Currently, the turbulent flow has been applied to a range of onshore wind turbine modelling due to its spatial and temporal irregularities which is closer to the real wind field. Relevant research indicated that the explicit wind turbulence resulted in the fluctuations of wind turbine power generation and also the rotor structure forces (Schulz et al., 2014). Recent study by Li et al. (Li et al., 2015) found that the turbulent inflow causes considerably increasing of wake diffusion which may significantly affect the performance of the entire wind farm.&nbsp; 
Nevertheless, compared to onshore wind turbine, rare attention has been paid to the floating offshore wind turbines (FOWT). With the use of the blade element momentum (BEM) method, &nbsp;(Li et al., 2018) investigated the wind turbulence effect on a FOWT under irregular wave conditions. Their results raised the issue of unstable aerodynamics performance of FOWT under severe environmental conditions. As the blade aerodynamic prediction was based on a low-fidelity BEM method, the detailed turbulent wind field was unable to be resolved, leading to some uncertainty (Ehrich et al., 2018). 
To this end, the present study is aimed at investigating the turbulent wind effect of FOWT by using a high-fidelity computational fluid dynamics (CFD) method, which is expected to better predict and resolve the wind field to achieve more accurate investigation on the aerodynamics of the FOWT. The work is a follow up of our previously studies (Liu et al., 2017) (Liu et al., 2018) (Zhou et al., 2019). We will extend our FOWT study from previously uniform wind to a temporal and spatial variable turbulent wind field. The turbulent wind is firstly generated based on the Mann’s wind turbulence model (Mann, 1994) and the Von Karman turbulent model is used to represent the wind turbulence. The Mann’s turbulence model is then implemented into our CFD code as the initial conditions. The self-generated wind field data is verified against the theoretical/analytical results. The NREL-5MW semi-submersible FOWT is numerically modelled under different turbulent wind and regular wave conditions. The wind filed around the blade, the rotor performance and the power generation of the wind turbine, and the dynamic responses of the floating system, will be fully analysed.&nbsp; 
References 
1.Ehrich, S., Schwarz, C.M., Rahimi, H., Stoevesandt, B., Peinke, J., 2018. Comparison of the Blade Element Momentum Theory with Computational Fluid Dynamics for Wind Turbine Simulations in Turbulent Inflow. Applied Sciences 8, 2513. 
2.Li, L., Liu, Y., Yuan, Z., Gao, Y., 2018. Wind field effect on the power generation and aerodynamic performance of offshore floating wind turbines. Energy 157, 379-390. 
3.Li, Y., Castro, A., Sinokrot, T., Prescott, W., Carrica, P., 2015. Coupled multi-body dynamics and CFD for wind turbine simulation including explicit wind turbulence. Renewable Energy 76, 338-361. 
4.Liu, Y., Xiao, Q., Incecik, A., Peyrard, C., 2018. Aeroelastic analysis of a floating offshore wind turbine in platform-induced surge motion using a fully coupled CFD-MBD method. Wind Energy. 
5.Liu, Y., Xiao, Q., Incecik, A., Peyrard, C., Wan, D., 2017. Establishing a fully coupled CFD analysis tool for floating offshore wind turbines. Renewable Energy 112, 280-301. 
6.Mann, J., 1994. The spatial structure of neutral atmospheric surface-layer turbulence. Journal of fluid mechanics 273, 141-168. 
7.Schulz, C., Klein, L., Weihing, P., Lutz, T., Krämer, E., 2014. CFD studies on wind turbines in complex terrain under atmospheric inflow conditions, Journal of Physics: Conference Series. IOP Publishing, p. 012134. 
8.Zhou, Y., Xiao, Q., Liu, Y., Incecik, A., Peyrard, C., Li, S., Pan, G., 2019. Numerical modelling of dynamic responses of a floating offshore wind turbine subject to focused waves. Energies 12, 3482.

A CFD Study for Floating Offshore Wind Turbine Aerodynamics in Turbulent Wind Field

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/IOWTC2021/volume/84768

ASME 2021 International Offshore Wind Technical Conference (IOWTC2021)

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