Numerical investigation of bluff body for vortex induced vibration energy harvesting

In order to obtain a larger VIV response and harvest energy more efficiently in wider flow velocity ranges in long-distance transport pipelines, the effects of the elastic modulus of material, mass ratio and cross-sectional shapes (circular cylinder, squa-cir prism, cir-squa prism) of flow-around structure on the VIV performance are numerically investigated in this paper. URANS equations with k-omega SST turbulence model are employed to calculate the two-dimensional flow field with Reynolds number ranging from 2000 to 50000, and Newmark-beta method is adopted to capture the one-degree-of-freedom motion of the system. The numerical results show that the elastic modulus of material and mass ratio are two important factors affecting the natural frequency of the system, which is closely related to the vibration response of system. The range of synchronization increases with an increase in elastic modulus, and the onset of synchronization is more gradual for systems with higher natural frequency. And the maximum amplitude ratio and the range of Reynolds number corresponding to the synchronization region all increase with the decrease of mass ratio. Moreover, the bluff body with squa-cir cross section shows highest amplitude response of 1.16D due to its forward vortex shedding position, indicating the direction for the design of the cross-sectional shapes of bluff body in the pipeline for VIV energy harvesting. Thereby, it can be concluded that the natural frequency of system and vortex shedding position caused by the cross-sectional shapes are important factors affecting the VIV response.