带单排气膜孔导向叶片前缘气膜冷却实验研究

Film Cooling of Leading Edge on the Vane with a Row of CO_2 Injection Holes

针对导向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2个平板组成,在距离滞止线2倍气膜孔直径位置布置了1排气膜孔。详细地测量了动量比对前缘径向平均换热系数和冷却效率的影响。二次流与主流密度比为1.5。动量比变化范围为0.5-4。主流在前缘位置的湍流度为0.4%和8%。研究结果表明,随着动量比的增加,换热系数增加,冷却效率减小。低动量比时气膜冷却使热负荷减少,高动量比时气膜冷却使热负荷增加。

Purpose. Refs. 1 to 4 applied air as second flow to obtain a density ratio of 1, we apply CO2 as second flow to obtain a density ratio of about 1.5 so as to be closer to the real situation in an engine. In the full paper, we explain in detail two things： （1） how to carry out such an experiment; （2） what the experimental results are. In the abstract, we first explain how to carry out such an experiment： The model is blunt body with a half cylinder leading edge and two flat plates. One row of holes is located at two hole diameters from the stagnation line of the leading edge. CO2 is used to obtain a density of approximately 1.5. High turbulence intensity is produced by a passive grid. Momentum flux ratios varies from 0. 5 to 4. The thermocouples are used to measure the temperature of the surface. Then, we give the experimental results and their corresponding analysis presented as Nu/Re^0.5, cooling effectiveness and heat load. On the basis of the experimental result and analysis, we give the following three conclusions： （1） Nu/Re^0.5 with film cooling is much greater than that without film cooling. Nu/Re^0.5Sincreases with the increase of momentum flux ratios in the case of film cooling. （2） Cooling effectiveness decreases with the increase of momentum flux ratios. Along the mainstream flow direction, cooling effectiveness first increases and then decreases. （3） Heat load reduces when the low momentum flux ratios are low and increases when the momentum flux ratios are high.