双圆柱绕流诱发振动的数值模拟(Part I横向振动)

Numerical simulation of flow-induced vibration on two circular cylinders in a cross-flow(Part Ⅰ: transverse y-motion)

采用任意拉格朗日-欧拉(ALE)方法数值模拟圆柱在尾流中的流体诱发振动特性。重点分析了圆柱的动力学响应特性,包括升阻力、位移振幅、拍和锁定等现象;另外也详细分析了圆柱的尾涡结构。研究结果表明,在串列下,大质量比时,圆柱的振动会受到抑制,小质量比时,圆柱的振动则会被放大;较之孤立柱的情形,圆柱共振发生在低于且接近于1.0的频率比带内且不易随质量比的变化发生偏移;小质量比下圆柱振幅及共振带都要比大质量比下的大得多;不同频率比和间距比下,圆柱的动力学特性存在明显的差异,相应的涡脱落模态呈现出2P、P+S和2S模态甚至是2P+S模态,各种模态之间互相竞争促进流固耦合的不断变化发展,导致涡间距和涡街宽度的变化。

Flow-induced vibration on a circular cyilnder in a wake has been studied by numerical solutions using Arbitrary Lagrangian-Eulerian（ALE） method. One of the emphases was on the dynamic responses of the circular cylinder including forces, amplitude of displacement, beating and lock-in phenomena. Another emphasis was on the vortex structures in the wake of the circular cylinder. The presented results show that （a） in the tandem arrangement, flow-induced vibration of the circular cylinder＇is greatly suppressed when the mass ratio is high while amplified When the mass ratio is low, （b） the resonance band of the cylinder not shifted with the variation of the mass ratio occurs at the frequency ratios which are lower than unity but close through the comparison with that of an isolated cylinder, （c） the amplitude and resonance band of the cylinder response are much larger at low mass ratio and （d） distinct features of the dynamics response on the cylinder are investigated including corresponding vortex patterns which appear many typical modes, 2P, P ＋ S and 2S, even 2P ＋ S mode with various frequency ratios and spacing ratios. These various modes play a drastic competition to advance the interaction between the fluid and structure, thus leading the changes of the spacing separation between vortices and the width of the vortex street.