头部空腔对固体火箭发动机压强振荡抑制作用的数值研究

为了揭示头部空腔对固体火箭发动机压强振荡的抑制原理,以VKI实验发动机为基础,使用大涡模拟方法,对障碍物旋涡脱落诱发的振荡流场开展了数值研究,获得了压强振荡的频率和幅值,并和实验数据进行了对比。通过在发动机头部加入空腔,发现压强振幅明显减弱,证实了瑞利准则用于指导头部装药抑振设计的有效性。研究结果表明,空腔体积、位置、形状对振幅的影响很大,改变装药结构本质上是质量抽取与注入之间的相互抗争过程。装药头端复杂流场对抑振基本无效,在声压波节处改变药型对抑振基本无效,在声压波腹处加入的质量通量越大,振幅增加越显著,空腔越靠近声压波腹,空腔对声能的阻尼效应越强。

Numerical analysis on effect of head cavity on resonance damping characteristics in solid rocket motors

In order to reveal the effect of head-end cavity on resonance damping characteristics in solid rocket motors,large-eddy simulations were carried out to study the oscillation flowfield induced by obstacle vortex shedding on the foundation of VKI experimental motor.Pressure oscillation frequencies and amplitudes were obtained,and compared with the experimental data.It is investigated that oscillation amplitudes reduce remarkably after adding a cavity at the head-end.It is proved that Rayleigh criterion is effective for design of resonance damping.The results indicate that cavity volume,location and configuration have great effect on the oscillation amplitude.The substance of altering grain configuration is a comprehensive process of adding and extracting mass.The damping effect is not caused by the complicated flowfield at the head-end.Also,it is neglected if altering grain configuration at the pressure node.It is concluded that large mass flux added at pressure antinode could result in significant amplitude;meanwhile,the damping effect of cavity is stronger if the cavity is nearer to pressure antinode.