并列刚性双圆柱流激振动风洞试验研究

Wind tunnel test study on flow-induced vibration of parallel dual-rigid cylinder

通过风洞试验研究了弹性支撑条件下并列刚性双圆柱的流激振动,试验雷诺数范围Re=3200~36200。圆柱间距比S/D=1.5~4.0,其中S为两圆柱圆心间距,D为圆柱直径。结果表明:随着间距的变化,并列双圆柱的振动幅值呈现涡激振动(vortex-induced vibration,VIV)和尾流耦合涡激振动(wake-coupled vortex-induced vibration,WCVIV)模式。WCVIV发生在间距比S/D≤3.0时,此时双圆柱之间相互干涉作用较强,双圆柱振动幅值响应呈现不一致性,振动位移之间表现为同相位或反相位耦合特征,圆柱尾流场对称点的涡脱频率也不相同,尾流呈现不对称性。而VIV发生在间距比S/D=3.5~4.0时,此时双圆柱相互独立,其振动幅值和涡脱频率几乎相同,尾流的不对称现象消失,振动位移之间相位差不再近似等于恒定值而是随时间周期性的“划动”。无论发生WCVIV还是VIV,振动频率的主频均锁定于1倍的固有频率。

Here,flow-induced vibration of parallel dual-rigid cylinder with elastic supports was studied with wind tunnel tests.In tests,Reynolds number range Re=3200-36200,cylinder spacing ratio S/D=1.5-4.0 where S is the distance between centers of two cylinders and D is the diameter of two cylinders.The results showed that with changes of S/D,vibration amplitudes of parallel dual-cylinder present two modes of vortex-induced vibration(VIV)and wake coupled vortex-induced vibration(WCVIV);WCVIV occurs when S/D≤3.0,at this time,interaction between two cylinders is stronger,vibration amplitude responses of two cylinders are inconsistent,vibration displacements reveal in-phase or anti-phase coupled feature,vortex shedding frequencies at symmetrical points in cylinder’s wake field are also different,and wake is asymmetric;VIV occurs when S/D=3.5-4.0,at this time,two cylinders are independent of each other,their vibration amplitudes and vortex shedding frequencies are almost the same,wake asymmetry disappears,and phase difference between two cylinders’vibration displacements is no longer approximately equal to a constant value,but periodically“scratches”with time;whether WCVIV or VIV occurs,the main frequency of vibration frequencies is locked at 1 times cylinder’s natural frequency.