液体火箭Pogo振动蓄压器非线性仿真研究

本文针对液体火箭推进系统中的Pogo振动现象提出了一种非线性的仿真方法。传统的线性管路模型可以用来进行Pogo振动的稳定性分析;但直接用于振动过程的仿真时,却与实际发生的振动现象差别较大。这些稳定性分析方法中,蓄压器元件采用的是在工作状态附近线性化的模型,而本文从蓄压器中工作气体状态方程出发,建立蓄压器的非线性模型,并对管路和箭体结构耦合系统的状态方程进行了时域仿真。仿真结果表明非线性模型不仅可以反映出系统每个时刻的稳定性,而且可以再现Pogo振动失稳时发散和收敛的过程,特别是失稳时蓄压器处压力脉动变化的非对称特点。这些都非常符合Pogo振动的观察结果。

A nonlinear model on the simulation of pogo vibrations in liquid rockets

A nonlinear model is studied in this paper on the simulation of Pogo vibrations in liquid rockets. The original linear model can be used to analyze the stability of Pogo vibration, but the results of linear model simulation are not so satisfied. From the physical analysis of the working material, a new model of a most important element in the liquid propellant system - the Accumulator is derived. This model can be simplified and applied in the simulation of Pogo vibration, whose results can be compared with those of the linear model. It can be shown that the results of nonlinear model can not only give the precise stability analysis of each time in the vibration but also the pictures of the process are much more close to the real processes, especially it can show the un-symmetry phenomenon in the pressure, which is observed in the experiments.