固体火箭发动机喷管扩张段壳体结构优化设计

Optimal design on solid rocket motor nozzle divergent cone

针对某型号发动机喷管扩张段壳体结构,建立了高精度三维扩张段热结构FEM模型,计算了喷管工作时扩张段壳体结构在承受高温、高压以及作动器外载的联合作用下,结构的应变及位移分布规律,并与全尺寸发动机喷管热联试的试验结果作对比。结果表明:热结构仿真计算与试验结果吻合较好,其中关键承载部位应变最大误差小于15%,验证了热结构仿真模型准确性及精度,可以用于工程上扩张段壳体热结构强度校核。在此基础上,以环/母向筋条数量为设计变量,采用First-order优化方法对喷管扩张段壳体结构进行减重优化设计,在满足强度和刚度要求的前提下实现了目标结构约30.8%的有效减重。以上计算结果对于固体火箭发动机喷管扩张段壳体结构设计优化,准确预估结构安全裕度有着一定的参考价值。

The high-precision 3D thermal-structure simulation model of a SRM (Solid Rocket Motor) nozzle divergent cone was developed by using FEM (finite element method) method.The strain and displacement distribution of the exit structure under the complex condition of high temperature, high pressure and the actuator loading together were calculated and compared with the full scale nozzle ground firing test results.It indicates that the simulation results are in good agreement with the test results.It verifies the accuracy and validity of 3D simulation model efficiently.The maximum strain error of key bearing part of the exit structure is less than 15%.It can be used as the strength verification model of exit cone in engineering application.Baesd on this, the First-order optimization method was adopted to lighten the weight of the structure with numbers of ribs in hoop/axial direction as variable parameters.It was indicated by application that under the premise of satisfying the strength and stiffness, the exit cone after optimization achieved the designing target of 30.8% weight reduction.The conclusions above in this paper can provide some important guidance for nozzle exit structure design and safety tolerance prediction of solid rocket engines.