液氧/煤油高压推力室液膜冷却环局部过热分析

Investigation on local overheating of the film cooling ring for LOX/kerosene high pressure chamber

液氧/煤油发动机高压推力室采用了多条液膜冷却环带技术。由于室压高和热流密度大,易出现冷却环带结构局部过热现象,局部过热(甚至局部烧蚀)有时发生在燃烧室收缩段的冷却环上沿。传热计算和对比分析表明,在降低边区混合比的同时,第一冷却环带流量增大25%,可使过热处气壁温下降约35℃。采取增加冷却环带流量、降低燃烧室边区混合比、改善液膜冷却局部喷注结构等措施有利于燃烧室壁面的热防护,可防止局部过热的发生。

The multi-ring film cooling technique was introduced for thermal protection of the high pressure chamber of LOX/kerosene engine. The local overheating （even ablation） of the film cooling structure occurred ocassionally at the slot step （aft lip） due to the high chamber pressure with large heat flux. The comparison analysis of heat transfer calculation was conducted, and the results show that the hot-gas side wall temperature can reduce about 35 ℃ by increasing the flow rate by 25% and a lower peripheral mixture ratio. The measures of increasing film cooling flow rate, decreasing peripheral mixture ratio and improving the local film ring structure are effective for chamber wall thermal protection and preventing local overheating or ablation.