液体火箭发动机喷管简化建模及模型修正

Simplified Modeling and Model Correction of a Liquid Rocket Engine Nozzle

关键词:  液体火箭发动机  喷管  简化建模  模态计算  模型修正

摘要:

为了准确掌握喷管的动力学特性，提出了一种等效简化建模结合试验数据的模型修正方法。首先，将喷管的原始几何模型经过几何处理成简化模型，建立了喷管的有限元模型，对有限元模型在自由条件下进行模态计算，将得到的计算数据与测试数据对比分析，再利用测试数据对有限元模型的弹性模量参数进行修正，修正后的喷管有限元模型前9阶模态计算结果与测试结果频差在5%以内，MAC值（模态置信准则）在0.8以上。表明此方法是一种高效可行的喷管简化建模方法，既保证了精度又提高了计算效率，对其动力学特性分析、振动响应预测等方面具有重要应用价值，对于液体火箭发动机其他部件的动力学建模及分析也具有普适性。

Abstract:

Nozzle is an important component of liquid rocket engine. Its dynamic characteristics have an impact on the reliability of the whole engine in service. Accurate understanding of nozzle dynamic characteristics is of great significance for response prediction, fault diagnosis and improvement design of liquid rocket engine. An equivalent simplified modeling method that combines model correction based on experimental data is proposed. Firstly, the original geometric model of nozzle was simplified by geometric processing, and the finite element model of nozzle was established. The modal calculation of the finite element model was carried out under free condition. The calculated data were compared with the test data, and then the elastic modulus parameters of the finite element model were modified by the test data. The first nine order modal calculation results and measurement of the modified finite element model of nozzle are obtained. The frequency difference between the first nine order modal calculation results of the modified finite element model of nozzle and the measurement results are less than 5%, and the MAC (Modal Assurance Criterion) is more than 0.8. It shows that this method is a highly efficient and feasible nozzle simplified modeling method, which not only ensures the calculation accuracy but also improves the calculation efficiency. It has important application value for its dynamic characteristics analysis and vibration response prediction. It is also universal for dynamic modeling and analysis of other components of the rocket engine.