Diagnosis of vortex induced vibration of a gravity damper

Abstract

A gravity damper is a one-way valve, employed for regulating the airflow rate in ducts, generally constituted by a series of rectangular panels (closure sections), connected to an articulated quadrilateral synchronizing the movements. If the device needs to process large masses of high speed air, as common in the case of energy conversion systems, disadvantageous dynamic effects can occur. In this study, vortexinduced vibration (VIV), occurring on a gravity damper for high values of the Reynolds number, is investigated. The analysis of this work couples numerical methods (Computational Fluid Dynamics with Large-Eddy Simulation turbulence model and Finite Element Method) to experiments: a full-scale accelerometric measurement campaign is actually performed at the wind tunnel facilities of the University of Perugia. VIVs are diagnosed and quantified through the experimental vibration analysis, which is interpreted through numerical simulations. The large amplitude of VIV is interpreted as due to a tendency towards lockin because of the approaching of the vortex shedding frequency to a natural vibration mode of the system. The integrated numerical and experimental framework finally inspires two different design solutions for mitigating the amplitude of VIV: these strategies are tested at the wind tunnel and they are indeed shown to be effective.

Influence of Wind Speed, Wind Direction and Turbulence Model for Bridge Hanger: A Case Study

“…However, wind tunnel tests cannot be widely used in the study of a wind-induced structural response because these tests require a substantial amount of resources, where these tests are limited to a certain number of pressure taps, and some information about separation zones, recirculation, and so forth might get lost [19,20]. On the contrary, the numerical calculation method, that is, computational fluid dynamics model, can obtain the corresponding structural stress response by setting different wind speeds and wind directions based on the finite element method [21]. For example, Huang et al [22] ran a 3D CFD model to examine scale effects on turbulent flow and sediment scour.…”