Simulation of transient gusts on the NREL 5 MW wind turbine using the URANS solver THETA

Länger-Möller, Annika

doi:10.5194/wes-3-461-2018

Cited by 4 publications

(6 citation statements)

References 37 publications

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“…The corresponding governing equations for conservation of mass and momentum are, respectively, as per Equations ( 11) and (12), where u i is the mean velocity component in the x i direction, p is the pressure, ρ and µ are the density and viscosity of air, respectively, ρu i u j is the Reynolds stress, and ρb i is the gravitational force component in the x i direction. The SST k-ω model, as per Equations ( 13) and ( 14), has been widely accepted for simulating flow past airfoils [9] and was applied in this study to compute the Reynolds stress term in Equation ( 12), where k is the turbulent kinetic energy, ω is the dissipation rate of k, τ ij is the shear stress, µ t is the turbulent viscosity, and (β * , σ k , γ, β, σ ω , δ, σ ω2 ) are the equation constants.…”

Section: Methodsmentioning

confidence: 99%

“…Additionally, V T has to be transformed into the base reference observation period time V T 0 , such that it is the same as in the definition of GF, as per Equation (8). Substituting V τ and V T 0 (Equations ( 6) and ( 8)) into Equation (2), and expressing the model constant K explicitly yields Equation (9). Finally, using the extreme GF in the Zhangbin area as calculated in the previous section, 1.26, K was calculated by Equation (9) as 0.4.…”

Section: Reconstruction Of Transient Gustmentioning

confidence: 99%

“…The WRF-ARW meteorological model was employed to predict the mesoscale flow behavior, followed by a large eddy simulation (LES) model, i.e., RIAM-COMPACT, to describe the near-field flow features, and, finally, a Reynolds-Averaged Navier-Stokes (RANS) model was coupled with an FEM model to determine the flow field around the blades and the resulting stress on the blades. In a recent study [9], the aerodynamic loads on a 5-MW wind turbine during an extreme gust, modelled in accordance with the IEC 61400-1 standard, were assessed via an unsteady RANS method, and the increase of blade loading was quantified and verified. The dynamic response of this 5-MW wind turbine on a floating platform in irregular seas was investigated via an aero-servo-elastic modeling approach [10].…”

Section: Introductionmentioning

confidence: 99%

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Dynamic Amplification of Gust-Induced Aerodynamic Loads Acting on a Wind Turbine during Typhoons in Taiwan

Lin¹,

Yang²,

Chau

et al. 2021

JMSE

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Typhoons, such as Soudelor, which caused the collapse of several onshore wind turbines in 2015, pose a considerable challenge to Taiwan’s wind energy industry. In this study the characteristics of the aerodynamic loads acting on a wind turbine due to wind gusts in a typhoon are studied with a view to providing a proper definition of the S-Class wind turbine proposed in International Electrotechnical Commission (IEC) 61400-1. Furthermore, based on analysis of wind data during typhoons, as obtained from the meteorological mast in the Zhangbin coastal area, an extreme wind speed and gust model corresponding to the typhoon wind conditions in Taiwan are herein proposed. Finally, the flow fields around a parked wind turbine experiencing both an unsteady gust and a steady extreme wind were simulated by a numerical approach. Numerical results show that the aerodynamic shear force and overturning moment acting on the target wind turbine in a steady wind are significantly lower than those under an unsteady gust. The gust-induced amplification factors for aerodynamic loadings are then deduced from numerical simulations of extreme wind conditions.

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Section: Methodsmentioning

confidence: 99%

Section: Reconstruction Of Transient Gustmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamic Amplification of Gust-Induced Aerodynamic Loads Acting on a Wind Turbine during Typhoons in Taiwan

Lin¹,

Yang²,

Chau

et al. 2021

JMSE

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“…The wind realisations at 90 m above the open sea level were generated using the Weibull distribution with a scale parameter of 10 and shape parameter of 2.0, resulting in 8.86 m/s mean wind speed and 4.63 m/s standard deviation. The horizontal nacelle excitation force F e (t) was then calculated using the rotor thrust data from the characteristics of 'Steady-state responses as a function of wind speed' [26], which is generally consistent with [44].…”

Section: Test Conditionsmentioning

confidence: 99%

Comparison of Floating Offshore Wind Turbine Tower Deflection Mitigation Methods Using Nonlinear Optimal-Based Reduced-Stroke Tuned Vibration Absorber

Martynowicz,

Katsaounis,

Mavrakos

2024

Energies

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Tower fatigue and strength are crucial operational concerns of floating offshore wind turbines (FOWTs) due to the escalation of the vibration phenomena observed on these structures as compared to land-based ones. FOWT towers are excited by wave and wind polyperiodic disturbances yielding continual transient states of structural vibration that are challenging for vibration mitigation systems. Thus, the paper investigates a novel implementation of nonlinear optimal-based vibration control solutions for the full-scale, tension leg platform (TLP)-based, NREL 5MW wind turbine tower-nacelle model with a 10-ton tuned vibration absorber (TVA), equipped with a magnetorheological (MR) damper, located at the nacelle. The structure is subjected to excessive wave and wind excitations, considering floating platform motions derived from model experiments in a wave tank. The MR damper operates simultaneously with an electromagnetic force actuator (forming a hybrid TVA) or independently (a semiactive TVA). The study includes both actuators’ nonlinearities and dynamics, whereby the former are embedded in the Hamilton-principle-based nonlinear control solutions. The TVA is tuned either to the NREL 5MW tower-nacelle 1st bending mode frequency (TVA-TN) or to the TLP surge frequency (TVA-TLP). The optimal control task was redeveloped concerning the TVA stroke and transient vibration minimisation, including the implementation of the protected structure’s acceleration and relative displacement terms, as well as the nonzero velocity term in the quality index. The regarded model is embedded in a MATLAB/Simulink environment. On the basis of the obtained results, the TVA-TN solution is by far superior to the TVA-TLP one. All the regarded TVA-TN solutions provide a tower deflection safety factor of ca. 2, while reference systems without any vibration reduction solutions or with a passive TVA-TLP are at risk of tower structural failure as well as the hybrid TVA-TLP system. The obtained TVA stroke reductions of 25.7%/22.0% coincide with 3.6%/10.3% maximum tower deflection reductions for the semiactive/hybrid TVA-TN case (respectively) with regard to the previously developed approaches. Moreover, these reductions are obtained due to the sole control algorithm enhancement; thus, no additional resources are necessary, while this attainment is accompanied by a reduction in the required MR damper force. The lowest obtained TVA stroke amplitude of 1.66 m is guaranteed by the newly introduced semiactive control. Its hybrid equivalent ensures 8% lower primary structure deflection amplitude and reduced nacelle acceleration levels thanks to the utilisation of the force actuator of the relatively low power (ca. 6 kW); the trade-off is an increased TVA stroke amplitude of 2.19 m, which, however, is the lowest among all the tested hybrid solutions. The analysed reference passive TVA systems, along with a modified ground-hook hybrid solution, can hardly be implemented in the nacelle (especially along the demanding side–side direction). The latter, being the well-proven hybrid solution for steady-state tower deflection minimisation, yielded unsatisfactory results. The achievements of the study may be used for an effective design of a full-scale vibration reduction system for the TLP-based floating wind turbine structure.

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“…The entire grid topology is typical for grids, constructed for the flow solver THETA, and has successfully been applied to previous wind turbine geometries. 32,35 On the blade surface, a structured grid with 123 points in spanwise direction, and 255 in chordwise direction is generated. Conversely, the grid on the nacelle surface is triangulated, with a maximum edge length of 𝛿 = 2.5 • 10 −2 m. The BL on the blade is resolved in an O-O-topology with a wall distance of 𝛿 = 1 • 10 −5 m in the first cell, ensuring y + ≤ 1 on the entire blade.…”

Section: Grid Characteristicsmentioning

confidence: 99%

Development of an interface to introduce stationary LES data to the URANS solver THETA for HAWT performance prediction

Länger-Möller¹

2019

Wind Energy

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The impact of different sheared velocity profiles on the performance prediction of a horizontal axis wind turbine in the atmospheric boundary layer is investigated. Firstly, the wall roughness in the analytical logarithmic description of the atmospheric boundary layer is varied to obtain different velocity profiles. Subsequently, it is proposed to replace the analytical logarithmic description of the atmospheric boundary layer by the time-averaged velocity data of a precursor large eddy simulation (LES) and to reconstruct the turbulence of the velocity fluctuations. The LES data are introduced as inflow condition through a LES-RANS interface in a one-way coupling approach. Three different methods to reconstruct URANS turbulence values out of the velocity fluctuations are investigated. It is shown that the reconstruction method has an impact on the development of the velocity profile, turbulent kinetic energy, and the turbulent dissipation during the transport through the URANS domain. The different inflow data, which the horizontal axis wind turbine experiences, are responsible for changes in the overall rotor thrust (up to 2.7%) and rotor torque (up to 2.4%). Conversely, the induction factors and effective angles of attack hardly change and can well be compared with a blade element momentum method. Finally, the results of both approaches to prescribe the atmospheric boundary layer are compared. The thrust and power coefficients, and wake recovery are close to each other. Simulations are carried out on an industrial 900 kW wind turbine with the incompressible URANS solver THETA. KEYWORDSatmospheric boundary layer, horizontal axis wind turbine, incompressible URANS solver, LES-RANS interface, logarithmic velocity profile, turbulence model boundary condition, turbulence reconstruction INTRODUCTIONComputational fluid dynamic (CFD) tools that are used to analyse the aerodynamic behaviour of horizontal axis wind turbines (HAWT) can be classified in three categories. In the field of HAWT, the first CFD computation with a Reynolds-averaged Navier-Stokes (RANS) solver dates back to 1998. 1 Since then, RANS computations have become the working horse in industrial context because of its comparatively low costs. The multiple fields of application in wind energy range from the analysis of wake characteristics, 2 interaction between terrain and HAWT, 3 transition behaviour, 4 and aeroelastic effects. 5,6 Large eddy simulations (LES) are nowadays used to analyse the interaction between the atmospheric boundary layer (ABL) or terrain and the HAWT wake. 7-9 During the simulation, the HAWT is modelled by an actuator line model, while the grid spacing of the LES grid reaches up to one rotor diameter. The third approach comprises all variations of detached eddy simulations (DES) that are usually used to link the scales between the LES and the RANS for specific wind turbine configurations, for example, the analysis of unsteady loads during stall in rotor-upwind configurations 10 or standstill. 5 In order to improve the performance a...

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Simulation of transient gusts on the NREL 5 MW wind turbine using the URANS solver THETA

Cited by 4 publications

References 37 publications

Dynamic Amplification of Gust-Induced Aerodynamic Loads Acting on a Wind Turbine during Typhoons in Taiwan

Dynamic Amplification of Gust-Induced Aerodynamic Loads Acting on a Wind Turbine during Typhoons in Taiwan

Comparison of Floating Offshore Wind Turbine Tower Deflection Mitigation Methods Using Nonlinear Optimal-Based Reduced-Stroke Tuned Vibration Absorber

Development of an interface to introduce stationary LES data to the URANS solver THETA for HAWT performance prediction

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