US Patent 9592918 Acoustic liner

An acoustic liner that may be for a turbofan engine includes a first panel that may be non-permeable and a permeable panel spaced from the first panel. A non-permeable wall located between the first panel and the permeable panel faces in a first direction away from the first panel and a non-permeable wall, also between the panels, faces in a second direction away from the first panel and traversing the first direction. The liner may further include a plurality of sidewalls spaced from one-another, extending between the panels, and through the walls.