Abstract: An acoustic attenuation structure for a gas turbine engine includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Abstract: An acoustic liner includes a first face sheet, a second face sheet spaced from the first face sheet, and a plurality of sidewalls extending between the first face sheet and the second face sheet. The plurality of sidewalls defines a plurality of cells. Each cell of the plurality of cells defines a cavity between the first face sheet and the second face sheet. A bulk absorber is disposed within at least one cell of the plurality of cells. The bulk absorber further defines the cavity of the at least one cell of the plurality of cells. The first face sheet defines a plurality of apertures extending through a thickness of the first face sheet. Each aperture of the plurality of apertures is aligned with a respective cell of the plurality of cells.

Abstract: An acoustic attenuation structure includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Abstract: A noise attenuation panel for a structure within a propulsion system includes a first plurality of unit cells; and a second plurality of unit cells, the second plurality of unit cells merged within the first plurality of unit cells, the first plurality of unit cells including a first periodic structure having a first unit cell, a second unit cell, a third unit cell and a fourth unit cell, each of the first unit cell, the second unit cell, the third unit cell and the fourth unit cell including a central body interconnected via a plurality of lateral tubes extending from the central body, the first periodic structure forming a first lateral layer of unit cells.

Abstract: A noise and vibration attenuation panel for a structure within a propulsion system includes a first plurality of unit cells and a first plurality of mass elements disposed within the first plurality of unit cells. The first plurality of unit cells include a first periodic structure having a first unit cell, a second unit cell, a third unit cell, and a fourth unit cell, each of the first unit cell, the second unit cell, the third unit cell and the fourth unit cell including a central body interconnected via a plurality of lateral tubes extending from the central body, the first periodic structure forming a first lateral layer of unit cells. The noise attenuation panel can simultaneously control acoustic waves or energy (i.e., via noise attenuation flow paths) and vibration (i.e., via the mass elements).

Abstract: A noise attenuation panel for a structure within a propulsion system includes a first plurality of unit cells; and a second plurality of unit cells, the second plurality of unit cells merged within the first plurality of unit cells, the first plurality of unit cells including a first periodic structure having a first unit cell, a second unit cell, a third unit cell and a fourth unit cell, each of the first unit cell, the second unit cell, the third unit cell and the fourth unit cell including a central body interconnected via a plurality of lateral tubes extending from the central body, the first periodic structure forming a first lateral layer of unit cells.

Abstract: An acoustic attenuation structure for a gas turbine engine includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Abstract: An acoustic attenuation structure includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Abstract: An acoustic attenuation structure for a gas turbine engine includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Abstract: An acoustic liner includes a first face sheet, a second face sheet spaced from the first face sheet, and a plurality of sidewalls extending between the first face sheet and the second face sheet. The plurality of sidewalls defines a plurality of cells. Each cell of the plurality of cells defines a cavity between the first face sheet and the second face sheet. A bulk absorber is disposed within at least one cell of the plurality of cells. The bulk absorber further defines the cavity of the at least one cell of the plurality of cells. The first face sheet defines a plurality of apertures extending through a thickness of the first face sheet. Each aperture of the plurality of apertures is aligned with a respective cell of the plurality of cells.

Abstract: An acoustic liner includes a first face sheet, a second face sheet spaced from the first face sheet, and a plurality of sidewalls extending between the first face sheet and the second face sheet. The plurality of sidewalls defines a plurality of cells. Each cell of the plurality of cells defines a cavity between the first face sheet and the second face sheet. A bulk absorber is disposed within at least one cell of the plurality of cells. The bulk absorber further defines the cavity of the at least one cell of the plurality of cells. The first face sheet defines a plurality of apertures extending through a thickness of the first face sheet. Each aperture of the plurality of apertures is aligned with a respective cell of the plurality of cells.

Abstract: An acoustic liner includes a first face sheet, a second face sheet spaced from the first face sheet, and a plurality of sidewalls extending between the first face sheet and the second face sheet. The plurality of sidewalls defines a plurality of cells. Each cell of the plurality of cells defines a cavity between the first face sheet and the second face sheet. A bulk absorber is disposed within at least one cell of the plurality of cells. The bulk absorber further defines the cavity of the at least one cell of the plurality of cells. The first face sheet defines a plurality of apertures extending through a thickness of the first face sheet. Each aperture of the plurality of apertures is aligned with a respective cell of the plurality of cells.