背压脉动引起的超声速进气道流固耦合振动分析

Fluid-Structure Vibration Analysis of an Supersonic Intake

关键词:  冲压发动机  进气道  压力脉动  流固耦合振动  阻尼

Key words:  Ramjet engine  Intake  Pressure fluctuation  Fluid-structure vibration  Damping

摘要:

冲压发动机燃烧室压力脉动对进气道形成背压脉动，影响了进气道内流动的稳定性。采用数值仿真方法，研究了背压脉动作用下超声速进气道内非定常流动与局部弹性壁板的流固耦合振动问题，分析了壁板阻尼对进气道流固耦合振动问题的影响。结果表明，弹性壁板振动形成了“动态空腔”效应，大幅降低了激波串振荡幅值，增加了非定常流动稳定性。其中，无阻尼弹性壁板模型的激波串振荡幅值下降为刚性壁板模型结果的45.6%。通过增加壁板阻尼的方式，能够增强壁板振动的“动态空腔”效应。当刚度比例阻尼系数为10-4时，激波串振荡幅值降为刚性壁板模型结果的43.7%。

Abstract:

Pressure fluctuation in ramjet combustor produces back pressure oscillation on the aero intake，which affects flow stability in the intake. Fluid-structure vibration between unsteady flow in a supersonic intake and local flexible wall was simulated under back pressure oscillation，and the effects of flexible wall damping on fluid structure vibration were analyzed. It is shown that “dynamic cavity” effect is formed by flexible wall vibration，which limits the shock train oscillation amplitude and stabilizes unsteady flow in the intake. Oscillation amplitude of shock train in a flexible wall model without damping is limited to 45.6% of that in rigid wall model result. “Dynamic cavity” effect can be amplified through adding flexible wall damping. With a stiffness proportional damping coefficient of 10-4，shock train oscillation amplitude is reduced to 43.7% of that in rigid wall model result.