Simulation of transient gusts on the NREL5 MW wind turbine using CFD

Länger-Möller, Annika

doi:10.5194/wes-2017-47

Cited by 3 publications

(2 citation statements)

References 16 publications

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“…The simulation presented in Figure 16 was developed based on the procedures introduced by Länger‐Möller 49 who utilized a resolved gust approach for gust modeling in CFD simulation, in which time is discretized as

t_{k} = k normalΔ t

on the k th time step with

Δt = 1 / 2048 normals

corresponding to around

1^{°}

of turbine rotation, which is sufficiently small to resolve major turbulence quantities 50,51 . The PI‐controlled three‐phase PMSG system model was integrated with the CFD simulations as a control circuit module using user‐defined functions written in C.…”

Section: Gust Harvesting Ability Evaluation At Different Tracking Fre...mentioning

confidence: 99%

Optimal gust wind energy capture using critical tracking frequency for wind turbines

Chan

2022

Wind Energy

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Gusty wind in urban areas contains significant energy potential that can be harnessed, but the existing wind turbine rotor speed control systems based on continuous wind speed tracking have a noticeable response delay as compared to the duration of the common short gusts, inducing a significant deficit in harnessed excess energy content (EEC) from gusty wind. This work scrutinizes the energy content distribution among the gusty wind components and their differential impacts on the control response to identify factors to improve response timeliness. Cross-correlation spectrum analysis between the wind turbine response and the local wind spectrum was used to identify the critical tracking frequency that can significantly reduce the average response delay of wind turbines in gusty wind conditions while maximizing the gust energy harvesting ability was developed and validated by various timedomain simulation results. Combining the critical tracking frequency with the theoretical estimation of the EEC of a wind turbine, the expected EEC harnessing ability of a wind turbine can be estimated before installation. For the sample Savonius wind turbine in this work, the response delay of the wind turbine was shortened by 65%, leading to 25% more harnessed EEC from gusty wind.

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t_{k} = k normalΔ t

on the k th time step with

Δt = 1 / 2048 normals

corresponding to around

1^{°}

Section: Gust Harvesting Ability Evaluation At Different Tracking Fre...mentioning

confidence: 99%

Optimal gust wind energy capture using critical tracking frequency for wind turbines

Chan

2022

Wind Energy

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“…The remaining part of the disk is filled with tetrahedrons. The entire grid topology is typical for grids, constructed for the flow solver THETA, and has successfully been applied to previous wind turbine geometries . On the blade surface, a structured grid with 123 points in spanwise direction, and 255 in chordwise direction is generated.…”

Section: Test Casementioning

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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Simulative Investigation of the Risk of Smearing Damage for a WT Gearbox Roller Bearing during Rotor-Induced Excitations

Euler

Jacobs

Röder

et al. 2022

Wind

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Wind turbine drivetrains can be subjected to highly dynamic loading conditions caused by grid faults, power converter faults and dynamic wind excitations. These loading conditions can cause additional wear and possibly damage their components. Some of the most critical components in the mechanical drivetrain are its bearings. High-speed shaft bearings are especially prone to failure. Smearing is one possible damage pattern for these bearings. Previous studies observed a highly increased smearing risk caused by generator-induced torque excitations. In contrast, this study focuses on rotor-induced torque excitations and investigates the resulting smearing risk. The goal is to ascertain the general damage potential stemming from rotor-induced excitations for high-speed shaft bearings regarding smearing. To this end, a detailed bearing model was integrated into a validated multibody simulation of a research nacelle which was operated on a test bench. A smearing criterion was used to evaluate the smearing risk. Multiple sinusoidal rotor-induced torque excitations were investigated. The resulting smearing risk is highly dependent on the excitation amplitude and frequency, with higher amplitudes resulting in a greater smearing risk. Regarding frequency, only excitations with frequencies close to the system’s first torsional eigenfrequency result in a significantly increased smearing risk. In general, the determined amplitudes and frequencies of rotor-induced torque excitations, necessary to cause a significant increase in smearing risk, are unlikely to occur in the field and therefore are of lesser importance to the high-speed shaft bearings than generator-induced torque excitations.

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Simulation of transient gusts on the NREL5 MW wind turbine using CFD

Cited by 3 publications

References 16 publications

Optimal gust wind energy capture using critical tracking frequency for wind turbines

Optimal gust wind energy capture using critical tracking frequency for wind turbines

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

Simulative Investigation of the Risk of Smearing Damage for a WT Gearbox Roller Bearing during Rotor-Induced Excitations

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