Abstract
To study the hydrodynamic characteristics of a floating horizontal-axis tidal turbine (HATT) with rotation and surging motion under the condition of the free surface, a numerical simulation method based on CFD is established. The axial load coefficient and energy utilization ratio at different blade tip-immersion depths, surge periods and surge amplitudes were analyzed. The results show that the instantaneous values of the axial load coefficient and energy utilization ratio have obvious periodic fluctuations, and the fluctuation amplitude increases with the increase of the frequency and amplitude of surging. On this basis, the hydrodynamic load is divided into the hydrodynamic load in case of rotation only, the damping force and the additional mass force. The damping and additional mass coefficients are obtained based on the least square method. The damping coefficient of axial load coefficient changes little with the increase of surge frequency and amplitude, but increases with the increase of the blade tip-immersion depth. The damping coefficient of energy utilization ratio fluctuates periodically, and the fluctuation period is equal to the surge period. The research findings can provide relevant data for studying the coupling motion of floating tidal current energy device and control design of the output electricity.