Splitter plates have been recognized as useful passive devices to reduce drag, mitigate flow-induced vibration, and enhance heat transfer efficiency of a circular cylinder. However, undesired torsional flow-induced vibrations due to splitter plate attachment require further investigation. This paper numerically studies the flow-induced torsional vibrations of an elastically mounted circular cylinder with an attached splitter plate in laminar flow with a Reynolds number of 100. A finite volume formulation is utilized to solve the incompressible two-dimensional fluid governing equations. Torsional vortex-induced vibrations (VIVs) are observed at lower reduced flow velocities, while a symmetry-breaking bifurcation occurs as the reduced flow velocity increases, after which the cylinder-plate assembly vibrates around a nonzero equilibrium angle. The numerical results show that the synchronization range of VIV extends, the peak VIV amplitude increases, and the critical reduced flow velocity for the bifurcation decreases with decreasing the moment of inertia. The symmetry-breaking bifurcation is due to a combined effect of the structural restoring moment and the flow-induced moment. The critical reduced velocity of the bifurcation and the nonzero equilibrium angle at any reduced velocity can be calculated based on the mean moment coefficients of the cylinder-plate assembly. The flow-induced moment is mainly induced by the pressure difference between the splitter plate's upper and lower surfaces. The phase difference between the torsional moment and displacement is 0° at lower reduced velocities, while the phase difference jumps to 180° at a reduced velocity of approximately 6.5. The mean drag coefficient of the vibrating cylinder-plate assembly is lower than the mean drag coefficient of a stationary circular cylinder but often higher than that of a stationary cylinder-plate assembly. The dominant frequency of the drag force is twice the vibration frequency before the symmetry-breaking bifurcation, while the dominant frequency becomes consistent with the vibration frequency after the bifurcation. The typical 2S mode of vortex shedding is identified for all considered moments of inertia and reduced flow velocities. However, the timing of a non-shedding vortex changes at the critical flow velocities for the phase jump and symmetry-breaking bifurcation. The observed torsional vibrations suggest that circular cylinders with splitter plate attachments may be competitive candidates for VIV-based energy harvesting, while they may not be good choices for heat exchangers.

分流板已被公认为有用的被动装置，可减少阻力、减轻流动引起的振动并提高圆柱体的传热效率。然而，由于分流板附件引起的不希望的扭转流引起的振动需要进一步研究。本文数值研究了在雷诺数为 100 的层流中弹性安装的带有分流板的圆柱体的流动引起的扭转振动。利用有限体积公式来求解不可压缩的二维流体控制方程。在较低的降低流速下观察到扭转涡旋引起的振动 (VIV)，而随着降低的流速增加，发生对称破坏分叉，之后气缸板组件围绕非零平衡角振动。数值结果表明，随着转动惯量的减小，VIV的同步范围扩大，VIV峰值幅度增大，分叉处临界减小流速减小。对称破坏分岔是由于结构恢复力矩和流动诱导力矩的共同作用。分岔的临界减速度和任何减速度下的非零平衡角都可以根据气缸板组件的平均力矩系数计算。流致力矩主要由分流板上下表面的压力差引起。扭矩和位移之间的相位差在降低速度较低时为 0°，而在降低速度约为 6.5 时相位差跃升至 180°。振动气缸板组件的平均阻力系数低于静止圆柱体的平均阻力系数，但通常高于静止气缸板组件的平均阻力系数。阻力的主频率是对称破坏分叉前振动频率的两倍，而主频率与分叉后的振动频率一致。涡旋脱落的典型 2S 模式是针对所有考虑的惯性矩和降低的流速确定的。然而，非脱落涡旋的时间在相位跳跃和对称破坏分岔的临界流速处发生变化。观察到的扭转振动表明带有分流板附件的圆柱体可能是基于 VIV 的能量收集的竞争候选者，