The design and manufacturing of optimized and cost-effective FOWT should therefore be based on the integrated dynamic modeling and analysis of FOWT. However, there are still challenges for the integrated modeling of FOWT in both frequency- and time-domain approaches.
Frequency-domain methods cannot capture the nonlinear characteristics, which are important for FOWT because the nonlinear dynamics introduced by transient events and control system actions are significant for load analysis and durability ve rification. State of the art, several sophisticated numerical codes that could carry out hydro-elastic-aero-servo simulations of FOWT in the time domain are available, such as FAST, SIMO/REFLEX/AeroDyn and HAWC2 codes. Challenges exist in the accurate sim ulations of aerodynamics, hydrodynamics, structural mechanics and mooring line dynamics. For instance, Blade Element Momentum (BEM) theory ignores the considerably different and complicated flow conditions of FOWT introduced by significant low-frequency p latform motions. In the structural modeling, blades and tower are simulated as Euler-Bernoulli beams, without accounting for the local deformation.
This research is to develop frequency-domain (simplified) and time-domain (refined) method for integrated modeling and analysis of FOWT. Refined method should, if possible, involve the nonlinear wave theory, turbulent wind simulation, elastic body modeling, and nonlinear integrated dynamic analysis; and reasonable simplification can also be made to facilitat e the design of FOWT. All the methods motioned above could be adopted to determine the load stress so as to verify sufficient durability of FOWT, such as fatigue and wear. And validation by laboratory model test or field measurement is favorable to evalua te these refined methods or simplified methods.
Description of the research plan:
Over the past few decades, offshore wind industry has experienced significant growth in many countries, such as USA