Effect of Endwall Contouring in presence of Upstream Leakage Flow in a Transonic Turbine Blade Passage: Heat Transfer Measurements

摘要

Comparison of heat transfer performance of a non-axi symmetric contoured endwall to a non-contoured baseline endwall in presence of leakage flow through stator-rotor rim seal interface is reported in this paper. Heat transfer experiments were performed on a high turning (～127°) turbine airfoil passage under transonic exit Mach number conditions at three leakage to mainstream mass flow ratios, 0.5%, 1% and 1.5% respectively. The contoured endwall geometry was generated to minimize stagnation and secondary aerodynamic losses. Transient IR (Infrared) thermography technique was applied to measure endwall surface temperature and calculation of simultaneous of heat transfer coefficient (HTC) and cooling effectiveness (ETA) was performed assuming a 1D semi-infinite transient conduction. Results show considerable reduction in area averaged HTC using the contoured endwall compared to baseline endwall with different levels of coolant MFRs, whereas, significant reduction was achieved for cases without coolant flow and without purge slot. A decrease in HTC values near the leading edge region was prominent comparing with and without purge slot cases for respective geometries. The backward facing step seems to have a significant impact on endwall HTC distribution rather than with coolant blowing cases.