Effects of covers on dynamic response of a barge-type wind turbine with four moonpools

A floating barge-type platform equipped with moonpools and a 5 MW wind turbine is investigated using Finite Volume Method (FVM) and Volume of Fluid Method (VOF), based on fully nonlinear viscous flow theory. The computational domain, comprising both air and water, is modelled using Reynolds-Averaged Navier-Stokes (RANS) equations and continuity equations, employing the Shear Stress Transport (SST) turbulence model. Wind turbine is given a constant rotational speed, and a sliding grid is applied in the fan area to realize the rotation of the wind turbine. The overlapping grid is used in the area containing the fan, tower and the floating barge to achieve the overall motion response of the floating system. In this study, a method of reducing the tilt angle of the entire floating wind turbine system is proposed through involving covers over the free surface inside the moonpools. The results indicate that adding cover can ease the deviation of the floating system noticeably. But if adding cover, the damping effects of moonpools are suppressed, and the heave and pitch amplitude will both increase.