涡轮叶片上收缩-扩张形孔排的全表面气膜冷却特性

为了摸清新型收缩-扩张形孔在涡轮叶片上的气膜冷却特性,采用一种可进行全表面测量的稳态液晶测量技术测量了收缩-扩张形孔排在涡轮叶片模型上的气膜冷却效率分布。研究了基于叶片弦长的主流雷诺数和二次流-主流流量比对冷却效率的影响,并与叶片上圆柱形孔排的气膜冷却效率分布进行了对比。结果表明:受叶栅通道涡作用,两种孔排的射流轨迹在吸力面呈聚敛状;在压力面则呈发散状;但通道涡对收缩-扩张形孔排射流的影响较弱。收缩-扩张形孔排在吸力面和压力面上的气膜覆盖范围和冷却效率都远大于圆柱形孔排,而且收缩-扩张形孔排的冷却效率随流量比的增大而增大;在压力面上,叶片型面结构使得收缩-扩张形孔排以及圆柱形孔排的气膜覆盖效果好于吸力面。在本文的实验雷诺数范围内,主流雷诺数对收缩-扩张形孔排的冷却效率分布特征以及冷却效率数值大小的影响都很小。

Experimental Research on Film Cooling Characteristics of Converging-expanding Hole Rows on Turbine Blade Surface

The film cooling effectiveness distributions of converging-expanding hole rows on the turbine blade model are measured using a steady liquid crystal measurement technique. The influences of Re based on the blade chord length and coolant-gas flux ratio are tested, and comparison is made between the effect of the converging-expanding hole rows and cylindrical hole rows. The results show that the jet trace is converging on the suction side and expanding on the pressure side for both converging-expanding hole rows and cylindrical hole rows owing to the influence of the passage vortex system. However, compared to the cylindrical hole rows, the influence of the passage vortex on the jets of converging-expanding hole rows is weaker, and the film covering area and the film cooling effectiveness of converging-expanding hole rows are much larger on both the suction and pressure sides. The film cooling effectiveness of converging-expanding hole rows increases with the increase of the coolant-gas flux ratio, increasing, and the film cooling performance on the pressure side is better than that on the suction side for both kinds of hole rows because of the concave surface. The influence of Re on cooling effectiveness distribution and the cooling effectiveness value of the converging-expanding hole rows is nearly negligible on both the suction and pressure sides in the range of the current test conditions.