Research On The Dynamic Characteristics Of The High-pressure Gas Circuit And Key Components Of A Propulsion System

As an important part of ensuring the aircraft normal operation,the high-pressure gas circuit of the propulsion system mainly provides stable pressure and flow for downstream circuits and components.The performance of the high-pressure gas circuit directly affects the quality of space missions.In order to improve the performance of the high-pressure gas circuit of the propulsion system,this dissertation focuses on studying the high-pressure gas circuit and components of a certain aerospace propulsion system.Based on the methods of power bond graph,numerical simulation,experimental verification and response surface analysis,relevant researches on the operating characteristics of the high-pressure gas circuit and key components are carried out.The main research contents are as follows :The composition and principle of the high-pressure gas circuit of the propulsion system were explained.The power rheological model of the air vessel,the dual-stage gas pressure reducing regulator,and the direct-acting gas pressure safety valve were established based on the bond graph method.Combining the continuity and energy equation of the fluid,the working process of the dual-stage gas pressure reducing regulator and the direct-acting pneumatic safety valve were mathematically analyzed.The mathematical model of the high-pressure gas circuit and key components of the propulsion system dynamic characteristics were established.Based on the theory of finite element analysis(FEA),computational fluid dynamics(CFD),and fluid structure interaction(FSI),the working conditions of the internal flow field of the dual-stage gas pressure reducing regulator during the working process was studied and the influence of the regulator's internal flow field change on the structure was analyzed.Aiming at the characteristics of large deformation and high sensitivity of the regulator's feedback diaphragm,the mechanical characteristics of the feedback diaphragm under different structures and materials were studied.The mechanical characteristics of the seal ring of the direct-acting pneumatic safety valve were analyzed based on the FEA theory.And the influence of the structure,shape and pre-compression on the seal deformation and maximum contact stress of the seal ring were studied.The flow field characteristics of the direct-acting pneumatic safety valve were studied based on the FSI theory.The distribution of the pressure field and velocity field inside the safety valve were obtained,and the coupling behavior of the flow field characteristics to the structure of the safety valve were analyzed.Using the power rheological model and mathematical model of key components of the high-pressure gas circuit to establish the AMESim simulation model of the high-pressure gas circuit and verify the simulation model based on the experimental data;Considering the consistency of simulation and experimental results,AMESim simulation is used to study the influence of design parameters on the primary and secondary structures of the two-stage gas pressure reducer and the dynamic characteristics of the direct-acting pneumatic safety valve.Based on the statistical results of AMESim simulation results,the response surface analysis method(RSM)is used for regression analysis to obtain the regression equations of the design parameters affecting the output characteristics of the I-stage and II-stage structure of the dual-stage gas pressure reducing regulator,and identify the significance of the design parameters and the interaction effects.Using NSGA-II algorithm,the regression equations were optimized with multiple objectives,and obtained the optimal design parameters of the I-stage and II-stage structure of the dual-stage gas pressure reducing regulator.The results obtained in this dissertation can provide research ideas and technical means for improving the performance of the high-pressure gas circuit of the propulsion system,and also provide a certain reference for the design and optimization of the dual-stage gas pressure reducing regulator and the direct-acting pneumatic safety valve.There are 119 pictures,38 tables and 123 references in this dissertation.