Journal of Shanghai Jiao Tong University

   

Experimental study on vortex-induced vibration response characteristics of a π-shaped jumper in uniform flow outside the plane

  

  1. (State Key Laboratory of Ocean Engineering;School of Ocean and Civil Engineering; Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration;Institute of Polar and Ocean Technology, Shanghai Jiao Tong University,Shanghai 200240,China)

Abstract: As the core component of underwater production facilities, subsea jumpers are likely to encounter vortex-induced vibration (VIV) in the ocean currents, which may lead to fatigue damage to the structure. However, the lack of experimental investigation of the VIV of jumpers resulted in a gap in exploring their VIV response characteristics. To address this gap, an experiment of a π-shaped jumper on VIV is carried out in uniform flow outside the plane with the aim of mechanistic research, and the strain data under different flow velocities are analyzed with common methods such as modal analysis and wavelet transform. It is found that the π-shaped jumper shows the dominant frequency ratios between the in-line (IL) and cross-flow (CF) directions of 3 and 4, differing from that of a single riser in the uniform flow outside the plane. The amplitude of strain in both CF and IL directions follows a variation pattern resembling an inverted quadratic curve under the dominant mode as the flow velocity increases, with peak values in both directions occurring at the same flow velocity.

Key words: π-shaped jumper, vortex-induced vibration, experimental study, strain

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