弹性支撑圆柱绕流稳定性分析  

STABILITY ANALYSIS OF FLOW PAST AN ELASTICALLY-SUSPENDED CIRCULAR CYLINDER

作　　者：李新涛[1] 张伟伟[1] 蒋跃文[1] 叶正寅[1] 

机构地区：[1]西北工业大学翼型叶栅空气动力学国家级重点实验室,西安710072

出　　处：《力学学报》2015年第5期874-880,共7页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金(11072199;11172237);教育部"新世纪优秀人才支持计划"(NCET-13-0478);陕西省"青年科技新星"计划等资助项目~~

摘　　要：基于CFD技术,采用系统辨识方法,建立了亚临界雷诺数(Re<47)下绕圆柱流动的非定常气动力模型(reduced order model,ROM).耦合结构运动方程和降阶气动力模型,建立了弹性支撑圆柱绕流的稳定性分析模型.算例分析了亚临界雷诺数下,结构固有频率、质量比等参数以及支撑方式对弹性系统稳定性的影响.对于单自由度横向支撑圆柱,当结构固有频率趋近流动最不稳定模态频率时,弹性系统会在一定频率范围内失稳,这种现象最低可在Re～20时出现.旋转自由度的释放能够进一步降低系统的稳定性,可将临界雷诺数进一步降低至18左右.ROM方法不仅具有很高的效率,而且清晰地指出了弹性系统失稳的根本原因:流动模态和结构模态耦合作用导致结构模态失稳所致.因此,失稳状态下系统振荡频率锁定于结构固有频率.基于ROM技术预测的失稳边界与直接CFD/CSD仿真结果吻合,证明了该方法的正确性和精度.An identification technique is used to construct reduced order models （ROMs） for the cylinder wake flow at subcritical Reynolds numbers （Re 〈 47） using CFD simulation data. ROM-based aeroelastic models are then found by coupling the structural motion equations and ROMs. The impacts of structural frequency, mass ratio and mount style on the instability boundaries are investigated. It is found that self-excited oscillations, accompanied by vortex shedding are possible at Re as low as 20 for one freedom transversely suspended cylinder, as the structural frequency gets close to that of the most unstable mode of flow. The release of rotational freedom could further increase the instability of the coupled system and the critical Re can be reduced to 18. ROM-based method not only has high efficiency but also profoundly shows that the inherent instability of the coupled system is induced by the unstable of the structure mode. Therefore, in the unstable region, the vibration frequency of the coupled system is synchronized with the natural frequency of the cylinder.

关 键 词：圆柱绕流 系统辨识 降阶模型 涡致振动 稳定性分析 

分 类 号：V211-3[航空宇航科学与技术—航空宇航推进理论与工程]