涡轮流场影响端壁气膜冷却的实验研究

Experimental Investigation on the Turbine Blade Platform Film Cooling Effected by the Flow Field

采用压力敏感漆技术对高压涡轮动叶平面叶栅端壁气膜冷却特性进行了实验研究,对比分析了气膜冷却射流吹风比和叶栅进口主流雷诺数对端壁气膜有效度分布的影响。实验中主流雷诺数分别为164476、226154、308392和359790,各主流雷诺数下气膜射流吹风比变化范围从0.4到1.4。端壁前缘气膜孔吹气角为45°,其余端壁气膜孔吹气角为30°。实验结果表明:端壁后段气膜冷却效果随吹风比的增加而加强,气膜附面特性良好;前缘气膜冷却效果随吹风比的增加逐渐减弱,气膜出现明显吹离现象;当雷诺数为164476、226154、308392和359790时,端壁气膜冷却最佳射流吹风比分别对应为1.2、1.4、1.4和1.4;当雷诺数为359790时端壁气膜冷却在各射流吹风比下均有最佳效果。

An experimental investigation has been completed using PSP technique to study film cooling on a cooled turbine blade platform within a linear cascade.The effects of blowing ratio and inlet flow Reynolds number have been investigated and analyzed.The inlet flow Reynolds number is controlled to be Re=164476,226154,308392 and 359790,while the blowing ratio of the coolant varies from M=0.4 to 1.4.The film cooling holes near the platform leading edge are inclined 45°to the platform surface and the rest are 30°.The result indicates that the film cooling effectiveness increases with the blowing ratio increasing,which is limited to the downstream half of the passage where the platform can be well protected by the coolant flow.In contrast,the film cooling effectiveness is reduced by increasing the blowing ratio near the leading edge region where the coolant tends to lift off the surface.The most effective blowing ratios at different inlet Reynolds number Re=164476, 226154,308392,359790 are M=1.2,1.4,1.4 and 1.4 respectively.When the blowing ratio is fixed,the best coolant coverage occurs at the largest inlet flow Reynolds number Re=359790.