前缘喷淋射流对导叶压力面冷却特性的影响

Effect of showerhead injection of leading edge on cooling characteristics for turbine vane pressure side

为了评估涡轮导叶的前缘喷淋射流对压力面多排气膜孔冷却特性的影响,在高亚声速风洞中进行了实验,获得了有无前缘喷淋射流时叶片表面的气膜冷却效率和传热系数。叶栅进口雷诺数(基于叶片弦长)范围为2.0×10~5~4.0×10~5,出口等熵马赫数为0.95,叶片前缘和压力面分别都包含6排圆形孔,质量流量比的范围分别为2.46%~4.57%和2.00%~3.71%。实验结果表明:在没有前缘喷淋射流时,压力面前半段的气膜冷却效率受质量流量比的影响较小,而后半段的气膜冷却效率随着质量流量比升高而增大。前缘喷淋射流使压力面多排气膜孔的冷却效率提高了20%~70%,并且使气膜冷却效率沿流向分布更均匀。不论是否有前缘喷淋射流,压力面的传热系数比都随质量流量比升高而增大,沿流向看,前缘喷淋射流提高了压力面前缘和尾缘区域的传热系数比而对压力面中间区域影响较小。

In order to evaluate the effect of showerhead injection of leading edge on the cooling characteristics of turbine vane pressure side with multirow film holes,an experiment was carried out in a high subsonic wind tunnel to obtain the film cooling effectiveness and heat transfer coefficient on the vane surface with/without showerhead injection of leading edge.The inlet Reynolds number of the cascade(based on the true chord length of the vane)varied from 2.0×10~5 to 4.0×10~5,the exit isentropic Mach number was 0.95.Six rows of cylinder holes were arranged on the leading edge and the range of mass flow ratio was 2.46%-4.57%,the pressure side was assigned with 6 rows of cylinder holes and the mass flow ratio varied from 2.00%to 3.71%.The experimental results showed that without showerhead injection of leading edge,the film cooling effectiveness on the front half of the pressure side was less affected by mass flow ratio,however,that on the rear half increased with the increase of mass flow ratio.The showerhead injection of leading edge raised the film cooling effectiveness of pressure side with multi-row holes by 20%~70%,and made the distribution of film cooling effectiveness more uniform along the flow direction.No matter whether the showerhead injection of leading edge existed,the heat transfer coefficient ratio on the pressure side increased with the mass flow ratio increasing.Viewed from streamwise,the showerhead injection of leading edge increased the heat transfer coefficient ratio in the region of leading and trailing edges on the pressure side,however,exerted a little effect in the middle region of pressure side.