Abstract
Noise has arisen as one of the main restrictions for the deployment of wind turbines in urban environments or in sensitive ecosystems like oceans for offshore and coastal applications. An LES model, adequately planned and resolved, is useful to describe the noise generation mechanisms in wind turbine airfoils. In this work, a wall-resolved LES model of the turbulent flow around a typical wind turbine airfoil is presented and described in detail. The numerical results obtained have been validated with hot wire measurements in a wind tunnel. The description of the boundary layer over the airfoil provides an insight into the main noise generation mechanism, which is known to be the scattering of the vortical disturbances in the boundary layer into acoustic waves at the airfoil trailing edge. In the present case, 2D wave instabilities are observed in both suction and pressure sides, but these perturbations are diffused into a turbulent boundary layer prior to the airfoil trailing edge, so tonal noise components are not expected in the far-field noise propagation. The results obtained can be used as input data for the prediction of noise propagation to the far-field using a hybrid aeroacoustic model.
Highlights
The growing awareness for the use of renewable energy has led to the development of ambitious projects to meet the increasing energy demands in a less aggressive way with the environment
Most of the noise generated by wind turbines is aerodynamic because the mechanical noise has been considerably reduced
In order to obtain a wall-resolved Large Eddy Simulations (LES) resolution, a dimensionless wall distance Δz+ = 10 to 40 is recommended
Summary
The growing awareness for the use of renewable energy has led to the development of ambitious projects to meet the increasing energy demands in a less aggressive way with the environment. Wind energy technology has been growing considerably over the last few years. In this area, noise is one of the main restrictions for the deployment of wind turbines in urban environments or in sensitive ecosystems like oceans for offshore and coastal applications. Aeroacoustics in wind turbine profiles is a technological field in development that is increasingly demanding advances that allow us to reduce the environmental impact generated. Most of the noise generated by wind turbines is aerodynamic because the mechanical noise has been considerably reduced. Only through an exhaustive knowledge of the fluid dynamics around wind turbine airfoils, the basic mechanisms of noise generation can be determined and relevant actions with the aim of reducing the consequent noise emissions could be performed
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