固体火箭发动机燃烧室轴向平均流速对声模态影响研究

The Study of Axial Mean Flow Velocity of Solid Rocket Motor Combustion Chamber on Acoustic Mode

固体火箭发动机不稳定燃烧与发动机燃烧室声模态特性密切相关,降低燃烧室声模态频率与涡脱落频率之间的涡声耦合程度可以大大降低固体火箭发动机不稳定燃烧发生的概率。然而,目前关于发动机燃烧室声模态特性研究主要基于燃烧室内燃气介质静止状态,而没有考虑固体火箭发动机实际工作中燃气介质的流动特性。本文以大长径比固体火箭发动机不稳定燃烧现象为背景,通过理论推导与数值计算相结合的方法研究轴向平均流速对燃烧室模态频率的影响机理。研究结果表明,平均流速的存在不仅产生附加刚度项,而且产生系统附加阻尼项,从而改变了燃烧室声模态特性。

The unstable combustion of solid rocket motor is closely related to the acoustic modal characteristics of the combustion chamber,reducing the coupling between the combustion chamber and the vortex shedding frequency can greatly reduce the occurrence of unstable combustion.However,the present research are mainly based on the static state of the medium in the combustion chamber,the mean flow characteristic of the gas medium in the combustion chamber are not considered.This paper is based on the unstable combustion of solid rocket motor with large aspect ratio,through theoretical derivation and numerical simulation to research the mechanism and characteristics of axial mean flow velocity on chamber frequency.The results show that the existence of mean flow not only changes the stiffness characteristics of the combustion chamber,moreover,a damping term proportional to the mean flow velocity is also generated,thereby the acoustic modal characteristics of the combustion chamber is changed.