Investigation of the film-cooling and flow characteristics of trapezoidal slot scheme on the blade tip with partial pressure side squealer in transonic flow

The present work first introduces and studies the blade tip with a discrete trapezoidal slot scheme. The film-cooling characteristics of the discrete trapezoidal slot scheme on the blade tip with the partial pressure side squealer and full suction side squealer is experimentally investigated by the Pressure Sensitive Paint technique in transonic flow. The effects of the mass-flow-ratio and tip-clearance-gap are investigated, and the experiment is carried out at four mass-flow-ratios of 0.1% + 0.05%, 0.14% + 0.07%, 0.17% + 0.085%, and 0.21% + 0.105% and three tip-clearance-gaps of 0.7%, 1.1%, and 1.5%. The cascade exit Mach numbers is 1.05. The flow characteristics of the blade tip is studied by the calculation. The results indicate that the coolant can cover the whole blade tip bottom surface at the tip clearance of 1.5% and high mass-flow-ratios; With the tip-clearance-gap increasing, the adiabatic film effectiveness near the squealer rim of the suction side is significantly improved; The adiabatic film effectiveness near the leading edge at the small tip-clearance-gap is higher than that at the large tip-clearance-gap under the mass-flow-ratio of 0.1% + 0.05% condition due to the mainstream-blockage-effect; With the tip-clearance-gap increasing, the high aerodynamic loss coefficient region is significantly enlarged. At three tip-clearance-gaps, changing the mass-flow-ratio shows a slight effect on the aerodynamic loss coefficient distribution.