On the Aero-Thermal Performance of Rim Film Cooling in the Squealer Tip of a Linear Turbine Cascade

The present study proposes a novel rim film cooling design, motivated by the fact that the suction-side rim and the cavity floor near the leading edge of a conventional squealer tip with a camber-line film hole array are directly subjected to high-temperature gas. The new design consists of cooling injection for rim-hole or -slot cooling at the leading edge. The parameters of injection geometry and cavity depth are also discussed in this study. The flow physics, leakage flowrate, heat transfer characteristics, and vortices in the cavity are carefully analyzed. The results show that rim film cooling can substantially inhibit tip heat transfer and the amount of hot leakage flow. Compared with the typical design, the maximum and average heat transfer coefficients of the blade tip of the rim slot case are reduced by 12.83% and 5.43%,, respectively. The variation in cavity depth is sensitive to the heat transfer on the cavity floor of the squealer tip blade. With the optimal design, the average and maximum heat transfer coefficients are reduced by 14.42% and 14.21%,, respectively. In addition, the leakage flowrate can be reduced by a maximum of 3.67% by rim injection compared with the conventional squealer tip.