Abstract: A turbofan engine is disclosed having a bypass duct with an asymmetry in aerodynamic profile caused by a local obstruction in the bypass duct. The engine comprises stator vanes circumferentially spaced-apart around a circumference of the bypass duct. A first group of adjacent stator vanes includes a majority of the plurality of stator vanes and are arranged in a first circumferential sector of the bypass duct and have equal stagger angles. A second group of adjacent stator vanes includes a minority of the plurality of stator vanes and are arranged in a second circumferential sector circumferentially positioned relative to the local obstruction. The stator vanes of the second group have stagger angles different from the stagger angles of the stator vanes of the first group.

Abstract: A blade for a compressor rotor including a blade root at a first end of the blade connected to the compressor rotor and a blade tip extending from second end of the blade. The blade tip extends up to 20% of a span of the blade from the second end towards the first end. The blade tip is disposed such that a first segment of the blade tip defines a positive dihedral angle and a second segment of the blade tip defines a negative dihedral angle. The positive and negative dihedral angles defining a twist of the blade tip relative to the face of the blade, wherein the blade remains untwisted along the span from outside of the blade tip.

Abstract: Compressor stators (22) for gas turbine engines (10) are disclosed. An exemplary compressor stator (22) comprises a circumferential array of stator vanes (28) and a shroud (24, 26) for supporting the stator vanes (28). The shroud (24, 26) has a circumferentially extending inner endwall (30, 32) exposed to an annular gas path (20) of the compressor (14). The endwall (30, 32) has a circumferentially uniform axial cross-sectional profile (42). The axial cross-sectional profile (42) comprises at least one deviation (48, 50) from a nominal axial cross-sectional profile (44) defining an overall shape of the annular gas path (20). The at least one deviation comprises a concave deviation (48) and a convex deviation (50).

Abstract: A gas turbine engine compressor includes a rotor defining a central axis of rotation and a plurality of blades which project into an annular compressor gas flow passage, and a shroud circumferentially surrounding the rotor and having a radially inner surface adjacent to the blade tips. Bleed holes extend through the shroud adjacent the blade tips, each of the bleed holes having an inlet end disposed in the shroud radially inner surface and an outlet end disposed in a shroud radially outer surface. Bleed air removed from the annular gas flow passage flows through the bleed holes from the inlet to the outlet ends. The outlet end of each bleed hole is located circumferentially upstream of the inlet end relative to a direction of rotational flow in the annular gas flow passage driven by a direction of rotation of the rotor.

Abstract: A centrifugal compressor having at least a diffuser is disclosed. The diffuser has an annular diffuser body having circumferentially spaced apart diffuser passages defining fluid paths through the diffuser body. The diffuser also has a plurality of diffusion members mounted to the annular diffuser body. Each diffusion member has a member inlet in fluid communication with a diffuser passage and a member outlet. Each diffusion member defines an aerodynamic throat disposed between the member inlet and the member outlet. The diffuser also has a fluid injection assembly with multiple injection conduits. Each injection conduit extends between a conduit inlet configured to receive a flow of compressible fluid from a supply and a conduit outlet communicating with a corresponding diffusion member downstream of the aerodynamic throat. The compressible fluid is injected through the conduit outlet into the diffusion members.

Abstract: A fan for a turbofan gas turbine engine having a low hub-to-tip ratio is disclosed. The fan includes a rotor hub and a plurality of radially extending fan blades. Each fan blade defines a hub radius (RHUB), which is the radius of the leading edge at the hub relative to a centerline of the fan, and a tip radius (RTIP), which is the radius of the leading edge at a tip of the fan blade relative to the centerline of the fan. The ratio of the hub radius to the tip radius (RHUB/RTIP) is less than 0.29. In a particular embodiment, this ratio is between 0.25 and 0.29. In another particular embodiment, this ratio is less than 0.25.

Abstract: A compressor rotor, such as a fan, for a gas turbine engine is described which includes alternating at least first and second blade types. The leading edge of the second blade types includes a leading edge tip cutback extending to the blade tip thereof. The leading edge tip cutback of the second blade type defines a chord length at the blade tip of the second blade types that is less than that of the first blades types. The first and second blade types generate different shock patterns when the fan or compressor rotor operates in supersonic flow regimes.

Abstract: A compressor for a gas turbine engine having a bleed air recirculation system includes a plurality of bleed holes extending through the shroud at a first axial location thereon substantially adjacent the blade tips. The bleed holes have a closed outer perimeter along their complete length. An annular bleed cavity surrounds the shroud and is in communication with outlet openings of the bleed holes. The bleed holes provide communication between the main gas flow passage and the bleed cavity. The bleed cavity includes exit passages having outlets disposed in the shroud at a second axial location which is upstream of both the first axial location and the leading edge of the blades of the rotor. Bleed air is passively bled from the main gas flow passage via the bleed holes, recirculated through the bleed cavity and re-injected back into the main gas flow passage at the second axial location.

Abstract: A gas turbine engine is described having a rotor with a plurality of rotor blades each extending radially between a blade root to a blade tip and axially between a leading edge and a trailing edge. An annular casing body housing the rotor blades includes an abradable segment of the inner surface facing the blade tips and having an abradable member. The abradable segment having one or more annular grooves, extending into the casing body from an inner surface thereof, and including an edge groove axially aligned with and facing the leading edge or the trailing edge of the rotor blades. The edge groove extends axially between a first position on the inner surface upstream of the leading edge or the trailing edge, and a second position on the inner surface downstream of the leading edge or the trailing edge.

Abstract: A fan for a turbofan gas turbine engine having a low hub-to-tip ratio is disclosed. The fan includes a rotor hub and a plurality of radially extending fan blades. Each fan blade defines a hub radius (RHUB), which is the radius of the leading edge at the hub relative to a centerline of the fan, and a tip radius (RTIP), which is the radius of the leading edge at a tip of the fan blade relative to the centerline of the fan. The ratio of the hub radius to the tip radius (RHUB/RTIP) is less than 0.29. In a particular embodiment, this ratio is between 0.25 and 0.29. In another particular embodiment, this ratio is less than 0.25.

Abstract: A compressor rotor for a gas turbine engine is described which includes sets of blades having different airfoil thickness distributions, each including a frequency modifier forming a thickness differential relative to a baseline blade thickness. The frequency modifiers provide different natural vibration frequencies for each of the blades, and facilitate modifying natural vibration frequency separation between adjacent blades of the compressor rotor.

Abstract: An annular casing for a rotor of a gas turbine engine includes a casing treatment having at least one groove defined in the annular casing wall with an open end defined in an inner surface of the annular casing wall, and a perforated sheet overlapping the open end of the at least one groove. The perforated sheet includes a plurality of apertures therethrough in fluid communication with the at least one groove. A method of reducing flow losses through a flow path having a rotor with a plurality of rotating blades extending therethrough is also presented.

Abstract: A gas turbine engine includes rotor having a hub, and a plurality of blades extending generally radially from the hub. Each of the blades has an airfoil portion. The airfoil portion has a leading edge and a trailing edge defining a chordwise direction, and a root and a tip defining a spanwise direction. Only a sub-set of the blades has a cutback at at least one of the trailing edge and the leading edge. A method of designing and a method of assembling a rotor having noise reduction properties in a gas turbine engine is also presented.

Abstract: A fan for a turbofan gas turbine engine having a low hub-to-tip ratio is disclosed. The fan includes a rotor hub and a plurality of radially extending fan blades. Each fan blade defines a hub radius (RHUB), which is the radius of the leading edge at the hub relative to a centerline of the fan, and a tip radius (RTIP), which is the radius of the leading edge at a tip of the fan blade relative to the centerline of the fan. The ratio of the hub radius to the tip radius (RHUB/RTIP) is less than 0.29. In a particular embodiment, this ratio is between 0.25 and 0.29. In another particular embodiment, this ratio is less than 0.25.

Abstract: A fan for a turbofan gas turbine engine, the fan comprising a rotor hub and a plurality of radially extending fan blades integral with the hub to form an integrally bladed rotor. Each fan blade defines a leading edge. A hub radius (RHUB) is the radius of the leading edge at the hub relative to a centerline of the fan. A tip radius (RTIP) is the radius of the leading edge at a tip of the fan blade relative to the centerline of the fan. The ratio of the hub radius to the tip radius (RHUB/RTIP) is at least less than 0.29. In a particular embodiment, this ratio is between 0.25 and 0.29. In another particular embodiment, this ratio is less than or equal to 0.25.

Abstract: An inlet for a turbofan engine, including an inlet wall surrounding an inlet flow path. The inlet wall extends axially from an upstream end to a downstream end adjacent the fan. The inlet wall has a shape defining a plurality of teeth circumferentially spaced around the inlet. The teeth extend axially and project radially inwardly toward the central longitudinal axis. A central portion of the inlet flow path has a cross-sectional dimension measured diametrically between opposed teeth, the cross-sectional dimension varying along the axial direction. The central portion defines a geometric throat at a minimum value of the cross-sectional dimension. The inlet wall is shaped so that the geometric throat is axially spaced from the upstream end and the downstream end. A gas turbine engine and a method of shielding tips of fan blades from impact by an object having a predetermined minimum dimension are also discussed.

Abstract: A turbofan engine including an axially extending inlet wall surrounding an inlet flow path. A radial distance between the inlet wall and the inner wall adjacent the fan defines a downstream height of the inlet flow path. A plurality of vanes are circumferentially spaced around the inlet, each of the vanes extending radially inwardly from the inlet wall, a maximum radial distance between a tip of each of the vanes and the inlet wall defining a maximum height of the vane. The maximum height of the vane is at most 50% of the downstream height of the flow path. In another embodiment, the maximum height of the vane is at most 50% of the maximum fan blade span. A method of reducing a relative Mach number at fan blade tips is also discussed.

Abstract: A centrifugal compressor having at least a diffuser is disclosed. The diffuser has an annular diffuser body having circumferentially spaced apart diffuser passages defining fluid paths through the diffuser body. The diffuser also has a plurality of diffusion members mounted to the annular diffuser body. Each diffusion member has a member inlet in fluid communication with a diffuser passage and a member outlet. Each diffusion member defines an aerodynamic throat disposed between the member inlet and the member outlet. The diffuser also has a fluid injection assembly with multiple injection conduits. Each injection conduit extends between a conduit inlet configured to receive a flow of compressible fluid from a supply and a conduit outlet communicating with a corresponding diffusion member downstream of the aerodynamic throat. The compressible fluid is injected through the conduit outlet into the diffusion members.

Abstract: A blade for a compressor rotor comprises a blade root at a first end of the blade extending from a rotor body of the compressor, and a blade tip at a second end of the blade. The first end and the second end are disposed on a span of the blade. The blade root and the blade tip define a face of the blade between them. The blade tip comprises a first extremity and a second extremity. The blade tip is disposed such that a first segment of the blade tip defines a positive dihedral angle with the face of the blade. The first segment extends from a first point in the blade tip to the first extremity of the blade tip. A second segment of the blade tip defines a negative dihedral angle with the face of the blade. The second segment extends from a second point in the blade tip to the second extremity of the blade tip.

Abstract: A compressor for a gas turbine engine with variable inlet guide vanes each defining an airfoil portion twisted such that at each location of the airfoil portion along the pivot axis, an angle is defined between a respective chord extending between the leading and trailing edges and a same reference plane containing the pivot axis and extending radially with respect to the compressor. The angle, which is measured along a direction of rotation of the rotor, varies from a minimum value near the hub side wall to a maximum value near the shroud side wall. A method of reducing vortex whistle in a radial inlet of a compressor is also provided.