固定直圆柱随机脉动升力特性的数值模拟  

Numerical Simulation of Stochastic Characteristics of Fluctuating Lift on a Fixed Circular Cylinder

作　　者：祝志文[1] 

机构地区：[1]湖南大学土木工程学院,湖南长沙410082

出　　处：《西南交通大学学报》2013年第6期975-982,共8页Journal of Southwest Jiaotong University

基　　金：国家自然科学基金资助项目(50978095;51278191);教育部长江学者和创新团队发展计划资助项目(IRT0917)

摘　　要：为验证大涡模拟在风工程研究上的适用性,数值模拟了固定三维直圆柱在雷诺数(Re数)为4.11×104下的绕流场,获得了圆柱非定常气动力,得到了与文献结果接近的升力脉动RMS值和漩涡脱落斯特劳哈尔数(Sr数);提出了基于90°和270°点脉动压力时程的互相关系数和RMS值,估算圆柱截面脉动升力RMS值的经验公式;开展了圆柱表面脉动压力时程的相干性分析和气动力产生的流动机理研究.研究揭示了圆柱涡脱的空间不同步和频率随时间的变化特征,以及涡脱能量的有限频率带宽分布;表明圆柱表面的脉动压力能量均集中在漩涡脱落频率上,且圆柱表面90°和270°点脉动压力时程具有完全相同的统计特性.In order to investigate the applicability of large eddy simulation（ LES） in wind engineering research,numerical simulation was carried out for flow field around a circular cylinder at Re = 4. 11 × 104. The obtained mean and root mean square（ RMS） component of fluctuating pressure and the vortex shedding Strouhal number are in good agreement with the results from available reports. An equation,based on the correlation coefficients between 90° and 270° position and RMS of the fluctuating pressure at those two points,was presented to estimate the sectional fluctuating lift on the cylinder. Coherent analysis was carried out between fluctuating pressures on circular surface,and the flow mechanism of aerodynamic forces was discussed in view of the coherence function of the fluctuating pressures on cylinder surface. It is found that the vortex shedding is not in-phases along the span-wise direction,and the vortex shedding frequency varies with the flow time. In particular,the vortex shedding energy is concentrated on a narrow band of frequency,while the pressure fluctuating energy is concentrated on the vortex shedding frequency; the fluctuating pressure time series at 90° and 270° on the opposite shoulder of the circular share the same statistical features.

关 键 词：涡脱 固定圆柱 大涡模拟 气动力 Sr数 

分 类 号：U442[建筑科学—桥梁与隧道工程]