scholarly journals An actuator‐line model with Lagrangian‐averaged velocity sampling and piecewise projection for wind turbine simulations

Wind Energy ◽  
2021 ◽  
Author(s):  
Shengbai Xie
2019 ◽  
Vol 1256 ◽  
pp. 012030 ◽  
Author(s):  
Andrés Guggeri ◽  
Martín Draper ◽  
Bruno López ◽  
Gabriel Usera

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 282
Author(s):  
Feifei Xue ◽  
Heping Duan ◽  
Chang Xu ◽  
Xingxing Han ◽  
Yanqing Shangguan ◽  
...  

On a wind farm, the wake has an important impact on the performance of the wind turbines. For example, the wake of an upstream wind turbine affects the blade load and output power of the downstream wind turbine. In this paper, a modified actuator line model with blade tips, root loss, and an airfoil three-dimensional delayed stall was revised. This full-scale modified actuator line model with blades, nacelles, and towers, was combined with a Large Eddy Simulation, and then applied and validated based on an analysis of wind turbine wakes in wind farms. The modified actuator line model was verified using an experimental wind turbine. Subsequently, numerical simulations were conducted on two NREL 5 MW wind turbines with different staggered spacing to study the effect of the staggered spacing on the characteristics of wind turbines. The results show that the output power of the upstream turbine stabilized at 5.9 MW, and the output power of the downstream turbine increased. When the staggered spacing is R and 1.5R, both the power and thrust of the downstream turbine are severely reduced. However, the length of the peaks was significantly longer, which resulted in a long-term unstable power output. As the staggered spacing increased, the velocity in the central near wake of the downstream turbine also increased, and the recovery speed at the threshold of the wake slowed down. The modified actuator line model described herein can be used for the numerical simulation of wakes in wind farms.


Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 776 ◽  
Author(s):  
Ruiwen Zhao ◽  
Angus C. W. Creech ◽  
Alistair G. L. Borthwick ◽  
Vengatesan Venugopal ◽  
Takafumi Nishino

Close-packed contra-rotating vertical-axis turbines have potential advantages in wind and hydrokinetic power generation. This paper describes the development of a numerical model of a vertical axis turbine with a torque-controlled system using an actuator line model (ALM). The developed model, coupled with the open-source OpenFOAM computational fluid dynamics (CFD) code, is used to examine the characteristics of turbulent flow behind a single two-bladed vertical-axis turbine (VAT). The flow field containing the turbine is simulated by solving the unsteady Reynolds-averaged Navier-Stokes (URANS) equations with a k - ω shear stress transport (SST) turbulence model. The numerical model is validated against experimental measurements from a two-bladed H-type wind turbine. Turbine loading is predicted, and the vorticity distribution is investigated in the vicinity of the turbine. Satisfactory overall agreement is obtained between numerical predictions and measured data on thrust coefficients. The model captures important three-dimensional flow features that contribute to wake recovery behind a vertical-axis turbine, which will be useful for future studies of close-packed rotors with a large number of blades.


Author(s):  
Sebastian Henao ◽  
Aldo G. Benavides ◽  
Omar D. López

The current trend in the wind power market is to develop large diameter rotors in order to maximize the power extraction from the wind. Those rotors exhibit issues related to blade deflection and structural integrity that can be mitigated implementing design variations that were present on the early wind turbine designs, such as rotors with less than three blades located behind the tower in downwind configuration. This work assesses the aerodynamic performance of a downwind two-bladed wind turbine based on CFD simulations coupled with the Actuator Line Model (ALM). This design is compared with the MEXICO project upwind three-bladed wind turbine, for which experimental data is available. The simulations showed good agreement with measurements especially upstream the rotor and for higher inlet velocities. Furthermore, the downwind configuration was successfully modeled using ALM and the performance prediction of the turbines was physically accurate since realistic variations were obtained between the evaluated wind turbines and none of their performance coefficients exceeded Betz theoretical limit.


Author(s):  
Murphy Leo O’Dea ◽  
Laila Guessous

Large-scale wind turbine installations are sited using layouts based on site topology, real estate costs and restrictions, and turbine power output. Existing optimization programs have limited capabilities to site multiple turbines and are based on simple geometric turbine wake models, which typically overestimate individual turbine output. Alternatively, complete CFD modeling of entire wind turbine fields requires enormous computational resources, which has led to the development of blade modeling techniques which are combined with CFD field computations. The most promising method, using the actuator line model, typically uses an exponential function to spread blade forces over CFD grid points. In addition, little development work has been performed to determine the optimal grid point density and force spreading radius for these methods. In this paper, we report on our ongoing efforts to develop an advanced actuator line formulation which uses an alternate geometric method for distributing blade forces to the CFD field. Domain and blade force application parameters are currently being developed to determine optimum run time conditions for the new actuator line model. The Actuator line method is implemented using the parallel CFD program, NEK5000. NEK5000 is an advanced Navier Stokes code which uses spectral methods for the spatial discretization, and has been proven to provide high-resolution results with significantly reduced compute resources. A Large Eddy Simulation turbulence model is used. In this paper, we report on our current work using large scale supercomputer resources at the Extreme Science and Engineering Discovery Environment (XSEDE) to perform computational experiments to validate our codes, and perform parametric studies to develop optimum run time parameters. Development and verification work is centered around domain size, grid spacing and clustering, and development of steady state conditions. The parametric studies are underway and are based on investigating various selection volume and force application point settings. Continuing work will compare the new actuator line method with a traditional exponential force distribution model.


Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1233
Author(s):  
Ziying Yu ◽  
Zhenhong Hu ◽  
Xing Zheng ◽  
Qingwei Ma ◽  
Hongbin Hao

The scale of a wind turbine is getting larger with the development of wind energy recently. Therefore, the effect of the wind turbine blades deformation on its performances and lifespan has become obvious. In order to solve this research rapidly, a new elastic actuator line model (EALM) is proposed in this study, which is based on turbinesFoam in OpenFOAM (Open Source Field Operation and Manipulation, a free, open source computational fluid dynamics (CFD) software package released by the OpenFOAM Foundation, which was incorporated as a company limited by guarantee in England and Wales). The model combines the actuator line model (ALM) and a beam solver, which is used in the wind turbine blade design. The aeroelastic performances of the NREL (National Renewable Energy Laboratory) 5 MW wind turbine like power, thrust, and blade tip displacement are investigated. These results are compared with some research to prove the new model. Additionally, the influence caused by blade deflections on the aerodynamic performance is discussed. It is demonstrated that the tower shadow effect becomes more obvious and causes the power and thrust to get a bit lower and unsteady. Finally, this variety is analyzed in the wake of upstream wind turbine and it is found that the influence on the performance and wake flow field of downstream wind turbine becomes more serious.


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