Effect of Aerodynamic Parameters of Backward-Step Three Dimensional Slots on Film Cooling Effectiveness

According to the feature of the turbine blade trailing edge cooling,film cooling effectiveness of backward-step three dimensional slots injection was measured at the slot center line and rib center line.The effects of aerodynamic parameters on the film cooling effectiveness have been studied.The secondary flow Reynolds number based on slot height varied from 5 000 to 15 000 and blowing ratio changed from 0.5 to 2.0.The experimental results show that the influence of secondary flow Reynolds Number on film cooling effectiveness and three dimensional flow mixing region is unremarkable;the influence of blowing ratio on film cooling effectiveness,and the size and performance of the three dimensional mixing flow region is very significant.For lower blowing ratio,secondary flow will flow into mainstream region and the region behind the rib,this will benefit the protected wall;for high blowing ratio,the situation is the contrary.