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Computational Simulation of Turbulent Incompressible Film Cooling with Consideration of Jet and Cross Flow Density and Viscosity Differences

Salimi, Mohammad Reza | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39403 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Taibi Rahni, Mohammad
  7. Abstract:
  8. One of the most powerful means to increase thermal efficiency in gas turbines is to increase the turbine inlet temperature. However, due to metallurgical limitations, the turbine blades need to be cooled constantly. Thus, film cooling of blades has shown to be the most efficient way. In this study, a three-dimensional film cooling problem at jet Reynolds number of 4700 are investigated, using RANS approach and three different turbulence models, namely (Wilcox), SST(Shear Stress Transport), and the new model. A fine non-uniform staggered grid and a SIMPLE based finite volume method were used. Film cooling simulation results, including mean velocity components and turbulent kinetic energy at different planes after the jet exit, were compared with reliable experimental results at density ratio of unity. The model results were in very good agreements whit the experimental data. Velocity and density ratios variation effects on the flow structures and film cooling effectiveness were studied as well. To do that, three different density ratios of 0.5, 1.0 and 2.0 were applied with three velocity ratios of 0.5, 1.0 and 2.0. It was observed that applying a gas with different density (as a jet flow) could increase or decrease the adiabatic effectiveness, depending on the jet velocity ratio. We also introduced a new jets configuration by placing another very low blowing ratio cooling port just upstream of the main jet. Our results show that this new approach improves film cooling effectiveness and skin friction drag coefficient considerably
  9. Keywords:
  10. Film Cooling ; Turbulence Modeling ; Large Density Ratio ; Upstream Jet

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