Experimental impedance assessment of innovative liner under shear grazing flow

Abstract

Nomenclature φ Liner perforated sheet hole diameter, (mm) δ Liner perforated sheet thickness, (mm) POA Percent Open Area L s Thickness of the liner sample ρ 0 Density of the mean flow, (kg/m 3 ) M b Bulk flow Mach number U b Bulk flow velocity h B2A test section height ω = 2πf Angular frequency, (rad/s) Z = R + iX Acoustic impedance β Acoustic reflection coefficient (x, y, z) Axial, transversal and vertical coordinates, (mm) (U, W ) Axial and vertical mean velocity, (m/s) (u, w) Axial and vertical acoustic velocity, (m/s) c 0 Sound celerity, (m/s)