Comparison of two LES codes for wind turbine wake studies

The Science of Making Torque from Wind 2014

Sarlak, H.^1 ; Pierella, F.^2 ; Mikkelsen, R.^1 ; Sørensen, J.N.^1

Technical University of Denmark, Lyngby, Denmark^1

Norwegian University of Science and Technology, Trondheim, Norway^2

关键词: Near-wake flow structure;    Sub-grid scale models;    Technical University of Denmark;    Turbulence intensity;    Turbulence kinetic energy;    Velocity deficits;    Wake structures;    Wind turbine wakes;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/524/1/012145/pdf
DOI  :  10.1088/1742-6596/524/1/012145

来源: IOP

【 摘 要 】

For the third time a blind test comparison in Norway 2013, was conducted comparing numerical simulations for the rotor Cpand Ctand wake profiles with the experimental results. As the only large eddy simulation study among participants, results of the Technical University of Denmark (DTU) using their in-house CFD solver, EllipSys3D, proved to be more reliable among the other models for capturing the wake profiles and the turbulence intensities downstream the turbine. It was therefore remarked in the workshop to investigate other LES codes to compare their performance with EllipSys3D. The aim of this paper is to investigate on two CFD solvers, the DTU's in-house code, EllipSys3D and the open-sourse toolbox, OpenFoam, for a set of actuator line based LES computations. Two types of simulations are performed: the wake behind a signle rotor and the wake behind a cluster of three inline rotors. Results are compared in terms of velocity deficit, turbulence kinetic energy and eddy viscosity. It is seen that both codes predict similar near-wake flow structures with the exception of OpenFoam's simulations without the subgrid-scale model. The differences begin to increase with increasing the distance from the upstream rotor. From the single rotor simulations, EllipSys3D is found to predict a slower wake recovery in the case of uniform laminar flow. From the 3-rotor computations, it is seen that the difference between the codes is smaller as the disturbance created by the downstream rotors causes break down of the wake structures and more homogenuous flow structures. It is finally observed that OpenFoam computations are more sensitive to the SGS models.