A gas turbine engine includes combustion apparatus defining a volume, a compressor, a cooling air supply feed from the compressor, and a Helmholtz resonator. The Helmholtz resonator has a neck and a chamber having an attenuation volume and which is in fluid communication with the attenuation volume, the cooling air supply feed is connected to the Helmholtz resonator and includes a valve arrangement. In a first engine operating condition, the valve arrangement is closed and the Helmholtz resonator attenuates acoustic frequencies in a first range and, in a second engine operating condition, the valve arrangement is open whereby cooling air purges the attenuation volume and the Helmholtz resonator attenuates acoustic frequencies in a second range.

A fairing for a power generation machine, the fairing comprising: a first layer comprising a metallic material; a second layer comprising a composite; and a third layer positioned between the first layer and the second layer, the third layer being configured to attenuate acoustic waves over a predetermined frequency range.

A fan, and a silencer that silences a sound generated by the fan are provided, in which the silencer has a resonance characteristic, the silencer is disposed at a position connected to a sound field space of the sound generated by the fan, and a sum of an absorbance and a reflectivity of the silencer at a resonance frequency is 10% to 43% and a standardized half-width of the silencer is more than 0.05 and 0.25 or less.

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 acoustic core may include an array of resonant cells configured as a plurality of resonant cell groups. The resonant cell groups may include a plurality of resonant cells configured as a partitioned resonant cell that include a converging resonant cell and a diverging resonant cell. The converging resonant cell and the diverging resonant cell may be defined by a plurality of cell walls integrally formed with one another and a partition integrally formed with the plurality of cell walls. The partition may at least partially delimit the converging resonant cell from the diverging resonant cell. The converging resonant cell may define an upper resonant space delimited by the partition and a top face of the array of resonant cells. The diverging resonant cell may define a lower resonant space delimited by the partition and a bottom face of the array of resonant cells.

An internal structure of a primary exhaust duct of a turbomachine, which has a primary wall allowing air to pass through orifices and forming an internal surface of the primary exhaust duct, an interior skin arranged inside the primary wall, and at least one separator of which a first edge region is attached to the interior skin and which has two geometries. A change from the first geometry to the second takes place when the temperature of the separator exceeds a first temperature, and the change from the second to the first takes place when the temperature of the separator drops below a second temperature. The coefficient of expansion of the separator is greater than that of the interior skin. The variation in the geometry of the separators depending on the temperature of the engine eases assembly at ambient temperature due to the compression of the separators.

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.

A combustor component of a combustor for combusting fuel to produce a combustion gas includes a combustion cylinder forming a passage for the combustion gas, a first acoustic device which internally includes a first cavity communicating with the passage via a first through hole formed in the combustion cylinder, a second acoustic device which is located on a radially outer side of the first acoustic device so as to cover the first acoustic device, and internally includes a second cavity communicating with the passage via a second through hole formed in the combustion cylinder, and a first communication passage causing the first cavity and an outer space of the combustion cylinder to communicate with each other without via the first through hole and the second cavity.

A structure for damping at a fluid manifold assembly for an engine is generally provided. The fluid manifold assembly includes a first walled conduit defining a first fluid passage therewithin. A flow of fluid defining a first frequency is permitted through the first fluid passage. A second walled conduit includes a pair of first portions each coupled to the first walled conduit. A second portion is coupled to the pair of first portions. A second fluid passage is defined through the first portion and the second portion in fluid communication with the first fluid passage. The flow of fluid is permitted through the second fluid passage at a second frequency approximately 180 degrees out of phase from the first frequency.

An acoustic damper for a rotary machine includes at least one wall, at least one inlet, at least one outlet, at least one separating wall, and at least one neck. The wall extends from the back side of a combustor front panel and defines a damping chamber. The inlet is defined within the wall and is oriented to channel a flow of air into the damping chamber. The outlet is defined within the back side of the front panel. The separating wall is oriented to separate the damping chamber into a first volume and a second volume. The first volume of the damping chamber is configured to damp an acoustic pressure oscillation at a first frequency. The second volume of the damping chamber is configured to damp the acoustic pressure oscillation at a second frequency. The neck extends through the separating wall and is axially offset from the outlet.