On a Curved Cavity Floor Design Based on Heat Transfer Coefficient Distribution for a Turbine Blade Squealer Tip

The squealer tip has undergone extensive research and development in gas turbine blade applications. One of the persistent challenges is the high-temperature wear on the cavity floor, which has significant implications for turbine reliability. The intense thermal load on the cavity floor is primarily driven by the impingement and scraping effects of leakage flow. To address this issue, a numerical study is conducted to explore an optimization technique for the squealer tip by modifying the internal surface of the cavity using curved floor designs. Two variants are considered: a convex floor (Case_up) and a concave floor (Case_down). In addition, the effects of different floor deformation amplitudes (D) on the flow behavior and heat transfer characteristics are further investigated. Results indicate that the convex configuration increases the thermal load, intensifying heat accumulation on the cavity floor, while the concave design reduces both the peak heat transfer coefficient and the overall high-temperature area by 11.72% and 32.29%, respectively. The improvement observed in Case_down is attributed to a shift in the impingement pattern, where leakage flow scraping replaces its direct impingement, particularly as D exceeds 1.0 mm. In such cases, the leakage flow is directed away from the floor, leading to a significant reduction in thermal loads. Finally, the concave cavity floor configuration is incorporated into the squealer tip with rail-crown film holes, demonstrating its robust applicability under coolant injection conditions. The results indicate that the convex cavity floor effectively promotes coolant reattachment, thereby further enhancing the overall tip cooling performance.