仿生机器鱼转向机动的水动力性能数值研究

将仿生机器鱼的C-型转向机动划分为弯曲阶段、保持阶段和伸展阶段，首先基于计算流体力学（CFD）方法建立了鱼体与流体相互作用的耦合求解方法，其次通过二次开发FLUENT实现机器鱼在C-型转向机动过程中鱼体的大变形运动，最后数值计算了机器鱼在C-型转向机动过程中的运动性能、水动力性能和流场涡结构。计算结果表明：仿生机器鱼在弯曲阶段和保持阶段进行快速的转向；在伸展阶段，机器鱼的艏向角速度和侧向速度快速的减小至零值，而前进速度则快速的增加，在伸展阶段结束时获得一个较大的前进速度；在滑行阶段，仿生机器鱼以获得的纵向速度向前滑行，并且纵向速度缓慢的减小。机器鱼的C-型转向机动能够实现小范围内的大角度转向；在弯曲阶段和伸展阶段鱼体的快速弯曲和伸展运动各产生一个涡环，每个涡环产生一个射流，射流产生作用于机器鱼上的水动力和力矩。

Numerical study on the hydrodynamic performance of the turn maneuver of a bionic robotic fish

The C-turn maneuver of bionic fish was divided into bending stage, maintaining stage and stretching stage. At first, the numerical model of fish interaction with fluid was built based on the computational fluid dynamic (CFD) technique. Then, the large deformation of the fish during the C-turn maneuver was built based on the secondary development of FLUENT. Finally, the swimming performance, hydrodynamic performance and wake structure were calculated. The results show that the bionic fish turns rapidly in the bending stage and maintaining stage. In the stretching stage, the yawing angular velocity and lateral velocity of the bionic fish tend to zero rapidly, while the longitudinal velocity increases rapidly and gains a greater forward speed at the end of the stretching stage. The C-turn maneuver of the bionic fish can realize large-angle steering in a small space. In the bending stage and stretching stage, the large deformation movement of the fish body can generate a vortex ring, and each vortex ring generates a jet flow, which generates the hydrodynamic force and moment acting on the bionic fish.