Experimental Study On Wing Shaped Vortex Induced Vibration Suppression Device Installed On Riser Based On Bionics

Riser is an indispensable part of offshore drilling and production.It not only has to bear self-weight and top tension,but also bear the coupling effect of external marine environment load,drill string and drilling fluid.When the current flows through the riser,the fluid will separate from the boundary layer of the outer wall of the riser and generate low pressure and vortex behind the riser.The periodic vibration of the riser caused by the vortex shedding is called vortex induced vibration.When the frequency of vortex shedding is close to the natural frequency of the riser,there will be a "locking" phenomenon.Once the "locking" phenomenon occurs,the degree of deformation,stress,bending moment and fatigue damage will also increase significantly,which will have a great impact on the structure.At present,many scholars at home and abroad have made deep research on vortex shedding mechanism of deep water drilling risers and reduced and prevented vortex induced vibration,and some achievements have been achieved.This paper on the basis of previous studies,based on the suppression effect of vortex induced vibration suppression device,starting from the vortex shedding mechanism of vortex induced vibration,this paper studies the inhibiting law device has suppression of vortex induced vibration,According to the bionics principle,a new device based on bionics is designed,which is used to suppress the vortex induced vibration of the wing riser.The experimental research on the self-made simulated ocean current experiment device with particle image velocimetry(PIV)technology is carried out.The flow state around the pipe column model of the riser and the pipe column model with the suppressor is studied experimentally.It is proved that the suppressor has an inhibitory effect.The flow state around the column device is provided with a wing shaped model of inhibition of the ribbon and the column model with ordinary ribbon the suppression device is studied experimentally.Through the analysis and comparison of suppression devices and with ordinary ribbon column model experimental results,verify the VIV suppression device with wing shape ribbon has better inhibitory effect.The main structural parameters characteristics(the length of ribbon shaped wings,the arc of the wings,the number of arcs of the wing)of the vortex induced vibration suppression device for the feathers are experimentally investigated.Research shows that: the length and shape of the ribbon curved wings wings influence on inhibition action of the Suppressor,and the circular arc feathers have more inhibitory effects on them,but the number of wing arcs has little effect on the inhibition of the suppressor.