涡脱位置及温度对涡声效应压力振荡影响

Effects of Vortex Shedding Position and Temperature on Vortex-Acoustic Pressure Oscillation Characteristics

关键词:  固体火箭发动机  涡-声效应  旋涡脱落  压力振荡  耦合及解耦分析

Key words:  Solid rocket motor  Vortex-acoustic effect  Vortex shedding  Pressure oscillation  Coupling and decoupling analysis

摘要:

为探索涡-声效应对固体火箭发动机中压力振荡特性的影响,基于VKI (Von Karman Institute for Fluid Dynamics)发动机,通过改变挡板位置与燃气温度,对旋涡脱落引起的压力振荡进行了大涡模拟数值研究。耦合分析表明:挡板位于速度波腹附近,压力振荡最为严重；旋涡能量在输运过程中易于被湍流耗散,靠近喷管的二阶速度波腹处旋涡脱落压力振幅明显高于其它位置。解耦分析表明:温度对旋涡脱落频率影响不大,当旋涡脱落频率与声振频率分离后,压力振幅显著下降。 

Abstract:

To explore the vortex-acoustic effect on pressure oscillation characteristics in solid rocket motors, different cases with variation of inhibitor position and gas temperature were numerically studied via the Large Eddy Simulation (LES) method based on the VKI motor. The aim of this work is to study the mechanism of pressure oscillations induced by vortex shedding. The coupling analysis indicates that pressure amplitude reaches to a high level when the inhibitor is located at the acoustic velocity antinodes. Vortex energy can be easily dissipated by turbulence during the transport process. The vortex shedding pressure amplitude at the second acoustic velocity close to nozzle head is larger than that of others. The decoupling analysis shows that temperature has little effect on vortex shedding frequency. Pressure amplitude rapidly decreases when the vortex shedding frequency departs from natural acoustic frequency.