Hydrodynamic Response Analysis and Wave Energy Absorption of Wave Energy Converters in Regular Waves

Abstract

AbstractThe hydrodynamic response and the energy capture analysis of wave energy converters (WECs) with three degrees of freedom are conducted using a frequency domain approach. Considering the coupled hydrodynamic coefficients between surge and pitch, motion responses in surge, heave, and pitch are solved for the WECs. The power take-off (PTO) damping is taken as a linear function of the velocity. The power absorption and the absorption efficiency in surge, heave, and pitch are analyzed and compared. The effects of the geometry, diameter, draft, center of gravity position, and PTO damping on the hydrodynamic response, the power absorption, and the absorption efficiency of WECs are investigated. A cylinder, a halfsphere cylinder, and a cone cylinder are examined. From the total power absorption and the efficiency, the cone is the optimum geometry. For the cylinder, the power absorption in heave increases obviously with the increase of the diameter or the draft in a certain range. For the cone, the effect of diameter and draft on the power absorption in heave is relatively small. The cone has a better ability to absorb power in surge and pitch with an intermediate draft and diameter, and the power absorption peak in pitch decreases as Zg increases. The center of gravity position has no effect on the hydrodynamic response and the power absorption in heave. For a cylinder, the optimal PTO damping in heave is higher than that in pitch and surge. The optimum frequency in heave is lower than that in pitch and surge.