Measurements of film cooling performance in a transonic single passage model

Film cooling is an essential technology for the development of high performance gas turbine engines. A well-designed film cooling strategy allows higher turbine inlet temperatures, improving the engine thermodynamic efficiency. Accurate prediction tools are vital for designers. With the increasing complexity of cooling designs, correlations and incremental design approaches have become outdated, signaling the urgent need for "physics-based" tools that can be coupled to standard modern computational tools, such as commercial computational fluid dynamics (CFD) codes. A glaring problem with the development of this new technology is the lack of well-resolved data with well-defined boundary conditions. Thus, a frequent problem facing model developers is elucidating if differences between experimental data and predictions are due to the experimental data, the applied model, or the boundary conditions.; The purpose of this experiment is to provide highly resolved film cooling performance and heat transfer coefficient measurements of compound angle round holes coupled with realistic gas turbine engine blade geometry and flow conditions. The ultimate goals are: (1) to develop an experimental procedure than can provide timely data for film cooling design; (2) provide full-field surface film cooling data for developing computational models in realistic flows. An experimental two-dimensional representation of the flow field between two modern, transonic turbine airfoil surfaces was used in these tests.; The spatially-resolved heat transfer measurements collected in this facility revealed several intriguing results: the thermal boundary layer that forms on a typical airfoil surface is relatively insensitive to the inlet level of turbulence once the mainstream flow accelerates to supersonic conditions. Additionally, these data also suggest that the heat transfer coefficient can depend on the local surface heat flux boundary condition---inferring that standard variable heat flux measurement techniques used in turbomachinery have an inherent error that can corrupt the subsequent measurements. The film cooling results indicate two regimes for jet-in-crossflow interaction: one where the jet is rapidly entrained into the local boundary layer, the other where the jet blows straight through the boundary layer. The effect of different parameters on the cooling performance was found to be highly dependent on the jet regime.