亚声速涡轮导叶前缘气膜冷却特性实验研究

Experimental Investigation of Leading Edge Film Cooling Characteristics of Subsonic Turbine Guide Vane

为了获得亚声速涡轮导叶的前缘气膜冷却特性,在短周期高速风洞中对涡轮导叶前缘后倾扩张型孔气膜冷却试验件进行了实验,获得了涡轮叶片表面在不同主流雷诺数(Re=3.0×10~5～9.0×10~5)、二次流吹风比(M=0.5～2.4)和主流湍流度(Tu=1.3%,14.7%)下的气膜冷却效率和换热系数分布。实验叶片前缘有8排后倾扩张型气膜孔形成前缘喷淋冷却结构。结果表明:叶片前缘和压力面冷却效率随着吹风比的增大而升高,吸力面冷却效率随着吹风比的增大先升高后降低,最佳吹风比为0.8;在主流雷诺数(Re=3.0×10~5～9.0×105),改变雷诺数对叶片表面冷却效率的分布规律影响较小;叶片表面冷却效率随着湍流度的升高而降低,在小吹风比M=0.5下,高主流湍流度下的平均冷却效率降低50%左右,在M=2.4工况下,高湍流度下的平均冷却效率降低10%左右;叶片前缘冷气出流区域和压力面相对弧长为-0.4<S/Smax<-0.3的冷气重新贴附壁面区域换热系数比较高;高主流湍流度下,换热系数比较小,且吹风比变化对换热系数比的影响较小。

In order to study the leading edge film cooling characteristics of subsonic turbine guide vane,the film cooling effectiveness and heat transfer coefficient of leading edge film cooling turbine vane in different mainstream inlet Reynolds number(Re=3.0×105~9.0×105),second flow blowing ratio(M=0.5 ~2.4) and mainstream turbulence intensity(Tu=1.3%, 14.7%) conditions were measured in short-duration high speed wind tunnel. There are 8 laid-back shaped hole rows on the leading edge to obtain a showerhead film cooling. The results show that in the range of blowing ratios studied in the present paper, the film cooling effectiveness on leading edge and pressure side increases with blowing ratio increasing, while the film cooling effectiveness on the suction side increases and decreases with blowing ratio increasing, the optimum blowing ratio is 0.8. In the range of Re=3.0×105~9.0×10-5 the change of mainstream inlet Reynolds number has little effect on film cooling effectiveness distribution. The film cooling effectiveness decreases with turbulence intensity increasing, the average film cooling effectiveness at high mainstream turbulence intensity decreases around 50% in M=0.5 condition, while it decreases around 10% in M=2.4 condition;the heat transfer coefficient ratio on the leading edge and the coolant reattachment region of relative arc-0.4<5/Smax<-0.3 on pressure side is high. In high mainstream turbulence intensity condition, the heat transfer coefficient ratio is lower and the effects of blowing ratio on the heat transfer coefficient ratio are smaller.