A method of reducing noise from a high-speed, including supersonic, jet, the method includes providing the high-speed or supersonic jet in a longitudinal flow direction; and inducing a rotation of a swirl layer of the high-speed or supersonic jet around a longitudinal direction of the jet and on the jet boundary so as to promote mixing of the high-speed or supersonic jet with surrounding air.

An aircraft control system includes: a first engine attached to an airframe of an aircraft; a second engine attached to the airframe; a first power generator connected to an engine shaft of the first engine; a second power generator connected to an engine shaft of the second engine; an electric motor driven with electric power supplied from one or both of the first power generator and the second power generator; a rotor driven with a driving force output from the electric motor; and a controller configured to estimate whether noise excess conditions have been satisfied on the basis of information for estimating noise and to change one or both of a rotation speed and a magnitude of a torque such that noise is lower than that before the noise excess conditions have been satisfied when it is estimated that the noise excess conditions have been satisfied.

Disclosed are laminates comprising a carbon fiber reinforced polymer sheet and a layer of polysilazane and methods for producing such laminates.

An active noise cancellation system (1) for cancelling environment noise perceived by a driver or passenger seated in a seat (3) mounted in a cabin of a vehicle, in combination with said seat, the seat comprising a seat cushion (19), a seat back (21) coupled to the seat cushion at a bottom end and extending upwards to a seat shoulder (23), and a headrest (22) coupled to the seat back, extending upwardly from the seat shoulder, the active noise cancellation system comprising an active noise cancellation circuit (ANC) (30), a plurality of microphones (10) mounted in the headrest and connected electrically to the ANC, and a plurality of speakers (16) mounted in the seat and connected electrically to the ANC circuit. The plurality of microphones comprises at least one first microphone mounted on a right side of the headrest and at least one second microphone mounted on a left side of the headrest, and the plurality of speakers comprises at least one first speaker mounted in the seat shoulder on a left side and at least one second speaker mounted in the seat shoulder on a right side, the right speaker configured to generate a noise cancellation sound from a noise signal picked up by the right microphone processed by the ANC circuit and the left speaker configured to generate a noise cancellation sound from a noise signal picked up by the left microphone processed by the ANC circuit.

An apparatus is provided for an aircraft propulsion system. This apparatus includes an acoustic panel and a mount. The acoustic panel includes a perforated face skin, a back skin, a perforated intermediate layer, a first cellular core and a second cellular core. The first cellular core includes a first section and a second section. The first section is between and is connected to the perforated face skin and the perforated intermediate layer. The second section is between and is connected to the perforated face skin and the back skin. The second cellular core is between and is connected to the perforated intermediate layer and the back skin. The mount is attached to the back skin along the second section.

A structure is provided that includes a perforated first skin, a second skin and a core. The core includes a first sidewall, a second sidewall, a first baffle and a second baffle. The core forms a plurality of cavities vertically between the perforated first skin and the second skin. The first baffle is connected to the perforated first skin at a first baffle first end. The first baffle is connected to the second skin at a first baffle second end by a first moveable joint. The second baffle is connected to the perforated first skin at a second baffle first end. The second baffle is connected to the second skin at a second baffle second end. A first of the cavities extends laterally between the first sidewall and the second sidewall. The first cavity extends longitudinally between the first baffle and the second baffle.

An engine exhaust nozzle for a jet engine offers a controllable variable mixing of engine exhaust and the surrounding airflow. The engine exhaust nozzle includes a nozzle, slots at the downstream end of the nozzle, curved vanes extending radially inward from the inner surface of the nozzle and adjacent to the slots, and a cover connected to the outside of the nozzle and movable with respect to the nozzle so as to open and close the slots. When the slots are opened, near-field mixing is enhanced between the jet exhaust and the surrounding air, thus reducing mixing further downstream and the noise associated therewith, thus reducing the overall noise transmitted to the ground. When the slots are closed, the nozzle propulsive efficiency improves at the expense of increased noise.

An engine exhaust nozzle for a jet engine offers a controllable variable mixing of engine exhaust and the surrounding airflow. The engine exhaust nozzle includes a nozzle, slots at the downstream end of the nozzle, curved vanes extending radially inward from the inner surface of the nozzle and adjacent to the slots, and a cover connected to the outside of the nozzle and movable with respect to the nozzle so as to open and close the slots. When the slots are opened, near-field mixing is enhanced between the jet exhaust and the surrounding air, thus reducing mixing further downstream and the noise associated therewith, thus reducing the overall noise transmitted to the ground. When the slots are closed, the nozzle propulsive efficiency improves at the expense of increased noise.

A structure for the nacelle of an aircraft propulsion unit includes a first skin and stiffeners arranged to hold acoustic treatment modules against the first skin. Each acoustic treatment module includes a honeycomb core and a second skin, such that the honeycomb core is sandwiched between the first skin and the second skin. Such a structure allows the structural reinforcement function provided by the stiffeners to be separated from the acoustic treatment function performed by the acoustic treatment modules which are simply bearing on the first skin.

An acoustic absorption structure comprising a plurality of resonators. Each resonator comprises a first chamber which has a first mouthpiece delimited by an edge pressed against an inner surface of a porous zone of a skin so that the first chamber and the skin delimit a first cavity, a second chamber, in which is positioned the first chamber, which delimits, with the first chamber, a second cavity, at least one acoustic orifice passing through the first chamber, at least one drainage orifice passing through the first chamber and at least one drainage hole passing the second chamber, each drainage orifice and each drainage hole being configured to limit an accumulation of fluid in the resonator. Also, an aircraft propulsive assembly or an aircraft comprising the acoustic absorption structure are provided.