Abstract: A method for sound attenuation in an exhaust section of an aircraft engine is provided. An exhaust is flowed into the exhaust section, via an exhaust inlet, towards an annular body in the exhaust section, the annular body having an radially outer sheet, a radially inner sheet, and an annular cavity defined between the radially outer sheet and the radially inner sheet, the annular cavity being subdivided into sub-cavities by one or more plates in the annular cavity. Acoustic pressure waves are transmitted from the exhaust flow into the sub-cavities via holes defined through the radially outer sheet to attenuate noises generated by the exhaust flow. The exhaust flow is exhausted from the exhaust section via an exhaust outlet.

Abstract: An aircraft engine, has: an engine core including a compressor and a combustor; a casing defining a bleed port downstream of an inlet of the compressor and upstream of the combustor; a bleed air system connected to the bleed port and having: a bleed air conduit communicating with the bleed port and defining a bleed passage; and a connector connecting the bleed port to the bleed air conduit and extending from a port end at the bleed port to a conduit end at the bleed air conduit, the connector having a peripheral wall extending around a connector axis transversally intersecting the casing, the peripheral wall having an inner surface facing and exposed to the bleed passage, the inner surface defining ribs extending at least partially circumferentially around the connector axis, the ribs being axially distributed relative to the connector axis between the port end and the conduit end.

Abstract: An aircraft engine, has: an engine core including a compressor and a combustor; a casing defining a bleed port downstream of an inlet of the compressor and upstream of the combustor; a bleed air system connected to the bleed port and having: a bleed air conduit communicating with the bleed port and defining a bleed passage; and a connector connecting the bleed port to the bleed air conduit and extending from a port end at the bleed port to a conduit end at the bleed air conduit, the connector having a peripheral wall extending around a connector axis transversally intersecting the casing, the peripheral wall having an inner surface facing and exposed to the bleed passage, the inner surface defining ribs extending at least partially circumferentially around the connector axis, the ribs being axially distributed relative to the connector axis between the port end and the conduit end.

Abstract: An acoustic panel is provided that includes a first skin, a second skin and a cellular core. The first skin includes a plurality of perforations. The perforations are configured to provide the first skin with a percentage of open area that changes according to a non-linear function as the first skin extends in a first direction. Spacing between at least some of the perforations vary as the first skin extends in the first direction. The cellular core is arranged between and is connected to the first skin and the second skin. The cellular core includes a plurality of chambers. Each of the chambers extends between the first skin and the second skin. Each of the chambers is fluidly coupled with a respective one or more of the perforations.

Abstract: An acoustic panel is provided that includes a first skin, a second skin and a cellular core. The first skin includes a plurality of perforations. The perforations are configured to provide the first skin with a percentage of open area that changes according to a non-linear function as the first skin extends in a first direction. Sizes of at least some of the perforations vary as the first skin extends in the first direction. The cellular core is arranged between and is connected to the first skin and the second skin. The cellular core includes a plurality of chambers. Each of the chambers extends between the first skin and the second skin. Each of the chambers is fluidly coupled with a respective one or more of the perforations.

Abstract: Sandwich-structured noise-attenuating and/or structural panels and methods of manufacturing such panels using ultrasonic welding are described. The method includes: receiving a backing member, a sheet and a cellular structure; assembling the cellular structure between the backing member and the sheet; and ultrasonically welding the backing member and the sheet together.

Abstract: A turbo-compounded engine includes a piston engine connected to drive a propulsor. An outlet of the piston engine is operable to connect products of combustion from the piston engine to pass over a turbine. The turbine is connected to drive a turbine shaft also connected to drive the propulsor. An outlet of the turbine is connected into an exhaust duct configured to exhaust the products of combustion. The exhaust duct is provided with an exhaust duct outer wall defining an exhaust chamber. A further cooling air outer wall is positioned outwardly of the exhaust duct. Flow dividers are received within an exhaust chamber inward of the exhaust duct outer wall. The exhaust duct outer wall has an inner surface and the flow dividers have an outer surface. Acoustic treatment is provided on both the inner surface of the exhaust duct outer wall and the outer surface of the flow dividers.

Abstract: A turbo-compounded engine includes a piston engine connected to drive a propulsor. An outlet of the piston engine is operable to connect products of combustion from the piston engine to pass over a turbine. The turbine is connected to drive a turbine shaft also connected to drive the propulsor. An outlet of the turbine is connected into an exhaust duct configured to exhaust the products of combustion. The exhaust duct is provided with an exhaust duct outer wall defining an exhaust chamber. A further cooling air outer wall is positioned outwardly of the exhaust duct. Flow dividers are received within an exhaust chamber inward of the exhaust duct outer wall. The exhaust duct outer wall has an inner surface and the flow dividers have an outer surface. Acoustic treatment is provided on both the inner surface of the exhaust duct outer wall and the outer surface of the flow dividers.

Abstract: An acoustic system is provided that includes a face skin, a back skin and a cellular core arranged between the face skin and the back skin. The face skin includes a first member, a second member and a plurality of ports extending through the face skin. The first member includes a plurality of first perforations. The second member includes a plurality of second perforations and is configured to move along the first member. Each of the ports includes a respective one of the first perforations and a respective one of the second perforations. The cellular core includes a plurality of chambers. Each of the chambers extends between the face skin and the back skin. Each of the chambers is fluidly coupled with a respective one or more of the ports.

Abstract: A turbo-compounded engine includes a piston engine connected to drive a propulsor. An outlet of the piston engine is operable to connect products of combustion from the piston engine to pass over a turbine. The turbine is connected to drive a turbine shaft also connected to drive the propulsor. An outlet of the turbine is connected into an exhaust duct configured to exhaust the products of combustion. The exhaust duct is provided with an exhaust duct outer wall defining an exhaust chamber. A further cooling air outer wall is positioned outwardly of the exhaust duct. Flow dividers are received within an exhaust chamber inward of the exhaust duct outer wall. The exhaust duct outer wall has an inner surface and the flow dividers have an outer surface. Acoustic treatment is provided on both the inner surface of the exhaust duct outer wall and the outer surface of the flow dividers.

Abstract: A turbo-compounded engine includes a piston engine connected to drive a propulsor. An outlet of the piston engine is operable to connect products of combustion from the piston engine to pass over a turbine. The turbine is connected to drive a turbine shaft also providing rotation to the propulsor. An outlet of the turbine is connected into an exhaust duct configured to exhaust the products of combustion. The exhaust duct is provided with an exhaust duct outer wall defining an exhaust chamber, and a further cooling air outer wall is positioned outwardly of the exhaust duct. Struts connect a cooling chamber between the cooling air outer wall and the exhaust duct outer wall into a center bullet. The center bullet has a downstream end for directing the cooling air into the exhaust chamber at a location upstream of a downstream end of the exhaust duct outer wall.

Abstract: Sandwich-structured noise-attenuating and/or structural panels and methods of manufacturing such panels using ultrasonic welding are described. The method includes: receiving a backing member, a sheet and a cellular structure; assembling the cellular structure between the backing member and the sheet; and ultrasonically welding the backing member and the sheet together.

Abstract: An acoustic system is provided that includes a face skin, a back skin and a cellular core arranged between the face skin and the back skin. The face skin includes a first member, a second member and a plurality of ports extending through the face skin. The first member includes a plurality of first perforations. The second member includes a plurality of second perforations and is configured to move along the first member. Each of the ports includes a respective one of the first perforations and a respective one of the second perforations. The cellular core includes a plurality of chambers. Each of the chambers extends between the face skin and the back skin. Each of the chambers is fluidly coupled with a respective one or more of the ports.

Abstract: An acoustic panel is provided that includes a first skin, a second skin and a cellular core. The first skin includes a plurality of perforations. The perforations are configured to provide the first skin with a percentage of open area that changes according to a non-linear function as the first skin extends in a first direction. Sizes of at least some of the perforations vary as the first skin extends in the first direction. The cellular core is arranged between and is connected to the first skin and the second skin. The cellular core includes a plurality of chambers. Each of the chambers extends between the first skin and the second skin. Each of the chambers is fluidly coupled with a respective one or more of the perforations.

Abstract: An acoustic panel is provided that includes a first skin, a second skin and a cellular core. The first skin includes a plurality of perforations. The perforations are configured to provide the first skin with a percentage of open area that changes according to a non-linear function as the first skin extends in a first direction. Spacing between at least some of the perforations vary as the first skin extends in the first direction. The cellular core is arranged between and is connected to the first skin and the second skin. The cellular core includes a plurality of chambers. Each of the chambers extends between the first skin and the second skin. Each of the chambers is fluidly coupled with a respective one or more of the perforations.

Abstract: A gas turbine engine includes a bypass duct extending about a longitudinal centerline of the gas turbine engine. The bypass duct includes at least one bypass duct wall defining at least a portion of a bypass flow path through the bypass duct. The at least one bypass duct wall includes a scoop extending into the bypass flow path. The gas turbine engine further includes a bleed conduit including an inlet connected to the bypass duct within the scoop of the at least one bypass duct wall and at least one louver mounted to the bleed conduit within the inlet. The at least one louver extends between a leading edge and a trailing edge opposite the leading edge. The leading edge is located within the bypass flow path and the trailing edge is located within the bleed conduit.

Abstract: A system is provided for a gas turbine engine. This engine system includes a flowpath wall, a takeoff conduit and a porous cover. The flowpath wall forms a peripheral boundary of an internal engine flowpath. The flowpath wall includes a takeoff port. The takeoff conduit includes an internal conduit passage fluidly coupled with the internal engine flowpath through the takeoff port. The takeoff conduit projects out from the flowpath wall. The porous cover for the internal conduit passage is disposed at the takeoff port.

Abstract: A multi-engine aircraft includes first and second gas turbine engines for providing motive power to the aircraft, each of the first and second engines comprising an air system, an air pressure line extending between and fluidly connecting the air systems of the first and second engines, and a pressure wave damper communicating with the air pressure line extending between the first and second engines.

Abstract: A gas turbine engine includes a bypass duct extending about a longitudinal centerline of the gas turbine engine. The bypass duct includes at least one bypass duct wall defining at least a portion of a bypass flow path through the bypass duct. The at least one bypass duct wall includes a scoop extending into the bypass flow path. The gas turbine engine further includes a bleed conduit including an inlet connected to the bypass duct within the scoop of the at least one bypass duct wall and at least one louver mounted to the bleed conduit within the inlet. The at least one louver extends between a leading edge and a trailing edge opposite the leading edge. The leading edge is located within the bypass flow path and the trailing edge is located within the bleed conduit.

Abstract: A method for controlling noise emitted by a hybrid-electric gas turbine engine for an aircraft during a takeoff flight condition includes applying a first total rotational force to a shaft with a turbine and an electric motor. The first total rotational force includes a first electric rotational force applied by the electric motor and a first thermal rotational force applied by the turbine. The first total rotational force has a first rotational force ratio of the first electric rotational force to the first thermal rotational force. The method further includes controlling the noise emitted by the gas turbine engine by reducing the first rotational force ratio from an initial rotational force ratio of the rotational force ratio as an altitude of the aircraft increases and maintaining the first total rotational force substantially constant while reducing the rotational force ratio.