A preliminary study on the hydrodynamic propulsive force of a pair of inversely oscillating hydrofoils

摘要

Wave devouring propulsion system (WDPS) is a device that candirectly absorb wave energy and convert it into forward thrust by usingan oscillating hydrofoil. In this paper, a new WDPS concept thatcomprises a pair of inversely oscillating hydrofoils is preliminarilyinvestigated by a numerical method. Then the hydrodynamic propulsiveefficiency of the oscillating hydrofoils is numerically studied andcompared with that of one oscillating hydrofoil. The numerical resultssuggest that both WDPS concepts have average positive thrust whenthe Strouhal number (i.e. ratio of hydrofoils oscillating frequency tonavigation speed) is greater than 0.5, and both thrust propulsiveefficiency increases with Strouhal number. However, the inverselyoscillating hydrofoils concept shows better propulsive performancethan that of the conventional WDPS when the amplitude of pitchingangle is bigger than 24°.