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This paper documents a computational investigation of the film cooling effectiveness of a 3-D gas turbine endwall with one fan-shaped cooling hole. The simulations were performed for adiabatic and conjugate heat transfer models. Turbulence closure was investigated using three different turbulence models; the realizable -model, the SST -model, as well as the 5 5 @ 0 % = #

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This paper documents a computational investigation of the film-cooling effectiveness of a 3-D gas turbine endwall with one cylindrical cooling hole. The simulations were performed for an adiabatic and conjugate heat transfer models. Turbulence closure was investigated using five different turbulence models; the standard k-ε model, the RNG k-ε model, the realizable k-ε model, the standard k-ε model, as well as the SST k-ω model. Results were obtained for a blowing ratio of 2.0, and a coolant-to-mainflow temperature ratio of 0.54. The simulations used a dense, high quality, O-type, hexahedral grid. The computed flow/temperature fields are presented, in addition to local, two-dimensional distribution of film cooling effectiveness for the adiabatic and conjugate cases. Results are compared to experimental data in terms of centerline film cooling effectiveness downstream cooling-hole, the predictions with realizable k-ε turbulence model exhibited the best agreement especially in the region for (x/D ≤ 6). All turbulence models predicted the jet lift-off. Also, the results show the effect of the conjugate heat transfer on the temperature (effectiveness) field in the film-cooling hole region and, thus, the additional heating up of the cooling jet itself.

An inverse methodology is developed as a means of determining heat transfer coefficient distributions in film cooling holes/slots. Thermal conditions are over-specified at exposed surfaces amenable to measurement, while the temperature and surface heat flux distributions are unknown at the film cooling hole/slot walls. The latter are determined in an iterative manner by solving an inverse problem whose objective is to adjust the film-cooling hole/slot wall temperatures and heat flux distributions until the temperature and heat fluxes at the measurement surfaces are matched in an overall heat conduction solution. The heat conduction problem is solved using boundary element methods, and the inverse problem is solved using a genetic algorithm. The resulting film coefficient distributions are fit to a correlation reflecting dependency on position, the Prandtl and Reynolds numbers.