Research On Dynamic Analysis For A Spar Type Offshore Floating Wind Turbine

Due to the energy crisis and environmental issues like pollution andglobal warming, the seeking for renewable and clean energy is becomingcrucial nowadays. Wind, wave, tidal, solar, biological and hydrologicalforces are considered as potential resources and a vast number ofresearches has been conducted in recent decades. Among these potentialresources to generate the desired power, it seems that the wind energy ismost hopeful to be reliable and practical considering in both technical andcommercial aspects. With the increasing number of fixed wind turbines,the stringent requirement for appropriate spaces on land is hard to fulfill.Besides, the visual and acoustic impact to the residents also restricts thefurther development for the on land wind turbines. On the other hand, whenthe water depth goes deep like above100meters, the cost of fixed windturbines increases too rapidly to be economically affordable. As aconsequence, more researchers have turned their attention to offshorefloating wind turbines recently which could be applied in deep water zonesand obtain more wind power since deep water seas provide steadier andstronger wind. Offshore floating wind turbine is a complicated hydro-aero-elastic-servo system, which confronts a lot of engineering challenges. This paper mainly uses numerical analysis method to conduct integratedanalysis for a5MW offshore floating wind turbine supported by a sparconcept platform. The performance of the floating wind turbine systemunder different sea states is analyzed including both motion behaviors andload characteristics. Besides, this paper discusses the difficulties andchallenges faced by the model test for floating wind turbines in deep waterbasin. The scale effect induced by Reynolds number is discussed and initialsolutions are proposed. The major content of this paper includes:1. An introduction for the design concepts of offshore floating windturbines is carried out. Meanwhile, the state-of-the-art methods toconduct integrated dynamic analysis for floating wind turbines areemphasized.2. Using linear potential flow theory, simulations are conducted for theOC3-Hywind Spar concept in frequency domain. Hydrodynamiccoefficients in frequency domain such as added mass, potentialdamping and1storder wave forces are obtained.3. Using integrated analysis code, simulations are conducted in timedomain to obtain performance of the NREL5MW wind turbinesupported by OC3-Hywind Spar. The performance of the floatingwind turbine system under different sea states is analyzed includingboth motion behaviors and load characteristics.4. The difficulties and challenges faced by the model test for floating wind turbines in deep water basin are discussed. The scale effectinduced by Reynolds number is discussed and initial solutions areproposed.Results and conclusions drawn from this paper may benefit the designand analysis for offshore floating wind turbines.