Theoretical study on showerhead film cooling effectiveness of adjustable guide vane installation angle for variable cycle Aeroengine

As a critical component of variable cycle engine, the adjustable turbine guide vane adapts to the aero-engine flow requirements by varying its installation angle (θ). However, research on film cooling techniques for adjustable turbine guide vanes is still insufficient. In this study, we conducted an investigation into showerhead film cooling, measuring its cooling efficiency using pressure-sensitive paint, and analyzing its flow characteristics through numerical simulations. Furthermore, three improved cooling schemes for showerhead cooling of adjustable turbine guide vane were proposed and compared for their enhancement effects. The results indicate that a decrease in installation angle leads to a shift of the stagnation line on the leading edge towards the pressure side and a reduction in the passage area, resulting in an increase in the pressure coefficients on both the suction and pressure sides. At the same time, installation angle significantly affects the coolant distribution in the leading edge film holes. A decrease in installation angle increases the coolant flow rate on the suction side of the leading edge, thus increasing the non-uniformity of coolant distribution. However, increasing the Mass flow ratio can mitigate this effect. Among the three proposed improved cooling schemes, it was found that reducing the hole inclination angle and changing the film hole layout significantly improved the film cooling effectiveness and the consistency of the cooling effect. The cooling scheme that adjusted the hole inclination angle resulted in a maximum increase of 62.5 % in film cooling effectiveness (η), while the cooling scheme that modified the hole layout reduced maximum variation in film cooling effectiveness (Δη_max) by 43.9 %.