带单排气膜孔的叶片前缘气膜冷却换热实验

Experimental investigation of leading edge film cooling heat transfer with a row of film cooling holes

关键词:  航空发动机  涡轮叶片  薄膜冷却  传热  实验

Key words:  Aircraft engine  Turbine blade  Film cooling  Heat transfer  Experimentation

摘要:

针对叶片前缘结构的特点,建立了前缘气膜冷却实验台,实验模型由半圆柱面和两个平板组成,在距离滞止线2倍孔间距位置布置了1排气膜孔。详细地测量了主流湍流度,二次流与主流密度比以及动量比对前缘径向平均换热系数和换热系数比的影响。二次流与主流密度比为1和1.5。动量比变化范围为0.5~4。主流在前缘位置的湍流度分别为0.4%和8%。结果表明,随着动量比的增加,径向平均换热系数增加。无二次流时,湍流度的增加使换热显著增强,有二次流时,湍流度增加使换热增强的幅度较小。密度比对径向平均换热系数的影响非常小。随着孔间距的增加,径向平均换热系数略有减小。径向角对径向平均换热系数的影响较小。在高湍流度下,前缘位置的径向平均换热系数比沿着流动方向是逐渐降低的。在低湍流度下,前缘位置的径向平均换热系数比在x/d=4.5的位置出现了一个峰值。

Abstract:

Heat transfer coefficient on leading edge with one row of holes was a studied experimentally.The model was a blunt body with a half cylinder leading edge and two flat plates.One row of holes was located at 2 hole diameter away from the stagnation line.Foreign gas injection was used to obtain a density of approximately 1.5.High turbulence intensity was produced by a passive grid.Momentum ratios were varied from 0.5 to 4 for both air and CO2 injections.The results indicate that heat transfer coefficients increase with increasing momentum flux ratio.High turbulence has pronounced influence on the heat transfer without secondary injection,but this effect is very weak with secondary injection.Various density ratios have little influence on heat transfer.In the case of high turbulence,heat transfer coefficients decreases along the flow direction and in the case of low turbulence and peak enhanced factor occurs at the x/d=4.5.