海龟柔性前肢仿生推进研究

Bionic Research on Turtle's Flexible Forelimb Propulsion

为探讨水翼法推进方式,进行了海龟柔性前肢仿生技术研究.基于水翼法运动解析,研究了海龟柔性水翼的弦向形变特征、反卡门涡街脱泻及斯特劳哈尔数等,推算出水翼尾涡脱泻的斯特劳哈尔数位于0.2～0.45之间,雷诺数位于3×10~2～3×10~4之间;根据海龟水翼粘弹本构特性,研制了半骼式仿生柔性水翼,并对其进行柔性形变和组织模态分析.通过水下仿生实验平台进行了半骼式柔性水翼和全骼式刚性水翼推进的直航、转艏性能对比实验,实验结果显示,虽然柔性水翼只有在较高ω_1值拍动时的推进效率才高于刚性水翼,但其速度增长率却始终高于刚性水翼;并且随着ω_1值的增长,柔性水翼对于样机速度减振方面的作用一直存在且越来越明显.实验研究结果为柔性水翼操纵与控制研究提供了技术基础.

In order to investigate the hydrofoil propulsion method,the bionic technology of the turtle＇s flexible forelimbs is studied.Based on the kinematical analysis of turtle hydrofoil,the chordwise deformation characteristics,the reverse Karman vortex street shedding,and the Strouhal number of flexible hydrofoil are studied,and then it is calculated that the Strouhal number is between 0.2 and 0.45,the Reynolds number is from 3×10~2 to 3×10~4.According to the viscoelastic constitutive property of turtle hydrofoil,the half-iliac bionic flexible hydrofoil is developed,and its flexible deformation as well as tissue mode are analyzed.By use of the underwater bionic experimental sample,the direct navigation and yawing performance contrast tests of bionic sample with the half-iliac flexible hydrofoil and whole-iliac rigid hydrofoil are conducted respectively. The experiments＇ results show that,however the propulsion efficiency of flexible hydrofoil is higher than the rigid one only moving at the high value ofω_1,the sample＇s acceleration when propelled by the flexible hydrofoil is higher than the rigid one all the time.And along with the increasing ofω_1,the function of flexible hydrofoil to reduce the velocity vibration of bionic sample,always exists and becomes more and more obvious.These experiments＇ results provide significant technical foundation for the control and manipulation study of flexible hydrofoil in the future.