Numerical Investigation of Tonal Trailing-Edge Noise Radiated by Low Reynolds Number Airfoils

A high-fidelity computational analysis carefully validated against concurrently obtained experimental results is employed to examine self-noise radiation of airfoils at transitional flow regimes, with a focus on elucidating the connection between unsteady behavior laminar separation bubble (LSB) and acoustic feedback-loop (AFL) resonant interactions observed in airfoil boundary layers. The parametric study examines AFL sensitivity changes upstream conditions loading. Implicit Large-Eddy Simulations are performed for NACA-0012 selected transitional-flow regimes which measurements recorded characteristic multiple-tone spectra dual ladder-type frequency structure. switch tone-producing no-tone-producing traced LSB size position as function Reynolds number angle attack, further substantiated by linear stability analysis. indicate strong multi-tonal noise associated attributed from slowly-growing Tollmien–Schlichting fast-growing Kelvin–Helmholtz instabilities occurring thin regions when those localized near trailing-edge (TE) either side airfoil. Such process eventually nonlinearly saturated flapping vortical modes (“rollers”) that scatter into waves TE.