Multi-row film cooling characteristics on a vane endwall

Abstract

The secondary flow vortices make the flow field near the endwall highly three-dimensional. The jet-to-secondary flow interaction and the interaction between multiple film rows are important for the understanding of endwall film cooling characteristics and the improvement of prediction method. Single row film cooling, three combinations of two-row film cooling as well as a full coverage configuration with five rows of film cooling on a typical flat vane endwall with matched averaged blowing ratios and density ratio to the engine condition were investigated experimentally. Detailed measurements of adiabatic film cooling effectiveness distribution using PSP technique as well as the pressure distribution of the endwall were performed. The single row film cooling results were used to test the applicability of the superposition law on the prediction of endwall multi-row film cooling effectiveness compared to the multi-row experimental results. The results indicated that the superposition method could not give quantitatively reliable film cooling effectiveness of the endwall multi-row cases especially for the full coverage film cooling configuration. The upstream film injections could alter the endwall secondary flow and affect the coolant spreading of the downstream row. Moreover the interaction between the downstream and upstream injections increased the mixing loss and induced a higher turbulence level which made the coolant from the upstream row dissipate faster.