Destabilizing damping effect on flat-plate vibrations due to flow-induced flutter

This paper discusses a case of destabilizing contribution of damping, observed for a flat-plate model vibrating in the cross-flow direction (heaving) and in the rotational degree of freedom (pitching) due to the flow-induced classical-flutter instability. This aeroelastic system can be employed in energy-harvesting applications, where the power extraction corresponds to an equivalent mechanical damping in the heaving motion component. The damping influence was investigated through parametric linear analyses and wind-tunnel tests, discussing the features of both the instability threshold and the system response in the post-critical regime of oscillation. For specific sets of the governing parameters, high-damped configurations get unstable earlier compared to the low-damped case, and show a post-critical motion characterised by a larger pitching amplitude and a pitching-to-heaving phase close to the quadrature.