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Numerical simulation of turbulent flow and heat transfer in film cooling from a cylindrical hole in three-dimensional case is considered. For this purpose, turbulent heat flux term of energy equation is usually modeled by simple eddy diffusivity model with constant turbulent Prandtl number, while experimental and numerical researches show that the prescribed constant value of turbulent Prandtl number is far from reality. In the present study, second moment closure (SMC) models with wall-reflection term is applied for modeling the turbulent flow and heat transfer in film cooling flow. Comparison between the numerical and experimental results show that the explicit algebraic second moment closure models have more ability to better prediction of temperature field in film cooling. In addition, turbulent Prandtl number distribution for film cooling has been investigated. The range of this parameter for the desired geometry has been identified from 0.1 to 0.95 in the near of injection hole to far from it respectively. Finally, in order to enhance the capability of simple eddy diffusivity model in simulating film cooling heat transfer, the value of 0.7 has been proposed for turbulent Prandtl number instead of the common value of 0.85.

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This paper discusses about the effects of square wave pulsation on the turbulent flow and heat transfer from slot jet impinging to a concave surface. The RNG k-ε turbulence model is applied for modeling the turbulent flow and heat transfer filed in the present 2-D slot jet flow. The effects of jet Reynolds number, nozzle to surface distance and pulsation frequency on time-averaged Nusselt number distribution are studied carefully. Results show that applying the pulsating jet in the range of 10 Hz to 50 Hz can increase heat transfer from the concave surface in comparison with the steady jet. Increasing jet Reynolds number ranged from 4740 to 9590 significantly increases the time-averaged local Nusselt number. Also, in steady jet, decreasing the nozzle to surface distance, consequences increasing the Nusselt number near the impingement zone. While in pulsating jet, it causes both increasing/ decreasing the Nusselt number all over the concave surface.

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The nitrogen oxide emission is known as a potentially hazardous pollutant in reacting flows. To improve this process, it is of fundamental importance to take into consideration environment protection through reduction of fuel consumption in addition to increasing combustion efficiency. The control of NO emission from the combustion process is an important design criterion in modern gas turbine technology. In the present work a two-dimensional combustion simulation is developed for a model gas turbine combustion chamber. The k−ε turbulence model and the eddy dissipation concept model are applied for flow predictions and reaction rate simulation respectively. The flow field pressure linked equations are solved using the SIMPLE algorithm. In the present work, the thermal and prompt NO formations are estimated and calculated for three different methane, propane and pentane fuels. Also the effects of equivalence ratio and primary aeration on nitrogen oxide emission are considered. Results of numerical simulation show that the nitrogen oxide emission significantly affected by the equivalence ratio for all three type of fuels. Also by applying primary aeration the averaged nitrogen oxide production can be significantly reduced.