Thrust-velocity Characteristics of a Variable Composite Wave Driven Bionic Undulating Propeller

Bionic undulating fin is more silent, efficient and environmental friendly than traditional underwater propulsion methods. To improve the thrust force and velocity of undulating propellers, we proposed a longitudinal and transverse composite wave propulsion method. A variable bionic undulating fin propeller with multi-degree-of-freedom is designed and developed. The mathematical model of the composite wave is established, and its wave control rule is proposed. Through computational fluid dynamics simulation, the hydrodynamic and motion performance of the undulating fin propeller under different longitudinal wave amplitudes and frequencies is compared. The simulation results show that the longitudinal and transverse composite wave can significantly improve the propulsion force and velocity of the undulating fin. The average and the peak value of thrust force can be increased by 28.5% and 200%, respectively. The experimental results of the physical prototype show that the stable velocity of the undulating fin at 2 Hz frequency and 20° longitudinal wave amplitude reaches 0.761 m/s, which is 14.7% higher than that without longitudinal wave. The research results show that the composite wave has better thrust and velocity performance than single sinusoidal transverse wave, which provides a new mechanism for high performance soft bionic fish.