Near-wall aerodynamic response of an acoustic liner to harmonic excitation with grazing flow

• Published in: Experiments in fluids 2019-09, Vol.60 (9), p.1-18, Article 144
• Main Authors: Léon, Olivier, Méry, Fabien, Piot, Estelle, Conte, Claudia
• Format: Article
• Language: English
• Subjects: Acoustic liners; Acoustics; Aerodynamics; Engineering; Engineering Fluid Dynamics; Engineering Thermodynamics; Flow velocity; Fluid- and Aerodynamics; Grazing flow; Harmonic excitation; Heat and Mass Transfer; Orifices; Research Article; Sound pressure; Transpiration; Velocity distribution
• ISSN: 0723-4864; 1432-1114
• DOI: 10.1007/s00348-019-2791-5

The near-orifice aerodynamic response of a single degree of freedom acoustic liner to tonal and multi-tonal excitation with grazing flow was experimentally studied. A high-magnification PIV setup was designed to provide dense 2D velocity field measurements above an orifice of the liner. The resonator near-orifice velocity dynamics near and far from resonance were shown to be significantly different, with dynamic velocity scales well captured by a lumped-element model that was also satisfactorily applied to multi-tonal forcing cases. The effects of varying the forcing acoustic sound pressure level and the tangential flow velocity scale (the friction velocity) were investigated. It was observed that a “rough-wall” analogy was not suited to account for the induced mean aerodynamic effects, but that, under certain conditions, a “transpiration wall” analogy may be of interest. Graphic abstract