Author(s): Di Zhang, Yakun Liu

Linked Author(s): Di Zhang, Yakun Liu

Keywords: Flow-Induced Vibration; Vibration Mechanism; Vortex-Shedding Frequency; Flow Regimes; Mass-Damping Parameter;

Abstract: This study carries out an in-depth summarization and analysis of the flow-excited vibration mechanism for the prisms of circular or rectangular section. It is well-known that when the natural vibration frequency of the prism is close to the vortex-shedding frequency, the dependent interaction of the vortex-shedding along the prism axis is remarkably strengthened. At this moment, the vortices are uniformly released along the whole span of the prism, the vortex excitation force is magnified, and the vortex-shedding frequency is synchronized with the vibration frequency of the prism. This study investigates three kinds of vortex-shedding mechanism of the rectangular prism, namely the Leading-Edge Vortex Shedding (LEVS), the Impinging Leading-Edge Vortices (ILEV) and the Trailing-Edge Vortex Shedding (TEVS). Further, this study summarizes the relationship between the vortex-shedding frequency fs and the parameter e/d (where e and d are the lengths of the prism along the streamwise and tranverse directions, respectively.) and the attack-angle α for three types of prismatic grid-bar (viz. the rectangular section, that with a semicircular leading edge, and that with semicircular leading/trailing edge). In addition, this study analyzes the relationships between the lateral vibration amplitude y0, the torsional vibration amplitude θ0, the value of e/d, the mass-damping parameter δc and the inducing velocity Vr for the flow field with a relatively low turbulence intensity.

DOI: https://doi.org/10.3850/38WC092019-0436

Year: 2019