Film cooling improvement of dovetail hole compared to cylindrical hole at different hole row locations on nozzle guide vane

Abstract

The profile curvature and boundary layer flow pattern at different positions of nozzle guide vane of aero engine resulted in the improvement differences in the film cooling performance of the shaped hole. In this paper, the two-dimensional distributions of temperatures of wall surface downstream single row of dovetail hole and cylindrical hole were examined at four typical locations by infrared thermal imaging technology in the linear cascade. The film effectiveness, heat transfer coefficient and heat flux ratio were analyzed. The results show that the improvements of spanwise averaged film effectiveness become small in the main-stream direction. At blowing ratios of 1.0–2.0, the improvements of film effectiveness are 92.3%–177.8% at SS1 location, 53.8%–75.1% at SS2 location, 42.6%–79.2% at PS1 location and 206.4%–388.4% at PS2 location, respectively. Heat transfer coefficients reduced by film cooling are found near the hole on the suction side. Heat transfer coefficient ratios increase on the suction side and slightly decrease on the pressure side in the mainstream direction. The maximum improvement based on film effectiveness occurs at the PS2 position, while the most effective improvement based on the heat flux ratio occurs at the SS1 position.