Experimental Study on the Effects of Slot Jet on Film Cooling Performance in the Cascade Endwall With Purge Flow

Abstract Based on the infrared temperature measurement technology, in this paper, the effect of the purge flow from the upstream slot on the film cooling performance of the annular cascade endwall was studied experimentally. GE‘s E3 turbine first stage stator blades is selected as the experimental reference blade type in this experiment. In the current experiment, effects of different slot locations, slot ejection angles and slot profiles on the endwall film cooling effectiveness were taken into account. Under the influence of endwall secondary flow, the film cooling is mainly concentrated on the front part of the channel and close to the suction side of the blade, while there is almost no cooling effect close to the pressure side of the blade in the channel. With the increase of the distance between the blade leading edge and the slot, the endwall film cooling performance is reduced. While the distance increasing from 0.15Cx to 0.45Cx, and the peak endwall film cooling effectiveness is reduced by 78%, 68% and 58% respectively when the mass flow ratio (MFR) is 1.0%, 1.5%, and 2.0%. As the slot ejection angle is reduced, the endwall film cooling performance can be effectively improved. When the slot ejection angle increased from 45° to 90°, the peak endwall film cooling effectiveness decreases by 17%, 15%, and 13% respectively at the mass flow ratio (MFR) = 1.0%,1.5% and 2.0%. And the convergent slot can effectively improve the endwall cooling film formed by slot jet compared to the reference slot. When the mass flow ratio are MFR = 1.0%, 1.5%, and 2.0%, the peak endwall film cooling effectiveness at the convergent slot is increased by 50%, 20%, and 15% comparing to the reference slot.