Experimental study of film cooling characteristics for dust-pan shaped holes on suction side in turbine guide vane

In order to investigate the film cooling characteristics on suction side of a turbine guide vane, the film cooling effectiveness for two single rows of dust-pan holes was measured experimentally using transient method in a transonic cascade heat transfer wind tunnel, and the effects of several flow parameters on its distribution were analyzed. The two rows of holes are located at 6.8%, 21.7% relative arc, respectively. The range of inlet Reynolds number based on vane chord length is 1.7×10⁵~5.7×10⁵, the range of exit isentropic Mach number is 0.81~1.01 and the blowing ratio changes from 0.6 to 2.1, which cover the typical working states of turbine guide vane. The results show that, the optimum blowing ratio is around 0.9~1.2 for dust-pan shaped holes at the condition of designed Reynolds number, and the jet from Hole 2 near the leading edge attaches better than Hole 1. The effect of mainstream Mach number on cooling effectiveness after the hole can be neglected. The effectiveness of low Reynolds number cases is lower than that of moderate or high Reynolds number cases. The dust-pan shaped holes perform better than the cylinder holes, especially at moderate and high blowing ratio cases of BR>1.5. At low blowing ratios, film cooling is more effective on the convex surface than on a flat surface especially with the distance of s/d<20, while at high blowing ratios, the increased jet momentum promotes lift-off from the convex surface, thereby lowering the effectiveness.