某发动机整机模态分析

Modal analysis of a rocket engine

为了获得某型号发动机的动态特性,采用有限元方法进行了发动机整机的模态分析。按照由组件到整机的思想,分别建立了各个组件的有限元模型。重点对推力室和喷管的建模方法进行了分析。将推力室按等效刚度法等效为单层壳,喷管按结构特性等效为正交各向异性壳,并将喷管计算结果同模态试验结果进行对比,验证了喷管建模方法的准确性。各组件模型组装为整机有限元模型,计算得到了整机的模态分布。数值计算结果同模态试验结果吻合较好。

To obtain the dynamic characteristics of a certain rocket engine, a modal analysis for the engine is conducted with finite element method （FEM）. According to the idea from components to integrate, the finite element model for each component is established. In addition, the modeling methods for nozzle and thrust chamber are analyzed emphatically. The thrust chamber is simplified to single-layer shell by stiffness equivalent, while the nozzle is simplified to orthotropic shell in accordance with its structural properities. The calculated result of nozzle is compared with that of modal experi- ment to verify the precison of the modeling method for nozzle presented in this paper. The finite element model of whole engine is assemblied by all the component models, and then its modal distribution is calculated. The result of numerical calculation agrees well with that of modal test.