Experimental and computational studies are performed on slit
resonators, i.e., one aperture with a high aspect ratio that spans
through the center of the plate.
An impedance tube experiment is conducted to investigate the
macroscopic response of slit apertures. The test specimens include
straight and tapered apertures. Subsequently, the effect of introducing
a bias flow is investigated.
The absorption performance increases when the sound pressure
level increases to a level that causes a production of shed vortices.
When a bias flow is introduced, the absorption coefficient reaches
its maximum absorption of the incident sound wave in the region
near the resonant frequency for a Mach number close to 9.71x10-3.
2D numerical simulations are performed and validated with the
experimental results. Good agreement is obtained for the majority
of the simulated cases. Vortex shedding and its effect on the absorption
coefficients is also investigated.