Study On The Design Of Detached Splitter Plate For Suppressing Vortex Induced Vibration Of Cylinder

With the advancement of the marine development strategy,in the marine environment where engineering application conditions are always deteriorating,how to minimize the structural damage caused by the vortex-induced vibration of marine risers,column legs and other structures in the marine environment It has become the focus of research,so it is very necessary to carry out the simulation design of the downstream separated splitter plate for cylindrical vortex-induced vibration suppression based on the two-dimensional numerical simulation method to obtain an effective vortex-induced vibration suppression program.The first task of the research is to clarify the characteristics of the results obtained by the two-dimensional numerical simulation for cylindrical vortex-induced vibration and the differences between the results and the experimental results.Therefore,based on the SST k-ωturbulence model and the fourth-order Runge-Kutta algorithm,the two-dimensional numerical simulation of the vortex-induced vibration response of a bare cylinder is carried out.First,the low-Reynolds number cylinder single-degree-of-freedom vortex-induced vibration calculation is performed on the two-dimensional numerical calculation.The reliability of the frame is verified,and on this basis,the calculation and analysis of the vortex-induced vibration response of a medium Reynolds number cylinder with two degrees of freedom are completed.The analysis results show that the results of the cylindrical lateral amplitude and wake shape at low Reynolds numbers are in good agreement with the experimental data,which indicates the reliability of the two-dimensional numerical simulation calculation framework.However,under the medium Reynolds number,the horizontal and downstream vibration amplitude changes of the cylinder cannot be well matched with the experimental results.The downstream vibration is not enough to compensate for the lack of random disturbances,resulting in the dual-degree-of-freedom numerical simulation results that cannot be matched with the experimental results.The amplitude response.The vorticity distribution under each branch condition calculated by numerical simulation corresponds well to the experiment,especially the special "2T" form wake vortex is also well captured,which means it can be used for further manifold simulation Design research.Next,a single fixed flow rate is selected and the control variable method is used to study the vortex-induced vibration suppression effect of the separated rigid splitter plate.When a single splitter plate is used,the distribution pitch and plate thickness have a clear range of effective values,and when the splitter plate length increases within a certain range,the vibration suppression effect will continue to improve.When using dual splitter plates,parallel dual splitter plates are not an effective means of vortex-induced vibration suppression,and changes in the spacing between the plates cannot achieve better vibration suppression effects than single splitter plates with the same parameters.However,when the arrangement angle is increased,the suppression effect of the double splitter plate on the lateral vibration of the cylinder is further improved than that of the single splitter plate,but the suppression of the downstream vibration of the cylinder at this time has deteriorated and unstable performance.After selecting multiple groups of different flow rates,it is found that the double splitter plate can provide more effective lateral vibration suppression effect than the single splitter plate in the middle and low flow rate stages,but the single splitter plate has more advantages for downstream vibration control.At the same time,both schemes lose their lateral vibration suppression effect during the high-speed stage,and fail at lower flow rates in the downstream direction.Therefore,when applied under actual offshore engineering conditions,the parameter settings of single and double splitter plates and the use process need to be evaluated and used according to specific sea conditions.