College of Mechanical Engineering and Mechanics, Ningbo University, Ningbo, P.R. China
Smart materials have attracted growing attention for bionic locomotion, due to their excellent performance, such as enhanced maneuverability/agility, silent operation and reduced power consumption. Macro-fiber composites(MFCs)are flexible and robust piezoelectric composites made from piezo ceramic fibers and epoxy matrix, which offerstructuralflexibility,large dynamic actuation force, highperformance for a broadband application.Fish swimming mechanisms provide bionic inspirationfor underwater propulsor design. In this paper, a bionic underwater oscillatory propulsor actuated by MFCsfor carangiform locomotionis studied. Dynamic responses of the proposed propulsor with actuation of MFCs are obtained using finite element method. Oscillationdisplacement and velocity of the propulsor with different actuation voltage are presented. To understand the propulsionmechanismsof the propulsor, hydrodynamics of the propulsor are carried outby the use of Computational Fluid Dynamics (CFD).Variations of flow field with vorticity surroundingthe propulsor at different oscillationphases during one oscillationcircle are analyzed. Accordingly, the wake evolution and propulsion mechanismsare revealed. Finally, in air and underwater experiments are performed to verify the feasibility and effectiveness of the proposed propulsor. And the average thrust of the propulsor in oneoscillation circle is predicted based on the elongated-body theory. This work provides insights into the propulsion performance and mechanismsof bionicunderwater propulsor.