Experimental investigation of the effect of the wall proximity on the mode transition of a vortex-induced vibrating flexible pipe and the evolution of wall-impact

作     者：Hong-jun Zhu Hong-lei Zhao Yi-pu Xie Xu Zhang 

作者机构：State Key Laboratory of Oil and Gas Reservoir Geology and ExploitationSouthwest Petroleum UniversityChengdu610500China 

出 版 物：《Journal of Hydrodynamics》 (水动力学研究与进展B辑（英文版）)

年 卷 期：2022年第34卷第2期

页      面：329-353页

核心收录：

学科分类：08[工学] 080103[工学-流体力学] 0801[工学-力学（可授工学、理学学位）] 

基　　金：supported by the National Natural Science Foundation of China(Grant No.51979238). 

主　　题：Wall proximity oblique flow wall impact mode transition vortex-induced vibration(VIV) 

摘      要：The present work experimentally investigates the vortex-induced vibration(VIV)and the pipe-wall impact of a flexible pipe in an oblique flow.The flexible pipe with an aspect ratio of 86.67 and an oblique angle of 30°is immersed in the water flow with the initial gap ratio in the range of 0.2–0.8 and 49.5.The space-time varying oscillation responses in both the in-line and cross-flow directions are recorded using the non-intrusive optical measurement with high-speed cameras in the normal reduced velocity range of 3.40–14.43.The oblique flow induces the spatial variations of the inclination angle to the flexible pipe as a result of the bending deformation during the oscillation.Consequently,the flexible pipe experiences an asymmetrical response along the span and an out-of-sync mode transition in the in-line and cross-flow directions.As the gap ratio decreases,the VIV response is suppressed,and the vibration regions of lower modes are prolonged with the result of the delay of higher excited modes.Additionally,the wall proximity results in an upward deflection of the equilibrium position,and this offset is enlarged with the decrease of the gap ratio.The occurrence of the pipe-wall impact depends on the amplitude of the spatial-temporal varying oscillation and the dominant response mode.Five pipe-wall impact patterns are proposed in terms of the number and the length of the contact pipe segments.The evolution of the pipe-wall impact pattern with the increase of the normal reduced velocity is closely related to the variations of the dominant response mode and the amplitude and the alteration of its spatial distribution.