基于燃气射流冷凝的氧路系统频率特性研究

Study on frequency characteristics of oxygen feed system based on gas jet and condensation

基于热力学不平衡两流体六方程模型模拟了液氧煤油补燃循环发动机燃气射流在氧路系统泵间管路液氧流体中的冷凝过程,获得了燃气射流冷凝特征参数沿管路流向的分布规律。根据Rayleigh-Plesset方程和燃气射流特性建立了泵间管路燃气冷凝过程的传递函数模型,并与氧路管路、泵等组件模型联立求解,分析了发动机氧路系统频率特性。研究了在不同氧路入口压力和液氧温度边界条件下,泵间管路燃气射流冷凝过程对氧路系统频率特性的影响,仿真结果表明高入口压力和过冷液氧改变了射流气体的惯性和柔度,使得氧路系统特征频率增大。不同边界条件下发动机热试车结果表明,提高氧路入口压力或降低液氧温度使得氧路系统频率从8.3Hz提高至11Hz,与数值仿真结果一致,验证了泵间管燃气射流冷凝过程是影响氧路系统频率特性的重要环节。

Based on the one-dimensional thermodynamic disequilibrium two-fluid six-equation model,the condensation of gas jet is simulated.The simulation happens in the pipeline between pumps of the liquid oxygen/kerosene staged combustion cycle rocket engine system,obtaining the characteristic parameters along pipeline flow direction.Firstly,based on Rayleigh-Plesset equation and the characteristics of gas jet and condensation distribution,a transfer function model is established.The condensation model with liquid oxygen pipeline,pump,and other component models are solved simultaneously,and the frequency characteristics of oxygen pipeline system of the engine are analyzed.Secondly,the influence of gas jet and condensation process on the frequency characteristics of the oxygen feed system at different inlet pressure levels and liquid oxygen temperature boundary conditions are studied.The simulation results show that the high inlet pressure and subcooling liquid oxygen changes the inertia and flexibility of jet bubble,and increases the characteristic frequency of the oxygen feed system.The engine firing test results under different boundary conditions show that increasing the oxygen feed system inlet pressure or decreasing the liquid oxygen temperature increases the frequency of oxygen feed system from 8.3Hz to 11Hz.The result is consistent with the numerical simulation results,verifying that gas jet and condensation of pump pipeline is an important process affecting the frequency characteristics of the oxygen feed system.