静叶栅上游端壁双射流气膜冷却特性实验

Experimental study of film-cooling characteristics of DJFC holes located upstream of a vane

为了进一步挖掘上游端壁气膜冷却的潜力,在低速叶栅风洞的静叶片上游端壁上,实验研究了双射流构型的气膜冷却特性,并与双排圆孔进行了对比。探究了吹风比(M=0.5,1.0,1.5,2.0)、密度比(Rd=1.0,1.5)的效应。端壁表面的气膜冷却效率通过压力敏感漆(PSP)测得。结果表明,吹风比的增大虽然会加剧吹离现象,但同时也会促进叶栅通道中、后段的气膜覆盖。密度比的增大会抑制气膜吹离,促进气膜横向覆盖和提高平均冷却效率。双射流孔相比于圆形孔,冷却气流在孔下游形成了反肾形涡,较好抑制了气膜吹离;但从双射流孔喷出的冷却气流对于叶栅通道内的涡系也更加敏感。在高吹风比下,双射流孔的冷却效率相对于圆形孔有一定的优势,特别是双射流I构型。

To further explore the potential of film-cooling on the upstream endwall,the film-cooling characteristics of DJFC(double-jet film-cooling)holes on the endwall upstream of a vane cascade was studied by experiments and corresponding results were compared with double-row streamwise cylindrical holes located in the same position.Effects of blowing ratio and density ratio were discussed.PSP(pressure sensitive paint)was applied to measure film-cooling effectiveness on the endwall.Results show,though increased blowing ratio induces film lift-off,film coverage on the mid-and rear-portion of the endwall improves.Increased density ratio suppresses lift-off,enhances lateral coverage and increases lateral-average of effectiveness.Compared to SC(streamuise cylindrical)holes,anti-kidney vortices form at the exit of DJFC holes and thus decreases lift-off.However,DJFC holes are more sensitive to vortices generated in the cascade passage.At high blowing ratios,film effectiveness of DJFC holes are more advantageous over SC holes,especially DJFC I.