In recent years, with the gradual maturity of onshore wind turbines and offshore platforms' technology, the floating offshore wind turbine (FOWT) has attracted a considerable number of scholars. Meanwhile, the stability of the floating platform is considered to be the most fundamental guarantee for a FOWT. Therefore, the heave plate is proposed as an efficient device for stability, which is mounted on the platform as passive equipment. In this paper, the performance of a spar-type FOWT consisting of NREL-5-MW wind turbine and OC3-Hywind platform system under the regular wave are solved by using the in-house turbine-platform-mooring coupled dynamic analysis program, FOWT-UALM-SJTU solver, which has coupled the unsteady actuator line model (UALM) and two phases computational fluid dynamic, naoe-FOAM-SJTU. Moreover, cases with heave plate and without heave plate are systematically compared with each other to identify the effect of the heave plate, which includes the aerodynamic performances and the hydrodynamic responses. The findings indicate that the aerodynamic power of the wind turbine is increased by about 3.0196%. Besides, the different degree-of-freedom platform motions are reduced obviously, especially the heave motion and the surge motion. Besides, it is shown that the velocity deficit in the near wake zone is enhanced with the reduction of surge motion and pitch motion of the offshore platform in the coupling simulation.
With the development of the offshore floating platform and the onshore wind turbine, the inevitable trend of the wind turbine is from land to sea (Wang et al., 2019; Liu et al., 2019). The offshore electric power generation is thought to be a promising future by FOWTs with abundant wind energy (Zhang et al., 2018). However, with the FOWT towards the deep-water areas, the motions response of the floating platform should be taken into account, which is the biggest difference from onshore wind turbines. Because of the different degree-of-freedom platform motions, the lopsided loads and unsteady motions are always taken place in FOWT (Chen and Basu, 2018). Moreover, Under the coupled hydro-aerodynamic, the motions of the floating platform not only the load of structure for FOWT is increased but also the electric generation efficiency is affected to be decreased. Therefore, it is necessary to keep the stability of the floating platform, for the simple reason that the stability is the foundation of the whole FOWT (Downie et al, 2000).