Experimental and Numerical Investigations on Turbine Airfoil Cooling Designs Part I- An Investigation on Flow Features by Particle Image Velocimetry

摘要

Experimental and numerical investigations are conducted to understand the features of the fluid dynamics within double-wall film-cooled configurations. Based on the similarity principle of the Reynolds number, a large-scale similar configuration made of transparent material is used as specimen, and the fluid velocity distributions over several typical cross sections within the specimen channel are captured by a particle image velocimetry (PIV) system. The experiments are carried out at a density ratio of fluid medium to tracer particle 1.05. The flow features are respectively calculated by different turbulence models and numerical grids. To confirm turbulence models and numerical grids, the numerical results are compared with the experimental data obtained by the PIV system. Through the comparisons, recommendations have been made with regard to the best model and numerical grid which best predict such velocity fields. The influences of inlet Reynolds numbers and the geometrical device of the double-wall film-cooled configurations on the features of flow field are numerically simulated by the recommended model and grid. The simulation results predicate that the flow features are mainly dominated by the geometrical device, the inlet Reynolds number can only result in a magnitude change of velocity fields, and this change is almost linear. This is the first part of the entire investigations on the double-wall film-cooled configurations, and the objective of this part is to confirm a suitable mathematical model and numerical grid for describing the flow features. In the next part, the overall heat transfer characteristics of these configurations will be studied.