气膜孔与冲击孔面积比和动量比对加力燃烧室双层壁隔热屏综合冷却效率的影响

The cooling effect can be effectively enhanced by using the impingement/effusion double wall cooling structure. According to the developing requirements of high efficient cooling performance of afterburner heat shield, based on analogy theory and matching principle for scaling overall cooling effectiveness, the overall cooling effectiveness distribution of afterburner double-wall heat shield were measured by using IR thermography. Effects of area ratios of film hole to impingement hole (A_f/A_i=1, 2, 3, 4) and momentum flux ratios (I=0.02~0.88) on the cooling characteristics were investigated experimentally. The results indicate that the overall cooling effectiveness distribution is determined by the impingement cooling, the film cooling, and the relative position of impingement hole and film hole. High overall cooling effectiveness appears in the region near the impingement stagnation point and covered by the film. Along the streamwise direction, the overall cooling effectiveness in the downstream region of film plate is higher than that in the upstream region. As the momentum flux ratio increases, the overall cooling effectiveness increases. With the increase of the area ratio of film hole to impingement hole, the overall cooling effectiveness in the upstream region of film plate mainly increased due to the enhancement of the impingement heat transfer, and the overall cooling effectiveness in the middle and downstream region of film plate increased due to the enhancement of impingement heat transfer and the film cooling effect. The area averaged overall cooling effectiveness increased by 72% with increasing the area ratio of film hole to impingement hole from 1 to 3, and the area averaged overall cooling effectiveness increased by 12% with increasing the area ratio of film hole to impingement hole from 3 to 4.