A computational and experimental study of slit resonators

Computational and experimental studies are carried out to offer validation of the results obtained from direct numerical simulation (DNS) of the flow and acoustic fields of slit resonators. The test cases include slits with 90° corners and slits with 45° beveled edges housed inside an acoustic impedance tube. Slit widths of 0.05, 0.10 and 0.20 in are used. Six frequencies from 0.5 to 3.0 kHz are chosen. Good agreement is found between computed and measured reflection factors. To provide a more critical test, comparisons are also made at frequencies near a natural resonance of the resonator. Again, good agreement is obtained. In addition, incident sound waves having a white noise spectrum and a prescribed pseudo-random noise spectrum are used in a subsequent series of tests. The computed broadband results are again found to agree well with experimental data. It is believed the present results provide strong support that DNS can eventually be a useful and accurate prediction tool for liner aeroacoustics. The usage of DNS as a design tool is discussed and illustrated by a simple example.