某氢氧发动机推力室氢喷嘴烧蚀问题仿真分析

Simulation analysis of hydrogen nozzle ablation problem existing in thrust chamber of a hydrogen oxygen engine

氢氧火箭发动机推力室内的喷注均匀性不但影响燃烧效率,还有可能影响喷嘴、面板及内壁等结构的可靠性。针对某型氢氧火箭发动机推力室多次出现固定位置两个氢喷嘴的烧蚀问题,采用CFD方法模拟了此发动机氢头腔及喷嘴的内部流动。通过分析流动特性,并给出量化对比结果,得出了以下两个结论:一方面此发动机推力室喷注面氢流量分布不均,而多次产生烧蚀的喷嘴是所有喷嘴中氢流量最小的两个;另一方面氢喷嘴出口环形间隙内流量分布不均,在所有喷嘴中产生烧蚀的喷嘴出口流速分布不均匀度是最高的。这两个因素共同作用下导致喷嘴局部混合比过高,是造成固定位置喷嘴局部烧蚀的重要原因。

The injection uniformity in thrust chamber of hydrogen oxygen rocket engine not only affects the combustion efficiency, but also may affect the reliability of nozzle, panel and inner wall structure. Aiming at the phenomenon that two hydrogen nozzles at a fixed position of a certain hydrogen oxygen rocket engine were ablated repeatedly, CFD method is used to simulate the inner flow of hydrogen head chamber and nozzle of this engine. Two conclusions for the ablation phenomenon were obtained on the basis of analysis of flow characteristics and quantized contrast of the results. The first conclusion is that the hydrogen flow distribution is uneven in the thrust chamber and the ablated nozzles have smallest hydrogen flow among all the nozzles. The second conclusion is that there is uneven flow distribution in the annular space at outlet of hydrogen nozzle, and the ablated nozzles have highest unevenness of velocity distribution at their outlets. The combined action of these two factors can cause that the local mixing ratio of the two nozzles is too high, which is the important reason that the local ablation has occurred to the nozzles at the fixed position in the thrust chamber.