Abstract: A method includes: obtaining a rotor having a hub and a plurality of blades protruding from the hub, the plurality of blades including first blades and second blades disposed in alternation around a central axis of the rotor, natural vibration frequencies of the first blades different from natural vibration frequencies of the second blades; determining that a difference between a first natural vibration frequency of a first blade of the first blades and a second natural vibration frequency of a second blade of the second blades is below a threshold; and modifying a shape of the first blade until the difference between the first natural vibration frequency and the second natural vibration frequency is at or above the threshold.

Abstract: The gas turbine compressor for an aircraft gas turbine engine includes a compressor rotor having a plurality of compressor blades circumferentially distributed around a hub. Each of the compressor blades has an airfoil extending radially outward from the hub to a blade tip. A circumferential row of the compressor blades includes two or more different blade types, at least one modified blade of the two or more different blade types having means for generating different shock patterns between adjacent ones of the two or more different blade types when the gas turbine compressor operates in supersonic flow regimes. The means for generating different shock patterns on the modified blade aerodynamically mistune the two or more different blade types.

Abstract: The stiffness of a rotor part is varied over its circumference to allow damper rings to effectively work in high speed applications. Circumferentially spaced-apart pockets may be defined in the rotor to create discontinuous strain to increase the force required to lock the damper ring in the groove above the centrifugal force of the ring when the rotor is rotating.

Abstract: There is disclosed a controlled gap seal for a gas turbine engine including a ring configured to be in a sealing engagement with a housing and a runner configured for rotation relative to the ring about the central axis. The runner has a runner face facing a ring face of the ring. The ring face is spaced apart from the runner face by a gap. A plurality of surface discontinuities are circumferentially distributed around the central axis on the runner face and/or the ring face. The plurality of surface discontinuities are spaced relative to one another such that a first set of adjacent surface discontinuities are circumferentially spaced from each other at a different distance than a second set of adjacent surface discontinuities. A method of using the controlled gap seal is disclosed.

Abstract: The centrifugal impeller can have a hub and a plurality of blades, each of the blades having a span extending from the hub to a tip edge, camber lines extending from an inlet edge to an outlet edge between two opposite faces, including a tip camber line extending along the tip edge and a 50% span camber line extending at 50% of the span, a thickness extending between opposite faces of each blade, the tip edge having, at a location corresponding to 5% of the tip camber line, less than 15% of the maximum thickness, each of the blades having, along the 50% span camber line, a thickness reaching at least 58% of the maximum thickness and then reducing by at least 5% of the maximum thickness within 10% of the length of the 50% span camber line.

Abstract: There is disclosed a diffuser pipe assembly having: a plurality of diffuser pipes circumferentially distributed around the central axis and configured for diffusing a flow of compressed air received from an impeller, the diffuser pipes having a diffuser conduit for directing the flow of compressed air, the diffuser conduit curving between an inlet end and an outlet end along a conduit axis, the diffuser conduit having a baseline surface, a first subset of the diffuser pipes having aero-dampers protruding from the baseline surfaces of their diffuser conduits such that the diffuser pipes of the first subset have a natural vibration frequency different than a natural vibration frequency of at least a second subset of the diffuser pipes.

Abstract: There is disclosed a controlled gap seal for a gas turbine engine. The seal has a ring annularly and continuously extending about a central axis. A runner that is configured for rotation about the central axis and rotatable relative to the ring. The runner has a face facing a face of the ring. The face of the ring is spaced apart from the face of the runner by a gap. Surface discontinuities are circumferentially distributed around the central axis. The surface discontinuities are located at specific locations and distributed in specific ways. A method of using the controlled gap seal is disclosed.

Abstract: A rotor for a gas turbine is disclosed which includes alternating first and second set of rotor blades, the first set of rotor blades having a baseline profile and the second set of rotor blades having a profile with a cutback relative to the baseline profile, the cutback defining a removed portion of the baseline profile surrounding a maximum deflection point of a selected natural vibration mode. The cutback may be a leading edge cutback at a span position located a distance away from the hub between 20% and 50% of the total span length. The selected natural vibration mode may be a natural vibration mode higher than the 1st natural vibration mode, more specifically may be the 5t? natural vibration mode.

Abstract: The centrifugal impeller can have a hub and a plurality of blades, each of the blades having a span extending from the hub to a tip edge, camber lines extending from an inlet edge to an outlet edge between two opposite faces, including a tip camber line extending along the tip edge and a 50% span camber line extending at 50% of the span, a thickness extending between opposite faces of each blade, the tip edge having, at a location corresponding to 5% of the tip camber line, less than 15% of the maximum thickness, each of the blades having, along the 50% span camber line, a thickness reaching at least 58% of the maximum thickness and then reducing by at least 5% of the maximum thickness within 10% of the length of the 50% span camber line.

Abstract: There is disclosed an assembly for a gas turbine engine that includes a bearing housing circumferentially extending around a central axis thereof and delimiting a bearing cavity for receiving a bearing therein. A controlled gap seal is secured to the bearing housing, the controlled gap seal including a ring and a runner, the runner rotatable relative to the ring about the central axis, the runner spaced apart from the ring by a gap. The gap defines a fluid passage between the bearing cavity and an environment outside the bearing cavity. At least one baffle is secured to a surface of the bearing housing oriented toward the bearing cavity. The at least one baffle is a fin protruding from the surface and extending into the bearing cavity. The at least one baffle disrupts a cylindricality of the surface. A method of operating the bearing assembly is also disclosed.

Abstract: There is disclosed a brush seal assembly including at least one annular bristle pack. The at least one annular bristle pack extends circumferentially around a central axis of the brush seal assembly. The at least one annular bristle pack has bristles extending along longitudinal axes from roots to free tips. The bristles extend toward a cylindrical plane of a the seal land. Projections of the free tips on the cylindrical plane define a bristle tip projection surface being non-axisymmetric. A method of operating a brush seal assembly is also disclosed.

Abstract: The gas turbine compressor for an aircraft gas turbine engine includes a compressor rotor having a plurality of compressor blades circumferentially distributed around a hub. Each of the compressor blades has an airfoil extending radially outward from the hub to a blade tip. A circumferential row of the compressor blades includes two or more different blade types, at least one modified blade of the two or more different blade types having means for generating different shock patterns between adjacent ones of the two or more different blade types when the gas turbine compressor operates in supersonic flow regimes. The means for generating different shock patterns on the modified blade aerodynamically mistune the two or more different blade types.

Abstract: A rotor for a gas turbine engine. The rotor includes blades circumferentially distributed around a hub. The blades have airfoils with a span defined between a root and tip, a chord defined between a leading edge and a trailing edge, and a thickness defined between a pressure side surface and suction side surface. The blades include first blades and second blades. The airfoil of the first blades has a first thickness distribution defining a first natural vibration frequency of the airfoils of the first blades. The airfoil of the second blades has a second thickness distribution defining a second natural vibration frequency different than the first natural vibration frequency. The first thickness distribution is different than the second thickness distribution along a radially-inner half of the span, and the first thickness distribution matches the second thickness distribution along a radially-outer half of the span.

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: A brush seal assembly is adapted to be operatively mounted between a stator and a rotor of a gas turbine engine. The brush seal assembly comprises a housing and a seal operatively coupled to the housing. The seal comprises at least two annular brushes each having a plurality of bristles extending away from the housing. The at least two annular brushes and the housing defines a cavity therebetween. The housing defines at least one circumferential surface within the cavity. The housing comprises at least one discontinuity defined in the at least one circumferential surface. The at least one discontinuity disrupts a continuity of annularity of the circumferential surface.

Abstract: A fan for a gas turbine engine comprises blades distributed around a hub. The blades include first and second blades, having geometric parameters and/or material properties that differ from each other to frequency mistune the fan. The blades are distributed about the hub with at least one second blade between adjacent first blades. The leading edge of the airfoil of the second blades is disposed axially aft of the corresponding leading edge of the first blades in at least a portion of the blade span.

Abstract: The diffuser pipe assembly for a compressor of a gas turbine engine includes diffuser pipes circumferentially distributed around a central axis and configured for distributing a flow of compressed air from the compressor to the combustor. Each of the diffuser pipes curving between an inlet end and an outlet end. A first subset of the diffuser pipes has a natural vibration frequency different than a natural vibration frequency of at least a second subset of the diffuser pipes. A method of operating a compressor including the diffuser pipe assembly is also disclosed.

Abstract: A rotor for a gas turbine is disclosed which includes alternating first and second set of rotor blades, the first set of rotor blades having a baseline profile and the second set of rotor blades having a profile with a cutback relative to the baseline profile, the cutback removing a portion of the baseline profile surrounding a maximum deflection point of a selected natural vibration mode. The cutback may be a tip trailing edge cutback at a span position located a distance away from the hub of at least 75% of the total span length. The selected natural vibration mode may be a natural vibration mode higher than the 1st natural vibration mode, more specifically may be the 3rd or 6th natural vibration mode.

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 rotor for a gas turbine is disclosed which includes alternating first and second set of rotor blades, the first set of rotor blades having a baseline profile and the second set of rotor blades having a profile with a cutback relative to the baseline profile, the cutback removing a portion of the baseline profile surrounding a maximum deflection point of a selected natural vibration mode. The cutback may be a leading edge cutback at a span position located a distance away from the hub between 20% and 50% of the total span length. The selected natural vibration mode may be a natural vibration mode higher than the 1st natural vibration mode, more specifically may be the 5th natural vibration mode.