Abstract: An aircraft auxiliary power unit sound attenuation apparatus includes a perforated body having a center aperture through which exhaust fluid passes, a backing member outwardly offset from the perforated body, a plurality of connecting members coupling the perforated body to the backing member to form a locally reacting sound attenuation member having a plurality of channels spanning outwardly from the perforated body to the backing member, and a bulk absorber disposed in each of the plurality of channels where the bulk absorber is in fluid communication with the exhaust fluid, where the locally reacting sound attenuation member is in fluid communication with an auxiliary power unit of an aircraft so that the plurality of channels are oriented in a direction crossing a pressure drop direction of an exhaust fluid flow passing through the center aperture and each channel circumscribes the center aperture.

Abstract: Within examples, a method of manufacturing a double-walled titanium conduit is described. Example methods include stitch welding multiple concentric sheets to form a stitch layer, providing the stitch layer between an inner wall and an outer wall of the double-walled titanium conduit, circumferentially seam welding the inner wall and the outer wall to the stitch layer to create a welded assembly, die forming the welded assembly at temperature and pressure to form inner structures between the multiple concentric sheets according to stitch welding lines and to enable a diffusion bond process among the inner wall, the stitch layer, and the outer wall, and removing the double-walled titanium conduit from the die.

Abstract: An aircraft engine sound attenuation apparatus includes a perforated face member, a backing member, a plurality of connecting members coupling the perforated face member to the backing member to form a plurality of channels spanning from the perforated face member to the backing member, and a bulk absorber disposed in each of the plurality of channels, wherein the plurality of channels are connected to an interior portion of an aircraft engine nacelle component so that the plurality of channels are oriented in a direction substantially normal to a direction of fluid flow pressure drop passing through the aircraft engine.

Abstract: An aircraft auxiliary power unit sound attenuation apparatus includes a perforated body having a center aperture through which exhaust fluid passes, a backing member outwardly offset from the perforated body, a plurality of connecting members coupling the perforated body to the backing member to form a locally reacting sound attenuation member having a plurality of channels spanning outwardly from the perforated body to the backing member, and a bulk absorber disposed in each of the plurality of channels where the bulk absorber is in fluid communication with the exhaust fluid, where the locally reacting sound attenuation member is in fluid communication with an auxiliary power unit of an aircraft so that the plurality of channels are oriented in a direction crossing a pressure drop direction of an exhaust fluid flow passing through the center aperture and each channel circumscribes the center aperture.

Abstract: An aircraft auxiliary power unit sound attenuation apparatus includes a perforated body having a center aperture through which exhaust fluid passes, a backing member outwardly offset from the perforated body, a plurality of connecting members coupling the perforated body to the backing member to form a locally reacting sound attenuation member having a plurality of channels spanning outwardly from the perforated body to the backing member, and a bulk absorber disposed in each of the plurality of channels where the bulk absorber is in fluid communication with the exhaust fluid, where the locally reacting sound attenuation member is in fluid communication with an auxiliary power unit of an aircraft so that the plurality of channels are oriented in a direction crossing a pressure drop direction of an exhaust fluid flow passing through the center aperture and each channel circumscribes the center aperture.

Abstract: An aircraft auxiliary power unit sound attenuation apparatus includes a perforated body having a center aperture through which exhaust fluid passes, a backing member outwardly offset from the perforated body, a plurality of connecting members coupling the perforated body to the backing member to form a locally reacting sound attenuation member having a plurality of channels spanning outwardly from the perforated body to the backing member, and a bulk absorber disposed in each of the plurality of channels where the bulk absorber is in fluid communication with the exhaust fluid, where the locally reacting sound attenuation member is in fluid communication with an auxiliary power unit of an aircraft so that the plurality of channels are oriented in a direction crossing a pressure drop direction of an exhaust fluid flow passing through the center aperture and each channel circumscribes the center aperture.

Abstract: An aircraft engine sound attenuation apparatus includes a perforated face member, a backing member, a plurality of connecting members coupling the perforated face member to the backing member to form a plurality of channels spanning from the perforated face member to the backing member, and a bulk absorber disposed in each of the plurality of channels, wherein the plurality of channels are connected to an interior portion of an aircraft engine nacelle component so that the plurality of channels are oriented in a direction substantially normal to a direction of fluid flow pressure drop passing through the aircraft engine.

Abstract: Within examples, a method of manufacturing a double-walled titanium conduit is described. Example methods include stitch welding multiple concentric sheets to form a stitch layer, providing the stitch layer between an inner wall and an outer wall of the double-walled titanium conduit, circumferentially seam welding the inner wall and the outer wall to the stitch layer to create a welded assembly, die forming the welded assembly at temperature and pressure to form inner structures between the multiple concentric sheets according to stitch welding lines and to enable a diffusion bond process among the inner wall, the stitch layer, and the outer wall, and removing the double-walled titanium conduit from the die.

Abstract: Dual flow auxiliary power unit (APU) inlets and associated systems and methods are disclosed. An inlet in accordance with one embodiment of the invention includes an entrance aperture and a divider positioned in the inlet and located to separate a first portion of the inlet from a second portion of the inlet. The first portion can be configured to couple to an engine air intake of an APU, and the second portion can be configured to direct air away from the air intake. The divider can be positioned to direct air having a first total pressure level and a first distortion level to the first portion of the inlet, and direct air having a second total pressure level and second distortion level to the second portion of the inlet. The first total pressure level can be approximately the same as or higher than the second total pressure level, or the second distortion level can be approximately the same as or higher than the first distortion level, or both.

Abstract: Dual flow auxiliary power unit (APU) inlets and associated systems and methods are disclosed. An inlet in accordance with one embodiment of the invention includes an entrance aperture and a divider positioned in the inlet and located to separate a first portion of the inlet from a second portion of the inlet. The first portion can be configured to couple to an engine air intake of an APU, and the second portion can be configured to direct air away from the air intake. The divider can be positioned to direct air having a first total pressure level and a first distortion level to the first portion of the inlet, and direct air having a second total pressure level and second distortion level to the second portion of the inlet. The first total pressure level can be approximately the same as or higher than the second total pressure level, or the second distortion level can be approximately the same as or higher than the first distortion level, or both.

Abstract: Dual flow auxiliary power unit (APU) inlets and associated systems and methods are disclosed. An inlet in accordance with one embodiment of the invention includes an entrance aperture and a divider positioned in the inlet and located to separate a first portion of the inlet from a second portion of the inlet. The first portion can be configured to couple to an engine air intake of an APU, and the second portion can be configured to direct air away from the air intake. The divider can be positioned to direct air having a first total pressure level and a first distortion level to the first portion of the inlet, and direct air having a second total pressure level and second distortion level to the second portion of the inlet. The first total pressure level can be approximately the same as or higher than the second total pressure level, or the second distortion level can be approximately the same as or higher than the first distortion level, or both.