Effect of Tailing-Edge Thickness on Aerodynamic Noise for Wind Turbine Airfoil

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.

Experimental and Numerical Analysis of the Effect of a New Lightning Protection System on Lightning Protection and Aerodynamic Noise Performance of Wind Turbine Blades

“…The detached eddy simulation (DES) method is a hybrid simulation method of Reynolds average Navier-Stokes (RANS)/large eddy simulation (LES) [41].…”

“…The results showed that this method can be used to design vertical axis wind turbines with less noise and to determine the location of wind turbines with the least noise pollution. In 2019, Li et al [41] used computational fluid dynamics (CFD) and acoustic analogy to study the influence of the trailing edge thickness of a wind turbine airfoil on the aerodynamic noise of the airfoil. The results showed that the blunt trailing edge airfoil had a higher lift, but the aerodynamic noise of the trailing edge was also large.…”

Analysis of the Effect of Vortex Generator Spacing on Boundary Layer Flow Separation Control

“…A large eddy simulation (LES) is a spatial average of turbulent fluctuations, that is, large-scale vortices and small-scale vortices are separated using a filtering function [42]. More specifically, large-scale vortices are simulated directly, while small-scale vortices are closed using models.…”

Experimental and Numerical Analysis of the Effect of Vortex Generator Installation Angle on Flow Separation Control

“…In order to demonstrate mesh grid convergence, three sets of computational meshes with different densities were set up: 2,560,000 cells (coarse), 3,645,000 cells (medium), and 5,000,000 cells (fine). The three sets of computational results were obtained numerically, and the Richardson extrapolation method [41] was used to demonstrate convergence. Table 2 shows the results of the calculations and Richardson extrapolation.…”