Modelling the nacelle wake of a horizontal-axis wind turbine under different yaw conditions

Gao, Zhiteng; Li, Ye; Wang, Tongguang; Shen, Wen Zhong; Zheng, Xing; Pröbsting, Stefan; Li, Deshun; Li, Rennian

doi:10.1016/j.renene.2021.02.140

Cited by 45 publications

(8 citation statements)

References 54 publications

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“…To consider this effect, different approaches have been applied for the modeling of the nacelle. Gao et al (2021b) carried LES computations coupled with an actuator line method to investigate the wind turbine wake. To improve the numerical accuracy of the near-wake results, they included the modeling of the tower and nacelle by body forces projected into the flow field using a piecewise function.…”

Section: Nacelle Modelingmentioning

confidence: 99%

New Actuator Disk Model for the Analysis of Wind Turbines Wake Interaction with the Ground

Adjiri

Dobrev

Benzaoui

et al. 2023

JAFM

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Wake models based on Actuator Disk theory are usually applied to optimize the wind farm layouts and improve their overall efficiency and expected AEP. Despite the effectiveness of the existing models, most Actuator Disk approaches are based on the flow axisymmetric assumption, without considering the ground effect on the wake behavior. However, it has been shown that the mast’s height, or distance from the wind turbine to the ground, has an influence on the wake expansion on both hub’s side and at downstream of the wind turbine. Therefore, in this study, a hybrid CFD-BEM-Actuator Disk approach is developed to address the lack of the existing models. In the proposed model, the 3D wind rotor is modeled by a set of blade elements. Then, the local lift and drag forces acting on each blade element are calculated using BEM theory and incorporated into the momentum equation. This BEM-AD model is implemented in a User Defined Function (UDF) that is loaded into the CFD software. Thereby, ground effects are considered to be a wall boundary and defining a wind boundary layer profile at the inlet boundary, which describes the Atmospheric Boundary Layer (ABL). For the validation of this new Actuator Disk model, an enhanced experimental study is conducted at the Dynfluid Laboratory wind tunnel (ENSAM School Paris Tech). The Particle Image Velocimetry (PIV) measurements are used for the experimental wake explorations applied to a miniature two-bladed wind turbine. The wake developments are analyzed at two different hub heights ratio, h/D = 0.7 and 1.0 (where h is the hub height, and D is the wind rotor diameter). The analysis of the outcomes showed that the numerical simulations are in good correlation with the experimental measurements of the ENSAM wind tunnel. The numerical results show that for h/D=0.7, the upper half of the rotor operates within the boundary layer whereas the lower tip vortices are mainly developed in the horizontal direction with lower intensity compared to the upper tip vortices. This effect was not observed for the case h/D=1.0 where the rotor operates outside of the boundary layer; however, the wake centerline is upward deflected at about 0.3D. The main conclusion is that a distance above 7D must be observed between wind turbines to optimize the wind farm performance and over 1D hub height be required to limit the influence of the ground boundary layer effect.

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Section: Nacelle Modelingmentioning

confidence: 99%

New Actuator Disk Model for the Analysis of Wind Turbines Wake Interaction with the Ground

Adjiri

Dobrev

Benzaoui

et al. 2023

JAFM

View full text Add to dashboard Cite

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“…Researchers have also attempted to determine how the efficiency is impacted by various internal and external forces [26,27], and how the overall wind turbine performance is affected by ice, sand, and blade roughness. Other studies have examined the effect of the hub and tower in the context of the wake flow [28][29][30][31][32]. The authors determined that they needed to formulate means of streamlining the calculations of the interaction forces and momentum on the wind turbine components so as to reduce the simulation durations for all lateral studies.…”

Section: Rotormentioning

confidence: 99%

On the Investigation of the Effect of Tower and Hub Exclusion on the Numerical Results of a Horizontal Axis Wind Turbine

2022

IJM

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In order to construct a 3D rotor model, periodicity and Multiple Reference Frame (MRF) strategies were applied to address full Computational Fluid Dynamics (CFD) that incorporate the Reynolds-averaged Navier-Stokes (RANS) equations. A simulation model was run to examine the power of the wind turbines, both including and excluding the hub and tower. The purpose of this was to identify an approach that would decrease the computational time cost of wind turbine simulation. Firstly, a full-scale horizontal axis wind turbine simulation was carried out, and subsequently, comparisons were made with the results of the wind tunnel experiment utilizing the K-omega SST and Sparlat Allmaras viscosity models. The results were compared to determine the optimum model with the lowest simulation time and highest accuracy to the experimental results. Following this, the complete models' simulation was compared to the model excluding the hub and tower in order to check the disparity in the results of the two. Additionally, to ascertain the computational cost saving, the ratio of the two simulation times was established. The findings show that the two models produce results that correspond well to the experimental results, and that the power coefficient had a greater value for the complete model than the simple model. Furthermore, it was found that the power coefficient values of the full model have significantly higher levels of similarity to the experimental values. The Sparlat Allmaras and K-omega SST viscosity models returned error percentages of 0.52% and 12.6% respectively. For the partial model utilizing the same computer device, a 5.7% error rate was recorded, with a computational time saving of approximately 34%.

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“…The post-processing step used the first-generation vortex identification method (vorticity), thus identifying only one rough vortex surface profile and constricting the phenomenon of vortex shedding (tip vortex and root vortex). To obtain more representation of the wind turbine aerodynamics, Gao (Gao et al, 2021) combined the actuator line (AL) and standard Smagorinsky sub-grid models in the Large-eddy-simulation (LES) method to reproduce the downstream flow of a model-scale wind turbine located in Gansu. In the post-processing step, the second-generation (Q) vortex identification method identified the wake vortex, allowing conceptualization of the migration and break-up of the wake vortex under yaw conditions.…”

Section: Introductionmentioning

confidence: 99%

Research on complex wake interference of aligned rotors considering the precone variation of the upstream wind turbine

Zhang

Sun

et al. 2022

Front. Mar. Sci.

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To understand the interaction wake effects of aligned horizontal-axis wind turbines, a refined and low-cost wake simulation framework is developed by combining the actuator line (AL) with a local dynamic Smagorinsky (LDS) model. Firstly, the published performance of the NREL-5MW wind turbine is used to corroborate the accuracy of the AL-LDS coupling model. Secondly, the research is extended to predict the interference between two tandem rotor wakes. The influence of the precone characteristics on the overall wake and power output of the tandem wind turbines is explored by modifying the upstream wind turbine and introducing the latest third-generation Ω vortex identification method in the post-processing procedure. According to results, the tandem wind turbines have complex wake interference, with the precone angle variation always reducing the global output power, and leading to an unstable downstream turbine wake. This is detrimental to system lifespan due to high performance fluctuation and stress and as well may have ecological implications due to sediment alteration. From results, an upwind turbine with precone angle (negative) can lead to higher downstream but lower upstream turbine performance, compared with a non-tilted turbine. Despite the optimal precone angle of the upstream wind turbine is 0°, a -2.5° proves more advantageous owing to the large flexible deformation of the turbine wingtips. The findings can serve as a continuous incentive for improving wind farm numerical simulation.

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Modelling the nacelle wake of a horizontal-axis wind turbine under different yaw conditions

Cited by 45 publications

References 54 publications

New Actuator Disk Model for the Analysis of Wind Turbines Wake Interaction with the Ground

New Actuator Disk Model for the Analysis of Wind Turbines Wake Interaction with the Ground

On the Investigation of the Effect of Tower and Hub Exclusion on the Numerical Results of a Horizontal Axis Wind Turbine

Research on complex wake interference of aligned rotors considering the precone variation of the upstream wind turbine

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