초록 ▼

Use of bulk sound absorber-backed spaced-cell honeycomb structures as sound attenuating liners in the flow ducts of gas turbine engines involves the disadvantage that the bulk absorber may soak up water or fuel present in the honeycomb after entry thereinto from the flow duct. In order to drain away

Use of bulk sound absorber-backed spaced-cell honeycomb structures as sound attenuating liners in the flow ducts of gas turbine engines involves the disadvantage that the bulk absorber may soak up water or fuel present in the honeycomb after entry thereinto from the flow duct. In order to drain away liquid before it comes into contact with the bulk absorber, each honeycomb cell communicates with surrounding cells via apertures in the cell walls through which the liquid can drain, and a perforated sheet is provided between the honeycomb layer and the bulk absorber layer. The perforations are such that sound can enter the bulk absorber layer, but the liquid does not, each perforation being a hole having a peripheral flange which protrudes away from the bulk absorber layer into the interior of a respective cell.

대표청구항 ▼

A sound attenuating sandwich structure comprising: a first perforate sheet member having a plurality of perforations of predetermined size therein; a second perforate sheet member spaced from said first perforate sheet member and having a lesser plurality of perforations therein than the plurality o

A sound attenuating sandwich structure comprising: a first perforate sheet member having a plurality of perforations of predetermined size therein; a second perforate sheet member spaced from said first perforate sheet member and having a lesser plurality of perforations therein than the plurality of perforations of said first sheet member, each of the perforations of said second sheet member being greater in size than the perforations of said first sheet member, and each of the perforations of said second sheet member being defined by a flanged wall extending toward and terminating short of said first sheet member; a spaced cell honeycomb layer disposed between said first and second sheet members, said honeycomb layer having a plurality of walls defining cells of the same, each of said cells of said honeycomb layer being disposed about a plurality of perforations of said first sheet member and only one perforation of said second sheet member, and the walls of each cell defining with said flanged wall of each perforation of said second sheet member a moat extending about the same, and apertures in the walls of each cell for providing communication between adjacent cells, the apertures in the walls of said cells being at least partially coextensive with the moats about the perforations in said second sheet member; an impervious backing sheet member spaced from said second sheet member in a direction away from said first sheet member; and a layer of bulk sound absorber material disposed between said second sheet member and said impervious backing sheet member.