INFLUENCE OF ACOUSTIC IMPEDANCE ON TRAILING-EDGE NOISE

Acoustic absorption in permeable surfaces is investigated via the numerical analysis of a trailing edge of a flat plate with a finite thickness. The trailing edge is characterized by the homogeneous distribution of pores. The porous trailing edge is analyzed numerically using a dispersed flow assumption. The Reynolds number based on the chord length varies from 1.35x10(5) to 1.35x10(6) to ensure the acoustic attenuation of the porous trailing edge at high Reynolds numbers. The numerical findings focus on the noise reduction that is attributed to the coherent flow structures of the wall-bounded turbulence interacting with the trailing edge. The anisotropy-invariant map shows that the two-component axisymmetric turbulence dominates the major part of the porous surface due to the strong generation of vortical structures. The porous surface reduces the overall sound pressure level in the range of 3dB to 8dB independent from the direction of the wave propagation.