An Experimental Study of Cooling Film in Negatively Bowed Cascade with Large Turning Angle

Transverse measurements are carried out at the outlet of the straight and negatively bowed turbine cascades with 106° turning angle respectively with and without cooling air injection from holes of the ten rows and from holes of several rows of the ten rows (totally 26 schemes).Experimental results show that negatively bowed cascade produces more energy loss than the straight one without cooling air injection.Cooling air injection from the holes on the pressure surface and from the holes on the suction surface near the trailing edge can reduce energy losses in both the straight and the negatively bowed cascades.The increase in loss is less in negatively bowed cascade than that in the straight one with cooling air injection from holes of several rows at the leading edge,whereas cooling air injection from holes of several rows at the trailing edge reduces the energy loss in the negatively bowed cascade.