Numerical investigation of flow-induced vibration suppression for the circular cylinder via counter-rotating control rods in the wake region

This article discusses the influence of control rods on the main cylinder through numerical methods. Control rods were symmetrically arranged in the wake region of the main cylinder for counter rotation. Six operating conditions (P0-P5) were compared within the flow velocity range of Ur = 2-14 ( Re = 0.8 × 10 4 - 5.6 × 10 4 ) . These operating conditions cover bare cylinder, zero rotational speed, reduced rotational speed ( ? = 0.8 and ? = 2), and positive and negative rotational direction modes. This article analyzes the influence of amplitude response, frequency characteristics, trajectory, and wake evolution of flow induced vibration systems under different conditions. The results indicate that control rods can effectively control the vibration of the system. Compared with the bare cylindrical working condition P0, the vibration suppression effect of negative rotational direction P2 is limited in the low reduced velocity range. By changing the rotational direction P1, reducing the rotational speed to zero P3, or increasing the rotational speed P5, efficient vibration suppression was achieved. The mechanism stems from the jet effect formed by the gap, which leads to the attenuation of the negative pressure area in the wake. After increasing the reduced velocity, zero rotational speed P3 is no longer competitive in vibration suppression. However, both positive rotational direction P1, P4 and negative rotational direction P5 can suppress vibration. The mechanism stems from reducing the strength of the negative pressure zone at the tail of the main cylinder. In addition, increasing the rotational speed can reduce the sensitivity of vibration to the direction of control rods rotation.