液体火箭发动机离心泵受过载变化的影响研究

Research on the Influence of Overload Change on Centrifugal Pump of Liquid Rocket Engine

运载火箭在飞行过程中存在较大的过载变化,液体火箭发动机离心泵入口压力也会相应变化。为分析清此情况下离心泵瞬态气蚀流场特性与稳态气蚀流场特性的区别,从气蚀模型的角度出发,采用了一种基于Rayleigh–Plesset气蚀模型的仿真方法。通过对Rayleigh–Plesset方程进行数值求解,理论上分析了离心泵非稳态流场与稳态流场气蚀特性的区别,之后对离心泵诱导轮建立了三维模型,分别应用基于Rayleigh–Plesset气蚀模型的非稳态仿真方法与稳态仿真方法,求解了不同入口压力下的瞬态流场与稳态流场离心泵诱导轮内气相体积分数的数值。仿真结果表明,同一入口压力下瞬态流场的气相体积要低于稳态流场,稳态流场的气蚀程度要重于瞬态流场;且气相体积分数的差值随着入口压力变化率的增大而加大,二者气蚀程度的区别也随之变大。

There is a large overload changes during the flight process of rocket,leading to the consequent change in the inlet pressure of liquid rocket engine centrifugal pump.In order to analyze and understand the difference between the characteristics of transient cavitation flow field and the characteristics of steady cavitation flow field of centrifugal pump,a simulation method based on Rayleigh -Plesset cavitation model was adopted.Based on the numeri-cal calculation of Rayleigh-Plesset "equation,the cavitation characteristic difference between unsteacly-state flow and steady-state flow was analyzed theoretically.Then,a 3D model of inducer was established.Based on Rayleigh-Plesset cavitation model,both the steady-state simulation method and unsteady-state simulation method were used to calculate the volume fraction of the gas phase fraction of inducer flow field under different inlet pressure.The results indicate that the gas phase fraction of the unsteady-state flow field is lower than that of the steady-state flow field at the same inlet pressure,so is the cavitation degree of the unsteady-state flow field.And this difference increases when the changing rate of inlet pressure is increasing.