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

Effects of Area Ratio of Film Hole to Impingement Hole and Momentum Flux Ratio on Overall Cooling Effectiveness of Afterburner Double Wall Heat Shield

关键词:  加力燃烧室  隔热屏  冲击发散冷却  面积比  综合冷却效率

Key words:  Afterburner  Heat shield  Impingement/effusion cooling  Area ratio  Overall cooling effectiveness

摘要:

利用冲击/发散双层壁冷却结构可以有效加强冷却效果。针对加力燃烧室隔热屏高效冷却性能的发展要求，基于综合冷却效率模化理论和匹配原则，采用红外测温技术测量了加力燃烧室双层壁隔热屏的综合冷却效率分布，分析了气膜孔与冲击孔面积比（Af/Ai=1，2，3，4）和动量比（I=0.02~0.88）等参数对加力燃烧室双层壁隔热屏冷却特性的影响规律。研究结果表明：综合冷却效率分布由冲击冷却、气膜冷却及冲击孔和气膜孔的相对位置决定。高冷效区域集中在冲击驻点附近和气膜覆盖的区域。沿着主流的流动方向，气膜板下游的综合冷却效率高于上游的综合冷却效率。随着动量比的增大，综合冷却效率增大。随着气膜孔与冲击孔面积比的增大，气膜板上游的综合冷却效率主要是由于冲击换热的增强而增大，气膜板中下游的综合冷却效率是由于冲击换热和气膜冷却效果的增强而增大。气膜孔与冲击孔面积比由1增大到3，面平均综合冷却效率提高72%，气膜孔与冲击孔面积比由3增大到4时，面平均综合冷却效率提高了12%。

Abstract:

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 （Af/Ai=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.