喷管温度与应力场的数值研究

为了使喷管能安全可靠的工作,在喷管设计中必须考虑热防护问题从而避免喷管内部的严重烧蚀.文中考虑了喷管的几何特性和热分析过程中的主要因素,建立起轴对称的有限元计算模型,在给定的热边界条件下计算了喉衬组件与扩张段结构的瞬态温度场.在喷管轴对称模型瞬态热分析的基础上研究了轴对称载荷下热-结构耦合场的应力分析.应力场的计算采用以位移为未知变量的有限元法,并考虑了耐烧蚀层材料的物性参数随温度的变化.计算结果与分析表明在材料的交接面处应力较大,喷管各层材料间的膨胀系数差异对应力的影响较大.该研究结果可供火箭发动机喷管设计参考.

Numerical study of temperature and stress fields of nozzles

For safe and reliable operation of nozzles, it is necessary to know how to design them to avoid heat ablation. In this paper, effects of the geometry of nozzles and the major factors involved in heat analysis were considered. An axis-symmetrical finite element model was established. The transient temperature fields of throat modules and expansion zones were computed under given heat boundary conditions. Then stress analysis was made for the heat-structure-coupled fields of nozzles with axis-symmetrical loading. Using the FEM method, displacement was treated as an unknown variable, and changes in physical parameters of an anti-ablation layer were taken into account. From observed results, we find that the highest stresses occur at interfaces between different materials. Disparities in thermal expansion coefficients of materials have a great influence on stress distributions in nozzles. The results and the method presented in this paper can be a reference to the design of nozzles in rocket motors.