全气膜冷却叶片表面换热系数和冷却效率研究

为了研究全气膜冷却涡轮导叶叶片的换热特性,采用瞬态液晶技术获得了叶片全表面的高分辨率换热系数和冷却效率.实验在三叶片两通道放大模型中完成,叶栅进口雷诺数是1.0×105. 叶片前缘有8排复合角孔,压力面有21排轴向角孔,吸力面有24排轴向角孔.气膜孔排由2个供气腔供气,前腔二次流与主流的质量流量比为4.56％,后腔为4.67％.结果表明:受叶栅通道涡作用,气膜出流在吸力面呈聚敛状,在压力面则呈发散状.气膜出流受气膜孔角度影响,气膜孔下游的换热系数和冷却效率都较高.叶片前缘受到冲击,换热强,冷却效率低；叶片吸力面冷却效率维持在0.4左右,压力面维持在0.35左右.该全气膜冷却叶片气膜覆盖效果较好,冷却效率和换热系数分布均匀,是一种较好的冷却结构.

Heat Transfer Coefficient and Film Cooling Effectiveness on a Full-Film Cooling Vane

The high-resolution heat transfer coefficient and the film effectiveness measurements on a full-film cooling nozzle guide vane with compound and axial angle holes were obtained using a transient liquid crystal technique.The tests were performed in a scaled-up,two-passage cascade at an inlet Reynolds number of 1.0×105.There are eight rows of compound angle cylinder film holes around the leading edge,21 rows of axial angle cylinder holes on the pressure side,and 24 rows of axial angle cylinder holes on the suction side.The holes are fed from two internal plenum with a mass flow ratio of 4.56% in the first plenum and 4.67% in the second plenum.The results show that the film cover region shrinks on the suction side and expands on the pressure side due to the influence of passage vortex.The heat transfer coefficient and the film cooling effectiveness are higher in the near hole region.The heat transfer coefficient is higher and the film cooling effectiveness is lower near the leading edge.The film cooling effectiveness is about 0.4 on the suction side and about 0.35 on the pressure side,respectively.