This paper presents a numerical and experimental study of the hydrodynamic behavior and performance of a horizontal cylinder-type wave energy converter (WEC) with off-centered axes of rotation. The efficiency of the horizontal cylindertype WEC with off-centered axes of rotation is comparable with the asymmetric WEC. Numerical calculations based on the OpenFOAM open source computational fluid dynamics code were used to analyze the dynamic behavior of the horizontal cylinder-type WEC with off-centered axes of rotation in the wave field. The numerical wave tank is modeled with the eccentric horizontal cylinder-type WEC constrained to a single degree of freedom (pitch mode) interDyMFoam, an Open-FOAM solver that solves the Reynolds-averaged Navier-Stokes equations for two incompressible phases using the volume of fluid technique and an arbitrary mesh interface, was used for simulating the rotational motion of WEC. The effects of both the position of the center of rotation and the incident wave height were evaluated by comparisons of the results of the free decay tests and the response amplitude operators. The results obtained by numerical simulations were compared with the experimental data. Moreover, body motion was analyzed in the frequency domain considering the linear viscous damping coefficient obtained from the free decay test, and the obtained results were also compared with experimental data. Furthermore, energy losses as a result of different incident wave heights were investigated considering the nonlinear motion response. The extracted powers of the horizontal cylinder-type WECs with off-centered axes of rotation were estimated by using the optimal power take-off damping coefficients obtained from the equation of motion in the frequency domain.

INTRODUCTION

Climate change caused by increased levels of CO2 in the atmosphere as a result of the use of fossil fuels has made research on renewable energy electricity generation mainstream. Wave power is a potential renewable energy resource, and the power that can be harnessed globally from waves has been estimated to be greater than 2 TW (Thorpe, 1999). Several wave energy converters (WECs) based on various designs and concepts have been developed to obtain improved energy conversion efficiency (Drew et al., 2009). Recently, the large-scale WEC has advanced beyond the use in research applications only to commercial deployment in the real ocean environment (Pecher et al., 2014).

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