Experimental study of the effect of the cell size honeycomb core on the impedance of single-layer SAS

The study of the acoustic characteristics of sound-absorbing structures (SAS) seems to be an urgent task aimed at solving the problem of noise both in the cabin of aircraft and aircraft engine noise. Results of experimental study of the effect of the size of the cell edges of a fiberglass honeycomb core and the degree of perforation on the acoustic characteristics of single-layer sound-absorbing structures are presented. Tests of samples of sound-absorbing structures were performed on an interferometer type installation with a normal incidence of sound waves. The dependence of the acoustic characteristics of SAS on the size of the edge of the honeycomb filler is shown, in connection with the overlap of the holes of the perforated sheet of SAS with the edges of the honeycomb block. The dependence of the resonant frequency and the efficiency of the structure on the diameter of the holes of the perforated sheet are shown.