液体火箭发动机热力组件动力学模型

Dynamics Models for the Combustor Component in Liquid Rocket Engine

为了评判不同假设条件下得出的几种热力组件动力学模型的特点和适用范围,对其频率特性进行分析,并探讨了主要参数的影响规律。对于双组元非等温燃气流,在低频范围内采用考虑熵波效应的绝热流动模型更加精确。燃烧温度与混合比关系的无量纲斜率值越大,推进剂流量波动产生的熵波影响越明显。通过在分布参数流动模型中添加指数衰减率来表示熵波随频率的增大而耗散。改进的声学模型形式简单,既能在低频范围内描述熵波,又能在高频范围表征熵波的耗散,可以在很宽的频率范围内合理地描述燃气流动的动态特性。

The frequency characteristics of several dynamics models for combustor component under different assumptions are analyzed respectively in order to discuss the property and applicable range of each model. For bipropellant and non isothermal gas flow, it is confirmed that the adiabatic flow model including entropy wave effect is more accurate in low frequency range. Larger slope value of the relation of combustion temperature versus mixture ratio causes more obvious effect of entropy wave under the condition of propellant flow rate fluctuation. The dissipation of entropy wave with the increase of disturbance frequency is describing by adding an index decrement in the distributed parameter flow model. The modified acoustics model proposed in this paper has a simple formulation. It not only has a good description of entropy wave in the low frequency range, but also reasonably illustrates the dissipation of the entropy wave under high fluctuant frequency. Thus the modified model can be used in wide frequency range to study the dynamics characteristics of the gas flow.