补燃循环发动机强迫起动过程

以补燃循环液氧煤油发动机系统为研究对象,对其强迫起动特性进行了研究.建立了描述补燃循环发动机瞬变过程的数学模型,提出了求解推进剂供应管路瞬变流控制方程的Chebyshev伪谱方法.采用新的面向对象仿真语言Modelica,建立了可扩展的发动机仿真模型库,在MWorks平台上,利用模型库搭建了补燃循环液氧煤油发动机仿真模型.对发动机强迫起动过程进行了仿真计算,计算结果与试车数据基本相符,其中稳态相对误差小于4%,动态相对误差小于10%,初步验证了模型的正确性.进一步分析了火药起动器工作时间、阀门打开时序等因素对发动机起动过程的影响.结果表明,为保证该发动机可靠起动,发生器点火应在氧化剂头腔充填完成后,火药起动器工作时间应持续到发生器点火. 

Forced start-up procedure of a staged combustion cycle engine

Using the advanced staged combustion cycle LOX (liquid oxygen)/kerosene engine as an example, the engine start-up characteristics were investigated. The mathematical model of transient process of the engine was developed based on modular modeling means. The nonlinear hyperbolic partial differential equations governing the unsteady flow of propellant pipelines were solved by the Chebyshev pseudo-spectral method. Furthermore, an extensible simulation library for liquid propellant rocket engines has been elaborated by using the new object-oriented simulation language-Modelica. Simultaneously, by using the simulation library, a staged combustion cycle LOX/kerosene engine model is built on the platform MWorks and forced start-up characteristics of the engine calculated. Results from the numerical simulation agree well with the ground-test data, the relative errors of steady-state are less than 4%, and the dynamic simulation errors are less than 10%, which indicates that the model can accurately predict the transient behavior of the engine. Some rules relating to start-up were simulated. The results demonstrate that solid propellant starter working should be lasted up to the gas generator ignition, and gas generator head should be filled with liquid oxygen when gas generator igniting.