Wavepackets driving trailing edge noise. Part I - direct simulation and experiments

Resumo

© 2024, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.The aim of present work is to investigate trailing-edge noise generation mechanisms to improve prediction tools and control strategies. We focus on a NACA 0012 airfoil at 3 degrees angle of attack with zigzag tripping elements close to the leading edge to generate a turbulent boundary layer. A compressible implicit large eddy simulation (LES), using the open-source high-order numerical framework PyFR, is performed for collecting data for our analysis. For comparison, we use data from an experimental campaign performed in parallel at the facility in TU Berlin. The comparison of velocity and sound pressure statistics shows good agreement between simulations and experiments. Further, spectral proper orthogonal decomposition (SPOD) is applied to the LES dataset to investigate dominant feature of the turbulent boundary layer and its relation to sound radiation. SPOD analysis is applied to different spanwise wavenumbers in order to understand their contribution to noise generation. Leading SPOD modes for the first spanwise wavenumbers, which dominate acoustic radiation, are shown to correspond to wavepackets. The contribution of such coherent structures in the radiated sound field is examined, clarifying their contribution to trailing-edge noise for a wide range of frequencies.