Patent ID: 8596413

Claim:
A rotating machine, comprising: a casing defining a cavity and having an impeller arranged for rotation within the cavity, the cavity being fluidly coupled to an inlet conduit and a diffuser channel; a first acoustic liner mounted to a metal diffuser wall defined in the diffuser channel to attenuate noise, the first acoustic liner being annular and having a first plurality of cells tightly-coupled together to form a first cell matrix; a second acoustic liner mounted to the metal diffuser wall opposite the first acoustic liner and adapted to attenuate noise, the second acoustic liner being annular and having a second plurality of cells tightly-coupled together to form a second cell matrix, and the first and second acoustic liners being at least partially non-metallic; and a backing member disposed between the first and second acoustic liners and the respective metal diffuser walls, wherein each cell of the first cell matrix and the second cell matrix is a single bore extending axially from the diffuser channel to the backing member, each cell of the first cell matrix and the second cell matrix defines a flowpath having a uniform cross-section from the diffuser channel to the backing member, and each cell of the first cell matrix and the second cell matrix has six or more sidewalls.