渐扩后倾肩臂孔平板气膜冷却特性实验研究

Experimental research of the plate film cooling characteristics of backward-expanding shoulder arm hole

提出一种新型气膜冷却孔型——渐扩后倾肩臂孔,运用压力敏感漆(PSP)实验技术,研究其与圆孔、肩臂孔的气膜冷却性能差异,并采用N2和CO2气体作为冷却气,对比分析了密度比1.0和1.5情况下吹风比(Br=0.5～2.0)对渐扩后倾肩臂孔平板气膜冷却性能的影响。结果表明:在相同密度比、吹风比条件下,渐扩后倾肩臂孔方案冷却效率优于圆孔和肩臂孔(肩臂孔略高于圆孔)。在密度比为1.0的情况下,当测量点离孔的距离与孔入口直径的比值x/D<15时,渐扩后倾肩臂孔方案的展向平均气膜冷却效率随着吹风比的增大呈递减趋势;当x/D>15时,冷却效率在Br=1.0时最大。在密度比为1.5的情况下,渐扩后倾肩臂孔方案的展向平均气膜冷却效率随着吹风比的增大呈先增大后减小的趋势,在Br=1.0时冷却效率最大。分析认为:不同密度比情况下,吹风比对渐扩后倾肩臂孔冷却性能的影响差异,主要是由于密度比较小时,冷却气出口速度更大,使冷却气更易吹离冷却壁面。

A new turbine film-cooling hole shape that is named the backward-expanding shoulder arm hole is designed.By using N 2 and CO 2 gas as the cooling gas,the film cooling perfor-mance with different density ratios of the backward-expanding shoulder arm hole,the circular hole and the shoulder arm hole is studied in the paper.The results show that,under the same conditions the film cooling efficiency of the backward-expanding shoulder arm hole is better than that of the circular hole and the shoulder arm hole,and the film cooling efficiency of the shoulder arm hole is slightly higher than that of the circular hole.The average film cooling efficiency decreases with the increase of the blowing ratio in the place where x/D<15,and the average film cooling efficiency at Br=1.0 reaches maximum in the place where x/D>15 when the density ratio is 1.0.The average film cooling efficiency increases first and then decreases with the increase of the blowing ratio,and the average film cooling efficiency is highest at Br=1.0 is maximum.The analysis indicates that as the outlet velocity is higher when the density is lower under the same blowing ratio,so that the cooling gas is more easily blown away from the cooling wall,the blow-ing ratio has effects on the film cooling efficiency of the backward-expanding shoulder arm hole.