Effects of Slot Injection and Leakage Gap on Heat Transfer Characteristics of an Axisymmetric Turbine Endwall

In order to investigate the effects of slot injection and leakage gap on the heat transfer characteristics of an axisymmetric vane endwall of first-stage turbine, an experiment was conducted in a high-speed wind tunnel using steady-state temperature measurement technology with the R35C15W type wide-band liquid crystal to study the heat transfer performance of the endwall. For the cases without slot injection, the effects of the Reynolds numbers (Re=2.2×105, 2.8×105 and 3.4×105) on endwall heat transfer characteristics were investigated. For the cases with slot injection, the influences of mass flow ratio (0.6%, 0.85% and 1.08%) and leakage gap width (3.93mm and 7.86mm) were studied respectively. The results show that endwall heat transfer coefficient of the region near suction surface is higher than that of the region near pressure surface under the effect of leakage vortex, and with the increase of the Reynolds number, the heat transfer amplification rate of the area near the pressure surface and suction surface are 18% and 15%, respectively. The slot injection enhances the disturbance of flow field on the endwall surface while diminishing the strength of the horseshoe vortex and the leakage vortex, which leads to the augmentation of endwall heat transfer coefficient. With the increase of the jet mass flow ratio, the heat transfer increase rate in the area upstream of the leading edge are 12%, 34% and 40%, in the area near the pressure surface are 15%, 33% and 42%, in the area around the suction surface are 11%, 24% and 31% compared with the non-cooled jet. Moreover, decreasing the width of leakage gap reduces the heat transfer coefficient upstream of the vane leading edge by 17%. © 2022, Editorial Department of Journal of Propulsion Technology. All right reserved.