Mitigation of hydrofoil torsional flow induced vibrations by resonant piezoelectric shunt

• Published in: Ocean engineering 2024-12, Vol.313, p.119598, Article 119598
• Main Authors: Watine, Yann, Lossouarn, Boris, Gabillet, Céline, Astolfi, Jacques-André, Deü, Jean-François
• Format: Article
• Language: English
• Subjects: Engineering Sciences; Flow induced vibrations; Mechanics; Resonant piezoelectric shunt; Vibration mitigation; Vortex shedding
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2024.119598

Hydrofoils sustain severe flow induced vibrations when a hydrodynamic excitation source couples with a torsional mode of the structure. This phenomenon may induce acoustic radiations, structural fatigue and a modification of the near-wake vortex dynamics. This paper describes a numerical and experimental investigation of the impact of a resonant piezoelectric shunt on the torsional flow induced vibrations and near-wake hydrodynamic properties of a truncated hydrofoil. A Macro Fiber Composite (MFC) piezoelectric transducer was integrated in a NACA 66-306 profile and connected to a resonant shunt circuit in order to mitigate the torsional vibrations of the hydrofoil. For the shunt circuit two types of inductors were tested: a ferrite core copper coil which can sustain high voltage levels and a synthetic inductor which facilitates the tuning of the inductance value. A finite element model was set-up in order to predict the electro-mechanical properties of the system consisting of the natural frequencies and the coupling factors and optimize the shunt parameters. The computed numerical results were in high agreement with experimental data which demonstrates that the model is a valuable tool for the design of future more complex prototypes. Experimental tests were realized at zero degrees of incidence in the hydrodynamic tunnel of the French Naval Academy Research Institute at zero flow velocity in air and in water and for water flow velocities ranging from 3.0 to 5.5 m s-1 corresponding to chord-based Reynolds numbers between 2.55×105 and 4.68×105. The mechanical response of the hydrofoil was investigated using laser vibrometry and the near-wake flow was characterized by Time-Resolved Particle Image Velocimetry (TR-PIV). A significant reduction of the torsional vibrations was observed for both in air and in water configurations. A lock-in phenomenon with the first torsional mode was observed at a Reynolds number equal to 3.74×105 leading to high magnitude vibrations. For this particular regime, the resonant shunt induced a significant reduction of the vibration magnitude leading to a decrease of the velocity deficit in the wake and thus a reduction of the drag force. The results presented through this study demonstrate the high capability of resonant piezoelectric shunts to reduce torsional flow induced vibrations and pave the way for efficient vibration mitigation devices for marine and naval applications. •Passive resonant piezoelectric shunts induce a signi