推力室冷却通道结构可靠性仿真及参数敏感性分析

为了准确高效评估液体火箭发动机推力室身部再生冷却通道的结构可靠性,建立了基于有限元热结构耦合计算的结构可靠性仿真流程。考虑发动机干扰因素、身部结构尺寸及内外壁材料性能的随机性,利用Monte Carlo(MC)仿真和Epps-Pulley(EP)检验确定危险点的等效应力分布,根据基于参数估计区间的应力-强度干涉模型及点估计下限和Lindstrom-Maddens(L-M)法,确定冷却通道结构可靠度置信下限,并进行参数敏感性分析。结果表明:该结构可靠性仿真能够确定内壁失效的危险点,得到工程上更具实用价值的可靠度置信下限；外壁的强度裕度远大于内壁,冷却通道的结构可靠性取决于内壁；提高推力室燃烧效率或选用导热率稍低,而强度更高的内壁材料,是提高冷却通道结构可靠性的有效途径。 

Structural reliability simulation and parameter sensitivityanalysis of cooling channel for thrust chamber

In order to evaluate the structural reliability of regenerative cooling channel in thrust chamber body for liquid rocket engine, a structural reliability simulation procedure was established based on finite element thermal-structure coupling calculation. Considering the stochastic influence of engine systems interfering factors, the chambers machining dimension and material performance of the chamber wall, the distribution type of equivalent stress in dangerous points was determined by means of Monte Carlo(MC) simulation and Epps-Pulley(EP) test method. Lower confidence limit of reliability for cooling channel was determined by use of a stress-strength interference model based on the parameter estimation interval, point-low confidence limit method and Lindstrom-Maddens(L-M) method. Then parameter sensitivity was analyzed. Results indicated that dangerous points of inner wall were determined according to the structure reliability simulation, and lower confidence limit of reliability was obtained, making it more practical in engineering. The strength margin of outer wall was much greater than that of inner wall and the structural reliability of cooling channel depended on inner wall. It was an efficient approach to improve structural reliability by enhancing combustion efficiency or selecting inner materials with slightly lower thermal conductivity and higher strength.