Abstract
Numerical simulations reproducing a wind tunnel experiment on two in-line wind turbines have been performed. The flow features and the array performances have been evaluated in different inflow conditions. Following the experimental setup, different inlet conditions are obtained by simulating two grids upstream of the array. The increased turbulence intensity due to the grids improves the wake recovery and the efficiency of the second turbine. However, the inlet grid induces off-design operation on the first turbine, decreasing the efficiency and increasing fatigue loads. Typical grid flow patterns are observed past the rotor of the first turbine, up to the near wake. Further downstream, the signature of the grid on the flow is quite limited. An assessment of numerical modeling aspects (subgrid scale tensor and rotor parameterization) has been performed by comparison with the experimental measurements.
Highlights
Turbines operate in clustered configurations or in wind farms
The forces are computed in the same way as in the actuator line model (ALM), but in rotating disk actuator model (RADM) they are spread on a disk, in the axial and in the azimuthal directions, as follows:
The mesh employed for the large-eddy simulations (LES) of the wind turbine experiment consists of 960 × 240 × 360 grid-points uniformly spaced in the x, y, and z directions, respectively
Summary
Turbines operate in clustered configurations or in wind farms. Complex topography or wakes from upstream rotors in wind farms induce spatial and temporal heterogeneity in the incoming flow to a wind turbine. Grid turbulence has been widely studied [28,29,30,31], and is a well-suited case to investigate how the turbine rotors modify the incoming coherent structures This configuration allows the evaluation of the impact of the grid—both on an individual wind turbine with respect to an ideal design condition with uniform flow and no turbulence, and on wake interactions as occur in clustered configurations. We present large-eddy simulations results reproducing the three experimental configurations of [18,19] The aim of this contribution is to study the evolution of the flow field and the performances of the wind turbines for different inflow conditions and to further corroborate the experimental measurements.
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