Abstract: A noise-attenuating covering configured for example for a pipe for guiding gases along a gas path. The covering includes a wall defining the gas path and at least one resonance cavity, the wall being pierced with holes for fluid communication between the gas path and the resonance cavity to attenuate noise. The holes have substantially identical diameters and, since the pipe is arranged to guide the gases in the downstream direction, a number of the openings per wall surface unit decreases continuously along the gas path in the downstream direction, such as to confer on the wall substantially constant acoustic resistance along the gas path, for which the noise attenuation is optimized along the gas path.

Abstract: A monitoring device for monitoring rotors of turbines, including: an acoustic sensor; and a sound waveguide for connecting the acoustic sensor to a sensing point close to the rotor of the turbine. The acoustic sensor is configured to detect, as soundwaves, pressure fluctuations due to pressure differences between suction and pressure sides of blades of the rotor as they move past in proximity of a sensing point. A method of monitoring a rotor of a turbine transmits pressure fluctuations due to pressure differences between suction sides and pressure sides of blades of the rotor going past the proximity of a sensing point by a sound waveguide to an acoustic sensor to be picked up as soundwaves.

Abstract: A device for ejecting gas from a gas turbine engine, which includes: an outer wall and an inner wall defining a gas flow path therebetween, the inner wall forming a central body defining an inner cavity, the outer wall being perforated and communicating with at least one outer resonance cavity for attenuating noise in a first range of sound frequencies; and a mechanism for placing the outer and inner cavities in fluid communication, extending through the gas flow path, the inner cavity thus forming a resonance cavity for attenuating the noise in a second range of sound frequencies. The device can, for example, be used to attenuate two ranges of sound frequencies.

Abstract: A noise-attenuating covering configured for example for a pipe for guiding gases along a gas path. The covering includes a wall defining the gas path and at least one resonance cavity, the wall being pierced with holes for fluid communication between the gas path and the resonance cavity to attenuate noise. The holes have substantially identical diameters and, since the pipe is arranged to guide the gases in the downstream direction, a number of the openings per wall surface unit decreases continuously along the gas path in the downstream direction, such as to confer on the wall substantially constant acoustic resistance along the gas path, for which the noise attenuation is optimized along the gas path.