迎风面肋板对方柱流场和气动力的影响研究

LES study of windward-face-mounted ribs’effects on flow fields and aerodynamic forces on a square cylinder

研究表明外伸肋板能显著减小高层建筑的风荷载,但此类附属构造的流场机理尚未澄清,因此,该文章采用大涡模拟方法研究了均匀来流作用下迎风面竖向肋板对方柱周围流场和气动力的影响,分析了不同模型的流场结构、风压分布和气动力,阐明了竖向肋板的流场机理。研究发现,外伸竖板使模型前角区域产生局部旋涡,该旋涡明显影响了来流的流动分离和剪切层特征。肋板的外伸长度d显著影响模型周围的流场结构、涡脱频率和风压分布。模型周围流场的变化导致平均阻力C_(d)和脉动升力C′_(l)明显减小。肋板位置参数b和d存在最佳组合,使模型上的气动力最小,当d/D=0.12和b/D=0.10时,模型的C_(d)和C′_(l)相比参考方柱减小了50%和86%。

Previous studies have demonstrated that facade ribs could significantly reduce the wind load of high-rise buildings.However,the flow filed modification mechanism of these facade appurtenances has not been clarified.In the study,large eddy simulations were carried out to investigate the impact of windward-face-mounted vertical ribs on the flow field and aerodynamic forces on a square cylinder under smooth inflow.The flow structure,wind pressure distribution and aerodynamic forces of different models were analyzed to elaborate theflow field mechanism of the vertical ribs.It is found that local recirculation is introduced in the front corner region owing to the presence of ribs,which obviously influences the flow separation and the behavior of shear layer.The rib depth d significantly affects the flow structure,vortex-shedding frequency and wind pressure distribution.The changes in the flow field result in remarkable mitigation of the mean drag C_(d) and fluctuating lift C′_(l).There is an optimal combination value of rib position parameters b and extension depth d,the aerodynamic forces are the smallest in these cases.The maximum reduction ratios of C_(d) and C′_(l) reach 50%and 86%respectively,when d/D=0.12 and b/D=0.10.