Theoretical And Experimental Research On Dynamic Response Of A Semi-Submersible Floating Wind Turbine

In recent years, issues like environmental pollution, energy crisis and sustainable development have aroused much concern among the public. However, traditional land-based wind turbines have been continually complained about the visual, acoustic and environmental impacts. Due to more turbulent breezes and lower annual mean wind velocity, it is technologically hard to achieve higher energy efficiency from onshore wind resource. Therefore, the industry is advancing into deep water and an increasing amount of effort is devoted to the study of offshore floating wind turbines.This paper is devoted to theoretical and experimental research on a semi-submersible offshore floating wind turbine(OC4-Deep Cwind semi-submersible concept). A 6DOF time-domain simulation code, Wind-SKLOE, is developed in Matlab based on potential flow theory and blade element momentum theory. Meanwhile, model test is undertaken in the Offshore Deepwater Basin at Shanghai Jiao Tong with the primary objective of grasping a further understand of OFWT dynamic character. In the end, the transient responses of the reference system after emergency shutdown is investigated with the numerical tool FAST. The main research in this paper is summarized as following:1. Present a comprehensive sketch of the offshore floating wind turbine concept, with emphasis on the challenges of industrial application and the state-of-the-art methodologies employed to carry out the coupled analysis.2. Develop a coupled aero-hydro simulation code, namely Wind-SKLOE, to predict time-domain motion response of offshore floating wind turbine. Linear potential flow theory is applied in the modeling of hydrodynamic loads and blade element momentum method is used to calculate aerodynamic force. Memory effects of free surface condition are addressed by impulse response theory. Besides, a dynamic wake model is incorporated to take the unsteadiness of wind into account. 3. This paper presents a detailed description of the model test conducted at Offshore Deepwater Basin in Shanghai Jiao Tong University. The correction methods of poor rotor aerodynamic performance due to low Reynolds number in a Froude scaled environment is fully discussed. 4. Validate the developed code by measured model test data. 5. Investigate transient effects on floating wind turbine dynamic response in emergency shutdown.