Influence of angle of attack on airfoil tip noise

This study investigates the aerodynamic and aeroacoustic characteristics of airfoil tip noise for a supercritical airfoil profile at $\alpha =5°$ and $\alpha =10°$ using a hybrid noise computation approach. Wall-Resolved Large Eddy Simulations (WR-LES) were performed and validated against experimental data from the University of Toronto. The simulations captured a tri-vortex system (TVS) comprising primary, secondary, and tertiary vortices. At $\alpha =10°$, upstream shifts in the primary vortex trajectory intensified interactions with the airfoil surface, resulting in amplified surface-pressure fluctuations and increased far-field noise levels. Dynamic Mode Decomposition (DMD) pinpoints dominant acoustic sources and their radiation patterns, distinguishing between duct acoustic modes below 1500 Hz and localized sources above this frequency with clear dipole radiation patterns stemming from three noise sources: the leading-edge, trailing-edge, and side-edge noise. The far-field acoustic predictions, computed using the Ffowcs Williams–Hawkings (FW-H) analogy, showed good agreement with experimental results. Both the solid and porous FW-H formulations accurately captured noise levels, with a 3 dB increase in spectral levels observed at $\alpha =10°$ due to enhanced aerodynamic loading and vortex dynamics. Noise decomposition showed a shift in dominant sources: trailing-edge noise prevailed at $\alpha =5°$, while tip noise, driven by vortex impingement and crossover, dominated at $\alpha =10°$, highlighting the complex aerodynamic-acoustic interplay.