Design and performance analysis of a vane shaped rotating receiver hole in high radius pre-swirl systems for gas turbine cooling

Abstract

In a pre-swirl cooling air delivery system for gas turbine, the function of rotating receiver hole is to receive the highly swirled flow from pre-swirl nozzle and direct it to the turbine blade supply hole. The geometry of the receiver hole and its relative velocity to the airflow are critical to the aerodynamic losses and cooling performance of the system. Two vane shaped (VS) receiver hole, which can realize the smooth connecting and matching between the stationary pre-swirl nozzle and rotating turbine blade supply hole, were designed here. The performance comparison between these high radius systems with VS receiver hole and a traditional direct transfer system (Baseline) was carried out. The results show that the nondimensional static pressure in pre-swirl cavity for the Baseline is 1.06 and the temperature drop effectiveness (ηt) is 0.31. While the value of ηt for the system with VS receiver hole increases by 35%, and the nondimensional static pressure reduces to 1.03. Moreover, the improved model Case-2, in which the receiver hole and supply hole connected to each other and the cover cavity was removed, has the lowest nondimensional static pressure of 0.98 and the highest temperature drop effectiveness of 0.71, more than double that of the Baseline model. The matching of rotating-stationary components and rotating-rotating components was described and implemented through the design of VS receiver holes. Flow field analysis was performed out to reveal the mechanism of losses occurred at interfaces of components. A comparison of low radius pre-swirl and high radius pre-swirl systems was also carried out. In the design of high radius pre-swirl systems, the swirl ratio in the system cannot be adjusted by applying an impeller due to the lack of radial space. This makes the VS receiver hole particularly suitable for high radius systems, to help the system achieving dual advantages of high temperature drop and low outer seal leakage.