固体火箭发动机涡声耦合特性数值研究

Numerical analysis on vortex acoustic coupling characteristics in solid rocket motors

关键词:  固体火箭发动机  涡/声耦合  旋涡脱落  振荡特性

Key words:  Solid rocket motor  Vortex acoustic coupling  Vortex shedding  Oscillation characteristics

摘要:

为了揭示固体火箭发动机内涡/声耦合机理,以VKI实验发动机为基础,使用大涡模拟方法,对不同温度下障碍物旋涡脱落诱发的振荡流场开展数值研究,获得了燃烧室内速度分布以及压力振荡的频率和幅值,并和实验数据进行了对比。结果表明,旋涡脱落频率与某阶声振频率相等不是涡/声耦合的必要条件；速度幅值对旋涡脱落频率的影响是主要的；平均马赫数对旋涡脱落频率的影响不大,对压力振幅的影响显著。 

Abstract:

In order to discover the mechanism of vortex sound coupling in solid rocket motors, large-eddy simulation with wall-adapting local eddy-viscosity subgrid-scale turbulence model was carried out to study the oscillation flowfield induced by obstacle vortex shedding on the foundation of VKI experimental motor. Several cases with various inlet temperatures were presented to investigate parameters which impact the oscillation characteristics. Velocity profiles, vortex shedding frequencies, acoustic frequencies and oscillation amplitude were obtained, and then compared with the experimental data. The results indicate that it is not a necessary condition that vortex shedding frequency equals one acoustic frequency when vortex sound coupling happens. It is not the mean Mach number but velocity magnitude in the combustion chamber mainly that affects on the vortex shedding frequency. Meanwhile, the oscillation amplitude is mainly determined by the mean Mach number.