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The Anti-pitching Generating WEC (AG-WEC) combines the floating articulated platform with the wave energy device. The wave energy device is installed between the hinged platform modules to provide damping to reduce the relative pitch while generating electricity at the same time. A semi-analytical solution of the dynamic characteristics of the AG-WEC is developed by the frequency- and time-domain analysis of the device based on the potential flow theory. Based on Eigenfunction Expansion Matching's potential flow theory, the semi-analytical expressions of wave loads and radiation hydrodynamic coefficients of AG-WEC are derived. By establishing a two-degree-of-freedom vibration system, the analytical solution of frequency-domain dynamic characteristics of the AG-WEC is obtained. Based on the analytical solution of Optimal PTO Damping Coefficient, the analytical optimization of the PTO system is realized, and the mechanism of high-efficiency energy capture of the device is revealed. The time-domain dynamic characteristics of AG-WEC under regular and irregular waves are analyzed by introducing the non-linear Power Take-Off (PTO) system and irregular wave theory with combining the Impose Response Function method. [ABSTRACT FROM AUTHOR]

In this work the hydrodynamic performance of a novel wave energy converter configuration was analytically and numerically studied by combining a moonpool and a wave energy buoy, called the moonpool platform–wave energy buoy (MP–WEB). A potential flow, semi-analytical approach was adopted to assess the total (incident, diffraction, radiation) wave forces acting on the device, and the wave capture and energy efficiency performance of this configuration was assessed, both in the time and frequency domain. The performance of the two configurations, single float and double float, were analyzed and compared in terms of diffraction force, added mass radiation force, motion, and power in the frequency domain. Using an impulse response function-based (IRF) method, the frequency domain results were converted in the time domain. The same parameters in the time domain were derived and the main results were confirmed. Wave energy conversion efficiency was significantly increased due to the resonance phenomenon inside the moonpool. [ABSTRACT FROM AUTHOR]

The concept of installing two wind turbines on a floating platform, known as a floating twin-rotor wind turbine system, has recently garnered significant interest. This configuration can harness greater wind energy resources, reduce installation and mooring costs by sharing mooring lines, and minimize losses due to wake effects between turbines through yaw control. However, previous research has not sufficiently addressed the dynamic performance analysis of such systems. This study focuses on a high-capacity floating twin-rotor wind turbine system and develops an aero-hydrodynamic coupled analysis method based on the free vortex wake method and potential flow theory, specifically tailored for the twin-rotor configuration. This method facilitates real-time iterative calculations of wind and wave loads acting on the system and suggests optimization strategies for its design. Our findings indicate that the design of high-capacity floating twin-rotor systems can significantly reduce costs. Furthermore, the twin-rotor floating system design enhances wake recovery and achieves optimal comprehensive performance when the rotor spacing ratio (S/D) is 1.2 for the IEA 15 MW turbine. The coupled interactions induce periodic variations in aerodynamic performance, with the amplitude of these variations increasing with turbulence intensity. This research lays a theoretical foundation for advancing the design, platform optimization, and coupled computational analyses of large-capacity, large-scale floating twin-rotor wind turbine systems. • Floating twin-rotor wind turbine system. • Simulation method combine free vortex wake and potential flow theory. • Wake analysis of twin-rotor under turbulence effect. • System aero-hydro coupled motion analysis under turbulence effect. • The rotor spacing ratio in this system is recommended to be 1.2 under consideration of wake recovery and cost. [ABSTRACT FROM AUTHOR]

Anti-pitching Generating Wave Energy Converter (AGWEC) uses the relative pitch motion between floating bodies to push the hydraulic energy storage PTO movement, which reduces the relative pitch between floating bodies while generating power. In this paper, based on the CFD method and the potential flow theory with viscosity modification, the motion characteristics of AGWEC in waves are studied. The viscous dissipation term is introduced into the boundary condition of potential flow, and the viscous modified potential flow theory method is established. The Eigenfunction Expansion Matching (EEM) method and Impulse Response Function (IRF) method are used to analyze the motion response of the device in frequency domain and time domain respectively. At the same time, compared with the results of CFD method based on Star-CCM+, the universality of the two methods is proved, and the motion characteristics of the AGWEC based on (non)linear PTO system and the variation law with the relevant parameters are obtained under different floating body axial spacing and wave frequency. • The viscous dissipation term is introduced and the viscosity disspation term of Anti-pitching Generating WEC is obtained. • Combined with CFD method, the new method is verified, and the viscosity dissipation correction coefficient is obtained. • The motion characteristics of AGWEC based on (non)linear PTO system in real fluid are studied. [ABSTRACT FROM AUTHOR]