Analysis of hydrofoil rotation control method for improving the propulsion performance of wave-powered boats considering the effect of currents

Abstract

The wave-powered boat is a kind of mobile marine platform that can convert wave energy into thrust through the rotation of the hydrofoils. The rotation control method of the hydrofoil has a significant impact on the propulsion performance of wave powered-boats when considering ocean currents. In this paper, by establishing an equivalent instantaneous optimization model for the motion of the hydrofoil, the rotation angle that can obtain the maximum thrust is analyzed, and the relationship between the rotation angle, hydrofoil motion velocity as well as the current velocity is obtained. Subsequently, the propulsion performance of the hydrofoil under the active control method is compared with that under the passive control method through the fluid-multibody coupled analysis, and the motion parameters of the hydrofoil are explored, thus the feasibility of active control when considering the ocean currents is verified. It can be seen that the active control method based on the optimal rotation angle equation can significantly improve the propulsion performance of the wave-powered boat in the presence of currents. Under the passive control method, either increasing the stiffness or increasing the co-current velocity will make the rotation process of the hydrofoil fluctuate and disorderly. In contrast, the active control method can stabilize the rotation process of the hydrofoil, and the hydrofoil is always in a position where the maximum thrust can be obtained during rotation, thus making the propulsion performance better. The relevant research in this paper can provide a reference for similar research of the wave-powered boat.