可变面积仿生尾鳍设计及推力分析

Design and Thrust Analysis of Bionic Caudal Fin with Variable Area

为提高尾鳍摆动推进仿生机器鱼游动时的推力,设计了一种可变面积仿生尾鳍。建立尾鳍三维运动学模型,利用有限体积法对模型及计算区域进行离散,使用非耦合隐式求解器求解非定常不可压缩N-S方程和连续性方程;采用在尾鳍表面设置漏空区域方法,研究了相同运动学参数下,尾鳍漏空区域的形状、位置和大小等参数对推力的影响,重点对比分析固定面积与变面积推力的变化。结果表明:适时改变尾鳍面积有利于提高尾鳍摆动推进力,在给定研究条件可提高20%至25%推进力;从尾鳍表面压力和周围区域流体迹线分布情况,结合尾鳍不同切面涡结构,揭示了试验结果的内在原理。该研究成果为优化尾鳍摆动推进的仿生机器鱼设计提供了参考。

To improve the thrust force of the biomimetic fish that based on caudal fin oscillating propulsion, a biomimetic caudal fin with variable area was developed. A three dimensional kinematic model of caudal fin was established, and by taking advantage of finite volume method(FVM), the model and its corresponding computational region were dissociated. The unsteady incompressible N-S equation and continuity equation were solved by an uncoupled implicit solver. The influence of the shape, distribution and size of the caudal fin surface empty area on thrust force was investigated under the same kinematic parametersby setting an empty area on the surface of the caudal fin. Meanwhile, the force changes of fixed area and variable area were compared and analyzed. The results show that the well-timed change in caudal fin area is conductive to improve the thrust force of caudal fin swing, and the thrust force can be increased by 20% to 25% under given research conditions. Based on the pressure distribution of the caudal fin surface and the streamline of surrounding region, combined with the vortex structure on the different sections of the caudal fin, the inherent principles of the experimental results are revealed. The results provide a reference for the optimization design of the biomimetic fish that based on caudal fin oscillating propulsion.