Nonsinusoidal motion effect on a self-propelled heaving foil

非正弦升沉运动对扑翼自主推进的影响

¹ School of Marine Science and Technology, Northwestern Polytechnical University, Xi’an 710072, China
² Key Laboratory of Unmanned, Underwater Vehicle Technology of Ministry of Industry and Information Technology, Northwestern Polytechnical University, Xi’an 710072, China

Received: 26 July 2021

Abstract

In order to explore the mechanism of bionic propulsion and bionic robots, to make up for the limitations of traditional propulsion with a uniform incoming flow, numerical methods are used to couple fluid dynamics and flapping foil motions, and a flapping-fluid coupling self-propulsion calculation model is established in this paper. K is used as the waveform adjustment parameter to change the waveform from triangle wave to sine wave and square wave. The self-propulsion performances of non-sinusoidal heave motion under two frequency-heaving amplitude combinations are numerically simulated to study the influence of different motion waveforms on self-propulsion velocity, efficiency and flow field structure in still water. The results show that the non-sinusoidal waveform has a great influence on the self-propulsion. With the increase of K, the closer to the square wave, the more violent the speed oscillation, the faster the starting acceleration, the greater the forward displacement and the average speed, as K decreases, self-propulsion efficiency and energy utilization continue to increase. The results of this study have certain guiding significance for the design of bionic underwater vehicles.

摘要

为了研究仿生推进机理以及仿生机器人，弥补非自主推进的局限性，采用数值方法耦合求解流体动力与扑翼运动，建立扑翼-流体耦合的自主推进计算模型，K作为波形调节参数使波形由三角波变为正弦波以及方波，数值模拟了2个频率-升沉幅值组合下非正弦升沉运动的自主推进性能，研究在静水中不同运动波形对自主推进速度、自主推进效率以及流场结构的影响。结果表明非正弦波形对自主推进运动影响很大，随着K的增大即越接近方波，速度振荡越剧烈，起动加速越快，前进位移与平均速度越大; 随着K的减小，自主推进效率及能量利用率不断增大，研究结果对仿生水下航行器的设计有一定指导意义。