Slewing Effect of Twin Vertical Axis Turbines Supported by a Floating Platform Able to Rotate Around a Single Mooring System

In this study, we propose a new and innovative solution for harnessing offshore wind using vertical axis wind turbines (VAWT). The new type of FOWT is termed as Twin connection VAWT which uses single point mooring system consisting of two turbines capable of aligning itself against any wind direction. New-type vertical axis wind turbines are designed and developed by some of the present authors which are supported by separate floaters. The conceptual development and working mechanism of the proposed Twin connection VAWT is described in this paper based on experimental results. The yawing motion of proposed system about the moored point aligning itself to the direction of wind is confirmed in a series of dedicated experiments under only-wind condition. After aligning itself and turbines facing the direction of the wind, slow varying slewing motion phenomenon is observed during experiments. The wind forces acting on two VAWTs is examined in x-y plane and it is predicted that the forces acting perpendicular to the wind direction explains the slewing phenomenon. A physics model is conceptualized and developed to understand the yawing mechanism of the new system. A numerical simulation code is also developed to understand the yaw motion around the moored point using the steering motion equations. It is confirmed how the new system proposed can be utilized for generating clean energy.