Comparative Analysis of Hydrodynamic Performance for Flapping Hydrofoils Driven by Three Typical Transmission Mechanisms.

Abstract

This study aims to optimize bionic hydrofoil propulsion performance and establish design guidelines for efficient transmission mechanisms by comparing three mechanisms (crank-slider, cylindrical cam, and synchronous belt drive). Through 3D modeling, virtual assembly, and ADAMS simulations, dynamic responses of slider displacement and driving force/torque were obtained, revealing that the crank-slider consumes the least energy, followed by the cylindrical cam, with the synchronous belt being the most energy-intensive. Further CFD analysis demonstrated that while the crank-slider generates drag intermittently, the cylindrical cam and synchronous belt sustain continuous thrust. All mechanisms achieve effective water propulsion below their critical frequencies (0.25 Hz, 0.75 Hz, and 1.4 Hz, respectively). Propulsion efficiency peaks at 26.0% (crank-slider) and 24.7% (cylindrical cam) at 0.25 Hz but declines at higher frequencies, whereas the synchronous belt reaches 24.3% efficiency at 1 Hz with superior frequency adaptability. The synchronous belt emerges as the optimal solution for efficient flapping propulsion due to its motion continuity and frequency adaptability. This work elucidates the critical impact of transmission mechanisms on hydrofoil hydrodynamics, providing foundational insights for mechanism design and performance optimization.