高速条件下吸力面复合角孔气膜冷却特性

Film cooling characteristics of compound angle hole on suction side under high-speed conditions

为探究高速条件下涡轮叶片吸力面上复合角孔的气膜冷却特性,在高速风洞中实验测量了吸力面复合角孔的气膜冷却效率与传热系数比,并通过净热通量减少(NHFR)衡量了复合角孔对吸力面的气膜冷却净收益。分析了雷诺数、吹风比以及湍流度对气膜冷却效率、传热系数比及净热通量减少的影响规律,结果表明:低雷诺数下气膜冷却效率受雷诺数影响较大,但当雷诺数增大至6.4×10^(5)以上时,气膜冷却效率几乎不再变化;随湍流度的增大,气膜冷却效率整体降低,低吹风比下气膜冷效对雷诺数、湍流度较为敏感。传热系数比随气膜吹风比增加而增大,但在湍流度较大时,气膜冷却对传热系数的影响降低。湍流度的增大使NHFR有所升高。研究表明对高的湍流度工况,吹风比为0.8时复合角孔呈现最佳的气膜冷却性能。

To investigate the film cooling characteristics of compound angle holes on turbine vane under high-speed conditions,a row of compound angle holes were set up on the suction surface of the turbine vane.The film cooling effectiveness and heat transfer coefficient ratio of the compound angle holes were measured.And the net gain of film cooling was measured by net heat flux reduction(NHFR).The effects of Reynolds number,blowing ratio and turbulence intensity on the film cooling effectiveness,heat transfer coefficient ratio and net heat flux reduction were analyzed.It was found that the film cooling effectiveness was affected by the Reynolds number,but when Reynolds number was larger than 6.4×10^(5),the film cooling effectiveness almost didn’t change with Reynolds number any more.When the turbulence intensity increased,the film cooling effectiveness decreased,making it more sensitive to the turbulence intensity at a low blowing ratio.The heat transfer coefficient ratio increased with the blowing ratio,but its sensitivity decreased under higher turbulence intensity.When the turbulence intensity increased,NHFR also increased.In general,at the blowing ratio is 0.8,the compound angle hole presents the best film cooling performance at a higher turbulence intensity.