孔排布局对叶片前缘气膜冷却的影响

 采用放大的半圆柱状表面模拟涡轮叶片前缘的形状,对叶片前缘单排及两排圆柱形孔的气膜冷却效率进行了测量。试件表面交错地开有 6排孔,以驻点为起点,位置分别在± 1 5°,± 4 0°及± 60°处,各排孔的孔间距均为 3个孔径,孔轴线与表面在展向及流向的夹角分别为 30°及 90°,孔长与孔径比为 4。主要对比研究了 3种单排气膜孔不同孔排位、3种两排气膜孔不同孔排位及 1种三排气膜孔的布局对孔排下游冷却效率的影响。结果表明 :在同样二次流流量条件下,冷却效果好的单排孔位置依次为 60°,4 0°,1 5°,冷却效果最好的两排孔位置组合为 ( 40°,60°)。结果还表明 :在较大的二次流流量条件下,采用单排孔、两排孔或三排孔冷却方案对孔排下游的冷却效果影响不大;但在较小的二次流流量条件下,从冷却效果看,较好的孔排冷却方案依次为 :三排孔、两排孔及单排孔。实验参数范围是 :主流雷诺数 Re=4 2 0 0 0～ 1 2 70 0 0,平均吹风比 M =0.5～ 2.0

INFLUENCES OF POSITION OF HOLE-ROWS ON FILM COOLING ON LEADING EDGE OF TURBINE BLADE

Film cooling effectiveness of hole rows on leading edge of turbine blade has been studied experimentally. The model is a blunt body with a half cylinder leading edge with two flat side walls. Six rows of round holes were ungradatedly located at ±15°,±40° and ±60° from stagnation on the half cylinder leading edge. The holes in each row were spaced three hole diameters apart and were angled 30° and 90° to the surface in the spanwise and streamwise directions respectively. The length of hole is four hole diameters. The focus of this paper is the influences of holes row position on film cooling effectiveness on leading edge of turbine blade. Measurement was carried out for mainstream Reynolds number (based on leading edge diameter) from 42000 to 127000 and blowing ratio (average secondary to mainstream mass flux ratio) from 0.5 to 2.0. The results show that the better position of single holes row ordinally is 60°, 40°and 15°, and that the better position of double holes row is (40°,60°). The results also show that there is no difference in using single or double or three film cooling holes row with larger secondary flow flux, and that the better film cooling effect with smaller secondary flow flux can be taken in using three film cooling holes row.