Methods, apparatus, systems, and articles of manufacture to provide damping of an airfoil are disclosed. An example airfoil is disposed in a flow path, the airfoil including a shell defining an exterior surface of the airfoil and forming a cavity in an interior surface of the airfoil, and a lattice damper disposed in the cavity, the lattice damper to reduce vibrational loads exerted on the airfoil.

An accumulator designed to damp the pressure waves of the hydraulic shocks originating in a downstream section of a duct is arranged inside the duct, with the opening of the accumulator pointing downstream. This results in excellent absorption of the pressure wave and protection of the circuit from possible accumulations of air, water or ice, there being no areas where the flow stagnates. Immersing the accumulator in the flow also makes it possible to ensure that the equipment is protected in the event of a fire.

A ceiling fan assembly having a motor with a rotor with multiple blade mounts, multiple blades having a removable blade tip, a balancing weight mount carried by the multiple blades and covered by the removable tip, and where each of the multiple blades are pre-balanced and indexed to a corresponding one of the multiple blade mounts.

An engine vibration monitoring and control system includes an aircraft autopilot and a flight management system (FMS). The FMS is in operable communication with the aircraft autopilot and is configured to determine when the aircraft autopilot is engaged and disengaged. The FMS is also adapted to receive vibration data from an engine vibration data source and is configured, upon determining that the aircraft autopilot is engaged, to: process the vibration data to determine when engine vibrations exceed one or more first thresholds, and when the engine vibrations exceed the one or more first thresholds, supply commands to the autopilot that cause the autopilot to take corrective actions to reduce the engine vibrations below the one or more first thresholds.

The invention relates to a nubomachine with a longitudinal axis, comprising two, respectively upstream (122) and downstream, coaxial outer propellers (122), characterised in that at least some of the blades (148) of the upstream propeller (122) comprise at least one internal air circulation chimney (150) that communicates with air-bleeding openings (152) in tire boundary layers of the blades (148), and communicates with air outflow openings (158) on the radially outer end thereof, the air-bleeding openings (152) leading to opening inlets (152a) on tire passive surfaces (156) of the blades (148), the inlets (152a) of the air-bleeding openings being radially arranged in an area (H1) contained between 10% and 45% of the radial dimension (H2) of the blades (148), measured above turd from the radial height of the blades for which the tangent of the leading edge (138) of the blades is orthogonal to the longitudinal axis, and the inlets (152a) of the air bleeding openings being arranged in an area contained between 0% and 30% of the local chord of the blades (148), measured at the level of said inlets (152a) and from the leading edges (138) of tire blades (148).

Compliant mounting systems, devices, and methods for mounting a vehicle engine to a vehicle structure or base include a top mount, a lower mount, a center trunnion mount, and an aft mount which are configured to react forces transmitted by the engine to the vehicle structure. Metallic and elastomeric elements can provide vibrational and force isolation characteristics. Stops (e.g., snubbing elements) allow for a specific range of motion before internal mount structures contact each other to act as a conventional hard mount. Fluid elements and compressible gas-filled spaces/bladders may be incorporated to provide fluid damping behaviors to complement the metallic and elastomeric elements.

A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine that has high efficiency provides low noise, in particular from the fan and the turbine that drives the fan. Values are defined for a noise parameter NP that results in a gas turbine engine having reduced combined fan and turbine noise.

A centrifugal fan noise-lowering structure includes a frame having an upper and a lower cover and a sidewall, which together internally define a receiving space communicable with an air inlet and an air outlet of the frame; a stator assembly located in the receiving space and fixedly mounted on the lower cover; and a rotor assembly correspondingly assembled to the stator assembly. The receiving space is internally defined a high pressure zone and a low pressure zone. The upper cover is provided with an airflow passage, which has an inlet located at a position corresponding to the high pressure zone, and an outlet located at a position corresponding to the low pressure zone. With the airflow passage, air in the high pressure zone can be guided to jet out to the low pressure zone to thereby reduce noise produced by the centrifugal fan during its operation.

Resonating patch for acoustic treatment comprising a resonant plate, a transducer and an electrical circuit electrically connected to the transducer, the resonant plate comprising a peripheral strip extending along the perimeter of the resonant plate.

The patch comprises cutouts together defining deformable lamellae having at least one end connected to the peripheral strip.

An acoustic panel includes a front skin comprising a plurality of apertures, a back skin, and a core positioned between the front skin and the back skin. The core includes at least one primary core portion including a honeycomb structure defining a plurality of cavities extending from the front skin to the back skin. The core further includes a secondary core portion external to the at least one primary core portion and including a foam structure extending from the front skin to the back skin.