Abstract: Under the condition of actual sea state, hydrodynamic characteristic of variable-pitch vertical axis tidal turbine is related to wave characteristics and floating carrier wave motion response. This paper simulates the wave response motion of the variable-pitch vertical axis tidal turbine by combining the turbine rotation and the axial forced surge. Using ANSYS CFX software, we analyze the flow field and hydrodynamic performance of the turbine with forced surge in the uniform flow, and study the influences rule of different surge frequencies and surge amplitudes on turbine hydrodynamic performance. The research results showed that compared with the turbine which only has rotation motion in the uniform flow, the surge motion leads to the change in the interval of wake vortex. The peak envelope mean value of turbine hydrodynamic loads makes an obvious fluctuation in surging. The fluctuation frequency is equal to the turbine’s surge frequency, and the fluctuation amplitudes have a positive correlation with the frequency and amplitude of the surge. The maximum fluctuation range of hydrodynamic loads gradually increases with the increasing frequency and increasing amplitude of the surge, while the minimum gradually reduces. The results of this study can provide a reference for turbine structural strength check.

Key words: tidal current energy, variable-pitch, vertical axis turbine, surging motion, hydrodynamic characteristics