Experimental and numerical investigations of cooling characteristics on endwall partitioned film cooling with shaped holes

Abstract

The growing demand for high efficiency in gas turbines requires elevated turbine inlet temperatures, underscoring the critical necessity of implementing high-efficiency film cooling technology on the turbine endwall. However, the traditional cooling layout encounters challenges in the under-cooled areas on the turbine endwall. Therefore, a partitioned film cooling layout with shaped holes on the endwall was proposed based on the heat transfer and flow characteristics of the endwall and the cooling properties of the shaped holes. Based on the heat transfer coefficient distribution on the endwall surface, the endwall was divided into four regions, arranged with different shaped holes for cooling. Numerical and experimental methods were used to study the aerodynamic and cooling characteristics of the partitioned cooling layout. The results indicated that the partitioned cooling layout's cooling performance was significantly improved compared with that of the conventional film hole arrangement. Additionally, it was verified that adjusting the compound angle of the shaped holes further provided a uniform film coverage. More importantly, by adjusting the mass flow of the coolant, the optimized blowing ratios of different regions on the partitioned film cooling layout were explored. The optimized blowing ratio scheme significantly enhanced the film cooling effectiveness due to the varying sensitivity of different shaped holes to the blowing ratio. The results of this work hold significance for advancing film cooling effectiveness and turbine performance.