温比对第一级导叶端壁气膜冷却特性的影响

利用高温风洞及远红外热像技术,在两种主燃气与冷气温比(TR)(1.64、2.68)和4种气膜注射吹风比(BR)(0.6、1.0、1.5、2.0)下,研究了导叶端壁十排复合角度圆形气膜孔的综合冷却效率。对比高、低温比下的实验结果发现:(1)在无气膜时,端壁前缘的最高温点会因主流温度的提高而更靠近叶片前缘;(2)气膜出流时,端壁近吸力面区域冷却效率高于近压力面区域,冷却效率随BR的提高而不断增大,且BR从1.0增加到1.5时,冷却效率增幅最明显;(3)在同一BR下,端壁的综合冷却效率会随TR的增加而提高,但随着BR的不断加大,TR对端壁平均冷却效率的影响逐渐减小,即:相比于TR为1.64下的面平均冷却效率,TR为2.68工况下的平均冷却效率在BR为0.5时可提高18.2%,而在BR为2.0时,其只相对提高了8.8%。

Effect of temperature ratio on film cooling characteristics at first-stage vane endwall

Experimental investigations of the film cooling characteristics at a vane end-wall with ten rows of compound film-holes were carried out in a hot wind tunnel using infrared thermograph technique. Two kinds of mainstream-to-coolant temperature ratio(TR) of 1.64 and 2.68, and four kinds of coolant-to-mainstream blowing ratio(BR) of 0.6, 1.0, 1.5 and 2.0 were chosen. Comparing the results at high and low TR, it revealed that: (1) in the case of no coolant injection, with the increase of mainstream temperature, the point of maximum temperature at the end-wall leading edge was pushed to vane leading edge; (2) in the case of coolant injections, the overall cooling effectiveness near suction side was higher than pressure side. The area-averaged cooling effectiveness increased with BR, moreover, the largest increment was generated from BR of 1.0 to 1.5; (3) the cooling effectiveness increased with TR at the same BR, but the extent of variation was reduced with the increasing BR, i.e. comparing with TR of 1.64, the area-averaged overall effectiveness can be enlarged by 18.2% at BR of 0.5, but by 8.8% at BR of 2.0.