Oscillation responses and mechanisms of three rigidly coupled circular cylinders
LIU Xufei1,CHEN Weilin2,JI Chunning2
1. School of Water Conservancy and Environmental Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou 310018, China;
2. State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China
Abstract:This paper numerically investigated the flow-induced vibration of three rigidly coupled cylinders by using the iterative immersed boundary method. The three cylinders are in equilateral-triangular arrangements with two side-by-side cylinders upstream and one cylinder downstream. The spacing ratio of the cylinders is P/D = 1.0-4.0, the Reynolds number is Re = 100, the mass ratio is m* = 2, and the reduced velocity is Ur = 3.0-30.0. Variations of the vibration amplitude, the vibration frequency and the hydrodynamic forces of the cylinders with the reduced velocity are investigated. Two vibration modes are found, and they are the galloping mode at a small spacing ratio (P/D = 1.0) and the vortex-induced vibration mode at a medium to a large spacing ratio (P/D = 1.6-4.0). Under the conditions with different spacing ratios, the vortex-induced vibration vibration shows distinct features, i.e. the single lock-in region at P/D = 1.6 and double lock-in regions at P/D = 2.5-4.0. By further investigating the wake patterns, it is found that in the first lock-in region (also in the single lock-in region), the vibration is excited by the shear-layer reattachment, while in the second lock-in region, the vibration is provoked by the alternate vortex-shedding from the cylinders.
刘旭菲1,陈威霖2,及春宁2. 刚性耦合三圆柱流致振动特性和机制[J]. 振动与冲击, 2022, 41(12): 1-7.
LIU Xufei1,CHEN Weilin2,JI Chunning2. Oscillation responses and mechanisms of three rigidly coupled circular cylinders. JOURNAL OF VIBRATION AND SHOCK, 2022, 41(12): 1-7.
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