Research On Flow-Induced Vibration Of Asymmetric Passive Turbulence Control Cylinders Considering Turbulence Intensity

In recent years,many researchers have paid attention to getting energy from ocean current by using Flow-Induced Vibration,and the key is how to further optimize the power generation effect of Flow-Induced Vibration Power Generation Devices.Combining the dynamic grid technology,numerical method with the unsteady RANS method and the Spalart-Allmaras turbulence model are used to realize the exchange of fluid and solid information by writting program codes on the secondary development platform of Fluent in the paper,and the parallel rewriting of program codes is further realized.Parallel numerical computation in Flow-Induced Vibration of single cylinder and tandem double cylinders with asymmetric roughness strip is realized.There are many factors affecting the Flow-Induced Vibration of single cylinder and tandem double cylinders with asymmetric roughness strip,and the paper considers Reynolds number,inlet turbulence intensity,system damping ratio and spacing ratio.The research content includes the amplitude ratio,amplitude deviation ratio,frequency ratio,lift-displacement phase difference,displacement phase difference,wake vortex mode and power generation et al.The main conclusions are as follows: the positive and negative amplitudes of single cylinder and upstream cylinder with asymmetric roughness strip are different,and the negative amplitudes are smaller.With the increase of inlet turbulence intensity and system damping ratio,the amplitude of single cylinder and upstream cylinder with asymmetric roughness strip decreases.The vibration is stabilized and the vibration deviation phenomenon is weakened with the increase of inlet turbulence intensity and system damping ratio.For the downstream cylinder with asymmetric roughness strip,the vibration deviation phenomenon of upper branch is eliminated,and the deviation phenomenon of upper-galloping transition branch and galloping branch is weakened.The spacing ratio and inlet turbulence intensity can not cause significant changes in lift-displacement phase difference between single cylinder and tandem double cylinders with asymmetric roughness strip,but the lift-displacement phase difference increase with the increase of system damping ratio.The vibration frequency ratio of the upstream and downstream cylinders with asymmetric roughness strip is inconsistent in the initial branch and the upper branch.With the increase of Reynolds number,the number of wake vortices of the single cylinder and upstream cylinder with asymmetric roughness strip increases,and the wake patterns of 2S,QP+P,2P+2S,unstable 2T,2T,2T+S and 2T+2S appear in turn.A new pattern Double-S(DS)of the single cylinder and the upstream cylinder is found at Re=60000.But the wake pattern of downstream cylinder are difficult to identify at small spacing ratio.When wake vortices of the upstream and downstream cylinders with asymmetric roughness strip move downstream,the vortices in the same rotation direction attract each other and converge finally.The increase of inlet turbulence intensity leads to the elongation of wake vortices of the single cylinder and tandem double cylinders with asymmetric rough strip,and the wake pattern becomes unclear.With the increase of system damping ratio,the wake vortices of single cylinder and tandem double cylinders with asymmetric roughness strip become smaller,which makes the wake vortices dissipate faster.Within the parameters studied in this paper,the power generation and efficiency of the single cylinder and the upstream cylinder with asymmetric roughness strip increase with the increase of system damping ratio.But for the downstream cylinder,its power generation effect is suppressed,and with the increase of system damping ratio,the suppression effect is more obvious.