Analysis And Control Of The Structural And Damage Madel Of Thrust Chamber Inliquid Propellant Rocket Engine

Based on the damage mitigating control (DMC), this thesis focuses on the damage analysis and control of the coolant channel ligament which is treated as one of critical components for the liquid-propellant rocket engines (LRE) during a transiting operating condition.Firstly, some general methods of the DMC for LRE are clarified. The concept of the DMC is introduced. In general, to synthesize the control law of the DMC, it is necessary to combine the LRE system dynamics with the structural and damage models of critical components when the damage of the critical components is evaluated. Then, the plant lifetime is predicted. The damage mitigating and life extending controller is designed with taking the LRE performance specifications and damage rate and accumulation of critical components into account. Consequently, the optimal control input sequence is imposed on the LRE to reduce the accumulated damage of critical components so as to extend the service lifetime of the system.Secondly, the standard lumped parameter approach has been used to model the thermo-fluid dynamics of the liquid propellant rocket engine. During the process in which the combustor chamber pressure transfers from 14.48MPa to 20.68MPa, five kinds of various steady operating conditions are simulated, respectively. The performance specifications are obtained under these conditions. Subsequently, the structural and damage dynamics of the coolant channel ligament are analyzed and modeled. Damage rates and distributions of the coolant channel ligament are evaluated under the preceding five different combustor chamber pressures. The simulation results indicate that damage accumulation of the coolant channel ligament is markedly reduced, while the combustor chamber pressure slightly degrade.Finally, an intelligent damage controller based on the fuzzy-logic is studied. And it can implement to control the accumulated damage of the coolant channel ligaments of the rocket nozzle. The simulation results show that the effect of damage mitigating controller is very effective.The study results of the thesis imply that the sandwich beam structural model, the viscoplastic model and the time-dependent damage model utilized have high numericalefficiency, and can meet the requirement for the real-time ability, while the model of continuous damage rate developed is potential to on-line application. Additionally, the fuzzy damage-mitigating controller has very well damage-mitigating effect, and may be suitable for on-line applications of service lifetime prediction and damage control for the LRE.