The Study Of The Stability Analysis Technique Based Nonlinear Theory For Liquid-Propellant Rocket Engine

This emphasis of the present dissertation was focused on methodology study.The nonlinear dynamics method based on time series analysis was introduced in the stability analysis of liquid-propellant rocket engine(LRE) for the first time.Firstly,the dynamic model of liquid-propellant rocket has been established,then the time series of combustion chamber pressur-e which can reflect the dyamic characters of liquid-propellant rocket engine system was calculat-ed by numerical algorithm.After that the phase space was reconstructed to observe the structure of attractor of phase space,which can be used for qualitative anaysis.Finally,the maximum Lyapunov exponent and correlation dimension of engine system was calculated for quantitative determination.The stability of a pump-fed liquid-propellant rocket engine and the start process of a space liquid-propellant rocket engine were analyzed by the developed method.The results were draw to a conclusion that the pump-fed liquid-propellant rocket engine which seems to be stable,but has potential instability in fact.The time sequence of the start process of the space liquid-propellant rocket engine was designed optimally based on the stability analysis,and an optimal time-delay value of the fuel value was obtained.The start process of a dynamic system of a space liquid-propellant rocket engine has been reconstructed with a nonlinear predictive theory of time series,which employed a fitting function of polynomial to express dynamic performance of the system.Then the spectrum of Lyapunov exponent has been calculated with reconstructed dynamic system.It is not only a theoretical innovation of system analysis of LRE,but also an innovation of algorithm for computing the Lyapunov exponent.A new thought and a new way of the LRE stability analysis method has been presented in this dissertation,which also will expand the study field of system analysis of liquid-propellant rocket engine.