Analysis On Strength Of The Solid Rocket Engine Structure And Regressive Burning Law Of Solid Propellant Grains

In rockets and missiles, solid rocket motor is widely used as a power equipment. The analysis and optimize to the structure of solid rocket engine and the research on the laws of the solid propellant combustion reduction can improve the efficiency of rocket engine. The hit probability of rockets and missiles were increased. The warheads control was increase, the power of missile was improved.In this paper, the strength analysis and optimization design to missile engine of combustion chamber shell of threaded connection and thermal stress analysis to nozzle of composite structure were based on the finite element method and experiment method. In order to deduce the formulas that is the buring area of grain reduction by the analytic method. By studying the combustion rule of grain, the selection criteria of star-shaped grain, wheel-shaped grain, sleeve-shaped grain and short tubular grain were gained.Firstly, the missile engine structural strength of missile engine of threaded connection was analyzed, the thread joint contact was defined, the combustion chamber shell wall thickness was optimized design by goal-driven optimization method. The results show that the intensity of the combustion chamber shells with threaded connection can work reliably, and the maximum stress point is in the smaller transition arc of the front case. After the water pressure test and the motor test, the structure of the shell is complete, which prove that the structure strength meets the requirements. The total mass can be reduced by 4.5%.Secondly, the temperature distribution of combustion flow field of nozzle of composite structure was analyzed, temperature distribution of combustion flow field of the nozzle will be loaded into the nozzle inside the type face, the temperature distribution in the nozzle was got, heat stress of nozzle was solved by the heat – structure coupling. The results show that temperature of nozzle shell was lower than that of ablation resistant layer, temperature of parts without insulation is higher than that of adding thermal insulation parts. The contact temperature gradient in the different material is the largest. Maximum thermal stress points of nozzle of composite structure was contact of the ablation resistant layer and shell. Temperature distribution of finite element analysis were similar to surface of the nozzle ablation after hot commissioning. Nozzle of composite structure was full after hot commissioning.Thirdly, the study on regressive burning of star-shaped grain, wheel-shaped grain, sleeve-shaped grain and short tubular grain. Results show that the regressive buring of star-shaped grain and wheel-shaped grain are bigger, and the adjustable range of the degression buring is big. Regressive buring of sleeve-shaped grain and short tubular grain are smaller. When the degressive nature is small, the short tubular grain is selected preferentially.When the star angle of the star-shaped grain and the wheel arm of the wheel-shaped grain have the same number, further more, they have the same regressive burning, the filling factor and web thickness of star-shaped grain will be bigger than wheel-shaped grain. When degressive nature is big, star-shaped grain is selected preferentially.