Cooperative Motion Technology of Bionic Propulsion Hydrofoils

The cooperative motion principle and trailing vortex structure of sea turtle hydrofoils are studied while turtle is adopting the hydrofoil propulsion method.A continuous aggregated vortex rope in hydrofoil trailing vortex will be caused by the cooperative motion of hydrofoils' stroke spin and azimuth spin,the aggregated vortex interference of hydrofoils' trailing vortex and the jumping phenomena of vortex rings shedding frequency can be eliminated by the cooperative motion of left and right hydrofoils.The control system of hydrofoil propulsion experimental prototype is developed for the hydrofoils cooperation motion.The subsection control method of hydrofoils' two spin cooperative motion and the angular velocity on-line adjustment method of double hydrofoils cooperative motion are proposed.And the pool experiments of experimental prototype are conducted.Results show that,under the subsection control,straight-line navigation speed of the hydrofoils' two spin cooperative motion with cooperation value 0.5 and 1 can be increased 0.45 times and 0.82 times respectively,while navigation efficiency is increased 1.01 times and 2.49 times,comparing with the two spin alternative motion.And the angular velocity on-line adjustment method not only makes the motion coincidence degree of double hydrofoils comes to 95.2%, but also boosts 43.6%longitudinal thrust for the prototype when double hydrofoils doing cooperative motion rather than non-cooperative motion.