Numerical Analysis Of Flow Around Elastic Pipe Under Shear Flow

Pipe(Pipe array)system is widely used in steam generator,bridge engineering and deep-sea engineering.The dynamic problem of pipeline may directly affect the safety of the whole engineering system.The real flow field in nature is mostly in the form of shear flow,so the research on the pipe(Pipe array)structure under the shear flow is of great significance and value,which needs to be further analyzed and studied.Based on the ANSYS Workbench platform,this paper applies the bidirectional fluid-solid coupling method,the models of single pipe and equilateral three pipe under transverse shear flow in low Reynolds number environment were established respectively,and the response of the system under different shear rates and pipe spacing was calculated.It mainly includes the following contents.Based on the background of bridge cables and submarine pipelines,this paper studies the flow around elastic pipes with fixed ends under transverse shear flow.The response of pipeline system under transverse shear flow is calculated and analyzed.Explores the Influence of shear rate on elastic pipe vibration,It is found that different shear rates have a great influence on the lift coefficient,the trajectory of the single-pipe structure under the Reynolds number of 150 is in the shape of "8".It is found from the time-history diagram of the y-direction displacement of each monitoring point that the change of shear rate has a great influence on the structural response of the single elastic pipe.It can be seen from the vorticity diagram that the Drain vortex mode of single pipe is mainly 2S mode at 150 Reynolds number,with the increase of shear rate,the vorticity intensity of the whole flow field increases gradually,when the shear rate is large,the strength of vortex street in the flow field increases gradually,and the strength of lower vortex street decreases gradually.The velocity distributions along different sections of the wake area of a circular pipe are very different and show obvious three-dimensional characteristics.Through One cycle of motion fluid-solid coupling interaction,the dynamic characteristics of shear flow VIV vortex are revealed.Through a period of fluid-solid coupling interaction,the dynamic characteristics of shear flow VIV vortex are revealed.Based on the application background of submarine cables and submarine multi-pipeline systems,The influence of tube spacing on the vortex shedding phenomena of the two tubes was investigated.The influence of shear rate on the structural response of two vertical tubes was investigated.It is found that the variation of pipe spacing has great influence on the lift coefficient curves of pipes 1 and 2 and the main frequency and main frequency amplitude of lift coefficient curves.The main frequency of lift coefficient of pipe 1 decreases first and then increases,and the main frequency amplitude of lift coefficient increases continuously.The main frequency of lift coefficient increases gradually,and the main frequency amplitude of lift coefficient decreases first and then increases.The Y-direction displacement amplitude of the monitoring point in the middle section of pipe 1 increases gradually.The y-direction displacement amplitude of the monitoring point in the middle section of pipe 2 increases first and then decreases.The effect of pipe spacing on the vortex shedding of two pipes was investigated.Further,based on the analysis of the flow around the vertical double elastic pipes,the vortex-induced vibration characteristics of the three-pipe model are investigated by studying the flow around the three-pipe model.In general,The influence of shear rate on the structural response of three-pipe model with equilateral edges is analyzed.The variation of the spacing of three pipes has a great influence on the lift coefficient curve.The amplitude of lift coefficient increases gradually from 2.5D to 4.5D,and decreases gradually after 5.0D.The amplitude of the middle section of pipe E in the Y direction reaches its maximum at the distance of 4.5D,and the amplitude in the Y direction of pipe E is obviously higher than that of the upstream two pipes.The main frequency of lift coefficient increases gradually to a fixed value,and the main frequency amplitude increases first and then decreases.The overall trend is basically the same as that of the monitoring point.Under the influence of shear flow,the vorticity intensity on the upper side of the flow field is greater than that on the lower side.In the case of small spacing ratio,the eddy discharge mode of pipe C is influenced by downstream pipe E,and a single eddy S mode is formed on the upper side of the pipe.When the spacing ratio increases,it changes to 2S mode,and the vortex begins to appear on the lower side of pipe C.Pipe D is initially a single-row vortex street S mode,and evolves into a double-row vortex street 2S mode with the increase of pipe spacing.Pipe E is initially a single-row vortex street P mode,and evolves to 2S mode with the increase of pipe spacing.At the same time,the velocity and pressure distributions in the wake region of a circular pipe are not the same along different sections.At this time,the flow field presents obvious three-dimensional characteristics.