Numerical Simulation Study On Mutual Influence Mechanism Of Tandem High Damping Double Cylindrical Flow Vibrating Vibration

The global economy is undergoing rapid development In order to meet the needs of economic development,countries around the world are constantly looking for renewable and clean energy that can replace traditional fossil energy.Professor Bernitsas of the University of Michigan in the United States proposed a flow-induced vibration water kinetic energy conversion device in 2006,which can generate a large amplitude of vibration at a lower flow rate and drive the generator to generate electricity,so it can be applied to For a wide range of waters.In an actual flow-induced vibration power generation field,in order to achieve a certain scale,it is necessary to arrange a plurality of column devices under water to form an array of devices.In this paper,the simplest configuration of the cylinder array,namely the double cylinder case,is studied.The numerical simulation is used to study the interaction between the cylinders in the process of series double-column flow vibration under different arrangement intervals,and a reasonable column is sought.The arrangement of the spaces allows the cylindrical array to obtain greater vibrational energy at lower flow rates and increase the energy density of the column array.Considering the complexity of the problem and in order to better separate the various influencing factors,the upstream or downstream cylinders are first fixed to study the influence of the presence of upstream or downstream fixed cylinders on the flow vibration of the downstream or upstream cylinders,and then The upstream and downstream cylinders can be freely vibrated to study the interaction of the two cylinders.Therefore,this paper numerically simulates the following three configurations of tandem double cylinders:1)the upstream cylinder is fixed,the downstream cylinder is free to vibrate;2)the downstream cylinder is fixed,the upstream cylinder is free to vibrate;3)the upstream and downstream cylinders are free to vibrate.Based on the continuous equation and the Reynolds average NS equation,combined with the SST k-? turbulence model,the flow field around the cylinder is simulated.The finite volume method is combined with the ALE dynamic mesh following technique to mesh the computational domain,and at the same time,to prevent the cylinder in the calculation process.When the large motion is generated,the flow field grid between the double cylinders is excessively deformed,which leads to the calculation impossible.The regional block technique is used to divide the whole calculation domain into different blocks.Meshing.In order to better simulate the vibration characteristics of the cylinder during energy conversion,the calculation uses high damping ratio and high Reynolds number.The calculation results show that the existence of the upstream or downstream cylinder has a great influence on the cylindrical flow vibration.The difference of the amplitude curve is mainly related to the spacing ratio and the configuration of the double cylinder.When there is a fixed cylinder in the upstream,the amplitude curve of the downstream cylinder has three kinds of vortex-induced vibration,galloping,and separated vortex-induced vibration amplitude curves.In the other two configurations(the downstream cylinder is fixed,the upstream cylinder is free to vibrate;the upstream and downstream cylinders are free to vibrate),the cylindrical amplitude curve exhibits only a vortex-induced vibration curve.In the three configurations of a tandem double cylinder,the amplitude is improved relative to a single cylinder,and the maximum amplitude ratio of the cylinder is 2.3D.When the spacing between the cylinders is small(spacing S=1.5D and 2.0D),the eddy energy dissipation after the upstream cylindrical vortex shedding is lower,which has a greater influence on the downstream cylinder,and the interaction between the cylinders is enhanced.The amplitude of the downstream cylinder is greatly improved.When the pitch is gradually increased to 3.0D and 4.0D,the wake pattern of the upstream cylinder becomes very unstable as the reduction speed increases.In the case of the upstream cylinder fixed,when the reduction rate is near 9.0,the shear layer of the upstream cylinder directly adheres to the downstream cylinder,and there is no vortex shedding.At this time,the downstream cylinder is in a high-frequency ultra-low amplitude vibration response state.In the case where both the upstream and downstream cylinders vibrate,when the reduction velocity U>13.5,the upstream cylindrical vibration causes the wake between the tandem double cylinders to be unstable,so that the displacement time history curve of the downstream cylinder is irregular.As the spacing between the cylinders continues to increase to 20.0D,the vortex energy in the shedding vortex gradually decreases.At this time,the double cylinder flow vibration response is weakened,the cylindrical lift and amplitude are reduced,and the vibration of the upper and lower cylinders is reduced.The curve becomes a vortex-induced vibration curve,but the wake of the upstream cylinder still affects the downstream cylinder,resulting in the amplitude of the downstream cylinder being greater than the amplitude of the cylinder in the case of a single cylinder.