Failure Mechanism of Combustion Chamber of Liquid Rocket Engine under Severe Multi-Physics Conditions (Residual Deformation of Chamber Throat)

In developing liquid rocket engine, life time of combustion chamber is an important design issue. However, it is very difficult to quantitatively predict the life time because complicated multi-physics phenomena occur under severe conditions in the combustion chamber. The LE-X engine is under study in JAXA as the next booster engine. In its research and development, shorter development time, lower cost and higher reliability are sought by using front-loading design approaches. Therefore, it is indispensable to evaluate the life time of the combustion chamber precisely in the early phase of development. In order to improve accuracy in the life prediction, we focus on the interaction between thermo-fluid behaviors and structural responses, and have developed a new analysis procedure, that is, high-fidelity multi-physics coupled simulation. By applying this procedure, we have investigated the mechanisms and the dominant factors of residual deformation occurred in the throat, which was experienced under development of the upper stage engine. It has been revealed that the throat's residual deformation strongly depends on cooling capability in the shutdown process, which is affected by the transient flows of both combustion gas and coolant.