仿生鱼鳍波动推进模式对游动性能影响的数值研究

仿生鱼鳍的波动运动有两种基本模式:振幅从前往后保持不变和振幅从前往后逐渐变化。通过比较仿生鱼鳍两种波动模式的特点,可以给利用仿生鱼鳍驱动的水下推进器选择合理的波动方式提供依据。基于计算流体动力学(computational fluid dynamics,CFD)技术建立两种波动模式的二维数学模型。比较分析了在相同的雷诺数及运动学参数(频率、波速和平均振幅)下两种波动模式形成的压力分布和平均推进力。给出了阻力系数随时间的变化规律。根据尾迹涡量场分布形式和涡量强度解释了两种波动模式之间存在差异的原因。从仿真结果可以看出:在相同的运动学参数下,振幅从前往后保持不变的鱼鳍波动模式产生更大的推进力,具有更高的游动稳定性。

Numerically Simulating Influence of Undulating Motion Mode of Biomimetic Fish Fin on Its Motion Performance

The undulating motion of a biomimetic fish fin can be classified into two modes: 1) the amplitude keeps constant;2) the amplitude changes gradually with its position.The study of the two modes can provide useful information for controlling an artificial fish fin.We build a two-dimensional mathematical model of the undulating motion modes with the computational fluid dynamics(CFD) technology.With the mathematical model,we compare the pressure contour and average generative force of the two motion modes with the same Re number and kinematical parameters(frequency,wave velocity and average amplitude) and discuss the change in drag coefficient with time.The simulation results show that the undulating motion mode with the constant amplitude of the fish fin generates a larger propulsion force and a higher propulsion stability.Finally,we explain the reasons for the difference between propulsion results of the two modes with the vortex distribution and intensity in the wake.