正方形顺排排列四圆柱流致振动响应研究

摘要

Flow-induced vibrations of four square-arranged circular cylinders with a center-to-center spacing ratio of s /D =5.0 and zero attack angle were numerically investigated.The vibrations were constrained in cross-flow direction,the reduced flow-velocity was in the range of Ur =2.0 ~50.0 and Reynolds number was Re =100.Results showed that the responses of two upstream cylinders are similar to those of VIV of an isolated cylinder,the initial and lower branches are clearly observed;the upstream two cylinders reach their maximum vibration amplitude of Ymax /D =0.56 at the reduced flow-velocity Ur =4.4,it is close to that of an isolated cylinder Ymax /D =0.57;the two downstream cylinders reach their maximum amplitude Ymax /D =0.997 at the reduced flow-velocity Ur =7.9,it is 74.8% larger than that of an isolated cylinder;three asymmetric vibration regions are observed,i.e.,the first asymmetric vibration region is 4.5 10.5;the asymmetric vibration features of the cylinders are closely related to asymmetric wake patterns and stably biased gap flows.%对间距比 s／D ＝5．0正方形顺排排列四圆柱流致振动进行了数值模拟研究，圆柱仅横流向振动，雷诺数为Re ＝100，折合流速为 Ur ＝2．0～50．0。研究发现，上游两圆柱的响应与单圆柱涡激振动相似，呈现出明显的初始分支和下端分支。上游两圆柱的振幅均在折合流速 Ur ＝4．4时达到最大值 Ymax ／D ＝0．56，与单圆柱涡激振动最大振幅 Ymax ／D ＝0．57相近。下游两圆柱的振幅在折合流速 Ur ＝7．9时达到最大值 Ymax ／D ＝0．997，比单圆柱涡激振动最大振幅增大了74．8％。正方形顺排排列四圆柱流致振动响应中出现了三个不对称区间，分别为第一不对称区间4．5＜Ur ＜5．9、第二不对称区间6．9＜Ur ＜7．2和第三不对称区间 Ur ＞10．5。圆柱不对称的振动响应特性和圆柱间隙流稳定偏斜有关。