均匀流中箱梁非定常风压的频域特征和空间相关性  

Frequency-domain Characteristics and Spatial Coherence of Unsteady Wind Pressure on Box Girder Surface in Smooth Flow

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：《中国公路学报》2014年第6期68-76,共9页China Journal of Highway and Transport

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

摘　　要：为研究箱梁脉动风压的频域特征和空间相关性,采用大涡方法模拟了箱梁在0°风攻角和雷诺数为1.27×105下的绕流场,获得了主梁表面脉动压力分布和统计特征,开展了脉动压力时程的频域和空间相干性分析,解释了脉动压力的流动机理。研究结果表明:主梁尾迹的主脱落漩涡主导了主梁表面脉动压力,且涡脱存在频率带宽分布和展向不同步特征;主梁下表面脉动压力同相相关,但顶板脉动压力受分离再附流的干扰,上游风嘴及附近的脉动压力漂移了180°相位,导致上表面前、后风嘴上的脉动压力反相,且流动平均再附点后较大区域,脉动压力相干性小且相位杂乱。In order to investigate the frequency-domain characteristics and spatial coherence of fluctuating pressure on box girder surface, large eddy simulation （LES） was employed to simulate the flow field at zero angle of attack with Re of 1.27×10^5. The fluctuating pressure distribution and their statistical characteristics were obtained. Spatial coherence analysis and frequency-domain analysis of fluctuating pressure time history were carried out to investigate the flow mechanism. The results show that the primary shedding vortex in the wake dominates the fluctuating pressure field, and vortex shedding indicates a band width distribution in frequencydomain due to not simultaneous shedding in span-wise direction. The pressure records on girder lower surface are highly correlated in-phase, while the pressures on upper surface is significantly interfered by the reattachment flow, resulting in a 180 degree phase shift between pressures on the leading and trailing air fairing. Consequently, the fluctuating pressure on the upper surface of the leading air fairing is completely in antiphase with that of the trailing air fairing, and the correlation of fluctuating pressure at large area behind the average flow reattachment zone is significantly decreased with random phase.

关 键 词：桥梁工程 箱梁 大涡模拟 漩涡脱落 脉动压力 相干分析 

分 类 号：U448.213[建筑科学—桥梁与隧道工程]