Numerical study on the flow-induced rotation coupled with vortex-induced vibration of a cylinder with Savonius impeller structure

A novel cylindrical energy conversion device with Savonius impeller structure was numerically simulated, incorporating user-defined functions and the SST k-a> turbulence model to achieve the analog of fluid-structure coupling. The flow rotation and vibration response of the cylinder with Savonius impeller structure of different ellipticities were investigated. The mechanism of coupling between flow rotation and vortex-induced vibration was revealed. The results show that the impeller structure ellipticity is the key to influence the transverse flow displacement of the cylinder. For cylinders with the same ellipticity, the projected area is an important factor affecting the downstream displacement. At low reduction velocities, the cylinder rotates unsteadily, forming an asymmetric flow wake, and showing a P + S wake pattern. At high reduction velocities, the cylinder rotates steadily in the clockwise direction, and the rotational angular velocity fluctuates periodically. In an identical rotation period, cylinders with smaller impeller structure ellipticities exhibit larger absolute values of the cylinder' s instantaneous torque coefficient. © 2024 Chinese Vibration Engineering Society. All rights reserved.