关键词: 甲烷;液体火箭发动机;再生冷却;推力室;热分析;结构分析;有限元法

Abstract: To study the structural deformation of the thrust chamber for a liquid oxygen/methane engine under multi-cycle working conditions， a thermo-structural analysis method including fluid-thermal analysis and nonlinear finite element analysis was developed and verified. The thermal and pressure loads on the thrust chamber were obtained by this method， and the stress-strain responses of the thrust chamber under these loads were also investigated. The results show that the overall deformation of the thrust chamber structure is not mainly determined by thermal loads， and the bending of the cooling channel bottom caused by pressure loads is particularly evident in the divergent segment of the nozzle. The elastoplastic tensile strain generated in the post-cooling phase was greater than the compressive strain generated in the hot run phase， which is the direct cause of structural residual strain after each working cycle. As the increasing of the working cycle number， the residual strain accumulation rate at the bottom corner of the cooling channel in the divergent segment was the fastest， and this location was identified as potential location of structural failure. Increasing the bottom thickness of the cooling channel near the coolant inlet， reducing the temperature difference between the post-cooling and the hot run phase， and designing the sharp bottom corners of cooling channels into rounded corners could be the alternative measures to suppress deformation and slow down strain accumulation.

Key words: Methane;Liquid rocket engine;Regenerative cooling;Thrust chamber;Thermal analysis;Structural analysis;Finite element method