Fluid-Structure Interaction Exciting Mechanisms of Flexible Structures in Uniform Flows

The oscillation of a structure immersed on a flow can become self-excited as a result of different fluid-structure interaction mechanisms. To identify the self-exciting mechanisms and to understand the influence of the physical parameters on the different exciting processes, the two-dimensional free swivelling movement of flexible structure models were investigated in both laminar and turbulent uniform flows. The coupled fluid and structure movement was characterized using a particle image velocimetry (PIV) system complemented by a time-phase detector to obtain accurate time-phase resolved measurements of the flow velocity field and structure deformation. The experimental tests proved that the self-exciting mechanisms are strongly dependent on the approaching flow velocity. For the velocity range tested, a sequence of clearly defined movement-induced excitation (MIE) and instability-induced excitation (IIE) of the model was observed on increasing the velocity of the incoming flow. In this contribution, the results for one specific structure configuration are presented.