Abstract: The gas turbine engine includes a fluid system fluidly connecting at least two components of the gas turbine engine, and a tunable resonator in fluid flow communication with the fluid system. The tunable resonator has a resonating volume that varies as a function of a volume of an inflatable member located inside the tunable resonator. The inflatable member having a means for varying the volume of the inflatable member, to thereby tune the resonating volume to a selected frequency of pressure fluctuations or acoustic waves within the fluid system.

Abstract: The gas turbine engine including, in serial flow communication, a compressor, a combustor, a turbine, and a fluid system fluidly connecting at least two components of the gas turbine engine, also includes a tunable resonator in fluid flow communication with the fluid system, the tunable resonator. The tunable resonator has a resonating volume that varies as a function of a volume of an inflatable member located inside the tunable resonator. The inflatable member having a means for varying the volume of the inflatable member, to thereby tune the resonating volume to a selected frequency of pressure fluctuations or acoustic waves within the fluid system.

Abstract: Herein provided are methods and systems for reducing an acoustic signature of a gas turbine engine. An acceleration command for the engine is received. In response to receiving the acceleration command: a fuel flow to the engine is increased for a first predetermined time period; subsequent to the first predetermined time period, the fuel flow to the engine is reduced for a second predetermined time period; and subsequent to the second predetermined time period, the fuel flow to the engine is increased for a third time period.

Abstract: The gas turbine engine including, in serial flow communication, a compressor, a combustor, a turbine, and a fluid system fluidly connecting at least two components of the gas turbine engine, also includes a tunable resonator in fluid flow communication with the fluid system, the tunable resonator. The tunable resonator has a resonating volume that varies as a function of a volume of an inflatable member located inside the tunable resonator. The inflatable member having a means for varying the volume of the inflatable member, to thereby tune the resonating volume to a selected frequency of pressure fluctuations or acoustic waves within the fluid system.

Abstract: The gas turbine has a plurality of inlet guide vanes each having a blade having a leading edge, a trailing edge, a span extending along the leading edge, and pivot members at opposite ends of the leading edge, and being pivotally mounted across the radial-to-axial intake via the pivot members, the pivot axis extending axially across a radial portion of the radial-to-axial intake. The plurality of inlet guide vanes include a plurality of first inlet guide vanes, and a plurality of second inlet guide vanes, the second inlet guide vanes having a trailing edge recess differing from the corresponding portion of the first inlet guide vanes. During operation, when the inlet guide vanes are pivoted past a given angle toward the tangential orientation, a radial flow of gas is allowed through the trailing edge recesses to avoid or impede vortex whistle.

Abstract: A transfer duct and an associated active tip clearance control system of a gas turbine engine are disclosed. In one embodiment, the duct comprises: an upstream duct portion for fluid communication with an air source; a downstream duct portion for fluid communication with a manifold for directing the air toward a rotor case; and a noise-mitigating device disposed between the upstream duct portion and the downstream duct portion. The duct may define an abrupt change in internal cross sectional area between the upstream duct portion and the noise-mitigating device.

Abstract: A bleed air system is disclosed for a turbofan engine having a bypass duct. The bleed air system includes a bleed air conduit having an inlet end connected to the bypass duct and a bleed air flow control valve disposed downstream of the inlet end, and a louver assembly disposed within the opening at inlet end of the bleed air conduit. The louver assembly includes an airfoil-shaped louver blade which extends across the opening in a direction transverse to the flow direction within the bypass duct. A reinforcing rib is attached to the louver blade and extends across the louver assembly in a direction generally parallel to the flow direction.

Abstract: A surface-increasing feature system for a gas turbine engine comprising deployable surface-increasing features such as chevrons each defined by panels connected to a deployment mechanism providing a translational actuation to deploy said deployable surface-increasing feature from a stowed configuration concealed fore of a trailing edge of a case of the gas turbine engine, to a deployed configuration extending beyond the trailing edge. Joints provide one or more degree of freedom for the first panel and the second panel relative to the deployment mechanism. A guide operatively contacts the deployable surface-increasing feature to rotatably displace the first panel and the second panel away from one another in the at least one degree of freedom in response to movement induced by the translational actuation from the stowed configuration to the deployed configuration.

Abstract: A deployment mechanism for inflatable surface-increasing features a gas turbine exhaust case comprising a plurality of inflatable surface-increasing features adapted to be circumferentially distributed within the gas turbine exhaust case at a trailing edge thereof. The inflatable surface-increasing features are inflatable from a stowed configuration in which the inflatable surface-increasing features are substantially concealed fore of the trailing edge, to a deployed configuration in which the inflatable surface-increasing features extend beyond the trailing edge. A pressurizing system in fluid communication with the plurality of chevrons inflates and deflates the inflatable surface-increasing features.