Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Influence of high inflow turbulence on the airfoil boundary layer and wall pressure spectrum
Submission Author:
Jose Rendón-Arredondo , Antioquia, Colombia , Colombia
Co-Authors:
Jose Rendón-Arredondo, Laura Botero-Bolivar, Alejandro Marulanda Tobón, Leandro de Santana
Presenter: Jose Rendón-Arredondo
doi://10.26678/ABCM.COBEM2021.COB2021-1928
Abstract
The main components in the noise produced by a single airfoil are the leading (LE) and trailing edge (TE) noise. The former is caused by the interaction of the incoming turbulence with the solid structure, whereas the TE noise is caused by the turbulence in the boundary layer, hence, in principle, it is not affected by the incoming flow conditions. However, previous researches have demonstrated that at high free-stream turbulence, the atmospheric turbulence can penetrate the boundary layer and change the stationary (mean velocity profile and boundary layer thickness) and non-stationary (velocity fluctuations) conditions beneath the boundary layer. This phenomenon and its relation with the noise produced by an airfoil has not been studied in depth or modeled yet. Understanding and modeling the effect of the incoming turbulence in the trailing edge noise generation is important to better predict the noise produced by wind turbines, mainly close to cities, where the turbulence intensity plays an important role in the performance of the rotor. This study aims to analyze numerically the effect of the free-stream turbulence in the trailing edge noise produced by an airfoil by analyzing the changes in the boundary layer thickness and mean velocity profile. Trailing-edge noise semi-empirical models were used to predict the far-field noise, using as input the result of low-cost numerical simulations. Simulations were conducted in fluent, Ansys in a NACA 0012 airfoil of 200 mm chord. The inlet velocity was set at 30 m/s, which correspond to a Reynolds number of 400000. Convergency analysis and the extrapolation of Richardson were conducted in order to determine the independency of the grid refinement on the results. Furthermore, numerical results were validated with experiments conducted at the Aeroacoustics wind tunnel facility of the University of Twente. The inlet turbulence intensity was varied up to 30%. The results showed a great effect in the mean velocity profile and boundary layer thickness, which is traduced in 2-3 dB in the predicted far-field noise in the entire frequency range.
Keywords
Trailing edge noise, Noise Prediction, High Inflow Turbulece, Boundary Layer, Richardson extrapolation
