主流湍流度对涡轮导向叶片气膜冷却特性影响的实验

采用基于窄带热色液晶的瞬态全表面传热测量技术,研究了主流湍流度对涡轮导向叶片吸力面圆柱形孔排气膜冷却特性的影响规律.结果表明:在实验工况范围内,主流湍流度从0.59%提高至6.85%,可以在气膜出流的上游区域促进气膜贴向壁面并扩大展向覆盖面积,从而改善气膜覆盖效果,但是在主流湍流度较大的工况下,气膜覆盖效果迅速变差;在气膜出流的下游区域,主流湍流度的提高使得气膜冷却效率逐渐降低;主流湍流度的增大,增强了无气膜冷却光滑叶片表面的对流换热;在气膜冷却条件下,气膜出流对叶片表面对流换热的增强效果随着主流湍流度的增大呈现出明显的区域性特点:表面传热系数比在上游区域是先增强后减弱;中游区域是逐渐减弱;下游区域则是逐渐增强.

Experiment on effects of mainstream turbulence intensity on film cooling characteristics of turbine vane

The effect rules of mainstream turbulence intensity on film cooling characteristics of cylindrical holes on the suction side of turbine vane were studied using the transient heat transfer measurement technique with narrow-band thermochromic liquid crystal in the whole region. The results show that the mainstream turbulence intensity increase from 0.59% to 6.85% in experimental conditions can make film sticking the wall and expand the lateral coverage area in the upstream region to improve the film coverage performance. But when the mainstream turbulence intensity is very large, the film cooling performance will rapidly deteriorate. In the downstream region of film injection, film cooling efficiency decreases gradually with the mainstream turbulence intensity increasing. Heat transfer on the smooth vane surface without film cooling can be enhanced by increasing the mainstream turbulence intensity. Under the conditions with film cooling, the effects of the heat transfer enhancement of vane surface caused by the film injection have distinctive regional characteristics with the mainstream turbulence intensity increasing. The heat transfer coefficient ratio firstly increases and then decreases in the upstream region, gradually decreases in the midstream region, and slightly increases in the downstream region.