FIV characteristics of a vibrational cylinder with a tail fin behind an inverted D-section interfering cylinder

Abstract

Wake-induced vibration (WIV) is common in engineering and may cause structural damage. The application of bionic devices in vibration control has attracted much attention, but most studies focus on isolated system and pay insufficient attention to the response under wake interference, which limits their application in engineering. Therefore, it is crucial to better understand the interaction between flow and bionic devices under wake interference. Inspired by the tail fin structure of fish tail, this paper studies the hydrodynamic characteristics of an elastically mounted cylinder with a tail fin in the wake of an inverted D-section cylinder. By changing the distance between the two centers of the circle and the length of the tail fin, the amplitude, frequency response and the mechanism of wake-induced vibration are explored. The results indicate that as the spacing ratio (L / D) increases, the WIV of the cylinder with a longer tail fin is excited. When WIV occurs, the phase difference (Φ) between the hydrodynamic coefficient and the transverse displacement experiences two jumps, and the lock-in bandwidth is wider compared with the single cylinder. As the tail fin length increases, the transverse lock-in frequency ratio yosu (f_yosu / f_n) decreases. Additionally, vortex shedding from the upstream inverted D-section cylinder (UIDC) affects the surface pressure distribution and vortex shedding characteristics of the downstream cylinder with a tail fin (DCTF). An analysis of the energy transfer reveals that the direction of transmission between the energy transfer and cylinder motion affects the amplitude response.