Vertical force generation of a vectorial thruster that employs a rigid flapping panel

The vertical force generation and flow features of a flapping panel that employs combined motion of horizontal oscillation, longitudinal rotation, and leading-edge-based pitching motion were investigated numerically. The sole vertical force generation is realized by combining the horizontal oscillation and longitudinal rotation, while the vertical force and forward thrust are obtained simultaneously by employing the combined motion of the horizontal oscillation, longitudinal rotation, and pitching motion about the leading edge of the panel. The effects of the phase shift (Ψ) of the longitudinal rotation and the amplitudes of the longitudinal rotation and pitching motion are investigated and discussed, respectively. Results show that the phase shift determines the instantaneous attitude of the panel and influences the directions of the instantaneous generated forces and thus plays an important role in the vertical force generation. The panel could generate stable forward thrust while maintaining the pitching motion constant and adjusting the longitudinal rotation amplitude, and in the meantime, the vertical force increases linearly with the rotation amplitude. On the other hand, the vertical force may change to the opposite direction when the longitudinal rotation is kept constant and the pitching amplitude is adjusted. The results of the current research show the potential of employing these kinds of combined motions to fish-tail-mimic propulsors of robotic fishes that pursue high maneuverability.