凹槽叶顶的气膜冷却特性

Film cooling characteristics of squealer tip of a turbine blade

涡轮工作时,叶顶间隙内高速高温的间隙泄露流会直接冲刷动叶顶部,产生局部高温区域,因此控制间隙泄露流至关重要。基于压敏漆涂料(PSP)实验,研究了密度比、吹风比和间隙高度对凹槽叶顶气膜冷却特性的影响。研究结果表明:密度比增大,凹槽叶顶气膜冷却效果逐渐提高,尤其是大间隙下冷效提高较为明显,叶顶面平均冷效增加了35%;间隙高度和吹风比对叶顶表面冷效的作用不是单一的,小间隙条件下,叶顶表面气膜冷效随着吹风比增大而增大,大间隙条件下,吹风比的增加使得叶顶表面气膜冷效先减小后增加,同时小吹风比时,间隙高度增加提高了叶顶尾缘区域和孔周围的气膜冷效,叶顶面平均冷效提高了6.85%。

The high-speed and high-temperature gap leakage flow in the turbine blade tip clearance directly scours the tip of the rotor blade and generates a local high-temperature region,so the active and passive control of the gap leakage flow is very important.Based on the pressure sensitive paint(PSP)experiment,the effects of density ratio,blowing ratio,and clearance height on the film cooling characteristics of the squealer blade tip were studied.The results show that with the increase of the density ratio,the film-cooling effectiveness of the squealer blade tip gradually increases,especially in the large clearance height,and the average cooling effect of the blade tip is increased by 35%.The effect of tip clearance height and blowing ratio on the tip surface cooling effect is not single.Under the condition of small tip clearance,the tip surface film-cooling effectiveness increases with the increase of the blowing ratio.Under the condition of large tip clearance,the tip surface film-cooling effectiveness decreases first and then increases with the increase of blowing ratio.At the same time,when the blowing ratio is small,the increase in tip clearance height improves the tip trailing edge area and the film-cooling effectiveness around the holes,and the average cooling effect of the blade tip surface increases by 6.85%.