The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
M A Sattar - One of the best experts on this subject based on the ideXlab platform.
-
on the effectiveness of viscous dissipation and joule heating on steady magnetohydrodynamic heat and mass transfer flow over an inclined radiate isothermal permeable surface in the presence of thermophoresis
Communications in Nonlinear Science and Numerical Simulation, 2009Co-Authors: M S Alam, M M Rahman, M A SattarAbstract:Abstract The combined effect of viscous dissipation and joule heating on steady Magnetohydrodynamic heat and mass transfer flow of viscous incompressible fluid over an inclined radiate isothermal permeable surface in the presence of thermophoresis is studied. Numerical results for the dimensionless velocity, temperature and concentration profiles as well as the local skin-friction coefficient, the local Nusselt Number and the local Stanton Number are displayed graphically for various physical parameters. Comparisons with previously published work are performed and the results are found to be in very good agreement. Results show that rate of heat transfer is sensitive for increasing angle of inclination parameter for the case of fluid injection and it decreases with the increase of magnetic field parameter and Eckert Number.
-
on the effectiveness of viscous dissipation and joule heating on steady magnetohydrodynamic heat and mass transfer flow over an inclined radiate isothermal permeable surface in the presence of thermophoresis
Communications in Nonlinear Science and Numerical Simulation, 2009Co-Authors: M S Alam, M M Rahman, M A SattarAbstract:Abstract The combined effect of viscous dissipation and joule heating on steady Magnetohydrodynamic heat and mass transfer flow of viscous incompressible fluid over an inclined radiate isothermal permeable surface in the presence of thermophoresis is studied. Numerical results for the dimensionless velocity, temperature and concentration profiles as well as the local skin-friction coefficient, the local Nusselt Number and the local Stanton Number are displayed graphically for various physical parameters. Comparisons with previously published work are performed and the results are found to be in very good agreement. Results show that rate of heat transfer is sensitive for increasing angle of inclination parameter for the case of fluid injection and it decreases with the increase of magnetic field parameter and Eckert Number.
-
transient magnetohydrodynamic free convective heat and mass transfer flow with thermophoresis past a radiate inclined permeable plate in the presence of variable chemical reaction and temperature dependent viscosity
Nonlinear Analysis-Modelling and Control, 2009Co-Authors: M S Alam, M M Rahman, M A SattarAbstract:In the present study, an analysis is carried out to investiga te the effects of variable chemical reaction, thermophoresis, temperature-dependent viscosity and thermal radiation on an unsteady MHD free convective heat and mass transfer flow of a viscous, incompressible, electrically conducting fluid past an impu lsively started infinite inclined porous plate. The governing nonlinear partial differentia l equations are transformed into a system of ordinary differential equations, which are solved numerically using a sixth-order Runge-Kutta integration scheme with Nachtsheim-Swigert shooting method. Numerical results for the non-dimensional velocity, temperature and concentration profiles as well as the local skin-friction coefficient, the l ocal Nusselt Number and the local Stanton Number are presented for different physical parameters. The results show that variable viscosity significantly increases viscous dr ag and rate of heat transfer. The results also show that higher order chemical reaction induces the concentration of the particles for a destructive reaction and reduces for a gener ative reaction.
M S Alam - One of the best experts on this subject based on the ideXlab platform.
-
on the effectiveness of viscous dissipation and joule heating on steady magnetohydrodynamic heat and mass transfer flow over an inclined radiate isothermal permeable surface in the presence of thermophoresis
Communications in Nonlinear Science and Numerical Simulation, 2009Co-Authors: M S Alam, M M Rahman, M A SattarAbstract:Abstract The combined effect of viscous dissipation and joule heating on steady Magnetohydrodynamic heat and mass transfer flow of viscous incompressible fluid over an inclined radiate isothermal permeable surface in the presence of thermophoresis is studied. Numerical results for the dimensionless velocity, temperature and concentration profiles as well as the local skin-friction coefficient, the local Nusselt Number and the local Stanton Number are displayed graphically for various physical parameters. Comparisons with previously published work are performed and the results are found to be in very good agreement. Results show that rate of heat transfer is sensitive for increasing angle of inclination parameter for the case of fluid injection and it decreases with the increase of magnetic field parameter and Eckert Number.
-
on the effectiveness of viscous dissipation and joule heating on steady magnetohydrodynamic heat and mass transfer flow over an inclined radiate isothermal permeable surface in the presence of thermophoresis
Communications in Nonlinear Science and Numerical Simulation, 2009Co-Authors: M S Alam, M M Rahman, M A SattarAbstract:Abstract The combined effect of viscous dissipation and joule heating on steady Magnetohydrodynamic heat and mass transfer flow of viscous incompressible fluid over an inclined radiate isothermal permeable surface in the presence of thermophoresis is studied. Numerical results for the dimensionless velocity, temperature and concentration profiles as well as the local skin-friction coefficient, the local Nusselt Number and the local Stanton Number are displayed graphically for various physical parameters. Comparisons with previously published work are performed and the results are found to be in very good agreement. Results show that rate of heat transfer is sensitive for increasing angle of inclination parameter for the case of fluid injection and it decreases with the increase of magnetic field parameter and Eckert Number.
-
transient magnetohydrodynamic free convective heat and mass transfer flow with thermophoresis past a radiate inclined permeable plate in the presence of variable chemical reaction and temperature dependent viscosity
Nonlinear Analysis-Modelling and Control, 2009Co-Authors: M S Alam, M M Rahman, M A SattarAbstract:In the present study, an analysis is carried out to investiga te the effects of variable chemical reaction, thermophoresis, temperature-dependent viscosity and thermal radiation on an unsteady MHD free convective heat and mass transfer flow of a viscous, incompressible, electrically conducting fluid past an impu lsively started infinite inclined porous plate. The governing nonlinear partial differentia l equations are transformed into a system of ordinary differential equations, which are solved numerically using a sixth-order Runge-Kutta integration scheme with Nachtsheim-Swigert shooting method. Numerical results for the non-dimensional velocity, temperature and concentration profiles as well as the local skin-friction coefficient, the l ocal Nusselt Number and the local Stanton Number are presented for different physical parameters. The results show that variable viscosity significantly increases viscous dr ag and rate of heat transfer. The results also show that higher order chemical reaction induces the concentration of the particles for a destructive reaction and reduces for a gener ative reaction.
M M Rahman - One of the best experts on this subject based on the ideXlab platform.
-
on the effectiveness of viscous dissipation and joule heating on steady magnetohydrodynamic heat and mass transfer flow over an inclined radiate isothermal permeable surface in the presence of thermophoresis
Communications in Nonlinear Science and Numerical Simulation, 2009Co-Authors: M S Alam, M M Rahman, M A SattarAbstract:Abstract The combined effect of viscous dissipation and joule heating on steady Magnetohydrodynamic heat and mass transfer flow of viscous incompressible fluid over an inclined radiate isothermal permeable surface in the presence of thermophoresis is studied. Numerical results for the dimensionless velocity, temperature and concentration profiles as well as the local skin-friction coefficient, the local Nusselt Number and the local Stanton Number are displayed graphically for various physical parameters. Comparisons with previously published work are performed and the results are found to be in very good agreement. Results show that rate of heat transfer is sensitive for increasing angle of inclination parameter for the case of fluid injection and it decreases with the increase of magnetic field parameter and Eckert Number.
-
on the effectiveness of viscous dissipation and joule heating on steady magnetohydrodynamic heat and mass transfer flow over an inclined radiate isothermal permeable surface in the presence of thermophoresis
Communications in Nonlinear Science and Numerical Simulation, 2009Co-Authors: M S Alam, M M Rahman, M A SattarAbstract:Abstract The combined effect of viscous dissipation and joule heating on steady Magnetohydrodynamic heat and mass transfer flow of viscous incompressible fluid over an inclined radiate isothermal permeable surface in the presence of thermophoresis is studied. Numerical results for the dimensionless velocity, temperature and concentration profiles as well as the local skin-friction coefficient, the local Nusselt Number and the local Stanton Number are displayed graphically for various physical parameters. Comparisons with previously published work are performed and the results are found to be in very good agreement. Results show that rate of heat transfer is sensitive for increasing angle of inclination parameter for the case of fluid injection and it decreases with the increase of magnetic field parameter and Eckert Number.
-
transient magnetohydrodynamic free convective heat and mass transfer flow with thermophoresis past a radiate inclined permeable plate in the presence of variable chemical reaction and temperature dependent viscosity
Nonlinear Analysis-Modelling and Control, 2009Co-Authors: M S Alam, M M Rahman, M A SattarAbstract:In the present study, an analysis is carried out to investiga te the effects of variable chemical reaction, thermophoresis, temperature-dependent viscosity and thermal radiation on an unsteady MHD free convective heat and mass transfer flow of a viscous, incompressible, electrically conducting fluid past an impu lsively started infinite inclined porous plate. The governing nonlinear partial differentia l equations are transformed into a system of ordinary differential equations, which are solved numerically using a sixth-order Runge-Kutta integration scheme with Nachtsheim-Swigert shooting method. Numerical results for the non-dimensional velocity, temperature and concentration profiles as well as the local skin-friction coefficient, the l ocal Nusselt Number and the local Stanton Number are presented for different physical parameters. The results show that variable viscosity significantly increases viscous dr ag and rate of heat transfer. The results also show that higher order chemical reaction induces the concentration of the particles for a destructive reaction and reduces for a gener ative reaction.
Michael G Dunn - One of the best experts on this subject based on the ideXlab platform.
-
heat transfer for the film cooled vane of a 1 1 2 stage high pressure transonic turbine part i experimental configuration and data review with inlet temperature profile effects
Journal of Turbomachinery-transactions of The Asme, 2013Co-Authors: Harika S Kahveci, Randall M Mathison, C W Haldeman, Michael G DunnAbstract:This paper investigates the vane airfoil and inner endwall heat transfer for a full-scale turbine stage operating at design corrected conditions under the influence of different vane inlet temperature profiles and vane cooling flow rates. The turbine stage is a modern 3D design consisting of a cooled high-pressure vane, an un-cooled high-pressure rotor, and a low-pressure vane. Inlet temperature profiles (uniform, radial, and hot streaks) are created by a passive heat exchanger and can be made circumferentially uniform to within ±5% of the bulk average inlet temperature when desired. The high-pressure vane has full cooling coverage on both the airfoil surface and the inner and outer endwalls. Two circuits supply coolant to the vane, and a third circuit supplies coolant to the rotor purge cavity. All of the cooling circuits are independently controlled. Measurements are performed using double-sided heat-flux gauges located at four spans of the vane airfoil surface and throughout the inner endwall region. Analysis of the heat transfer measured for the uncooled downstream blade row has been reported previously. Part I of this paper describes the operating conditions and data reduction techniques utilized in this analysis, including a novel application of a traditional statistical method to assign confidence limits to measurements in the absence of repeat runs. The impact of Stanton Number definition is discussed while analyzing inlet temperature profile shape effects. Comparison of the present data (Build 2) to the data obtained for an uncooled vane (Build 1) clearly illustrates the impact of the cooling flow and its relative effects on both the endwall and airfoils. Measurements obtained for the cooled hardware without cooling applied agree well with the solid airfoil for the airfoil pressure surface but not for the suction surface. Differences on the suction surface are due to flow being ingested on the pressure surface and reinjected on the suction surface when coolant is not supplied for Build 2. Part II of the paper continues this discussion by describing the influence of overall cooling level variation and the influence of the vane trailing edge cooling on the vane heat transfer measurements.
-
heat transfer for the blade of a cooled stage and one half high pressure turbine part i influence of cooling variation
Journal of Turbomachinery-transactions of The Asme, 2012Co-Authors: Randall M Mathison, C W Haldeman, Michael G DunnAbstract:Heat-flux measurements are presented for a one-and-one-half stage high-pressure turbine operating at design-corrected conditions with modulated cooling flows in the presence of different inlet temperature profiles. Coolant is supplied from a heavily film-cooled vane and the purge cavity (between the rotor disk and the upstream vane) but not from the rotor blades, which are solid metal. Thin-film heat-flux gauges are located on the uncooled blade pressure and suction surface (at multiple span locations), on the blade tip, on the blade platform, and on the disk and vane sides of the purge cavity. These measurements provide a comprehensive picture of the effect of varying cooling flow rates on surface heat transfer to the turbine blade for uniform and radial inlet temperature profiles. Part I of this paper examines the macroscopic influence of varying all cooling flows together, while Part II investigates the individual regions of influence of the vane outer and purge cooling circuits in more detail. The heat-flux gauges are able to track the cooling flow over the suction surface of the airfoil as it wraps upwards along the base of the airfoil for the uniform vane inlet temperature profile. A similar comparison for the radial profile shows the same coolant behavior but with less pronounced changes. From these comparisons, it is clear that cooling impacts each temperature profile similarly. Nearly all of the cooling influence is limited to the blade suction surface, but small changes are observed for the pressure surface. In addition to the cooling study, a novel method of calculating the adiabatic wall temperature is demonstrated. The derived adiabatic wall temperature distribution shows very similar trends to the Stanton Number distribution on the blade.
-
heat transfer for the film cooled vane of a 1 1 2 stage high pressure transonic turbine part i experimental configuration and data review with inlet temperature profile effects
ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition, 2011Co-Authors: Harika S Kahveci, Randall M Mathison, C W Haldeman, Michael G DunnAbstract:This paper investigates the vane airfoil and inner endwall heat transfer for a full-scale turbine stage operating at design corrected conditions under the influence of different vane inlet temperature profiles and vane cooling flow rates. The turbine stage is a modern 3-D design consisting of a cooled high-pressure vane, an un-cooled high-pressure rotor, and a low-pressure vane. Inlet temperature profiles (uniform, radial and hot streaks) are created by a passive heat exchanger and can be made circumferentially uniform to within ±5% of the bulk average inlet temperature when desired. The high-pressure vane has full cooling coverage on both the airfoil surface and the inner and outer endwalls. Two circuits supply coolant to the vane, and a third circuit supplies coolant to the rotor purge cavity. All of the cooling circuits are independently controlled. Measurements are performed using double-sided heat-flux gauges located at four spans of the vane airfoil surface and throughout the inner endwall region. Analysis of the heat transfer measured for the uncooled downstream blade row has been reported previously. Part I of this paper describes the operating conditions and data reduction techniques utilized in this analysis, including a novel application of a traditional statistical method to assign confidence limits to measurements in the absence of repeat runs. The impact of Stanton Number definition is discussed while analyzing inlet temperature profile shape effects. Comparison of the present data (Build 2) to the data obtained for an un-cooled vane (Build 1) clearly illustrates the impact of the cooling flow and its relative effects on both the endwall and airfoils. Measurements obtained for the cooled hardware without cooling applied agree well with the solid air-foil for the airfoil pressure surface but not for the suction surface. Differences on the suction surface are due to flow being ingested on the pressure surface and re-injected on the suction surface when coolant is not supplied for Build 2. Part II of the paper continues this discussion by describing the influence of overall cooling level variation and the influence of the vane trailing edge cooling on the vane heat transfer measurements.Copyright © 2011 by ASME
-
heat transfer for the blade of a cooled stage and one half high pressure turbine part i influence of cooling variation
ASME Turbo Expo 2010: Power for Land Sea and Air, 2010Co-Authors: Randall M Mathison, C W Haldeman, Michael G DunnAbstract:Heat-flux measurements are presented for a one-and-one-half stage high-pressure turbine operating at design corrected conditions with modulated cooling flows in the presence of different inlet temperature profiles. Coolant is supplied from a heavily film cooled vane and the purge cavity (between the rotor disk and the upstream vane) but not from the rotor blades, which are solid metal. Thin-film heat-flux gauges are located on the un-cooled blade pressure and suction surface (at multiple span locations), on the blade tip, on the blade platform, and on the disk and vane sides of the purge cavity. These measurements provide a comprehensive picture of the effect of varying cooling flow rates on surface heat transfer to the turbine blade for uniform and radial inlet temperature profiles. Part I of this paper examines the macroscopic influence of varying all cooling flows together, while Part II investigates the individual regions of influence of the vane outer and purge cooling circuits in more detail. The heat-flux gauges are able to track the cooling flow over the suction surface of the airfoil as it wraps upwards along the base of the airfoil for the uniform vane inlet temperature profile. A similar comparison for the radial profile shows the same coolant behavior but with less pronounced changes. From these comparisons, it is clear that cooling impacts each temperature profile similarly. Nearly all of the cooling influence is limited to the blade suction surface, but small changes are observed for the pressure surface. In addition to the cooling study, a novel method of calculating the adiabatic wall temperature is demonstrated. The derived adiabatic wall temperature distribution shows very similar trends to the Stanton Number distribution on the blade.Copyright © 2010 by ASME
Parviz Moin - One of the best experts on this subject based on the ideXlab platform.
-
shock induced heating and transition to turbulence in a hypersonic boundary layer
arXiv: Fluid Dynamics, 2020Co-Authors: Michael Karp, Parviz Moin, Sanjeeb Bose, Javier UrzayAbstract:The interaction between an incident shock wave and a Mach-6 undisturbed hypersonic laminar boundary layer over a cold wall is addressed using direct numerical simulations (DNS) and wall-modeled large-eddy simulations (WMLES) at different angles of incidence. At sufficiently high shock-incidence angles, the boundary layer transitions to turbulence via breakdown of near-wall streaks shortly downstream of the shock impingement, without the need of any inflow free-stream disturbances. The transition causes a localized significant increase in the Stanton Number and skin-friction coefficient, with high incidence angles augmenting the peak thermomechanical loads in an approximately linear way. Statistical analyses of the boundary layer downstream of the interaction for each case are provided that quantify streamwise spatial variations of the Reynolds analogy factors and indicate a breakdown of the Morkovin's hypothesis near the wall, where velocity and temperature become correlated. A modified strong Reynolds analogy with a fixed turbulent Prandtl Number is observed to perform best. Conventional transformations fail at collapsing the mean velocity profiles on the incompressible log law. The WMLES prompts transition and peak heating, delays separation, and advances reattachment, thereby shortening the separation bubble. When the shock leads to transition, WMLES provides predictions of DNS peak thermomechanical loads within $\pm 10\%$ at a computational cost lower than DNS by two orders of magnitude. Downstream of the interaction, in the turbulent boundary layer, WMLES agrees well with DNS results for the Reynolds analogy factor, the mean profiles of velocity and temperature, including the temperature peak, and the temperature/velocity correlation.
-
transitional and turbulent boundary layer with heat transfer
Physics of Fluids, 2010Co-Authors: Parviz MoinAbstract:We report on our direct numerical simulation of an incompressible, nominally zero-pressure-gradient flat-plate boundary layer from momentum thickness Reynolds Number 80–1950. Heat transfer between the constant-temperature solid surface and the free-stream is also simulated with molecular Prandtl Number Pr=1. Skin-friction coefficient and other boundary layer parameters follow the Blasius solutions prior to the onset of turbulent spots. Throughout the entire flat-plate, the ratio of Stanton Number and skin-friction St/Cf deviates from the exact Reynolds analogy value of 0.5 by less than 1.5%. Mean velocity and Reynolds stresses agree with experimental data over an extended turbulent region downstream of transition. Normalized rms wall-pressure fluctuation increases gradually with the streamwise growth of the turbulent boundary layer. Wall shear stress fluctuation, τw,rms′+, on the other hand, remains constant at approximately 0.44 over the range, 800
