Abstract
The influence of wind turbine airfoil trailing edge thickness on aerodynamics and aerodynamic noise characteristics was studied using the computational fluid dynamics (CFD)/ Ffowcs Williams–Hawkings (FW–H) method in the present work. First, the airfoil of a DU97-W-300-flatback airfoil was chosen as the research object, and numerical method validation was performed. Three kinds of turbulence calculation methods (unsteady Reynolds average Navier-Stokes (URANS), detached eddy simulation (DES), and large eddy simulation (LES)) were investigated in detail, and three sets of grid scales were used to study the impact of the airfoil on the aerodynamic noise. Secondly, the airfoil trailing edge thickness was changed, and the impact of trailing edge thickness on aerodynamics and aerodynamic noise was investigated. Results show that three kinds of turbulence calculation methods yield the same sound pressure frequency, and the magnitude of the sound pressure level (SPL) corresponding to the mean frequency is almost the same. The calculation of the SPL of the peak value and the experimental results can match well with each other, but the calculated core frequency is slightly lower than the experimental frequency. The results of URANS and DES are closer to each other with a changing trend of SPL, and the consequences of the DES calculation are closer to the experimental results. From the comparison of two airfoils, the blunt trailing edge (BTE) airfoil has higher lift and drag coefficients than the original airfoil. The basic frequency of lift coefficients of the BTE airfoil is less than that of the original airfoil. It is demonstrated that the trailing vortex shedding frequency of the original airfoil is higher than that of the BTE airfoil. At a small angle of attack (AOA), the distribution of SPL for the original airfoil exhibits low frequency characteristics, while, at high AOA, the wide frequency characteristic is presented. For the BTE airfoil, the distribution of SPL exhibits low frequency characteristics for the range of the AOA. The maximum AOA of SPL is 4° and the minimum AOA of SPL is 15°, while, for the original airfoil, the maximum AOA of SPL is 19°, and the minimum AOA is 8°. For most AOAs, the SPL of the BTE airfoil is larger than that of the original airfoil.
Highlights
With the developments in wind energy, there are increasingly more large-scale wind farms being built close to the residential areas [1,2,3]
The results indicate that when using the detached eddy simulation (DES) method with the Ffowcs Williams–Hawkings (FW–H) equation, it can better obtain the acoustic signals of a complex flow field
In order to verify the accuracy of the numerical results, a comparison was made with experiment data for the DU97-W-300-flatback airfoil from the Sandia National Laboratories wind tunnel data for the DU97-W-300-flatback airfoil from the Sandia National Laboratories wind tunnel measurements [47]
Summary
With the developments in wind energy, there are increasingly more large-scale wind farms being built close to the residential areas [1,2,3]. This poses a problem as the noise generated from the wind turbines has a negative effect on the health and quality of life of the affected residents [4,5,6,7]. Wind turbine noise mainly consists of mechanical and aerodynamic noise. Mechanical noise is mainly caused by the irregular vibration of friction and the unbalanced forces between rotating parts of a machine. Aerodynamic noise has become an important factor in noise control of wind turbines [13]
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