串列双圆柱涡激振动响应的数值模拟

Numerical simulation on vortex-induced vibration response of two cylinders in tandem arrangements

该文利用动网格技术对雷诺数Re=100的串列双圆柱的涡激振动响应特性进行了详尽的数值研究。研究了上游圆柱固定,下游圆柱横向振动时,不同间距比(L/D=2-5)和折合流速(Ur=2.4-12)对上、下游圆柱的升阻力特性、涡激振动响应特性和圆柱间干扰效应的影响;以及下游圆柱双自由度(横向和流向振动)涡激振动响应特性。研究发现:随着间距比的增大,下游圆柱开始进入"锁定区间"的Ur减小,且下游圆柱的涡激振动对上游圆柱的影响逐渐减弱,但上游圆柱对下游圆柱的干涉效应一直存在。对于不同间距比,在折合流速Ur=7.2附近,下游圆柱的升阻力系数具有很明显的"跳跃"现象,并出现阻力峰值,且不同间距比的下游圆柱都在Ur=7.2时获得最大振幅且幅值相近,这意味着下游圆柱可能在此折合速度下被完全诱导,当下游圆柱被完全诱导振动后,间距比对圆柱振幅的影响较小。不同的折合流速下,小间距比(L/D=2)和大间距比(L/D=5)的尾流会表现出不同的流动形式和"2P"、"2S"等涡脱形式。下游圆柱双自由度振动时,流向振动相对横向振动振幅较小。

Detailed and comprehensive numerical simulation is studied on vortex-induced vibration response of two cylinders in tandem arrangements at Re=100 with the dynamic mesh technique, and aimed at exploring the influence of lift and drag coefficient, The vortex-induced vibration response characteristics and flow structure of two cylinders at different spacing ratios（L/D = 2-5） and different reduced velocities（Ur = 2.4-12） are explored in the case of upper cylinder fixed and downstream cylinder vibration along transverse,and the influence of vibration along flow direction to cross-flow direction when downstream cylinder vibrates freely. The results indicate that the Ur which represents downstream cylinder being locked decreases with the increase of spacing ratio, and the influence to the upper cylinder caused by the vortex-induced vibration of downstream cylinder gradually wanes, but the interference effect of the downstream cylinder to upper cylinder is always present. For different spacing ratios, the lift and drag coefficients of the downstream cylinder jump suddenly and get the drag peak at Ur=7.2.At the same time, downstream cylinder gets the max amplitude. It means that the downstream cylinder may be completely under the conversion speed induction, and after the completely induced vibration, spacing ratio has a little influence to amplitude. Under different reduced velocities, the wakes of small spacing ratio（L/D = 2） and large spacing ratio（L/D = 5） will show different flow and vortex forms such as ＂2 P＂and＂2 S＂.Flow direction vibration has a negligible influence to cross-flow direction when downstream cylinder vibrates freely.