An experiment study of vortex induced vibration of a steel catenary riser under steady current

The vortex induced vibration(VIV)of marine risers has been investigated by many researchers in experimental studies of a straight flexible riser model as well as a rigid cylinder to reveal the dynamic response characteristic and the mechanics behind it.However,due to the limitation of experimental apparatus,very few studies are about the VIV of a steel catenary riser(SCR)which is with a complex geometry.To investigate the VTV features and to further develop the corresponding numerical predictions of a SCR under steady current,a large-scale model test of a SCR was towed in an ocean basin at various speeds.Fiber Bragg grating strain sensors are instrumented on the riser model to measure both in-plane and out-of-plane responses.The characteristics of oscillating amplitude and dominating frequency response,the phenomenon of mode competition and travelling wave and the fatigue damage of the steel catenary riser in inline and cross-flow direction under steady current are analyzed.