Effect of Geometrical Parameters on Vortex-Induced Vibration of a Splitter Plate

An experimental study on the effects of various geometrical parameters to the characteristics of vortex-induced vibration (VIV) of a splitter plate is presented. The dynamic response of the fluid-structure system was measured using particle image velocimetry and laser telemetry simultaneously. Combined data of these techniques allow the assessment of the variation in the VIV response due to geometrical parameters, such as channel geometry, aspect ratio (AR), and trailing-edge thickness $(d)$ as well as the imprint of the excited vibration mode on the flow. The effects of AR and $d$ were both investigated with three different plate geometries and the effect of channel convergence was studied with a single plate geometry. Measurements were performed over a range of Reynolds numbers (Re). The results show that the vibrational response of the combined fluid-structure system is affected by the VIV instability in all cases. Within the measured Re range, a characteristic stepwise behavior of the frequency of the dominant vibration mode is observed. This behavior is explained by the synchronization between the vortex shedding frequency $(f0)$ and a natural frequency $(fN)$ of the fluid-structure system. The results further indicate that this response is modified by geometrical parameters. Channel convergence, i.e., flow acceleration, enhances the vortex shedding, which, in turn, increases the excitation level leading to stronger VIV. Channel convergence does not have a significant effect on $f0$ or on the dimensionless vibration amplitude $(A∕d)$⁠. An increase of both the number of excited $fN$’s and the level of synchronization was observed with the lowest AR case. The results also suggest that $d$ is the dominant geometrical parameter. It reduces both the $A∕d$ of the plate and the number of synchronization regions. This stronger effect on the response of the VIV system is due to the direct effect of $d$ on the excitation mechanism.