with one or more moderate diameter flat metal plates traveling at high velocity (2-3 km s-1). The time of arrival of these plates will need to carefully controlled and delayed (i.e. the time(s) of arrival known to approximately a microsecond). For this reason, producing a flyer plate from more traditional gun assemblies is not possible. Previous researchers have demonstrated the ability to throw reasonably flat metal flyers from the so-called Forest flyer geometry. The defining characteristics of this design are a carefully controlled reduction in explosive area from a larger explosive plane-wave-lens and booster pad to a smaller flyer plate to improve the planarity of the drive available and an air gap between the explosive booster and the plate to reduce the peak tensile stresses generated in the plate to suppress spalling. This experimental series comprised a number of different design variants and plate and explosive drive materials. The aim was to calibrate a predictive computational modeling capability on this kind of system in preparation for later more radical design ideas best tested in a computer before undertaking the expensive business of construction.

  7. Unsteady Reversed Stagnation-Point Flow over a Flat Plate

    OpenAIRE

    Sin, Vai Kuong; Chio, Chon Kit

    2012-01-01

    This paper investigates the nature of the development of two-dimensional laminar flow of an incompressible fluid at the reversed stagnation-point. ". In this study, we revisit the problem of reversed stagnation-point flow over a flat plate. Proudman and Johnson (1962) first studied the flow and obtained an asymptotic solution by neglecting the viscous terms. This is no true in neglecting the viscous terms within the total flow field. In particular it is pointed out that for a plate impulsivel...

  8. Detailed Modeling of Flat Plate Solar Collector with Vacuum Glazing

    Directory of Open Access Journals (Sweden)

    Viacheslav Shemelin

    2017-01-01

    Full Text Available A theoretical analysis of flat plate solar collectors with a vacuum glazing is presented. Different configurations of the collector have been investigated by a detailed theoretical model based on a combined external and internal energy balance of the absorber. Performance characteristics for vacuum flat plate collector alternatives have been derived. Subsequently, annual energy gains have been evaluated for a selected variant and compared with state-of-the-art vacuum tube collectors. The results of modeling indicate that, in the case of using advanced vacuum glazing with optimized low-emissivity coating (emissivity 0.20, solar transmittance 0.85, it is possible to achieve efficiency parameters similar to or even better than vacuum tube collectors. The design presented in this paper can be considered promising for the extension of the applicability range of FPC and could be used in applications, which require low-to-medium temperature level.

  9. Evaluation of Shear Strength of Concrete Flat Plates Reinforced with GFRP Plates

    Directory of Open Access Journals (Sweden)

    Min Sook Kim

    2017-01-01

    Full Text Available The shear performance of concrete flat plates with glass fiber-reinforced polymer (GFRP plate shear reinforcement was investigated through punching shear tests. Each GFRP plate was embedded in the concrete and included openings to permit the flow of concrete during fabrication. Punching shear tests were conducted on a total of 8 specimens, and the resulting crack and fracture formations, strains, and load-displacement curves were analyzed and compared. The experimental variables considered were the types of shear reinforcement, including steel stirrups or GFRP plates, and the shear reinforcement spacing. The experimental results show that the GFRP shear reinforcement effectively increased the shear strengths of flat plates. Furthermore, the applicability of two formulas was investigated: a modified version of a shear strength formula from ACI 318-14 and the ACI 318-14 fracture prediction formula.

  10. 78 FR 31577 - Diffusion-Annealed, Nickel-Plated Flat-Rolled Steel Products From Japan

    Science.gov (United States)

    2013-05-24

    ...)] Diffusion-Annealed, Nickel-Plated Flat-Rolled Steel Products From Japan Determination On the basis of the... reason of imports from Japan of diffusion-annealed, nickel-plated flat-rolled steel products, provided... diffusion-annealed, nickel-plated flat-rolled steel products from Japan. Accordingly, effective March 27...

  11. Buckling of Flat Thin Plates under Combined Loading

    Directory of Open Access Journals (Sweden)

    Ion DIMA

    2015-03-01

    Full Text Available This article aims to provide a quick methodology to determine the critical values of the forces applied to the central plane of a flat isotropic plate at which a change to the stable configuration of equilibrium occurs. Considering the variety of shapes, boundary conditions and loading combinations, the article does not intend to make an exhaustive presentation of the plate buckling. As an alternative, there will be presented only the most used configurations such as: rectangular flat thin plates, boundary conditions with simply supported (hinged or clamped (fixed edges, combined loadings with single compression or single shear or combination between them, compression and shear, with or without transverse loading, encountered at wings and control surfaces shell of fin and rudder or stabilizer and elevator. The reserve factor and the critical stresses will be calculated using comparatively two methods, namely the methodology proposed by the present article and ASSIST 6.6.2.0 – AIRBUS France software, a dedicated software to local calculations, for a simply supported plate under combined loading, compression on the both sides and shear.

  12. Scattering and trapping of vortex pairs by a flat plate

    Science.gov (United States)

    Nitsche, Monika

    2017-11-01

    The interaction of a counter-rotating vortex pair with a flat plate in its path is studied numerically. The vortices are initially separated by a distance D and placed far upstream of a plate of length L. The plate is stationary, inclined relative to the incoming vortex trajectory, at an incident angle βi. Generally, the vortices surround the plate and then leave as a dipole with unchanged velocity, but with a large change in the transmitted travel direction. This transmitted angle depends sensitively on changes in the incident angle, with increasing sensitivity as D / L decreases. In fact, for sufficiently small D / L , the dependence on βi is highly singular. We show that there are intervals of incident angles in which the vortex trajectory undergoes repeated topological discontinuities, characterized by jumps in the vortex winding number and in the time they take to leave the plate. The discontinuities occur in a fractal self-similar fashion within the whole interval. These intervals furthermore contain incident angles that trap the vortices, which never leave the plate. The number of such trapping intervals increases as the parameter D / L decreases, and the dependence of the motion on βi becomes increasing complex.

  13. A high performance porous flat-plate solar collector

    Science.gov (United States)

    Lansing, F. L.; Clarke, V.; Reynolds, R.

    1979-01-01

    A solar collector employing a porous matrix as a solar absorber and heat exchanger is presented and its application in solar air heaters is discussed. The collector is composed of a metallic matrix with a porous surface which acts as a large set of cavity radiators; cold air flows through the matrix plate and exchanges heat with the thermally stratified layers of the matrix. A steady-state thermal analysis of the collector is used to determine collector temperature distributions for the cases of an opaque surface matrix with total absorption of solar energy at the surface, and a diathermanous matrix with successive solar energy absorption at each depth. The theoretical performance of the porous flat plate collector is shown to exceed greatly that of a solid flat plate collector using air as the working medium for any given set of operational conditions. An experimental collector constructed using commercially available, low cost steel wool as the matrix has been found to have thermal efficiencies from 73 to 86%.

  14. Heat transfer in porous medium embedded with vertical plate: Non-equilibrium approach - Part A

    Energy Technology Data Exchange (ETDEWEB)

    Badruddin, Irfan Anjum [Dept. of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Quadir, G. A. [School of Mechatronic Engineering, University Malaysia Perlis, Pauh Putra, 02600 Arau, Perlis (Malaysia)

    2016-06-08

    Heat transfer in a porous medium embedded with vertical flat plate is investigated by using thermal non-equilibrium model. Darcy model is employed to simulate the flow inside porous medium. It is assumed that the heat transfer takes place by natural convection and radiation. The vertical plate is maintained at isothermal temperature. The governing partial differential equations are converted into non-dimensional form and solved numerically using finite element method. Results are presented in terms of isotherms and streamlines for various parameters such as heat transfer coefficient parameter, thermal conductivity ratio, and radiation parameter.

  15. Efficiencies of flat plate solar collectors at different flow rates

    DEFF Research Database (Denmark)

    Chen, Ziqian; Furbo, Simon; Perers, Bengt

    2012-01-01

    Two flat plate solar collectors for solar heating plants from Arcon Solvarme A/S are tested in a laboratory test facility for solar collectors at Technical University of Denmark (DTU). The collectors are designed in the same way. However, one collector is equipped with an ETFE foil between...... the absorber and the cover glass and the other is without ETFE foil. The efficiencies for the collectors are tested at different flow rates. On the basis of the measured efficiencies, the efficiencies for the collectors as functions of flow rate are obtained. The calculated efficiencies are in good agreement...

  16. Calculating the Solar Energy of a Flat Plate Collector

    Directory of Open Access Journals (Sweden)

    Ariane Rosario

    2014-09-01

    Full Text Available The amount of solar energy that could be obtained by a flat plate solar collector of one square meter dimension is calculated in three different locations: Tampa FL, Fairbanks AL, and Pontianak Indonesia, considering the varying sunset time for each day of the year. The results show that if the collectors are placed near the equator, more total energy could be obtained. In fact, by placing a solar collector in Pontianak, Indonesia 12.42% more solar energy can be obtained than by placing it in Tampa and 96.9% more solar energy than Alaska.

  17. High Performance Flat Plate Solar Thermal Collector Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Rockenbaugh, Caleb [National Renewable Energy Lab. (NREL), Golden, CO (United States); Dean, Jesse [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lovullo, David [National Renewable Energy Lab. (NREL), Golden, CO (United States); Lisell, Lars [National Renewable Energy Lab. (NREL), Golden, CO (United States); Barker, Greg [National Renewable Energy Lab. (NREL), Golden, CO (United States); Hanckock, Ed [National Renewable Energy Lab. (NREL), Golden, CO (United States); Norton, Paul [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-09-01

    This report was prepared for the General Services Administration by the National Renewable Energy Laboratory. The Honeycomb Solar Thermal Collector (HSTC) is a flat plate solar thermal collector that shows promising high efficiencies over a wide range of climate zones. The technical objectives of this study are to: 1) verify collector performance, 2) compare that performance to other market-available collectors, 3) verify overheat protection, and 4) analyze the economic performance of the HSTC both at the demonstration sites and across a matrix of climate zones and utility markets.

  18. Experiments to investigate lift production mechanisms on pitching flat plates

    Science.gov (United States)

    Stevens, P. R. R. J.; Babinsky, H.

    2017-01-01

    Pitching flat plates are a useful simplification of flapping wings, and their study can provide useful insights into unsteady force generation. Non-circulatory and circulatory lift producing mechanisms for low Reynolds number pitching flat plates are investigated. A series of experiments are designed to measure forces and study the unsteady flowfield development. Two pitch axis positions are investigated, namely a leading edge and a mid-chord pitch axis. A novel PIV approach using twin laser lightsheets is shown to be effective at acquiring full field of view velocity data when an opaque wing model is used. Leading-edge vortex (LEV) circulations are extracted from velocity field data, using a Lamb-Oseen vortex fitting algorithm. LEV and trailing-edge vortex positions are also extracted. It is shown that the circulation of the LEV, as determined from PIV data, approximately matches the general trend of an unmodified Wagner function for a leading edge pitch axis and a modified Wagner function for a mid-chord pitch axis. Comparison of experimentally measured lift correlates well with the prediction of a reduced-order model for a LE pitch axis.

  19. Sintered Nickel Powder Wicks for Flat Vertical Heat Pipes

    Directory of Open Access Journals (Sweden)

    Geir Hansen

    2015-03-01

    Full Text Available The fabrication and performance of wicks for flat heat pipe applications produced by sintering a filamentary nickel powder has been investigated. Tape casting was used as an intermediate step in the wick production process. Thermogravimetric analysis was used to study the burn-off of the organic binder used and to study the oxidation and reduction processes of the nickel. The wicks produced were flat, rectangular and intended for liquid transport in the upwards vertical direction. Rate-of-rise experiments using heptane were used to test the flow characteristics of the wicks. The wick porosities were measured using isopropanol. The heat transfer limitation constituted by the vapour static pressure and the capillary pressure was discussed. The influence on wick performance by using pore former in the manufacturing was studied. When Pcap/Psat > 1, the use of a pore former to increase the wick permeability will always improve the wick performance. When Pcap/Psat < 1, it was shown that if the effective pore radius and the permeability increase with an equal percentage the overall influence on the wick capacity is negative. A criterion for a successful pore former introduction is proposed and the concept of a pore former evaluation plot is presented.

  20. Vortex Formation Behind an Inclined 2-Dimensional Thin Flat Plate

    Science.gov (United States)

    Mohebi, Meraj; Wood, David H.; Martinuzzi, Robert J.

    2014-11-01

    Stereo Particle Image Velocimetry was used to measure the turbulent wake of a 2D flat plate inclined relative to a uniform stream as a heuristic model for airfoils and wind turbine blades at high incidence. Phase Averaging was performed to study the vortex dynamics and relate these to the force characteristics. Below 90°, immediately behind the plate, rounder and more organized trailing edge vortices form which possess higher circulation and are associated with higher Reynolds stresses than the counter-rotating, weaker and elongated leading edge vortices. The quasi-periodically shed vortices on the sides of the wake decay in strength at different rates to reach a circulation ratio of -1 within a distance less than 5 chords downstream of the plate for all angles. This equalization of vortex strength is related to an increase in turbulence diffusion, due to mostly-incoherent 3-dimensionality which progressively increases as the inclination angle is reduced, and convective transfer of vorticity between counter-rotating vortices. The wake experiences a sudden change in vortex formation mechanism at around 40°. At this angle, the frequency analysis on the signals of a pair of micro-pressure transducers in the wake also shows a discontinuity in the trends. This work was supported by NSERC Discovery grants to R. J. Martinuzzi and D. H. Wood.

  1. An investigation on the performance characteristics of solar flat plate collector with different selective surface coatings

    OpenAIRE

    Madhukeshwara N., E. S. Prakash

    2012-01-01

    In the present work, investigations are made to study performance characteristics of solar flat plate collector with different selective surface coatings. Flat plate collector is one of the important solar energy trapping device which uses air or water as working fluid. Of the many solar collector concepts presently being developed, the relative simple flat plate solar collector has found the widest application so far. Its characteristics are known, and compared with other collector types, it...

  2. DESIGN AND THERMAL ANALYSIS OF FIXED AND TRACKING FLAT PLATE COLLECTORS

    OpenAIRE

    *Sudarshan T A

    2016-01-01

    This paper focuses on Thermal efficiency analysis of flat plate collectors. The instantaneous efficiency for a collector over a day is calculated. Application of solar energy for domestic and industrial heating purposes has been become very popular. However the effectiveness of presently used fixed flat plate collectors is low due to the moving nature of the energy source. In the present work, an attempt has been made to compare the performance of fixed flat plate water heater with that of he...

  3. Flat-plate boiloff calorimeters for testing of thermal insulation systems

    Science.gov (United States)

    Fesmire, J. E.; Johnson, W. L.; Kelly, A. O.; Meneghelli, B. J.; Swanger, A. M.

    2015-12-01

    Cryostats have been developed and standardized for laboratory testing of thermal insulation systems in a flat-plate configuration. Boiloff calorimetry is the measurement principle for determining the effective thermal conductivity (ke) and heat flux (q) of test specimens under a wide range of actual conditions. Cryostat-500 is thermally guarded to measure absolute thermal performance when calibrated with a known reference via an adjustable-edge guard ring. With liquid nitrogen as the energy meter, the cold boundary temperature can be adjusted to any temperature between 77 K and approximately 300 K by the interposition of a thermal resistance layer between the cold mass and the specimen. A low thermal conductivity suspension system has compliance rods that adjust for specimen thickness and compression force. Material type, thickness, density, flatness, compliance, outgassing, and temperature sensor placement are important test considerations, and edge effects and calibration techniques for the apparatus are crucial. Over the full vacuum pressure range, the thermal performance capability is nearly four orders of magnitude. The horizontal configuration provides key advantages over the vertical cylindrical cryostats for testing at ambient pressure conditions. Cryostat-500’s design and test methods, other flat-plate boiloff calorimeters, and results for select thermal insulation materials (composites, foams, aerogels) are discussed.

  4. Wind loads on flat plate photovoltaic array fields (nonsteady winds)

    Science.gov (United States)

    Miller, R. D.; Zimmerman, D. K.

    1981-01-01

    Techniques to predict the dynamic response and the structural dynamic loads of flat plate photovoltaic arrays due to wind turbulence were analyzed. Guidelines for use in predicting the turbulent portion of the wind loading on future similar arrays are presented. The dynamic response and the loads dynamic magnification factor of the two array configurations are similar. The magnification factors at a mid chord and outer chord location on the array illustrated and at four points on the chord are shown. The wind tunnel test experimental rms pressure coefficient on which magnification factors are based is shown. It is found that the largest response and dynamic magnification factor occur at a mid chord location on an array and near the trailing edge. A technique employing these magnification factors and the wind tunnel test rms fluctuating pressure coefficients to calculate design pressure loads due to wind turbulence is presented.

  5. System Advisor Model: Flat Plate Photovoltaic Performance Modeling Validation Report

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, Janine [National Renewable Energy Lab. (NREL), Golden, CO (United States); Whitmore, Jonathan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kaffine, Leah [National Renewable Energy Lab. (NREL), Golden, CO (United States); Blair, Nate [National Renewable Energy Lab. (NREL), Golden, CO (United States); Dobos, Aron P. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2013-12-01

    The System Advisor Model (SAM) is a free software tool that performs detailed analysis of both system performance and system financing for a variety of renewable energy technologies. This report provides detailed validation of the SAM flat plate photovoltaic performance model by comparing SAM-modeled PV system generation data to actual measured production data for nine PV systems ranging from 75 kW to greater than 25 MW in size. The results show strong agreement between SAM predictions and field data, with annualized prediction error below 3% for all fixed tilt cases and below 8% for all one axis tracked cases. The analysis concludes that snow cover and system outages are the primary sources of disagreement, and other deviations resulting from seasonal biases in the irradiation models and one axis tracking issues are discussed in detail.

  6. Application of solar flat plate collector in automobile industry

    Energy Technology Data Exchange (ETDEWEB)

    Wawge, P. [Peenya Alloys Pvt. Ltd., Parvati, Pune (India)

    2004-07-01

    In any industry, heating, cooling and compressed air the costliest part, which affects the production cost of any product. There are three types of indirect heat requirement or the requirement of heat can be divided in the three main categories. (1) low temp. 40 - 60 Deg. (2) Medium temp. 80 - 150 deg. (3) High Temp applications - above 150. Solar Flat Collectors have been proven for the use of solar energy for medium temp. application in hotels, boiler feed water preheating, dairy for pasteurization and some other indirect heating applications. There is another neglected area of application of Solar Flat Plate collector is heat treatment for powder coating plants where heat requirement is bet 50 Deg C - 70 Deg C. In any automobile industry the aesthetic or look of the vehicle place a very important role as far as the sale is concern (after the mechanical performance). The aesthetic means the body and colour of the vehicle. To get a long lasting good quality color, the powder coating procedure plays a major role. Before powder coating there is requirement of different chemical treatment for the removal of rust, grease and other cleaning of the specific sheet metal body parts. The time duration and chemical composition is depends on the selection of body material. A proven method of a chemical treatment is seven / eight tank process. The common system of heating chemicals is by way of electrical heaters, by diesel or other fuel fired boilers. This increases the cost of heat treatment process due the high cost of electricity (for industries rate of electricity is 1.5 to 2 times than the domestic rate) or oils. This can be replaced by Solar water heating system which can efficiently generate the temp of liquid upto 85 Deg C. (orig.)

  7. Wind loads on flat plate photovoltaic array fields

    Science.gov (United States)

    Miller, R. D.; Zimmerman, D. K.

    1981-01-01

    The results of an experimental analysis (boundary layer wind tunnel test) of the aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays are presented. Local pressure coefficient distributions and normal force coefficients on the arrays are shown and compared to theoretical results. Parameters that were varied when determining the aerodynamic forces included tilt angle, array separation, ground clearance, protective wind barriers, and the effect of the wind velocity profile. Recommended design wind forces and pressures are presented, which envelop the test results for winds perpendicular to the array's longitudinal axis. This wind direction produces the maximum wind loads on the arrays except at the array edge where oblique winds produce larger edge pressure loads. The arrays located at the outer boundary of an array field have a protective influence on the interior arrays of the field. A significant decrease of the array wind loads were recorded in the wind tunnel test on array panels located behind a fence and/or interior to the array field compared to the arrays on the boundary and unprotected from the wind. The magnitude of this decrease was the same whether caused by a fence or upwind arrays.

  8. Effect of functional fatigue on vertical ground-reaction force in individuals with flat feet.

    Science.gov (United States)

    Boozari, Sahar; Jamshidi, Ali Ashraf; Sanjari, Mohammad Ali; Jafari, Hassan

    2013-08-01

    Flat foot is one of the lower extremity deformities that might change kinetic variables of gait. Fatigue is one of the factors that can alter the vertical ground-reaction force (GRF). The effect of a fatiguing condition on vertical GRF has not been documented in individuals with flat feet. To examine the fatigue effect on vertical GRF in individuals with flat feet compared with a normal group during barefoot walking. Repeated-measure ANOVA for the effects of fatigue on individuals with flat feet and normal feet. Biomechanics laboratory. 17 subjects with flat feet and 17 normal subjects (recruited according to their arch-height ratio). Three vertical GRF measures (F1, the first peak force; F2, minimum force; and F3, the second peak force) were extracted before and after a functional fatigue protocol. No significant interaction between fatigue and group was observed for the 3 vertical GRF measures. For F2, fatigue and group effects were significant (P = .001 and P = .02, respectively). Furthermore, F2 was higher in the flat-feet group than in the normal group; F2 also increased after fatigue. For F3, only a significant fatigue effect was observed (P = .004). F3 decreased after fatigue in both groups. In the flat-feet group, a decrease in the variation of vertical GRF might be due to more flexible foot joints. After fatigue, muscles might lose their ability to control the foot joints and cause higher F2 in the flat-feet group.

  9. Methods for reducing heat losses from flat plate solar collectors: Phase II. Final report, February 1, 1976--August 31, 1977

    Energy Technology Data Exchange (ETDEWEB)

    Hollands, K.G.T.; Raithby, G.D.; Unny, T.E.

    1978-03-01

    Improvements to flat plate solar collectors for heating and cooling of buildings were investigated through two parallel studies. The first study, which deals with the free convective heat loss from V-corrugated absorber plate to a plane glass cover, has shown that, for the same average spacing, the free convective heat loss is greater for a V-corrugated absorber plate than for a plane absorber plate. However, provided the average spacing is large enough, the amount of increase is slight. The second study, which deals with the free convective heat loss in a honeycomb solar collector in which the honeycomb consists of a set of horizontal partitions, or slits, has shown that provided the solar collector is tilted to near vertical, such a honeycomb gives equivalent or superior free convective loss suppression than does a square-celled honeycomb having the same amount of material. Correlation equations for the free convective heat loss are given for both studies.

  10. Unsteady MHD free convective flow past a vertical porous plate ...

    African Journals Online (AJOL)

    An attempt has been made to study the unsteady MHD free convective flow past a vertical porous plate immersed in a porous medium with Hall current, thermal diffusion and heat source. Analytical solution has been found depending on the physical parameters including the Hartmann number M, the Prandtl number Pr, the ...

  11. Sound Radiation of Aerodynamically Excited Flat Plates into Cavities

    Directory of Open Access Journals (Sweden)

    Johannes Osterziel

    2017-10-01

    Full Text Available Flow-induced vibrations and the sound radiation of flexible plate structures of different thickness mounted in a rigid plate are experimentally investigated. Therefore, flow properties and turbulent boundary layer parameters are determined through measurements with a hot-wire anemometer in an aeroacoustic wind tunnel. Furthermore, the excitation of the vibrating plate is examined by laser scanning vibrometry. To describe the sound radiation and the sound transmission of the flexible aluminium plates into cavities, a cuboid-shaped room with adjustable volume and 34 flush-mounted microphones is installed at the non flow-excited side of the aluminium plates. Results showed that the sound field inside the cavity is on the one hand dependent on the flow parameters and the plate thickness and on the other hand on the cavity volume which indirectly influences the level and the distribution of the sound pressure behind the flexible plate through different excited modes.

  12. Analytical Solution of Forced-Convective Boundary-Layer Flow over a Flat Plate

    DEFF Research Database (Denmark)

    Mirgolbabaei, H.; Barari, Amin; Ibsen, Lars Bo

    2010-01-01

    In this letter, the problem of forced convection heat transfer over a horizontal flat plate is investigated by employing the Adomian Decomposition Method (ADM). The series solution of the nonlinear differential equations governing on the problem is developed. Comparison between results obtained a...... and those of numerical solution shows excellent agreement, illustrating the effectiveness of the method. The solution obtained by ADM gives an explicit expression of temperature distribution and velocity distribution over a flat plate....

  13. 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 paper showed buffeting responses similar to a flat plate with the exception of the multi-box girder which performed much better aerodynamically....

  14. Study on application of flat plate structure to high-rise buildings; Flat plate kozo no koso tatemono eno tekiyo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Takata, K.; Tsuda, K.; Eto, H. [Obayashi Corp., Tokyo (Japan)

    1999-01-10

    In this study, an improved flat plate structure was developed by an attempt to shift the critical section (the bending yield position) from the column surface towards the span center by increasing the amount of main reinforcement near the column joint. Performance testing of the improved flat plate structure to clarify its basic properties, it showed that its hysteresis characteristics were superior to those of the conventional type (the amount of main reinforcement is uniform in the direction of the axis of member). Based on the experimental results, the appraisal of hysteresis characteristics and the method of section computing were established as the design methods. These newly established design methods were applied to the existing 26-story high-rise building of RC construction, and a simulation was performed to analyze the effectiveness of the improved flat plate structure. The response results satisfied the design criteria for general high-rise buildings, thus confirming the feasibility of constructing high-rise buildings incorporating the flat plate structure. (author)

  15. Thermal performance optimization of a flat plate solar air heater using genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Varun; Siddhartha [Department of Mechanical Engineering, National Institute of Technology, Hamirpur 177 005 (H.P.) (India)

    2010-05-15

    Thermal performance of solar air heater is low and different techniques are adopted to increase the performance of solar air heaters, such as: fins, artificial roughness etc. In this paper an attempt has been done to optimize the thermal performance of flat plate solar air heater by considering the different system and operating parameters to obtain maximum thermal performance. Thermal performance is obtained for different Reynolds number, emissivity of the plate, tilt angle and number of glass plates by using genetic algorithm. (author)

  16. Turbulent flow over a long flat plate with uniform roughness

    Science.gov (United States)

    Pullin, D. I.; Hutchins, N.; Chung, D.

    2017-08-01

    For turbulent boundary-layer flow under a uniform freestream speed U∞ over a plate of length L , covered with uniform roughness of nominal sand-grain scale ks, the physical behaviors underlying two distinguished limits at large ReL≡U∞L /ν are explored: the fully rough wall flow where ks/L is fixed and the long-plate limit where Rek≡U∞ks/ν is fixed. For the fully rough limit it is shown that not only is the drag coefficient CD independent of ReL but that a universal skin-friction coefficient Cf and normalized boundary-layer thickness δ /ks can be found that depends only on ks/x , where x is the downstream distance. In the long-plate limit, it is shown that the flow becomes asymptotically smooth at huge ReL at a rate that depends on Rek. Comparisons with wind-tunnel and field data are made.

  17. Water entry of a flat elastic plate at high horizontal speed

    OpenAIRE

    Reinhard, M.; Korobkin, A. A.; Cooker, M. J.

    2013-01-01

    The two-dimensional problem of an elastic-plate impact onto an undisturbed surface of water of infinite depth is analysed. The plate is forced to move with a constant horizontal velocity component which is much larger than the vertical velocity component of penetration. The small angle of attack of the plate and its vertical velocity vary in time, and are determined as part of the solution, together with the elastic deflection of the plate and the hydrodynamic loads within the potential flow ...

  18. Proceedings of the Flat-Plate Solar Array Project Research Forum on the Design of Flat-Plate Photovoltaic Arrays for Central Stations

    Science.gov (United States)

    1983-01-01

    The Flat Plate Solar Array Project, focuses on advancing technologies relevant to the design and construction of megawatt level central station systems. Photovoltaic modules and arrays for flat plate central station or other large scale electric power production facilities require the establishment of a technical base that resolves design issues and results in practical and cost effective configurations. Design, qualification and maintenance issues related to central station arrays derived from the engineering and operating experiences of early applications and parallel laboratory reserch activities are investigated. Technical issues are examined from the viewpoint of the utility engineer, architect/engineer and laboratory researcher. Topics on optimum source circuit designs, module insulation design for high system voltages, array safety, structural interface design, measurements, and array operation and maintenance are discussed.

  19. A diagram for defined solar radiation absorbed per unit area of flat plate solar collectors

    Energy Technology Data Exchange (ETDEWEB)

    Tekin, Y.; Altuntop, N. [Erciyes University, Dept. of Mechanical Engineering (Turkey); Cengel, Y.A. [Nevada Reno University, Dept. of Mechanical Engineering, NV (United States); Cengel, Y.A. [Nevada University, Dept. Mechanical Engineering, Reno, NV (United States)

    2000-07-01

    In Erciyes University, the Solar House (28.75 m{sup 2}) is heated from the floor by using flat plate liquid solar collectors. Required solar radiation for heating and heat losses are calculated. In this work, the required calculations for Erciyes Solar House were generalized and required calculation were done to evaluate absorbed solar radiation per unit surface of the flat plate liquid collector. At the end, three generalized diagrams for nine different months are obtained using obtained numerical values. The goal of preparing diagrams is to determine absorbed solar radiation per unit surface area of flat plate liquid collector at any instant at any latitude, In this work, the diagram is explained by means of sample calculations for November. This diagram was prepared to find out absorbed solar radiation per unit area of black surface collector by means obtained equations. With this diagram, all instant solar radiation can be evaluated in 19 steps. (authors)

  20. Design and performance of tubular flat-plate solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Matsushima, T.; Ikeda, D.; Kanagawa, H. [NTT Integrated Information & Energy Systems Labs., Tokyo (Japan)] [and others

    1996-12-31

    With the growing interest in conserving the environmental conditions, much attention is being paid to Solid Oxide Fuel Cell (SOFC), which has high energy-conversion efficiency. Many organizations have conducted studies on tubular and flat type SOFCs. Nippon Telegraph and Telephone Corporation (NTT) has studied a combined tubular flat-plate SOFC, and already presented the I-V characteristics of a single cell. Here, we report the construction of a stack of this SOFC cell and successful generation tests results.

  1. Streamwise counter-rotating vortices generated by triangular leading edge pattern in flat plate boundary layer

    KAUST Repository

    Hasheminejad, S. M.

    2016-01-05

    A series of flow visualizations were conducted to qualitatively study the development of streamwise counter-rotating vortices over a flat plate induced by triangular patterns at the leading edge of a flat plate. The experiments were carried out for a Reynolds number based on the pattern wavelength (λ) of 3080. The results depict the onset, development and breakdown of the vortical structures within the flat plate boundary layer. Moreover, the effect of one spanwise array of holes with diameter of 0.2λ (=3 mm) was examined. This investigation was done on two different flat plates with holes placed at the location x/λ = 2 downstream of the troughs and peaks. The presence of holes after troughs does not show any significant effect on the vortical structures. However, the plate with holes after peaks noticeably delays the vortex breakdown. In this case, the “mushroom-like” vortices move away from the wall and propagate downstream with stable vortical structures. The vortex growth is halted further downstream but start to tilt aside.

  2. Modeling the effect of the inclination angle on natural convection from a flat plate: The case of a photovoltaic module

    Directory of Open Access Journals (Sweden)

    Perović Bojan D.

    2017-01-01

    Full Text Available The main purpose of this paper is to show how the inclination angle affects natural convection from a flat-plate photovoltaic module which is mounted on the ground surface. In order to model this effect, novel correlations for natural convection from isothermal flat plates are developed by using the fundamental dimensionless number. On the basis of the available experimental and numerical results, it is shown that the natural convection correlations correspond well with the existing empirical correlations for vertical, inclined, and horizontal plates. Five additional correlations for the critical Grashof number are derived from the available data, three indicating the onset of transitional flow regime and two indicating the onset of flow separation. The proposed correlations cover the entire range of inclination angles and the entire range of Prandtl numbers. This paper also provides two worked examples, one for natural convection combined with radiation and one for natural convection combined with forced convection and radiation. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR33046

  3. Parametric Studies of Flat Plate Trajectories Using VIC and Penalization

    Directory of Open Access Journals (Sweden)

    François Morency

    2018-01-01

    Full Text Available Flying debris is generated in several situations: when a roof is exposed to a storm, when ice accretes on rotating wind turbines, or during inflight aircraft deicing. Four dimensionless parameters play a role in the motion of flying debris. The goal of the present paper is to investigate the relative importance of four dimensionless parameters: the Reynolds number, the Froude number, the Tachikawa number, and the mass moment of inertia parameters. Flying debris trajectories are computed with a fluid-solid interaction model formulated for an incompressible 2D laminar flow. The rigid moving solid effects are modelled in the Navier-Stokes equations using penalization. A VIC scheme is used to solve the flow equations. The aerodynamic forces and moments are used to compute the acceleration and the velocity of the solid. A database of 64 trajectories is built using a two-level full factorial design for the four factors. The dispersion of the plate position at a given horizontal position decreases with the Froude number. Moreover, the Tachikawa number has a significant effect on the median plate position.

  4. COMPARATIVE FIELD EXPERIMENTAL INVESTIGATIONS OF DIFFERENT FLAT PLATE SOLAR COLLECTORS

    Directory of Open Access Journals (Sweden)

    Guangming Chen

    2015-12-01

    Full Text Available Full-scale traditional metal solar collectors and solar collector specimens fabricated from polymeric materials were investigated in the present study. A polymeric collector is 67.8% lighter than a traditional metal solar collector, and a metal solar collector with transparent plastic covering is 40.3% lighter than a traditional metal solar collector. Honeycomb multichannel plates made from polycarbonate were chosen to create a polymeric solar collector. A test rig for the natural circulation of the working fluid in a solar collector was built for a comparative experimental investigation of various solar collectors operating at ambient conditions. It was shown experimentally that the efficiency of a polymeric collector is 8–15% lower than the efficiency of a traditional collector.

  5. Simulations of the transient flow generated from a started flat plate

    Science.gov (United States)

    Wang, Leqin; Ma, Xudan; Li, Zhifeng; Wu, Peng; Wu, Dazhuan

    2012-11-01

    Transient operations are commonly founded in fluid machineries such as the starting, stopping, and variations of rotor speeds, etc. Flow generated from a started flat plate is of fundamental importance. Experiments have been done to observe the flow evolution in current researches. And in order to explore the flow in more detailed scale, some vortex methods with high resolution and other numerical methods were developed to solve various related problems by some researchers. But the promotion of vortex method to engineering application is rare due to its complexity and difficulty in specifying the boundary conditions. In order to build up a method of numerical study for such problems, a simplified model is built up with a flat plate. The development of two-dimensional viscous incompressible flow generated from an impulsively started and uniformly accelerated infinitesimally thin flat plate is simulated numerically. A dynamic mesh(DM) method based on the spring analogue and local remeshing is applied to realize the mesh motion caused by the started plate. Researches show that the mesh quality will decline under large grid shear force during the updating process. To conquer this problem, a region near the plate is separated to guarantee the mesh quality at location of interest which is the innovation of the present paper. All computations at least cover a period during which the plate translates 6 times its length. The simulated instantaneous velocity profiles, flow structures and drag coefficients under several Reynolds numbers (20⩽ Re⩽126) and accelerations (20 m/s2⩽ a⩽152 m/s2) are presented and compared with existing results in literatures. Comparisons are found to be satisfactory, confirming the validity of the current proposed method(region separated DM). The proposed DM method is firstly used to study the transient flow generated from a started flat plate and can be used in further study of transient characteristics during transient operations of turbo

  6. Evaluation of the flat-plate solar collector system for electric power generation

    Science.gov (United States)

    Athey, R. E.

    1976-01-01

    This evaluation of the flat-plate collector system was designed to determine the number of flat-plate collectors required to generate a given amount of electricity with optimum efficiency. Variable parameters are the temperature of the heat-transport fluid, both to and from the collector field. In the analysis, the efficiency of the flat-plate collectors was coupled to the efficiency of the thermal cycle to calculate optimal overall system efficiencies. Overall system efficiencies for the system are on the order of 3.5 per cent or less. Over two million 4 ft-by-4 ft collectors would be required to produce 100,000 kW(e). Based on the results, it can be shown that the limiting factor in the use of the flat-plate collector system for electric power generation is the efficiency of the collectors. An increase in the overall system efficiency can occur only if the collector efficiency can be increased at higher surface temperatures.

  7. An investigation on thermo-hydraulic performance of a flat-plate channel with pyramidal protrusions

    NARCIS (Netherlands)

    Ebrahimi, Amin; Naranjani, Benyamin

    2016-01-01

    In this study, a flat-plate channel configured with pyramidal protrusions are numerically analysed for the first time. Simulations of laminar single-phase fluid flow and heat transfer characteristics are developed using a finite-volume approach under steady-state condition. Pure water is selected

  8. A grooved glass surface-plate for making a flat polished surface

    Science.gov (United States)

    Miyagi, Isoji

    2017-01-01

    To obtain a flat polished surface for microchemical analyses such as EPMA, SIMS, and ATR micro-FTIR, a glass plate with a grooved surface was developed for hand polishing with an abrasive film. It eases the polishing process by minimizing slipping or sticking, and results in negligible relief in the sample surface.

  9. Design and installation package for the Sunmat Flat Plate Solar Collector

    Energy Technology Data Exchange (ETDEWEB)

    1978-03-01

    The information used in evaluating the design of the Sunmat Liquid Flat Plat Plate Solar Collector developed by Calmac Manufacturing Company is presented. Included in this package are the Subsystem Performance Specification, Installation, Operation and Maintenance Manuals, collector sizing guides, and detailed drawings of the single-glazed collector.

  10. Preliminary design review package on air flat plate collector for solar heating and cooling system

    Science.gov (United States)

    1977-01-01

    Guidelines to be used in the development and fabrication of a prototype air flat plate collector subsystem containing 320 square feet (10-4 ft x 8 ft panels) of collector area are presented. Topics discussed include: (1) verification plan; (2) thermal analysis; (3) safety hazard analysis; (4) drawing list; (5) special handling, installation and maintenance tools; (6) structural analysis; and (7) selected drawings.

  11. A figure of merit for selective absorbers in flat plate solar water heaters

    CSIR Research Space (South Africa)

    Roberts, DE

    2013-12-01

    Full Text Available We derive from first principles an analytical expression for a figure of merit (FM) for a selective solar absorber in a single glazed flat plate water heater. We first show that the efficiency of a collector with an absorber with absorptance α...

  12. Flat Plate Solar Array Project: Proceedings of the 20th Project Integration Meeting

    Science.gov (United States)

    Mcdonald, R. R.

    1982-01-01

    Progress made by the Flat-Plate Solar Array Project during the period November 1981 to April 1982 is reported. Project analysis and integration, technology research in silicon material, large-area silicon sheet and environmental isolation, cell and module formation, engineering sciences, and module performance and failure analysis are covered.

  13. A Didactic Experiment and Model of a Flat-Plate Solar Collector

    Science.gov (United States)

    Gallitto, Aurelio Agliolo; Fiordilino, Emilio

    2011-01-01

    We report on an experiment performed with a home-made flat-plate solar collector, carried out together with high-school students. To explain the experimental results, we propose a model that describes the heating process of the solar collector. The model accounts quantitatively for the experimental data. We suggest that solar-energy topics should…

  14. Production of fatty acids and protein by nannochloropsis in flat-plate photobioreactors

    NARCIS (Netherlands)

    Hulatt, Chris J.; Wijffels, René H.; Bolla, Sylvie; Kiron, Viswanath

    2017-01-01

    Nannochloropsis is an industrially-promising microalga that may be cultivated for alternative sources of nutrition due to its high productivity, protein content and lipid composition. We studied the growth and biochemical profile of Nannochloropsis 211/78 (CCAP) in optimized flat-plate

  15. Internal (Annular) and Compressible External (Flat Plate) Turbulent Flow Heat Transfer Correlations.

    Energy Technology Data Exchange (ETDEWEB)

    Dechant, Lawrence [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Smith, Justin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    Here we provide a discussion regarding the applicability of a family of traditional heat transfer correlation based models for several (unit level) heat transfer problems associated with flight heat transfer estimates and internal flow heat transfer associated with an experimental simulation design (Dobranich 2014). Variability between semi-empirical free-flight models suggests relative differences for heat transfer coefficients on the order of 10%, while the internal annular flow behavior is larger with differences on the order of 20%. We emphasize that these expressions are strictly valid only for the geometries they have been derived for e.g. the fully developed annular flow or simple external flow problems. Though, the application of flat plate skin friction estimate to cylindrical bodies is a traditional procedure to estimate skin friction and heat transfer, an over-prediction bias is often observed using these approximations for missile type bodies. As a correction for this over-estimate trend, we discuss a simple scaling reduction factor for flat plate turbulent skin friction and heat transfer solutions (correlations) applied to blunt bodies of revolution at zero angle of attack. The method estimates the ratio between axisymmetric and 2-d stagnation point heat transfer skin friction and Stanton number solution expressions for sub-turbulent Reynolds numbers %3C1x10 4 . This factor is assumed to also directly influence the flat plate results applied to the cylindrical portion of the flow and the flat plate correlations are modified by

  16. Accuracy of Surface Plate Measurements - General Purpose Software for Flatness Measurement

    NARCIS (Netherlands)

    Meijer, J.; Heuvelman, C.J.

    1990-01-01

    Flatness departures of surface plates are generally obtained from straightness measurements of lines on the surface. A computer program has been developed for on-line measurement and evaluation, based on the simultaneous coupling of measurements in all grid points. Statistical methods are used to

  17. The effect of blowing or suction on laminar free convective heat transfer on flat horizontal plates

    NARCIS (Netherlands)

    Brouwers, Jos

    1993-01-01

    In the present paper laminar free convective heat transfer on flat permeable horizontal plates is investigated. To assess the effect of surface suction or injection on heat transfer a correction factor, provided by the film model (or ldquofilm theoryrdquo), is applied. Comparing the film model

  18. Design, construction and testing of a low-cost flat plate solar energy ...

    African Journals Online (AJOL)

    A low-cost flat plate solar energy collector has been designed and constructed with locally available materials such as mild steel and black paint of absorptance 0.94. On testing, an average daily efficiency of 55.6% was obtained. The methods are simple and illustrate the fact that construction of efficient collectors are ...

  19. Five to ten MA experiments using flat plate explosive generators

    Energy Technology Data Exchange (ETDEWEB)

    Caird, R. S.; Fowler, C. M.; King, J. C. (James Carrel); Oona, H. (Henn); Tasker, D. G. (Douglas G.); Goforth, J. H. (James H.)

    2001-01-01

    High explosive pulsed power (HEPP) techniques can address a wide range of pulsed power needs. The basis for HEPP techniques is the use of high explosives to reduce the inductance of a current-carrying circuit, thus multiplying the current due to magnetic flux conservation. For the past twenty years at Los Alamos, our high energy density physics (HEDP) program has followed a path leading to more sophisticated and higher current (and often power) systems. Twenty years ago, we had the capability of conducting tests at 10, or even 30 MA, with no power conditioning and low inductance loads. The time scale of the experiment was the time it took to compress the flux explosively, and our fastest generator with high current capability was a plate generator. The operating time of the generator is less than 15 {micro}s, and flux loading requires either an additional {approx}60 {micro}s or a reduced-efficiency inductive coupling scheme. We could also deliver shortened pulses to select loads by completing our generator circuit, initially, with a relatively high inductance circuit element, then switching in a lower inductance with 2-3 {micro}s left of the generator pulse. Figure 1 shows the results of such a test. The test was conducted in 1974 to investigate our capability to drive plasma z-pinch experiments for the production of soft x-rays, and was a pulsed power success. However, our understanding of vacuum power flow issues was not mature enough at that time to design a functioning plasma z-pinch load. There was a renewed need for such a system in 1980, and at that time we began assembling a complete set of techniques required for success. We first fielded a baseline test using a simplified version of the HEPP system that generated the Figure 1 data. Subsequent tests followed a 'bite size' philosophy. That is, we first designed a complete system for a level of complexity at which we believed success could be achieved. We conducted tests of that system, and once it

  20. Pressure pulsations on a flat plate normal to an underexpanded supersonic jet

    Science.gov (United States)

    Back, L. H.; Sarohia, V.

    1978-01-01

    An experiment was devised to study the interaction between an underexpanded supersonic gas jet and a flat plate, with the plate located in a region in which the interaction produces shock wave and flow fluctuations. Nitrogen gas at ambient stagnation temperature flowed through a convergent nozzle with exit diameter of 2.03 cm and impinged on a square metal plate normal to the jet. Results revealed local peak pressure fluctuations on the plate at nozzle pressure ratios of about 2 and 4.5, with the latter case producing fluctuations of the same order as the mean pressure on the plate; the frequency of the oscillations was as large as 20 kHz. For choked jet flow at ambient pressure higher than atmospheric, the pressure fluctuations would increase accordingly, and adjacent solid structures would therefore be subjected to proportionately higher normal stresses.

  1. Compressibility effects on flat-plates with serrated leading-edges at a low Reynolds number

    Science.gov (United States)

    Mangeol, Étienne; Ishiwaki, Daichi; Wallisky, Nicolas; Asai, Keisuke; Nonomura, Taku

    2017-11-01

    This study evaluates the influence of a serrated leading edge on flat-plate aerodynamics at low-Reynolds-number and subsonic high-Mach-number conditions. Forces are measured for a Mach number ranging from 0.2 to 0.64 at a Reynolds number of (12,000 ± 1000). Pressure distributions are obtained under the same conditions using pressure sensitive paint (PSP) measurement. Three models are tested: a flat plate without serrations used as the baseline case and two flat plates with serrated leading edges of different wavelength-to-amplitude ratios. Results show that the aerodynamic performance of flat plates with serrations is slightly changed from the baseline case. The plate with short-wavelength serrations underperforms in terms of the lift-to-drag ratio under all the conditions compared to the baseline case while the plate with large-wavelength serrations slightly outperforms it at around the stall angle. The Mach number has little effect on the attached flow while the lift increases with the Mach number under deep stall conditions. Serrations maintain the lift even under high angle of attack conditions when Mach number varies. The two-dimensional pressure distributions and the analyses of local chordwise pressure coefficient distributions at different spanwise locations and of periodicity of spanwise pressure coefficients allow categorisation of the complex flow structures into three types. These configurations feature different types of low pressure regions downstream of troughs. The periodicity of the pattern depends not only on the angle of attack but also on the Mach number.

  2. Experimental study on productivity of modified single-basin solar still with a flat plate absorber

    Science.gov (United States)

    Ramanathan, V.; Kanimozhi, B.; Bhojwani, V. K.

    2017-05-01

    Solar still is an apparatus which uses solar energyto producedistilled water from saline water. This can be used in remote areas effectively wherein electricity is not available. The output from a conventional single basin solar still is found to be very low. Hence research is required to increase the productivity of the conventional solar still. This work is an attempt to increase the productivity of solar still. A flat mica plate is embedded in the conventional solar still to augment evaporation of the water from the input saline water. The flat plate absorber is placed in such a way that it is parallel to the glass cover of the solar still so as to maximize the absorption of solar radiations. By this modification, the maximum temperature of the absorber plate achieved was 95°C in comparison to 67°C of the conventional solar still. Experimental results of modified solar still were compared with conventional solar still. It was found that distillate output increased by 25% with a flat plate absorber when compared to conventional still.

  3. Experimental investigation of effects of jet decay rate on jet-induced pressures on a flat plate: Tabulated data

    Science.gov (United States)

    Kuhlman, J. M.; Ousterhout, D. S.; Warcup, R. W.

    1978-01-01

    Tabular data are presented for an experimental study of the effects of jet decay rate on the jet-induced pressure distribution on a flat plate for a single jet issuing at right angle to the flat plate into a uniform crossflow. The data are presented in four sections: (1) presents the static nozzle calibration data; (2) lists the plate surface static pressure data and integrated loads; (3) lists the jet centerline trajectory data; and (4) lists the centerline dynamic pressure data.

  4. Proceedings of the Flat-Plate Solar Array Project Research Forum on the design of flat-plate photovoltaic arrays for central stations

    Energy Technology Data Exchange (ETDEWEB)

    None

    1983-01-01

    The Flat-Plate Solar Array Project, managed by the Jet Propulsion Laboratory for the US Department of Energy, has focused on advancing technologies relevant to the design and construction of megawatt-level central-station systems. Photovoltaic modules and arrays for flat-plate central-station or other large-scale electric power production facilities require the establishment of a technical base that resolves design issues and results in practical and cost-effective configurations. The Central Station Research Forum addressed design, qualification and maintenance issues related to central-station arrays derived from the engineering and operating experiences of early applications and parallel laboratory research activities. Technical issues were examined from the viewpoint of the utility engineer, architect-engineer and laboratory researcher. The forum included presentations on optimum source-circuit designs, module insulation design for high system voltages, array safety, structural interface design, measurements and array operation and maintenance. The Research Forum focused on current capabilities as well as design difficulties requiring additional technological thrusts and/or continued research emphasis. Session topic summaries highlighting major points during group discussions, identifying promising technical approaches or areas of future research, are presented.

  5. Deflection and trapping of a counter-rotating vortex pair by a flat plate

    Science.gov (United States)

    Nitsche, Monika

    2017-12-01

    The interaction of a counter-rotating vortex pair (dipole) with a flat plate in its path is studied numerically. The vortices are initially separated by a distance D (dipole size) and placed far upstream of a plate of length L . The plate is centered on the dipole path and inclined relative to it at an incident angle βi. At first, the plate is held fixed in place. The vortices approach the plate, travel around it, and then leave as a dipole with unchanged velocity but generally a different travel direction, measured by a transmitted angle βt. For certain plate angles the transmitted angle is highly sensitive to changes in the incident angle. The sensitivity increases as the dipole size decreases relative to the plate length. In fact, for sufficiently small values of D /L , singularities appear: near critical values of βi, the dipole trajectory undergoes a topological discontinuity under changes of βi or D /L . The discontinuity is characterized by a jump in the winding number of one vortex around the plate, and in the time that the vortices take to leave the plate. The jumps occur repeatedly in a self-similar, fractal fashion, within a region near the critical values of βi, showing the existence of incident angles that trap the vortices, which never leave the plate. The number of these trapping regions increases as the parameter D /L decreases, and the dependence of the motion on βi becomes increasingly complex. The simulations thus show that even in this apparently simple scenario, the inviscid dynamics of a two-point-vortex system interacting with a stationary wall is surprisingly rich. The results are then applied to separate an incoming stream of dipoles by an oscillating plate.

  6. Investigation of Shear Stud Performance in Flat Plate Using Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    T.S. Viswanathan

    2014-09-01

    Full Text Available Three types of shear stud arrangement, respectively featuring an orthogonal, a radial and a critical perimeter pattern, were evaluated numerically. A numerical investigation was conducted using the finite element software ABAQUS to evaluate their ability to resist punching shear in a flat plate. The finite element analysis here is an application of the nonlinear analysis of reinforced concrete structures using three-dimensional solid finite elements. The nonlinear characteristics of concrete were achieved by employing the concrete damaged plasticity model in the finite element program. Transverse shear stress was evaluated using finite element analysis in terms of shear stress distribution for flat plate with and without shear stud reinforcement. The model predicted that shear studs placed along the critical perimeter are more effective compared to orthogonal and radial patterns.

  7. Accurate stratospheric particle size distributions from a flat plate collection surface

    Science.gov (United States)

    Zolensky, M. E.; Mackinnon, I. D. R.

    1985-01-01

    Flat plate particle collections have revealed the presence of a remarkable variety of both terrestrial and extraterrestrial material in the stratosphere. It is found that the ratio of terrestrial to extraterrestrial material and the nature of the material collected may vary significantly over short time scales. These fluctuations may be related to massive injections of volcanic ash, emissions from solid fuel rockets, or variations in the micrometeoroid flux. The variations in particle number density can be of great importance to the earth's atmospheric radiation balance, and, therefore, its climate. With the objective to assess the number density of solid particles in the stratosphere, an examination has been conducted of all particles exceeding 1 micron in average diameter for a representative suite of particles obtained from a single flat plate collection surface. Attention is given to solid particle size distributions in the stratosphere, and the origin of important stratospheric particle types.

  8. Flat plate vs. concentrator solar photovoltaic cells - A manufacturing cost analysis

    Science.gov (United States)

    Granon, L. A.; Coleman, M. G.

    1980-01-01

    The choice of which photovoltaic system (flat plate or concentrator) to use for utilizing solar cells to generate electricity depends mainly on the cost. A detailed, comparative manufacturing cost analysis of the two types of systems is presented. Several common assumptions, i.e., cell thickness, interest rate, power rate, factory production life, polysilicon cost, and direct labor rate are utilized in this analysis. Process sequences, cost variables, and sensitivity analyses have been studied, and results of the latter show that the most important parameters which determine manufacturing costs are concentration ratio, manufacturing volume, and cell efficiency. The total cost per watt of the flat plate solar cell is $1.45, and that of the concentrator solar cell is $1.85, the higher cost being due to the increased process complexity and material costs.

  9. Recommendations for the performance rating of flat plate terrestrial photovoltaic solar panels

    Science.gov (United States)

    Treble, F. C.

    1976-01-01

    A review of recommendations for standardizing the performance rating of flat plate terrestrial solar panels is given to develop an international standard code of practice for performance rating. Required data to characterize the performance of a solar panel are listed. Other items discussed are: (1) basic measurement procedures; (2) performance measurement in natural sunlight and simulated sunlight; (3) standard solar cells; (4) the normal incidence method; (5) global method and (6) definition of peak power.

  10. Guidelines for Gridding Simple Flows - The Flat Plate in Laminar Flow

    Science.gov (United States)

    2008-01-01

    a practical level is the uncertainty of creating an initial grid that will produce a sufficiently accurate solution for the problem at hand...established, classical analysis provides very accurate flow data against which to test and tweak any proposed rules of thumb. 11. METHODOLOGY A...is to quantify the expected level of accuracy apriori for simple, incompressible, flat plate flow grids. The approach then is to first select a

  11. Experimental testing of various heat transfer structures in a flat plate thermal energy storage unit

    OpenAIRE

    Johnson, Maike; Fiss, Michael; Klemm, Torsten

    2016-01-01

    For solar process heat applications with steam as the working fluid and varying application parameters, a novel latent heat storage concept has been developed using an adaptation of a flat plate heat exchanger as the storage concept. Since the pressure level in these applications usually does not exceed 30 bar, an adaptation with storage material chambers arranged between heat transfer medium chambers is possible. Phase change materials are used as the storage medium, so that the isotherma...

  12. Flat-plate collector performance evaluation. The case for a solar simulation approach

    Science.gov (United States)

    Simon, F. F.; Harlamert, P.

    1973-01-01

    A method is proposed for determining the performance of flat-plate solar collector using a simulated sun. Collector test variables that will help establish the basis for the indoor test facility at the Lewis Research Center are discussed. The use of the indoor testing should permit a standard test for the convenient and accurate determination of collector performance. Preliminary test results are reported as an example of the type of collector performance data to be expected from the simulation approach.

  13. Development of flat-plate solar collectors for the heating and cooling of buildings: Executive summary

    Science.gov (United States)

    1978-01-01

    An efficient, low cost, flat-plate solar collector was developed. Computer aided mathematical models of the heat process in the collector were used in defining absorber panel configuration; determining insulation thickness; and in selecting the number, spacing, and material of the covers. Prototypes were built and performance tested. Data from simulated operation of the collector are compared with predicted loads from a number of locations to determine the degree of solar utilization.

  14. Proceedings of the flat-plate solar array project research forum on photovoltaic metallization systems

    Energy Technology Data Exchange (ETDEWEB)

    None

    1983-11-15

    A Photovoltaic Metallization Research Forum, under the sponsorship of the Jet Propulsion Laboratory's Flat-Plate Solar Array Project and the US Department of Energy, was held March 16-18, 1983 at Pine Mountain, Georgia. The Forum consisted of five sessions, covering (1) the current status of metallization systems, (2) system design, (3) thick-film metallization, (4) advanced techniques and (5) future metallization challenges. Twenty-three papers were presented.

  15. The pressure field of a gust interacting with a flat plate

    Science.gov (United States)

    Atassi, Hafiz M.; Patrick, Sheryl M.

    1995-01-01

    A semianalytical solution is presented for the unsteady pressure field of a vortical gust interacting with a flat-plate airfoil in subsonic flow. The solution will serve as a benchmark for evaluating the accuracy and efficiency of time dependent numerical schemes. The specific case considered corresponds to the ICASE benchmark problem number 6. The results are compared with those of asymptotic theories for high frequency and show excellent agreement.

  16. Monitoring of a flat plate solar thermal field supplying process heat

    OpenAIRE

    Cozzini Marco; Fedrizzi Roberto; Pipiciello Mauro; Söll Robert; Ben Hassine Ilyes; Pietruschka Dirk

    2016-01-01

    The article reports the performance data of a flat plate collector field installed in Austria and supplying process heat to a meat factory, up to a temperature of about 95 °C. The presented data span an entire year, thereby including seasonal effects and allowing for a full characterization of the system performances. Sensor uncertainty is also discussed in detail. Finally, a bin method analysis of the field efficiency is provided. To this purpose, different operating conditions are concisely...

  17. Development of electromagnetic welding facility of flat plates for nuclear industry

    Science.gov (United States)

    Kumar, Rajesh; Sahoo, Subhanarayan; Sarkar, Biswanath; Shyam, Anurag

    2017-04-01

    Electromagnetic pulse welding (EMPW) process, one of high speed welding process uses electromagnetic force from discharged current through working coil, which develops a repulsive force between the induced current flowing parallel and in opposite direction. For achieving the successful weldment using this process the design of working coil is the most important factor due to high magnetic field on surface of work piece. In case of high quality flat plate welding factors such as impact velocity, angle of impact standoff distance, thickness of flyer and overlap length have to be chosen carefully. EMPW has wide applications in nuclear industry, automotive industry, aerospace, electrical industries. However formability and weldability still remain major issues. Due to ease in controlling the magnetic field enveloped inside tubes, the EMPW has been widely used for tube welding. In case of flat components control of magnetic field is difficult. Hence the application of EMPW gets restricted. The present work attempts to make a novel contribution by investigating the effect of process parameters on welding quality of flat plates. The work emphasizes the approaches and engineering calculations required to effectively use of actuator in EMPW of flat components.

  18. Vertical Electric Field Measurements with Copper Plates by Sounding Balloon

    Science.gov (United States)

    Wen, Shao-Chun; Chiu, Cheng-Hsiu; Bing-Chih Chen, Alfred; Hsu, Rue-Ron; Su, Han-Tzong

    2015-04-01

    The vertical electric field plays an important role in driving the circulation of the global electric circuit, and crucial to the formation of the transient luminous events (TLEs). The in-situ measurement of the electric field in the upper atmosphere, especially from cloud top to the bottom of the ionosphere is very challenging but essential. Limited by the flight vehicle, the measurements of the electric field in and above cloud, especiall thundercloud, is rare up to now. A light-weight electric field meter was developed independently and sent to 30 km height by small meteorological balloons successfully. Other than the existing long-spaced, spherical probe design, an improved electric field meter has been built and tested carefully. A new circuit with ultra high input impedance and a high voltage amplifier is implemented to reduce the AC noise induced by the voltage divider. Two copper plates are used to replace the double spherical probes which is spaced by a long fiberglass boom. The in-lab calibration and tests show that this new model is superior to the existing design and very sensitive to the variation of the DC electric field. In this poster, the design and the in-lab tests will be presented, and preliminary results of the flight experiments are also discussed.

  19. On Nonperturbative Techniques for Thermal Radiation Effect on Natural Convection past a Vertical Plate Embedded in a Saturated Porous Medium

    Directory of Open Access Journals (Sweden)

    R. J. Moitsheki

    2008-10-01

    Full Text Available In this article, the heat transfer characteristics of natural convection about a vertical permeable flat surface embedded in a saturated porous medium are studied by taking into account the thermal radiation effect. The plate is assumed to have a power-law temperature distribution. Similarity variables are employed in order to transform the governing partial differential equations into a nonlinear ordinary differential equation. Both Adomian decomposition method (ADM and He's variational iteration method (VIM coupled with Padé approximation technique are implemented to solve the reduced system. Comparisons with previously published works are performed, and excellent agreement between the results is obtained.

  20. Simulation and Experimental Investigation of Thermal Performance of a Miniature Flat Plate Heat Pipe

    Directory of Open Access Journals (Sweden)

    R. Boukhanouf

    2013-01-01

    Full Text Available This paper presents the results of a CFD analysis and experimental tests of two identical miniature flat plate heat pipes (FPHP using sintered and screen mesh wicks and a comparative analysis and measurement of two solid copper base plates 1 mm and 3 mm thick. It was shown that the design of the miniature FPHP with sintered wick would achieve the specific temperature gradients threshold for heat dissipation rates of up to 80 W. The experimental results also revealed that for localised heat sources of up to 40 W, a solid copper base plate 3 mm thick would have comparable heat transfer performances to that of the sintered wick FPHP. In addition, a marginal effect on the thermal performance of the sintered wick FPHP was recorded when its orientation was held at 0°, 90°, and 180° and for heat dissipation rates ranging from 0 to 100 W.

  1. Wakefields of a Beam near a Single Plate in a Flat Dechirper

    Energy Technology Data Exchange (ETDEWEB)

    Bane, Karl [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stupakov, Gennady [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2016-11-29

    At linac-based, X-ray free electron lasers (FELs), there is interest in streaking the beam by inducing the transverse wakes in a flat dechirper, by passing the beam near to one of its two jaws. For LCLS-II - as has already been done for LCLS-I - this way of using the dechirper will e.g. facilitate two-color and fresh slice schemes of running the FEL. With the beam a distance from the near wall of say b ~ 0.25 mm and from the far wall by ≳ 5 mm, the second wall will no longer affect the results. The physics will be quite different from the two plate case: with two plates the impedance has a resonance spike whose frequency depends on the plate separation 2a; in the single plate case this parameter no longer exists. Formulas for the longitudinal, dipole, and quadrupole wakes for a beam off-axis between two dechirper plates, valid for the range of bunch lengths of interest in an X-ray FEL, are given in reference 3. By taking the proper limit, we can obtain the corresponding wakes for a beam close to one dechirper plate and far from the other. This is the task we perform in this note.

  2. Comparing wake structures behind a finite aspect ratio and an infinite span normal thin flat plate

    Science.gov (United States)

    Hemmati, Arman; Wood, David H.; Martinuzzi, Robert J.

    2014-11-01

    The wake of an infinite span (2D) thin flat plate and that of a finite aspect ratio, AR = 3.2, plate, both normal to a uniform stream, are compared using DNS at Re = 1200. For the 2D plate, three wake flow regimes are observed. Intervals of typical anti-symmetric Karman shedding (Regime M) are interrupted by intervals where the shear layer folding process first delayed (Regime L) and then accelerated, Regime H. The distinct flow patterns in these regimes have significant impact on lift and drag values, wake structure and instantaneous pressure loads. In contrast, only Regime M is observed for the AR = 3.2 plate. The presence of two lateral shear layers appears to maintain the Karman shedding. Compared to the infinite plate: the mean recirculation region shrinks by 45 % to 1.57H; the magnitude of the Reynolds Stresses drops significantly; Turbulent kinetic energy levels along the wake centerline and peak production and dissipation rates are significantly lower. Further, the three normal Reynolds stresses are comparable in magnitude. To better understand the impact of additional shear layers on the wake stability and resultant wake structures, the 3D structures will be reconstructed using DNS results. Pressure and stress distribution along the plate surfaces will also be examined. This work is supported by AITF and NSERC fellowship grants.

  3. Heat transfer in flow past a continuously moving semi-infinite flat plate in transverse magnetic field with heat flux

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, T.V.R.

    Thermal boundary layer on a continuously moving semi-infinite flat plate in the presence of transverse magnetic field with heat flux has been examined. Similarity solutions have been derived and the resulting equations are integrated numerically...

  4. Experimental investigation of jet-induced loads on a flat plate in hover out-of-ground effect

    Science.gov (United States)

    Kuhlman, J. M.; Warcup, R. W.

    1979-01-01

    Effects of varying jet decay rate on jet-induced loads on a flat plate located in the plane of the jet exit perpendicular to the jet axis were investigated using a small-scale laboratory facility. Jet decay rate has been varied through use of two cylindrical centerbodies having either a flat or hemispherical tip, which were submerged various distances below the flat plate jet exit plane. Increased jet decay rate, caused by the presence of a center-body or plug in the jet nozzle, led to an increased jet-induced lift loss on the flat plate. Jet-induced lift losses reached 1 percent of the jet thrust for the quickest jet decay rates for plate areas equal to 100 times the effective jet exit area. The observed lift loss versus jet decay rate trend agreed well with results of previous investigations.

  5. An Analysis of CFD and Flat Plate Predictions of Friction Drag for the TCA W/B at Supersonic Cruise

    Science.gov (United States)

    Lawrence, Scott L.

    1999-01-01

    This paper presents results of a study which attempted to provide some understanding of the relationship between skin friction drag estimates produced by flat plate methods and those produced by Navier-Stokes computations. A brief introduction is followed by analysis, including a flat plate grid study, analysis of the wing flow, an analysis of the fuselage flow. Other results of interest are then presented, including turbulence model sensitivities, and brief analysis of other configurations.

  6. Improved Thermal-Vacuum Compatible Flat Plate Radiometric Souce for System-Level Testing of Optical Sensors

    Science.gov (United States)

    Schwarz, Mark A.; Kent, Craig J.; Bousquet, Robert; Brown, Steven W.

    2015-01-01

    This work describes the development of an improved vacuum compatible flat plate radiometric source used for characterizing and calibrating remote optical sensors, in situ, throughout their testing period. The original flat plate radiometric source was developed for use by the VIIRS instrument during the NPOESS Preparatory Project (NPP). Following this effort, the FPI has had significant upgrades in order to improve both the radiometric throughput and uniformity. Results of the VIIRS testing with the reconfigured FPI are reported and discussed.

  7. An investigation into the tripping behavior of longitudinally T-stiffened rectangular flat plates loaded statically and impulsively

    OpenAIRE

    Budweg, Howard L.

    1986-01-01

    Approved for public release; distribution unlimited An experimental investigation was conducted to determine the static and dynamic responses of a specific stiffened flat plate design. The air-backed rectangular flat plates of 6061-T6 aluminum with an externally machined longitudinal narrow- flanged T- stiffener and clamped boundary conditions were subjected to static loading by water hydropump pressure and shock loading from an eight pound TNT charge detonated underwa...

  8. Performance Analysis of a Self-Propelling Flat Plate Fin with Joint Compliance

    Science.gov (United States)

    Reddy, N. Srinivasa; Sen, Soumen; Pal, Sumit; Shome, Sankar Nath

    2017-12-01

    Fish fin muscles are compliant and they regulate the stiffness to suit different swimming conditions. This article attempts to understand the significance of presence of compliance in fin muscle with help of a flexible joint flat plate fin model. Blade element method is employed to model hydrodynamics and to compute the forces of interaction during motion of the plate within fluid. The dynamic model of self-propelling fin is developed through multi-body dynamics approach considering the hydrodynamic forces as external forces acting on the fin. The derived hydrodynamic model is validated with experiments on rigid flat plate fin. The effect of the joint stiffness and flapping frequency on the propulsion speed and efficiency is investigated through simulations using the derived and validated model. The propulsion efficiency is found to be highly influenced by the joint stiffness at a given flapping frequency. The fin attained maximum propulsion efficiency when the joint stiffness is tuned to a value at which flapping frequency matches near natural frequency of the fin. At this tuned joint stiffness and flapping frequency, the resulted Strouhal numbers are observed to fall within the optimum range (0.2 to 0.4) for maximized propulsion efficiency of flying birds and swimming aquatic animals reported in literature.

  9. Prediction of vortex-shedding noise from the blunt trailing edge of a flat plate

    Science.gov (United States)

    Wu, Long; Jing, Xiaodong; Sun, Xiaofeng

    2017-11-01

    A time-domain hybrid approach for aerodynamic noise prediction is developed based on a discrete vortex model (DVM) for the unsteady incompressible flow simulation and the acoustic perturbation equations (APE) for the acoustical field computation. The aim is to assess the applicability of the present DVM-APE method to the problems where sound is generated by the large-scale coherent flow structures. The hybrid DVM-APE approach is employed to predict the vortex-shedding noise from the blunt trailing edge of a flat plate. Simulations are implemented on flat plates with different thicknesses in a certain range of low Mach numbers, in order to identify the scaling dependence of the vortex-shedding noise on the freestream speed as well as the plate thickness. Acoustical directivity patterns at different Helmholtz numbers are presented, and agreements are achieved when compared with previous studies. A comparison of the sound pressure level spectrum between the present DVM-APE simulation and the published experimental results is also presented, showing good agreements for both the peak frequencies and the sound pressure levels.

  10. Experimental analysis of the evaporation of sugar cane juice by film on a flat plate

    Directory of Open Access Journals (Sweden)

    Oscar Andrés Mendieta Menjura

    2013-07-01

    Full Text Available In the production of “panela”(a block of unrefined whole cane sugar also known as piloncillo, raspadura, chancaca, jaggery in Colombia, pans that have been traditionally used for evaporation of sugarcane juice have low energ y efficiency problems. In the present study, a flat plate film evaporator was evaluated at a pilot scale. The temperature of the juice and the plate was measured with thermocouples, and the concentration of the soluble solids of the juice was measured with a refractometer. Evaporator performance was determined through the heat transfer coefficient on the side of liquid (h, which was related to the following operating parameters: mass flow, surface temperature, and the temperature and concentration of the fed liquid. The coefficient h profited by increasing : surface temperature (from 140.8 to 181.2 °C, feed concentration (from 18 to 30 °Brix, and juice feed flow (from 5.7 to 38.4 kg/h, and by decreasing feed temperature (from 90 to 60 °C. In the evaporation of sugarcane juice in a flat plate evaporator, h values between 140 and 380 W/m2K were found, which show a marked improvement for evaporation process of sugarcane juice

  11. Effect of Parametric Uncertainties, Variations, and Tolerances on Thermohydraulic Performance of Flat Plate Solar Air Heater

    Directory of Open Access Journals (Sweden)

    Rajendra Karwa

    2014-01-01

    Full Text Available The paper presents results of an analysis carried out using a mathematical model to find the effect of the uncertainties, variations, and tolerances in design and ambient parameters on the thermohydraulic performance of flat plate solar air heater. Analysis shows that, for the range of flow rates considered, a duct height of 10 mm is preferred from the thermohydraulic consideration. The thermal efficiency changes by about 2.6% on variation in the wind heat transfer coefficient, ±5 K variation in sky temperature affects the efficiency by about ±1.3%, and solar insolation variation from 500 to 1000 Wm−2 affects the efficiency by about −1.5 to 1.3% at the lowest flow rate of 0.01 kgs−1 m−2 of the absorber plate with black paint. In general, these effects reduce with increase in flow rate and are lower for collector with selective coating on the absorber plate surface. The tolerances in the duct height and absorber plate emissivity should be small while positive tolerance of 3° in the collector slope for winter operation and ±3° for year round operation, and a positive tolerance for the gap between the absorber plate and glass cover at nominal value of 40 mm are recommended.

  12. The flat-plate plant-microbial fuel cell: the effect of a new design on internal resistances

    Directory of Open Access Journals (Sweden)

    Helder Marjolein

    2012-09-01

    Full Text Available Abstract Due to a growing world population and increasing welfare, energy demand worldwide is increasing. To meet the increasing energy demand in a sustainable way, new technologies are needed. The Plant-Microbial Fuel Cell (P-MFC is a technology that could produce sustainable bio-electricity and help meeting the increasing energy demand. Power output of the P-MFC, however, needs to be increased to make it attractive as a renewable and sustainable energy source. To increase power output of the P-MFC internal resistances need to be reduced. With a flat-plate P-MFC design we tried to minimize internal resistances compared to the previously used tubular P-MFC design. With the flat-plate design current and power density per geometric planting area were increased (from 0.15 A/m2 to 1.6 A/m2 and from 0.22 W/m2 to and 0.44 W/m2as were current and power output per volume (from 7.5 A/m3 to 122 A/m3 and from 1.3 W/m3 to 5.8 W/m3. Internal resistances times volume were decreased, even though internal resistances times membrane surface area were not. Since the membrane in the flat-plate design is placed vertically, membrane surface area per geometric planting area is increased, which allows for lower internal resistances times volume while not decreasing internal resistances times membrane surface area. Anode was split into three different sections on different depths of the system, allowing to calculate internal resistances on different depths. Most electricity was produced where internal resistances were lowest and where most roots were present; in the top section of the system. By measuring electricity production on different depths in the system, electricity production could be linked to root growth. This link offers opportunities for material-reduction in new designs. Concurrent reduction in material use and increase in power output brings the P-MFC a step closer to usable energy density and economic feasibility.

  13. Exergy efficiency analysis of a flat plate solar collector using graphene based nanofluid

    Science.gov (United States)

    Said, Z.; Alim, M. A.; Janajreh, Isam

    2015-10-01

    The thermal efficiency of a flat plate solar thermal collector is largely affected by the thermal conductivity of the fluid used. In this paper, we theoretically analyzed the heat transfer performance, the entropy generation rate, and the exergy efficiency of the two different graphene based nanofluids (graphene/Acetone and graphene/water). From the analyses, it is revealed that by inserting a small amount of graphene nanoparticles in water, exergy efficiency could be enhanced by 21%, comparing to conventional fluids and entropy generation is decreased by 4%. However, the graphene/water nanofluid shows a lower entropy generation. This characteristic suggests that graphene/water nanofluid is a better candidate for flat solar thermal application.

  14. Solar radiation data manual for flat-plate and concentrating collectors

    Energy Technology Data Exchange (ETDEWEB)

    Dunlap, M.A. [ed.; Marion, W.; Wilcox, S.

    For designers and engineers of solar energy-related systems, the Solar Radiation Data Manual for Flat-Plate and Concentrating Collectors gives the solar resource available for various types of collectors for the US and its territories. The data in the manual were modeled using hourly values of direct beam and diffuse horizontal solar radiation from the National Solar Radiation Data Base (NSRDB). The NSRDB contains modeled (93%) and measured (7%) global horizontal, diffuse horizontal, and direct beam solar radiation for 1961-1990.

  15. Model-supported phototrophic growth studies with Scenedesmus obtusiusculus in a flat-plate photobioreactor.

    Science.gov (United States)

    Koller, Anja Pia; Löwe, Hannes; Schmid, Verena; Mundt, Sabine; Weuster-Botz, Dirk

    2017-02-01

    Light-dependent growth of microalgae can vary remarkably depending on the cultivation system and microalgal strain. Cell size and the pigmentation of each strain, as well as reactor geometry have a great impact on absorption and scattering behavior within a photobioreactor. In this study, the light-dependent, cell-specific growth kinetics of a novel green algae isolate, Scenedesmus obtusiusculus, was studied in a LED-illuminated flat-plate photobioreactor on a lab-scale (1.8 L, 0.09 m2 ). First, pH-controlled batch processes were performed with S. obtusiusculus at different constant incident photon flux densities. The best performance was achieved by illuminating S. obtusiusculus with 1400 μmol photons m-2  s-1 at the surface of the flat-plate photobioreactor, resulting in the highest biomass concentration (4.95 ± 0.16 gCDW  L-1 within 3.5 d) and the highest specific growth rate (0.22 h-1 ). The experimental data were used to identify the kinetic parameters of different growth models considering light inhibition for S. obtusiusculus. Light attenuation within the flat-plate photobioreactor was considered by varying light transfer models. Based on the identified kinetic growth model of S. obtusiusculus, an optimum growth rate of 0.22 h-1 was estimated at a mean integral photon flux density of 1072 μmol photons m-2  s-1 with the Beer-Lambert law and 1590 μmol photons m-2  s-1 with Schuster's light transfer model in the flat-plate photobioreactor. LED illumination was, thus, increased to keep the identified optimum mean integral photon flux density constant in the batch process assuming Schuster's light transfer model. Compared to the same constant incident photon flux density (1590 μmol photons m-2  s-1 ), biomass concentration was up to 24% higher using the lighting profile until a dry cell mass concentration of 14.4 ± 1.4 gCDW  L-1 was reached. Afterward, the biomass concentration remained constant, whereas cell growth

  16. Analysis of Blasius Equation for Flat-Plate Flow with Infinite Boundary Value

    DEFF Research Database (Denmark)

    Miansari, M. O.; Miansari, M. E.; Barari, Amin

    2010-01-01

    and write the nonlinear differential equation in the state space format, and then solve the initial value problem instead of boundary value problem. The significance of linear part is a key factor in convergence. A first seen linear part may lead to an unstable solution, therefore an extra term is added......This paper applies the homotopy perturbation method (HPM) to determine the well-known Blasius equation with infinite boundary value for Flat-plate Flow. We study here the possibility of reducing the momentum and continuity equations to ordinary differential equations by a similarity transformation...

  17. Monitoring of a flat plate solar thermal field supplying process heat

    Directory of Open Access Journals (Sweden)

    Cozzini Marco

    2016-01-01

    Full Text Available The article reports the performance data of a flat plate collector field installed in Austria and supplying process heat to a meat factory, up to a temperature of about 95 °C. The presented data span an entire year, thereby including seasonal effects and allowing for a full characterization of the system performances. Sensor uncertainty is also discussed in detail. Finally, a bin method analysis of the field efficiency is provided. To this purpose, different operating conditions are concisely represented by the so-called reduced temperature, typically used in solar collector applications.

  18. Numerical Analysis of Noise Generation from a Protuberance on a Flat Plate

    OpenAIRE

    古川, 拓; 中村, 佳朗; 小池, 勝; 片岡, 拓也; Taku, Furukawa; Yoshiaki, Nakamura; Masaru, Koike; Takuya, Kataoka; 名大工; 名大工; 三菱自工; 三菱自工; Graduate School of Eng., Nagoya University; Dept. of Aerospace Eng., Nagoya University; Mitsubishi Motors Co.

    2000-01-01

    Aerodynamic noise generated from a small protuberance on a flat plate are numerically simulated. The flow speed is a low Mach number (U_∞=40m/s), and two shapes of protuberance : a forward facing step and a fence are calculated. Noise generation and its propergation are examined by solving the 2D N-S equations to see small pressure fluctuations in the far-field. These protuberance shapes affect the flow patterns near the wall, such as vortices or the area of separation. The analysis of FFT sh...

  19. MHD Natural Convection with Convective Surface Boundary Condition over a Flat Plate

    Directory of Open Access Journals (Sweden)

    Mohammad M. Rashidi

    2014-01-01

    Full Text Available We apply the one parameter continuous group method to investigate similarity solutions of magnetohydrodynamic (MHD heat and mass transfer flow of a steady viscous incompressible fluid over a flat plate. By using the one parameter group method, similarity transformations and corresponding similarity representations are presented. A convective boundary condition is applied instead of the usual boundary conditions of constant surface temperature or constant heat flux. In addition it is assumed that viscosity, thermal conductivity, and concentration diffusivity vary linearly. Our study indicates that a similarity solution is possible if the convective heat transfer related to the hot fluid on the lower surface of the plate is directly proportional to (x--1/2 where x- is the distance from the leading edge of the solid surface. Numerical solutions of the ordinary differential equations are obtained by the Keller Box method for different values of the controlling parameters associated with the problem.

  20. Effects of jet decay rate on jet induced loads on a flat plate

    Science.gov (United States)

    Kuhlman, J. M.; Warcup, R. W.

    1977-01-01

    Experimental modelling of the interaction between a jet and an aircraft wing or fuselage in VTOL aircraft was undertaken using a cold jet exiting perpendicular to a flat plate in a uniform cross-flow. Effects of jet decay rate and jet-to-cross-flow velocity ratio, R, on the induced load distribution were investigated. Jet decay rate was increased by using cylindrical centerbodies submerged in the jet nozzle, which caused nonuniform initial jet velocity profiles. Quicker jet decay rate, corresponding to the presence of a centerbody, resulted in as much as 50% reduction in the induced pressure loads on the plate. This has implications in interpretation of results from earlier VTOL model studies of jet induced loads, where the jets have often had relatively slow decay rates due to uniform initial velocity profiles

  1. Energy and exergy analysis of a new flat-plate solar air heater having different obstacles on absorber plates

    Energy Technology Data Exchange (ETDEWEB)

    Akpinar, Ebru Kavak; Kocyigit, Fatih [Mechanical Engineering Department, Firat University, 23279 Elazig (Turkey)

    2010-11-15

    This study experimentally investigates performance analysis of a new flat-plate solar air heater (SAH) with several obstacles (Type I, Type II, Type III) and without obstacles (Type IV). Experiments were performed for two air mass flow rates of 0.0074 and 0.0052 kg/s. The first and second laws of efficiencies were determined for SAHs and comparisons were made among them. The values of first law efficiency varied between 20% and 82%. The values of second law efficiency changed from 8.32% to 44.00%. The highest efficiency were determined for the SAH with Type II absorbent plate in flow channel duct for all operating conditions, whereas the lowest values were obtained for the SAH without obstacles (Type IV). The results showed that the efficiency of the solar air collectors depends significantly on the solar radiation, surface geometry of the collectors and extension of the air flow line. The largest irreversibility was occurring at the SAH without obstacles (Type IV) collector in which collector efficiency is smallest. At the end of this study, the energy and exergy relationships are delivered for different SAHs. (author)

  2. Pilot Experimental Tests on Punching Shear Strength of Flat Plates Reinforced with Stirrups Punching Shear Reinforcement

    Directory of Open Access Journals (Sweden)

    Mohamed Hassan

    2017-03-01

    Full Text Available Flat plates are favor structure systems usually used in parking garages and high-rise buildings due to its simplicity for construction. However, flat plates have some inherent structural problems, due to high shear stress surrounding the supporting columns which cause a catastrophic brittle type of failure called "Punching Shear Failure". Several solutions are used to avoid punching shear failure, including the use of drop panels or punching shear reinforcement. The latter is being a more sophisticated solution from the structural ductility, the architectural and the economical point of view. This study aims at investigating the effect of stirrups as shear reinforcement in enhancing the punching strength of interior slab-column connections. A total of four full-scale interior slab-column connections were tested up to failure. All slabs had a side length of 1700 mm and 160 mm thickness with 200 mm x 200 mm square column. The test parameters were the presence of shear reinforcement and stirrups concentration around the supporting column. The test results showed that the distribution of stirrups over the critical punching shear zone was an efficient solution to enhance not only the punching shear capacity but also the ductility of the connection. Furthermore, the concentrating of stirrups shear reinforcement in the vicinity of the column for the tested slabs increases the punching shear capacity by 13 % compared to the uniform distribution at same amount of shear reinforcement.

  3. Experimental testing of various heat transfer structures in a flat plate thermal energy storage unit

    Science.gov (United States)

    Johnson, Maike; Fiß, Michael; Klemm, Torsten

    2016-05-01

    For solar process heat applications with steam as the working fluid and varying application parameters, a novel latent heat storage concept has been developed using an adaptation of a flat plate heat exchanger as the storage concept. Since the pressure level in these applications usually does not exceed 30 bar, an adaptation with storage material chambers arranged between heat transfer medium chambers is possible. Phase change materials are used as the storage medium, so that the isothermal evaporation of steam during discharging of the storage is paired with the isothermal solidification of the storage material. Heat transfer structures can be inserted into the chambers to adjust the power level for a given application. By combining the required number of flat plate heat exchanger compartments and inserting the appropriate heat transfer structure, the design can easily be adjusted for the required power level and capacity for a specific application. Within this work, the technical feasibility of this concept is proven. The dependence of the operating characteristics on the geometry of the heat exchanger is identified. A focus is on varying the power density by integrating conductive heat structures in the PCM.

  4. Factors relating to the degradation of materials in flat plate solar collectors

    Energy Technology Data Exchange (ETDEWEB)

    Wennerholm, H.; Vejsig Pedersen, P.

    1986-05-01

    The widespread use of flat plate solar collectors is being held back by lack of confidence in the long term durability of the component materials. Every material has a particular set or range of conditions under which it exhibits greatest ability to maintain its most desirable properties. This paper presents a review of the suitability of specific materials for components in flat plate solar collectors during exposure to weather conditions. Ambient factors that influence the atmospheric degradiation of materials are weather conditions, biological factors, mechanical factors, combinations of incompatible materials and application conditions. Weather conditions are, solar radiation, temperature, precipitation, humidity, wind, normal air components, and pollution. The most important factor promoting atmospheric corrosion of metals is the percentage of time when the critical humidity is exceeded. This period is called the time-of-wetness. Corrosion rates of most metals normally accelerate when metals are exposed to polluted environments. The agents constituting pollution that have been identified with corrosion can be listed as sulphur dioxide, hydrogen sulphide, ammonia, nitrogen oxides, sodium chloride, and particulate matter. The ultraviolet component in solar radiation plays an important role in the decomposition of organic materials. Other factors are heat, high humidities, oxygen, ozone, micro-biologic organisms, air pollution substances, wind, and dust. Synergistic associations are capable of effecting chemical transformations which are beyond the separate abilites of each degradation factor. And that affect both inorganic and organic materials. (author) 67 refs.

  5. Can Integrated Micro-Optical Concentrator Technology Revolutionize Flat-Plate Photovoltaic Solar Energy Harvesting?

    Science.gov (United States)

    Haney, Michael W.

    2015-12-01

    The economies-of-scale and enhanced performance of integrated micro-technologies have repeatedly delivered disruptive market impact. Examples range from microelectronics to displays to lighting. However, integrated micro-scale technologies have yet to be applied in a transformational way to solar photovoltaic panels. The recently announced Micro-scale Optimized Solar-cell Arrays with Integrated Concentration (MOSAIC) program aims to create a new paradigm in solar photovoltaic panel technology based on the incorporation of micro-concentrating photo-voltaic (μ-CPV) cells. As depicted in Figure 1, MOSAIC will integrate arrays of micro-optical concentrating elements and micro-scale PV elements to achieve the same aggregated collection area and high conversion efficiency of a conventional (i.e., macro-scale) CPV approach, but with the low profile and mass, and hopefully cost, of a conventional non-concentrated PV panel. The reduced size and weight, and enhanced wiring complexity, of the MOSAIC approach provide the opportunity to access the high-performance/low-cost region between the conventional CPV and flat-plate (1-sun) PV domains shown in Figure 2. Accessing this portion of the graph in Figure 2 will expand the geographic and market reach of flat-plate PV. This talk reviews the motivation and goals for the MOSAIC program. The diversity of the technical approaches to micro-concentration, embedded solar tracking, and hybrid direct/diffuse solar resource collection found in the MOSAIC portfolio of projects will also be highlighted.

  6. Numerical Investigation of Deviation of Phase Change Characteristics of Horizontal and Vertical Flat Heat Pipe Configurations

    Directory of Open Access Journals (Sweden)

    Rakesh Hari

    2015-12-01

    Full Text Available The flow characteristics in the porous wick of a flat heat pipe subjected to boiling and condensation are analysed here using two-phase mixture model. Steady laminar boundary layer flow in the capillary wick structure is considered for both vertical and horizontal orientations. The governing boundary layer partial differential equations are simplified using similarity transformation. The transformed equations are then solved numerically by using shooting iterative technique. Investigation was carried out for the effects of the involved parameters such as saturation and temperature across the boundary layer. The behaviour of non-dimensional numbers due to the orientation of the heat pipe is also discussed. The study confirms that orientation plays a significant role in flow and temperature field.

  7. Analysis of behavior of simply supported flat plates compressed beyond the buckling load into the plastic range

    Science.gov (United States)

    Mayers, J; Budiansky, Bernard

    1955-01-01

    An analysis is presented of the postbuckling behavior of a simply supported square flat plate with straight edges compressed beyond the buckling load into the plastic range. The method of analysis involves the application of a variational principle of the deformation theory of plasticity in conjunction with computations carried out on a high-speed calculating machine. Numerical results are obtained for several plate proportions and for one material. The results indicate plate strengths greater than those that have been found experimentally on plates that do not satisfy straight-edge conditions. (author)

  8. Improved Thermal-Vacuum Compatible Flat Plate Radiometric Source For System-Level Testing Of Optical Sensors

    Science.gov (United States)

    Schwarz, Mark A.; Kent, Craig J.; Bousquet, Robert; Brown, Steven W.

    2016-01-01

    In this work, we describe an improved thermal-vacuum compatible flat plate radiometric source which has been developed and utilized for the characterization and calibration of remote optical sensors. This source is unique in that it can be used in situ, in both ambient and thermal-vacuum environments, allowing it to follow the sensor throughout its testing cycle. The performance of the original flat plate radiometric source was presented at the 2009 SPIE1. Following the original efforts, design upgrades were incorporated into the source to improve both radiometric throughput and uniformity. The pre-thermal-vacuum (pre-TVAC) testing results of a spacecraft-level optical sensor with the improved flat plate illumination source, both in ambient and vacuum environments, are presented. We also briefly discuss potential FPI configuration changes in order to improve its radiometric performance.

  9. Experimental study of turbulent round jet flow impinging on a square cylinder laid on a flat plate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam-Shin [Institut de Mecanique des Fluides de Toulouse, Allee du Pr. Camille Soula, 31400 Toulouse (France)], E-mail: kim@imft.fr; Giovannini, Andre [Institut de Mecanique des Fluides de Toulouse, Allee du Pr. Camille Soula, 31400 Toulouse (France)], E-mail: giova@imft.fr

    2007-12-15

    A turbulent axisymmetric air jet impinging on a square cylinder mounted on a flat plate has been studied experimentally. Turbulence statistics and flow's topology were investigated. When the surface was heated through uniform heat flux, local heat transfer coefficient was measured. The jet from a long round pipe, 75 pipe diameters (D) in length, at Reynolds number of 23,000, impinged vertically on the square cylinder (3D x 3D x 43D). Measurements were performed using particle image velocimetry, flow visualization using fluorescent dye and infrared thermography. The flow's topology demonstrated a three-dimensional recirculation after separating from the square cylinder and a presence of foci between the bottom corner and the recirculation's detachment line. The distribution of heat transfer coefficient was explained by the influence of these flow's structures and the advection of kinetic energy. On the impingement wall of the square cylinder, a secondary peak in heat transfer coefficient was observed. Its origin can be attributed to very pronounced shear production coupled with the external turbulence coming from the free jet.

  10. Reynolds number influence on the formation of vortical structures on a pitching flat plate.

    Science.gov (United States)

    Widmann, Alexander; Tropea, Cameron

    2017-02-06

    The impact of chord-based Reynolds number on the formation of leading-edge vortices (LEVs) on unsteady pitching flat plates is investigated. The influence of secondary flow structures on the shear layer feeding the LEV and the subsequent topological change at the leading edge as the result of viscous processes are demonstrated. Time-resolved velocity fields are measured using particle image velocimetry simultaneously in two fields of view to correlate local and global flow phenomena in order to identify unsteady boundary-layer separation and the subsequent flow structures. Finally, the Reynolds number is identified as a parameter that is responsible for the transition in mechanisms leading to LEV detachment from an aerofoil, as it determines the viscous response of the boundary layer in the vortex-wall interaction.

  11. Comparison of DAC and MONACO DSMC Codes with Flat Plate Simulation

    Science.gov (United States)

    Padilla, Jose F.

    2010-01-01

    Various implementations of the direct simulation Monte Carlo (DSMC) method exist in academia, government and industry. By comparing implementations, deficiencies and merits of each can be discovered. This document reports comparisons between DSMC Analysis Code (DAC) and MONACO. DAC is NASA's standard DSMC production code and MONACO is a research DSMC code developed in academia. These codes have various differences; in particular, they employ distinct computational grid definitions. In this study, DAC and MONACO are compared by having each simulate a blunted flat plate wind tunnel test, using an identical volume mesh. Simulation expense and DSMC metrics are compared. In addition, flow results are compared with available laboratory data. Overall, this study revealed that both codes, excluding grid adaptation, performed similarly. For parallel processing, DAC was generally more efficient. As expected, code accuracy was mainly dependent on physical models employed.

  12. PV Reliability Development Lessons from JPL's Flat Plate Solar Array Project

    Science.gov (United States)

    Ross, Ronald G., Jr.

    2013-01-01

    Key reliability and engineering lessons learned from the 20-year history of the Jet Propulsion Laboratory's Flat-Plate Solar Array Project and thin film module reliability research activities are presented and analyzed. Particular emphasis is placed on lessons applicable to evolving new module technologies and the organizations involved with these technologies. The user-specific demand for reliability is a strong function of the application, its location, and its expected duration. Lessons relative to effective means of specifying reliability are described, and commonly used test requirements are assessed from the standpoint of which are the most troublesome to pass, and which correlate best with field experience. Module design lessons are also summarized, including the significance of the most frequently encountered failure mechanisms and the role of encapsulate and cell reliability in determining module reliability. Lessons pertaining to research, design, and test approaches include the historical role and usefulness of qualification tests and field tests.

  13. Boundary Layer Flow and Heat Transfer of FMWCNT/Water Nanofluids over a Flat Plate

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Safaei

    2016-09-01

    Full Text Available In the present study, the heat transfer and flow of water/FMWCNT (functionalized multi-walled carbon nanotube nanofluids over a flat plate was investigated using a finite volume method. Simulations were performed for velocity ranging from 0.17 mm/s to 1.7 mm/s under laminar regime and nanotube concentrations up to 0.2%. The 2-D governing equations were solved using an in-house FORTRAN code. For a specific free stream velocity, the presented results showed that increasing the weight percentage of nanotubes increased the Nusselt number. However, an increase in the solid weight percentage had a negligible effect on the wall shear stress. The results also indicated that increasing the free stream velocity for all cases leads to thinner boundary layer thickness, while increasing the FMWCNT concentration causes an increase in the boundary layer thickness.

  14. A preliminary investigation of boundary-layer transition along a flat plate with adverse pressure gradient

    Science.gov (United States)

    Von Doenhoff, Albert E

    1938-01-01

    Boundary-layer surveys were made throughout the transition region along a smooth flat plate placed in an airstream of practically zero turbulence and with an adverse pressure gradient. The boundary-layer Reynolds number at the laminar separation point was varied from 1,800 to 2,600. The test data, when considered in the light of certain theoretical deductions, indicated that transition probably began with separation of the laminar boundary layer. The extent of the transition region, defined as the distance from a calculated laminar separation point to the position of the first fully developed turbulent boundary-layer profile, could be expressed as a constant Reynolds number run of approximately 70,000. Some speculations are presented concerning the application of the foregoing concepts, after certain assumptions have been made, to the problem of the connection between transition on the upper surface of an airfoil at high angles of attack and the maximum lift.

  15. Development of flat-plate solar collectors for the heating and cooling of buildings

    Science.gov (United States)

    Ramsey, J. W.; Borzoni, J. T.; Holland, T. H.

    1975-01-01

    The relevant design parameters in the fabrication of a solar collector for heating liquids were examined. The objective was to design, fabricate, and test a low-cost, flat-plate solar collector with high collection efficiency, high durability, and requiring little maintenance. Computer-aided math models of the heat transfer processes in the collector assisted in the design. The preferred physical design parameters were determined from a heat transfer standpoint and the absorber panel configuration, the surface treatment of the absorber panel, the type and thickness of insulation, and the number, spacing and material of the covers were defined. Variations of this configuration were identified, prototypes built, and performance tests performed using a solar simulator. Simulated operation of the baseline collector configuration was combined with insolation data for a number of locations and compared with a predicted load to determine the degree of solar utilization.

  16. Multi-objective genetic algorithm for the optimization of a flat-plate solar thermal collector.

    Science.gov (United States)

    Mayer, Alexandre; Gaouyat, Lucie; Nicolay, Delphine; Carletti, Timoteo; Deparis, Olivier

    2014-10-20

    We present a multi-objective genetic algorithm we developed for the optimization of a flat-plate solar thermal collector. This collector consists of a waffle-shaped Al substrate with NiCrOx cermet and SnO(2) anti-reflection conformal coatings. Optimal geometrical parameters are determined in order to (i) maximize the solar absorptance α and (ii) minimize the thermal emittance ε. The multi-objective genetic algorithm eventually provides a whole set of Pareto-optimal solutions for the optimization of α and ε, which turn out to be competitive with record values found in the literature. In particular, a solution that enables α = 97.8% and ε = 4.8% was found.

  17. Molecular dynamics simulations of ultrathin water film confined between flat diamond plates

    Directory of Open Access Journals (Sweden)

    A.V. Khomenko

    2008-12-01

    Full Text Available Molecular dynamics simulations of ultrathin water film confined between atomically flat rigid diamond plates are described. Films with thickness of one and two molecular diameters are concerned and TIP4P model is used for water molecules. Dynamical and equilibrium characteristics of the system for different values of the external load and shear force are investigated. An increase of the external load causes the transition of the film to a solidlike state. This is manifested in a decrease of the diffusion constant and in the ordering of the liquid molecules into quasidiscrete layers. For two-layer film under high loads, the molecules also become ordered parallel to the surfaces. Time dependencies of the friction force and the changes of its average value with the load are obtained. In general, the behaviour of the studied model is consistent with the experimental results obtained for simple liquids with spherical molecules.

  18. Development and modeling of a flat plate serpentine reactor for photocatalytic degradation of 17-ethinylestradiol.

    Science.gov (United States)

    Wang, Dawei; Li, Yi; Zhang, Wenlong; Wang, Qing; Wang, Peifang; Wang, Chao

    2013-04-01

    A flat plate serpentine reactor modified from ultraviolet disinfection pool in municipal wastewater treatment plants was developed for the removal of 17-ethinylestradiol (EE2) for the first time. The photocatalytic degradation performance of EE2 was investigated in this serpentine reactor under different conditions such as inlet concentrations, loaded catalyst concentrations, incident radiations fluxes, and flow velocities. More than 98% of EE2 was removed under certain conditions within 120 min. An integrated model including a six-flux adsorption-scattering model and a modified flow diffusion model was established to investigate the effect of radiation field and flow velocities, respectively. A satisfactory agreement was observed between the model simulation and experimental results, showing a potential for design and scale-up of photocatalytic reactor for wastewater treatment.

  19. Effects of design on cost of flat-plate solar photovoltaic arrays for terrestrial central station power applications

    Science.gov (United States)

    Tsou, P.; Stolte, W.

    1978-01-01

    The paper examines the impact of module and array designs on the balance-of-plant costs for flat-plate terrestrial central station power applications. Consideration is given to the following types of arrays: horizontal, tandem, augmented, tilt adjusted, and E-W tracking. The life-cycle cost of a 20-year plant life serves as the costing criteria for making design and cost tradeoffs. A tailored code of accounts is developed for determining consistent photovoltaic power plant costs and providing credible photovoltaic system cost baselines for flat-plate module and array designs by costing several varying array design approaches.

  20. The response of a flat plate boundary layer to an orthogonally arranged dielectric barrier discharge actuator

    Science.gov (United States)

    Gibson, B. A.; Arjomandi, M.; Kelso, R. M.

    2012-01-01

    The jetting characteristics of dielectric barrier discharge (DBD) actuators make these devices suitable for augmenting boundary layer flows. The associated change to the hydrodynamic stability of the fluid arising from the actuator provides a mechanism through which a DBD-based laminar flow control (LFC) system can be developed. Historically, DBD actuators with electrodes arranged parallel to each other have been used for LFC with mixed results. An alternative is to use an actuator with electrodes placed orthogonally to each other. Orthogonally arranged actuators exhibit different jetting characteristics to conventional ones, and as such understanding the effect that these actuators have on the mean velocity profile within a flat plate boundary layer is of significant interest to the development of DBD-based LFC technology. In this investigation, the velocity distribution within a flat plate boundary layer in a zero pressure gradient is measured in response to the operation of an orthogonally arranged actuator. The results suggest that significant thinning of the boundary layer can be realized with an orthogonally arranged actuator, over a short distance downstream of the device, and used in conjunction with a subtle suction effect, this thinning can be exacerbated. However, further downstream, rapid thickening of the layer, supported by a decrease in the shape factor of the flow suggests that the layer becomes unstable, in an accelerated fashion, to the presence of the actuator. Hence the stability of the layer is found to be significantly altered by the presence of the orthogonally arranged actuator, a requisite for a LFC system. However, since the actuator produces a destabilizing effect, the development of a successful LFC system based on orthogonal actuators will require further work.

  1. Solar energy dryer kinetics using flat-plate finned collector and forced convection for potato drying

    Science.gov (United States)

    Batubara, Fatimah; Misran, Erni; Dina, Sari Farah; Heppy

    2017-06-01

    Research on potato drying using the indirect solar dryer with flat-plate finned collector and forced convection has been done. The research was conducted at the outdoor field of Laboratory of Institute for Research and Standardization of Industry on June 14th-23rd, 2016 from 9:00 am to 4:00 pm. This research aims to obtain the drying kinetics model of potato (Solanumtuberosum L.) using an indirect solar dryer's (ISD) with flat plate-finned collector and forced convection. The result will be compared to the open sun drying (OSD) method. Weather conditions during the drying process took place as follows; surrounding air temperature was in the range 27 to 34.7 °C, relative humidity (RH) 29.5 to 61.0% and the intensity of solar radiation 105.6 to 863.1 Watt/m2. The dried potato thicknesses were 1.0 cm, 1.5 cm and 2.0 cm, with the average initial water content of 76.46%. The average temperature in the collector chamber ranged from 42.2 to 57.4 °C and the drying chamber was at 46.2 °C. The best drying result was obtained from a sample size of 1 cm thickness using the IDS method with an average drying rate of 0.018 kg H2O per kg dry-weight.hour and the water content was constant at 5.02% in 21 hours of drying time. The most suitable kinetics model is Page model, equation MR = exp (-0.049 t1,336) for 1.0 cm thickness, exp (-0.066 t1,222) for 1.5 cm thickness and exp (-0.049 t1,221) for 2.0 cm thickness. The quality of potato drying using ISD method is better than using OSD which can be seen from the color produced.

  2. Design, construction and evaluation of solar flat-plate collector simulator based on the thermohydraulic coefficient

    Directory of Open Access Journals (Sweden)

    H Rahmati Aidinlou

    2017-05-01

    Full Text Available Introduction Increasing the area of absorber plate between the flowed air through the duct can be accomplished by corrugating the absorber plate or by using the artificial roughness underside of the absorber plate as the commercial methods for enhancing the thermohydraulic performance of the flat plate solar air heaters. Evaluation of this requires the construction of separated solar air heater which is costly and time consuming. The constructed solar flat-plate collector simulator can be a sufficient solution for obtaining the heat transfer and thermodynamic parameters for evaluating the absorber plate. The inclined broken roughness was chosen as the optimum roughness which is surrounded by three aluminum smooth walls. Materials and Methods The duct for both smooth and roughened plate have been constructed based on the ASHRAE 93-2010 standard. In order to achieve a fully thermal and hydraulic developed flow, the plenum is constructed. The centrifugal fan is considered by applying the required air volume at the pressure drop obtained by the duct, plenum and the orifice meter. The TSI velocity-meter 8355 is used to measure the velocity of air crossing through the pipe connected to the centrifugal fan. The micro manometer Kimo CPE310-s with the resolution of 0.1 Pa is used to measure the pressure drop across the test section of the smooth and roughened duct. The LM35 sensors are used to measure the absorber plate and air temperature through the test section. Obtained parameters are used to calculate the Nusselt number and friction factor across the test section for smooth and roughened absorber plate. The Nusselt number and friction factor parameters which is obtained for smooth absorber plate based on experimental set-up, is compared with Dittus-Bolter and Blasius equations, respectively, for validating the simulator. By calculating the Nusselt number and friction factor, Stanton number is obtained based on the equation (6, and thermohydraulic

  3. Microscale 3D collagen cell culture assays in conventional flat-bottom 384-well plates.

    Science.gov (United States)

    Leung, Brendan M; Moraes, Christopher; Cavnar, Stephen P; Luker, Kathryn E; Luker, Gary D; Takayama, Shuichi

    2015-04-01

    Three-dimensional (3D) culture systems such as cell-laden hydrogels are superior to standard two-dimensional (2D) monolayer cultures for many drug-screening applications. However, their adoption into high-throughput screening (HTS) has been lagging, in part because of the difficulty of incorporating these culture formats into existing robotic liquid handling and imaging infrastructures. Dispensing cell-laden prepolymer solutions into 2D well plates is a potential solution but typically requires large volumes of reagents to avoid evaporation during polymerization, which (1) increases costs, (2) makes drug penetration variable and (3) complicates imaging. Here we describe a technique to efficiently produce 3D microgels using automated liquid-handling systems and standard, nonpatterned, flat-bottomed, 384-well plates. Sub-millimeter-diameter, cell-laden collagen gels are deposited on the bottom of a ~2.5 mm diameter microwell with no concerns about evaporation or meniscus effects at the edges of wells, using aqueous two-phase system patterning. The microscale cell-laden collagen-gel constructs are readily imaged and readily penetrated by drugs. The cytotoxicity of chemotherapeutics was monitored by bioluminescence and demonstrated that 3D cultures confer chemoresistance as compared with similar 2D cultures. Hence, these data demonstrate the importance of culturing cells in 3D to obtain realistic cellular responses. Overall, this system provides a simple and inexpensive method for integrating 3D culture capability into existing HTS infrastructure. © 2014 Society for Laboratory Automation and Screening.

  4. Influence of nanofluids on the efficiency of Flat-Plate Solar Collectors (FPSC)

    Science.gov (United States)

    Nejad, Marjan B.; Mohammed, H. A.; Sadeghi, O.; Zubeer, Swar A.

    2017-11-01

    A numerical investigation is performed using finite volume method to study the laminar heat transfer in a three-dimensional flat-plate solar collector using different nanofluids as working fluids. Three nanofluids with different types of nanoparticles (Ag, MWCNT and Al2O3 dispersed in water) with 1-2 wt% volume fractions are analyzed. A constant heat flux, equivalent to solar radiation absorbed by the collector, is applied at the top surface of the absorber plate. In this study, several parameters including boundary conditions (different volume flow rates, different fluid inlet temperatures and different solar irradiance at Skudai, Malaysia), different types of nanoparticles, and different solar collector tilt angles are investigated to identify their effects on the heat transfer performance of FPSC. The numerical results reveal that the three types of nanofluid enhance the thermal performance of solar collector compared to pure water and FPSC with Ag nanofluid has the best thermal performance enhancement. For all the cases, the collector efficiency increased with the increase of volume flow rate while fluid outlet temperature decreased. It is found that FPSC with tilt angle of 10° and fluid inlet temperature of 301.15 K has the best thermal performance.

  5. Influence of nanofluids on the efficiency of Flat-Plate Solar Collectors (FPSC

    Directory of Open Access Journals (Sweden)

    Nejad Marjan B.

    2017-01-01

    Full Text Available A numerical investigation is performed using finite volume method to study the laminar heat transfer in a three-dimensional flat-plate solar collector using different nanofluids as working fluids. Three nanofluids with different types of nanoparticles (Ag, MWCNT and Al2O3 dispersed in water with 1–2 wt% volume fractions are analyzed. A constant heat flux, equivalent to solar radiation absorbed by the collector, is applied at the top surface of the absorber plate. In this study, several parameters including boundary conditions (different volume flow rates, different fluid inlet temperatures and different solar irradiance at Skudai, Malaysia, different types of nanoparticles, and different solar collector tilt angles are investigated to identify their effects on the heat transfer performance of FPSC. The numerical results reveal that the three types of nanofluid enhance the thermal performance of solar collector compared to pure water and FPSC with Ag nanofluid has the best thermal performance enhancement. For all the cases, the collector efficiency increased with the increase of volume flow rate while fluid outlet temperature decreased. It is found that FPSC with tilt angle of 10° and fluid inlet temperature of 301.15 K has the best thermal performance.

  6. Heat Transfer on a Flat Plate with Uniform and Step Temperature Distributions

    Science.gov (United States)

    Bahrami, Parviz A.

    2005-01-01

    Heat transfer associated with turbulent flow on a step-heated or cooled section of a flat plate at zero angle of attack with an insulated starting section was computationally modeled using the GASP Navier-Stokes code. The algebraic eddy viscosity model of Baldwin-Lomax and the turbulent two-equation models, the K- model and the Shear Stress Turbulent model (SST), were employed. The variations from uniformity of the imposed experimental temperature profile were incorporated in the computations. The computations yielded satisfactory agreement with the experimental results for all three models. The Baldwin- Lomax model showed the closest agreement in heat transfer, whereas the SST model was higher and the K-omega model was yet higher than the experiments. In addition to the step temperature distribution case, computations were also carried out for a uniformly heated or cooled plate. The SST model showed the closest agreement with the Von Karman analogy, whereas the K-omega model was higher and the Baldwin-Lomax was lower.

  7. Computational Analysis of Vortex Formation Over a Plunge Oscillating Flat Plate with Various Slip Conditions

    Science.gov (United States)

    Palmore, John; Sharif, Muhammad; Lang, Amy

    2010-11-01

    A thorough understanding of small scale aerodynamics is important for the design of micro air vehicles. Since they fly in the same Re regime as that of insects, these animals can provide biologically inspired designs. This study looks at how an alteration to the surface slip condition affects the aerodynamic flow over a wing at low Re. Butterflies have small scales (on the order of 100 microns in length) that line the surface of their wings, and it is hypothesized that these scales can affect the slip condition over their wings altering vortex formation and possibly leading to improved flight characteristics. As an initial test to this hypothesis, the flow over an infinitely thin, two-dimensional flat plate was studied using the CFD software FLUENT. The no-slip condition was modified by directly altering the shear stress distribution over the plate. In addition, the action of flapping was simulated by varying the angle of attack as a function of time between -60 and 60 degrees. Multiple shear stress distributions, varying from shear free to no-slip, and multiple flapping frequencies were tested to discern the effects on vortex formation; lift and drag were also analyzed.

  8. Flat plate solar collector for water pre-heating using concentrated solar power (CSP)

    Science.gov (United States)

    Peris, Leonard Sunny; Shekh, Md. Al Amin; Sarker, Imran

    2017-12-01

    Numerous attempt and experimental conduction on different methods to harness energy from renewable sources are being conducted. This study is a contribution to the purpose of harnessing solar energy as a renewable source by using flat plate solar collector medium to preheat water. Basic theory of solar radiation and heat convection in water (working fluid) has been combined with heat conduction process by using copper tubes and aluminum absorber plate in a closed conduit, covered with a glazed through glass medium. By this experimental conduction, a temperature elevation of 35°C in 10 minutes duration which is of 61.58% efficiency range (maximum) has been achieved. The obtained data and experimental findings are validated with the theoretical formulation and an experimental demonstration model. A cost effective and simple form of heat energy extraction method for space heating/power generation has been thoroughly discussed with possible industrial implementation possibilities. Under-developed and developing countries can take this work as an illustration for renewable energy utilization for sustainable energy prospect. Also a full structure based data to derive concentrated solar energy in any geographical location of Bangladesh has been outlined in this study. These research findings can contribute to a large extent for setting up any solar based power plant in Bangladesh irrespective of its installation type.

  9. A diagram for defined flat plate solar collector area for solar floor heating

    Energy Technology Data Exchange (ETDEWEB)

    Altuntop, N.; Tekin, Y. [Erciyes University, Dept. of Mechanical Engineering (Turkey); Cengel, Y.A. [Nevada Reno University, Dept. of Mechanical Engineering, NV (United States)

    2000-07-01

    In winters, one of the best ways to heat living areas by using the low- temperature - water obtained from flat-plate solar collectors is the floor heating. In floor heating, low temperature-water (30 + 60 deg C) can be used and heat can be stored in water when solar radiation is not possible. In this study, it is aimed to define collector surface needed to supply heat for floor heating. It is also aimed to define and explain the diagram developed for every heating months. The calculations about the sun geometry are used to define the amount of radiation coming in to the collectors. Formulations are made about the definition of solar radiation absorbed by the collectors, the total heat loss coefficient, and the collector plate surface temperature. These formulations are transformed in to the diagram. In addition, the studies, heat transfer calculations and design parameters about the floor of the heating areas are used. A combined collector floor heating diagram is obtained. This diagram is used to define collector surface area necessary to supply heat for floor heated places. In this diagram, the collector surface area is obtained by giving the heat capacity of the place area, floor surface temperature, approximate modulation distance of the floor, the elevation of city, collector slope angle, wind speed, sun shine lime and the amount of the solar radiation obtained from the solar radiation diagram. (authors)

  10. Earth Reflected Solar Radiation Incident upon an Arbitrarily Oriented Spinning Flat Plate

    Science.gov (United States)

    Cunningham, Fred G.

    1963-01-01

    A general derivation is given for the earth reflected solar radiation input to a flat plate--a solar cell paddle, for example--which is spinning about an axis coincident with the axis of symmetry of the satellite to which it is affixed. The resulting equations are written for the general case so that arbitrary orientations of the spin axis with respect to the earth-satellite line and arbitrary orientations of the normal to the plate with respect to the spin axis can be treated. No attempt is made to perform the resulting integrations because of the complexity of the equations; nor is there any attempt to delineate the integration limits for the general case. However, the equations governing these limits are given. The appendixes contain: the results, in graphical form, of two representative examples; the general computer program for the calculation is given in Fortran notation; and the results of a calculation of the distribution of albedo energy on the proposed Echo II satellite. The value of the mean solar constant used is 1.395 times 10 (sup 4) ergs per centimeters-squared per second; the mean albedo of the earth is assumed to be 0.34; and the earth is assumed to be a diffuse reflector.

  11. Use of a rotating cylinder to induce laminar and turbulent separation over a flat plate

    Science.gov (United States)

    Afroz, F.; Lang, A.; Jones, E.

    2017-06-01

    An innovative and easy technique using a rotating cylinder system has been implemented in a water tunnel experiment to generate an adverse pressure gradient (APG). The strength of the APG was varied through adjustment in the rotation speed and location of the cylinder. Then the technique was used for inducing a laminar separation bubble (LSB) and turbulent boundary layer (TBL) separation over a flat plate. A theoretical model to predict the pressure variation induced on the plate consists of an inviscid flow over a reverse doublet-like configuration of two counter rotating cylinders. This model quantified the pressure distribution with changes of cylinder speed and location. The dimensionless velocity ratio (VR) of the cylinder rotation rate to the mainstream velocity and gap to diameter ratio \\tfrac{G}{D} were chosen as the two main ways of varying the strength of the APG, which affects the nature and extent of the LSB as well as TBL separation. The experimental parametric study, using time-resolved digital particle image velocimetry, was then conducted in a water tunnel. The variation in height (h), length (l), and the separation point (S) of the LSB was documented due to the variation in the APG. The similar type of experimental parametric study was used to explore the unsteady, turbulent separation bubble in a 2D plane aligned with the flow and perpendicular to the plate. The mean detachment locations of TBL separation are determined by two different definitions: (i) back-flow coefficient (χ) = 50%, and (ii) location of start of negative mean skin friction coefficient (C f). They are in good agreement and separation bubble characteristics agreed well with results obtained using different methods thus proving the validity of the technique.

  12. NUMERICAL STUDY OF MICROPOLAR FLUID FLOW HEAT AND MASS TRANSFER OVER VERTICAL PLATE: EFFECTS OF THERMAL RADIATION AND MAGNETIC FIELD

    Directory of Open Access Journals (Sweden)

    REDHA ALOUAOUI

    2015-06-01

    Full Text Available In this paper, we examine the thermal radiation effect on heat and mass transfer in steady laminar boundary layer flow of an incompressible viscous micropolar fluid over a vertical flat plate, with the presence of a magnetic field. Rosseland approximation is applied to describe the radiative heat flux in the energy equation. The resulting similarity equations are solved numerically. Many results are obtained and representative set is displayed graphically to illustrate the influence of the various parameters on different profiles. The conclusion is drawn that the flow field, temperature, concentration and microrotation  as well as the skin friction coefficient and the both  local Nusselt and Sherwood numbers  are significantly influenced by Magnetic parameter, material parameter  and thermal radiation parameter.

  13. Numerical analysis of natural convection for non-Newtonian fluid conveying nanoparticles between two vertical parallel plates

    Science.gov (United States)

    Sahebi, S. A. R.; Pourziaei, H.; Feizi, A. R.; Taheri, M. H.; Rostamiyan, Y.; Ganji, D. D.

    2015-12-01

    In this paper, natural convection of non-Newtonian bio-nanofluids flow between two vertical flat plates is investigated numerically. Sodium Alginate (SA) and Sodium Carboxymethyl Cellulose (SCMC) are considered as the base non-Newtonian fluid, and nanoparticles such as Titania ( TiO2 and Alumina ( Al2O3 were added to them. The effective thermal conductivity and viscosity of nanofluids are calculated through Maxwell-Garnetts (MG) and Brinkman models, respectively. A fourth-order Runge-Kutta numerical method (NUM) and three Weighted Residual Methods (WRMs), Collocation (CM), Galerkin (GM) and Least-Square Method (LSM) and Finite-Element Method (FEM), are used to solve the present problem. The influence of some physical parameters such as nanofluid volume friction on non-dimensional velocity and temperature profiles are discussed. The results show that SCMC- TiO2 has higher velocity and temperature values than other nanofluid structures.

  14. Quantifying Station Quality from Residual Vertical Motions in the EarthScope Plate Boundary Observatory GPS Network

    Science.gov (United States)

    Puskas, C. M.; Phillips, D. A.; Meertens, C. M.; Herring, T.

    2016-12-01

    Vertical motions measured by GPS stations in the EarthScope Plate Boundary Observatory (PBO) network are a combination of tectonic motion, hydrologic loading processes, local volcanism, atmospheric loading, errors inherent to a satellite-based navigation system, and other local events. We take all the position time series in the PBO network and apply a linear and sinusoidal fit, and we also correct for offsets from earthquakes and equipment, and for post-seismic decay. The residuals can then be used as a starting point for station quality evaluations. Well-fit residuals for healthy stations should have low RMS values and plot as relatively flat time series, with bumps in the time series attributable to seasonal variations in hydrologic loading (e.g., an unusually wet or dry year). Exceptions for healthy stations without flat time series occur in regions with volcanism (affecting the vertical and horizontal components) and episodic tremor and slip (affecting horizontal components). In such cases healthy and unhealthy stations can be separated by examining various quality (QC) parameters from processing-derived errors to multipath to signal-to-noise ratios. Furthermore, otherwise healthy station may experience episodes of low-quality as equipment fails or the station is overgrown with vegetation or buried in snow or something else unusual occurs. Focusing on the vertical residuals, we calculate short and long-term RMS values for all stations and compare them with other QC parameters to separate healthy and well-behaved stations, healthy and nonlinear stations, and unhealthy, poorly-behaved stations. We also showcase examples of low-QC and other unusual episodes in the network.

  15. Experimental and numerical study of the wave run-up along a vertical plate

    DEFF Research Database (Denmark)

    Molin, Bernard; Kimmoun, O.; Liu, Y.

    2010-01-01

    , strong deviations from the predictions of linear theory gradually take place as the reflected wave field develops in the basin. This phenomenon is attributed to third-order interactions between the incoming and reflected wave systems, on the weather side of the plate. The measured profiles along...... the plate are compared with the predictions of two numerical models: an approximate model based on the tertiary interaction theory of Longuet-Higgins & Phillips (J. Fluid Mech., vol. 12, 1962, p. 333) for plane waves, which provides a steady-state solution, and a fully nonlinear numerical wavetank based......Results from experiments on wave interaction with a rigid vertical plate are reported. The 5m long plate is set against the wall of a 30m wide basin, at 100m from the wavemaker. This set-up is equivalent to a 10m plate in the middle of a 60m wide basin. Regular waves are produced, with wavelengths...

  16. Analysis of absorbed energy and efficiency of a solar flat plate collector

    Directory of Open Access Journals (Sweden)

    Anderson Miguel Lenz

    2017-07-01

    Full Text Available The highest percentage in home electricity demands in Brazil lies with the water heating systems, where the electric shower has a great contribution in consumption. The use of solar thermal panels is an alternative to minimize the strain on the electrical system by heating water. Current study evaluates a water heating system built with materials commonly used in home constructions. The tested collector is a 1 m² flat plate. Experiments were conducted at the State University of Western Paraná (UNIOESTE, campus Cascavel, Paraná State, Brazil. Temperature data were collected by PT100 sensors and solar radiation was measured with a pyranometer, coupled to a CR-1000 datalogger, with readings and collection every 5 minutes for 1 year. Data collection and analysis showed that the system presented monthly efficiency ranging between 33.7 and 53.54%, and energy absorbed between 30.79 and 75.29 kWh m-².month. Results show the system is a good option for use in residential or rural water heating due to decrease in the electric bill.

  17. EVALUATION OF FLAT-PLATE PHOTOVOLTAIC THERMAL HYBRID SYSTEMS FOR SOLAR ENERGY UTILIZATION.

    Energy Technology Data Exchange (ETDEWEB)

    ANDREWS,J.W.

    1981-06-01

    The technical and economic attractiveness of combined photovoltaic/thermal (PV/T) solar energy collectors was evaluated. The study was limited to flat-plate collectors since concentrating photovoltaic collectors require active cooling and thus are inherently PV/T collectors, the only decision being whether to use the thermal energy or to dump it. it was also specified at the outset that reduction in required roof area was not to be used as an argument for combining the collection of thermal and electrical energy into one module. Three tests of economic viability were identified, all of which PV/T must pass if it is to be considered a promising alternative: PV/T must prove to be competitive with photovoltaic-only, thermal-only, and side-by-side photovoltaic-plus-thermal collectors and systems. These three tests were applied to systems using low-temperature (unglazed) collectors and to systems using medium-temperature (glazed) collectors in Los Angeles, New York, and Tampa. For photovoltaics, the 1986 DOE cost goals were assumed to have been realized, and for thermal energy collection two technologies were considered: a current technology based on metal and glass, and a future technology based on thin-film plastics. The study showed that for medium-temperature applications PV/T is not an attractive option in any of the locations studied. For low-temperature applications, PV/T appears to be marginally attractive.

  18. Effect of Glass Thickness on Performance of Flat Plate Solar Collectors for Fruits Drying

    Directory of Open Access Journals (Sweden)

    Ramadhani Bakari

    2014-01-01

    Full Text Available This study aimed at investigating the effect of thickness of glazing material on the performance of flat plate solar collectors. Performance of solar collector is affected by glaze transmittance, absorptance, and reflectance which results into major heat losses in the system. Four solar collector models with different glass thicknesses were designed, constructed, and experimentally tested for their performances. Collectors were both oriented to northsouth direction and tilted to an angle of 10° with the ground toward north direction. The area of each collector model was 0.72 m2 with a depth of 0.15 m. Low iron (extra clear glass of thicknesses 3 mm, 4 mm, 5 mm, and 6 mm was used as glazing materials. As a control, all collector performances were analysed and compared using a glass of 5 mm thickness and then with glass of different thickness. The results showed that change in glass thickness results into variation in collector efficiency. Collector with 4 mm glass thick gave the best efficiency of 35.4% compared to 27.8% for 6 mm glass thick. However, the use of glass of 4 mm thick needs precautions in handling and during placement to the collector to avoid extra costs due to breakage.

  19. Leading-edge vortex burst on a low-aspect-ratio rotating flat plate

    Science.gov (United States)

    Medina, Albert; Jones, Anya R.

    2016-08-01

    This study experimentally investigates the phenomenon of leading-edge-vortex burst on rotating flat plate wings. An aspect-ratio-2 wing was driven in pure rotation at a Reynolds number of Re=2500 . Of primary interest is the evolution of the leading-edge vortex along the wing span over a single-revolution wing stroke. Direct force measurements of the lift produced by the wing revealed a single global lift maximum relatively early in the wing stroke. Stereoscopic particle image velocimetry was applied to several chordwise planes to quantify the structure and strength of the leading-edge vortex and its effect on lift production. This analysis revealed opposite-sign vorticity entrainment into the core of the leading-edge vortex, originating from a layer of secondary vorticity along the wing surface. Coincident with the lift peak, there emerged both a concentration of opposite vorticity in the leading-edge-vortex core, as well as axial flow stagnation within the leading-edge-vortex core. Planar control volume analysis was performed at the midspan to quantify the contributions of vorticity transport mechanisms to the leading-edge-vortex circulation. The rate of circulation annihilation by opposite-signed vorticity entrainment was found to be minimal during peak lift production, where convection balanced the flux of vorticity resulting in stagnation and eventually reversal of axial flow. Finally, vortex burst was found to be correlated with swirl number, where bursting occurs at a swirl threshold of Sw<0.6 .

  20. Reaction engineering analysis of Scenedesmus ovalternus in a flat-plate gas-lift photobioreactor.

    Science.gov (United States)

    Koller, Anja Pia; Wolf, Lara; Weuster-Botz, Dirk

    2017-02-01

    Microalgal strains of the genus Scenedesmus are a promising resource for commercial biotechnological applications. The temperature-, pH- and light-dependent growth of Scenedesmus ovalternus has been investigated on a laboratory scale. Best batch process performance was obtained at 30°C, pH 8.0 and an incident photon flux density of 1300μmolphotonsm-2s-1 using a flat-plate gas-lift photobioreactor. Highest growth rate (0.11h-1) and space-time yield (1.7±0.1gCDWL-1d-1) were observed when applying these reaction conditions. Biomass concentrations of up to 7.5±0.1gCDWL-1 were achieved within six days (25.0±0.5gCDWm-2d-1). The light-dependent growth kinetics of S. ovalternus was identified using Schuster's light transfer model and Andrews' light inhibition model (KS=545μmolphotonsm-2s-1; KI=2744μmolphotonsm-2s-1; μmax=0.21h-1). The optimal mean integral photon flux density for growth of S. ovalternus was estimated to be 1223μmolphotonsm-2s-1. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Experimental investigation of a large aspect ratio flat plate encountering a steam-wise gust

    Science.gov (United States)

    Mulleners, Karen; Mancini, Peter; Jones, Anya

    2015-11-01

    While humans are capable of mimicking, and even outperform, the kinematic capabilities of natural flyers, birds and insects are still way ahead of us when it comes to anticipating and dealing with turbulent and gusty flow conditions. To tailor and improve flight control capabilities of low Reynolds number flyers in real weather, we need to bridge this gap of knowledge. As a first step, we experimentally studied the aerodynamic influence of a simplified stream-wise gust on a large aspect ratio flat plate. The experiments were conduction in the 7 × 1 . 5 × 1 m3 towing tank at UMD which was equipped with a 4-axis computer-controlled motion system. The effect of a stream-wise gust was simulated by accelerating or decelerating the wing to a new constant velocity after an initial constant surge. A high-speed camera and light sheet optics were attached to the tow carriage allowing for time-resolved particle image velocimetry along the entire motion in addition to direct force measurements. A proper orthogonal decomposition of the flow field was carried out to study the time scales related to changes induced by the sudden acceleration or deceleration in addition to analyzing the size, position and trajectory of prominent vortices and associated forces during the gust encounter.

  2. Crust behavior in simultaneous melting and freezing on a submerged flat plate

    Energy Technology Data Exchange (ETDEWEB)

    Ganguli, A.; Bankoff, S.G.

    1978-12-01

    A theoretical and experimental investigation of the solidification of a flowing liquid onto a melting wall was carried out. In particular, the experimental work involved open channel laminar flow of water over a flat plate of n-decane. The point of interest is the dynamic behavior of the solidified crust, which forms a leading edge by melting. The motion of this leading edge was determined as a function of the water temperature, velocity, decane temperature and outlet weir height. This melting rate was found to be very sensitive to the water temperature and less dependent upon the other parameters. An approximate numerical method, using polynomial temperature profiles with time dependent coefficients, was used to solve the one-dimensional heat conduction model. From this, the dynamic behavior of the crust was predicted as a function of the experimental parameters and the local heat transfer coefficient on the freezing surface, which was later estimated. There is reasonable agreement between the predicted and experimentally observed motions of the leading edge.

  3. Two-dimensional scanner apparatus. [flaw detector in small flat plates

    Science.gov (United States)

    Kurtz, G. W.; Bankston, B. F. (Inventor)

    1984-01-01

    An X-Y scanner utilizes an eddy current or ultrasonic current test probe to detect surface defects in small flat plates and the like. The apparatus includes a scanner which travels on a pair of slide tubes in the X-direction. The scanner, carried on a carriage which slides in the Y-direction, is driven by a helix shaft with a closed-loop helix groove in which a follower pin carried by scanner rides. The carriage is moved incrementally in the Y-direction upon the completion of travel of the scanner back and forth in the X-direction by means of an indexing actuator and an indexing gear. The actuator is in the form of a ratchet which engages ratchet gear upon return of the scanner to the indexing position. The indexing gear is rotated a predetermined increment along a crack gear to move carriage incrementally in the Y-direction. Thus, simplified highly responsive mechanical motion may be had in a small lightweight portable unit for accurate scanning of small area.

  4. Flat-plate solar array project. Volume 8: Project analysis and integration

    Science.gov (United States)

    Mcguire, P.; Henry, P.

    1986-01-01

    Project Analysis and Integration (PA&I) performed planning and integration activities to support management of the various Flat-Plate Solar Array (FSA) Project R&D activities. Technical and economic goals were established by PA&I for each R&D task within the project to coordinate the thrust toward the National Photovoltaic Program goals. A sophisticated computer modeling capability was developed to assess technical progress toward meeting the economic goals. These models included a manufacturing facility simulation, a photovoltaic power station simulation and a decision aid model incorporating uncertainty. This family of analysis tools was used to track the progress of the technology and to explore the effects of alternative technical paths. Numerous studies conducted by PA&I signaled the achievement of milestones or were the foundation of major FSA project and national program decisions. The most important PA&I activities during the project history are summarized. The PA&I planning function is discussed and how it relates to project direction and important analytical models developed by PA&I for its analytical and assessment activities are reviewed.

  5. Design optimization of sinusoidal glass honeycomb for flat plate solar collectors

    Science.gov (United States)

    Mcmurrin, J. C.; Buchberg, H.

    1980-01-01

    The design of honeycomb made of sinusoidally corrugated glass strips was optimized for use in water-cooled, single-glazed flat plate solar collectors with non-selective black absorbers. Cell diameter (d), cell height (L), and pitch/diameter ratio (P/d) maximizing solar collector performance and cost effectiveness for given cell wall thickness (t sub w) and optical properties of glass were determined from radiative and convective honeycomb characteristics and collector performance all calculated with experimentally validated algorithms. Relative lifetime values were estimated from present materials costs and postulated production methods for corrugated glass honeycomb cover assemblies. A honeycomb with P/d = 1.05, d = 17.4 mm, L = 146 mm and t sub w = 0.15 mm would provide near-optimal performance over the range delta T sub C greater than or equal to 0 C and less than or equal to 80 C and be superior in performance and cost effectiveness to a non-honeycomb collector with a 0.92/0.12 selective black absorber.

  6. Boundary Layer of Photon Absorption Applied to Heterogeneous Photocatalytic Solar Flat Plate Reactor Design

    Directory of Open Access Journals (Sweden)

    Héctor L. Otálvaro-Marín

    2014-01-01

    Full Text Available This study provides information to design heterogeneous photocatalytic solar reactors with flat plate geometry used in treatment of effluents and conversion of biomass to hydrogen. The concept of boundary layer of photon absorption taking into account the efficient absorption of radiant energy was introduced; this concept can be understood as the reactor thickness measured from the irradiated surface where 99% of total energy is absorbed. Its thickness and the volumetric rate of photons absorption (VRPA were used as design parameters to determine (i reactor thickness, (ii maximum absorbed radiant energy, and (iii the optimal catalyst concentration. Six different commercial brands of titanium dioxide were studied: Evonik-Degussa P-25, Aldrich, Merck, Hombikat, Fluka, and Fisher. The local volumetric rate of photon absorption (LVRPA inside the reactor was described using six-flux absorption-scattering model (SFM applied to solar radiation. The radiation field and the boundary layer thickness of photon absorption were simulated with absorption and dispersion effects of catalysts in water at different catalyst loadings. The relationship between catalyst loading and reactor thickness that maximizes the absorption of radiant energy was obtained for each catalyst by apparent optical thickness. The optimum concentration of photocatalyst Degussa P-25 was 0.2 g/l in 0.86 cm of thickness, and for photocatalyst Aldrich it was 0.3 g/l in 0.80 cm of thickness.

  7. Enhancement of microalgae production by embedding hollow light guides to a flat-plate photobioreactor.

    Science.gov (United States)

    Sun, Yahui; Huang, Yun; Liao, Qiang; Fu, Qian; Zhu, Xun

    2016-05-01

    To offset the adverse effects of light attenuation on microalgae growth, hollow polymethyl methacrylate (PMMA) tubes were embedded into a flat-plate photobioreactor (PBR) as light guides. In this way, a fraction of incident light could be transmitted and emitted to the interior of the PBR, providing a secondary light source for cells in light-deficient regions. The average light intensity of interior regions 3-6cm from surfaces with 70μmolm(-2)s(-1) incident light was enhanced 2-6.5 times after 3.5days cultivation, resulting in a 23.42% increase in biomass production to that cultivated in PBR without PMMA tubes. The photosynthetic efficiency of microalgae in the proposed PBR was increased to 12.52%. Moreover, the installation of hollow PMMA tubes induced turbulent flow in the microalgae suspension, promoting microalgae suspension mixing. However, the enhanced biomass production was mainly attributed to the optimized light distribution in the PBR. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Production of Fatty Acids and Protein by Nannochloropsis in Flat-Plate Photobioreactors.

    Science.gov (United States)

    Hulatt, Chris J; Wijffels, René H; Bolla, Sylvie; Kiron, Viswanath

    2017-01-01

    Nannochloropsis is an industrially-promising microalga that may be cultivated for alternative sources of nutrition due to its high productivity, protein content and lipid composition. We studied the growth and biochemical profile of Nannochloropsis 211/78 (CCAP) in optimized flat-plate photobioreactors. Eighteen cultivations were performed at two nutrient concentrations. The fatty acid, protein content and calorific values were analyzed after 8, 12 and 16 days. Neutral lipids were separated and the changes in fatty acids in triglycerides (TAGs) during nutrient depletion were recorded. The maximum cell density reached 4.7 g∙L-1 and the maximum productivity was 0.51 g∙L-1∙d-1. During nutrient-replete conditions, eicosapentaneoic acid (EPA) and total protein concentrations measured 4.2-4.9% and 50-55% of the dry mass, respectively. Nutrient starvation induced the accumulation of fatty acids up to 28.3% of the cell dry weight, largely due to the incorporation of C16:0 and C16:1n-7 fatty acyl chains into neutral lipids. During nutrient starvation the total EPA content did not detectibly change, but up to 37% was transferred from polar membrane lipids to the neutral lipid fraction.

  9. Production of Fatty Acids and Protein by Nannochloropsis in Flat-Plate Photobioreactors.

    Directory of Open Access Journals (Sweden)

    Chris J Hulatt

    Full Text Available Nannochloropsis is an industrially-promising microalga that may be cultivated for alternative sources of nutrition due to its high productivity, protein content and lipid composition. We studied the growth and biochemical profile of Nannochloropsis 211/78 (CCAP in optimized flat-plate photobioreactors. Eighteen cultivations were performed at two nutrient concentrations. The fatty acid, protein content and calorific values were analyzed after 8, 12 and 16 days. Neutral lipids were separated and the changes in fatty acids in triglycerides (TAGs during nutrient depletion were recorded. The maximum cell density reached 4.7 g∙L-1 and the maximum productivity was 0.51 g∙L-1∙d-1. During nutrient-replete conditions, eicosapentaneoic acid (EPA and total protein concentrations measured 4.2-4.9% and 50-55% of the dry mass, respectively. Nutrient starvation induced the accumulation of fatty acids up to 28.3% of the cell dry weight, largely due to the incorporation of C16:0 and C16:1n-7 fatty acyl chains into neutral lipids. During nutrient starvation the total EPA content did not detectibly change, but up to 37% was transferred from polar membrane lipids to the neutral lipid fraction.

  10. A Dynamic Multinode Model for Component-Oriented Thermal Analysis of Flat-Plate Solar Collectors

    Directory of Open Access Journals (Sweden)

    Christoph N. Reiter

    2015-01-01

    Full Text Available A mathematical model of a flat-plate solar collector was developed on the basis of the physical principles of optics and heat transfer in order to determine collector’s component temperatures as well as collector efficiency. In contrast to many available models, the targeted use of this dynamic model is the detailed, theoretical investigation of the thermal behaviour of newly developed or adjusted collector designs on component level, for example, absorber, casing, or transparent cover. The defined model is based on a multinode network (absorber, fluid, glazing, and backside insulation containing the relevant physical equations to transfer the energy. The heat transfer network covers heat conduction, convection, and radiation. Furthermore, the collector optics is defined for the plane glazing and the absorber surface and also considers interactions between them. The model enables the variation of physical properties considering the geometric parameters and materials. Finally, the model was validated using measurement data and existing efficiency curve models. Both comparisons proved high accuracy of the developed model with deviation of up to 3% in collector efficiency and 1 K in component temperatures.

  11. Hydrogen production by Rhodobacter sphaeroides O.U.001 in a flat plate solar bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Eroglu, Inci; Tabanoglu, Altan; Eroglu, Ela [Department of Chemical Engineering, Middle East Technical University, 06531 Ankara (Turkey); Guenduez, Ufuk; Yuecel, Meral [Department of Biology, Middle East Technical University, 06531 Ankara (Turkey)

    2008-01-15

    Rhodobacter sphaeroides O.U.001 can produce hydrogen under anaerobic conditions and illumination. The objective of this study was to investigate the performance of an 8 l flat plate solar bioreactor operating in outdoor conditions. Different organic acids were used as carbon sources (malate, lactate and acetate) and olive mill waste water was used as a sole substrate source. The consumption and the production of the organic acids were determined by HPLC. The accumulation of by-products, such as poly-{beta}-hydroxybutyrate (PHB) and carotenoid, throughout the course of hydrogen production was determined. The hydrogen production rate was highest (0.01 l/l/h) when malate was the carbon source. Formate was observed as the fermentation end product. Acetate resulted in low hydrogen gas production and high PHB accumulation. When acetate was used as the carbon source, butyrate was produced as a result of fermentation. Promising amounts of PHB and caretenoid were accumulated during hydrogen production from diluted olive mill wastewater. (author)

  12. Heat transfer in a low latitude flat-plate solar collector

    Directory of Open Access Journals (Sweden)

    Oko C.O.C.

    2012-01-01

    Full Text Available Study of rate of heat transfer in a flat-plate solar collector is the main subject of this paper. Measurements of collector and working fluid temperatures were carried out for one year covering the harmattan and rainy seasons in Port Harcourt, Nigeria, which is situated at the latitude of 4.858oN and longitude of 8.372oE. Energy balance equations for heat exchanger were employed to develop a mathematical model which relates the working fluid temperature with the vital collector geometric and physical design parameters. The exit fluid temperature was used to compute the rate of heat transfer to the working fluid and the efficiency of the transfer. The optimum fluid temperatures obtained for the harmattan, rainy and yearly (or combined seasons were: 317.4, 314.9 and 316.2 [K], respectively. The corresponding insolation utilized were: 83.23, 76.61 and 79.92 [W/m2], respectively, with the corresponding mean collector efficiency of 0.190, 0.205 and 0.197 [-], respectively. The working fluid flowrate, the collector length and the range of time that gave rise to maximum results were: 0.0093 [kg/s], 2.0 [m] and 12PM - 13.00PM, respectively. There was good agreement between the computed and the measured working fluid temperatures. The results obtained are useful for the optimal design of the solar collector and its operations.

  13. Design of 3-D Nacelle near Flat-Plate Wing Using Multiblock Sensitivity Analysis (ADOS)

    Science.gov (United States)

    Eleshaky, Mohamed E.; Baysal, Oktay

    1994-01-01

    One of the major design tasks involved in reducing aircraft drag is the integration of the engine nacelles and airframe. With this impetus, nacelle shapes with and without the presence of a flat-plate wing nearby were optimized. This also served as a demonstration of the 3-D version of the recently developed aerodynamic design optimization methodology using sensitivity analysis, ADOS. The required flow analyses were obtained by solving the three-dimensional, compressible, thin-layer Navier-Stokes equations using an implicit, upwind-biased, finite volume scheme. The sensitivity analyses were performed using the preconditioned version of the SADD scheme (sensitivity analysis on domain decomposition). In addition to demonstrating the present method's capability for automatic optimization, the results offered some insight into two important issues related to optimizing the shapes of multicomponent configurations in close proximity. First, inclusion of the mutual interference between the components resulted in a different shape as opposed to shaping an isolated component. Secondly, exclusion of the viscous effects compromised not only the flow physics but also the optimized shapes even for isolated components.

  14. Effects of Unsteady Flow Past An Infinite Vertical Plate With Variable ...

    African Journals Online (AJOL)

    The effects of unsteady flow past an infinite vertical plate with variable temperature and constant mass flux are investigated. Laplace transform technique is used to obtain velocity and concentration fields. The computation of the results indicates that the velocity profiles increase with increase in Grashof numbers, mass ...

  15. Mixed convective heat transfer from a vertical plate embedded in a ...

    Indian Academy of Sciences (India)

    Home; Journals; Sadhana; Volume 40; Issue 2. Mixed convective heat transfer from a vertical plate embedded in a saturated non-Darcy porous medium with concentration and melting effect. K Hemalatha Peri K Kameswaran M V D N S Madhavi. Mechanical Sciences Volume 40 Issue 2 April 2015 pp 455-465 ...

  16. Free surface entropic lattice Boltzmann simulations of film condensation on vertical hydrophilic plates

    DEFF Research Database (Denmark)

    Hygum, Morten Arnfeldt; Karlin, Iliya; Popok, Vladimir

    2015-01-01

    A model for vapor condensation on vertical hydrophilic surfaces is developed using the entropic lattice Boltzmann method extended with a free surface formulation of the evaporation–condensation problem. The model is validated with the steady liquid film formation on a flat vertical wall....... It is shown that the model is in a good agreement with the classical Nusselt equations for the laminar flow regime. Comparisons of the present model with other empirical models also demonstrate good agreement beyond the laminar regime. This allows the film condensation modeling at high film Reynolds numbers...

  17. The structure of turbulent flow around vertical plates containing holes and attached to a channel bed

    Science.gov (United States)

    Basnet, K.; Constantinescu, G.

    2017-11-01

    High-resolution, 3-D large eddy simulations are conducted to study the physics of flow past 2-D solid and porous vertical plates of height H mounted on a horizontal surface (no bottom gap) with a fully developed, turbulent incoming flow. The porous plate consists of an array of spanwise-oriented, identical solid cylinders of rectangular cross section. The height of the solid cylinders and the spacing between the solid cylinders, corresponding to the plate's "holes," are kept constant for any given configuration, as the present study considers only plates of uniform porosity. The paper discusses how the mean flow and turbulence structure around the vertical plate, the unsteady forces acting on the plate, the dynamics of the large-scale turbulent eddies, the spectral content of the wake, and the distribution of the bed friction velocity on the horizontal channel bed vary as a function of the plate porosity (0% forming at the top of the plate and the wake structure. It is found that the main recirculation eddy in the wake remains attached to the plate for P forms away from the porous plate. The energy of the billows advected in the SSL decays monotonically with increasing plate porosity. For cases when the recirculation eddy remains attached to the plate, the larger billows advected in the downstream part of the SSL are partially reinjected inside the main recirculation eddy as a result of their interaction with the channel bed. This creates a feedback mechanism that induces large-scale disturbances of the spanwise-oriented vortex tubes advected inside the upstream part of the SSL. Results also show that the mean drag coefficient and the root-mean-square of the drag coefficient fluctuations increase mildly with increasing d/H. Meanwhile, varying d/H has a negligible effect on the position and size of the main recirculation eddy. The presence of large-scale roughness elements (2-D ribs) at the bed results in the decrease of the mean drag coefficient of the plate and

  18. Group method analysis of magneto-elastico-viscous flow along a semi-infinite flat plate with heat transfer

    Science.gov (United States)

    Helal, M. M.; Abd-El-Malek, M. B.

    2005-01-01

    The group theoretic method is applied for solving problem of the flow of an elastico-viscous liquid past an infinite flat plate in the presence of a magnetic field normal to the plate. The application of one-parameter transformation group reduces the number of independent variables, by one, and consequently the system of governing partial differential equations with boundary conditions reduces to a system of ordinary differential equations with appropriate corresponding conditions. Numerical solution of the velocity field and heat transfer have been obtained. The effect of the magnetic parameter M on velocity field, shear stress, temperature fields and heat transfer has been discussed.

  19. Radiation and chemical reaction effects on isothermal vertical oscillating plate with variable mass diffusion

    Directory of Open Access Journals (Sweden)

    Manivannan Kaliappan

    2009-01-01

    Full Text Available The unsteady flow of a viscous incompressible flow past an infinite isothermal vertical oscillating plate, in the presence of thermal radiation and homogeneous chemical reaction of first order has been studied. The fluid considered here is a gray, absorbing-emitting radiation but a non-scattering medium. The plate temperature is raised to Tw and the concentration level near the plate is raised linearly with respect to time. An exact solution to the dimensionless governing equations has been obtained by the Laplace transform method, when the plate is oscillating harmonically in its own plane. The effects of velocity, temperature, and concentration are studied for different physical parameters like phase angle, radiation parameter, chemical reaction parameter, Schmidt number, thermal Grashof number, mass Grashof number, and time are studied graphically. It is observed that the velocity increases with decreasing phase angle wt.

  20. Design, Construction, and Performance Analysis of a Wood Thermal Conductivity Measurement Device using Flat Plate Heat Pipes

    Directory of Open Access Journals (Sweden)

    Rasouli Moien

    2011-12-01

    Full Text Available In this paper, the design, construction, and performance analysis of a wood thermal conductivity measurement device using flat plate heat pipes has been experimentally studied. The device was designed to measure the thermal conductivity of wood in various ranges of temperature. Thermal conductivity of hornbeam (Carpinus betulus has been measured at various temperatures between 40-80 ºC and a relationship has been recommended for the sample. The results show that the thermal conductivity of this species increases linearly with temperature. Also, it has been concluded that flat plate heat pipes distribute heat flux on the surface of the wood uniformly leading to a faster steady state condition, which can reduce time of the test and result in energy saving and more accurate results.

  1. Standard Test Method for Water Penetration of Flat Plate Solar Collectors by Uniform Static Air Pressure Difference

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1986-01-01

    1.1 This test method covers the determination of the resistance of flat plate solar collectors to water penetration when water is applied to their outer surfaces with a static air pressure at the outer surface higher than the pressure at the interior of the collector. 1.2 This test method is applicable to any flat plate solar collector. 1.3 The proper use of this test method requires a knowledge of the principles of pressure and deflection measurement. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary information is contained in Section 6.

  2. Experimental investigation of effect of jet decay rate on jet-induced pressures on a flat plate

    Science.gov (United States)

    Kuhlman, J. M.; Ousterhout, D. S.; Warcup, R. W.

    1978-01-01

    An experimental study of the interaction between a lift jet and an aircraft wing for a jet VTOL aircraft was performed for the simplified model of an unheated, subsonic, circular jet exiting at right angles to a flat plate into a uniform subsonic crosswind. The effects of jet dynamic pressure decay rate upon the jet location and jet induced pressure distribution on the plate were studied over a range of jet to crossflow velocity ratios of 2.2 or = R or = 10. Jet decay rate was varied through use of cylindrical centerbodies with flat or hemispherical tips submerged in the jet nozzle at various depths below the jet exit plane. Quicker jet dynamic pressure decay, caused by the presence of a centerbody, resulted in reductions in the jet induced lift loss by as much as 45 percent relative to values for jets with no centerbody. These reductions in lift loss were observed at the larger values of crossflow velocity.

  3. Aerodynamic optimization of the flat-plate leading edge for experimental studies of laminar and transitional boundary layers

    Science.gov (United States)

    Hanson, Ronald E.; Buckley, Howard P.; Lavoie, Philippe

    2012-10-01

    This work is concerned with the design of a leading edge for a flat-plate model used to study laminar and transitional boundary layers. For this study, the flow over the complete boundary-layer model, including leading edge, flat section, and trailing-edge flap, is modeled. The effect of important geometrical features of the leading edge on the resulting pressure distribution, starting from the well-known symmetric modified super ellipse, is investigated. A minimal pressure gradient on the measurement side of the plate is achieved using an asymmetrical configuration of modified super ellipses, with a thickness ratio of 7/24. An aerodynamic shape optimization is performed to obtain a novel leading edge shape that greatly reduces the length of the non-zero pressure gradient region and the adverse pressure gradient region compared to geometries defined by ellipses. Wind tunnel testing is used to validate the numerical solutions.

  4. Performance Analysis of a Shallow Duct Flat Plate Solar Air Heater with and without Porous Media

    Directory of Open Access Journals (Sweden)

    Haroun A.K. Shahad

    2016-12-01

    Full Text Available In this study a flat plate solar air heater with a shallow duct is analyzed experimentally. The collector consists of a 4.5m long air duct with a (20×5cm cross-sectional area. The air duct consists of four channels so that the collector becomes more compact. The collector is studied under the weather conditions of Hilla city – Iraq with latitude and longitude equal 32.3° N and 44.25° E respectively and it is tilted by 45° with the horizontal plane. The effect of the air mass flow rate on the collector performance is also studied.The performance of the collector is analyzed with and without porous media stuffing. The measured parameters are the air and absorber temperatures, air speed and pressure drop. The temperatures are measured by means of type (K thermocouples as this type covers the temperature range of the studied system. The values of the temperature are displayed by temperature data logger devices. The air speed and pressure drop are measured by digital anemometer and manometer devices respectively. The results of the studied system show that as the air mass flow rate increases, the temperature of both the flowing air and the absorber decrease, whilst the efficiency of the collector increases. The results also show that the addition of the steel wool porous material inside the air duct increases the temperature of both the flowing air and the absorber, and by that increases the efficiency of the collector. The porous media also caused an increase in the pressure drop between the outlet air and the atmosphere. This pressure drop increased with the increase in the air mass flow rate

  5. A bubble column evaporator with basic flat-plate condenser for brackish and seawater desalination.

    Science.gov (United States)

    Schmack, Mario; Ho, Goen; Anda, Martin

    2016-01-01

    This paper describes the development and experimental evaluation of a novel bubble column-based humidification-dehumidification system, for small-scale desalination of saline groundwater or seawater in remote regions. A bubble evaporator prototype was built and matched with a simple flat-plate type condenser for concept assessment. Consistent bubble evaporation rates of between 80 and 88 ml per hour were demonstrated. Particular focus was on the performance of the simple condenser prototype, manufactured from rectangular polyvinylchlorid plastic pipe and copper sheet, a material with a high thermal conductivity that quickly allows for conduction of the heat energy. Under laboratory conditions, a long narrow condenser model of 1500 mm length and 100 mm width achieved condensate recovery rates of around 73%, without the need for external cooling. The condenser prototype was assessed under a range of different physical conditions, that is, external water cooling, partial insulation and aspects of air circulation, via implementing an internal honeycomb screen structure. Estimated by extrapolation, an up-scaled bubble desalination system with a 1 m2 condenser may produce around 19 l of distilled water per day. Sodium chloride salt removal was found to be highly effective with condensate salt concentrations between 70 and 135 µS. Based on findings and with the intent to reduce material cost of the system, a shorter condenser length of 750 mm for the non-cooled (passive) condenser and of 500 mm for the water-cooled condenser was considered to be equally efficient as the experimentally evaluated prototype of 1500 mm length.

  6. An Experimental Study of Polymer Drag Reduction and Boundary Layer Diffusion Characteristics for Incompressible Flow Over a Flat Plate.

    Science.gov (United States)

    1979-08-15

    Macromolecular Solutions," Hendon College of Technology, London, 1966. ___, "Turbulence and Drag Reduction With Polymer Additives," Research Bulletin...no. 4, Hendon College of Technology, London, January 1967. White, F. N., "An Analysis of Flat-Plate Drag With Polymer Additives," Journal of... Christoph , G. H., "A Simple Theory for the Two-Diensional Compressible Turbulent Boundary Layer," Transactions of the ASHE, September 1972. White, F. M

  7. The addition of red lead to flat plate and tubular valve regulated miners cap lamp lead-acid batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ferg, E.E.; Loyson, P. [Department of Chemistry, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Poorun, A. [Willard Batteries, P.O. Box 1844, Port Elizabeth 6000 (South Africa)

    2006-04-21

    The study looked at the use of red lead in the manufacturing of valve regulated lead acid (VRLA) miners cap lamp (MCL) batteries that were made with either flat plate or tubular positive electrodes. A problem with using only grey oxide in the manufacture of thick flat plate or tubular electrodes is the poor conversion of the active material to the desired lead dioxide. The addition of red lead to the initial starting material improves the formation efficiency but is considerably more expensive thereby increasing the cost of manufacturing. The study showed that by carefully controlling the formation conditions in terms of the voltage and temperature of a battery, good capacity performance can be achieved for cells made with flat plate electrodes that contain up to 25% red lead. The small amount of red lead in the active cured material reduces the effect of electrode surface sulphate formation and allows the battery to achieve its rated capacity within the first few cycles. Batteries made with flat plate positive electrodes that contained more that 50% red lead showed good initial capacity but had poor structural active material bonding. The study showed that MCL batteries made with tubular positive electrodes that contained less than 75% red lead resulted in a poorly formed electrode with limited capacity utilization. Pickling and soaking times of the tubular electrodes should be kept at a minimum thereby allowing higher active material utilization during subsequent capacity cycling. The study further showed that it is beneficial to use higher formation rates in order to reduce manufacturing time and to improve the active material characteristics. (author)

  8. New movable plate for efficient millimeter wave vertical on-chip antenna

    KAUST Repository

    Marnat, Loic

    2013-04-01

    A new movable plate concept is presented in this paper to realize mm-wave vertical on-chip antennas through MEMS based post-processing steps in a CMOS compatible process. By virtue of its vertical position, the antenna is isolated from the lossy Si substrate and hence performs with a better efficiency as compared to the horizontal position. In addition, the movable plate concept enables polarization diversity by providing both horizontal and vertical polarizations on the same chip. Through a first iteration fractal bowtie antenna design, dual band (60 and 77 GHz) operation is demonstrated in both horizontal and vertical positions without any change in dimensions or use of switches for two different mediums (Si and air). To support the movable plate concept, the transmission line and antenna are designed on a flexible polyamide, where the former has been optimized to operate in the bent position. The design is highly suitable for compact, low cost and efficient SoC solutions. © 1963-2012 IEEE.

  9. Particle deposition on face-up flat plates in parallel airflow under the combined influences of thermophoresis and electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Handol; Yook, Sejin; Han, Seogyoung [Hanyang University, Seoul (Korea, Republic of)

    2012-10-15

    The deposition velocity is used to assess the degree of particulate contamination of wafers or photomasks. A numerical model was developed to predict the deposition velocity under the combined influences of thermophoresis and electrophoresis. The deposition velocity onto a face-up flat plate in parallel airflow was simulated by varying the temperature difference between the plate's surface and ambient air or by changing the strength of the electric field established above the plate. Both attraction and repulsion by thermophoresis or electrophoresis were considered. When the plate's surface was colder than ambient air, the surface of the face-up plate could be at risk of contamination by charged particles even with a repulsive applied electric force. When the temperature of the plate's surface was higher than the ambient temperature, the degree of particulate contamination on the surface of the face-up plate could be remarkably reduced in the presence of an electric field. The effect of repulsive thermophoresis, however, is expected to be reduced for very fine particles of high electric mobility or for micrometer-sized particles with large gravitational settling speed when the charged particles are influenced by an attractive electric force.

  10. Effect of jet-mainstream velocity ratio on flow characteristics and heat transfer enhancement of jet on flat plate flow

    Science.gov (United States)

    Puzu, N.; Prasertsan, S.; Nuntadusit, C.

    2017-09-01

    The aim of this research was to study the effect of jet-mainstream velocity ratio on flow and heat transfer characteristics of jet on flat plate flow. The jet from pipe nozzle with inner diameter of D=14 mm was injected perpendicularly to mainstream on flat plate. The flat plate was blown by mainstream with uniform velocity profile at 10 m/s. The velocity ratio (jet to mainstream velociy) was varied at VR=0.25 and 3.5 by adjusting velocity of jet flow. For heat transfer measurement, a thin foil technique was used to evaluate the heat transfer coefficient by measuring temperature distributions on heat transfer surface with constant heat flux by using infrared camera. Flow characteristics were simulated by using a computational fluid dynamics (CFD) with commercial software ANSYS Fluent (Ver.15.0). The results showed that the enhancement of heat transfer along downstream direction for the case of VR=0.25 was from the effect of jet stream whereas for the case of VR=3.5 was from the effect of mainstream.

  11. Open Channel Natural Convection Heat Transfer on a Vertical Finned Plate

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joo Hyun; Heo, Jeong Hwan; Chung, Bum Jin [Kyung Hee Univ., Yongin (Korea, Republic of)

    2013-10-15

    The natural convection heat transfer of vertical plate fin was investigated experimentally. Heat transfer systems were replaced by mass-transfer systems, based on the analogy concept. The experimental results lie within the predictions of the existing heat transfer correlations of plate-fin for the natural convections. An overlapped thermal boundary layers caused increasing heat transfer, and an overlapped momentum boundary layers caused decreasing heat transfer. As the fin height increases, heat transfer was enhanced due to increased inflow from the open side of the fin spacing. When fin spacing and fin height are large, heat transfer was unaffected by the fin spacing and fin height. Passive cooling by natural convection becomes more and more important for the nuclear systems as the station black out really happened at the Fukushima NPPs. In the RCCS (Reactor Cavity Cooling System) of a VHTR (Very High Temperature Reactor), natural convection cooling through duct system is adopted. In response to the stack failure event, extra cooling capacity adopting the fin array has to be investigated. The finned plate increases the surface area and the heat transfer increases. However, the plate of fin arrays may increase the pressure drop and the heat transfer decreases. Therefore, in order to enhance the passive cooling with fin arrays, the parameters for the fin arrays should be optimized. According to Welling and Wooldridge, a natural convection on vertical plate fin is function of Gr, Pr, L, t, S, and H. The present work investigated the natural convection heat transfer of a vertical finned plate with varying the fin height and the fin spacing. In order achieve high Rayleigh numbers, an electroplating system was employed and the mass transfer rates were measured using a copper sulfate electroplating system based on the analogy concept.

  12. Natural convective magneto-nanofluid flow and radiative heat transfer past a moving vertical plate

    Directory of Open Access Journals (Sweden)

    S. Das

    2015-03-01

    Full Text Available An investigation of the hydromagnetic boundary layer flow past a moving vertical plate in nanofluids in the presence of a uniform transverse magnetic field and thermal radiation has been carried out. Three different types of water-based nanofluids containing copper, aluminum oxide and titanium dioxide are taken into consideration. The governing equations are solved using Laplace transform technique and the solutions are presented in closed form. The numerical values of nanofluid temperature, velocity, the rate of heat transfer and the shear stress at the plate are presented graphically for several values of the pertinent parameters. The present study finds applications in engineering devices.

  13. Flat plate approximation in the three-dimensional slamming; Heiban kinji ni yoru sanjigen suimen shogeki keisanho ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Toyama, Y. [Mitsui Engineering and Shipbuilding Co. Ltd., Tokyo (Japan)

    1996-12-31

    A slamming load generated by interactive motions between a ship body and water face is an important load in ensuring safety of the ship. A flat plate approximation developed by Wagner is used as a two-dimensional slamming theory, but it has a drawback in handling edges of a flat plate. Therefore, an attempt was made to expand the two-dimensional Wagner`s theory to three dimensions. This paper first shows a method to calculate water face slamming of an arbitrary axisymmetric body by using circular plate approximation. The paper then proposes a method to calculate slamming pressure distribution and slamming force for the case when shape of the water contacting surface may be approximated by an elliptic shape. Expansion to the three dimensions made clear to some extent the characteristics of the three-dimensional slamming. In the case of two dimensions or a circular column for example, the water contacting area increases rapidly in the initial stage generating large slamming force. However, in the case of three dimensions, since the water contacting area expands longitudinally and laterally, the slamming force tends to increase gradually. Maximum slamming pressure was found proportional to square of moving velocity in a water contacting boundary in the case of three dimensions, and similar to stagnation pressure on a gliding plate. 12 refs., 17 figs., 1 tab.

  14. Optimization of thermal performance of a smooth flat-plate solar air heater using teaching–learning-based optimization algorithm

    Directory of Open Access Journals (Sweden)

    R. Venkata Rao

    2015-12-01

    Full Text Available This paper presents the performance of teaching–learning-based optimization (TLBO algorithm to obtain the optimum set of design and operating parameters for a smooth flat plate solar air heater (SFPSAH. The TLBO algorithm is a recently proposed population-based algorithm, which simulates the teaching–learning process of the classroom. Maximization of thermal efficiency is considered as an objective function for the thermal performance of SFPSAH. The number of glass plates, irradiance, and the Reynolds number are considered as the design parameters and wind velocity, tilt angle, ambient temperature, and emissivity of the plate are considered as the operating parameters to obtain the thermal performance of the SFPSAH using the TLBO algorithm. The computational results have shown that the TLBO algorithm is better or competitive to other optimization algorithms recently reported in the literature for the considered problem.

  15. Prediction and measurement of heat transfer rates for the shock-induced unsteady laminar boundary layer on a flat plate

    Science.gov (United States)

    Cook, W. J.

    1972-01-01

    The unsteady laminar boundary layer induced by the flow-initiating shock wave passing over a flat plate mounted in a shock tube was theoretically and experimentally studied in terms of heat transfer rates to the plate for shock speeds ranging from 1.695 to 7.34 km/sec. The theory presented by Cook and Chapman for the shock-induced unsteady boundary layer on a plate is reviewed with emphasis on unsteady heat transfer. A method of measuring time-dependent heat-transfer rates using thin-film heat-flux gages and an associated data reduction technique are outlined in detail. Particular consideration is given to heat-flux measurement in short-duration ionized shocktube flows. Experimental unsteady plate heat transfer rates obtained in both air and nitrogen using thin-film heat-flux gages generally agree well with theoretical predictions. The experimental results indicate that the theory continues to predict the unsteady boundary layer behavior after the shock wave leaves the trailing edge of the plate even though the theory is strictly applicable only for the time interval in which the shock remains on the plate.

  16. Visualization study on the enhancement of heat transfer for the groove flat-plate heat pipe with nanoflower coated CuO layer

    Science.gov (United States)

    Xu, Pengfei; Li, Qiang

    2017-10-01

    A flat-plate heat pipe combining the groove structure and the nanoflower structure was developed to improve the wettability of the wick and enhance the phase change heat transfer. The flow and boiling phenomenon of the coolant inside the flat-plate heat pipe was experimentally observed and quantitatively analyzed by the visualization system. The experiment results indicated that the nanoflower coated groove flat-plate heat pipe, owning to its higher wetting area, larger boiling area, and more violent boiling behaviors, possessed a higher two phase heat transfer rate and larger equivalent thermal conductivity under high heat load conditions compared with the groove flat-plate heat pipe. Our work demonstrates a promising approach to address thermal management challenges for high heat flux electronic devices.

  17. MASS TRANSFER EFFECTS ON ACCELERATED VERTICAL PLATE IN A ROTATING FLUID WITH FIRST ORDER CHEMICAL REACTION

    Directory of Open Access Journals (Sweden)

    R. Muthucumaraswamy

    2012-12-01

    Full Text Available The precise analysis of the rotation effects on the unsteady flow of an incompressible fluid past a uniformly accelerated infinite vertical plate with variable temperature and mass diffusion has been undertaken, in the presence of a homogeneous first order chemical reaction. The dimensionless governing equations are solved using the Laplace-transform technique. The plate temperature as well as the concentration near the plate increase linearly with time. The velocity profiles, temperature and concentration are studied for different physical parameters, like the chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number and time. It is observed that the velocity increases with increasing values of thermal Grashof number or mass Grashof number. It is also observed that the velocity increases with decreasing rotation parameter Ω.

  18. Flat-Band Slow Light in a Photonic Crystal Slab Waveguide by Vertical Geometry Adjustment and Selective Infiltration of Optofluidics

    Science.gov (United States)

    Mansouri-Birjandi, Mohammad Ali; Janfaza, Morteza; Tavousi, Alireza

    2017-11-01

    In this paper, a photonic crystal slab waveguide (PhCSW) for slow light applications is presented. To obtain widest possible flat-bands of slow light regions—regions with large group index ( n g), and very low group velocity dispersion (GVD)—two core parameters of PhCSW structure are investigated. The design procedure is based on vertical shifting of the first row of the air holes adjacent to the waveguide center and concurrent selective optofluidic infiltration of the second row. The criteria of ± 10% variations is used for ease of definition and comparison of flat-band regions. By applying various geometry optimizations for the first row, our results suggest that a waveguide core of W 1.09 would provide a reasonable wide flat-band. Furthermore, infiltration of optofluidics in the second row alongside with geometry adjustments of the first row result in flexible control of 10 < n g < 32 and provide flat-band regions with large bandwidth (10 nm < Δ λ < 21.5 nm). Also, negligible GVD as low as β 2 = 10-24 (s2/m) is achieved. Numerical simulations are calculated by means of the three-dimensional plane wave expansion method.

  19. On the Behavior of Pliable Plate Dynamics in Wind: Application to Vertical Axis Wind Turbines

    Science.gov (United States)

    Cosse, Julia Theresa

    Numerous studies have shown that flexible materials improve resilience and durability of a structure. Several studies have investigated the behavior of elastic plates under the influence of a free stream, such as studies of the fluttering flag and others of shape reconfiguration, due to a free stream. The principle engineering contribution of this thesis is the design and development of a vertical axis wind turbine that features pliable blades which undergo various modes of behavior, ultimately leading to rotational propulsion of the turbine. The wind turbine design was tested in a wind tunnel and at the Caltech Laboratory for Optimized Wind Energy. Ultimately, the flexible blade vertical axis wind turbine proved to be an effective way of harnessing the power of the wind. In addition, this body of work builds on the current knowledge of elastic cantilever plates in a free stream flow by investigating the inverted flag. While previous studies have focused on the fluid structure interaction of a free stream on elastic cantilever plates, none had studied the plate configuration where the trailing edge was clamped, leaving the leading edge free to move. Furthermore, the studies presented in this thesis establish the geometric boundaries of where the large-amplitude flapping occurs.

  20. South-American plate advance and forced Andean trench retreat as drivers for transient flat subduction episodes.

    Science.gov (United States)

    Schepers, Gerben; van Hinsbergen, Douwe J J; Spakman, Wim; Kosters, Martha E; Boschman, Lydian M; McQuarrie, Nadine

    2017-05-16

    At two trench segments below the Andes, the Nazca Plate is subducting sub-horizontally over ∼200-300 km, thought to result from a combination of buoyant oceanic-plateau subduction and hydrodynamic mantle-wedge suction. Whether the actual conditions for both processes to work in concert existed is uncertain. Here we infer from a tectonic reconstruction of the Andes constructed in a mantle reference frame that the Nazca slab has retreated at ∼2 cm per year since ∼50 Ma. In the flat slab portions, no rollback has occurred since their formation at ∼12 Ma, generating 'horse-shoe' slab geometries. We propose that, in concert with other drivers, an overpressured sub-slab mantle supporting the weight of the slab in an advancing upper plate-motion setting can locally impede rollback and maintain flat slabs until slab tearing releases the overpressure. Tear subduction re-establishes a continuous slab and allows the process to recur, providing a mechanism for the transient character of flat slabs.

  1. Craft-Joule Project: Stagnation proof transparently insulated flat plate solar collector (static)

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, A; Cadafalch, J; Perez-Segarra, C.D. [Universitat Politecnica de Catalunya, Barcelona (Spain)] (and others)

    2000-07-01

    The STATIC (STAgnation proof Transparently Insulated flat plate Solar Collector) project is a Craft-Joule Project within the framework of the Non Nuclear Energy Programme Joule III coordinated by the Centre Technologic de Transferencia de Calor (CTTC). The core group of SMEs involved in the project has its main economical activity in the field of solar thermal systems at low temperature level (domestic hot water, solar heating, etc.). Beyond this, a large application potential exists for solar heating at medium temperature level (from 80 to 160 Celsius degrees) : industrial process heat, solar cooling and air conditioning, solar drying , distillation and desalination. Three of the four SME proposers are located in Southern Europe and in the Caribean, where a continuos increase of the demand for air conditioning and cooling has been demonstrated in the last years. The recent development of flat plate solar collectors with honeycomb-type transparent insulation cover has shown that this type of collectors can become a low cost alternative to evacuated tube and high concentrating CPC collectors in the medium temperature range from 80 to 160 Celsius degrees. With the expected reduction of collector cost, that forms 30%-50% of total system cost, a decisive break-through of solar thermal systems using heat in the medium temperature range can be achieved. The feasibility and good performance of these solar collectors has been proved in several prototypes. Nevertheless, up to now no commercial products are available. In order to reach this, the following developments of new concepts are necessary and are being carried out within this project: solution of the problem of overheating: development of collector versions for different working temperatures: optimization of the design with the support of high level numerical simulation. Several prototypes of the new solar collectors are being tested. System tests will also be carried or for two test arrays of optimized collector

  2. The forced convection flow over a flat plate with finite length with a constant convective boundary condition

    Energy Technology Data Exchange (ETDEWEB)

    Asterios, Pantokratoras [Democritus University of Thrace, Xanthi (Greece)

    2014-05-15

    The flow of a fluid past a flat plate of finite length and infinite width (two-dimensional flow) is considered. The plate is heated by convection from a fluid with constant temperature T{sub f}; with a constant heat transfer coefficient f{sub h} . In all previous works, the problem was considered using boundary layer theory whereas, in the present work, the solution is based on the full Navier-Stokes equations. The problem is investigated numerically with a finite volume method using the commercial code ANSYS FLUENT. The governing parameters are the Reynolds number, the new heat transfer parameter, and the Prandtl number. In addition, the influence of these three parameters on the temperature field is investigated. It is found that high Reynolds and high Prandtl numbers the wall temperature increases along the plate. They reach a maximum near the trailing edge then decrease. The same occurs as the heat transfer parameter increases. When the Reynolds and Prandtl numbers are low, the plate temperature tends to become symmetric, with a maximum at the middle of the plate. The temperature profiles become thicker as the Reynolds number and the Prandtl number is reduced while the temperature profiles become thicker as the heat transfer parameter increases.

  3. Blast response of centrally and eccentrically loaded flat-, U-, and V-shaped armored plates: comparative study

    Science.gov (United States)

    Trajkovski, J.; Kunc, R.; Prebil, I.

    2017-07-01

    Light armored vehicles (LAVs) can be exposed to blast loading by landmines or improvised explosive devices (IEDs) during their lifetime. The bottom hull of these vehicles is usually made of a few millimeters of thin armored plate that is the vehicle's weak point in a blast-loading scenario. Therefore, blast resistance and blast load redirection are very important characteristics in providing adequate vehicle as well as occupant protection. Furthermore, the eccentric nature of loading caused by landmines was found to be omitted in the studies of simplified structures like beams and plates. For this purpose, blast wave dispersion and blast response of centrally and eccentrically loaded flat-, U-, and V-shaped plates are examined using a combined finite-element-smoothed-particle hydrodynamics (FE-SPH) model. The results showed that V-shaped plates better disperse blast waves for any type of loading and, therefore, can be successfully applied in LAVs. Based on the results of the study and the geometry of a typical LAV 6× 6, the minimum angle of V-shaped plates is also determined.

  4. Vertical gradients for particulate Cu fractions in estuarine water over tidal flats

    NARCIS (Netherlands)

    Gerringa, L.J.A.; Hummel, H.; Moerdijk-Poortvliet, T.C.W.

    1999-01-01

    The speciation of particulate copper was determined at several depths (0, 5 and 15 cm above the sediment surface) in the water column above intertidal flat systems in the polluted estuary Westerschelde (WS) and the relatively un-polluted Oosterschelde sea-arm (OS), in order to assess differences in

  5. Mass transfer, fluid flow and membrane properties in flat and corrugated plate hyperfiltration modules

    NARCIS (Netherlands)

    Racz, I.G.; Groot Wassink, J.; Klaassen, R.

    1986-01-01

    Concentration polarisation, decreasing the efficiency in membrane separation processes, can be reduced by increasing mass transfer between membrane surface and bulk of the feed stream. Analogous to techniques used in plate heat exchangers efforts have been made to enhance mass transfer in a plate

  6. General Observations of the Time-Dependent Flow Field Around Flat Plates in Free Fall

    DEFF Research Database (Denmark)

    Hærvig, Jakob; Jensen, Anna Lyhne; Pedersen, Marie Cecilie

    2015-01-01

    a six degrees of freedom (6DOF) solver and a dynamic mesh. To validate the simulation, the trajectories of aluminium plates falling in water are recorded by digital camera recordings and compared to the simulation. The simulation is able to calculate the motion of the plate within each time step...

  7. PERFORMANCE DETERIORATION OF THERMOSIPHON SOLAR FLAT PLATE WATER HEATER DUE TO SCALING

    Directory of Open Access Journals (Sweden)

    arunachala umesh chandavar

    2011-12-01

    Full Text Available 0 0 1 340 1943 International Islamic University 16 4 2279 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Times New Roman";} The performance of Flat plate Solar Water Heater deteriorates within five to twelve years of their installation due to factors related to manufacturing, operating conditions, lack of maintenance etc. Especially, problem due to scaling is significant as it is based on quality of water used. The remaining factors are system dependent and could be overcome by quality production. Software is developed by incorporating Hottel Whillier Bliss (H-W-B equation to ascertain the effect of scaling on system efficiency in case of thermosiphon system. In case of clean thermosiphon system, the instantaneous efficiency calculated at 1000 W/m2 radiation is 72 % and it drops to 46 % for 3.7 mm scale thickness. The mass flow rate is reduced by 90 % for 3.7 mm scale thickness. Whereas, the average temperature drop of water in the tank is not critical due to considerable heat content in water under severe scaled condition.  But practically in case of major scale growth, some of the risers are likely to get blocked completely which leads to negligible temperature rise in the tank. ABSTRAK: Prestasi plat rata pemanas air suria merosot selepas lima hingga dua belas tahun  pemasangannya disebabkan faktor-faktor yang berkaitan dengan pembuatannya, cara kendaliannya, kurangnya penyelenggaraan dan sebagainya.  Terutama sekali, masalah disebabkan scaling (tembunan endapan mineral perlu diambil berat kerana ianya bergantung kepada kualiti air yang digunakan. Faktor-faktor selebihya bersandarkan sistem dan ia

  8. Experimental investigation of forced-convection in a finned rhombic tube of the flat-plate solar collectors

    DEFF Research Database (Denmark)

    Taherian, Hessam; Yazdanshenas, Eshagh

    2006-01-01

    Due to scarcity of literature on forced-convection heat transfer in a solar collector with rhombic cross-section absorbing tubes, a series of experiments was arranged and conducted to determine heat transfer coefficient. In this study, a typical rhombic cross-section finned tube of flat......-plate collectors used as the test section. Two correlations were proposed for the Nusselt number as a function of the Reynolds number and the Prandtl number based on hydraulic diameter for various heat fluxes. The temperature distribution along the finned tube for the fluid and the wall were also illustrated....

  9. Increasing Efficiency of a 33 MW OTEC in Indonesia Using Flat-plate Solar Collector for the Seawater Heater

    OpenAIRE

    Setiawan, Iwan Rohman; Purnama, Irwan; Halim, Abdul

    2017-01-01

    This paper presents a design concept of Ocean Thermal Energy Conversion (OTEC) plant built in Mamuju, West Sulawesi, with 33 MWe and 7.1% of the power capacity and efficiency, respectively. The generated electrical power and the efficiency of OTEC plant are enhanced by a simulation of a number of derived formulas. Enhancement of efficiency is performed by increasing the temperature of the warm seawater toward the evaporator from 26˚C up to 33.5˚C using a flat-plate solar collector. The simula...

  10. Boundary Layer Flow and Heat Transfer with Variable Fluid Properties on a Moving Flat Plate in a Parallel Free Stream

    Directory of Open Access Journals (Sweden)

    Norfifah Bachok

    2012-01-01

    Full Text Available The steady boundary layer flow and heat transfer of a viscous fluid on a moving flat plate in a parallel free stream with variable fluid properties are studied. Two special cases, namely, constant fluid properties and variable fluid viscosity, are considered. The transformed boundary layer equations are solved numerically by a finite-difference scheme known as Keller-box method. Numerical results for the flow and the thermal fields for both cases are obtained for various values of the free stream parameter and the Prandtl number. It is found that dual solutions exist for both cases when the fluid and the plate move in the opposite directions. Moreover, fluid with constant properties shows drag reduction characteristics compared to fluid with variable viscosity.

  11. A study on the effect of flat plate friction resistance on speed performance prediction of full scale

    Directory of Open Access Journals (Sweden)

    Park Dong-Woo

    2015-01-01

    Full Text Available Flat plate friction lines hare been used in the process to estimate speed performance of full-scale ships in model tests. The results of the previous studies showed considerable differences in determining form factors depending on changes in plate friction lines and Reynolds numbers. These differences had a great influence on estimation of speed performance of full-scale ships. This study- was conducted in two parts. In the first part, the scale effect of the form factor depending on change in the Reynolds number was studied based on CFD, in connection with three kinds of friction resistance curves: the ITTC-1957, the curve proposed by Grigson (1993; 1996, and the curve developed by Katsui et al (2005. In the second part, change in the form factor by three kinds of

  12. Heat transfer analysis in a Maxwell fluid over an oscillating vertical plate using fractional Caputo-Fabrizio derivatives

    Science.gov (United States)

    Khan, Ilyas; Ali Shah, Nehad; Mahsud, Yasir; Vieru, Dumitru

    2017-04-01

    This article is focused on heat transfer analysis in the unsteady flow of a generalized Maxwell fluid over an oscillating vertical flat plate with constant temperature. The well-known equation of the Maxwell fluid with classical derivatives, describing the unidirectional and one-dimensional flow, has been generalized to a non-integer-order derivative, known as fractional derivative, with free convection term of buoyancy. A new definition of the fractional derivative introduced by Caputo and Fabrizio has been used in the mathematical formulation of the problem. Exact solution of the dimensionless problem has been obtained by using the Laplace transform. These solutions are expressed with complementary error and modified Bessel functions. Similar solutions for classical Maxwell and Newtonian fluids and generalized Newtonian fluid performing the same motion are obtained as limiting cases of our general results. Graphical illustrations show that the velocity profiles corresponding to a generalized Maxwell fluid are similar to those for an ordinary Maxwell fluid when the fraction order approaches 1. A comparison amongst four different types of fluids is also shown graphically.

  13. Trans-iliosacral plating for vertically unstable fractures of sacral spine associated with spinopelvic dissociation: A cadaveric study

    Directory of Open Access Journals (Sweden)

    Pravin Padalkar

    2012-01-01

    Conclusions: Trans-iliosacral plating is feasible anatomically, biomechanically and radiologically for sacral fractures associated with vertical shear pelvic fractures. Low profile of plate reduces the risk of hardware prominence and decreases the need for implant removal. Also, the fixation pattern of plate allows to spare mobile lumbosacral junction which is an important segment for spinal mobility. Biomechanical studies revealed that rigidity offered by plate for cross headed displacement across fracture site is equal to sacroiliac screws and further rigidity of construct can be increased with addition of one more screw. There is need for precountered thicker plate in future.

  14. Evaluation of flat, angled, and vertical computer mice and their effects on wrist posture, pointing performance, and preference.

    Science.gov (United States)

    Odell, Dan; Johnson, Peter

    2015-01-01

    Modern computer users use the mouse almost three times as much as the keyboard. As exposure rates are high, improving upper extremity posture while using a computer mouse is desirable due to the fact that posture is one risk factor for injury. Previous studies have found posture benefits associated with using alternative mouse designs, but at the cost of performance and preference. To develop new computer mouse shapes, evaluate them versus benchmarks, and determine whether there are differences in wrist posture, pointing performance, and subjective measures. Three concept mice were designed and evaluated relative to two existing benchmark models: a traditional flat mouse, and an alternative upright mouse. Using a repeated measures design, twelve subjects performed a standardized point-and-click task with each mouse. Pointing performance and wrist posture was measured, along with perceived fatigue ratings and subjective preferences pre and post use. All of the concept mice were shown to reduce forearm pronation relative to the traditional flat mouse. There were no differences in pointing performance between the traditional flat mouse and the concept mice. In contrast, the fully vertical mouse reduced pronation but had the poorest pointing performance. Perceived fatigue and subjective preferences were consistently better for one concept mouse. Increasing mouse height and angling the mouse topcase can improve wrist posture without negatively affecting performance.

  15. Ice Forces on Flat, Vertical Indentors Pushed through Floating Ice Sheets

    Science.gov (United States)

    1990-05-01

    calculated dinal direction of the basin, and was powered by a motor according to the theory of an infinite plate on an elastic located at one end of...Radial crack Microcracking and AE signals As mentioned in the previous section, one (or some- Figue Figure scords oftheAEsignalsand the ice times two...Regions Science and Technology, 6: theory of indentation of ice plates. JournalofGlaciology, 99-104. 19(81): 285-300. Sodhi, D.S. and C.E. Morris (1984

  16. Fire characterization and object thermal response for a large flat plate adjacent to a large JP-4 fuel fire

    Energy Technology Data Exchange (ETDEWEB)

    Gritzo, L.A.; Moya, J.L. [Sandia National Labs, Albuquerque, NM (United States); Murray, D. [Naval Air Warefare Center, China Lake, CA (United States)

    1997-01-01

    A series of three 18.9 m diameter JP-4 pool fire experiments with a large (2.1 m X 4.6 m), flat plate calorimeter adjacent to the fuel pool were recently performed. The objectives of these experiments were to: (1) gain a better understanding of fire phenomenology, (2) provide empirical input parameter estimates for simplified, deterministic Risk Assessment Compatible Fire Models (RACFMs), (3) assist in continuing fire field model code validation and development, and (4) enhance the data base of fire temperature and heat flux to object distributions. Due to different wind conditions during each experiment, data were obtained for conditions where the plate was not engulfed, fully-engulfed and partially engulfed by the continuous flame zone. Results include the heat flux distribution to the plate and flame thermocouple temperatures in the vicinity of the plate and at two cross sections within the lower region of the continuous flame zone. The results emphasize the importance of radiative coupling (i.e. the cooling of the flames by a thermally massive object) and convective coupling (including object-induced turbulence and object/wind/flame interactions) in determining the heat flux from a fire to an object. The formation of a secondary flame zone on an object adjacent to a fire via convective coupling (which increases the heat flux by a factor of two) is shown to be possible when the object is located within a distance equal to the object width from the fire.

  17. Heat transfer in flow past a continuously moving porous flat plate with heat flux

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, T.V.R.; Sarma, Y.V.B.

    The analysis of the heat transfer in flow past a continuously moving semi-infinite plate in the presence of suction/ injection with heat flux has been presented. Similarity solutions have been derived and the resulting equations are integrated...

  18. An Experimental and Analytical Study of a Radiative Cooling System with Unglazed Flat Plate Collectors

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham; Taherian, Hessam

    2012-01-01

    On an average about 40% of world energy is used in residential buildings and the largest energy consumption is allocated to the cooling and air-conditioning systems. So every attempt to economize energy consumption is very valuable. In this research a nocturnal radiative cooling system with flat...

  19. Boundary layer flow of micropolar fluids past an impulsively started infinite vertical plate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Youn-Jea [School of Mechanical Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Suwon 440-746 (Korea, Republic of); Kim, Kwang-Su [SKKU Advanced Institute of Nano Technology, Sungkyunkwan University, 300 Cheoncheon-dong, Suwon 440-746 (Korea, Republic of)

    2007-02-15

    Transient free convective boundary layer flow of micropolar fluids past an impulsively started infinite vertical plate is investigated. The transformed dimensionless governing equations for the flow, microrotation and heat transfer characteristics are solved by using the Laplace transform technique. In particular, the relevant solution of the coupled governing equations was found with the second kind of the Volterra integral equation. The obtained results concerning velocity, microrotation and temperature across the boundary layer are illustrated graphically for different values of the parameters entering into the problem under consideration and the dependence of the flow and temperature fields from these parameters is discussed.

  20. Thermal diffusion effects on free convection and mass transfer flow for an infinite vertical plate

    CERN Document Server

    Abdel-Khalek, M M

    2003-01-01

    A theoretical study is performed to examine the effects of thermal diffusion on free convection and mass transfer flow for an infinite vertical plate. The governing equations for the fluid flow and the heat transfer are solved subject to the relevant boundary conditions. A perturbation technique is used to obtain expressions for the velocity field and skin friction. An analysis of the effects of the parameters on the concentration, velocity and temperature profiles as well as skin friction and the rate of mass and heat transfer is done with the aid of graphs.

  1. Gravitational attraction of a vertical pyramid model of flat top-and ...

    Indian Academy of Sciences (India)

    Here, we propose a vertical pyramid model with depth-wise parabolic density contrast variation. Initially, we validate our analytic expression against the gravity effect of a right rectangular parallelepiped of constant density contrast. We provide two synthetic examples and a case study for illustrating the effectiveness of our ...

  2. Small-Scale Flat Plate Collectors for Solar Thermal Scavenging in Low Conductivity Environments

    Directory of Open Access Journals (Sweden)

    Emmanuel Ogbonnaya

    2017-01-01

    Full Text Available There is great opportunity to develop power supplies for autonomous application on the small scale. For example, remote environmental sensors may be powered through the harvesting of ambient thermal energy and heating of a thermoelectric generator. This work investigates a small-scale (centimeters solar thermal collector designed for this application. The absorber is coated with a unique selective coating and then studied in a low pressure environment to increase performance. A numerical model that is used to predict the performance of the collector plate is developed. This is validated based on benchtop testing of a fabricated collector plate in a low-pressure enclosure. Model results indicate that simulated solar input of about 800 W/m2 results in a collector plate temperature of 298 K in ambient conditions and up to 388 K in vacuum. The model also predicts the various losses in W/m2 K from the plate to the surroundings. Plate temperature is validated through the experimental work showing that the model is useful to the future design of these small-scale solar thermal energy collectors.

  3. Local distribution of wall static pressure and heat transfer on a rough flat plate impinged by a slot air jet

    Science.gov (United States)

    Meda, Adimurthy; Katti, Vadiraj V.

    2017-08-01

    The present work experimentally investigates the local distribution of wall static pressure and the heat transfer coefficient on a rough flat plate impinged by a slot air jet. The experimental parameters include, nozzle-to-plate spacing (Z /D h = 0.5-10.0), axial distance from stagnation point ( x/D h ), size of detached rib ( b = 4-12 mm) and Reynolds number ( Re = 2500-20,000). The wall static pressure on the surface is recorded using a Pitot tube and a differential pressure transmitter. Infrared thermal imaging technique is used to capture the temperature distribution on the target surface. It is observed that, the maximum wall static pressure occurs at the stagnation point ( x/D h = 0) for all nozzle-to-plate spacing ( Z/D h ) and rib dimensions studied. Coefficient of wall static pressure ( C p ) decreases monotonically with x/D h . Sub atmospheric pressure is evident in the detached rib configurations for jet to plate spacing up to 6.0 for all ribs studied. Sub atmospheric region is stronger at Z/D h = 0.5 due to the fluid accelerating under the rib. As nozzle to plate spacing ( Z/D h ) increases, the sub-atmospheric region becomes weak and vanishes gradually. Reasonable enhancement in both C p as well as Nu is observed for the detached rib configuration. Enhancement is found to decrease with the increase in the rib width. The results of the study can be used in optimizing the cooling system design.

  4. Laminar-Boundary-Layer Oscillations and Transition on a Flat Plate

    Science.gov (United States)

    1943-04-01

    at a lover 30 viad epeed and at a greater distance froa tbe leading edge of tbe plate ie shown in figure 10. Here tha ampli- fier gala ...dimensional ease; the solutions are therefore the saae. The solutions are applied to the known velo - city profile at the etagnatlon point of a sphere

  5. Numerical investigation of heat transfer enhancement by carbon nano fibers deposited on a flat plate

    NARCIS (Netherlands)

    Pelevic, N.; van der Meer, Theodorus H.

    2013-01-01

    Numerical simulations of flow and heat transfer have been performed for flow over a plate surface covered with carbon nano fibers (CNFs). The CNFs influence on fluid flow and heat transfer has been investigated. Firstly, a stochastic model for CNFs deposition has been explained. Secondly, the

  6. Electromagnetic and Mechanical Characteristics Analysis of a Flat-Type Vertical-Gap Passive Magnetic Levitation Vibration Isolator

    Directory of Open Access Journals (Sweden)

    Baoquan Kou

    2016-01-01

    Full Text Available In this paper, we describe a flat-type vertical-gap passive magnetic levitation vibration isolator (FVPMLVI for active vibration isolation system (AVIS. A dual-stator scheme and a special stator magnet array are adopted in the proposed FVPMLVI, which has the effect of decreasing its natural frequency, and this enhances the vibration isolation capability of the FVPMLVI. The structure, operating principle, analytical model, and electromagnetic and mechanical characteristics of the FVPMLVI are investigated. The relationship between the force characteristics (levitation force, horizontal force, force ripple, and force density and major structural parameters (width and thickness of stator and mover magnets is analyzed by finite element method. The experiment result is in good agreement with the theoretical analysis.

  7. Shed Vortex Structure and Phase-Averaged Velocity Statistics in Symmetric/Asymmetric Turbulent Flat Plate Wakes

    Science.gov (United States)

    Rai, Man Mohan

    2017-01-01

    The near wake of a flat plate is investigated via direct numerical simulations (DNS). Many earlier experimental investigations have used thin plates with sharp trailing edges and turbulent boundary layers to create the wake. This results in large theta divided by D (sub TE) values (theta is the boundary layer momentum thickness towards the end of the plate and D (sub TE) is the trailing edge thickness). In the present study the emphasis is on relatively thick plates with circular trailing edges (CTE) resulting in theta divided by D values less than one (D is the plate thickness and the diameter of the CTE), and vigorous vortex shedding. The Reynolds numbers based on the plate length and D are 1.255 x 10 (sup 6) and 10,000, respectively. Two cases are computed; one with turbulent boundary layers on both the upper and lower surfaces of the plate (statistically the same, symmetric wake, Case TT) and, a second with turbulent and laminar boundary layers on the upper and lower surfaces, respectively (asymmetric case, Case TL). The data and understanding obtained is of considerable engineering interest, particularly in turbomachinery where the pressure side of an airfoil can remain laminar or transitional because of a favorable pressure gradient and the suction side is turbulent. Shed-vortex structure and phase-averaged velocity statistics obtained in the two cases are compared here. The upper negative shed vortices in Case TL (turbulent separating boundary layer) are weaker than the lower positive ones (laminar separating boundary layer) at inception (a factor 1.27 weaker in terms of peak phase-averaged spanwise vorticity at first appearance of a peak). The upper vortices weaken rapidly as they travel downstream. A second feature of interest in Case TL is a considerable increase in the peak phase-averaged, streamwise normal intensity (random component) with increasing streamwise distance (x divided by D) that occurs nears the positive vortex cores. This behavior is

  8. Design of a photovoltaic central power station: flat-plate array

    Energy Technology Data Exchange (ETDEWEB)

    1984-02-01

    A design for a photovoltaic central power station using fixed flat-panel arrays has been developed. The 100 MW plant is assumed to be located adjacent to the Saguaro Power Station of Arizona Public Service. The design assumes high-efficiency photovoltaic modules using dendritic web cells. The modules are arranged in 5 MW subfields, each with its own power conditioning unit. The photovoltaic output is connected to the existing 115 kV utility switchyard. The site specific design allows detailed cost estimates for engineering, site preparation, and installation. Collector and power conditioning costs have been treated parametrically.

  9. A Comparison of the Thermodynamic Efficiency of Vacuum Tube and Flat Plate Solar Collector Systems

    Directory of Open Access Journals (Sweden)

    Juozas Bielskus

    2013-12-01

    Full Text Available The article presents simulation based exergy analysis used for comparing solar thermal systems applied for preparing domestic hot water. The simulation of flat and vacuum tube solar collector systems was performed in TRNSYS simulation environment. A period of one year under Lithuanian climate conditions was chosen. Simulation was performed on 6 min time step resolution by calculating energy and exergy flows and creating balance calculation. Assessment results at system and element levels have been presented as monthly variation in efficiency. The conducted analysis has revealed that the systems designed to cover equal heat energy demand operates in different exergetic efficiencies.Article in Lithuanian

  10. Annual measured and simulated thermal performance analysis of a hybrid solar district heating plant with flat plate collectors and parabolic trough collectors in series

    DEFF Research Database (Denmark)

    Tian, Zhiyong; Perers, Bengt; Furbo, Simon

    2017-01-01

    the district heating network to about 70 °C and then the parabolic trough collectors would heat the preheated water to the required supply temperature of the district heating network. Annual measured and simulated thermal performances of both the parabolic trough collector field and the flat plate collector...... in large solar heating plants for a district heating network, a hybrid solar collector field with 5960 m2 flat plate collectors and 4039 m2 parabolic trough collectors in series was constructed in Taars, Denmark. The design principle is that the flat plate collectors preheat the return water from...... field are presented in this paper. The thermal performance of both collector fields with weather data of a Design Reference Year was simulated to have a whole understanding of the application of both collectors under Danish climate conditions as well. These results not only can provide a design basis...

  11. Critical heat flux on a flat plate heater located at the middle of a duct in forced flow of pressurized He II

    Science.gov (United States)

    Okamura, T.; Saeki, M.; Hata, K.; Hama, K.; Shirai, Y.; Shiotsu, M.

    2004-09-01

    Critical heat fluxes (CHFs) were measured for two types of rectangular ducts containing horizontal flat plate heaters. One has the flat plate heater of 6 mm wide and 20 mm long located on the inner lower wall at 50 mm from the inlet. The other duct has two horizontal flat plates of 6 mm wide and 20 mm long on inner upper and lower walls at 50 mm from the inlet. The equation of CHF for the forced convection containing a new nondimensional-parameter m introduced in order to calculate cross-sectionally averaged liquid temperature at the center of the duct was derived based on two fluid model, ordinary convection theorem and experimental results. It was confirmed that this correlation can describe not only the author's data on the duct but also other worker's data for channels with different shapes and sizes.

  12. A Method for Calculating the Induced Pressure Distribution Associated with a Jet in a Crossflow. M.S. Thesis; [for a flat plate

    Science.gov (United States)

    Dietz, W. E., Jr.

    1975-01-01

    A model is presented which can be used to study the loss of lift during hovering and horizontal flight of the VTOL aircraft. The model numerically predicts the pressure distribution induced by a round, turbulent, unheated, subsonic jet exhausting normally through a flat plate into a subsonic crossflow. The complete model assumes that the predominant features of the flow are jet entrainment and a pair of contrarotating vortices which form downstream of the jet. Experimentally determined vortex properties and a reasonable assumption concerning jet entrainment were used. Potential flow considerations were used except in the wake region, where a simple method for approximating the pressure distribution was suggested. The calculated pressure distribution, lift, and pitching moments on the flat plate are presented for a jet to crossflow velocity ratio of 8 and were compared with experimental results. A computer program is given which was used to calculate the pressure distribution across the flat plate.

  13. Tests and Evaluation of Upgraded Flat-Plate and Waffle-Slab Floor Systems

    Science.gov (United States)

    1983-12-01

    plate test specimen was constructed to include the positive moment area from a 22-ft-square slab designed according to the Third Edition of the CRSI ... CRSI Handbook. The waffle-slab specimens were constructed to include positive mo- ment areas from 24-foot-square slabs. An 8-inch-thick wall, 8 feet...portions were designed in accordance with the design of a waffle-slab floor given in the Concrete Reinforcing Steel Institute ( CRSI ) Handbook (Ref

  14. Effects of the foil flatness on the stress-strain characteristics of U10Mo alloy based monolithic mini-plates

    Energy Technology Data Exchange (ETDEWEB)

    Hakan Ozaltun; Pavel Medvedev

    2014-11-01

    The effects of the foil flatness on stress-strain behavior of monolithic fuel mini-plates during fabrication and irradiation were studied. Monolithic plate-type fuels are a new fuel form being developed for research and test reactors to achieve higher uranium densities. This concept facilitates the use of low-enriched uranium fuel in the reactor. These fuel elements are comprised of a high density, low enrichment, U–Mo alloy based fuel foil encapsulated in a cladding material made of Aluminum. To evaluate the effects of the foil flatness on the stress-strain behavior of the plates during fabrication, irradiation and shutdown stages, a representative plate from RERTR-12 experiments (Plate L1P756) was considered. Both fabrication and irradiation processes of the plate were simulated by using actual irradiation parameters. The simulations were repeated for various foil curvatures to observe the effects of the foil flatness on the peak stress and strain magnitudes of the fuel elements. Results of fabrication simulations revealed that the flatness of the foil does not have a considerable impact on the post fabrication stress-strain fields. Furthermore, the irradiation simulations indicated that any post-fabrication stresses in the foil would be relieved relatively fast in the reactor. While, the perfectly flat foil provided the slightly better mechanical performance, overall difference between the flat-foil case and curved-foil case was not significant. Even though the peak stresses are less affected, the foil curvature has several implications on the strain magnitudes in the cladding. It was observed that with an increasing foil curvature, there is a slight increase in the cladding strains.

  15. Experimental study of the lift and drag characteristics of a cascade of flat plates in a configuration of interest for tidal energy converters

    Science.gov (United States)

    Fedoul, Faical; Parras, Luis; Del Pino, Carlos; Fernandez-Feria, Ramon

    2012-11-01

    Wind tunnel experiments are conducted for the flow around both a single flat plate and a cascade of three parallel flat plates at different angles of incidence to compare their lift and drag coefficients in a range of Reynolds number about 105, and for two values of the aspect ratio of the flat plates. The selected cascade configuration is of interest for a particular type of tidal energy converter. The lift and drag characteristics of the central plate in the cascade are compared to those of the isolated plate, finding that there exist an angle of incidence, which depends on the Reynolds number and the aspect ratio, above which the effective lift of the plate in the cascade becomes larger than that of an isolated plate. These experimental results, which are also analyzed in the light of theoretical predictions, are used as a guide for the design of the optimum configuration of the cascade which extracts the maximum power from a tidal current for a given value of the Reynolds number. Supported by the Ministerio de Ciencia e Innovacion (Spain) Grant no. ENE2010-16851.

  16. On a model of oscillations of a thin flat plate with a variety of mounts on opposite sides

    Science.gov (United States)

    Kal'menov, Tynysbek; Iskakova, Ulzada

    2016-12-01

    In this paper we consider a model case of stationary vibrations of a thin flat plate, one side of which is embedded, the opposite side is free, and the sides are freely leaned. In mathematical modeling there is a local boundary value problem for the biharmonic equation in a rectangular domain. Boundary conditions are given on all boundary of the domain. We show that the considered problem is self-adjoint. Herewith the problem is ill-posed. We show that the stability of solution to the problem is disturbed. Necessary and sufficient conditions of existence of the problem solution are found. Spaces of the ill-posedness of the considered problem are constructed.

  17. CHF for Downward-facing Flat Plates considering Pressure up to 2 bar condition, Width and Material Effects

    Energy Technology Data Exchange (ETDEWEB)

    Kam, Dong Hoon; Choi, Young Jae; Jeong, Yong Hoon [KAIST, Daejeon (Korea, Republic of)

    2016-05-15

    Combined effects should be assessed to fully cover the effects of main parameters on the downward-facing flat plates. Based on the preceding results considering width and material effects under atmospheric condition, pressure effect was added in this study. Width effect has been assessed for stainless steel under pressurized conditions. Width effect decreased as pressure increased for wide test sections. When considering material effect, some different trend was noticed depending on the width sizes. For the 40 mm width case, enhancement decreased somehow as pressure increased up to 2 bar condition, and for the 50 mm-width case, carbon steel sometimes showed lower value compared with the reference material under 2 bar condition.

  18. Investigation of thermal behaviour, pressure drop, and pumping power in a Cu nanofluid-filled solar flat-plate collector

    Directory of Open Access Journals (Sweden)

    Shamshirgaran S. Reza

    2017-01-01

    Full Text Available The evaluations of the performance of solar flat-plate collectors are reported in the literature. A computer program developed by MATLAB has been applied for modelling the performance of a solar collector under steady state laminar conditions. Results demonstrate that Cu-water nanofluid would be capable of boosting the thermal efficiency of the collector by 2.4% at 4% volume concentration in the case of using Cunanofluid instead of just water as the working fluid. It is noteworthy that, dispersing the nanoparticles into the water results in a higher pressure drop and, therefore, a higher power consumption for pumping the nanofluid within the collector. It has been estimated for the collector understudy, that the increase in the pressure drop and pumping power to be around 30%.

  19. Investigation of Thermal Performance of Flat Plate and Evacuated Tubular Solar Collectors According to a New Dynamic Test Method

    DEFF Research Database (Denmark)

    Kong, Weiqiang; Wang, Zhifeng; Fan, Jianhua

    2012-01-01

    A new dynamic test method is introduced. This so called improved transfer function method features on two new collector parameters. One is time term which can indicate solar collector's inner heat transfer ability and the other is a second order term of collector mean fluid temperature which can...... obtain fluid thermal capacitance in data processing. Then theoretical analysis and experimental verification are carried out to investigate influencing factors of obtaining accurate and stable second order term. A flat plate and ETC solar collector are compared using both the new dynamic method...... and a standard method. The results show that the improved function method can accurately and robustly estimate these two kinds of solar collectors....

  20. Tårs 10000 m2 CSP + Flat Plate Solar Collector Plant - Cost-Performance Optimization of the Design

    DEFF Research Database (Denmark)

    Perers, Bengt; Furbo, Simon; Tian, Zhiyong

    2016-01-01

    A novel solar heating plant with Concentrating Solar Power (CSP) collectors and Flat Plate (FP) collectors has been put into operation in Tårs since July 2015. To investigate economic performance of the plant, a TRNSYS-Genopt model, including a solar collector field and thermal storage tank......, was established. The optimization showed that there was a synergy in combining CSP and FP collectors. Even though the present cost per m² of the CSP collectors is high, the total energy cost is minimized by installing a combination of collectors in such solar heating plant. It was also found that the CSP...... collectors could raise flexibility in the control strategy of the plant. The TRNSYS-Genopt model is based on individually validated component models and collector parameters from experiments. Optimization of the cost performance of the plant has been conducted in this paper. The simulation model remains...

  1. Fluctuating pressures measured beneath a high-temperature, turbulent boundary layer on a flat plate at Mach number of 5

    Science.gov (United States)

    Parrott, Tony L.; Jones, Michael G.; Albertson, Cindy W.

    1989-01-01

    Fluctuating pressures were measured beneath a Mach 5, turbulent boundary layer on a flat plate with an array of piezoresistive sensors. The data were obtained with a digital signal acquisition system during a test run of 4 seconds. Data sampling rate was such that frequency analysis up to 62.5 kHz could be performed. To assess in situ frequency response of the sensors, a specially designed waveguide calibration system was employed to measure transfer functions of all sensors and related instrumentation. Pressure time histories were approximated well by a Gaussian prohibiting distribution. Pressure spectra were very repeatable over the array span of 76 mm. Total rms pressures ranged from 0.0017 to 0.0046 of the freestream dynamic pressure. Streamwise, space-time correlations exhibited expected decaying behavior of a turbulence generated pressure field. Average convection speed was 0.87 of freestream velocity. The trendless behavior with sensor separation indicated possible systematic errors.

  2. Stand-alone flat-plate photovoltaic power systems: System sizing and life-cycle costing methodology for Federal agencies

    Science.gov (United States)

    Borden, C. S.; Volkmer, K.; Cochrane, E. H.; Lawson, A. C.

    1984-01-01

    A simple methodology to estimate photovoltaic system size and life-cycle costs in stand-alone applications is presented. It is designed to assist engineers at Government agencies in determining the feasibility of using small stand-alone photovoltaic systems to supply ac or dc power to the load. Photovoltaic system design considerations are presented as well as the equations for sizing the flat-plate array and the battery storage to meet the required load. Cost effectiveness of a candidate photovoltaic system is based on comparison with the life-cycle cost of alternative systems. Examples of alternative systems addressed are batteries, diesel generators, the utility grid, and other renewable energy systems.

  3. Development of Streamwise Counter-Rotating Vortices in Flat Plate Boundary Layer Pre-set by Leading Edge Patterns

    KAUST Repository

    Hasheminejad, S.M.

    2017-04-03

    Development of streamwise counter-rotating vortices induced by leading edge patterns with different pattern shape is investigated using hot-wire anemometry in the boundary layer of a flat plate. A triangular, sinusoidal and notched patterns with the same pattern wavelength λ of 15mm and the same pattern amplitude A of 7.5mm were examined for free-stream velocity of 3m/s. The results show a good agreement with earlier studies. The inflection point on the velocity profile downstream of the trough of the patterns at the beginning of the vortex formation indicates that the vortices non-linearly propagate downstream. An additional vortex structure was also observed between the troughs of the notched pattern.

  4. Large-eddy simulation of separation and reattachment of a flat plate turbulent boundary layer

    KAUST Repository

    Cheng, W.

    2015-11-11

    © 2015 Cambridge University Press. We present large-eddy simulations (LES) of separation and reattachment of a flat-plate turbulent boundary-layer flow. Instead of resolving the near wall region, we develop a two-dimensional virtual wall model which can calculate the time- and space-dependent skin-friction vector field at the wall, at the resolved scale. By combining the virtual-wall model with the stretched-vortex subgrid-scale (SGS) model, we construct a self-consistent framework for the LES of separating and reattaching turbulent wall-bounded flows at large Reynolds numbers. The present LES methodology is applied to two different experimental flows designed to produce separation/reattachment of a flat-plate turbulent boundary layer at medium Reynolds number Reθ based on the momentum boundary-layer thickness θ. Comparison with data from the first case at demonstrates the present capability for accurate calculation of the variation, with the streamwise co-ordinate up to separation, of the skin friction coefficient, Reθ, the boundary-layer shape factor and a non-dimensional pressure-gradient parameter. Additionally the main large-scale features of the separation bubble, including the mean streamwise velocity profiles, show good agreement with experiment. At the larger Reθ = 11000 of the second case, the LES provides good postdiction of the measured skin-friction variation along the whole streamwise extent of the experiment, consisting of a very strong adverse pressure gradient leading to separation within the separation bubble itself, and in the recovering or reattachment region of strongly-favourable pressure gradient. Overall, the present two-dimensional wall model used in LES appears to be capable of capturing the quantitative features of a separation-reattachment turbulent boundary-layer flow at low to moderately large Reynolds numbers.

  5. A Flat Solar Collector Built from Galvanized Steel Plate, Working by Thermosyphonic Flow, Optimized for Mexican Conditions

    Directory of Open Access Journals (Sweden)

    Á. Marroquín de Jesús

    2009-07-01

    Full Text Available Design, construction, and testing of the thermal performance of a flat solar collector for domestic water heating are described. The absorbing plate is built from readily available materials: two sheets of galvanized steel, one of the channelled type, the other one flat, which are joined by electric welding. The absorber is connected to a 198–L thermotank, insulated with polyurethane foam. In terms of receiving surface, the prototype tested here has an area of 1.35 m2, about 20% smaller than comparable copper–tube–based collectors offered in the market. Temperature measurements conducted over a 30–day period gave values which were a few degrees lower than the theoretically calculated water temperatures. Momentary thermal efficiency values between 35% and 77% were observed. The water temperature achieved in the tank at the end of the day aver ages 65°C in winter weather conditions in the central Mexican highland. This design of solar water heater is well suited to Mexican conditions, as it makes use of the high local intensity of the solar radiation, and as the channel shape of the ducts minimizes bursting during the rare occurrences of freezing temperatures in the region; it also has the advantage of being manufacturable at low cost from simple materials.

  6. Development of flow and heat transfer in the vicinity of a vertical plate embedded in a porous medium with viscous dissipation effects

    KAUST Repository

    El-Amin, Mohamed

    2012-01-01

    In this paper, the effects of viscous dissipation on unsteady free convection from an isothermal vertical flat plate in a fluidsaturated porous medium are investigated. The Darcy-Brinkman model is employed to describe the flow field. A new model of viscous dissipation is used for the Darcy-Brinkman model of porous media. The simultaneous development of the momentum and thermal boundary layers is obtained by using a finite-difference method. Boundary layer and Boussinesq approximation have been incorporated. Numerical calculations are carried out for various parameters entering into the problem. Velocity and temperature profiles as well as the local friction factor and local Nusselt number are displayed graphically. It is found that as time approaches infinity, the values of the friction factor and heat transfer coefficient approach steady state. © 2012 by Begell House, Inc.

  7. Unsteady natural convection flow of nanofluids past a semi-infinite isothermal vertical plate

    Science.gov (United States)

    Tippa, Sowmya; Narahari, Marneni; Pendyala, Rajashekhar

    2016-11-01

    Numerical analysis is performed to investigate the unsteady natural convection flow of a nanofluid past a semi-infinite isothermal vertical plate. Five different types of water based nanofluids are considered in this investigation where Silver (Ag), Copper (Cu), Copper Oxide (CuO), Alumina (Al2O3) and Titanium Oxide (TiO2) are the nanoparticles. The governing non-dimensional partial differential equations are solved by employing an implicit finite-difference method of Crank-Nicolson type. Numerical results are computed for different values of pertinent parameters. The results for nanofluid temperature, velocity, local Skin friction and Nusselt number, average Skin friction and Nusselt number are discussed through graphs. The present numerical results for local Nusselt number have been compared with the well-established pure fluid correlation results for the limiting case and the comparison shows that the results are in excellent agreement.

  8. Dufour and Soret Effects on Melting from a Vertical Plate Embedded in Saturated Porous Media

    Directory of Open Access Journals (Sweden)

    Basant K. Jha

    2013-01-01

    Full Text Available Thermal-diffusion and diffusion-thermo effects on combined heat and mass transfer in mixed convection boundary layer flow with aiding and opposing external flows from a vertical plate embedded in a liquid saturated porous medium with melting are investigated. The resulting system of nonlinear ordinary differential equations is solved numerically using Runge Kutta-Fehlberg with shooting techniques. Numerical results are obtained for the velocity, temperature, and concentration distributions, as well as the Nusselt number and Sherwood number for several values of the parameters, namely, the buoyancy parameter, melting parameter, Dufour effect, Soret effect, and Lewis number. The obtained results are presented graphically and in tabular form and the physical aspects of the problem are discussed.

  9. Chemical reaction effect on MHD free convective surface over a moving vertical plate through porous medium

    Directory of Open Access Journals (Sweden)

    R.S. Tripathy

    2015-09-01

    Full Text Available An attempt has been made to study the heat and mass transfer effect in a boundary layer flow of an electrically conducting viscous fluid subject to transverse magnetic field past over a moving vertical plate through porous medium in the presence of heat source and chemical reaction. The governing non-linear partial differential equations have been transformed into a two-point boundary value problem using similarity variables and then solved numerically by fourth order Runge–Kutta fourth order method with shooting technique. Graphical results are discussed for non-dimensional velocity, temperature and concentration profiles while numerical values of the skin friction, Nusselt number and Sherwood number are presented in tabular form for various values of parameters controlling the flow system.

  10. Flow reversal of laminar mixed convection in the entry region of symmetrically heated, vertical plate channels

    Energy Technology Data Exchange (ETDEWEB)

    Desrayaud, G. [Universite de Picardie Jules Verne, INSSET, Lab. Modelisation et Simulation Multi Echelle, MSME FRE 3160 CNRS, 02 - Saint-Quentin (France); Lauriat, G. [Universite Paris-Est, Lab. Modelisation et Simulation Multi Echelle, MSME FRE 3160 CNRS, 77 - Marne-la-Vallee (France)

    2009-11-15

    The present numerical investigation is concerned with flow reversal phenomena for laminar, mixed convection of air in a vertical parallel-plate channel of finite length. Results are obtained for buoyancy-assisted flow in a symmetrically heated channel with uniform wall temperatures for various Grashof numbers and Reynolds numbers in the range 300 {<=} Re {<=} 1300. The effects of buoyancy forces on the flow pattern are investigated and the shapes of velocity and temperature profiles are discussed in detail. Flow reversals centred in the entrance of the channel are predicted. The strength of the cells decreases as the Reynolds number is increased, until they disappear. The regime of reversed flow is identified for high values of the Peclet number in a Pe-Gr/Re map. It is also shown that the channel length has no influence on the occurrence of the reversal flow provided that H/D {>=} 10. (authors)

  11. Effects of parabolic motion on an isothermal vertical plate with constant mass flux

    Directory of Open Access Journals (Sweden)

    R. Muthucumaraswamy

    2014-12-01

    Full Text Available An analytical study of free convection flow near a parabolic started infinite vertical plate with isothermal in the presence of uniform mass flux was considered. The mathematical model is reduced to a system of linear partial differential equations for the velocity, the concentration and the temperature; the closed form exact solutions were obtained by the Laplace transform technique. The velocity, temperature and concentration profiles for the different parameters as thermal Grashof number Gr, mass Grashof number Gc, Prandtl number Pr, Schmidt number Sc and time t were graphed and the numerical values for the skin friction were as tabulated. It is observed that the velocity is enhanced as the time increased and the velocity is decreased as the Prandtl number increased.

  12. Effects of flanges on pressure distribution on a flat plate and on a corrugated surface at Mach numbers from 0.60 to 1.97

    Science.gov (United States)

    Johns, A. L.; Jones, M. L.

    1974-01-01

    An 8 by 6 foot supersonic wind tunnel was used to obtain the static pressure distribution on a plate in the region of a flange placed normal to the airstream. Tests were conducted on both a flat plate surface and a corrugated surface using flange heights ranging from 10 to 125 percent of the boundary layer height. Data were obtained at a zero degree angle-of-attack and at Mach numbers from 0.60 to 1.97.

  13. Catalyzed combustion in a flat plate boundary layer. II. Numerical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Schefer, R.; Robben, F.

    1977-09-01

    A computer program has been developed to solve the boundary layer equations for laminar flow over a heated plate with H/sub 2//air combustion. The objectives are to investigate the importance of homogeneous as opposed to catalytic surface reactions during the combustion process, and to determine the roles of heat and mass transfer and their effect on combustion. Results are presented for combustion of H/sub 2//air at an equivalence ratio of 0.1 for flow over a noncatalytic plate at a surface temperature of 1100/sup 0/K. A detailed mechanism involving 8 chemical species and 13 reactions has been used to describe the kinetics. The reactions leading to the initiation of combustion and the effect of the large diffusivity of hydrogen are discussed. The boundary conditions for catalytic surface and a simplified model to account for catalytic wall reaction are formulated. Results are presented for combustion over a catalytic surface and compared with the non-catalytic case.

  14. Effects of velocity profile and inclination on dual-jet-induced pressures on a flat plate in a crosswind

    Science.gov (United States)

    Jakubowski, A. L.; Schetz, J. A.; Moore, C. L.; Joag, R.

    1985-01-01

    An experimental study was conducted to determine surface pressure distributions on a flat plate with dual subsonic, circular jets exhausting from the surface into a crossflow. The jets were arranged in both side-by-side and tandem configurations and were injected at 90 deg and 60 deg angles to the plate, with jet-to-crossflow velocity ratio of 2.2 and 4. The major objective of the study was to determine the effect of a nonuniform (vs uniform) jet velocity profile, simulating the exhaust of a turbo-fan engine. Nonuniform jets with a high-velocity outer annulus and a low-velocity core induced stronger negative pressure fields than uniform jets with the same mass flow rate. However, nondimensional lift losses (lift loss/jet thrust lift) due to such nonuniform jets were lower than lift losses due to uniform jets. Changing the injection angle from 90 deg to 60 deg resulted in moderate (for tandem jets) to significant (for side-by-side jets) increases in the induced negative pressures, even though the surface area influenced by the jets tended to reduce as the angle decreased. Jets arranged in the side-by-side configuration led to significant jet-induced lift losses exceeding, in some cases, lift losses reported for single jets.

  15. A study on the effect of flat plate friction resistance on speed performance prediction of full scale

    Directory of Open Access Journals (Sweden)

    Dong-Woo Park

    2015-01-01

    Full Text Available Flat plate friction lines have been used in the process to estimate speed performance of full-scale ships in model tests. The results of the previous studies showed considerable differences in determining form factors depending on changes in plate friction lines and Reynolds numbers. These differences had a great influence on estimation of speed performance of full-scale ships. This study was conducted in two parts. In the first part, the scale effect of the form factor depending on change in the Reynolds number was studied based on CFD, in connection with three kinds of friction resistance curves: the ITTC-1957, the curve proposed by Grigson (1993; 1996, and the curve developed by Katsui et al. (2005. In the second part, change in the form factor by three kinds of friction resistance curves was investtigated based on model tests, and then the brake power and the revolution that were finally determined by expansion processes of full-scale ships. When three kinds of friction resistance curves were applied to each kind of ships, these were investigated: differences between resistance and self-propulsion components induced in the expansion processes of full-scale ships, correlation of effects between these components, and tendency of each kind of ships. Finally, what friction resistance curve was well consistent with results of test operation was examined per each kind of ships.

  16. MHD Heat and Mass Transfer of Chemical Reaction Fluid Flow over a Moving Vertical Plate in Presence of Heat Source with Convective Surface Boundary Condition

    Directory of Open Access Journals (Sweden)

    B. R. Rout

    2013-01-01

    Full Text Available This paper aims to investigate the influence of chemical reaction and the combined effects of internal heat generation and a convective boundary condition on the laminar boundary layer MHD heat and mass transfer flow over a moving vertical flat plate. The lower surface of the plate is in contact with a hot fluid while the stream of cold fluid flows over the upper surface with heat source and chemical reaction. The basic equations governing the flow, heat transfer, and concentration are reduced to a set of ordinary differential equations by using appropriate transformation for variables and solved numerically by Runge-Kutta fourth-order integration scheme in association with shooting method. The effects of physical parameters on the velocity, temperature, and concentration profiles are illustrated graphically. A table recording the values of skin friction, heat transfer, and mass transfer at the plate is also presented. The discussion focuses on the physical interpretation of the results as well as their comparison with previous studies which shows good agreement as a special case of the problem.

  17. A development of the method of the control signal formation for the hot plate mill automation systems to improve the flatness of the finish plate

    Directory of Open Access Journals (Sweden)

    Voronin Stanislav S.

    2016-01-01

    Full Text Available This article describes how to control of the hot plate mill automation system to improve the quality metrics if the final strip. Based on the data of the modern hot rolling mills the classification of the cage equipment was designed. Depending on the degree of influence on the magnitude of reduction, the equipment was divided into categories. The functioning of every system including the main and the vertical cages was described. The conditions of electrical and hydraulic mechanisms was marked. The developed algorithm allows to improve defects based on the finite number of the thickness measurements given by special non-contact sensors. The example of regulators signals calculating was shown. The result of the algorithm operating was illustrated.

  18. Inspection of welded zone and flat plate using flexible ECA probe

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Jun; Lee, Kyu Sung; Shin, Chung Ho; Lee, Kyoung Jun; Jang, Yoon Young [ANSCO Inc., Daejeon (Korea, Republic of)

    2016-08-15

    This paper aims to compare the ability to detect notch defects existing in the plate and welded area using a flexible ECA (eddy current array) probe with OmniScan MX and MS-5800E. The characteristics of signals with various frequencies and lift-offs were also compared. As a result, when signals of frequencies 500, 1000, and 1500 kHz were used, the amplitude of the signal increased, as the depth of the notch increased, but reduced linearly in accordance with the lift-off variation. In addition, the detection sensitivity of the weld defect was found to be closely related to the contact surface of the probe and specimen. In this paper, it was demonstrated that the detection sensitivity was excellent when the contact surface of the probe and the specimen was sufficient, but it was poor when the contact surface was insufficient.

  19. Development and life cycle analysis of double slope active solar still with flat plate collector

    Directory of Open Access Journals (Sweden)

    A.K. Sethi

    2014-02-01

    Full Text Available Potable water is an essential ingredient of socio-economic development and economic growth. Often water sources are brackish (i.e. contain dissolved salts and/or contain harmful bacteria and therefore cannot be used for drinking. In addition, there are many coastal locations where seawater is abundant but potable water is not available. This study is focused on a development of solar still with flat plat collector for water desalination considered for small scale applications at remote locations where only saline water is available. In this paper the cost of distilled water per kg has been calculated by using the concept of life cycle cost analysis. The pay back periods for different conditions of the distribution of distilled water, namely at the cost it is produced and at the selling price on market rate have been evaluated. The cost of water per kg is minimum Rs. 0.59, when the interest rate and the lifetime of solar still are taken as 4% and 50 years respectively. The lowest payback time 1.23 years is obtained when the selling price of water Rs. 10 per kg.

  20. Buoyancy effects on thermal behavior of a flat-plate solar collector

    DEFF Research Database (Denmark)

    Fan, Jianhua; Furbo, Simon

    2008-01-01

    Theoretical and experimental investigations of the flow and temperature distribution in a 12.53 m(2) solar collector panel with an absorber consisting of two vertical manifolds interconnected by 16 parallel horizontal fins have been carried out. The investigations are focused on overheating...... and the influence of the buoyancy effects are considered in the investigations. Further experimental investigations of the solar collector panel are carried out. The flow distribution through the absorber is evaluated by means of temperature measurements on the back of the absorber tubes. The measured temperatures....... The CFD calculations elucidate the flow and temperature distribution in the collector panels of different designs. Based on the investigations, recommendations are given in order to avoid overheating or boiling problems in the solar collector panel....

  1. High-Reynolds-number flat-plate turbulent boundary layer measurements

    Science.gov (United States)

    Winkel, Eric S.; Cutbirth, James M.; Perlin, Marc; Ceccio, Steven L.; Dowling, David R.

    2006-11-01

    A set of experiments was conducted in the U.S. Navy's Large Cavitation Channel (LCC) into the characteristics of a liquid turbulent boundary layer at nearly zero-pressure-gradient. The hydraulically smooth, k^+ centered in the LCC test section. Data was gathered at flow speeds up to 20 m/s to achieve downstream-distance-based Reynolds numbers up to 220 million. Static pressure, skin-friction, and laser-Doppler velocimetry (LDV) measurements are presented. Static pressure measurements along the plate surface show a mild favorable pressure gradient, less than 2.5% flow acceleration over the model. Skin-friction was measured at six stream-wise positions with 15-cm-diameter, flush-mounted drag-balances. Flow profiles of the mean and second-order turbulence statistics of stream-wise and wall-normal velocity components were measured using two-component LDV. When normalized with the measured skin-friction, mean velocity profiles agree with the accepted law-of-the-wall constants and the total near-wall shear stress approaches unity.

  2. Computational Fluid Dynamics Uncertainty Analysis Applied to Heat Transfer over a Flat Plate

    Science.gov (United States)

    Groves, Curtis Edward; Ilie, Marcel; Schallhorn, Paul A.

    2013-01-01

    There have been few discussions on using Computational Fluid Dynamics (CFD) without experimental validation. Pairing experimental data, uncertainty analysis, and analytical predictions provides a comprehensive approach to verification and is the current state of the art. With pressed budgets, collecting experimental data is rare or non-existent. This paper investigates and proposes a method to perform CFD uncertainty analysis only from computational data. The method uses current CFD uncertainty techniques coupled with the Student-T distribution to predict the heat transfer coefficient over a at plate. The inputs to the CFD model are varied from a specified tolerance or bias error and the difference in the results are used to estimate the uncertainty. The variation in each input is ranked from least to greatest to determine the order of importance. The results are compared to heat transfer correlations and conclusions drawn about the feasibility of using CFD without experimental data. The results provide a tactic to analytically estimate the uncertainty in a CFD model when experimental data is unavailable

  3. Engineering applications and analysis of vibratory motion fourth order fluid film over the time dependent heated flat plate

    Science.gov (United States)

    Mohmand, Muhammad Ismail; Mamat, Mustafa Bin; Shah, Qayyum

    2017-07-01

    This article deals with the time dependent analysis of thermally conducting and Magneto-hydrodynamic (MHD) liquid film flow of a fourth order fluid past a vertical and vibratory plate. In this article have been developed for higher order complex nature fluids. The governing-equations have been modeled in the terms of nonlinear partial differential equations with the help of physical boundary circumstances. Two different analytical approaches i.e. Adomian decomposition method (ADM) and the optimal homotopy asymptotic method (OHAM), have been used for discoveryof the series clarification of the problems. Solutions obtained via two diversemethods have been compared using the graphs, tables and found an excellent contract. Variants of the embedded flow parameters in the solution have been analysed through the graphical diagrams.

  4. An Experimental and Numerical Study of Diesel Spray Impingement on a Flat Plate

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Le; Torelli, Roberto; Zhu, Xiucheng; Scarcelli, Riccardo; Som, Sibendu; Schmidt, Henry; Naber, Jeffrey; Lee, Seong-Young

    2017-03-14

    Combustion systems with advanced injection strategies have been extensively studied, but there still exists a significant fundamental knowledge gap on fuel spray interactions with the piston surface and chamber walls. This paper is meant to provide detailed data on spray-wall impingement physics and support the spray-wall model development. The experimental work of spray-wall impingement with non-vaporizing spray characterization, was carried out in a high pressure-temperature constant-volume combustion vessel. The simultaneous Mie scattering of liquid spray and schlieren of liquid and vapor spray were carried out. Diesel fuel was injected at a pressure of 1500 bar into ambient gas at a density of 22.8 kg/m3 with isothermal conditions (fuel, ambient, and plate temperatures of 423 K). A Lagrangian-Eulerian modeling approach was employed to characterize the spray-gas and spray-wall interactions in the CONVERGE framework by means of a Reynolds-Averaged Navier-Stokes (RANS) formulation. A set of turbulence and spray break-up model constants was identified to properly match the aforementioned measurements of liquid penetration within their experimental confidence intervals. An accuracy study on varying the minimum mesh size was also performed to ensure the grid convergence of the numerical results. Experimentally validated computational fluid dynamics (CFD) simulations were then used to investigate the local spray characteristics in the vicinity of the wall with a particular focus on Sauter Mean Diameter (SMD) and Reynolds and Weber numbers. The analysis was performed by considering before- and after-impingement conditions in order to take in account the influence of the impinged wall on the spray morphology.

  5. Newtonian heating effect on unsteady hydromagnetic Casson fluid flow past a flat plate with heat and mass transfer

    Directory of Open Access Journals (Sweden)

    M. Das

    2015-12-01

    Full Text Available The influence of Newtonian heating on heat and mass transfer in unsteady hydromagnetic flow of a Casson fluid past a vertical plate in the presence of thermal radiation and chemical reaction is studied. The Casson fluid model is used to distinguish the non-Newtonian fluid behavior. The fluid flow is induced due to periodic oscillations of the plate along its length and a uniform transverse magnetic field is applied in a direction which is normal to the direction of fluid flow. The partial differential equations governing the flow, heat, and mass transfer are transformed to non-dimensional form using suitable non-dimensional variables which are then solved analytically by using Laplace transform technique. The numerical values of the fluid velocity, fluid temperature, and species concentration are depicted graphically whereas the values of skin-friction, Nusselt number, and Sherwood number are presented in tabular form. It is noticed that the fluid velocity and temperature decrease with increasing values of Casson parameter while concentration decreases with increasing values of chemical reaction parameter and Schmidt number. Such a fluid flow model has several industrial and medical applications such as in glass manufacturing, paper production, purification of crude oil and study of blood flow in the cardiovascular system.

  6. The turbulence structure of the wake of a thin flat plate at post-stall angles of attack

    Science.gov (United States)

    Mohebi, Meraj; Wood, David H.; Martinuzzi, Robert J.

    2017-06-01

    The influence of post-stall angles of attack, α, on the turbulent flow characteristics behind a thin high aspect ratio flat plate was investigated experimentally. Time-resolved stereo particle image velocimetry was used in an open-section wind tunnel at a Reynolds number of 6600. The mean field was determined along with the wake topology, force coefficients, vortex shedding frequency, and the terms in the transport equation for the turbulent kinetic energy k. Coherent and incoherent contributions to the Reynolds stress and k-transport terms were estimated. Over the measured range of 20° ≤ α ≤ 90°, quasi-periodic vortex shedding is observed and it is shown that most of the fluctuation energy contribution in the wake arises from coherent fluctuations associated with vortex shedding. As the angle of attack is reduced from 90°, the length of the recirculation region and the drag decrease, while the shedding frequency increases monotonically. In contrast, mean lift and k are maximized at α ≈ 40°, suggesting a relationship between the bound vortex circulation and the levels of k. Structural differences in the mean strain field, wake topology, relative contributions to the k-production terms, and significant differences in the incoherent field suggest changes in the wake dynamics for α > 40° and 20° ≤ α ≤ 40°. For α > 40°, coherent contributions to the fluctuation field result in a large region close to the plate exhibiting small levels of negative mean production and generally low levels of advection, despite very high levels of production just downstream of the recirculation region.

  7. Analysis of Heat Transfer and Pressure Drop for a Gas Flowing Through a set of Multiple Parallel Flat Plates at High Temperatures

    Science.gov (United States)

    Einstein, Thomas H.

    1961-01-01

    Equations were derived representing heat transfer and pressure drop for a gas flowing in the passages of a heater composed of a series of parallel flat plates. The plates generated heat which was transferred to the flowing gas by convection. The relatively high temperature level of this system necessitated the consideration of heat transfer between the plates by radiation. The equations were solved on an IBM 704 computer, and results were obtained for hydrogen as the working fluid for a series of cases with a gas inlet temperature of 200 R, an exit temperature of 5000 0 R, and exit Mach numbers ranging from 0.2 to O.8. The length of the heater composed of the plates ranged from 2 to 4 feet, and the spacing between the plates was varied from 0.003 to 0.01 foot. Most of the results were for a five- plate heater, but results are also given for nine plates to show the effect of increasing the number of plates. The heat generation was assumed to be identical for each plate but was varied along the length of the plates. The axial variation of power used to obtain the results presented is the so-called "2/3-cosine variation." The boundaries surrounding the set of plates, and parallel to it, were assumed adiabatic, so that all the power generated in the plates went into heating the gas. The results are presented in plots of maximum plate and maximum adiabatic wall temperatures as functions of parameters proportional to f(L/D), for the case of both laminar and turbulent flow. Here f is the Fanning friction factor and (L/D) is the length to equivalent diameter ratio of the passages in the heater. The pressure drop through the heater is presented as a function of these same parameters, the exit Mach number, and the pressure at the exit of the heater.

  8. Numerical investigation for heat transfer enhancement using nanofluids over ribbed confined one-end closed flat-plate

    Directory of Open Access Journals (Sweden)

    Mohamed M. Hassan

    2017-09-01

    Full Text Available Impinging jet is one of various methods of cooling with the ability to achieve high heat transfer rates and improve average surface’s Nusselt number. This method has vast industrial applications including integrated use in solar collectors, gas turbine cooling, refrigeration, air conditioning and electronics cooling. A numerical study is conducted to study the effects of using nanofluids on impinging slot jet over a flat plate with a ribbed surface. The main objective of the study was to investigate the possibility of improving the overall heat transfer rate by focusing on the improvements in the local and average surface Nusselt number values. Several parameters effects are studied including Solid Volume Fraction, Richardson number and Reynolds number. These results indicated a marked improvement in average Nusselt number with the increase in the solid volume fraction. Also, there is an amended value when the buoyancy effect is dominant over the whole domain. The results are shown in the form of streamlines, isotherms and Nusselt numbers contra other variables. The current work was simulated using a FORTRAN CFD Code, which discretizes the non-dimensional forms of the governing equations utilizing the finite volume method and solving the consequent algebraic equations using Gauss-Seidel method Utilizing TDMA.

  9. Performance Characterisation of a Hybrid Flat-Plate Vacuum Insulated Photovoltaic/Thermal Solar Power Module in Subtropical Climate

    Directory of Open Access Journals (Sweden)

    Andrew Y. A. Oyieke

    2016-01-01

    Full Text Available A flat-plate Vacuum Insulated Photovoltaic and Thermal (VIPV/T system has been thermodynamically simulated and experimentally evaluated to assess the thermal and electrical performance as well as energy conversion efficiencies under a subtropical climate. A simulation model made of specified components is developed in Transient Systems (TRNSYS environment into which numerical energy balance equations are implemented. The influence of vacuum insulation on the system’s electrical and thermal yields has been evaluated using temperatures, current, voltage, and power flows over daily and annual cycles under local meteorological conditions. The results from an experiment conducted under steady-state conditions in Durban, South Africa, are compared with the simulation based on the actual daily weather data. The VIPV/T has shown improved overall and thermal efficiencies of 9.5% and 16.8%, respectively, while electrical efficiency marginally reduced by 0.02% compared to the conventional PV/T. The simulated annual overall efficiency of 29% (i.e., 18% thermal and 11% electrical has been realised, in addition to the solar fraction, overall exergy, and primary energy saving efficiencies of 39%, 29%, and 27%, respectively.

  10. Numerical Investigation of Wall Cooling and Suction Effects on Supersonic Flat-Plate Boundary Layer Transition Using Large Eddy Simulation

    Directory of Open Access Journals (Sweden)

    Suozhu Wang

    2015-02-01

    Full Text Available Reducing friction resistance and aerodynamic heating has important engineering significance to improve the performances of super/hypersonic aircraft, so the purpose of transition control and turbulent drag reduction becomes one of the cutting edges in turbulence research. In order to investigate the influences of wall cooling and suction on the transition process and fully developed turbulence, the large eddy simulation of spatially evolving supersonic boundary layer transition over a flat-plate with freestream Mach number 4.5 at different wall temperature and suction intensity is performed in the present work. It is found that the wall cooling and suction are capable of changing the mean velocity profile within the boundary layer and improving the stability of the flow field, thus delaying the onset of the spatial transition process. The transition control will become more effective as the wall temperature decreases, while there is an optimal wall suction intensity under the given conditions. Moreover, the development of large-scale coherent structures can be suppressed effectively via wall cooling, but wall suction has no influence.

  11. Systematic Study of Separators in Air-Breathing Flat-Plate Microbial Fuel Cells—Part 2: Numerical Modeling

    Directory of Open Access Journals (Sweden)

    Sona Kazemi

    2016-01-01

    Full Text Available The separator plays a key role on the performance of passive air-breathing flat-plate MFCs (FPMFC as it isolates the anaerobic anode from the air-breathing cathode. The goal of the present work was to study the separator characteristics and its effect on the performance of passive air-breathing FPMFCs. This was performed partially through characterization of structure, properties, and performance correlations of eight separators presented in Part 1. Current work (Part 2 presents a numerical model developed based on the mixed potential theory to investigate the sensitivity of the electrode potentials and the power output to the separator characteristics. According to this numerical model, the decreased peak power results from an increase in the mass transfer coefficients of oxygen and ethanol, but mainly increasing mixed potentials at the anode by oxygen crossover. The model also indicates that the peak power is affected by the proton transport number of the separator, which affects the cathode pH. Anode pH, on the other hand, remains constant due to application of phosphate buffer solution as the electrolyte. Also according to this model, the peak power is not sensitive to the resistivity of the separator because of the overshadowing effect of the oxygen crossover.

  12. MHD boundary layer slip flow and radiative nonlinear heat transfer over a flat plate with variable fluid properties and thermophoresis

    Directory of Open Access Journals (Sweden)

    S.K. Parida

    2015-12-01

    Full Text Available This work considers the two-dimensional steady MHD boundary layer flow of heat and mass transfer over a flat plate with partial slip at the surface subjected to the convective heat flux. The particular attraction lies in searching the effects of variable viscosity and variable thermal diffusivity on the behavior of the flow. In addition, non-linear thermal radiation effects and thermophoresis are taken into account. The governing nonlinear partial differential equations for the flow, heat and mass transfer are transformed into a set of coupled nonlinear ordinary differential equations by using similarity variable, which are solved numerically by applying Runge–Kutta fourth–fifth order integration scheme in association with quasilinear shooting technique. The novel results for the dimensionless velocity, temperature, concentration and ambient Prandtl number within the boundary layer are displayed graphically for various parameters that characterize the flow. The local skin friction, Nusselt number and Sherwood number are shown graphically. The numerical results obtained for the particular case are fairly in good agreement with the result of Rahman [6].

  13. Further results on non-Newtonian power-law flows past a two-dimensional flat plate with finite length

    Energy Technology Data Exchange (ETDEWEB)

    Pantokartoras, Asterios [Democritus University of Thrace, Xanthi (Greece)

    2013-07-15

    The flow of a non-Newtonian, power-law fluid directed either tangentially or normally to a flat plate of finite length and infinite width (two-dimensional flow) is considered. The problem is investigated numerically using the code ANSYS FLUENT. This problem has been investigated in the past but only for shear-thinning fluids ( n < 1). We extend the investigation for the case of shear-thinning, Newtonian and shear-thickening fluids, covering a wide range of Reynolds numbers (from very low to very high). For low Reynolds numbers and low power-law index ( n < 0.6 ) the drag coefficient obeys the relationship C{sub D} = A/Re , both for tangential and normal flow. Equations for the quantity A have been derived as functions of the power-law index. For normal flow, the drag coefficient tends to become independent of the power-law index, both for shear-thinning and shear-thickening fluids at high Reynolds numbers.

  14. Surface pressures induced on a flat plate with in-line and side-by-side dual jet configurations

    Science.gov (United States)

    Schetz, J. A.; Jakubowski, A. K.; Aoyagi, K.

    1983-01-01

    A jet in a crossflow is of interest in numerous practical situations including jet-powered VTOL aircraft. Two aspects of the problem have received little prior study. First is the effect of the angle of the jet to the crossflow. Second is the performance of dual-jet configurations both in-line and side-by-side. The test plan for this work was designed to address these two aspects. The experiments were conducted in the 7 x 10 tunnel at NASA Ames at velocities from 14.5 - 35.8 m/sec (47.6 - 117.4 ft/sec.). Detailed pressure distributions are presented for single and dual jets over a range of velocity ratios from 3 to 8, spacings from 2 to 6 diameters and injection angles of 90, 75, and 105 degrees. The effects of the various parameters and the differences between the axisymmetric and flat plate geometries on the nature, size, shape, and strength of the interaction regions on the body surfaces are shown.

  15. SIMULATION OF SOLAR LITHIUM BROMIDE–WATER ABSORPTION COOLING SYSTEM WITH DOUBLE GLAZED FLAT PLATE COLLECTOR FOR ADRAR

    Directory of Open Access Journals (Sweden)

    ML CHOUGUI

    2014-12-01

    Full Text Available Adrar is a city in the Sahara desert, in southern Algeria known for its hot and dry climate, where a huge amount of energy is used for air conditioning. The aim of this research is to simulate a single effect lithium bromide–water absorption chiller coupled to a double-glazed flat plate collector to supply the cooling loads for a house of 200m2 in Adrar. The thermal energy is stored in an insulated thermal storage tank. The system was designed to cover a cooling load of 10.39KW for design day of July. Thermodynamic model was established to simulate the absorption cycle. The results have shown that the collector mass flow rate has a negligible effect on the minimum required collector area, but it has a significant effect on the optimum capacity of the storage tank. The minimum required collector area was about 65.3 m2, which could supply the cooling loads for the sunshine hours of the design day for July. The operation of the system has also been considered after sunset by saving solar energy.

  16. Natural Convection Flow of Fractional Nanofluids Over an Isothermal Vertical Plate with Thermal Radiation

    Directory of Open Access Journals (Sweden)

    Constantin Fetecau

    2017-03-01

    Full Text Available The studies of classical nanofluids are restricted to models described by partial differential equations of integer order, and the memory effects are ignored. Fractional nanofluids, modeled by differential equations with Caputo time derivatives, are able to describe the influence of memory on the nanofluid behavior. In the present paper, heat and mass transfer characteristics of two water-based fractional nanofluids, containing nanoparticles of CuO and Ag, over an infinite vertical plate with a uniform temperature and thermal radiation, are analytically and graphically studied. Closed form solutions are determined for the dimensionless temperature and velocity fields, and the corresponding Nusselt number and skin friction coefficient. These solutions, presented in equivalent forms in terms of the Wright function or its fractional derivatives, have also been reduced to the known solutions of ordinary nanofluids. The influence of the fractional parameter on the temperature, velocity, Nusselt number, and skin friction coefficient, is graphically underlined and discussed. The enhancement of heat transfer in the natural convection flows is lower for fractional nanofluids, in comparison to ordinary nanofluids. In both cases, the fluid temperature increases for increasing values of the nanoparticle volume fraction.

  17. Natural convection of nanofluids over a convectively heated vertical plate embedded in a porous medium

    Energy Technology Data Exchange (ETDEWEB)

    Ghalambaz, M.; Noghrehabadi, A.; Ghanbarzadeh, A., E-mail: m.ghalambaz@gmail.com, E-mail: ghanbarzadeh.a@scu.ac.ir [Department of Mechanical Engineering, Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of)

    2014-04-15

    In this paper, the natural convective flow of nanofluids over a convectively heated vertical plate in a saturated Darcy porous medium is studied numerically. The governing equations are transformed into a set of ordinary differential equations by using appropriate similarity variables, and they are numerically solved using the fourth-order Runge-Kutta method associated with the Gauss-Newton method. The effects of parametric variation of the Brownian motion parameter (Nb), thermophoresis parameter (Nt) and the convective heating parameter (Nc) on the boundary layer profiles are investigated. Furthermore, the variation of the reduced Nusselt number and reduced Sherwood number, as important parameters of heat and mass transfer, as a function of the Brownian motion, thermophoresis and convective heating parameters is discussed in detail. The results show that the thickness of the concentration profiles is much lower than the temperature and velocity profiles. For low values of the convective heating parameter (Nc), as the Brownian motion parameter increases, the non-dimensional wall temperature increases. However, for high values of Nc, the effect of the Brownian motion parameter on the non-dimensional wall temperature is not significant. As the Brownian motion parameter increases, the reduced Sherwood number increases and the reduced Nusselt number decreases. (author)

  18. Development of grooved flat-bar steels for the reaction plates of linear motor cars. Linear motor car yo reaction plate ''mizotsuki tokushu hirako'' no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, T.; Yamanaka, E.; Aso, K.; Ehiro, T.; Shiga, K.; Hayashi, H. (Kawasaki Steel Corp., Tokyo (Japan))

    1990-09-01

    In order to manufacture the reaction plates for linear motor cars, an anchor-bonding method which permit jointing of aluminum plates and steel plates was developed by the Kawasaki Steel jointly with the Kawasaki Heavy Industries. Though a hot forming of overhang grooves, with their opening narrower than their beds, on the steel plate surface has been considered virtually impossible, the new method called anchor-bonding was found out based on the investigation using a Plasticine model and hot-rolled steel models. By applying the method to commercial-scale mills, the flat bars having an overhang beyond 2.0mm were successfully obtained. With using a technology also established to control cross-sectional areas of both overhang groove and aluminum projection within a proper range, the resultant uniform filling of aluminum within the overhang grooves assured the manufacture of reaction plates with higher bonding. 6 refs., 20 figs., 4 tabs.

  19. Trans-iliosacral plating for vertically unstable fractures of sacral spine associated with spinopelvic dissociation: A cadaveric study.

    Science.gov (United States)

    Padalkar, Pravin; Pereira, Barry P; Kathare, Ambadas; Sun, Khong Kok; Kagda, Fareed; Joseph, Thambiah

    2012-05-01

    The treatment algorithm for sacral fracture associated with vertical shear pelvic fracture has not emerged. Our aim was to study a new approach of fixation for comminuted and vertically unstable fracture pattern with spinopelvic dissociation to overcome inconsistent outcome and avoid complications associated with fixations. We propose fixation with well-contoured thick reconstruction plate spreading across sacrum from one iliac bone to another with fixation points in iliac wing, sacral ala and sacral pedicle on either side. Present biomechanical study tests the four fixation pattern to compare their stiffness to vertical compressive forces. Dissection was performed on human cadavers through posterior midline paraspinal approach elevating erector spinae from insertion with two flaps. Feasibility of surgical exposure and placement of contoured plate for fixation was evaluated. Ten age and sex matched computed tomography scans of pelvis with both hips were obtained. Reconstructions were performed with advantage windows 4.2 (GE Light Speed QX/I, General Electric, Milwaukee, WI, USA). Using the annotation tools, direct digital CT measurement (0.6 mm increments) of three linear parameters was carried out. Readings were recorded at S2 sacral level. Pelvic CT scans were extensively studied for entry point, trajectory and estimated length for screw placement in S2 pedicle, sacral ala and iliac wing. Readings were recorded for desired angulation of screw in iliac wing ala of sacrum and sacral pedicle with respect to midline. The readings were analyzed by the values of mean and standard deviation. Biomechanical efficacy of fixation methods was studied separately on synthetic bone. Four fixation patterns given below were tested to compare their stiffness to vertical compressive forces: 1) Single S1 iliosacral screw (7.5 mm cancellous screw), 2) Two S1 and S2 iliosacral screws, 3) Isolated trans-iliosacral plate, 4) Trans-iliosacral plate + single S1 iliosacral screw. Mean of

  20. Modelling and control of Base Plate Loading subsystem for The Motorized Adjustable Vertical Platform

    Science.gov (United States)

    Norsahperi, N. M. H.; Ahmad, S.; Fuad, A. F. M.; Mahmood, I. A.; Toha, S. F.; Akmeliawati, R.; Darsivan, F. J.

    2017-03-01

    Malaysia National Space Agency, ANGKASA is an organization that intensively undergoes many researches especially on space. On 2011, ANGKASA had built Satellite Assembly, Integration and Test Centre (AITC) for spacecraft development and test. Satellite will undergo numerous tests and one of it is Thermal test in Thermal Vacuum Chamber (TVC). In fact, TVC is located in cleanroom and on a platform. The only available facilities for loading and unloading the satellite is overhead crane. By utilizing the overhead crane can jeopardize the safety of the satellite. Therefore, Motorized vertical platform (MAVeP) for transferring the satellite into the TVC with capability to operate under cleanroom condition and limited space is proposed to facilitate the test. MAVeP is the combination of several mechanisms to produce horizontal and vertical motions with the ability to transfer the satellite from loading bay into TVC. The integration of both motions to elevate and transfer heavy loads with high precision capability will deliver major contributions in various industries such as aerospace and automotive. Base plate subsystem is capable to translate the horizontal motion by converting the angular motion from motor to linear motion by using rack and pinion mechanism. Generally a system can be modelled by performing physical modelling from schematic diagram or through system identification techniques. Both techniques are time consuming and required comprehensive understanding about the system, which may expose to error prone especially for complex mechanism. Therefore, a 3D virtual modelling technique has been implemented to represent the system in real world environment i.e. gravity to simulate control performance. The main purpose of this technique is to provide better model to analyse the system performance and capable to evaluate the dynamic behaviour of the system with visualization of the system performance, where a 3D prototype was designed and assembled in Solidworks

  1. Validation of a simple dynamic thermal performance characterization model based on the piston flow concept for flat-plate solar collectors

    DEFF Research Database (Denmark)

    Deng, Jie; Yang, Ming; Ma, Rongjiang

    2016-01-01

    . (2012) for the model turns out to be the collector static response time constant τC by analytical derivation. The nonlinear least squares method is applied to determine the characteristic parameters of a flat-plate solar air collector previously tested by the authors. Then the obtained parameters...... al. (2016a) is also considered. The results show that the prediction performance of the simple dynamic model is nearly as accurate as the ODE numerical solution and the TIM by Deng et al. (2016a) except some special conditions such as sharply changed solar irradiance and collector inlet temperature.......A simple dynamic characterization model of flat-plate solar collectors based on the piston flow concept is used both to identify the collector characteristic parameters and to predict the dynamic thermal performance. The heat transport time originally defined as (1 − e−1)−1τC by Amrizal et al...

  2. Numerical Investigation of Laminar Diffusion Flames Established on a Horizontal Flat Plate in a Parallel Air Stream

    Directory of Open Access Journals (Sweden)

    E. D. Gopalakrishnan

    2011-06-01

    Full Text Available Numerical investigation of laminar diffusion flames established on a flat plate in a parallel air stream is presented. A numerical model with a multi-step chemical kinetics mechanism, variable thermo-physical properties, multi-component species diffusion and a radiation sub-model is employed for this purpose. Both upward and downward injection of fuel has been considered in a normal gravity environment. The thermal and aerodynamic structure of the flame has been explained with the help of temperature and species contours, net reaction rate of fuel and streamlines. Flame characteristics and stability aspects for several air and fuel velocity combinations have been studied. An important characteristic of a laminar boundary layer diffusion flame with upward injection of fuel is the velocity overshoot that occurs near the flame zone. This is not observed when the fuel is injected in the downward direction. The flame standoff distance is slightly higher for the downward injection of fuel due to increase in displacement thickness of boundary layer. Influence of an obstacle, namely the backward facing step, on the flame characteristics and stability aspects is also investigated. Effects of air and fuel velocities, size and location of the step are studied in detail. Based on the air and fuel velocities, different types of flames are predicted. The use of a backward-facing step as a flame holding mechanism for upward injection of fuel, results in increased stability limits due to the formation of a recirculation zone behind the step. The predicted stability limits match with experimentally observed limits. The step location is seen to play a more important role as compared to the step height in influencing the stability aspects of flames.

  3. The Effect of the Angle of Inclination on the Efficiency in a Medium-Temperature Flat Plate Solar Collector

    Directory of Open Access Journals (Sweden)

    Orlando Montoya-Marquez

    2017-01-01

    Full Text Available In this experimental work, the effects of the inclination angle β and the (Ti − Ta/G on the efficiency and the UL-value were investigated on a medium-temperature flat plate solar collector. The experiments were based on steady-state energy balance, by heat flow calorimetry at indoor conditions and considering the standard American National Standard Institute/American Society of Heating Refrigerating and Air Conditioning Engineers (ANSI/ASHRAE 93-2010. The solar radiation was emulated by the Joule effect using a proportional integral derivative (PID control considering two conditions of the absorber temperature, Case 1: (To − Ti > 0, and Case 2: (To − Ti = 0. The inclination angles were 0°–90° and the (Ti − Ta/G were 0.044–0.083 m2·°C/W and 0.124–0.235 for Case 1 and Case 2, respectively. The variations of β and (Ti − Ta/G cause efficiency changes up to 0.37–0.45 (21.6% and 0.31–0.45 (45.0%, respectively, for Case 1. Also, the UL(β reached changes up to 10.1–12.0 W/m2·°C (19.2% and 8.4–12.0 W/m2·°C (41.7%, respectively, for Case 1. The most significant changes of UL(β/UL(90° vs. β were 8.0% at the horizontal position for Case 1, while for Case 2, the maximum change was 1.8% only. Therefore, the changes of the inclination angle cause significant variations of the convective flow patterns within the collector, which leads to considerable variation of the collector efficiency and its UL value.

  4. Diseño de un colector solar de placa plana; Design of a Solar Flat Plate Collector

    Directory of Open Access Journals (Sweden)

    Jeovany Rafael Rodríguez Mejía

    2015-12-01

    Full Text Available En el presente artículo se integra el uso de un software de diseño mecánico y un algoritmo de simulación de la operación de un colector solar de placa plana, con el objetivo de simplificar el proceso de diseño y manufactura de este último. Se exponen los resultados de la simulación de la operación del colector solar considerando diferentes combinaciones en los parámetros de los materiales utilizados, tales como sus propiedades y características físico químicas, además de la variación de las dimensiones del sistema adiseñar. Finalmente en el artículo se evalúa la operación de un colector solar para las condiciones climatológicas típicas de la irradiancia, velocidad de viento y temperatura ambiente a partir de una serie de curvas sinusoidales, típicas de Cuba, validándose la viabilidad del algoritmo como apoyo en la etapa de diseño y selección de materiales.In this article the use of mechanical design software and an algorithm for simulating the operation of a flat plate solar collector, with the objective of simplifying the process of design and manufacture of the latter isintegrated. The simulation results of the operation of the solar collector considering different combinations in the parameters of the materials used, such as its physicochemical properties and features in addition to thevariation of the dimensions of the system design are set. The article finally evaluates the operation of a solar collector for typical climatic conditions of irradiance, wind speed and ambient temperature from a series ofsinusoidal, typical Cuba curves is evaluated, validating the feasibility of the algorithm as support in step design and material selection.

  5. Thermal protection system gap heating rates of the Rockwell International flat plate heat transfer model (OH2A/OH2B)

    Science.gov (United States)

    Foster, T. F.; Lockman, W. K.; Grifall, W. J.

    1973-01-01

    Heat transfer data for the Rockwell International Flat Plate Thermocouple Model are presented. The model simulated the Space Shuttle Vehicle Thermal Protection System. Data were recorded for locations in and around various size gaps for various gap orientation configurations. The test was conducted at Mach 5.1 for free-stream Reynolds number per foot values from 500,000 to 1,500,000.

  6. An Experimental Study on the Solidification and Melting of Water around a Vertical Heat Transfer Plate with Pin Fins

    OpenAIRE

    平澤, 良男; 陳, 東; 渡邉, 弘毅; 竹越, 栄俊

    1997-01-01

    In the present study, the solidification and melting of water were investigated experimentally for the case of a vertical heat transfer plate with pin fins. In the experiment, temperature distributions, ice and water volume fractions, and heat flux changes were measured and the flow patterns in the water were observed for examination of the phase change process. In the solidification, the phase change rate increased monotonously with increasing number of fins. In the melting, the temperature ...

  7. Radiation and mass transfer effects on unsteady MHD convective flow past an infinite vertical plate with Dufour and Soret effects

    OpenAIRE

    N. Vedavathi; K Ramakrishna; K. Jayarami Reddy

    2015-01-01

    This paper deals with the effects of heat and mass transfer on two-dimensional unsteady MHD free convection flow past a vertical porous plate in a porous medium in the presence of thermal radiation under the influence of Dufour and Soret effects. The governing nonlinear partial differential equations have been reduced to the coupled nonlinear ordinary differential equations by the similarity transformations. The resulting equations are then solved numerically using shooting method along with ...

  8. Oscillatory free-convective flow of an elastico-viscous fluid past an impulsively started infinite vertical porous plate. II

    Science.gov (United States)

    Singh, A. K.

    1984-10-01

    The author presents the two-dimensional free-convective flow of an elastico-viscous fluid past an infinite vertical porous plate for the Stokes problem when the flow is subjected to a constant suction velocity through the porous plate. As the mean steady flow has been presented in Part I, only the solution for the transient velocity profiles, transient temperature profiles, the amplitude and the phase of the skin-friction and the rate of heat transfer are presented in this work. As in the case of mean steady flow, the influence of various parameters on the unsteady flow field is discussed for both the cases cooling and heating of the porous plate by free-convection currents.

  9. Effects of Hall current, radiation and rotation on natural convection heat and mass transfer flow past a moving vertical plate

    Directory of Open Access Journals (Sweden)

    G.S. Seth

    2014-06-01

    Full Text Available An investigation of the effects of Hall current and rotation on unsteady hydromagnetic natural convection flow with heat and mass transfer of an electrically conducting, viscous, incompressible and optically thick radiating fluid past an impulsively moving vertical plate embedded in a fluid saturated porous medium, when temperature of the plate has a temporarily ramped profile, is carried out. Exact solution of the governing equations is obtained in closed form by Laplace transform technique. Exact solution is also obtained in case of unit Schmidt number. Expressions for skin friction due to primary and secondary flows and Nusselt number are derived for both ramped temperature and isothermal plates. Expression for Sherwood number is also derived. The numerical values of primary and secondary fluid velocities, fluid temperature and species concentration are displayed graphically whereas those of skin friction are presented in tabular form for various values of pertinent flow parameters.

  10. Vertical migratory rhythms of benthic diatoms in a tropical intertidal sand flat: Influence of irradiance and tides

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Anil, A.C.

    Vertical migratory behavior of benthic diatoms is one of the adaptive strategies employed for a life in intertidal habitats. Irradiance and tides are considered to be the key factors governing vertical migration. Experiments were carried out...

  11. Attempts of Thermal Imaging Camera Usage in Estimations of the Convective Heat Loss From a Vertical Plate

    Directory of Open Access Journals (Sweden)

    Denda Hubert

    2014-01-01

    Full Text Available In this paper a new method for determining heat transfer coefficients using a gradient method has been developed. To verify accuracy of the proposed method vertical isothermal heating plate with natural convection mechanism has been examined. This configuration was deliberately chosen, because of the fact that such case is historically the earliest and most thoroughly studied and its rich scientific documentation – the most reliable. New method is based on temperature field visualization made in perpendicular plane to the heating surface of the plate using infrared camera. Because the camera does not record temperature of air itself but the surface only, therefore plastic mesh with low thermal conductivity has been used as a detector. Temperature of each mesh cell, placed perpendicular to the vertical heating surface and rinsed with convection stream of heated air could be already recorded by infrared camera. In the same time using IR camera surface of heating plate has been measured. By numerical processing of the results matrix temperature gradient on the surface ∂T/∂x │ x=0, local heat transfer coefficients αy, and local values of Nusselt number Nuy, can be calculated. After integration the average Nusselt number for entire plate can be calculated. Obtained relation characteristic numbers Nu = 0.647 Ra 0.236 (R2 = 0.943, has a good correlation with literature reports and proves usefulness of the method.

  12. MHD forced convective laminar boundary layer flow from a convectively heated moving vertical plate with radiation and transpiration effect.

    Science.gov (United States)

    Uddin, Md Jashim; Khan, Waqar A; Ismail, A I Md

    2013-01-01

    A two-dimensional steady forced convective flow of a Newtonian fluid past a convectively heated permeable vertically moving plate in the presence of a variable magnetic field and radiation effect has been investigated numerically. The plate moves either in assisting or opposing direction to the free stream. The plate and free stream velocities are considered to be proportional to x(m) whilst the magnetic field and mass transfer velocity are taken to be proportional to x((m-1)/2) where x is the distance along the plate from the leading edge of the plate. Instead of using existing similarity transformations, we use a linear group of transformations to transform the governing equations into similarity equations with relevant boundary conditions. Numerical solutions of the similarity equations are presented to show the effects of the controlling parameters on the dimensionless velocity, temperature and concentration profiles as well as on the friction factor, rate of heat and mass transfer. It is found that the rate of heat transfer elevates with the mass transfer velocity, convective heat transfer, Prandtl number, velocity ratio and the magnetic field parameters. It is also found that the rate of mass transfer enhances with the mass transfer velocity, velocity ratio, power law index and the Schmidt number, whilst it suppresses with the magnetic field parameter. Our results are compared with the results existing in the open literature. The comparisons are satisfactory.

  13. Ionospheric plasma flow about a system of electrically biased flat plates. M.S. Thesis - Cleveland State Univ. Final Report

    Science.gov (United States)

    Herr, Joel L.

    1993-01-01

    The steady state interaction of two electrically biased parallel plates immersed in a flowing plasma characteristic of low earth orbit is studied numerically. Fluid equations are developed to describe the motion of the cold positively charged plasma ions, and are solved using finite-differences in two dimensions on a Cartesian grid. The behavior of the plasma electrons is assumed to be described by the Maxwell-Boltzmann distribution. Results are compared to an analytical and a particle simulation technique for a simplified flow geometry consisting of a single semi-infinite negatively biased plate. Comparison of the extent of the electrical disturbance into the flowing plasma and the magnitude of the current collected by the plate is very good. The interaction of two equally biased parallel plates is studied as a function of applied potential. The separation distance at which the current collected by either plate decreases by five and twenty percent is determined as a function of applied potential. The percent decreases were based on a non-interacting case. The decrease in overall current is caused by a decrease in ionic density in the region between the plates. As the separation between the plates decreases, the plates collect the ions at a faster rate than they are supplied to the middle region by the oncoming plasma flow. The docking of spacecraft in orbit is simulated by moving two plates of unequal potential toward one another in a quasi-static manner. One plate is held at a large negative potential while the other floats electrically in the resulting potential field. It is found that the floating plate does not charge continuously negative as it approaches the other more negatively biased plate. Instead, it charges more and then less negative as ionic current decreases and then increases respectively upon approach. When the two plates come into contact, it is expected that the electrically floating plate will charge rapidly negative to a potential near that of

  14. Rotation and Radiation Effects on MHD Flow through Porous Medium Past a Vertical Plate with Heat and Mass Transfer

    Directory of Open Access Journals (Sweden)

    Uday Singh Rajput

    2017-11-01

    Full Text Available Effects of rotation and radiation on unsteady MHD flow past a vertical plate with variable wall temperature and mass diffusion in the presence of Hall current is studied here. Earlier we studied chemical reaction effect on unsteady MHD flow past an exponentially accelerated inclined plate with variable temperature and mass diffusion in the presence of Hall current. We had obtained the results which were in agreement with the desired flow phenomenon. To study further, we are changing the model by considering radiation effect on fluid, and changing the geometry of the model. Here in this paper we are taking the plate positioned vertically upward and rotating with velocity Ω . Further, medium of the flow is taken as porous. The plate temperature and the concentration level near the plate increase linearly with time. The governing system of partial differential equations is transformed to dimensionless equations using dimensionless variables. The dimensionless equations under consideration have been solved by Laplace transform technique. The model contains equations of motion, diffusion equation and equation of energy. To analyze the solution of the model, desirable sets of the values of the parameters have been considered. The governing equations involved in the flow model are solved by the Laplace-transform technique. The results obtained have been analyzed with the help of graphs drawn for different parameters. The numerical values obtained for the drag at boundary and Nusselt number have been tabulated. We found that the values obtained for velocity, concentration and temperature are in concurrence with the actual flow of the fluid

  15. 78 FR 75371 - Diffusion-Annealed, Nickel-Plated Flat-Rolled Steel Products From Japan; Scheduling of the Final...

    Science.gov (United States)

    2013-12-11

    ... defined the subject merchandise as flat-rolled, cold reduced steel products, regardless of chemistry... Commission's Handbook on E-Filing, available on the Commission's Web site at http://edis.usitc.gov...

  16. Forces and Moments on Flat Plates of Small Aspect Ratio with Application to PV Wind Loads and Small Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Xavier Ortiz

    2015-03-01

    Full Text Available To improve knowledge of the wind loads on photovoltaic structures mounted on flat roofs at the high angles required in high latitudes, and to study starting flow on low aspect ratio wind turbine blades, a series of wind tunnel tests were undertaken. Thin flat plates of aspect ratios between 0.4 and 9.0 were mounted on a sensitive three-component instantaneous force and moment sensor. The Reynolds numbers varied from 6 × 104 to 2 × 105. Measurements were made for angles of attack between 0° and 90° both in the free stream and in wall proximity with increased turbulence and mean shear. The ratio of drag to lift closely follows the inverse tangent of the angle of incidence for virtually all measurements. This implies that the forces of interest are due largely to the instantaneous pressure distribution around the plate and are not significantly influenced by shear stresses. The instantaneous forces appear most complex for the smaller aspect ratios but the intensity of the normal force fluctuations is between 10% and 20% in the free-steam but can exceed 30% near the wall. As the wind tunnel floor is approached, the lift and drag reduce with increasing aspect ratio, and there is a reduction in the high frequency components of the forces. It is shown that the centre of pressure is closer to the centre of the plates than the quarter-chord position for nearly all cases.

  17. A proposal on Correction of the Data obtained by Pressure Transducer Fitted on Vibratory Flat Plate in Water

    OpenAIRE

    黒部, 雄三; 吉田, 三雄; Yuzo, KUROBE; Mitsuo, YOSHIDA; 運輸省船舶技術研究所推進性能部

    1985-01-01

    The pressure fluctuations induced by marine propellers are usually measured by means of pressure transducers fitted on hull plate or the local plate of ocean structure. In such a case the pressure transducers are oscillated with the plate, so the measured pressure fluctuations would be shifted from the real pressure fluctuations. If these vibrations are excessive, the effect of vibrations on the measured pressure fluctuations should be corrected. In this paper, as one of the simple cases the ...

  18. Experimental Investigation of a Solar Greenhouse Heating System Equipped with a Parabolic Trough Solar Concentrator and a Double-Purpose Flat Plate Solar Collector

    Directory of Open Access Journals (Sweden)

    M Jafari

    2017-10-01

    Full Text Available Introduction Greenhouses provide a suitable environment in which all the parameters required for growing the plants can be controlled throughout the year. Greenhouse heating is one of the most important issues in productivity of a greenhouse. In many countries, heating costs in the greenhouses are very high, having almost 60-80% of the total production costs. In recent years, several studies have attempted to reduce the heating costs of the greenhouses by applying more energy efficient equipment and using the renewable energy sources as alternatives or supplementary to the fossil fuels. In the present study a novel solar greenhouse heating system equipped with a parabolic trough solar concentrator (PTC and a flat-plate solar collector has been developed. Therefore, the aim of this paper is to investigate the performance of the proposed heating system at different working conditions. Materials and Methods The presented solar greenhouse heating system was comprised of a parabolic trough solar concentrator (PTC, a heat storage tank, a pump and a flat plate solar collector. The PTC was constructed from a polished stainless steel sheet (as the reflector and a vacuum tube receiver. The PTC was connected to the tank by using insulated tubes and a water pump was utilized to circulate the working fluid trough the PTC and the heat exchanger installed between walls of the tank. The uncovered solar collector was located inside the greenhouse. During the sunshine time, a fraction of the total solar radiation received inside the greenhouse is absorbed by the solar collector. This rises the temperature of the working fluid inside the collector which led to density reduction and natural flow of the fluid. In other words, the collector works as a natural flow flat plate solar collector during the sunshine time. At night, when the greenhouse temperature is lower than tank temperature, the fluid flows in a reverse direction through the solar collector and the

  19. Radiation effects on unsteady MHD convective heat and mass transfer past a vertical plate with chemical reaction and viscous dissipation

    Directory of Open Access Journals (Sweden)

    Chandra Shekar Balla

    2015-09-01

    Full Text Available A numerical analysis is performed to study the unsteady magnetohydrodynamic convective flow of heat and mass transfer of a viscous, incompressible, electrically conducting Newtonian fluid along a vertical permeable plate in the presence of a homogeneous first order chemical reaction and taking into account thermal radiation effects. The porous plate was subjected to a constant suction velocity with variable surface temperature and concentration. The governing coupled non-linear boundary layer partial differential equations were solved by an efficient and unconditionally stable finite element method based on Galerkin weighted residual approach. A representative set of computational results for the velocity, temperature and concentration profiles as well as Local skin-friction coefficient, Local Nusselt number and Local Sherwood number are presented graphically for various governing parameters such as M,R,Ec,Sc,andK. In the present analysis various comparisons with previously published work are performed and the results are found to be in a good agreement.

  20. Free convection flow of some fractional nanofluids over a moving vertical plate with uniform heat flux and heat source

    Science.gov (United States)

    Azhar, Waqas Ali; Vieru, Dumitru; Fetecau, Constantin

    2017-08-01

    Free convection flow of some water based fractional nanofluids over a moving infinite vertical plate with uniform heat flux and heat source is analytically and graphically studied. Exact solutions for dimensionless temperature and velocity fields, Nusselt numbers, and skin friction coefficients are established in integral form in terms of modified Bessel functions of the first kind. These solutions satisfy all imposed initial and boundary conditions and reduce to the similar solutions for ordinary nanofluids when the fractional parameters tend to one. Furthermore, they reduce to the known solutions from the literature when the plate is fixed and the heat source is absent. The influence of fractional parameters on heat transfer and fluid motion is graphically underlined and discussed. The enhancement of heat transfer in such flows is higher for fractional nanofluids in comparison with ordinary nanofluids. Moreover, the use of fractional models allows us to choose the fractional parameters in order to get a very good agreement between experimental and theoretical results.

  1. Experimental Optimization of Passive Cooling of a Heat Source Array Flush-Mounted on a Vertical Plate

    Directory of Open Access Journals (Sweden)

    Antoine Baudoin

    2016-11-01

    Full Text Available Heat sources, such as power electronics for offshore power, could be cooled passively—mainly by conduction and natural convection. The obvious advantage of this strategy is its high reliability. However, it must be implemented in an efficient manner (i.e., the area needs to be kept low to limit the construction costs. In this study, the placement of multiple heat sources mounted on a vertical plate was studied experimentally for optimization purposes. We chose a regular distribution, as this is likely to be the preferred choice in the construction process. We found that optimal spacing can be determined for a targeted source density by tuning the vertical and horizontal spacing between the heat sources. The optimal aspect ratio was estimated to be around two.

  2. Closed form solutions for unsteady free convection flow of a second grade fluid over an oscillating vertical plate.

    Directory of Open Access Journals (Sweden)

    Farhad Ali

    Full Text Available Closed form solutions for unsteady free convection flows of a second grade fluid near an isothermal vertical plate oscillating in its plane using the Laplace transform technique are established. Expressions for velocity and temperature are obtained and displayed graphically for different values of Prandtl number Pr, thermal Grashof number Gr, viscoelastic parameter α, phase angle ωτ and time τ. Numerical values of skin friction τ 0 and Nusselt number Nu are shown in tables. Some well-known solutions in literature are reduced as the limiting cases of the present solutions.

  3. Electricity from photovoltaic solar cells. Flat-Plate Solar Array Project of the US Department of Energy's National Photovoltaics Program: 10 years of progress

    Science.gov (United States)

    Christensen, Elmer

    1985-01-01

    The objectives were to develop the flat-plate photovoltaic (PV) array technologies required for large-scale terrestrial use late in the 1980s and in the 1990s; advance crystalline silicon PV technologies; develop the technologies required to convert thin-film PV research results into viable module and array technology; and to stimulate transfer of knowledge of advanced PV materials, solar cells, modules, and arrays to the PV community. Progress reached on attaining these goals, along with future recommendations are discussed.

  4. Charts Adapted from Van Driest's Turbulent Flat-plate Theory for Determining Values of Turbulent Aerodynamic Friction and Heat-transfer Coefficients

    Science.gov (United States)

    Lee, Dorothy B; Faget, Maxime A

    1956-01-01

    A modified method of Van Driest's flat-plate theory for turbulent boundary layer has been found to simplify the calculation of local skin-friction coefficients which, in turn, have made it possible to obtain through Reynolds analogy theoretical turbulent heat-transfer coefficients in the form of Stanton number. A general formula is given and charts are presented from which the modified method can be solved for Mach numbers 1.0 to 12.0, temperature ratios 0.2 to 6.0, and Reynolds numbers 0.2 times 10 to the 6th power to 200 times 10 to the 6th power.

  5. Three-Dimensional Thermal Boundary Layer Corrections for Circular Heat Flux Gauges Mounted in a Flat Plate with a Surface Temperature Discontinuity

    Science.gov (United States)

    Kandula, M.; Haddad, G. F.; Chen, R.-H.

    2006-01-01

    Three-dimensional Navier-Stokes computational fluid dynamics (CFD) analysis has been performed in an effort to determine thermal boundary layer correction factors for circular convective heat flux gauges (such as Schmidt-Boelter and plug type)mounted flush in a flat plate subjected to a stepwise surface temperature discontinuity. Turbulent flow solutions with temperature-dependent properties are obtained for a free stream Reynolds number of 1E6, and freestream Mach numbers of 2 and 4. The effect of gauge diameter and the plate surface temperature have been investigated. The 3-D CFD results for the heat flux correction factors are compared to quasi-21) results deduced from constant property integral solutions and also 2-D CFD analysis with both constant and variable properties. The role of three-dimensionality and of property variations on the heat flux correction factors has been demonstrated.

  6. Flat sources for active acoustic shielding based on distributed control of a vibrating plate coupled with a thin cavity

    OpenAIRE

    Berkhoff, Arthur P.; Ho, J.

    2013-01-01

    Air cavities between plates are often used to improve noise insulation by passive means, especially at high frequencies. Such configurations may suffer from resonances, such as due to the mass-air-mass resonance. Lightweight structures, which tend to be undamped, may suffer from structural resonances as well. Active methods have been suggested for improved noise insulation of plates, using piezoelectric patch actuators or inertial mass actuators. Other active methods for improved noise insula...

  7. Critical Heat Flux on a Flat Plate Located at the Middle of a Duct in Forced Flow of Pressurized He II

    Science.gov (United States)

    Okamura, T.; Saeki, M.; Hata, K.; Hama, K.; Shirai, Y.; Shiotsu, M.

    2004-06-01

    Critical heat fluxes (CHFs) were measured on two horizontal flat plate heaters 6 mm wide and 20 mm long located on inner upper and lower walls of a rectangular duct at 50 mm from the inlet. The duct has 3 mm × 20 mm inner cross sectional area and 100 mm length. The flat plate heaters are made of Manganin and connected electrically in series. Therefore, the ratio of the cross-sectional area of duct to the heater area is 0.25. The measurements were made for the flow velocities from 0 m/s to 2.1 m/s and for the inlet liquid temperatures of 1.6 K, 1.8 K, 1.9 K, 2.0 K and 2.1 K. The measured CHFs were higher for larger flow velocity and lower liquid temperature. The equation of CHF for the forced convection was derived based on two fluid model, ordinary convection theorem and experimental results. It was confirmed that this correlation can describe not only the author's data on the duct but also other worker's data for channels with different shapes and sizes.

  8. Experimental determination of new statistical correlations for the calculation of the heat transfer coefficient by convection for flat plates, cylinders and tube banks

    Directory of Open Access Journals (Sweden)

    Ismael Fernando Meza Castro

    2017-07-01

    Full Text Available Introduction: This project carried out an experimental research with the design, assembly, and commissioning of a convection heat transfer test bench. Objective: To determine new statistical correlations that allow knowing the heat transfer coefficients by air convection with greater accuracy in applications with different heating geometry configurations. Methodology: Three geometric configurations, such as flat plate, cylinders and tube banks were studied according to their physical properties through Reynolds and Prandtl numbers, using a data transmission interface using Arduino® controllers Measured the air temperature through the duct to obtain real-time data and to relate the heat transferred from the heating element to the fluid and to perform mathematical modeling in specialized statistical software. The study was made for the three geometries mentioned, one power per heating element and two air velocities with 10 repetitions. Results: Three mathematical correlations were obtained with regression coefficients greater than 0.972, one for each heating element, obtaining prediction errors in the heat transfer convective coefficients of 7.50% for the flat plate, 2.85% for the plate Cylindrical and 1.57% for the tube bank. Conclusions: It was observed that in geometries constituted by several individual elements, a much more accurate statistical adjustment was obtained to predict the behavior of the convection heat coefficients, since each unit reaches a stability in the surface temperature profile with Greater speed, giving the geometry in general, a more precise measurement of the parameters that govern the transfer of heat, as it is in the case of the geometry of the tube bank.

  9. Effect of openings collectors and solar irradiance on the thermal efficiency of flat plate-finned collector for indirect-type passive solar dryer

    Science.gov (United States)

    Batubara, Fatimah; Dina, Sari Farah; Klaudia Kathryn Y., M.; Turmuzi, M.; Siregar, Fitri; Panjaitan, Nora

    2017-06-01

    Research on the effect of openings solar collector and solar irradiance to thermal efficiency has been done. Solar collector by flat plate-finned type consists of 3 ply insulator namely wood, Styrofoam and Rockwool with thickness respectively are 10 mm, 25 mm and 50 mm. Absorber plate made of aluminum sheet with thickness of 0.30 mm, painted by black-doff. Installation of 19 units fins (length x height x thickness: 1000x20x10 mm) on the collector will increase surface area of absorber so it can receive much more solar energy. The solar collector cover is made of glass (thickness of 5 mm). During the research, the solar irradiance and temperature of collector are measured and recorded every five minutes. Temperature measurement performed on the surface of the absorber plate, inside of collector, surface cover and the outer side insulator (plywood). This data is used to calculate the heat loss due to conduction, convection and radiation on the collector. Openings of collectors vary as follows: 100%, 75%, 15% and 0% (total enclosed). The data collecting was conducted from 09.00 am to 17.00 pm and triplicates. The collector thermal efficiency calculated based on the ratio of the amount of heat received to the solar irradiance absorbed. The results show that each of openings solar collector has different solar irradiance (because it was done on a different day) which is in units of W/m2: 390 (100% open), 376 (75% open), 429 (15% open), and 359 (totally enclosed). The highest thermal efficiency is in openings variation of 15% opened. These results indicate that the efficiency of the collector is influenced by the solar irradiance received by the collector and the temperature on the collector plate. The highest thermal efficiency is in variation of openings 15%. These indicate that the efficiency of the collector was influenced by solar irradiance received by the collector and openings of the collector plate.

  10. Flat sources for active acoustic shielding based on distributed control of a vibrating plate coupled with a thin cavity

    NARCIS (Netherlands)

    Berkhoff, A.P.; Ho, J.H.

    2013-01-01

    Air cavities between plates are often used to improve noise insulation by passive means, especially at high frequencies. Such configurations may suffer from resonances, such as due to the mass-air-mass resonance. Lightweight structures, which tend to be undamped, may suffer from structural

  11. Boundary layer flow adjacent to a permeable vertical plate with constant surface temperature

    Science.gov (United States)

    Najib, Najwa; Bachok, Norfifah; Md Arifin, Norihan

    2013-04-01

    The effects of suction/injection on the laminar boundary layer flow adjacent to a vertical wall with constant surface temperature are considered. The governing partial differential equations are first transformed into ordinary differential equations before being solved numerically by a finite difference method. Results for the skin friction coefficient, local Nusselt number, velocity profiles as well as temperature profiles are presented for different values of the governing parameters. It is found that the solution was unique for the assisting flow, while dual solutions exist for the opposing flow. The results indicate that the range of known dual solutions increases with suction and decreases with injection.

  12. Radiation and mass transfer effects on unsteady MHD convective flow past an infinite vertical plate with Dufour and Soret effects

    Directory of Open Access Journals (Sweden)

    N. Vedavathi

    2015-03-01

    Full Text Available This paper deals with the effects of heat and mass transfer on two-dimensional unsteady MHD free convection flow past a vertical porous plate in a porous medium in the presence of thermal radiation under the influence of Dufour and Soret effects. The governing nonlinear partial differential equations have been reduced to the coupled nonlinear ordinary differential equations by the similarity transformations. The resulting equations are then solved numerically using shooting method along with Runge–Kutta fourth order integration scheme. The numerical results are displayed graphically showing the effects of various parameters entering into the problem. Finally, the local values of the skin-friction coefficient, Nusselt number and Sherwood number are also shown in tabular form.

  13. Exact Solutions for Unsteady Free Convection Flow of Casson Fluid over an Oscillating Vertical Plate with Constant Wall Temperature

    Directory of Open Access Journals (Sweden)

    Asma Khalid

    2015-01-01

    Full Text Available The unsteady free flow of a Casson fluid past an oscillating vertical plate with constant wall temperature has been studied. The Casson fluid model is used to distinguish the non-Newtonian fluid behaviour. The governing partial differential equations corresponding to the momentum and energy equations are transformed into linear ordinary differential equations by using nondimensional variables. Laplace transform method is used to find the exact solutions of these equations. Expressions for shear stress in terms of skin friction and the rate of heat transfer in terms of Nusselt number are also obtained. Numerical results of velocity and temperature profiles with various values of embedded flow parameters are shown graphically and their effects are discussed in detail.

  14. Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

    Science.gov (United States)

    Hussanan, Abid; Zuki Salleh, Mohd; Tahar, Razman Mat; Khan, Ilyas

    2014-01-01

    In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

  15. Thermal radiation and mass transfer effects on unsteady MHD free convection flow past a vertical oscillating plate

    Science.gov (United States)

    Rana, B. M. Jewel; Ahmed, Rubel; Ahmmed, S. F.

    2017-06-01

    Unsteady MHD free convection flow past a vertical porous plate in porous medium with radiation, diffusion thermo, thermal diffusion and heat source are analyzed. The governing non-linear, partial differential equations are transformed into dimensionless by using non-dimensional quantities. Then the resultant dimensionless equations are solved numerically by applying an efficient, accurate and conditionally stable finite difference scheme of explicit type with the help of a computer programming language Compaq Visual Fortran. The stability and convergence analysis has been carried out to establish the effect of velocity, temperature, concentration, skin friction, Nusselt number, Sherwood number, stream lines and isotherms line. Finally, the effects of various parameters are presented graphically and discussed qualitatively.

  16. Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

    Directory of Open Access Journals (Sweden)

    Abid Hussanan

    Full Text Available In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

  17. Parametric study on density stratification erosion caused by a horizontal steam jet interacting with a vertical plate obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Paranjape, S., E-mail: Sidharth.paranjape@psi.ch; Kapulla, R., E-mail: ralf.kapulla@psi.ch; Mignot, G., E-mail: guillaume.mignot@psi.ch; Paladino, D., E-mail: domenico.paladino@psi.ch

    2017-02-15

    Highlights: • Helium layer breakup by horizontal steam jet impinging on vertical plate. • A small change in geometric configuration lead to a large change in flow pattern. • The functional dependence of erosion front motion on time. • Creation of a concentration stratification in adjacent vessel. - Abstract: During postulated severe accident scenarios in nuclear power plants, a hydrogen-rich layer might form at the top of the reactor containment. Various flow patterns resulting from the release of steam from the primary circuit might break the layer and redistribute hydrogen in the containment. The prediction of the gas transport during the accident requires detailed modeling of the processes involved. Advanced lumped parameter codes or computational fluid dynamics codes are used for this purpose. These codes need to be validated against experimental data obtained in large scale experimental facilities, where scale distortions are reduced. In order to obtain the required data with high spatial and temporal resolution, experiments were carried out in the PANDA facility in Switzerland as a part of OECD/HYMERES (HYdrogen Mitigation Experiments for Reactor Safety) project. The present experiments address the breakup of a layer rich in helium (used as simulant for hydrogen), under steam environment and its redistribution in two interconnected vessels (total volume of 183.3 m{sup 3}) under the action of a diffused flow resulting from the interaction of a horizontal steam jet with a vertical plate obstruction. The influence of the distance between the jet exit and the obstruction on the flow pattern was investigated. Spatial and temporal distribution of the gas concentration, the temperature and local gas velocity field were measured. It was found that a small change in the geometric configuration lead to a large change in the flow pattern. Reducing the jet-obstruction distance slowed down the helium-layer erosion process by a factor of two. Additionally, the

  18. Exact solutions for unsteady free convection flow of carbon nanotubes over an oscillating vertical plate

    Science.gov (United States)

    Khalid, Asma; Jiann, Lim Yeou; Khan, Ilyas; Shafie, Sharidan

    2017-04-01

    The purpose of this paper is to study the unsteady convection flow of carbon nanotubes (CNTs) induced by free convection with oscillating plate condition. Single-wall CNTs are used with water as base fluids. The governing partial differential equations and boundary conditions are transformed into a set of ordinary differential equations using suitable dimensionless variables. These equations are solved analytically using Laplace transform technique to obtain the velocity and temperature profiles. Results for velocity and temperature are shown in various graphs and discussed for the embedded flow parameters in detail. It is observed that, velocity decreases with increasing CNTs volume fraction and an increase in CNTs volume fraction increases the nanofluid temperature, which leads to an increase in the heat transfer rates.

  19. Diffusion-thermo effect with hall current on unsteady hydromagnetic flow past an infinite vertical porous plate

    Directory of Open Access Journals (Sweden)

    J.R. Pattnaik

    2017-03-01

    Full Text Available An unsteady hydromagnetic flow past an infinite vertical porous plate has been analyzed to show the effect of an additional cross transport phenomenon, i.e. heat flux caused by concentration gradient in addition to the heat flux caused by temperature gradient. The effect of magnetic field on the fluid temperature and the heat transfer between fluid and wall is of considerable importance affecting the flow. Further, Hall current, an additional electric current density so generated perpendicular to both applied electric field and magnetic field has been taken into consideration in the present study. Moreover, the Dufour effect has been considered in energy equation leaving the equations of thermal diffusion and mass diffusion coupled. The coupled non-linear equations are solved by applying a special function Hhn(x. The effects of flow parameters are shown with the help of graphs and tables. A phenomenal observation, i.e. a radical change is marked near the plate in respect of Dufour number in the presence of suction. Further, it is to note that suction induces backflow in conjunction with opposing buoyancy forces. Hall current contributes to greater skin friction at the bounding surface.

  20. Radiation and chemical reaction effects on MHD Casson fluid flow past an oscillating vertical plate embedded in porous medium

    Directory of Open Access Journals (Sweden)

    Hari R. Kataria

    2016-03-01

    Full Text Available Analytic expression for unsteady free convective hydromagnetic boundary layer Casson fluid flow past an oscillating vertical plate embedded through porous medium in the presence of uniform transverse magnetic field, thermal radiation and chemical reaction is obtained. Both isothermal and ramped wall temperatures are taken into account. The governing equations are solved using Laplace transform technique and the solutions are presented in closed form. The numerical values of Casson fluid velocity, temperature and concentration at the plate are presented graphically for several values of the pertinent parameters. Effect of governing parameters on Skin friction, Nusselt number and Sherwood number is also discussed. Casson parameter γ is inversely proportional to the yield stress and it is observed that for the large value of Casson parameter, the fluid is close to the Newtonian fluid where the velocity is less than the Non-Newtonian fluid. It is seen that velocity increases and Temperature decreases with increase in thermal radiation R. Radiation parameter R signifies the relative contribution of conduction heat transfer to thermal radiation transfer. Concentration decreases tendency with chemical reaction parameter R′.

  1. A comparison of micro-structured flat-plate and cross-cut heat sinks for thermoelectric generation application

    DEFF Research Database (Denmark)

    Rezania, Alireza; Rosendahl, L. A.

    2015-01-01

    Heat sink configuration has strong impact on net power output from thermoelectric generators (TEGs). A weak cooling strategy can even cause negative net power output from the thermoelectric device. However, the net power output can be significantly improved by optimal design of the heat sink....... In this study, a micro-structured plate-fin heat sink is compared to a modified design of cross-cut heat sink applied to TEGs over a range of temperatures and thermal conductivities. The particular focus of this study is to explore the net power output from the TEG module. The three-dimensional governing......-fin heat sink is higher, while the TEG with cross-cut heat sink has higher maximum net power output at high flow inlet velocity. The maximum net power output is equal in the TEGs with plate-fin heat sink and cross-cut heat sink....

  2. Entropy generation in hydrodynamic slip flow over a vertical plate with convective boundary

    Energy Technology Data Exchange (ETDEWEB)

    Butt, Adnan Saeed; Munawar, Sufian; Ali, Asif [Quaid i Azam Univ., Islamabad (Pakistan); Meh Mood, Ahmer [International Islamic Univ., Islamabad (Pakistan)

    2012-09-15

    The present article aims to report the effects of hydrodynamic slip on entropy generation in the boundary layer flow over a vertical surface with convective boundary condition. Suitable similarity transformations are used to transform the fundamental equations of hydrodynamic and thermal boundary layer flow into ordinary differential equations. The governing equations are then solved numerically using the shooting method and the velocity and the temperature profiles are obtained for various values of parameters involved in the governing equations. The expressions for the entropy generation number and the Bejan number are presented and the results are discussed graphically and quantitatively for the slip parameter, the local Grashof number, the Prandtl number, the local convective heat transfer parameter, the group parameter and the local Reynolds number. It is observed that due to the presence of slip, entropy production in a thermal system can be controlled and reduced.

  3. Experimental study on the method of estimating the vertical design wave force acting on a submerged dual horizontal plate

    Directory of Open Access Journals (Sweden)

    Hyuck-Min Kweon

    2013-12-01

    Full Text Available A steel-type breakwater that uses a submerged dual horizontal porous plate was originally proposed by Kweon et al. (2005, and its hydrodynamic characteristics and design methodology were investigated in a series of subsequent researches. In particular, Kweon et al. (2011 proposed a method of estimating the vertical uplift force that acts on the horizontal plate, applicable to the design of the pile uplift drag force. However, the difference between the method proposed by Kweon et al. (2011, and the wave force measured at a different time without a phase difference, have not yet been clearly analyzed. In this study, such difference according to the method of estimating the wave force was analyzed, by measuring the wave pressure acting on a breakwater model. The hydraulic model test was conducted in a two-dimensional wave flume of 60.0 m length, 1.5 m height and 1.0 m width. The steepness range of the selected waves is 0.01~0.03, with regular and random signals. 20 pressure gauges were used for the measurement. The analysis results showed that the wave force estimate in the method of Kweon et al. (2011 was smaller than the wave force calculated from the maximum pressure at individual points, under a random wave action. Meanwhile, the method of Goda (1974 that was applied to the horizontal plate produced a smaller wave force, than the method of Kweon et al. (2011. The method of Kweon (2011 was already verified in the real sea test of Kweon et al. (2012, where the safety factor of the pile uplift force was found to be greater than 2.0. Based on these results, it was concluded that the method of estimating the wave force by Kweon et al. (2011 can be satisfactorily used for estimating the uplift force of a pile.

  4. Analysis and validation of a quasi-dynamic model for a solar collector field with flat plate collectors and parabolic trough collectors in series for district heating

    DEFF Research Database (Denmark)

    Tian, Zhiyong; Perers, Bengt; Furbo, Simon

    2018-01-01

    performance of the hybrid solar district heating plants is also presented. The measured and simulated results show that the integration of parabolic trough collectors in solar district heating plants can guarantee that the system produces hot water with relatively constant outlet temperature. The daily energy......A quasi-dynamic TRNSYS simulation model for a solar collector field with flat plate collectors and parabolic trough collectors in series was described and validated. A simplified method was implemented in TRNSYS in order to carry out long-term energy production analyses of the whole solar heating...... plant. The advantages of the model include faster computation with fewer resources, flexibility of different collector types in solar heating plant configuration and satisfactory accuracy in both dynamic and long-term analyses. In situ measurements were taken from a pilot solar heating plant with 5960 m...

  5. Effects of aligned magneticfield and radiation on the flow of ferrofluids over a flat plate with non-uniform heat source/sink

    Directory of Open Access Journals (Sweden)

    Sandeep N

    2015-03-01

    Full Text Available In this study we analyzed the influence of radiation and aligned magneticfield on the flow of ferrofluids over a flat plate in presence of non-uniform heat source/sink and slip velocity.  We considered Fe3O4 magnetic nano particles embedded within the two types of base fluids namely water and kerosene. The governing partial differential equations are transformed into nonlinear ordinary differential equations by using similarity transformation and solved numerically using bvp5c Matlab package. The effects of dimensionless quantities on the flow and temperature profiles along with the friction factor and Nusselt number is discussed and presented through graphs and tables. It is found that present results have an excellent agreement with the existed studies under some special assumptions. Results indicate that a raise in the aligned angle enhances the skin friction coefficient and heat transfer rate.

  6. Free convection boundary layer flow past a horizontal flat plate embedded in porous medium filled by nano-fluid containing gyro-tactic microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Aziz, A. [Department of Mechanical Engineering, School of Engineering and Applied Science, Gonzaga University, Spokane, WA 99258 (United States); Khan, W.A. [Department of Engineering Sciences, National University of Sciences and Technology, Karachi 75350 (Pakistan); Pop, I. [Department of Applied Mathematics, Babes-Bolyai University, Cluj-Napoca (Romania)

    2012-06-15

    The steady boundary layer free convection flow past a horizontal flat plate embedded in a porous medium filled by a water-based nano-fluid containing gyro-tactic microorganisms is investigated. The Oberbeck-Boussinesq approximation is assumed in the analysis. The effects of bio-convection parameters on the dimensionless velocity, temperature, nano-particle concentration and density of motile microorganisms as well as on the local Nusselt, Sherwood and motile microorganism numbers are investigated and presented graphically. In the absence of bio-convection, the results are compared with the existing data in the open literature and found to be in good agreement. The bio-convection parameters strongly influence the heat, mass, and motile microorganism transport rates. (authors)

  7. Effect of Some External Crosswise Stiffeners on the Heat Transfer and Pressure Distribution on a Flat Plate at Mach Numbers of 0.77, 1.39, and 1.98. Coord. No. AF-AM-69

    Science.gov (United States)

    Carter, Howard S.

    1957-01-01

    The heat transfer and pressures on the surfaces of several flat-plate models with various external crosswise stiffener arrangements are presented. The tests were made in a free jet at Mach numbers of 0.77, 1.39, and 1.98 for Reynolds numbers of 3 x 10(exp 6), 7 x 10(exp 6), and 14 x 10(exp 6), respectively, based on a length of 1 foot. The addition of external crosswise stiffeners to the flat-plate models caused large pressure and heat-transfer variations on the surfaces of the models.

  8. PLATE

    DEFF Research Database (Denmark)

    Kling, Joyce; Hjulmand, Lise-Lotte

    2008-01-01

    the Project in Language Assessment for Teaching in English (PLATE) language professionals from CBS’s Language Center observe teachers and provide feedback using evaluation criteria from the Common European Framework for Reference (CEFR) supplemented by some additional criteria which take the LSP nature......’s level of English is sufficient for the increasing number of courses offered in English each semester. This paper addresses these concerns and describes a pilot project initiated in 2003 at CBS to gauge the overall English language proficiency of those teaching content courses in English. Through...

  9. Effects of internal heat generation, thermal radiation and buoyancy force on a boundary layer over a vertical plate with a convective surface boundary condition

    OpenAIRE

    Tasawar Hayat; Awatif A. Hendi; Jacob A. Gbadeyan; Philip O. Olanrewaju

    2011-01-01

    In this paper we analyse the effects of internal heat generation, thermal radiation and buoyancy force on the laminar boundary layer about a vertical plate in a uniform stream of fluid under a convective surface boundary condition. In the analysis, we assumed that the left surface of the plate is in contact with a hot fluid whilst a stream of cold fluid flows steadily over the right surface; the heat source decays exponentially outwards from the surface of the plate. The similarity variable m...

  10. Pressure Loads Produced on a Flat-Plate Wing By Rocket Jets Exhausting in a Spanwise Direction Below the Wing and Perpendicular to a Free-Stream Flow of Mach Number 2.0

    Science.gov (United States)

    Falanga, Ralph A.; Janos, Joseph J.

    1961-01-01

    An investigation at a Reynolds number per foot of 14.4 x 10(exp 6) was made to determine the pressure loads produced on a flat-plate wing by rocket jets exhausting in a spanwise direction beneath the wing and perpendicular to a free-stream flow of Mach number 2.0. The ranges of the variables involved were (1) nozzle types - one sonic (jet Mach number of 1.00), two supersonic (jet Mach numbers of 1.74 and 3.04),. and one two-dimensional supersonic (jet Mach number of 1.71); (2) vertical nozzle positions beneath the wing of 4, 8 and 12 nozzle-throat diameters; and (3) ratios of rocket-chamber total pressure to free- stream static pressure from 0 to 130. The incremental normal force due to jet interference on the wing varied from one to two times the rocket thrust and generally decreased as the pressure ratio increased. The chordwise coordinate of the incremental-normal-force center of pressure remained upstream of the nozzle center line for the nozzle positions and pressure ratios of the investigation. The chordwise coordinate approached zero as the jet vertical distance beneath the wing increased. In the spanwise direction there was little change due to varying rocket-jet position and pressure ratio. Some boundary-layer flow separation on the wing was observed for the rocket jets close to the wing and at the higher pressure ratios. The magnitude of the chordwise and spanwise pressure distributions due to jet interference was greatest for rocket jets close to the wing and decreased as the jet was displaced farther from the wing. The design procedure for the rockets used is given in the appendix.

  11. A study of elastic and plastic stress concentration factors due to notches and fillets in flat plates

    Science.gov (United States)

    Hardrath, Herbert F; Ohman, Lachlan

    1953-01-01

    Six large 24s-t3 aluminum-alloy-sheet specimens containing various notches or fillets were tested in tension to determine their stress concentration factors in both the elastic and plastic ranges. The elastic stress concentration factors were found to be slightly higher than those calculated by Neuber's method and those obtained photoelastically by Frocht. The results showed further that the stress concentration factor decreases as strains at the discontinuity enter the plastic range. A generalization of Stowell's relation for the plastic stress concentration factor at a circular hole in an infinite plate was applied to the specimen shapes tested and gave good agreement with test results.

  12. Standard practice for acoustic emission examination of plate-like and flat panel composite structures used in aerospace applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers acoustic emission (AE) examination or monitoring of panel and plate-like composite structures made entirely of fiber/polymer composites. 1.2 The AE examination detects emission sources and locates the region(s) within the composite structure where the emission originated. When properly developed AE-based criteria for the composite item are in place, the AE data can be used for nondestructive examination (NDE), characterization of proof testing, documentation of quality control or for decisions relative to structural-test termination prior to completion of a planned test. Other NDE methods may be used to provide additional information about located damage regions. For additional information see Appendix X1. 1.3 This practice can be applied to aerospace composite panels and plate-like elements as a part of incoming inspection, during manufacturing, after assembly, continuously (during structural health monitoring) and at periodic intervals during the life of a structure. 1.4 This pra...

  13. Magnetic field effects on unsteady convective flow along a vertical porous flat surface embedded in a porous medium with constant suction and heat sink

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.S.; Das, P. [Department of Pysics, K B D A B College, Nirakarpur, Khurda-752 019 (Orissa) (India); Mohanty, J. [Department of Physics, ABIT, CDA, Sector-I, Bidanasi, Cuttack-753 014, (Orissa) (India)

    2011-07-01

    The magnetohydrodynamic unsteady convective flow of a viscous incompressible fluid along a vertical porous plate embedded in a porous medium with constant suction and heat sink is considered. Approximate solutions for velocity, temperature, skin friction and rate of heat transfer are obtained by solving the governing equations of the flow field using multi parameter perturbation technique. The effects of various flow parameters affecting the flow field are discussed with the help of figures and table. It is observed that a growing magnetic parameter or heat sink parameter retards the transient velocity of the flow field while the Grashof number or permeability parameter reverses the effect. Further, an increase in magnetic parameter or Prandtl number or heat sink parameter decreases the transient temperature of the flow field. A growing permeability parameter enhances the magnitude of skin friction and the rate of heat transfer at the wall, while the magnetic parameter reverses the effect.

  14. A Comparative Analysis of Seismological and Gravimetric Crustal Thicknesses below the Andean Region with Flat Subduction of the Nazca Plate

    Directory of Open Access Journals (Sweden)

    Mario E. Gimenez

    2009-01-01

    Full Text Available A gravimetric study was carried out in a region of the Central Andean Range between 28∘ and 32∘ south latitudes and from 72∘ and 66∘ west longitudes. The seismological and gravimetrical Moho models were compared in a sector which coincides with the seismological stations of the CHARGE project. The comparison reveals discrepancies between the gravity Moho depths and those obtained from seismological investigations (CHARGE project, the latter giving deeper values than those resulting from the gravimetric inversion. These discrepancies are attenuated when the positive gravimetric effect of the Nazca plate is considered. Nonetheless, a small residuum of about 5 km remains beneath the Cuyania terrane region, to the east of the main Andean chain. This residuum could be gravimetrically justified if the existence of a high density or eclogitized portion of the lower crust is considered. This result differed from the interpretations from Project “CHARGE” which revealed that the entire inferior crust extending from the Precordillera to the occidental “Sierras Pampeanas” could be “eclogitized”. In this same sector, we calculated the effective elastic thickness (Te of the crust. These results indicated an anomalous value of Te = 30 km below the Cuyania terrane. This is further conclusive evidence of the fact that the Cuyania terrane is allochthonous, for which also geological evidences exist.

  15. Effect of Magnetic Field on Entropy Generation Due to Laminar Forced Convection Past a Horizontal Flat Plate

    Directory of Open Access Journals (Sweden)

    Moh'd A. Al-Nimr

    2004-06-01

    Full Text Available Magnetic field effect on local entropy generation due to steady two-dimensional laminar forced convection flow past a horizontal plate was numerically investigated. This study was focused on the entropy generation characteristics and its dependency on various dimensionless parameters. The effect of various dimensionless parameters, such as Hartmann number (Ha, Eckert number (Ec, Prandtl number (Pr, Joule heating parameter (R and the free stream temperature parameter (θ∞ on the entropy generation characteristics is analyzed. The dimensionless governing equations in Cartesian coordinate were solved by an implicit finite difference technique. The solutions were carried out for Ha2=0.5-3, Ec=0.01-0.05, Pr=1-5 and θ∞=1.1-2.5. It was found that, the entropy generation increased with increasing Ha, Ec and R. While, increasing the free stream temperature parameter, and Prandtl number tend to decrease the local entropy generation.

  16. Soret and heat generation effects on MHD Casson fluid flow past an oscillating vertical plate embedded through porous medium

    Directory of Open Access Journals (Sweden)

    Hari R. Kataria

    2016-09-01

    Full Text Available Analytical solution of thermal diffusion and heat generation effects on MHD Casson fluid flow past an oscillating vertical plate embedded through porous medium in the presence of thermal radiation and chemical reaction is obtained. Ramped wall temperature with ramped surface concentration, isothermal temperature with ramped surface concentration and isothermal temperature with constant surface concentration are taken into account. The governing non-dimensional equations are solved using Laplace transform technique and the solutions are presented in closed form. In order to get a perfect understanding of the physics of the problem we obtained numerical results using Matlab software and clarified with the help of graphical illustrations. With the help of velocity, temperature and concentration, Skin friction, Nusselt number and Sherwood number are obtained and represent through tabular form. Casson parameter is inversely proportional to the yield stress and it is observed that for the large value of Casson parameter, the fluid is close to the Newtonian fluid where the velocity is less than the non-Newtonian fluid. The intensification in values of Soret number produces a raise in the mass buoyancy force which results an increase in the value of velocity.

  17. Similarity Solution for Combined Free-Forced Convection Past a Vertical Porous Plate in a Porous Medium with a Convective Surface Boundary Condition

    Directory of Open Access Journals (Sweden)

    Garg P.

    2016-12-01

    Full Text Available This paper studies the mathematical implications of the two dimensional viscous steady laminar combined free-forced convective flow of an incompressible fluid over a semi infinite fixed vertical porous plate embedded in a porous medium. It is assumed that the left surface of the plate is heated by convection from a hot fluid which is at a temperature higher than the temperature of the fluid on the right surface of the vertical plate. To achieve numerical consistency for the problem under consideration, the governing non linear partial differential equations are first transformed into a system of ordinary differential equations using a similarity variable and then solved numerically under conditions admitting similarity solutions. The effects of the physical parameters of both the incompressible fluid and the vertical plate on the dimensionless velocity and temperature profiles are studied and analysed and the results are depicted both graphically and in a tabular form. Finally, algebraic expressions and the numerical values are obtained for the local skin-friction coefficient and the local Nusselt number.

  18. Magnetohydrodynamic free convection heat and mass transfer of a heat generating fluid past an impulsively started infinite vertical porous plate with Hall current and radiation absorption

    Energy Technology Data Exchange (ETDEWEB)

    Kinyanjui, M.; Kwanza, J.K.; Uppal, S.M. [Jomo Kenyatta University of Agriculture and Technology, Nairobi (Cayman Islands). Dept. of Mathematics and Statistics

    2001-05-01

    Simultaneous heat and mass transfer in unsteady free convection flow with radiation absorption past an impulsively started infinite vertical porous plate subjected to a strong magnetic field is presented. The governing equations for the problem are solved by a finite difference scheme. The influence of the various parameters on the convectively cooled or convectively heated plate in the laminar boundary layer are considered. An analysis of the effects of the parameters on the concentration, velocity and temperature profiles, as well as skin friction and the rates of mass and heat transfer, is done with the aid of graphs and tables. (author)

  19. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: The mechanism of the drilling of holes in vertical metallic plates by cw CO2 laser radiation

    Science.gov (United States)

    Likhanskii, V. V.; Loboiko, A. I.; Antonova, G. F.; Krasyukov, A. G.; Sayapin, V. P.

    1999-02-01

    The possibility of making a hole in a vertical plate with the aid of laser radiation at a surface temperature not exceeding the boiling point is analysed neglecting the vapour pressure. The mechanism of the degradation of the liquid layer involving a reduction of its thickness, as a result of the redistribution of the molten mass owing to the operation of the force of gravity and of thermocapillary convection, is examined. The theoretical dependence of the critical size of the molten zone on the plate thickness is obtained and a comparison is made with experimental data.

  20. Co-production of lipids, eicosapentaenoic acid, fucoxanthin, and chrysolaminarin by Phaeodactylum tricornutum cultured in a flat-plate photobioreactor under varying nitrogen conditions

    Science.gov (United States)

    Gao, Baoyan; Chen, Ailing; Zhang, Wenyuan; Li, Aifen; Zhang, Chengwu

    2017-10-01

    The marine diatom Phaeodactylum tricornutum is a polymorphological, ecologically significant, and well-studied model of unicellular microalga. This diatom can accumulate diverse important metabolites. Herein, we cultured P. tricornutum in an internally installed tie-piece flat-plate photobioreactor under 14.5 m mol L-1 (high nitrogen, HN) and 2.9 m mol L-1 (low nitrogen, LN) of KNO3 and assessed its time-resolved changes in biochemical compositions. The results showed that HN was inductive to accumulate high biomass (4.1 g L-1). However, the LN condition could accelerate lipid accumulation in P. tricornutum. The maximum total lipid (TL) content under LN was up to 42.5% of biomass on day 12. Finally, neutral lipids (NLs) were 63.8% and 75.7% of TLs under HN and LN, respectively. The content of EPA ranged from 2.3% to 1.5% of dry weight during the growth period under the two culture conditions. Peak volumetric lipid productivity of 128.4 mg L-1d-1 was achieved in the HN group (on day 9). The highest volumetric productivity values of EPA, chrysolaminarin, and fucoxanthin were obtained in the exponential phase (on day 6) under HN, which were 9.6, 93.6, and 4.7 mg L-1d-1, respectively. In conclusion, extractable amounts of lipids, EPA, fucoxanthin, and chrysolaminarin could be obtained from P. tricornutum by regulating the culture conditions.

  1. Evolution of disturbances in the shock layer on a flat plate in the flow of a mixture of vibrationally excited gases

    Science.gov (United States)

    Kirilovskiy, S. V.; Poplavskaya, T. V.; Tsyryulnikov, I. S.; Maslov, A. A.

    2017-05-01

    The results of the numerical and experimental investigations of the evolution of the disturbances in a hypersonic shock layer on a flat plate streamlined by a flow of the mixture of vibrationally excited gases are presented. The experimental study was conducted in the hot-shot high-enthalpy wind tunnel IT-302 of the ITAM SB RAS. The numerical simulation was carried out with the aid of the ANSYS Fluent package using the solution of the unsteady two-dimensional Navier-Stokes equations with the incorporation of the user-created modules and enabling the consideration of the vibrational non-equilibrium of the carbon dioxide molecules within the framework of the model of the two-temperature aerodynamics. It was obtained that an increase in the carbon dioxide concentration in the mixture with air leads to a reduction of the intensity of pressure disturbances on the surface. The efficiency (up to 20 %) of the method of sound absorbing coatings in the vibrationally excited flows of the mixture of the carbon dioxide and air has been shown.

  2. Simultaneous enhancement of Chlorella vulgaris growth and lipid accumulation through the synergy effect between light and nitrate in a planar waveguide flat-plate photobioreactor.

    Science.gov (United States)

    Liao, Qiang; Sun, Yahui; Huang, Yun; Xia, Ao; Fu, Qian; Zhu, Xun

    2017-11-01

    Interval between adjacent planar waveguides and light intensity emitted from waveguide surface were the primary two factors affecting light distribution characteristics in the planar waveguide flat-plate photobioreactor (PW-PBR). In this paper, the synergy effect between light and nitrate in the PW-PBR was realized to simultaneously enhance microalgae growth and lipid accumulation. Under an interval of 10mm between adjacent planar waveguides, 100% of microalgae cells in regions between adjacent waveguides could be illuminated. Chlorella vulgaris growth and lipid accumulation were synchronously elevated as light intensities emitted from planar waveguide surface increasing. With an identical initial nitrate concentration of 18mM, the maximum lipid content (41.66% in dry biomass) and lipid yield (2200.25mgL-1) were attained under 560μmolm-2s-1, which were 86.82% and 133.56% higher relative to those obtained under 160μmolm-2s-1, respectively. The PW-PBR provides a promising way for microalgae lipid production. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. A Systematic Study of Separators in Air-Breathing Flat-Plate Microbial Fuel Cells—Part 1: Structure, Properties, and Performance Correlations

    Directory of Open Access Journals (Sweden)

    Sona Kazemi

    2016-01-01

    Full Text Available Passive air-breathing microbial fuel cells (MFCs are a promising technology for energy recovery from wastewater and their performance is highly dependent on characteristics of the separator that isolates the anaerobic anode from the air-breathing cathode. The goal of the present work is to systematically study the separator characteristics and its effect on the performance of passive air-breathing flat-plate MFCs (FPMFCs. This was performed through characterization of structure, properties, and performance correlations of eight separators in Part 1 of this work. Eight commercial separators were characterized, in non-inoculated and inoculated setups, and were examined in passive air-breathing FPMFCs with different electrode spacing. The results showed a decrease in the peak power density as the oxygen and ethanol mass transfer coefficients in the separators increased, due to the increase of mixed potentials especially at smaller electrode spacing. Increasing the electrode spacing was therefore desirable for the application of diaphragms. The highest peak power density was measured using Nafion®117 with minimal electrode spacing, whereas using Nafion®117 or Celgard® with larger electrode spacing resulted in similar peak powers. Part 2 of this work focuses on numerical modelling of the FPMFCs based on mixed potential theory, implementing the experimental data from Part 1.

  4. Endwall heat transfer in the junction region of a circular cylinder normal to a flat plate at 30 and 60 degrees from stagnation point of the cylinder

    Science.gov (United States)

    Nagamatsu, H. T.; Choi, K. Y.

    1987-01-01

    The objective of this experimental study was to investigate the influence of horseshoe vortex on the heat transfer on a flat plate near the base of a protruding cylinder. The partial shock reflection technique was used to produce the flow Mach number of 0.14 which simulated the mean inlet flow Mach number for the first stage vanes of the turbine after combustor. Fast response thin-film platinum heat gages were used to measure the heat transfer flux for radial distances of 0.75, 0.875, 1.0, 1.125 cylinder diameter. For a low Reynolds number of 20,000, r/D = 0.75, and angular location from the stagnation point = 60 deg, the maximum increase in the heat transfer rate with the cylinder was observed to be approximately 460 percent greater than without the cylinder. On the other hand, the increase in the heat flux for a high Reynolds number of 300,000 was approximately 70 percent greater. For the heat gages located along 30 deg and 60 deg angular locations from the stagnation point, the strong effect of the horseshoe vortex was observed in the junction region. The increase in the heat transfer rate depended on the type of boundary layer and on the boundary layer thickness ahead of the cylinder.

  5. The economic payoff for a state-of-the-art high-efficiency flat-plate crystalline silicon solar cell technology

    Science.gov (United States)

    Bickler, Donald B.; Callaghan, W. T.

    1987-01-01

    In 1986 during the flat-plate solar array project, silicon solar cells 4.0 sq cm in area were fabricated at the Jet Propulsion Laboratory (JPL) with a conversion efficiency of 20.1 percent (AM1.5-global). Sixteen cells were processed with efficiencies measuring 19.5 percent (AM1.5 global) or better. These cells were produced using refined versions of conventional processing methods, aside from certain advanced techniques that bring about a significant reduction in a major mechanism (surface recombination) that limits cell efficiency. Wacker Siltronic p-type float-zone 0.18-ohm-cm wafers were used. Conversion efficiencies in this range have previously been reported by other researchers, but generally on much smaller (0.5 vs. 4.0 cm) devices which have undergone sophisticated and costly processing steps. An economic analysis is presented of the potential payoffs for this approach, using the Solar Array Manufacturing Industry Costing Standards (SAMICS) methodology. The process sequence used and the assumptions made for capturing the economies of scale are presented.

  6. Modeling of quantitative effects of water components on the photocatalytic degradation of 17α-ethynylestradiol in a modified flat plate serpentine reactor.

    Science.gov (United States)

    Wang, Dawei; Li, Yi; Li, Guoping; Wang, Chao; Zhang, Wenlong; Wang, Qing

    2013-06-15

    The effect of water components on the photocatalytic degradation of organic pollutants was incompletely understood, especially in the case of hydroxyl radical (•OH) generation and scavenging. Previous studies have used various methods to determine the rate constants for the reactions between •OH and water components, but the interactions between water components were not taken into concern. In this study, a sequential relative rate technique was used to investigate the effects of water components on the rates of •OH generation and EE2 degradation in a modified flat plate serpentine reactor, including NO₃(-), H₂PO₄(-), SO₄(2-), CO₃(2-), Cl(-), Na(+), Fe(3+), dissolved organic matter (DOM) etc. The results reflected that NO₃(-) and DOM accelerated the photodegradation of 17α-ethynylestradiol (EE2) (3.2% and 21.2%, respectively). Cl(-) and Fe(3+) inhibited that process (5.2% and 3.1%, respectively). Finally, a model for the photocatalytic degradation of EE2 was developed for the first time, taking the obtained rate constants, catalyst concentrations, flow velocities and light intensities into concern. A good agreement was observed between the model and experimental profiles. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Influence of surface geometry on the culture of human cell lines: A comparative study using flat, round-bottom and v-shaped 96 well plates.

    Directory of Open Access Journals (Sweden)

    Sara Shafaie

    Full Text Available In vitro cell based models have been invaluable tools for studying cell behaviour and for investigating drug disposition, toxicity and potential adverse effects of administered drugs. Within this drug discovery pipeline, the ability to assess and prioritise candidate compounds as soon as possible offers a distinct advantage. However, the ability to apply this approach to a cell culture study is limited by the need to provide an accurate, in vitro-like, microenvironment in conjunction with a low cost and high-throughput screening (HTS methodology. Although the geometry and/or alignment of cells has been reported to have a profound influence on cell growth and differentiation, only a handful of studies have directly compared the growth of a single cell line on different shaped multiwell plates the most commonly used substrate for HTS, in vitro, studies. Herein, the impact of various surface geometries (flat, round and v-shaped 96 well plates, as well as fixed volume growth media and fixed growth surface area have been investigated on the characteristics of three commonly used human cell lines in biopharmaceutical research and development, namely ARPE-19 (retinal epithelial, A549 (alveolar epithelial and Malme-3M (dermal fibroblastic cells. The effect of the surface curvature on cells was characterised using a combination of a metabolic activity assay (CellTiter AQ/MTS, LDH release profiles (CytoTox ONE and absolute cell counts (Guava ViaCount, respectively. In addition, cell differentiation and expression of specific marker proteins were determined using flow cytometry. These in vitro results confirmed that surface topography had a significant effect (p < 0.05 on cell activity and morphology. However, although specific marker proteins were expressed on day 1 and 5 of the experiment, no significant differences were seen between the different plate geometries (p < 0.05 at the later time point. Accordingly, these results highlight the impact of

  8. Chemical reaction and radiation effects on mixed convection heat and mass transfer over a vertical plate in power-law fluid saturated porous medium

    Directory of Open Access Journals (Sweden)

    D. Srinivasacharya

    2016-01-01

    Full Text Available Mixed convection heat and mass transfer along a vertical plate embedded in a power-law fluid saturated Darcy porous medium with chemical reaction and radiation effects is studied. The governing partial differential equations are transformed into ordinary differential equations using similarity transformations and then solved numerically using shooting method. A parametric study of the physical parameters involved in the problem is conducted and a representative set of numerical results is illustrated graphically.

  9. HEAT AND MASS TRANSFER EFFECTS ON FLOW PAST PARABOLIC STARTING MOTION OF ISOTHERMAL VERTICAL PLATE IN THE PRESENCE OF FIRST ORDER CHEMICAL REACTION

    Directory of Open Access Journals (Sweden)

    R. Muthucumaraswamy

    2013-06-01

    Full Text Available An exact solution of unsteady flow past a parabolic starting motion of the infinite isothermal vertical plate with uniform mass diffusion, in the presence of a homogeneous chemical reaction of the first order, has been studied. The plate temperature and the concentration level near the plate are raised uniformly. The dimensionless governing equations are solved using the Laplace transform technique. The effect of velocity profiles are studied for different physical parameters, such as chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number, and time. It is observed that velocity increases with increasing values of thermal Grashof number or mass Grashof number. The trend is reversed with respect to the chemical reaction parameter.

  10. Study of vortex dislocation in the wake of a flat plate with finite thickness; Yugen atsusa heiban koryu ni okeru uzu ten'i kozo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Abe, S.; Maekawa, H. [University of Electronic-Communication, Tokyo (Japan)

    2000-09-25

    Wake structures of a flat plate with finite thickness are studied using the rake of X-wires techniques. Parallel and oblique shedding modes in the wake flow are investigated. These modes depend on the flat plate end conditions. In the present paper, we demonstrate that manipulation of the end conditions yields a vortex dislocation that appears periodically at the same location. Vortex linkup dynamics phenomena in the dislocations are observed with smoke-wire flow visualization. Flow patterns of dislocation are analyzed by mean of the pseudo-flow visualization of the rake data. The linkup structure due to a misfit of two oblique shedding vortices appears periodically in the flow patterns. Evolutions of the power spectra of velocity fluctuations explain the generation of large-scale turbulent structure downstream due to the growth of a low-frequency mode and the cascade process of low/high frequency components. (author)

  11. The sizes of Flat Plate and Evacuated Tube Collectors with Heat Pipe area as a function of the share of solar system in the heat demand

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    Olek Małgorzata

    2016-01-01

    Full Text Available The popularity of solar collectors in Poland is still increasing. The correct location of the collectors and a relatively high density of solar radiation allow delivering heat even in spite of relatively low ambient temperature. Moreover, solar systems used for heating domestic heat water (DHW in summer allow nearly complete elimination of conventional energy sources (e.g. gas, coal. That is why more and more house owners in Poland decide to install solar system installations. In Poland the most common types of solar collectors are flat plate collectors (FPC and evacuated tube collectors with heat pipe (ETCHP; both were selected for the analysis. The heat demand related to the preparation of hot water, connected with the size of solar collectors’ area, has been determined. The analysis includes FPC and ETCHP and heat demand of less than 10 000 kWh/year. Simulations were performed with the Matlab software and using data from a typical meteorological year (TMY. In addition, a 126–year period of measurements of insolation for Krakow has been taken into account. The HDKR model (Hay, Davis, Klucher, Reindl was used for the calculation of solar radiation on the absorber surface. The monthly medium temperature of the absorber depends on the amount of solar system heat and on the heat demand. All the previously mentioned data were used to determine solar efficiency. Due to the fact that solar efficiency and solar system heat are connected, the calculations were made with the use of an iterative method. Additionally, the upper limit for monthly useful solar system heat is resulted from the heat demand and thus the authors prepared a model of statistical solar system heat deviations based on the Monte Carlo method. It has been found that an increase in the useful solar system heat in reference to the heat demand is associated with more than proportional increase in the sizes of the analyzed surfaces of solar collector types.

  12. Comparing between predicted output temperature of flat-plate solar collector and experimental results: computational fluid dynamics and artificial neural network

    Directory of Open Access Journals (Sweden)

    F Nadi

    2017-05-01

    back propagation learning rule was used to simulate the output temperature of a solar collector. The number of neurons within the hidden layer varied from 1 to 20. The hyperbolic tan- sigmoid and pure-line were used as the transfer function in the hidden layer and output layer, respectively. Minimization of error was achieved using the Levenberg-Marquardt algorithm. To carry out the aforementioned steps, the dataset (105 observations was split into training (70 observations, and test (35 observations data. Training sets used to develop models included air velocity, solar radiation, time of the day, ambient moisture and temperature values as inputs with an associated temperature of the collector as outputs. The aim of every training algorithm is to reduce this global error by adjusting the weights and biases. Results and Discussion Compare experimental results with ANN The performance of the three-layer ANN for the prediction of output temperature of flat-plate solar collector by the Levenberg–Marquardt training algorithm was illustrated in Fig. 4. ANN predicted output temperatures with R2 and RMSE of 0.92 and 1.23, respectively. Furthermore, the maximum error in prediction of output temperature of solar collector was 3.3 K. These results are in agreement with Tripathy and Kumar, (2009 those who have predicted the output temperatures of food product in the solar drier using ANN with and RMSE of 0.95 and 0.77, respectively. Compare experimental results with CFD simulation Fig. 6 shows that over the starting length of the absorber plate, there is a variation of the velocity profile which is caused by sharp geometry and it leads to some recirculation of the air in this part of absorber plate. After this part of boundary layers, flow is fully developed and velocity profile becomes smoother and constant. Fig. 8 shows that the predicted temperature was within the experimentally measured temperature. The highest differences between simulated and experimental temperatures

  13. Nonlinear radiation heat transfer effects in the natural convective boundary layer flow of nanofluid past a vertical plate: a numerical study.

    Directory of Open Access Journals (Sweden)

    Meraj Mustafa

    Full Text Available The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge-Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter.

  14. Mixed Convective Flow of an Elastico-Viscous Fluid Past a Vertical Plate in the Presence of Thermal Radiation and Chemical Reaction with an Induced Magnetic Field

    Science.gov (United States)

    Das, Utpal Jyoti

    2016-01-01

    The purpose of the study is to investigate the steady, two-dimensional, hydromagnetic, mixed convection heat and mass transfer of a conducting, optically thin, incompressible, elastico-viscous fluid (characterized by the Walters' B' model) past a permeable, stationary, vertical, infinite plate in the presence of thermal radiation and chemical reaction with account for an induced magnetic field. The governing equations of the flow are solved by the series method, and expressions for the velocity field, induced magnetic field, temperature field, and the skin friction are obtained.

  15. A Note on Variable Viscosity and Chemical Reaction Effects on Mixed Convection Heat and Mass Transfer Along a Semi-Infinite Vertical Plate

    Directory of Open Access Journals (Sweden)

    Mostafa A. A. Mahmoud

    2007-01-01

    Full Text Available In the present study, an analysis is carried out to study the variable viscosity and chemical reaction effects on the flow, heat, and mass transfer characteristics in a viscous fluid over a semi-infinite vertical porous plate. The governing boundary layer equations are written into a dimensionless form by similarity transformations. The transformed coupled nonlinear ordinary differential equations are solved numerically by using the shooting method. The effects of different parameters on the dimensionless velocity, temperature, and concentration profiles are shown graphically. In addition, tabulated results for the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are presented and discussed.

  16. Chemical reaction effect on an unsteady MHD free convection flow past a vertical porous plate in the presence of suction or injection

    Directory of Open Access Journals (Sweden)

    Shivaiah S.

    2012-01-01

    Full Text Available The objective of this paper is to analyze the effect of chemical reaction on unsteady magneto hydrodynamic free convective fluid flow past a vertical porous plate in the presence of suction or injection. The governing equations of the flow field are solved numerically by a finite element method. The effects of the various parameters on the velocity, temperature and concentration profiles are presented graphically and values of skin-friction coefficient, Nusselt number and Sherwood number for various values of physical parameters are presented through tables.

  17. Thermal conductivity of a graphite bipolar plate (BPP) and its thermal contact resistance with fuel cell gas diffusion layers: Effect of compression, PTFE, micro porous layer (MPL), BPP out-of-flatness and cyclic load

    Science.gov (United States)

    Sadeghifar, Hamidreza; Djilali, Ned; Bahrami, Majid

    2015-01-01

    This paper reports on measurements of thermal conductivity of a graphite bipolar plate (BPP) as a function of temperature and its thermal contact resistance (TCR) with treated and untreated gas diffusion layers (GDLs). The thermal conductivity of the BPP decreases with temperature and its thermal contact resistance with GDLs, which has been overlooked in the literature, is found to be dominant over a relatively wide range of compression. The effects of PTFE loading, micro porous layer (MPL), compression, and BPP out-of-flatness are also investigated experimentally. It is found that high PTFE loadings, MPL and even small BPP out-of-flatness increase the BPP-GDL thermal contact resistance dramatically. The paper also presents the effect of cyclic load on the total resistance of a GDL-BPP assembly, which sheds light on the behavior of these materials under operating conditions in polymer electrolyte membrane fuel cells.

  18. Effects of internal heat generation, thermal radiation and buoyancy force on a boundary layer over a vertical plate with a convective surface boundary condition

    Directory of Open Access Journals (Sweden)

    Tasawar Hayat

    2011-09-01

    Full Text Available In this paper we analyse the effects of internal heat generation, thermal radiation and buoyancy force on the laminar boundary layer about a vertical plate in a uniform stream of fluid under a convective surface boundary condition. In the analysis, we assumed that the left surface of the plate is in contact with a hot fluid whilst a stream of cold fluid flows steadily over the right surface; the heat source decays exponentially outwards from the surface of the plate. The similarity variable method was applied to the steady state governing non-linear partial differential equations, which were transformed into a set of coupled non-linear ordinary differential equations and were solved numerically by applying a shooting iteration technique together with a sixth-order Runge–Kutta integration scheme for better accuracy. The effects of the Prandtl number, the local Biot number, the internal heat generation parameter, thermal radiation and the local Grashof number on the velocity and temperature profiles are illustrated and interpreted in physical terms. A comparison with previously published results on similar special cases showed excellent agreement.

  19. Thermo-fluid-dynamics of natural convection around a heated vertical plate with a critical assessment of the standard similarity theory

    Science.gov (United States)

    Guha, Abhijit; Nayek, Subhajit

    2017-10-01

    A compulsory element of all textbooks on natural convection has been a detailed similarity analysis for laminar natural convection on a heated semi-infinite vertical plate and a routinely used boundary condition for such analysis is u = 0 at x = 0. The same boundary condition continues to be assumed in related theoretical analyses, even in recent publications. The present work examines the consequence of this long-held assumption, which appears to have never been questioned in the literature, on the fluid dynamics and heat transfer characteristics. The assessment has been made here by solving the Navier-Stokes equations numerically with two boundary conditions—one with constrained velocity at x = 0 to mimic the similarity analysis and the other with no such constraints simulating the case of a heated vertical plate in an infinite expanse of the quiescent fluid medium. It is found that the fluid flow field given by the similarity theory is drastically different from that given by the computational fluid dynamics (CFD) simulations with unconstrained velocity. This also reflects on the Nusselt number, the prediction of the CFD simulations with unconstrained velocity being quite close to the experimentally measured values at all Grashof and Prandtl numbers (this is the first time theoretically computed values of the average Nusselt number N u ¯ are found to be so close to the experimental values). The difference of the Nusselt number (Δ N u ¯ ) predicted by the similarity theory and that by the CFD simulations (as well as the measured values), both computed with a high degree of precision, can be very significant, particularly at low Grashof numbers and at Prandtl numbers far removed from unity. Computations show that within the range of investigations (104 ≤ GrL ≤ 108, 0.01 ≤ Pr ≤ 100), the maximum value of Δ N u ¯ may be of the order 50%. Thus, for quantitative predictions, the available theory (i.e., similarity analysis) can be rather inadequate. With

  20. Heat and mass transfer on unsteady MHD free convection rotating flow through a porous medium over an infinite vertical plate with hall effects

    Science.gov (United States)

    Babu, D. Dastagiri; Venkateswarlu, S.; Reddy, E. Keshava

    2017-07-01

    In this paper, we have considered the unsteady MHD free convection flow of an incompressible electrically conducting fluid through porous medium bounded by an infinite vertical porous surface in the presence of heat source and chemical reaction in a rotating system taking hall current into account. The flow through porous medium is governed by Brinkman's model for the momentum equation. In the undisturbed state, both the plate and fluid in porous medium are in solid body rotation with the same angular velocity about normal to the infinite vertical plane surface. The vertical surface is subjected to the uniform constant suction perpendicular to it and the temperature on the surface varies with time about a non-zero constant mean while the temperature of free stream is taken to be constant. The exact solutions for the velocity, temperature and concentration are obtained making use of perturbation technique. The velocity expression consists steady state and oscillatory state. It reveals that, the steady part of the velocity field has three layer characters while the oscillatory part of the fluid field exhibits a multi-layer character. The influence of various flow parameters on the velocity, temperature and concentration is analysed graphically, and computational results for the skin friction, Nusselt number and Sherwood number are also obtained in the tabular forms.

  1. Double diffusive unsteady convective micropolar flow past a vertical porous plate moving through binary mixture using modified Boussinesq approximation

    Directory of Open Access Journals (Sweden)

    Isaac Lare Animasaun

    2016-06-01

    Full Text Available The problem of unsteady convective with thermophoresis, chemical reaction and radiative heat transfer in a micropolar fluid flow past a vertical porous surface moving through binary mixture considering temperature dependent dynamic viscosity and constant vortex viscosity has been investigated theoretically. For proper and correct analysis of fluid flow along vertical surface with a temperature lesser than that of the free stream, Boussinesq approximation and temperature dependent viscosity model were modified and incorporated into the governing equations. The governing equations are converted to systems of ordinary differential equations by applying suitable similarity transformations and solved numerically using fourth-order Runge–Kutta method along with shooting technique. The results of the numerical solution are presented graphically and in tabular forms for different values of parameters. Velocity profile increases with temperature dependent variable fluid viscosity parameter. Increase of suction parameter corresponds to an increase in both temperature and concentration within the thin boundary layer.

  2. Loads Induced on a Flat-Plate Wing by an Air Jet Exhausting Perpendicularly through the Wing and Normal to a Free-Stream Flow of Mach Number 2.0

    Science.gov (United States)

    Janos, Joseph J.

    1961-01-01

    Measurements were made of loads induced on a flat-plate wing by an air jet exhausting perpendicularly through the wing and normal to the free-stream flow.The investigation was conducted at a free-stream Mach number of 2.0 and a Reynolds number per foot of 14.4 x 10(exp 6). An axially symmetric sonic nozzle and two supersonic nozzles were employed for the jets. The supersonic nozzles consisted of an axially symmetric nozzle with exit Mach number of 3.44 and a two-dimensional nozzle with exit Mach number of 1.76. The ratio of nozzle total pressure to free-stream static pressure was varied from 20 to 110. Negative loads were induced on the flat-plate wing by all the jets. As the nozzle pressure ratio was increased the magnitude of interference loads due to jet thrust decreased. The chordwise center-of-pressure location generally moved toward the nozzle center line as the pressure ratio was increased.

  3. Experimental study of surface pressures induced on a flat plate and a body of revolution by various dual jet configurations. [wind tunnel tudies of a jet in a cross flow for V/STOL applications

    Science.gov (United States)

    Schetz, J. A.; Jakubowski, A. K.

    1982-01-01

    The effect of the angle of a jet to a crossflow, the performance of dual jet configurations, and a jet injected from a body of revolution as opposed to a flat plate were investigated during experiments conducted in the 7x10 tunnel at NASA Ames at Velocities from 14.5 m/sec to 35.8 m/sec (47.6 to 117.4 ft/sec.). Pressure distributions are presented for single and dual jets over a range of velocity ratios from 2 to 10, spacings from 2 to 6 diameters and injection angles of 90, 75, 60, and 105 degrees. For the body of revolution tests, the ratio of the jet to body diameters was set as large (1/2) in order to be more representative of V/STOL aircraft applications. Flat plate tests involved dual jets both aligned and in side by side configurations. The effects of the various parameters and the differences between the axisymmetric and planar body geometrics on the nature, size, shape, and strength of the interaction regions on the body surfaces are shown. Some flowfield measurements are also presented, and it is shown that a simple analysis is capable of predicting the trajectories of the jets.

  4. Combined effect of buoyancy force and Navier slip on MHD flow of a nanofluid over a convectively heated vertical porous plate.

    Science.gov (United States)

    Mutuku-Njane, Winifred Nduku; Makinde, Oluwole Daniel

    2013-01-01

    We examine the effect of magnetic field on boundary layer flow of an incompressible electrically conducting water-based nanofluids past a convectively heated vertical porous plate with Navier slip boundary condition. A suitable similarity transformation is employed to reduce the governing partial differential equations into nonlinear ordinary differential equations, which are solved numerically by employing fourth-order Runge-Kutta with a shooting technique. Three different water-based nanofluids containing copper (Cu), aluminium oxide (Al2O3), and titanium dioxide (TiO2) are taken into consideration. Graphical results are presented and discussed quantitatively with respect to the influence of pertinent parameters, such as solid volume fraction of nanoparticles (φ), magnetic field parameter (Ha), buoyancy effect (Gr), Eckert number (Ec), suction/injection parameter (f w ), Biot number (Bi), and slip parameter ( β ), on the dimensionless velocity, temperature, skin friction coefficient, and heat transfer rate.

  5. Chemical reaction and radiation effects on the transient MHD free convection flow of dissipative fluid past an infinite vertical porous plate with ramped wall temperature

    Directory of Open Access Journals (Sweden)

    V. RAJESH

    2011-06-01

    Full Text Available A finite-difference analysis is performed to study the effects of thermal radiation and chemical reaction on the transient MHD free convection and mass transform flow of a dissipative fluid past an infinite vertical porous plate subject to ramped wall temperature. The fluid considered here is a gray, absorbing/ /emitting radiation but a non-scattering medium. The dimensionless governing equations are unsteady, coupled and non-linear partial differential equations. An analytical method fails to give a solution. Hence an implicit finite difference scheme of Crank-Nicolson method is employed. The effect of the magnetic parameter (M, chemical reaction parameter (K, radiation parameter (F, buoyancy ratio parameter (N, Schmidt number (Sc on the velocity field and skin friction for both air (Pr = 0.71 and water (Pr = 7 in the presence of both aiding (N>0 and opposing (N<0 flows are extensively discussed with the help of graphs.

  6. The influence of chemical reaction and viscous dissipation on unsteady MHD free convection flow past an exponentially accelerated vertical plate with variable surface conditions

    Directory of Open Access Journals (Sweden)

    Kishore P.M.

    2013-01-01

    Full Text Available A numerical study is presented on the effects of chemical reaction and magnetic field on the unsteady free convection flow, heat and mass transfer characteristics in a viscous, incompressible and electrically conducting fluid past an exponentially accelerated vertical plate by taking into account the heat due to viscous dissipation. The problem is governed by coupled non-linear partial differential equations. The dimensionless equations of the problem have been solved numerically by the implicit finite difference method of Crank - Nicolson’s type. The effects of governing parameters on the flow variables are discussed quantitatively with the aid of graphs for the flow field, temperature field, concentration field, skin-friction, Nusselt number and Sherwood number. It is found that under the influence of chemical reaction, the flow velocity as well as concentration distributions reduce, while the viscous dissipation parameter leads to increase the temperature.

  7. Heat and mass transfer effects on the mixed convective flow of chemically reacting nanofluid past a moving/stationary vertical plate

    Directory of Open Access Journals (Sweden)

    B. Mahanthesh

    2016-03-01

    Full Text Available The problem of conjugate effects of heat and mass transfer over a moving/stationary vertical plate has been studied under the influence of applied magnetic field, thermal radiation, internal heat generation/absorption and first order chemical reaction. The fluid is assumed to be electrically conducting water based Cu-nanofluid. The Tiwari and Das model is used to model the nanofluid, whereas Rosseland approximation is used for thermal radiation effect. Unified closed form solutions are obtained for the governing equations using Laplace transform method. The velocity, temperature and concentration profiles are expressed graphically for different flow pertinent parameters. The physical quantities of engineering interest such as skin friction, Nusselt number and Sherwood number are also computed. The obtained analytical solutions satisfy all imposed initial and boundary conditions and they can be reduced to known previous results in some limiting cases. It is found that, by varying nanoparticle volume fraction, the flow and heat transfer characteristics could be controlled.

  8. Radiation and porosity effects on the magnetohydrodynamic flow near a vertical plate that applies shear stress to the fluid with mass diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Arshad; Khan, Ilyas; Shafie, Sharidan [Faculty of Science, Universiti Teknologi Malaysia (Malaysia)

    2014-06-19

    This article studies the radiation and porosity effects on the unsteady magnetohydrodynamic free convection flow of an incompressible viscous fluid past an infinite vertical plate that applies a shear stress f(t) to the fluid. Conjugate phenomenon of heat and mass transfer is considered. General solutions of the dimensionless governing equations along with imposed initial and boundary conditions are determined using Laplace transform technique. The solution of velocity is presented as a sum of mechanical and non mechanical parts. These solutions satisfy all imposed initial and boundary conditions and reduce to some known solutions from the literature as special cases. The results for embedded parameters are shown graphically. Numerical results for skin friction, Nusselt number and Sherwood number are computed and presented in tabular forms.

  9. Second-order velocity slip with axisymmetric stagnation point flow and heat transfer due to a stretching vertical plate in a Copper-water nanofluid

    Science.gov (United States)

    Kardri, M. A.; Bachok, N.; Arifin, N. M.; Ali, F. M.

    2017-09-01

    The steady axisymmetric stagnation point flow with second-order velocity slip due to a stretching vertical plate with the existence of copper-water nanofluid was investigated. Similarity transformation has been applied to reduce the governing partial differential equations to ordinary differential equations. Then the self-similar equations are solved numerically using solver bvp4c available in Matlab with Prandtl number, Pr = 6.2. It is found that the dual solutions exist for the certain range of mixed convection parameter. The effects of the governing parameters on the velocity and temperature profile, skin friction coefficient and the local Nusselt number are observed. The results show that the inclusion of nanoparticle copper, will increase the shear stress on the stretching sheet and decrease the heat transfer rate for the slip parameters.

  10. Some Exact Solutions of Boundary Layer Flows along a Vertical Plate with Buoyancy Forces Combined with Lorentz Forces under Uniform Suction

    Directory of Open Access Journals (Sweden)

    Asterios Pantokratoras

    2008-01-01

    Full Text Available Exact analytical solutions of boundary layer flows along a vertical porous plate with uniform suction are derived and presented in this paper. The solutions concern the Blasius, Sakiadis, and Blasius-Sakiadis flows with buoyancy forces combined with either MHD Lorentz or EMHD Lorentz forces. In addition, some exact solutions are presented specifically for water in the temperature range of 0∘C≤≤8∘C, where water density is nearly parabolic. Except for their use as benchmarking means for testing the numerical solution of the Navier-Stokes equations, the presented exact solutions with EMHD forces have use in flow separation control in aeronautics and hydronautics, whereas the MHD results have applications in process metallurgy and fusion technology. These analytical solutions are valid for flows with strong suction.

  11. Computational study of Jeffrey’s non-Newtonian fluid past a semi-infinite vertical plate with thermal radiation and heat generation/absorption

    Directory of Open Access Journals (Sweden)

    S. Abdul Gaffar

    2017-06-01

    Full Text Available The nonlinear, steady state boundary layer flow, heat and mass transfer of an incompressible non-Newtonian Jeffrey’s fluid past a semi-infinite vertical plate is examined in this article. The transformed conservation equations are solved numerically subject to physically appropriate boundary conditions using a versatile, implicit finite-difference Keller box technique. The influence of a number of emerging non-dimensional parameters, namely Deborah number (De, ratio of relaxation to retardation times (λ, Buoyancy ratio parameter (N, suction/injection parameter (fw, Radiation parameter (F, Prandtl number (Pr, Schmidt number (Sc, heat generation/absorption parameter (Δ and dimensionless tangential coordinate (ξ on velocity, temperature and concentration evolution in the boundary layer regime is examined in detail. Also, the effects of these parameters on surface heat transfer rate, mass transfer rate and local skin friction are investigated. This model finds applications in metallurgical materials processing, chemical engineering flow control, etc.

  12. Radiation and mass transfer effects on an unsteady MHD free convection flow past a heated vertical plate in a porous medium with viscous dissipation

    Directory of Open Access Journals (Sweden)

    Prasad Ramachandra V.

    2007-01-01

    Full Text Available An unsteady, two-dimensional, hydromagnetic, laminar free convective boundary-layer flow of an incompressible, Newtonian, electrically-conducting and radiating fluid past an infinite heated vertical porous plate with heat and mass transfer is analyzed, by taking into account the effect of viscous dissipation. The dimensionless governing equations for this investigation are solved analytically using two-term harmonic and non-harmonic functions. Numerical evaluation of the analytical results is performed and graphical results for velocity, temperature and concentration profiles within the boundary layer and tabulated results for the skin-friction coefficient, Nusselt number and Sherwood number are presented and discussed. It is observed that, when the radiation parameter increases, the velocity and temperature decrease in the boundary layer, whereas when thermal and solutal Grashof increases the velocity increases.

  13. The vertical ground reaction force and the pressure distribution on the claws of dairy cows while walking on a flat substrate

    NARCIS (Netherlands)

    Tol, van der P.P.J.; Metz, J.H.M.; Noordhuizen-Stassen, E.N.; Back, W.; Braam, C.R.; Weijs, W.A.

    2003-01-01

    The pressure distribution under the bovine claw while walking was measured to test the hypotheses that the vertical ground reaction force is unevenly distributed and makes some (regions of the) claws more prone to injuries due to overloading than others. Each limb of nine recently trimmed Holstein

  14. The effects of thermal radiation and viscous dissipation on MHD heat and mass diffusion flow past an oscillating vertical plate embedded in a porous medium with variable surface conditions

    Directory of Open Access Journals (Sweden)

    Kishore P.M.

    2012-01-01

    Full Text Available This investigation is undertaken to study the hydromagnetic flow of a viscous incompressible fluid past an oscillating vertical plate embedded in a porous medium with radiation, viscous dissipation and variable heat and mass diffusion. Governing equations are solved by unconditionally stable explicit finite difference method of DuFort - Frankel’s type for concentration, temperature, vertical velocity field and skin - friction and they are presented graphically for different values of physical parameters involved. It is observed that plate oscillation, variable mass diffusion, radiation, viscous dissipation and porous medium affect the flow pattern significantly.

  15. Numerical investigation of MHD free convection flow of a non-Newtonian fluid past an impulsively started vertical plate in the presence of thermal diffusion and radiation absorption

    Directory of Open Access Journals (Sweden)

    M. Umamaheswar

    2016-09-01

    Full Text Available A numerical investigation is carried out on an unsteady MHD free convection flow of a well-known non-Newtonian visco elastic second order Rivlin-Erickson fluid past an impulsively started semi-infinite vertical plate in the presence of homogeneous chemical reaction, thermal radiation, thermal diffusion, radiation absorption and heat absorption with constant mass flux. The presence of viscous dissipation is also considered at the plate under the influence of uniform transverse magnetic field. The flow is governed by a coupled nonlinear system of partial differential equations which are solved numerically by using finite difference method. The effects of various physical parameters on the flow quantities viz. velocity, temperature, concentration, Skin friction, Nusselt number and Sherwood number are studied numerically. The results are discussed with the help of graphs. We observed that the velocity decreases with an increase in magnetic field parameter, Schmidt number, and Prandtl number while it increases with an increase in Grashof number, modified Grashof number, visco-elastic parameter and Soret number. Temperature increases with an increase in radiation absorption parameter, Eckert number and visco-elastic parameter while it decreases with increasing values of radiation parameter, Prandtl number and heat absorption parameter. Concentration increases with increase in Soret number while it decreases with an increase in Schmidt number and chemical reaction parameter.

  16. A Comparative Study of Weights and Sizes of Flat-Plate Exhaust-Gas-to-Air Heat Exchangers with and without Fins

    Science.gov (United States)

    1947-07-01

    with tho naao also o.’.r -nd oxhauat-gac pc40~3i. gapa . H-ductlona in volght and volicio with flat In tbj air pecsagoa only ar^ not 90 largj a3 occur...it la noceaaory to incroasG tho gca-paesago gapa , thereby increraing tho no-flow uiaoneion, lB. A,s< indicated by equation (S)# an increaso in tie no

  17. Influence of the elliptical and circular orifices on the local heat transfer distribution of a flat plate impinged by under-expanded jets

    Science.gov (United States)

    Vinze, Ravish; Limeye, M. D.; Prabhu, S. V.

    2017-04-01

    Experimental study is carried out to explore the influence of nozzle profile on heat transfer for underexpanded impinging jets. Circular and elliptical orifices are used to generate underexpanded jets for underexpantion ratio ranging from 1.25 to 2.67. The supply pressure maintained in the present study ranges from 2.36 to 5.08 times the ambient pressure. IR thermal imaging camera is used to measure surface temperature of thin foil at different nozzle to plate distances. Shadowgraph and pressure distribution are used to understand the flow structure and distribution of circular and elliptical nozzle. It is observed that plate shock and pressure distribution over the plate have significant influence on the local heat transfer. The performance of the circular orifice is far better at lower z/d. The axis switching is observed for an elliptical orifice. Correlation for local heat transfer predicts Nusselt number comparable within 15 % of experimental results.

  18. Effects of Ramped Wall Temperature on Unsteady Two-Dimensional Flow Past a Vertical Plate with Thermal Radiation and Chemical Reaction

    Directory of Open Access Journals (Sweden)

    V. Rajesh

    2014-08-01

    Full Text Available The interaction of free convection with thermal radiation of a viscous incompressible unsteady flow past a vertical plate with ramped wall temperature and mass diffusion is presented here, taking into account the homogeneous chemical reaction of first order. The fluid is gray, absorbing-emitting but non-scattering medium and the Rosseland approximation is used to describe the radiative flux in the energy equation. The dimensionless governing equations are solved using an implicit finite-difference method of the Crank-Nicolson type, which is stable and convergent. The velocity profiles are compared with the available theoretical solution and are found to be in good agreement. Numerical results for the velocity, the temperature, the concentration, the local and average skin friction, the Nusselt number and Sherwood number are shown graphically. This work has wide application in chemical and power engineering and also in the study of vertical air flow into the atmosphere. The present results can be applied to an important class of flows in which the driving force for the flow is provided by combination of the thermal and chemical species diffusion effects.

  19. MHD mixed convection flow of power law non-Newtonian fluids over an isothermal vertical wavy plate

    Energy Technology Data Exchange (ETDEWEB)

    Mirzaei Nejad, Mehrzad [Faculty of Mechanical Engineering, University of Guilan, P.O. Box 3756, Rasht (Iran, Islamic Republic of); Javaherdeh, K., E-mail: Javaherdeh@guilan.ac.ir [Faculty of Mechanical Engineering, University of Guilan, P.O. Box 3756, Rasht (Iran, Islamic Republic of); Moslemi, M. [Ayandegan Institute of Higher Education, Tonekabon (Iran, Islamic Republic of)

    2015-09-01

    Mixed convection flow of electrically conducting power law fluids along a vertical wavy surface in the presence of a transverse magnetic field is studied numerically. Prandtl coordinate transformation together with the spline alternating direction implicit method is employed to solve the boundary layer equations. The influences of both flow structure and dominant convection mode on the overall parameters of flow and heat transfer are well discussed. Also, the role of magnetic field in controlling the boundary layers is investigated. The variation of Nusselt number and skin friction coefficient are studied as functions of wavy geometry, magnetic field, buoyancy force and material parameters. Results reveal the interrelation of the contributing factors. - Highlights: • Magnetic field effects undermine the heat transfer for n<1 more markedly. • Magnetic field decreases the values of Nu number and C{sub f} downstream of the plat. • The magnetic field opposes the second harmonic in the curve of Nu number and C{sub f}. • The wavy geometry influences the pseudo-plastic fluids (n<1) more profoundly.

  20. Experimental analysis of solar thermal integrated MD system for cogeneration of drinking water and hot water for single family villa in dubai using flat plate and evacuated tube solar collectors

    DEFF Research Database (Denmark)

    Asim, Muhammad; Imran, Muhammad; Leung, Michael K.H.

    2017-01-01

    This paper presents the experimental analysis performed on solar thermal integrated membrane distillation (MD) system using flat plate and evacuated tube collectors. The system will be utilized for cogeneration of drinking water and domestic hot water for single family in Dubai comprising of four...... on MD setup at optimized flow rates of 6 L/min on hot side and 3 L/min on cold side for producing the desired distillate. The hot side and cold side MD temperature has been maintained between 60°C and 70°C, and 20°C and 30°C. The total annual energy demand comes out to be 8,223 kWh (6,000 k...

  1. Studies of flat-plate solar air collectors with absorber plates made of amorphous silicon photovoltaic modules; Amorphous taiyo denchi module wo shunetsuban to shita heibangata kukishiki shunetsuki no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Ito, S.; Miura, N. [Kanagawa Institute of Technology, Kanagawa (Japan)

    1996-10-27

    A light/heat hybrid air type heat collector has been developed in which heat is collected by solar cell panels. In Type 1 heat collector provided with a glass cover, two modules are connected in series and placed under a glass cover to serve as a heat collecting plate, each module built of a steel plate and two thin-film amorphous solar cells bonded to the steel plate. Air runs under the heat collecting plate. Type 2 heat collector is a Type 1 heat collector minus the glass cover. Air is taken in by a fan, runs in a vinyl chloride tube, and then through the heat collector where it is heated by the sun, and goes out at the exit. Heat collecting performance was subjected to theoretical analysis. This heat collector approximated in point of heat collection a model using a board painted black, which means that the new type functions effectively as an air-type heat collector. Operating as a photovoltaic power generator, the covered type generated approximately 20% less than the uncovered type under 800W/m{sup 2} insolation conditions. Type 1 has been in service for five months, and Type 2 for 2 months. At present, both are free of troubles such as deformation and the amorphous solar cell modules have deteriorated but a little. 4 refs., 9 figs.

  2. An exact solution on unsteady MHD free convection chemically reacting silver nanofluid flow past an exponentially accelerated vertical plate through porous medium

    Science.gov (United States)

    Kumaresan, E.; Vijaya Kumar, A. G.; Rushi Kumar, B.

    2017-11-01

    This article studies, an exact solution of unsteady MHD free convection boundary-layer flow of a silver nanofluid past an exponentially accelerated moving vertical plate through aporous medium in the presence of thermal radiation, transverse applied amagnetic field, radiation absorption and Heat generation or absorption with chemical reaction are investigated theoretically. We consider nanofluids contain spherical shaped nanoparticle of silverwith a nanoparticle volume concentration range smaller than or equal to 0.04. This phenomenon is modeled in the form of partial differential equations with initial boundary conditions. Some suitable dimensional variables are introduced. The corresponding dimensionless equations with boundary conditions are solved by using Laplace transform technique. The exact solutions for velocity, energy, and species are obtained, also the corresponding numerical values of nanofluid velocity, temperature and concentration profiles are represented graphically. The expressions for skin friction coefficient, the rate of heat transfer and mass transfer are derived. The present study finds applications involving heat transfer, enhancement of thermal conductivity and other applications like transportation, industrial cooling applications, heating buildings and reducing pollution, energy applications and solar absorption. The effect of heat transfer is found to be more pronounced in a silver–water nanofluid than in the other nanofluids.

  3. Comparison of intraoperative flat panel imaging and postoperative plain radiography for the detection of intraarticular screw displacement in volar distal radius plate ostheosynthesis.

    Science.gov (United States)

    Borggrefe, J; Bolte, H; Worms, W; Mahlke, L; Seekamp, A; Menzdorf, L; Varoga, D; Müller, M; Weuster, M; Zorenkov, D; Wedel, T; Lippross, S

    2015-12-01

    To investigate if intraoperative 3D flat panel imaging improves the detection of radiocarpal intraarticular screw misplacement (RCSM) in comparison to standard postoperative x-ray. In a study on cadaver specimens, we evaluated the sensitivity and specificity to detect RCSM using X-ray, intraoperative 3D-fluoroscopy as well as the digital volume tomography. The gold standard reference was computed tomography. Sensitivity for the detection of RCSM for X-ray was 58% and specificity 88%. For DVT, the sensitivity to detect RCSM was 88% and the specificity 53%. For 3D-fluoroscopy, the sensitivity for RCSM was 68% and specificity 95%. When combining the methods, the best performance was found, when combining the two intraoperative imaging methods, with a resulting sensitivity of 88% and a specificity of 73%. Intraoperative 3D fluoroscopy and digital volume tomography appear to be at least as sensitive and specific to detect RCSM than the regular postoperative radiography in two planes. However, especially discrete screw misplacements can be missed with either method. Level IV. Diagnostic device study. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  4. Combined natural convection and mass transfer effects on unsteady flow past an infinite vertical porous plate embedded in a porous medium with heat source

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.S. [Department of Physics, K B D A V College, Nirakarpur, Khurda-752 019 (Orissa) (India); Tripathy, R.K. [Department of Physics, D R Nayapalli College, Bhubaneswar-751 012 (Orissa) (India); Padhy, R.K. [Department of Physics, D A V Public School, Chandrasekharpur, Bhubaneswar-751 021 (Orissa) (India); Sahu, M. [Department of Physics, Jupiter +2 Women’s Science College, IRC Village, Bhubaneswar-751 015 (Orissa) (India)

    2012-07-01

    This paper theoretically investigates the combined natural convection and mass transfer effects on unsteady flow of a viscous incompressible fluid past an infinite vertical porous plate embedded in a porous medium with heat source. The governing equations of the flow field are solved analytically for velocity, temperature, concentration distribution, skin friction and the rate of heat transfer using multi parameter perturbation technique and the effects of the flow parameters such as permeability parameter Kp, Grashof number for heat and mass transfer Gr, Gc; heat source parameter S, Schmidt number Sc, Prandtl number Pr etc. on the flow field are analyzed and discussed with the help of figures and tables. The permeability parameter Kp is reported to accelerate the transient velocity of the flow field at all points for small values of Kp (£1) and for higher values the effect reverses. The effect of increasing Grashof numbers for heat and mass transfer or heat source parameter is to enhance the transient velocity of the flow field at all points while a growing Schmidt number retards its effect at all points. A growing permeability parameter or heat source parameter increases the transient temperature of the flow field at all points, while a growing Prandtl number shows reverse effect. The effect of increasing Schmidt number is to decrease the concentration boundary layer thickness of the flow field at all points. Further, a growing permeability parameter enhances the skin friction at the wall and a growing Prandtl number shows reverse effect. The effect of increasing Prandtl number or permeability parameter leads to increase the magnitude of the rate of heat transfer at the wall.

  5. The Radiation Problem from a Vertical Hertzian Dipole Antenna above Flat and Lossy Ground: Novel Formulation in the Spectral Domain with Closed-Form Analytical Solution in the High Frequency Regime

    Directory of Open Access Journals (Sweden)

    K. Ioannidi

    2014-01-01

    Full Text Available We consider the problem of radiation from a vertical short (Hertzian dipole above flat lossy ground, which represents the well-known “Sommerfeld radiation problem” in the literature. The problem is formulated in a novel spectral domain approach, and by inverse three-dimensional Fourier transformation the expressions for the received electric and magnetic (EM field in the physical space are derived as one-dimensional integrals over the radial component of wavevector, in cylindrical coordinates. This formulation appears to have inherent advantages over the classical formulation by Sommerfeld, performed in the spatial domain, since it avoids the use of the so-called Hertz potential and its subsequent differentiation for the calculation of the received EM field. Subsequent use of the stationary phase method in the high frequency regime yields closed-form analytical solutions for the received EM field vectors, which coincide with the corresponding reflected EM field originating from the image point. In this way, we conclude that the so-called “space wave” in the literature represents the total solution of the Sommerfeld problem in the high frequency regime, in which case the surface wave can be ignored. Finally, numerical results are presented, in comparison with corresponding numerical results based on Norton’s solution of the problem.

  6. Irreversibility analysis of non isothermal flat plate solar collectors for air heating with a dimensionless model; Analisis de las irreversibilidades en colectores solares de placas planas no isotermicos para calentamiento de aire utilizando un modelo adimensional

    Energy Technology Data Exchange (ETDEWEB)

    Bracamonte-Baran, Johane Hans; Baritto-Loreto, Miguel Leonardo [Universidad Central de Venezuela (Venezuela)]. E-mails: johanehb@gmail.com; johane.bracamonte@ucv.ve; miguel.baritto@ucv.ve

    2013-04-15

    The dimensionless model developed and validated by Baritto and Bracamonte (2012) for the thermal behavior of flat plate solar collector without glass cover is improved by adding the entropy balance equation in a dimensionless form. The model is solved for a wide range of aspect ratios and mass flow numbers. A parametric study is developed and the distribution of internal irreversibilities along the collector is analyzed. The influence of the design parameters on the entropy generation by fluid friction and heat transfer is analyzed and it is found that for certain combinations of these parameters optimal thermodynamic operation can be achieved. [Spanish] En el presente trabajo, el modelo adimensional desarrollado y validado por Baritto y Bracamonte (2012) para describir el comportamiento termico de colectores solares de placas planas sin cubierta transparente, se complementa con la ecuacion adimensional de balance de entropia para un elemento diferencial de colector solar. El modelo se resuelve para un amplio rango de valores de relaciones de aspecto y numero de flujo de masa. A partir de los resultados del modelo se desarrolla un analisis detallado de la influencia de estos parametros sobre la distribucion de irreversibilidades internas a lo largo del colector. Adicionalmente se estudia la influencia de estos parametros sobre los numeros de generacion de entropia por friccion viscosa, por transferencia de calor y total. Se encuentra que existen combinaciones de los parametros antes mencionados, para los cuales, la operacion del colector es termodinamicamente optima para numeros de flujo de masa elevados.

  7. A flat solar collector built from galvanized steel plate, working by thermosyphonic flow, optimized for Mexican conditions; Un colector solar plano construido de lamina de acero galvanizada, operando por flujo termosifonico, optimizado para las condiciones mexicanas

    Energy Technology Data Exchange (ETDEWEB)

    Marroquin de Jesus, A; Olivares Ramirez, J.M.; Ramos Lopez, G.A.; Pless, R.C. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Instituto Politecnico Nacional, Unidad Queretaro (Mexico)]. E-mail: amarroquind@utsjr.edu.mx

    2009-07-15

    Design, construction, and testing of the thermal performance of a flat solar collector for domestic water heating are described. The absorbing plate is built from readily available materials: two sheets of galvanized steel, one of the channelled types, the other one flat, which are joined by electric welding. The absorber is connected to a 198-L thermotank, insulated with polyurethane foam. In terms of receiving surface, the prototype tested here has an area of 1.35 m{sup 2}, about 20% smaller than comparable copper-tube-based collectors offered in the market. Temperature measurements conducted over a 30-day period gave values which were a few degrees lower than the theoretically calculated water temperatures. Momentary thermal efficiency values between 35% and 77% were observed. The water temperature achieved the tank at the end of the day averages 65 degrees Celsius in winter weather conditions in the central Mexican highland. This design of solar water heater is well suited to Mexican conditions, as it makes use of the high local intensity of the solar radiation, and as the channel shape of the ducts minimizes bursting during the rare occurrences of freezing temperatures in the region; it also has the advantage of being manufacturable at low cost from simple materials. [Spanish] Se describe el diseno, construccion y pruebas del desempeno termico de un colector solar plano para calentamiento de agua para uso domestico. La placa absorbedora se construyo de materiales facilmente asequibles: dos placas de acero galvanizado, una del tipo acanalado y la otra plana, unidas mediante soldadura de acero electrico. La placa absorbedora esta conectada a un termotanque con capacidad de 198 L, aislado con espuma de poliuretano. La superficie receptora de este prototipo es de 1.35 m{sup 2}, aproximadamente 20% mas pequena comparado con los colectores, basados en tubos de cobre, ofertados en el mercado. Mediciones de temperatura por un periodo de 30 dias, arrojaron valores

  8. Surface heat flux feedback controlled impurity seeding experiments with Alcator C-Mod’s high-Z vertical target plate divertor: performance, limitations and implications for fusion power reactors

    Science.gov (United States)

    Brunner, D.; Wolfe, S. M.; LaBombard, B.; Kuang, A. Q.; Lipschultz, B.; Reinke, M. L.; Hubbard, A.; Hughes, J.; Mumgaard, R. T.; Terry, J. L.; Umansky, M. V.; The Alcator C-Mod Team

    2017-08-01

    The Alcator C-Mod team has recently developed a feedback system to measure and control surface heat flux in real-time. The system uses real-time measurements of surface heat flux from surface thermocouples and a pulse-width modulated piezo valve to inject low-Z impurities (typically N2) into the private flux region. It has been used in C-Mod to mitigate peak surface heat fluxes  >40 MW m-2 down to    1. While the system works quite well under relatively steady conditions, use of it during transients has revealed important limitations on feedback control of impurity seeding in conventional vertical target plate divertors. In some cases, the system is unable to avoid plasma reattachment to the divertor plate or the formation of a confinement-damaging x-point MARFE. This is due to the small operational window for mitigated heat flux in the parameters of incident plasma heat flux, plasma density, and impurity density as well as the relatively slow response of the impurity gas injection system compared to plasma transients. Given the severe consequences for failure of such a system to operate reliably in a reactor, there is substantial risk that the conventional vertical target plate divertor will not provide an adequately controllable system in reactor-class devices. These considerations motivate the need to develop passively stable, highly compliant divertor configurations and experimental facilities that can test such possible solutions.

  9. Flat-plate photovoltaic array design optimization

    Science.gov (United States)

    Ross, R. G., Jr.

    1980-01-01

    An analysis is presented which integrates the results of specific studies in the areas of photovoltaic structural design optimization, optimization of array series/parallel circuit design, thermal design optimization, and optimization of environmental protection features. The analysis is based on minimizing the total photovoltaic system life-cycle energy cost including repair and replacement of failed cells and modules. This approach is shown to be a useful technique for array optimization, particularly when time-dependent parameters such as array degradation and maintenance are involved.

  10. GROUND REACTION FORCE DIFFERENCES BETWEEN RUNNING SHOES, RACING FLATS, AND DISTANCE SPIKES IN RUNNERS

    Directory of Open Access Journals (Sweden)

    Suzanna Logan

    2010-03-01

    Full Text Available Various shoes are worn by distance runners throughout a training season. This study measured the differences in ground reaction forces between running shoes, racing flats, and distance spikes in order to provide information about the potential effects of footwear on injury risk in highly competitive runners. Ten male and ten female intercollegiate distance runners ran across a force plate at 6.7 m·s-1 (for males and 5.7 m·s-1 (for females in each of the three types of shoes. To control for differences in foot strike, only subjects who exhibited a heel strike were included in the data analysis. Two repeated-measures ANOVAs with Tukey's post-hoc tests (p < 0.05 were used to detect differences in shoe types among males and females. For the males, loading rate, peak vertical impact force and peak braking forces were significantly greater in flats and spikes compared to running shoes. Vertical stiffness in spikes was also significantly greater than in running shoes. Females had significantly shorter stance times and greater maximum propulsion forces in racing flats compared to running shoes. Changing footwear between the shoes used in this study alters the loads placed on the body. Care should be taken as athletes enter different phases of training where different footwear is required. Injury risk may be increased since the body may not be accustomed to the differences in force, stance time, and vertical stiffness

  11. Necessity of the Ridge for the Flat Slab Subduction: Insights from the Peruvian Flat Slab

    Science.gov (United States)

    Knezevic Antonijevic, S.; Wagner, L. S.; Beck, S. L.; Long, M. D.; Zandt, G.; Tavera, H.

    2014-12-01

    Flattening of the subducting plate has been linked to the formation of various geological features, including basement-cored uplifts, the cessation of arc volcanism, ignimbrite flare-ups, and the formation of high plateaus and ore deposits [Humphreys et al., 2003; Gutscher et al., 2000; Rosenbaum et al., 2005]. However, the mechanism responsible for the slab flattening is still poorly understood. Here we focus on the Peruvian flat slab, where the Nazca plate starts to bend at ~80 km depth and travels horizontally for several hundred kilometers, at which point steep subduction resumes. Based on a 1500 km long volcanic gap and intermediate depth seismicity patterns, the Peruvian flat slab appears to have the greatest along-strike extent and, therefore, has been suggested as a modern analogue to the putative flat slab during the Laramide orogeny in the western United States (~80-55 Ma). Combining 3D shear wave velocity structure and Rayleigh wave phase anisotropy between ~10° and 18° S, we find that the subducting Nazca plate is not uniformly flat along the entire region, but fails to the north of the subducting Nazca Ridge. Our results show that, in combination with trench retreat, rapid overriding plate motion, and/or presence of a thick cratonic root, the subduction of buoyant overthickened oceanic crust, such as the Nazca Ridge, is necessary for the formation and sustainability of flat slabs. This finding has important implications for the formation of flat slabs both past and present.

  12. Vertical GPS ground motion rates in the Euro-Mediterranean region: New evidence of velocity gradients at different spatial scales along the Nubia-Eurasia plate boundary

    OpenAIRE

    Serpelloni, Enrico; Faccenna, Claudio; Spada, Giorgio; DONG Danan; Williams, Simon D.P.

    2013-01-01

    We use 2.5 to 14 years long position time series from >800 continuous Global Positioning System (GPS) stations to study vertical deformation rates in the Euro-Mediterranean region. We estimate and remove common mode errors in position time series using a principal component analysis, obtaining a significant gain in the signal-to-noise ratio of the displacements data. Following the results of a maximum likelihood estimation analysis, which gives a mean spectral index ~ −0.7, we adopt a power l...

  13. Influence of non-integer order parameter and Hartmann number on the heat and mass transfer flow of a Jeffery fluid over an oscillating vertical plate via Caputo-Fabrizio time fractional derivatives

    Science.gov (United States)

    Butt, A. R.; Abdullah, M.; Raza, N.; Imran, M. A.

    2017-10-01

    In this work, semi analytical solutions for the heat and mass transfer of a fractional MHD Jeffery fluid over an infinite oscillating vertical plate with exponentially heating and constant mass diffusion via the Caputo-Fabrizio fractional derivative are obtained. The governing equations are transformed into dimensionless form by introducing dimensionless variables. A modern definition of the Caputo-Fabrizio derivative has been used to develop the fractional model for a Jeffery fluid. The expressions for temperature, concentration and velocity fields are obtained in the Laplace transformed domain. We have used the Stehfest's and Tzou's algorithm for the inverse Laplace transform to obtain the semi analytical solutions for temperature, concentration and velocity fields. In the end, in order to check the physical impact of flow parameters on temperature, concentration and velocity fields, results are presented graphically and in tabular forms.

  14. Thermal transport between a continuously moving heated plate and a quiescent ambient medium

    Science.gov (United States)

    Karwe, Mukund Vishnu

    A numerical and experimental investigation of the heat transfer and the fluid flow associated with a continuously moving flat surface was carried out. This circumstance is encountered in manufacturing processes such as hot rolling, extrusion, and continuous casting. The resulting temperature distribution within the solid, the appropriate conditions that arise at the location where the plate emerges from the furnace of the die, and the nature of the induced flow field and the heat transfer rate, are of interest. These considerations are important in the simulation, design, control, and optimization of the practical systems. In the numerical part of the study, the thermal transport from a flat, infinitely wide, continuously moving plate, was studied assuming a two-dimensional steady circumstance. The boundary layer equations as well as full governing equations, including buoyancy effects, were solved employing finite difference techniques. Conjugate transport, involving conduction within the plate, radiative loss from the plates surface and convection to the fluid, was considered. The temperature measurements were carried out for a heated aluminum plate moving vertically downward in water and moving upward or downward in the air. The temperature distributions, within the moving plate and the induced flow, were measured, using a microcomputer-controlled data acquisition system. The flow was visualized by means of a shadowgraph.

  15. Heat and Mass Transfer of Unsteady Hydromagnetic Free Convection Flow Through Porous Medium Past a Vertical Plate with Uniform Surface Heat Flux

    Science.gov (United States)

    El-Aziz, Mohamed Abd; Yahya, Aishah S.

    2017-09-01

    Simultaneous effects of thermal and concentration diffusions in unsteady magnetohydrodynamic free convection flow past a moving plate maintained at constant heat flux and embedded in a viscous fluid saturated porous medium is presented. The transport model employed includes the effects of thermal radiation, heat sink, Soret and chemical reaction. The fluid is considered as a gray absorbing-emitting but non-scattering medium and the Rosseland approximation in the energy equations is used to describe the radiative heat flux for optically thick fluid. The dimensionless coupled linear partial differential equations are solved by using Laplace transform technique. Numerical results for the velocity, temperature, concentration as well as the skin friction coefficient and the rates of heat and mass transfer are shown graphically for different values of physical parameters involved.

  16. Biomechanical stability of a supra-acetabular pedicle screw Internal Fixation device (INFIX vs External Fixation and plates for vertically unstable pelvic fractures

    Directory of Open Access Journals (Sweden)

    Vigdorchik Jonathan M

    2012-09-01

    Full Text Available Abstract Background We have recently developed a subcutaneous anterior pelvic fixation technique (INFIX. This internal fixator permits patients to sit, roll over in bed and lie on their sides without the cumbersome external appliances or their complications. The purpose of this study was to evaluate the biomechanical stability of this novel supraacetabular pedicle screw internal fixation construct (INFIX and compare it to standard internal fixation and external fixation techniques in a single stance pelvic fracture model. Methods Nine synthetic pelves with a simulated anterior posterior compression type III injury were placed into three groups (External Fixator, INFIX and Internal Fixation. Displacement, total axial stiffness, and the stiffness at the pubic symphysis and SI joint were calculated. Displacement and stiffness were compared by ANOVA with a Bonferroni adjustment for multiple comparisons Results The mean displacement at the pubic symphysis was 20, 9 and 0.8 mm for external fixation, INFIX and internal fixation, respectively. Plate fixation was significantly stiffer than the INFIX and external Fixator (P = 0.01 at the symphysis pubis. The INFIX device was significantly stiffer than external fixation (P = 0.017 at the symphysis pubis. There was no significant difference in SI joint displacement between any of the groups. Conclusions Anterior plate fixation is stiffer than both the INFIX and external fixation in single stance pelvic fracture model. The INFIX was stiffer than external fixation for both overall axial stiffness, and stiffness at the pubic symphysis. Combined with the presumed benefit of minimizing the complications associated with external fixation, the INFIX may be a more preferable option for temporary anterior pelvic fixation in situations where external fixation may have otherwise been used.

  17. The critical shear load of rectangular plates

    Science.gov (United States)

    Seydel, Edgar

    1933-01-01

    This report gives formulas for analyzing the critical shear load of a simply supported square, isotropic (simple flat plate), or orthogonal anisotropic plate (a plate in which the rigidity in two directions perpendicular to each other is different, i.e. plywood or corrugated sheet), these formulas, although arrived at by approximation method, seem to agree fairly well with experimental results.

  18. Time dependent Oldroyd-B liquid film flow over an oscillating and porous vertical plate with the effect of thermal radiation

    Science.gov (United States)

    Mohmand, Muhammad Ismail; Shah, Qayyum; Mamat, Mustafa Bin; Shah, Zahir; Khan, Abdul Samad

    2017-05-01

    In the current research work, a liquid film flow of Oldroyd-B fluid with internal heat in vertical porous medium in an oscillating belt is being examined in unsteady state. For this phenomenon, by using basic equations of fluid motion we get a mathematical model. The obtained model problem is solved for the exact analytic solutions by Optimal Homotopy Asymptotic Method (OHAM). Velocity, temperature fields with the mass flow-rate and heat transfer rate of the fluid flow at the belt are also calculated. The effect of pertinent parameters like κ1 relaxation time parameter, κ2 retardation time parameter, Λ porosity parameter, R radiation parameter and Pr temperature fields are also deliberated and then are presented graphically.

  19. Natural convection in a parallel-plate vertical channel with discrete heating by two flush-mounted heaters: effect of the clearance between the heaters

    Science.gov (United States)

    Sarper, Bugra; Saglam, Mehmet; Aydin, Orhan; Avci, Mete

    2017-10-01

    In this study, natural convection in a vertical channel is studied experimentally and numerically. One of the channel walls is heated discretely by two flush-mounted heaters while the other is insulated. The effects of the clearance between the heaters on heat transfer and hot spot temperature while total length of the heaters keeps constant are investigated. Four different settlements of two discrete heaters are comparatively examined. Air is used as the working fluid. The range of the modified Grashof number covers the values between 9.6 × 105 and 1.53 × 10.7 Surface to surface radiation is taken into account. Flow visualizations and temperature measurements are performed in the experimental study. Numerical computations are performed using the commercial CFD code ANSYS FLUENT. The results are represented as the variations of surface temperature, hot spot temperature and Nusselt number with the modified Grashof number and the clearance between the heaters as well as velocity and temperature variations of the fluid.

  20. Plate Tectonics: A Paradigm under Threat.

    Science.gov (United States)

    Pratt, David

    2000-01-01

    Discusses the challenges confronting plate tectonics. Presents evidence that contradicts continental drift, seafloor spreading, and subduction. Reviews problems posed by vertical tectonic movements. (Contains 242 references.) (DDR)

  1. Flat lens for seismic waves

    CERN Document Server

    Brule, Stephane; Guenneau, Sebastien

    2016-01-01

    A prerequisite for achieving seismic invisibility is to demonstrate the ability of civil engineers to control seismic waves with artificially structured soils. We carry out large-scale field tests with a structured soil made of a grid consisting of cylindrical and vertical holes in the ground and a low frequency artificial source (< 10 Hz). This allows the identification of a distribution of energy inside the grid, which can be interpreted as the consequence of an effective negative refraction index. Such a flat lens reminiscent of what Veselago and Pendry envisioned for light opens avenues in seismic metamaterials to counteract the most devastating components of seismic signals.

  2. NATURAL TRANSVERSE VIBRATIONS OF A PRESTRESSED ORTHOTROPIC PLATE-STRIPE

    Directory of Open Access Journals (Sweden)

    Egorychev Oleg Aleksandrovich

    2012-10-01

    Full Text Available The article represents a new outlook at the boundary-value problem of natural vibrations of a homogeneous pre-stressed orthotropic plate-stripe. In the paper, the motion equation represents a new approximate hyperbolic equation (rather than a parabolic equation used in the majority of papers covering the same problem describing the vibration of a homogeneous orthotropic plate-stripe. The proposed research is based on newly derived boundary conditions describing the pin-edge, rigid, and elastic (vertical types of fixing, as well as the boundary conditions applicable to the unfixed edge of the plate. The paper contemplates the application of the Laplace transformation and a non-standard representation of a homogeneous differential equation with fixed factors. The article proposes a detailed representation of the problem of natural vibrations of a homogeneous orthotropic plate-stripe if rigidly fixed at opposite sides; besides, the article also provides frequency equations (no conclusions describing the plate characterized by the following boundary conditions: rigid fixing at one side and pin-edge fixing at the opposite side; pin-edge fixing at one side and free (unfixed other side; rigid fixing at one side and elastic fixing at the other side. The results described in the article may be helpful if applied in the construction sector whenever flat structural elements are considered. Moreover, specialists in solid mechanics and theory of elasticity may benefit from the ideas proposed in the article.

  3. "Flat-Fish" Vacuum Chamber

    CERN Multimedia

    CERN PhotoLab

    1978-01-01

    The picture shows a "Flat-Fish" vacuum chamber being prepared in the ISR workshop for testing prior to installation in the Split Field Magnet (SFM) at intersection I4. The two shells of each part were hydroformed from 0.15 mm thick inconel 718 sheet (with end parts in inconel 600 for easier manual welding to the arms) and welded toghether with two strips which were attached by means of thin stainless steel sheets to the Split Field Magnet poles in order to take the vertical component of the atmospheric pressure force. This was the thinnest vacuum chamber ever made for the ISR. Inconel material was chosen for its high elastic modulus and strenght at chamber bake-out temperature. In this picture the thin sheets transferring the vertical component of the atmosferic pressure force are attached to a support frame for testing. See also 7712182, 7712179.

  4. DESIGN, CONSTRUCTION AND EVALUATION OF A VERTICAL ...

    African Journals Online (AJOL)

    Vertical plate metering device is intended to minimize seed damage during planting while improving metering efficiency and field capacity. A vertical plate maize seed planter which is adapted for gardens and small holder farmers cultivating less than two hectares has been designed, constructed and tested. The major ...

  5. Meiofaunal stratification in relation to microbial food in a tropical mangrove mud flat

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A; Sreepada, R.A; Matondkar, S.G.P.; Parulekar, A

    The vertical gradients of meiofauna mainly in relation to biochemical changes and microbial abundance in the upper 20 cm of deposit of a mangrove mud flat were studied. Strong vertical gradients in the redox potential (Eh), interstitial water...

  6. Weight Consideration in the Design of Absorber Plates | Dama ...

    African Journals Online (AJOL)

    A preliminary investigation (that has to supported later by economic analysis) on the design of an absorber plate for use in a liquid-cooled flat plate solar collector is considered. The objective of the design is to maximize collector efficiency factor, F', while simultaneously minimizing the plate weight. By varying the plate ...

  7. Evaluation of Flat Surface Temperature Probes

    Science.gov (United States)

    Beges, G.; Rudman, M.; Drnovsek, J.

    2011-01-01

    The objective of this paper is elaboration of elements related to metrological analysis in the field of surface temperature measurement. Surface temperature measurements are applicable in many fields. As examples, safety testing of electrical appliances and a pharmaceutical production line represent case studies for surface temperature measurements. In both cases correctness of the result of the surface temperature has an influence on final product safety and quality and thus conformity with specifications. This paper deals with the differences of flat surface temperature probes in measuring the surface temperature. For the purpose of safety testing of electrical appliances, surface temperature measurements are very important for safety of the user. General requirements are presented in European standards, which support requirements in European directives, e.g., European Low Voltage Directive 2006/95/EC and pharmaceutical requirements, which are introduced in official state legislation. This paper introduces a comparison of temperature measurements of an attached thermocouple on the measured surface and measurement with flat surface temperature probes. As a heat generator, a so called temperature artifact is used. It consists of an aluminum plate with an incorporated electrical heating element with very good temperature stability in the central part. The probes and thermocouple were applied with different forces to the surface in horizontal and vertical positions. The reference temperature was measured by a J-type fine-wire (0.2 mm) thermocouple. Two probes were homemade according to requirements in the European standard EN 60335-2-9/A12, one with a fine-wire (0.2 mm) thermocouple and one with 0.5mm of thermocouple wire diameter. Additional commercially available probes were compared. Differences between probes due to thermal conditions caused by application of the probe were found. Therefore, it can happen that measurements are performed with improper equipment or

  8. Numerical Solutions by EFGM of MHD Convective Fluid Flow Past a Vertical Plate Immersed in a Porous Medium in the Presence of Cross Diffusion Effects via Biot Number and Convective Boundary Condition

    Science.gov (United States)

    Raju, R. S.; Reddy, B. M.; Rashidi, M. M.; Gorla, R. S. R.

    2017-08-01

    In this investigation, the numerical results of a mixed convective MHD chemically reacting flow past a vertical plate embedded in a porous medium are presented in the presence of cross diffusion effects and convective boundary condition. Instead of the commonly used conditions of constant surface temperature or constant heat flux, a convective boundary condition is employed which makes this study unique and the results more realistic and practically useful. The momentum, energy, and concentration equations derived as coupled second-order, ordinary differential equations are solved numerically using a highly accurate and thoroughly tested element free Galerkin method (EFGM). The effects of the Soret number, Dufour number, Grashof number for heat and mass transfer, the viscous dissipation parameter, Schmidt number, chemical reaction parameter, permeability parameter and Biot number on the dimensionless velocity, temperature and concentration profiles are presented graphically. In addition, numerical results for the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are discussed through tabular forms. The discussion focuses on the physical interpretation of the results as well as their comparison with the results of previous studies.

  9. Numerical Solutions by EFGM of MHD Convective Fluid Flow Past a Vertical Plate Immersed in a Porous Medium in the Presence of Cross Diffusion Effects via Biot Number and Convective Boundary Condition

    Directory of Open Access Journals (Sweden)

    Raju R.S.

    2017-08-01

    Full Text Available In this investigation, the numerical results of a mixed convective MHD chemically reacting flow past a vertical plate embedded in a porous medium are presented in the presence of cross diffusion effects and convective boundary condition. Instead of the commonly used conditions of constant surface temperature or constant heat flux, a convective boundary condition is employed which makes this study unique and the results more realistic and practically useful. The momentum, energy, and concentration equations derived as coupled second-order, ordinary differential equations are solved numerically using a highly accurate and thoroughly tested element free Galerkin method (EFGM. The effects of the Soret number, Dufour number, Grashof number for heat and mass transfer, the viscous dissipation parameter, Schmidt number, chemical reaction parameter, permeability parameter and Biot number on the dimensionless velocity, temperature and concentration profiles are presented graphically. In addition, numerical results for the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are discussed through tabular forms. The discussion focuses on the physical interpretation of the results as well as their comparison with the results of previous studies.

  10. Numerical calculation of gas and liquid velocities along a vertical flat plate immersed in turbulent tow-phase bubbly flow. Kihoryuchu ni okareta suichoku heiban mawari no ranryu kieki 2 soryu ni kansuru suchi kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, A.; Nakamura, H. (Daido Inst. of Technology, Nagoya (Japan)); Hiraoka, S.; Tada, Y.; Kato, Y. (Nagoya Inst. of Tech. (Japan))

    1993-11-10

    A numerical calculation was made on the bubbly flow using the Prandtl's mixing length theory. The calculation results agreed well with the experimental results in the turbulent flow rather than in the laminar flow. The necessity of discussion on the turbulent flow analysis was clarified. It was elucidated that the experimental results could be explained sufficiently even by the simplest mixing model. The liquid phase velocity vector was aligned on the same direction when the bubbly flow length exceeded 1 cm, and little change took place in the velocity distribution shape. In the analysis of laminar flow, the velocity boundary layer was developed together with tie bubbly flow length, while in the analysis of turbulent flow, such change did not take place. The liquid phase velocity in the vicinity of the inlet had a velocity component which directed to the outside of the wall at the wall side. It was quite different from the analytical result of the laminar flow. The gas phase velocity vector behaved in the similar way to the liquid phase. The velocity direction at the periphery of the velocity distribution in the vicinity of tie inlet was toward the wall surface, and the inlet velocity was rapidly accelerated. 12 refs., 4 figs.

  11. Flat solar captator. procedure for obtaining the surface blackened in the absorber plate (patent awared with bronze medal)photovoltaic generator; Captador solar plano. Procedimiento para la obtencion de superficie ennegrecida en la placa absorbente

    Energy Technology Data Exchange (ETDEWEB)

    Andres Miranda, J. P.

    2010-07-01

    The invention relates to a sensor plane of solar radiation and the procedure for obtaining the blackened surface of the absorber plate. In particular the object that calls the invention consists of a plane collector solar radiation, which applies to air and water heating for both domestic and industrial use, as the main innovative feature is, besides the double glazing for the roof, as channel and its dual capacity of simultaneous water heating and air. the process used to blacken the surface of the absorber plate by the application that incorporates the same graphite or similar conductive material, thus providing it with advantages and innovative features that significantly improve the systems currently known for the same purpose.The scope of the present invention is the industry involved in the manufacture of appliances and devices for the uptake of solar radiation. (Author)

  12. Creating flat design websites

    CERN Document Server

    Pratas, Antonio

    2014-01-01

    This book contains practical, step-by-step tutorials along with plenty of explanation about designing your flat website. Each section is introduced sequentially, building up your web design skills and completing your website.Creating Flat Design Websites is ideal for you if you are starting on your web development journey, but this book will also benefit seasoned developers wanting to start developing in flat.

  13. Hydroelasticity of a Floating Plate

    DEFF Research Database (Denmark)

    Chen, X.; Jensen, Jørgen Juncher; Cui, W.

    2003-01-01

    in the frequency domain. The second-order vertical displacements induced by the membrane forces are calculated by the von Karman plate theory. The results show that the membrane contribution both in terms of the axial stresses and the effect on the bending stresses can be important......The membrane forces are included in the hydroelastic analysis of a floating plate undergoing large vertical deflections in regular monochromatic multidirectional waves. The first-order vertical displacements induced by the linear wave exciting forces are calculated by the mode expansion method...

  14. Closed Axisymmetric Shells as Flat Jacks

    Science.gov (United States)

    Yudin, S. A.; Sigaeva, T. V.

    Buildings during exploitation can be subjected to the external loadings leading to various kinds of heterogeneous strains or tilts. There is engineering technologies of uplift and flattening of multistory buildings by means of steel shells of the closed volume which are named as flat jacks (FJs) [1]. FJ represents two circular close plates which at the outer contour are joined to torus shell. The oil could be introduced into volume by hydraulic station creating a high pressure. As a result the plates diverge and through inserts from thick plywood create powerful force. The construction and working conditions of flat lifting jacks generates a set of problems of the mathematical modeling which are interesting to study. One of the directions is the geometry optimization. In the paper, we analyze variants of the axisymmetric shells modeling FJs. Stress states of shells with different shapes are compared at the initial loading stage.

  15. Stability of dual solutions of mass transfer on a continuous flat plate moving in parallel or reversely to a free stream in the presence of a chemical reaction with second order slip

    Science.gov (United States)

    Najib, Najwa; Bachok, Norfifah; Arifin, Norihan Md.

    2017-04-01

    The present paper investigates the steady viscous flow and mass transfer on a moving plate in parallel or reversely to a free stream in the presence of chemical reaction using a second order slip flow model. The governing partial differential equations are transformed into nonlinear ordinary differential equations by using appropriate similarity transformations, which are then solved numerically using shooting method for different values of selected parameters. We found that dual solutions exist for a certain range of the velocity ratio parameter. By using bvp4c solver in Matlab software, a stability analysis is performed to show that the first solutions are stable and physically relevant, while the second solutions are unstable and not physically relevant. The effects of reaction rate parameter, Schmidt number, first order slip parameter and second order slip parameter on the skin friction coefficient, mass transfer from the surface of the plate, dimensionless velocity and concentration profiles are figured out graphically and discussed. These results reveal that the second order slip flow model is necessary to give better prediction to the flow behavior.

  16. Cold plate

    Energy Technology Data Exchange (ETDEWEB)

    Marroquin, Christopher M.; O' Connell, Kevin M.; Schultz, Mark D.; Tian, Shurong

    2018-02-13

    A cold plate, an electronic assembly including a cold plate, and a method for forming a cold plate are provided. The cold plate includes an interface plate and an opposing plate that form a plenum. The cold plate includes a plurality of active areas arranged for alignment over respective heat generating portions of an electronic assembly, and non-active areas between the active areas. A cooling fluid flows through the plenum. The plenum, at the non-active areas, has a reduced width and/or reduced height relative to the plenum at the active areas. The reduced width and/or height of the plenum, and exterior dimensions of cold plate, at the non-active areas allow the non-active areas to flex to accommodate surface variations of the electronics assembly. The reduced width and/or height non-active areas can be specifically shaped to fit between physical features of the electronics assembly.

  17. Root-Contact/Pressure-Plate Assembly For Hydroponic System

    Science.gov (United States)

    Morris, Carlton E.; Loretan, Philip A.; Bonsi, Conrad K.; Hill, Walter A.

    1994-01-01

    Hydroponic system includes growth channels equipped with rootcontact/pressure-plate assemblies. Pump and associated plumbing circulate nutrient liquid from reservoir, along bottom of growth channels, and back to reservoir. Root-contact/pressure-plate assembly in each growth channel stimulates growth of roots by applying mild contact pressure. Flat plate and plate connectors, together constitute pressure plate, free to move upward to accommodate growth of roots. System used for growing sweetpotatoes and possibly other tuber and root crops.

  18. Flat-port connectors

    KAUST Repository

    Alrashed, Mohammed

    2017-05-26

    Disclosed are various embodiments for connectors used with electronic devices, such as input and/or output ports to connect peripheral equipment or accessories. More specifically, various flat-port are provided that can be used in place of standard connectors including, but not limited to, audio jacks and Universal Serial Bus (USB) ports. The flat-port connectors are an alternate connection design to replace the traditional receptacle port (female-port), making the device more sealed creation more dust and water resistant. It is unique in the way of using the outer surfaces of the device for the electrical connection between the ports. Flat-port design can allow the manufacture of extremely thin devices by eliminating the side ports slots that take a lot of space and contribute to the increase thickness of the device. The flat-port receptacle improves the overall appearance of the device and makes it more resistant to dust and water.

  19. A flat triangular shell element with Loof nodes

    DEFF Research Database (Denmark)

    Poulsen, Peter Noe; Damkilde, Lars

    1996-01-01

    In the formulation of flat shell elements it is difficult to achieve inter-element compatibility between membrane and transverse displacements for non-coplanar elements. Many elements lack proper nodal degrees of freedom to model intersections making the assembly of elements troublesome. A flat...... triangular shell element is established by a combination of a new plate bending element DKTL and the well-known linear membrane strain element LST, and for this element the above-mentioned deficiences are avoided. The plate bending element DKTL is based on Discrete Kirchhoff Theory and Loof nodes. The nodal...

  20. Individual energy savings for individual flats in blocks of flats

    DEFF Research Database (Denmark)

    Nielsen, Anker; Rose, Jørgen

    2014-01-01

    is distributed on the individual flats. Today, most blocks of flats have individual heat meters to save energy and to ensure a fair distribution of the cost. If all flats have the same indoor temperature, the distribution is correct. In practice, the inhabitants of the different flats maintain different indoor......It is well known that similar flats in a block do not have the same energy demand. Part of the explanation for this is the location of the flat in the building, e.g. on the top floor, at the house end or in the middle of the building. It is possible to take this into account when the heating bill...... temperatures. The result is that heat flows between individual flats. This decreases the energy consumption in the flat where the owner maintains a lower temperature. The neighbouring flats will have higher energy consumption. Calculations were performed for Danish blocks of flats from 1920, 1940, 1960...

  1. A New Triangular Flat Shell Element With Drilling Rotations

    DEFF Research Database (Denmark)

    Damkilde, Lars

    2008-01-01

    A new flat triangular shell element has been developed based on a newly developed triangular plate bending element by the author and a new triangular membrane element with drilling degrees of freedom. The advantage of the drilling degree of freedom is that no special precautions have to be made...... in connecting with assembly of elements. Due to the drilling rotations all nodal degrees of freedom have stiffness, and therefore no artificial suppression of degrees of freedom are needed for flat or almost flat parts of the shell structure....

  2. Characteristic of Local Boiling Heat Transfer of Ammonia / Water Binary Mixture on the Plate Type Evaporator

    Science.gov (United States)

    Okamoto, Akio; Arima, Hirofumi; Kim, Jeong-Hun; Akiyama, Hirokuni; Ikegami, Yasuyuki; Monde, Masanori

    Ocean thermal energy conversion (OTEC) and discharged thermal energy conversion (DTEC) are expected to be the next generation energy production systems. Both systems use a plate type evaporator, and ammonia or ammonia/water mixture as a working fluid. It is important to clarify heat transfer characteristic for designing efficient power generation systems. Measurements of local boiling heat transfer coefficients and visualization were performed for ammonia /water mixture (z = 0.9) on a vertical flat plate heat exchanger in a range of mass flux (7.5 - 15 kg/m2s), heat flux (15 - 23 kW/m2), and pressure (0.7 - 0.9 MPa). The result shows that in the case of ammonia /water mixture, the local heat transfer coefficients increase with an increase of vapor quality and mass flux, and decrease with an increase of heat flux, and the influence of the flow pattern on the local heat transfer coefficient is observed.

  3. Solution for Flat Roofs

    Directory of Open Access Journals (Sweden)

    Şt. Vasiliu

    2008-01-01

    Full Text Available Roofs are constructive subassemblies that are located at the top of buildings, which toghether with perimetral walls and some elements of the infrastructure belongs to the subsystem elements that close the building. An important share in the roofing is represented by the flat roofs. Flat roofs must meet the requirements of resistance to mechanical action, thermal insulation, acoustic and waterproof, fire resistance, durability and aesthetics. To meet these requirements is necessary an analysis of the component layers and materials properties that determine the durability of structural assembly.

  4. Structure analysis of low velocity reactive flows on a flat plate: the case of the laminar diffusion flame in a low gravity environment; Analyse de la structure des ecoulements reactifs a faible vitesse sur une plaque plane: cas de la flamme de diffusion laminaire sous un environnement de gravite reduite

    Energy Technology Data Exchange (ETDEWEB)

    Joulain, P.

    2003-09-01

    The combustion of a flat plate in a boundary layer under microgravity conditions, which was first described by Emmons, is studied using a gaseous burner. Magnitude of injection and blowing velocities are chosen to be characteristic of pyrolyzing velocity of solid fuels and of ventilation systems in space stations. These velocities are about 10 cm/s for oxidizer flow and 0.4 cm/s for fuel flow. In this configuration, flame layout results from a coupled interaction between oxidizer flow, fuel flow and thermal expansion. Influences of these parameters are studied by means of flame length and standoff distance measurements using CH* chemiluminescence's and visible emission of the flame. Flow was also studied with Particle Image Velocimetry (PIV). At first with inert flows, with and without injection to identify burner effects on it, and then with a reacting flow in a microgravity environment. Thermal expansion effects have been shown by means of the acceleration of oxidizer flow. Three dimensional effects, which are strongly marked for high injection velocities did not were studied, but three dimensional tools adaptability (wavelength and polarizing coding laser tomography) to parabolic flights particular conditions were investigate. Flame sensitivity to g-jitters was studied using a local modified Richardson number introduced by Torero and g-jitters effect on flame were investigated according to g-jitters frequency and range involved by parabolic flights. (author)

  5. Stress field evolution above the Peruvian flat-slab (Cordillera Blanca, northern Peru)

    Science.gov (United States)

    Margirier, A.; Audin, L.; Robert, X.; Pêcher, A.; Schwartz, S.

    2017-08-01

    In subduction settings, the tectonic regime of the overriding plate is closely related to the geometry of the subducting plate. Flat-slab segments are supposed to increase coupling at the plate interface in the Andes, resulting in an increase and eastward migration of the shortening in the overriding plate. Above the Peruvian flat-slab, a 200 km-long normal fault trend parallel to the range and delimits the western flank of the Cordillera Blanca. In a context of flat subduction, expected to produce shortening, the presence of the Cordillera Blanca normal fault (CBNF) is surprising. We performed a systematic inversion of striated fault planes in the Cordillera Blanca region to better characterize the stress field above the Peruvian flat-slab. It evidences the succession of different tectonic regimes. NE-SW extension is predominant in most of the sites indicating a regional extension. We suggest that the Peruvian flat-slab trigger extension in the Western Cordillera while the shortening migrated eastward. Finally, we propose that flat-slab segments do not increase the coupling at the trench neither the shortening in the overriding plate but only favor shortening migration backward. However, the stress field of the overriding plate arises from the evolution of plate interface properties through time due to bathymetric anomaly migration.

  6. The Role of Subducting Ridges in the Formation of Flat Slabs: Insights from the Peruvian Flat Slab

    Science.gov (United States)

    Knezevic Antonijevic, Sanja; Wagner, Lara; Kumar, Abhash; Beck, Susan; Long, Maureen; Zandt, George; Eakin, Caroline M.

    2015-04-01

    Flattening of the subducting plate is often used to explain various geological features removed far from the subducting margins, including basement-cored uplifts, the cessation of arc volcanism, ignimbrite flare-ups, and the formation of high plateaus and ore deposits [Humphreys et al., 2003; Gutscher et al., 2000; Rosenbaum et al., 2005, Kay and Mpodozis, 2001]. Today, flat slab subduction is observed in central Chile and Peru, representing the modern analogues to the immense paleo-flat slab that subducted beneath the North American continent during the Laramide orogeny (80-55 Ma) [English et al., 2003]. However, how flat slabs form and what controls their inboard and along-strike extent is still poorly understood. To better understand modern and paleo-flat slabs, we focus on the Peruvian flat slab, where the Nazca plate starts to bend at ~90 km depth and travels horizontally for several hundred kilometers beneath the South American plate. Earlier studies propose a correlation between the flat slab and the subducting Nazca Ridge that has been migrating to the south over the past 11 ~Ma [Hampel et al., 2004, Gutscher et al., 2003]. Combining 3D shear wave velocity structure and Rayleigh wave phase anisotropy between ~10° and 18° S, we find that the flat slab has the greatest inboard extent along the track of the subducting Nazca Ridge. North of the ridge track, where the flat slab was initially formed, the flat slab starts to sag, tear and re-initiate steep slab subduction, allowing inflow of warm asthenosphere. Based on our new constraints on the geometry of the subducted plate, we find that the subduction of buoyant oceanic features with overthickened oceanic crust plays a vital role in the formation of flat slabs. We further develop a model of temporal evolution of the Peruvian flab slab that forms as a result of the combined effects of the subducting ridge, trench retreat, and suction forces. Once the buoyant ridge subducts to ~90 km depth, it will fail to

  7. An experimental assessment of resistance reduction and wake modification of a KVLCC model by using outer-layer vertical blades

    Directory of Open Access Journals (Sweden)

    Nam Hyun An

    2014-03-01

    Full Text Available In this study, an experimental investigation has been made of the applicability of outer-layer vertical blades to real ship model. After first devised by Hutchins and Choi (2003, the outer-layer vertical blades demonstrated its effectiveness in reducing total drag of flat plate (Park et al., 2011 with maximum drag reduction of 9.6%. With a view to assessing the effect in the flow around a ship, the arrays of outer-layer vertical blades have been installed onto the side bottom and flat bottom of a 300k KVLCC model. A series of towing tank test has been carried out to investigate resistance (CTM reduction efficiency and improvement of stern wake distribution with varying geometric parameters of the blades array. The installation of vertical blades led to the CTM reduction of 2.15∼2.76% near the service speed. The nominal wake fraction was affected marginally by the blades array and the axial velocity distribution tended to be more uniform by the blades array.

  8. An experimental assessment of resistance reduction and wake modification of a kvlcc model by using outer-layer vertical blades

    Directory of Open Access Journals (Sweden)

    An Nam Hyun

    2014-03-01

    Full Text Available In this study, an experimental investigation has been made of the applicability of outer-layer vertical blades to real ship model. After first devised by Hutchins and Choi (2003, the outer-layer vertical blades demonstrated its effectiveness in reducing total drag of flat plate (Park et al., 2011 with maximum drag reduction of 9.6%. With a view to assessing the effect in the flow around a ship, the arrays of outer-layer vertical blades have been installed onto the side bottom and flat bottom of a 300k KVLCC model. A series of towing tank test has been carried out to investigate resistance (CTM reduction efficiency and improvement of stern wake distribution with varying geometric parameters of the blades array. The installation of vertical blades led to the CTM reduction of 2.15~2.76% near the service speed. The nominal wake fraction was affected marginally by the blades array and the axial velocity distribution tended to be more uniform by the blades array.

  9. Piecewise flat gravitational waves

    NARCIS (Netherlands)

    van de Meent, M.|info:eu-repo/dai/nl/314007067

    2011-01-01

    We examine the continuum limit of the piecewise flat locally finite gravity model introduced by ’t Hooft. In the linear weak field limit, we find the energy–momentum tensor and metric perturbation of an arbitrary configuration of defects. The energy–momentum turns out to be restricted to satisfy

  10. Towards a flat 45%-efficient concentrator module

    Energy Technology Data Exchange (ETDEWEB)

    Mohedano, Rubén, E-mail: rmohedano@lpi-europe.com; Hernandez, Maikel; Vilaplana, Juan; Chaves, Julio; Sorgato, S.; Falicoff, Waqidi [LPI, Altadena, CA, USA and Madrid (Spain); Miñano, Juan C.; Benitez, Pablo [LPI, Altadena, CA, USA and Madrid (Spain); Universidad Politécnica de Madrid (UPM), Campus de Montegancedo, Madrid (Spain)

    2015-09-28

    The so-called CCS{sup 4}FK is an ultra-flat photovoltaic system of high concentration and high efficiency, with potential to convert, ideally, the equivalent of a 45% of direct solar radiation into electricity by optimizing the usage of sun spectrum and by collecting part of the diffuse radiation, as a flat plate does. LPI has recently finished a design based on this concept and is now developing a prototype based on this technology, thanks to the support of FUNDACION REPSOL-Fondo de Emprendedores, which promotes entrepreneur projects in different areas linked to energy. This works shows some details of the actual design and preliminary potential performance expected, according to accurate spectral simulations.

  11. Towards a flat 45%-efficient concentrator module

    Science.gov (United States)

    Mohedano, Rubén; Hernandez, Maikel; Vilaplana, Juan; Chaves, Julio; Miñano, Juan C.; Benitez, Pablo; Sorgato, S.; Falicoff, Waqidi

    2015-09-01

    The so-called CCS4FK is an ultra-flat photovoltaic system of high concentration and high efficiency, with potential to convert, ideally, the equivalent of a 45% of direct solar radiation into electricity by optimizing the usage of sun spectrum and by collecting part of the diffuse radiation, as a flat plate does. LPI has recently finished a design based on this concept and is now developing a prototype based on this technology, thanks to the support of FUNDACION REPSOL-Fondo de Emprendedores, which promotes entrepreneur projects in different areas linked to energy. This works shows some details of the actual design and preliminary potential performance expected, according to accurate spectral simulations.

  12. Cryogenic flat-panel gas-gap heat switch

    NARCIS (Netherlands)

    Vanapalli, Srinivas; Keijzer, R.; Buitelaar, P.; ter Brake, Hermanus J.M.

    2016-01-01

    A compact additive manufactured flat-panel gas-gap heat switch operating at cryogenic temperature is reported in this paper. A guarded-hot-plate apparatus has been developed to measure the thermal conductance of the heat switch with the heat sink temperature in the range of 100–180 K. The apparatus

  13. High-order-harmonic generation in gas with a flat-top laser beam

    Energy Technology Data Exchange (ETDEWEB)

    Boutu, W.; Auguste, T.; Binazon, L.; Gobert, O.; Carre, B. [Service des Photons, Atomes et Molecules, CEA-Saclay, FR-91191 Gif-sur-Yvette Cedex (France); Boyko, O.; Valentin, C. [Laboratoire d' Optique Appliquee, UMR 7639 ENSTA/CNRS/Ecole Polytechnique, FR-91761 Palaiseau (France); Sola, I.; Constant, E.; Mevel, E. [Universite de Bordeaux, CEA, CNRS UMR 5107, CELIA (Centre Lasers Intenses et Applications), FR-33400 Talence (France); Balcou, Ph. [Laboratoire d' Optique Appliquee, UMR 7639 ENSTA/CNRS/Ecole Polytechnique, FR-91761 Palaiseau (France); Universite de Bordeaux, CEA, CNRS UMR 5107, CELIA (Centre Lasers Intenses et Applications), FR-33400 Talence (France); Merdji, H. [Service des Photons, Atomes et Molecules, CEA-Saclay, FR-91191 Gif-sur-Yvette Cedex (France); PULSE Institute for Ultrafast Energy Science, Stanford Linear Accelerator Center, Stanford University, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)

    2011-12-15

    We present experimental and numerical results on high-order-harmonic generation with a flat-top laser beam. We show that a simple binary tunable phase plate, made of two concentric glass plates, can produce a flat-top profile at the focus of a Gaussian infrared beam. Both experiments and numerical calculations show that there is a scaling law between the harmonic generation efficiency and the increase of the generation volume.

  14. Classifications, sedimentary features and facies associations of tidal flats

    Directory of Open Access Journals (Sweden)

    Fan Daidu

    2013-01-01

    Full Text Available Significant progress has been achieved in the research of tide-dominated environments in the past two decades. These studies highlight both the importance and diversity of tidal flats in modern coastal environments. Based on their developing settings, tidal flats are subdivided into nine types, which are in turn grouped into sheltered or exposed spectrums according to the magnitude of exposure to waves. The ternary coastal classification model is revised with an embedded triangle to highlight non-open coast tidal flats as major second-order morphological elements to the first-order coastal environments including deltas, estuaries and lagoons. A new continuous spectrum of open coast depositional settings is proposed from muddy tidal flats of tide dominance with wave influence, through sandy tidal flats of mixed energy (tide-dominated, and tidal beaches of mixed energy (wave-dominated, to beaches of wave-dominance with tide influence. It is worth noting that no open coast setting is absolutely exempt from wave or tide influence. Three diagnostic criteria for the intertidal-flat deposits are proposed. Upon an upward-fining succession, (1 regular changes vertically from flaser bedding, through wavy bedding and to lenticular bedding are diagnostic of most of intertidal flats; (2 cyclical tidal rhythmites point to sheltered intertidal flats typically at the inner part of macrotidal estuaries; (3 rhythmic alternations of storm and tidal deposition are diagnostic of exposed intertidal flats, especially the open coast types. Intertidal-flat deposits are generally topped by saltmarsh deposits, but underlain by different subtidal successions, like thick subtidal channel-fills, sand-bar complexes (sheltered coastal settings, and upwards coarsening successions of subtidal flats or thick subtidal sand ridge/bar complexes (exposed coastal environments.

  15. Plate tectonics

    Digital Repository Service at National Institute of Oceanography (India)

    Chaubey, A.K.

    Content-Type text/plain; charset=UTF-8 209 Plate Tectonics A. K. Chaubey National Institute of Oceanography, Dona Paula, Goa-403 004. chaubey@nio.org Introduction The theory of continental drift, which paved the way for discovery... of plate tectonics, was put forward by Alfred Lother Wegener - a meteorologist from Germany - in 1912. The theory states that continents are not fixed, but have been slowly wandering during the course of Earth’s geological history. Although Wegener...

  16. Locally available materials for use as flat plate solar absorber ...

    African Journals Online (AJOL)

    Global Journal of Pure and Applied Sciences. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 7, No 3 (2001) >. Log in or Register to get access to full text downloads.

  17. Full Scale Measurements of Wave Impact on a Flat Plate

    Science.gov (United States)

    2013-05-01

    University of California San Diego. The pier sits upon an array of 0.67 m diameter steel reinforced concrete pilings, supports a concrete deck 10.25 m...contained within each panel close to the sensors to reduce noise. Each module has a multi-pin underwater connector on the back and waterproof cables for

  18. Optimization of flat plate drying of carrot pomace (abstract)

    Science.gov (United States)

    Carrot (Daucus carota var. sativus) pomace is a co-product of the carrot juice and cut-carrot industry; it has high nutritional value but is currently underutilized. Drum drying is one method that could be used to dry and stabilize carrot pomace. However, optimum conditions for the dryer surface tem...

  19. dynamic modeling of natural convection solar energy flat plate ...

    African Journals Online (AJOL)

    NIJOTECH

    exposed to solar radiation, and was not given further black painting. The glazing material was clear window glass, 0.004m thick, 1.225m long, 0.95m wide, with 0.94m of the width exposed to solar radiation. The insulation material was sawdust obtained from a sawmill at Nsukka, Nigeria. The dimensions of the collector and ...

  20. Thermal characterization of flat-plate photovoltaic arrays

    Science.gov (United States)

    Fuentes, M. K.

    The net effect of an array's operating cell temperature on energy output can be characterized by a single effective cell temperature (ECT). ECT is that temperature at which an array would operate were it to operate at a constant cell temperature and produce the same energy as it would in the natural environment. Since an array effectively produces all of its energy at ECT, an operating efficiency at ECT is also the overall efficiency of the array. A methodology for estimating ECT from the Nominal Operating Cell Temperature (NOCT)is presented. Also presented is new thermal model. The model has been incorporated into the photovoltaic (PV) performance model, PVFORM, and has been proven to be accurate to within 5 C.

  1. Flat plate collector performance determined experimentally with a solar simulator

    Science.gov (United States)

    Vernon, R. W.; Simon, F. F.

    1974-01-01

    The NASA is constructing a new office building at Langley Research Center that will utilize solar energy for heating and cooling. A collector technology program being conducted at Lewis will provide the basis for selecting collectors for use at Langley. The technology program includes testing collectors in an indoor facility under simulated solar radiation. Tests have been conducted on five collectors to date and performance data are presented herein.

  2. Cost effective flat plate photovoltaic modules using light trapping

    Science.gov (United States)

    Bain, C. N.; Gordon, B. A.; Knasel, T. M.; Malinowski, R. L.

    1981-01-01

    Work in optical trapping in 'thick films' is described to form a design guide for photovoltaic engineers. A thick optical film can trap light by diffusive reflection and total internal reflection. Light can be propagated reasonably long distances compared with layer thicknesses by this technique. This makes it possible to conduct light from inter-cell and intra-cell areas now not used in photovoltaic modules onto active cell areas.

  3. On-Line Flatness Measurement in the Steelmaking Industry

    Directory of Open Access Journals (Sweden)

    Rubén Usamentiaga

    2013-08-01

    Full Text Available Shape is a key characteristic to determine the quality of outgoing flat-rolled products in the steel industry. It is greatly influenced by flatness, a feature to describe how the surface of a rolled product approaches a plane. Flatness is of the utmost importance in steelmaking, since it is used by most downstream processes and customers for the acceptance or rejection of rolled products. Flatness sensors compute flatness measurements based on comparing the length of several longitudinal fibers of the surface of the product under inspection. Two main different approaches are commonly used. On the one hand, most mechanical sensors measure the tensile stress across the width of the rolled product, while manufacturing and estimating the fiber lengths from this stress. On the other hand, optical sensors measure the length of the fibers by means of light patterns projected onto the product surface. In this paper, we review the techniques and the main sensors used in the steelmaking industry to measure and quantify flatness defects in steel plates, sheets and strips. Most of these techniques and sensors can be used in other industries involving rolling mills or continuous production lines, such as aluminum, copper and paper, to name a few. Encompassed in the special issue, State-of-the-Art Sensors Technology in Spain 2013, this paper also reviews the most important flatness sensors designed and developed for the steelmaking industry in Spain.

  4. Asymptotically flat multiblack lenses

    Science.gov (United States)

    Tomizawa, Shinya; Okuda, Taika

    2017-03-01

    We present an asymptotically flat and stationary multiblack lens solution with biaxisymmetry of U (1 )×U (1 ) as a supersymmetric solution in the five-dimensional minimal ungauged supergravity. We show that the spatial cross section of each degenerate Killing horizon admits different lens space topologies of L (n ,1 )=S3/Zn as well as a sphere S3. Moreover, we show that, in contrast to the higher-dimensional Majumdar-Papapetrou multiblack hole and multi-Breckenridge-Myers-Peet-Vafa (BMPV) black hole spacetime, the metric is smooth on each horizon even if the horizon topology is spherical.

  5. DIURNAL VERTICAL MIGRATIONS OF MEIOFAUNA IN AN ...

    African Journals Online (AJOL)

    Diurnal vertical migrations of meiofauna were observed in an estuarine sand flat and these were related primarily to desiccation and temperature. The migrations. which occurred in the top 10 cm of the sediment. had a mean range of 5 cm and were most strongly exhibited by the interstitial flatworms. polychaetes and ...

  6. Near-Surface Boundary Layer Turbulence Along a Horizontally-Moving, Surface-Piercing Vertical Wall

    CERN Document Server

    Washuta, Nathan; Duncan, James H

    2016-01-01

    The complex interaction between turbulence and the free surface in boundary layer shear flow created by a vertical surface-piercing wall is considered. A laboratory-scale device was built that utilizes a surface-piercing stainless steel belt that travels in a loop around two vertical rollers, with one length of the belt between the rollers acting as a horizontally-moving flat wall. The belt is accelerated suddenly from rest until reaching constant speed in order to create a temporally-evolving boundary layer analogous to the spatially-evolving boundary layer that would exist along a surface-piercing towed flat plate. Surface profiles are measured with a cinematic laser-induced fluorescence system and sub-surface velocity fields are recorded using a high-speed planar particle image velocimetry system. It is found that the belt initially travels through the water without creating any significant waves, before the free surface bursts with activity close to the belt surface. These free surface ripples travel away...

  7. Development of Surfaces Optically Suitable for Flat Solar Panels

    Science.gov (United States)

    Desmet, D.; Jason, A.

    1978-01-01

    Three areas of research in the development of flat solar panels are described. (1) A reflectometer which can separately evaluate the spectral and diffuse reflectivities of surfaces was developed. The reflectometer has a phase locked detection system. (2) A coating composed of strongly bound copper oxide that is formed by an etching process performed on an aluminum alloy with high copper content was also developed. Because of this one step fabrication process, fabrication costs are expected to be small. (3) A literature search was conducted and conclusions on the required optical properties of flat plate solar collectors are presented.

  8. Numerical simulations on a twin-plate wake

    DEFF Research Database (Denmark)

    Fernández-Gámiz, U.; Velte, Clara Marika; Egusquiza, E.

    2013-01-01

    In this work, a detailed numerical analysis of two dimensional mean velocity profiles downstream of two parallel flat plates was carried out at a Reynolds number of 3.2x104 (based on the plate length and free stream velocity) using Reynolds Averaged Navier-Stokes (RANS) and have been compared wit...

  9. IS THE WORLD FLAT?

    Directory of Open Access Journals (Sweden)

    Cristian Încalţărău

    2010-06-01

    Full Text Available Globalization became more and more prominent during the last decades. There is no way to argue that globalization led to more interconnected economies, facilitating the communication and the collaboration around the world. But where is this going? Doesglobalization mean uniformity or diversity? As the world begins to resemble more, the people are trying to distinguish between them more, which can exacerbate nationalistic feeling. Friedman argues that globalization made the world smaller and flatter, allowing all countries to take chance of the available opportunities equally. But is this really true? Although politic and cultural factors can stand in front of a really flat world, what is the key for Chinese and Indian success and which are theirs perspectives?

  10. Design of Corrugated Plates for Optimal Fundamental Frequency

    Directory of Open Access Journals (Sweden)

    Nabeel Alshabatat

    2016-01-01

    Full Text Available This paper investigates shifting the fundamental frequency of plate structures by corrugation. Creating corrugations significantly improves the flexural rigidities of plate and hence increases its natural frequencies. Two types of corrugations are investigated: sinusoidal and trapezoidal corrugations. The finite element method (FEM is used to model the corrugated plates and extract the natural frequencies and mode shapes. The effects of corrugation geometrical parameters on simply supported plate fundamental frequency are studied. To reduce the computation time, the corrugated plates are modeled as orthotropic flat plates with equivalent rigidities. To demonstrate the validity of modeling the corrugated plates as orthotropic flat plates in studying the free vibration characteristics, a comparison between the results of finite element model and equivalent orthotropic models is made. A correspondence between the results of orthotropic models and the FE models is observed. The optimal designs of sinusoidal and trapezoidal corrugated plates are obtained based on a genetic algorithm. The optimization results show that plate corrugations can efficiently maximize plate fundamental frequency. It is found that the trapezoidal corrugation can more efficiently enhance the fundamental frequency of simply supported plate than the sinusoidal corrugation.

  11. Transient motion of a circular plate after an impact.

    Science.gov (United States)

    Moore, Thomas R; Zietlow, Daniel W; Gorman, Christopher W; Griffin, Donald C; Ballance, Connor P; Parker, David J

    2009-02-01

    The transient response of a flat circular plate to a sudden impact has been studied experimentally and theoretically. High-speed electronic speckle pattern interferometry reveals the presence of pulses that travel around the edge of the plate ahead of the bending motion initiated by the strike. It is found that the transient motion of the plate is well described by Kirchhoff thin-plate theory over a time approximately equal to the time required for the initial impulse to circumvent the plate; however, a more sophisticated model is required to describe the motion after this time has elapsed.

  12. Exact piecewise flat gravitational waves

    NARCIS (Netherlands)

    van de Meent, M.|info:eu-repo/dai/nl/314007067

    2011-01-01

    We generalize our previous linear result (van de Meent 2011 Class. Quantum Grav 28 075005) in obtaining gravitational waves from our piecewise flat model for gravity in 3+1 dimensions to exact piecewise flat configurations describing exact planar gravitational waves. We show explicitly how to

  13. Line bundles and flat connections

    Indian Academy of Sciences (India)

    Calabi–Yau threefold; torsion; cocompact lattice; unitary representation. 2000 Mathematics Subject Classification. 81T30, 14D21, 53C07. 1. Stable bundles and unitary flat connections. 1.1 Admitting flat connections. Let X be a compact connected complex manifold of complex dimension δ. Let ω be the. (1, 1)-form on X ...

  14. Indonesian Landforms and Plate Tectonics

    Directory of Open Access Journals (Sweden)

    Herman Th. Verstappen

    2014-06-01

    Full Text Available DOI: 10.17014/ijog.v5i3.103The horizontal configuration and vertical dimension of the landforms occurring in the tectonically unstable parts of Indonesia were resulted in the first place from plate tectonics. Most of them date from the Quaternary and endogenous forces are ongoing. Three major plates – the northward moving Indo-Australian Plate, the south-eastward moving SE-Asian Plate and the westward moving Pacific Plate - meet at a plate triple-junction situated in the south of New Guinea’s Bird’s Head. The narrow North-Moluccan plate is interposed between the Asia and Pacific. It tapers out northward in the Philippine Mobile Belt and is gradually disappearing. The greatest relief amplitudes occur near the plate boundaries: deep ocean trenches are associated with subduction zones and mountain ranges with collision belts. The landforms of the more stable areas of the plates date back to a more remote past and, where emerged, have a more subdued relief that is in the first place related to the resistance of the rocks to humid tropical weathering Rising mountain ranges and emerging island arcs are subjected to rapid humid-tropical river erosions and mass movements. The erosion products accumulate in adjacent sedimentary basins where their increasing weight causes subsidence by gravity and isostatic compensations. Living and raised coral reefs, volcanoes, and fault scarps are important geomorphic indicators of active plate tectonics. Compartmental faults may strongly affect island arcs stretching perpendicular to the plate movement. This is the case on Java. Transcurrent faults and related pull-apart basins are a leading factor where plates meet at an angle, such as on Sumatra. The most complicated situation exists near the triple-junction and in the Moluccas. Modern research methods, such as GPS measurements of plate movements and absolute dating of volcanic outbursts and raised coral reefs are important tools. The mega-landforms resulting

  15. Create Your Plate

    Medline Plus

    Full Text Available ... A A A Listen En Español Create Your Plate Create Your Plate is a simple and effective ... and that your options are endless. Create Your Plate! Click on the plate sections below to add ...

  16. 40 CFR 230.42 - Mud flats.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Mud flats. 230.42 Section 230.42... Aquatic Sites § 230.42 Mud flats. (a) Mud flats are broad flat areas along the sea coast and in coastal rivers to the head of tidal influence and in inland lakes, ponds, and riverine systems. When mud flats...

  17. Segmental and Kinetic Contributions in Vertical Jumps Performed with and without an Arm Swing

    Science.gov (United States)

    Feltner, Michael E.; Bishop, Elijah J.; Perez, Cassandra M.

    2004-01-01

    To determine the contributions of the motions of the body segments to the vertical ground reaction force ([F.sub.z]), the joint torques produced by the leg muscles, and the time course of vertical velocity generation during a vertical jump, 15 men were videotaped performing countermovement vertical jumps from a force plate with and without an arm…

  18. Time Resolved PIV Investigation on the Skin Friction Reduction Mechanism of Outer-Layer Vertical Blades Array

    Directory of Open Access Journals (Sweden)

    Seong Hyeon Park

    2015-02-01

    Full Text Available The drag reducing efficiency of the outer-layer vertical blades, which were first devised by Hutchins (2003, have been demonstrated by the recent towing tank measurements. From the drag measurement of flat plate with various vertical blades arrays by Park et al. (2011, a maximum 9.6% of reduction of total drag was achieved. The scale of blade geometry is found to be weakly correlated with outer variable of boundary layer. The drag reduction of 2.8% has been also confirmed by the model ship test by An et al. (2014. With a view to enabling the identification of drag reduction mechanism of the outer-layer vertical blades, detailed flow field measurements have been performed using 2D time resolved PIV in this study. It is found that the skin friction reduction effect is varied according to the spanwise position, with 2.73% and 7.95% drag reduction in the blade plane and the blade-in-between plane, respectively. The influence of vertical blades array upon the characteristics of the turbulent coherent structures was analyzed by POD method. It is observed that the vortical structures are cut and deformed by blades array and the skin frictional reduction is closely associated with the subsequent evolution of turbulent structures.

  19. Free locomotion of a flexible plate near the ground

    Science.gov (United States)

    Zhang, Chengyao; Huang, Haibo; Lu, Xi-Yun

    2017-04-01

    The free locomotion of a two-dimensional flapping flexible plate near the flat ground is studied by the lattice Boltzmann method for fluid flow and a finite-element method for the plate motion. The fluid flow and plate deformation are coupled through the immersed boundary scheme. When the leading edge of the plate is forced to oscillate sinusoidally near the ground, the plate may move freely in the horizontal direction due to the fluid-structure interaction. The mechanisms underlying the ground effect are elucidated. Besides a moderate rigidity, it is found that an appropriate density ratio between the plate and surrounding fluid (M) can improve the propulsive efficiency of the plate. When M is relatively small, the lateral force is enhanced, and the input work is increased when the plate is near the ground; when M is large, the deformation of the plate is inhibited and the input work is decreased when the plate is close to the ground. Usually the closer the plate flapping is to the wall, the more efficient the propulsion is, provided that the tail of the plate would not touch the wall. On the other hand, when the plate is close enough (within a critical lowest distance), the efficiency reaches a plateau with the highest efficiency. The vortices pattern and pressure field are also analyzed to explore the mechanism. This study may shed some light on mechanism for self-propulsion of a flexible plate near the ground.

  20. Investigation of the flow-field of two parallel round jets impinging normal to a flat surface

    Science.gov (United States)

    Myers, Leighton M.

    The flow-field features of dual jet impingement were investigated through sub-scale model experiments. The experiments were designed to simulate the environment of a Short Takeoff, and Vertical Landing, STOVL, aircraft performing a hover over the ground, at different heights. Two different dual impinging jet models were designed, fabricated, and tested. The Generation 1 Model consisted of two stainless-steel nozzles, in a tandem configuration, each with an exit diameter of approximately 12.7 mm. The front convergent nozzle was operated at the sonic Mach number of 1.0, while the rear C-D nozzle was generally operated supersonically. The nozzles were embedded in a rectangular flat plate, referred to as the lift plate, which represents a generic lifting surface. The lift plate was instrumented with 36 surface pressure taps, which were used to examine the flow entrainment and recirculation patterns caused by varying the stand-off distance from the nozzle exits to a flat ground surface. The stand-off distance was adjusted with a sliding rail frame that the ground plane was mounted to. Typical dimensionless stand-off distances (ground plane separation) were H/DR = 2 to 24. A series of measurements were performed with the Generation 1 model, in the Penn State High Speed Jet Aeroacoustics Laboratory, to characterize the basic flow phenomena associated with dual jet impingement. The regions of interest in the flow-field included the vertical jet plume(s), near impingement/turning region, and wall jet outwash. Other aspects of interest included the loss of lift (suckdown) that occurs as the ground plane separation distance becomes small, and azimuthal variation of the acoustic noise radiation. Various experimental methods and techniques were used to characterize the flow-field, including flow-visualization, pressure rake surveys, surface mounted pressure taps, laser Doppler velocimetry, and acoustic microphone arrays. A second dual impinging jet scale model, Generation 2

  1. Flat Head Syndrome (Positional Plagiocephaly)

    Science.gov (United States)

    ... often during the day (infant car seats, carriers, strollers, swings, and bouncy seats) also adds to this ... a flat surface (such as in car seats, strollers, swings, bouncy seats, and play yards). For instance, ...

  2. Improvement of rolling 6 mm thin plates in plate rolling mill PT. Krakatau Posco

    Science.gov (United States)

    Pujiyanto, Hamdani

    2017-01-01

    A 6-mm thin plate is difficult to produce especially if the product requires wide size and high strength. Flatness is the main quality issue in rolling 6-mm plate using a 4-high reversing mill which use ±1100-mm work roll. Thus some methods are applied to overcome such issue in order to comply to customer quality requirement. Pre-rolling, rolling, and post-rolling conditions have to be considered comprehensively. Roll unit management will be the key factor before rolling condition. The roll unit itself has a significant impact on work roll crown wearness in relation with work roll intial crown and thermal crown. Work roll crown along with the modification of hydraulic gap control (HGC) could directly alter the flatness of the plate.

  3. Electromagnetic NDT to characterize usage properties of flat steel products - Part 3

    Energy Technology Data Exchange (ETDEWEB)

    Altpeter, I.; Dobmann, G.; Szielasko, K., E-mail: iab.altlau@t-online.de, E-mail: gerd.dobmann@t-online.de, E-mail: klaus.szielasko@izfp.fraunhofer.de [Fraunhofer Inst. - IZFP, Saarbruecken (Germany)

    2015-11-15

    The Fraunhofer Institute for Nondestructive Testing (IZFP) in Saarbruecken, Germany, started its activities in materials characterization of flat steel products in the eighties of the last century in the basic program of the European Community of Coal and Steel (ECCS). Throughout the years, continuous research and development were performed. The objective of the work, presented within this three-part series of reports, is to discuss the history of an innovation that began in 1988 with R&D in the area of texture characterization in steel sheets produced for car-body manufacturing (Part 1). In the following years the activities were to automate online property determination in terms of yield strength, tensile strength, planar- and vertical-anisotropy factors. Again, steel sheets were the focus of the developments and first NDT systems came into industrial application. Parallel research was performed to characterize the mechanical properties and hardness on heavy steel plates, mainly produced for pipeline manufacturing and offshore applications (Part 2). The final report in the series (Part 3) discusses steel sheet characterization and presents the successful development of a combination transducer that combines ultrasonics with electromagnetic NDT. (author)

  4. Create Your Plate

    Medline Plus

    Full Text Available ... Pacific Islanders American Indian/Alaska Native Programs Older Adults Family Link Diabetes EXPO Upcoming Diabetes EXPOs EXPO ... Plate! Click on the plate sections below to add your food choices. Reset Plate Share Create Your ...

  5. Growth Plate Fractures

    Science.gov (United States)

    .org Growth Plate Fractures Page ( 1 ) The bones of children and adults share many of the same risks for ... also subject to a unique injury called a growth plate fracture. Growth plates are areas of cartilage ...

  6. Create Your Plate

    Medline Plus

    Full Text Available ... Plate! Click on the plate sections below to add your food choices. Reset Plate Share Create Your ... your protein. See this list of protein foods . Add a serving of fruit , a serving of dairy ...

  7. Create Your Plate

    Medline Plus

    Full Text Available ... Plate Create Your Plate is a simple and effective way to manage your blood glucose levels and ... Steps to Create Your Plate It's simple and effective for both managing diabetes and losing weight. Creating ...

  8. Create Your Plate

    Medline Plus

    Full Text Available ... that your options are endless. Create Your Plate! Click on the plate sections below to add your ... down the middle of the plate. Then on one side, cut it again so you will have ...

  9. Viscous dissipation effects on heat transfer in flow past a continuous moving plate

    Digital Repository Service at National Institute of Oceanography (India)

    Soundalgekar, V.M.; Murty, T.V.R.

    The study of thermal boundary layer on taking into account the viscous dissipative heat, on a continuously moving semi-infinite flat plate is presented here.Similarity solutions are derived and the resulting equations are integrated numerically...

  10. Pyrolysis and Boundary Layer Combustion of a Non-Charring Solid Plate Under Forced Flow

    National Research Council Canada - National Science Library

    Ananth, Ramagopal

    2003-01-01

    Solutions of Navier-Stokes (NS) equations were obtained for burning rate Nu and temperature distributions for a flat PMMA plate using an iterative method to impose steady-state, pyrolysis kinetics at the surface...

  11. Flat structure cooled detector assembly

    Science.gov (United States)

    Reeb, Nathalie; Coutures, Bernard; Gerin, Nicolas; Reale, S.; Guille, B.

    1994-07-01

    Long wavelength IR detectors need to be cooled at cryogenic temperature to achieve high performances. This specific need makes it difficult to integrate the detector because of high cost of dewar and cooling device designed to fulfill severe vibration conditions. A new era for IR detection could begin with flat structures allowing intrinsic vibration resistance for detectors to be plugged on electronics board. Sofradir has carried out a study about feasibility of detector dewar assembly including a flat Joule-Thomson cooler with porous heat exchanger in cooperation with Air Liquide. The aim of this paper is to put forward the interest of such a product. The very good results achieved demonstrate a promising future for such flat structure detector assembly.

  12. Fluctuations along supersymmetric flat directions during Inflation

    OpenAIRE

    Enqvist, Kari; Figueroa, Daniel G.; Rigopoulos, Gerasimos

    2011-01-01

    We consider a set of scalar fields, consisting of a single flat direction and one or several non-flat directions. We take our cue from the MSSM, considering separately D-flat and F-flat directions, but our results apply to any supersymmetric scenario containing flat directions. We study the field fluctuations during pure de Sitter Inflation, following the evolution of the infrared modes by numerically solving the appropriate Langevin equations. We demonstrate that for the Standard Model U(1),...

  13. Sigmoid plate dehiscence: Congenital or acquired condition?

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhaohui, E-mail: lzhtrhos@163.com [Capital Medical University, Beijing Tongren Hospital, No 1 Dong Jiao Min Street, Dongcheng District, Beijing 100730 (China); Li, Jing, E-mail: lijingxbh@yahoo.com.cn [Capital Medical University, Beijing Tongren Hospital, No 1 Dong Jiao Min Street, Dongcheng District, Beijing 100730 (China); Zhao, Pengfei, E-mail: zhaopengf05@163.com [Capital Medical University, Beijing Friendship Hospital, No 95 Yongan Road, Xicheng District, Beijing 100050 (China); Lv, Han, E-mail: chrislvhan@126.com [Capital Medical University, Beijing Friendship Hospital, No 95 Yongan Road, Xicheng District, Beijing 100050 (China); Dong, Cheng, E-mail: derc007@sina.com [Capital Medical University, Beijing Friendship Hospital, No 95 Yongan Road, Xicheng District, Beijing 100050 (China); Liu, Wenjuan, E-mail: wenjuanliu@163.com [Jining No. 1 People' s Hospital, No. 6 Health Street, Jining 272100 (China); Wang, Zhenchang, E-mail: cjr.wzhch@vip.163.com [Capital Medical University, Beijing Friendship Hospital, No 95 Yongan Road, Xicheng District, Beijing 100050 (China)

    2015-05-15

    Highlights: • CT with multiplanar reformations can accurately display the sigmoid platet dehiscence. • The prevalence of sigmoid plate dehiscence was no significant difference among different age groups. • The size of sigmoid plate bony defects were not statistically different among different age groups. • The sigmoid plate dehiscence is more commonly a congenital than an acquired condition. - Abstract: Background and purpose: The imaging features of sigmoid plate dehiscence-induced pulsatile tinnitus have been presented. The origin of the sigmoid plate dehiscence, however, remains unclear. Our aim was to assess the prevalence and extent of sigmoid plate dehiscence on computed tomography (CT) images in multiple age groups to determine whether this condition is more likely to be congenital or acquired. Materials and methods: We retrospectively reviewed contrast-enhanced CT images of sigmoid plates of temporal bones in 504 patients. Each temporal bone was characterized as normal or dehiscent. Patients were then subcategorized into four age groups, and the prevalence and extent of dehiscent sigmoid plates in each group were calculated and compared. Results: Overall, 80 patients had sigmoid plate dehiscence, nine of whom had it bilaterally. In successively older age groups, the prevalences of sigmoid plate dehiscence were 18.9%, 20.1%, 14.5%, and 12.7%, respectively. Respective average anteroposterior bony defect diameters were 3.7 ± 1.7, 3.0 ± 1.3, 3.1 ± 1.5, and 3.0 ± 1.1 mm. Respective average vertical bony defect diameters were 3.6 ± 2.3, 2.6 ± 1.2, 3.2 ± 1.5, and 3.0 ± 1.7 mm. The prevalence and extent of sigmoid plate dehiscence were not statistically different among the four age groups. Conclusions: The similar radiologic prevalence and extent of dehiscent sigmoid plates among the age groups suggest that the dehiscence is more commonly a congenital than an acquired condition.

  14. The Fallacies of Flatness: Thomas Friedman's "The World Is Flat"

    Science.gov (United States)

    Abowitz, Kathleen Knight; Roberts, Jay

    2007-01-01

    Thomas Friedman's best-selling "The World is Flat" has exerted much influence in the west by providing both an accessible analysis of globalization and its economic and social effects, and a powerful cultural metaphor for globalization. In this review, we more closely examine Friedman's notion of the social contract, the moral center of his…

  15. Characteristic of local boiling heat transfer of ammonia and ammonia / water binary mixture on the plate type evaporator

    Science.gov (United States)

    Okamoto, Akio; Arima, Hirofumi; Ikegami, Yasuyuki

    2011-08-01

    Power generation using small temperature difference such as ocean thermal energy conversion (OTEC) and discharged thermal energy conversion (DTEC) is expected to be the countermeasures against global warming problem. As ammonia and ammonia/water are used in evaporators for OTEC and DTEC as working fluids, the research of their local boiling heat transfer is important for improvement of the power generation efficiency. Measurements of local boiling heat transfer coefficients were performed for ammonia /water mixture ( z = 0.9-1) on a vertical flat plate heat exchanger in a range of mass flux (7.5-15 kg/m2 s), heat flux (15-23 kW/m2), and pressure (0.7-0.9 MPa). The result shows that in the case of ammonia /water mixture, the local heat transfer coefficients increase with an increase of mass flux and composition of ammonia, and decrease with an increase of heat flux.

  16. Estimate of Joule Heating in a Flat Dechirper

    Energy Technology Data Exchange (ETDEWEB)

    Bane, Karl [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stupakov, Gennady [SLAC National Accelerator Lab., Menlo Park, CA (United States); Gjonaj, Erion [Technical Univ. of Darmstadt (Germany)

    2017-02-10

    We have performed Joule power loss calculations for a flat dechirper. We have considered the configurations of the beam on-axis between the two plates—for chirp control—and for the beam especially close to one plate—for use as a fast kicker. Our calculations use a surface impedance approach, one that is valid when corrugation parameters are small compared to aperture (the perturbative parameter regime). In our model we ignore effects of field reflections at the sides of the dechirper plates, and thus expect the results to underestimate the Joule losses. The analytical results were also tested by numerical, time-domain simulations. We find that most of the wake power lost by the beam is radiated out to the sides of the plates. For the case of the beam passing by a single plate, we derive an analytical expression for the broad-band impedance, and—in Appendix B—numerically confirm recently developed, analytical formulas for the short-range wakes. While our theory can be applied to the LCLS-II dechirper with large gaps, for the nominal apertures we are not in the perturbative regime and the reflection contribution to Joule losses is not negligible. With input from computer simulations, we estimate the Joule power loss (assuming bunch charge of 300 pC, repetition rate of 100 kHz) is 21 W/m for the case of two plates, and 24 W/m for the case of a single plate.

  17. Miniature Flat Plasma Spectrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This phase I SBIR project will develop a micromachined charged particle energy collimator plate to be used as a principle component in a micromachined plasma...

  18. Boundaries of flat compact surfaces

    DEFF Research Database (Denmark)

    Røgen, Peter

    1999-01-01

    type. The number of $3$-singular points (points of zero curvature or if not then of zero torsion) on the boundary of a flat immersed compact surface is greater than or equal to twice the absolute value of the Euler characteristic of the surface. A set of necessary and, in a weakened sense, sufficient...

  19. Current plate motions

    Science.gov (United States)

    Demets, C.; Gordon, R. G.; Argus, D. F.; Stein, S.

    1990-05-01

    A global plate motion model, named NUVEL-1, which describes current plate motions between 12 rigid plates is described, with special attention given to the method, data, and assumptions used. Tectonic implications of the patterns that emerged from the results are discussed. It is shown that wide plate boundary zones can form not only within the continental lithosphere but also within the oceanic lithosphere; e.g., between the Indian and Australian plates and between the North American and South American plates. Results of the model also suggest small but significant diffuse deformation of the oceanic lithosphere, which may be confined to small awkwardly shaped salients of major plates.

  20. Enhancement effects of flat-mirror reflection on plasma radiation.

    Science.gov (United States)

    Chen, Jin-zhong; Bai, Jin-ning; Song, Guang-ju; Sun, Jiang; Deng, Ze-chao; Wang, Ying-long

    2013-09-01

    Laser-induced breakdown spectroscopy quality can be improved by using a nanosecond Nd:YAG laser pulse to excite soil samples. To investigate how flat-mirror reflection affects the radiation characteristics of laser-induced plasma, emission spectra of sample elements were recorded using a grating spectrometer and photoelectric detection system. Placing a planar mirror vertically on the sample surface (10 mm mirror to plasma-center axis distance) for flat-mirror reflection increased spectral line intensities of Mg, Al, Fe, and Ba by 93.06%, 159.63%, 93.43%, and 94.61%, respectively. Signal-to-noise ratio increased by 17.56%, 40.21%, 31.29%, and 30%. The radiation enhancement mechanism was clarified using measured plasma parameters.

  1. Acquired vertical accommodative vergence.

    Science.gov (United States)

    Klein-Scharff, Ulrike; Kommerell, Guntram; Lagrèze, Wolf A

    2008-03-08

    Vertical accommodative vergence is an unusual synkinesis in which vertical vergence is modulated together with accommodation. It results from a supranuclear miswiring of the network normally conveying accommodative convergence. So far, it is unknown whether this condition is congenital or acquired. We identified an otherwise healthy girl who gradually developed vertical accommodative vergence between five to 13 years of age. Change of accommodation by 3 diopters induced a vertical vergence of 10 degrees. This observation proves that the miswiring responsible for vertical accommodative vergence must not necessarily be congenital, but can be acquired. The cause and the mechanism leading to vertical accommodative vergence are yet unknown.

  2. Entanglement entropy in flat holography

    Science.gov (United States)

    Jiang, Hongliang; Song, Wei; Wen, Qiang

    2017-07-01

    BMS symmetry, which is the asymptotic symmetry at null infinity of flat spacetime, is an important input for flat holography. In this paper, we give a holographic calculation of entanglement entropy and Rényi entropy in three dimensional Einstein gravity and Topologically Massive Gravity. The geometric picture for the entanglement entropy is the length of a spacelike geodesic which is connected to the interval at null infinity by two null geodesics. The spacelike geodesic is the fixed points of replica symmetry, and the null geodesics are along the modular flow. Our strategy is to first reformulate the Rindler method for calculating entanglement entropy in a general setup, and apply it for BMS invariant field theories, and finally extend the calculation to the bulk.

  3. Possible Problems: Inverted, Flat, or Pierced Nipples

    Science.gov (United States)

    ... Listen Español Text Size Email Print Share Possible Problems: Inverted, Flat, or Pierced Nipples Page Content Article ... a lesser extent flat nipples, can create a problem during breastfeeding by making it more difficult for ...

  4. On the aeroacoustic properties of a beveled plate

    NARCIS (Netherlands)

    Van der Velden, W.C.P.; Van Zuijlen, A.H.; De Jong, A.T.; Bijl, H.

    2015-01-01

    The flow around a beveled flat plate model with an asymmetric 25 degrees trailing edge with three rounding radii is analyzed using a Navier-Stokes based open source software package OpenFOAM in order to predict the aeroacoustic properties of the models. A Large Eddy Simulation with a dynamic

  5. Muddy Seafloors and Tidal Flats

    Science.gov (United States)

    2008-01-01

    and - Examine the processes leading to channel migration. Additional goals in FY08 relating to sandy coasts include analysis of waves, currents, and...shown in Figure 3. The seafloor was covered with a 30-cm thick layer of yogurt -like mud (density about 1.6 g/l [G. Kineke and S. Bentley]) that caused...project. Our observations on the macrotidal flat are part of a larger effort to investigate and model physical, geological, and morphological processes

  6. Representability of Hom implies flatness

    Indian Academy of Sciences (India)

    ... A basic result of Grothendieck ([EGA], III 7.7.9) says that if F is flat over then hom ( E , F ) is representable for all E . We prove the converse of the above, in fact, we show that if is a relatively ample line bundle on over such that the functor hom ( L − n , F ) is representable for infinitely many positive integers , then F ...

  7. Vertical external cavity surface emitting semiconductor lasers

    CERN Document Server

    Holm, M

    2001-01-01

    Active stabilisation showed a relative locked linewidth of approx 3 kHz. Coarse tuning over 7 nm was achieved using a 3-plate birefingent filter plate while fine-tuning using cavity length change allowed tuning over 250 MHz. Vertical external cavity semiconductor lasers have emerged as an interesting technology based on current vertical cavity semiconductor laser knowledge. High power output into a single transverse mode has attracted companies requiring good fibre coupling for telecommunications systems. The structure comprises of a grown semiconductor Bragg reflector topped with a multiple quantum well gain region. This is then included in an external cavity. This device is then optically pumped to promote laser action. Theoretical modelling of AIGaAs based VECSEL structures was undertaken, showing the effect of device design on laser characteristics. A simple 3-mirror cavity was constructed to assess the static characteristics of the structure. Up to 153 mW of output power was achieved in a single transver...

  8. A Note on Gorenstein Flat Dimension

    OpenAIRE

    Bennis, D.

    2008-01-01

    Unlike the Gorenstein projective and injective dimensions, the majority of results on the Gorenstein flat dimension have been established only over Noetherian (or coherent) rings. Naturally, one would like to generalize these results to any associative ring. In this direction, we show that the Gorenstein flat dimension is a refinement of the classical flat dimension over any ring; and we investigate the relations between the Gorenstein projective dimension and the Gorenstein flat dimension.

  9. Flat colon polyps: what should radiologists know?

    Energy Technology Data Exchange (ETDEWEB)

    Ignjatovic, A. [Intestinal Imaging Centre, St Mark' s Hospital, Harrow, Middlesex (United Kingdom); Burling, D., E-mail: burlingdavid@yahoo.co.u [Intestinal Imaging Centre, St Mark' s Hospital, Harrow, Middlesex (United Kingdom); Ilangovan, R.; Clark, S.K.; Taylor, S.A.; East, J.E.; Saunders, B.P. [Intestinal Imaging Centre, St Mark' s Hospital, Harrow, Middlesex (United Kingdom)

    2010-12-15

    With the recent publication of international computed tomography (CT) colonography standards, which aim to improve quality of examinations, this review informs radiologists about the significance of flat polyps (adenomas and hyperplastic polyps) in colorectal cancer pathways. We describe flat polyp classification systems and propose how flat polyps should be reported to ensure patient management strategies are based on polyp morphology as well as size. Indeed, consistency when describing flat polyps is of increasing importance given the strengthening links between CT colonography and endoscopy.

  10. Radiative Fluid Flow Between Fixed Vertical Plates With Suction ...

    African Journals Online (AJOL)

    Radiating MHD free convective slip flow with mass transfer and chemical reaction is presented. The governing particles are solved by perturbation method. The temperature, velocity and concentration profiles are presented graphically. The effects of magnetic, Prandtl, Schmidt, radiation, chemical, wave numbers are ...

  11. design, construction and evaluation of a vertical plate maize seed

    African Journals Online (AJOL)

    user

    society of Mechanical Engineers (ASME) code equation as shown in (18). d. √ K. K. In (18), d is the diameter of the shaft, Mb is the bending moment, Mt is the torsional moment, Kb is the combined shock and fatigue factor applied to bending moment, Kt is the combined shock and fatigue factor applied to torsional moment ...

  12. Unsteady MHD free convective flow past a vertical porous plate ...

    African Journals Online (AJOL)

    user

    been seen in MHD power generators, astrophysical and meteorological studies as well as in plasma physics. The Hall effect is due merely to ...... -3. Kg/ m ] fluid density in the boundary layer υ [ 2 -1. m s ] kinematic viscosity σ [ -1. -1. Ω m ] electrical conductivity θ [-] dimensionless temperature φ [. -3. Wm ] frictional heat. Ω [-].

  13. Unsteady MHD free convective flow past a vertical porous plate ...

    African Journals Online (AJOL)

    user

    2 Department of Mathematics, Gauhati University, Guwahati 781014, Assam, INDIA. 3 Department of ... Analytical solution has been found depending on the physical parameters including ... the attention of many scholars because of its possible applications in diverse fields of science and technology such as – soil- sciences ...

  14. Normal-Pressure Tests of Circular Plates with Clamped Edges

    Science.gov (United States)

    Mcpherson, Albert E; Ramberg, Walter; Levy, Samuel

    1942-01-01

    A fixture is described for making normal-pressure tests of flat plates 5 inches in diameter in which particular care was taken to obtain rigid clamping at the edges. Results are given for 19 plates, ranging in thickness form 0.015 to 0.072 inch. The center deflections and the extreme-fiber stresses at low pressures were found to agree with theoretical values; the center deflections at high pressures were 4 to 12 percent greater than the theoretical values. Empirical curves are derived of the pressure for the beginning of the permanent set as a function of the dimensions of the plate and the tensile properties of the material.

  15. Flat panel display - Impurity doping technology for flat panel displays

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Toshiharu [Advanced Technology Planning, Sumitomo Eaton Nova Corporation, SBS Tower 9F, 10-1, Yoga 4-chome, Setagaya-ku, 158-0097 Tokyo (Japan)]. E-mail: suzuki_tsh@senova.co.jp

    2005-08-01

    Features of the flat panel displays (FPDs) such as liquid crystal display (LCD) and organic light emitting diode (OLED) display, etc. using low temperature poly-Si (LTPS) thin film transistors (TFTs) are briefly reviewed comparing with other FPDs. The requirements for fabricating TFTs used for high performance FPDs and system on glass (SoG) are addressed. This paper focuses on the impurity doping technology, which is one of the key technologies together with crystallization by laser annealing, formation of high quality gate insulator and gate-insulator/poly-Si interface. The issues to be solved in impurity doping technology for state of the art and future TFTs are clarified.

  16. Vertical axis wind turbines

    Science.gov (United States)

    Krivcov, Vladimir [Miass, RU; Krivospitski, Vladimir [Miass, RU; Maksimov, Vasili [Miass, RU; Halstead, Richard [Rohnert Park, CA; Grahov, Jurij [Miass, RU

    2011-03-08

    A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

  17. Free vibration of rectangular plates with a small initial curvature

    Science.gov (United States)

    Adeniji-Fashola, A. A.; Oyediran, A. A.

    1988-01-01

    The method of matched asymptotic expansions is used to solve the transverse free vibration of a slightly curved, thin rectangular plate. Analytical results for natural frequencies and mode shapes are presented in the limit when the dimensionless bending rigidity, epsilon, is small compared with in-plane forces. Results for different boundary conditions are obtained when the initial deflection is: (1) a polynomial in both directions, and (2) the product of a polynomial and a trigonometric function, and arbitrary. For the arbitrary initial deflection case, the Fourier series technique is used to define the initial deflection. The results obtained show that the natural frequencies of vibration of slightly curved plates are coincident with those of perfectly flat, prestressed rectangular plates. However, the eigenmodes are very different from those of initially flat prestressed rectangular plates. The total deflection is found to be the sum of the initial deflection, the deflection resulting from the solution of the flat plate problem, and the deflection resulting from the static problem.

  18. Quantitative morphometric study of the subaxial cervical vertebrae end plate.

    Science.gov (United States)

    Feng, Hang; Fang, Xiangyi; Huang, Dageng; Yu, Chengcheng; Zhao, Songchuan; Hao, Dingjun

    2017-02-01

    Cervical disc arthroplasty has been gradually adopted as an alternative for the treatment of cervical degenerative disease. However, there is a large discrepancy between footprints of currently available cervical disc prostheses and anatomic dimensions of cervical end plates. This study aimed to accurately and comprehensively quantify the three-dimensional (3D) anatomic morphology of the cervical vertebral end plate and provide a theoretical basis for designing appropriate disc prostheses. Moreover, we introduced a novel geometric and mechanical model for 3D reconstruction techniques of the cervical end plate. A descriptive study of the geometry of the middle and lower cervical vertebral end plates in cadaveric spines was carried out. A total of 138 cervical vertebral end plates were digitized using an optical 3D range scanning system, and then each end plate was reconstructed using the digitized image. For each end plate, the morphologic characteristics of six surface curves and the end plate concavity depth were symmetrically chosen and depicted. The cranial end plates (relative to the disc) were concave and the caudal end plates were relatively flat at all disc levels, with mean concavity depths of 2.04 and 0.69 mm, respectively. For the caudal end plates, the end plate concavity apex was most often (81.42%) located in the posterior portion, whereas in the cranial end plates, the distribution was relatively even. For the sagittal curves, the foremost point and the rearmost point on the middle curve had a more forward position than those in the left curve and the right curve. Regarding the frontal plane curves, the length of the middle curve was longer than that of the anterior curve and posterior curve. For the cranial end plate, the maximal mean depth was the middle curve, whereas for the caudal end plate, the maximum depth was the posterior curve. There is marked morphologic asymmetry, in that the cranial end plate is more concave than the corresponding

  19. Growth Plate Injuries

    Science.gov (United States)

    ... plate injuries includes: Falling down. Competitive sports (like football). Recreational activities. Sometimes growth plate injuries happen when ... knee. For More Info U.S. Food and Drug Administration Toll free: 888-INFO-FDA (888-463-6332) ...

  20. Create Your Plate

    Science.gov (United States)

    ... Your Plate Gluten Free Diets Meal Planning for Vegetarian Diets Cook with Heart-Healthy Foods Holiday Meal ... Healthy Diet Create Your Plate Meal Planning for Vegetarian Diets Gluten Free Diets Holiday Meal Planning Cook ...