Noise suppression panel

Claim 1

A double layer noise suppression honeycomb sandwich panel having structural strength for use in severe environments in and around high velocity fluid flow paths associated with aircraft gas turbine engines and providing a predetermined flow through resistance to satisfy acoustical requirements comprising: (a) first and second non-metallic honeycomb cores, each having a multiplicity of endwise directed cells formed with walls of thin sheet material disposed transversely to the panel, said walls terminating in a pair of cell edges, the cell edges on one side of each said honeycomb core facing the cell edges on one side of the other honeycomb core; (b) a first thin sheet of metallic microporous material positioned between the first and second honeycomb cores and adhesively bonded to the endwise facing cell edges of said honeycomb cores; (c) a perforated facing of thin sheet material having two surfaces, one of said surfaces being adhesively bonded to the endwise cell edge of said first honeycomb core opposite said first thin sheet of microporous material; (d) a second thin sheet of microporous material bonded to the other surface of said perforated facing of thin sheet material whereby air is permitted to enter the noise suppression panel and a relatively smooth outer surface is presented to a high velocity fluid flow; and (e) an impervious facing of thin sheet material adhesively bonded to the endwise cell edge of said second honeycomb core opposite said first sheet of microporous sheet material.