Film cooling effectiveness distribution of cylindrical hole injections at different locations on a vane endwall

The secondary flow vortices make the flow field near the endwall highly three-dimensional. The jet-to-secondary flow interaction may help to make an efficient film cooling arrangement to cool the endwall. Six rows of cylindrical hole injection placed at different locations on a typical flat vane endwall with different density ratios and matched averaged blowing ratios to the engine condition were investigated experimentally in this work. Detailed measurements of adiabatic film cooling effectiveness distribution using PSP technique as well as the pressure distribution of the endwall were performed. The results showed that the endwall film cooling was mainly influenced by the passage vortex and endwall cross flow which prevented the cooling jet from covering the regions close to the leading edge and pressure side. The theoretical analysis indicated that the local blowing ratio of endwall film cooling increased as the local static pressure increased. The cooling jets with higher local blowing ratios were more sensitive to the change of the coolant supply pressure. Film injections located in high static pressure zones with a high momentum flux ratio had the potential to reduce the intensity of secondary flow and provided coolant to the near leading edge and pressure side regions.