Abstract: An aircraft engine, has: an upstream stator having upstream stator vanes circumferentially distributed about a central axis; and a downstream stator having downstream stator vanes circumferentially distributed about the central axis, the downstream stator located downstream of the upstream stator relative to an airflow flowing within a core gaspath of the aircraft engine, a number of the upstream stator vanes being different than a number of the downstream stator vanes, the downstream stator vanes including: a first vane made of a first material, a major portion of a leading edge of the first vane circumferentially overlapped by one of the upstream stator vanes, and a second vane made of a second material having a greater stiffness, strength, and/or ductility than that of the first material, a major portion of a leading edge of the second vane exposed via a spacing defined between two of the upstream stator vanes.

Abstract: An aircraft engine, has: an upstream stator having upstream stator vanes distributed about a central axis; and a downstream stator having downstream stator vanes distributed about the central axis, the downstream stator located downstream of the upstream stator, a number of the upstream stator vanes different than a number of the downstream stator vanes, the downstream stator vanes including: a first vane, a major portion of a leading edge of the first vane circumferentially overlapped by one of the upstream stator vanes; and a second vane differing from the first vane by a geometric parameter, the geometric parameter causing the second vane to have one or more of: a stiffness greater than that of the first vane, and a major portion of a leading edge of the second vane circumferentially overlapped by another one of the upstream stator vanes.

Abstract: An aircraft engine, has: an upstream stator having upstream stator vanes circumferentially distributed about a central axis; and a downstream stator having downstream stator vanes circumferentially distributed about the central axis, the downstream stator located downstream of the upstream stator relative to an airflow flowing within a core gaspath of the aircraft engine, a number of the upstream stator vanes being different than a number of the downstream stator vanes, the downstream stator vanes including: a first vane made of a first material, a major portion of a leading edge of the first vane circumferentially overlapped by one of the upstream stator vanes, and a second vane made of a second material having a greater stiffness, strength, and/or ductility than that of the first material, a major portion of a leading edge of the second vane exposed via a spacing defined between two of the upstream stator vanes.

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: 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: 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 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: 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 compressor rotor airfoil in a gas turbine engine is presented. Opposed pressure and suction sides are joined together at chordally opposite leading and trailing edges. The pressure and suction sides extend in a span direction from a root to a tip. A leading edge dihedral angle is defined at a point on the leading edge between a tangent to the airfoil and a vertical. The leading edge dihedral angle has a span-wise distribution. The distribution has at least one inflection point. A method of reducing a rub angle between a compressor rotor blade and a casing surrounding the blade is also presented.

Abstract: An airfoil for a gas turbine engine comprises at least three successive sections defined between a root and a tip. A first decrease of maximum thickness-to-chord ratios defined by a difference between a maximum thickness-to-chord ratio at the root and a maximum thickness-to-chord ratio at a first spanwise position, a second decrease of the maximum thickness-to-chord ratios defined by a difference between the maximum thickness-to-chord ratio at the first spanwise position and a maximum thickness-to-chord ratio at a second spanwise position, a third decrease of the maximum thickness-to-chord ratios defined by a difference between the maximum thickness-to-chord ratio at the second spanwise position and a maximum thickness-to-chord ratio at the tip, the second decrease being greater than the corresponding first and third decreases.

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: 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: 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: A rotary airfoil in a gas turbine engine is provided. The airfoil includes opposed pressure and suction sides joined together at chordally opposite leading and trailing edges. The pressure and suction sides extend in a span direction from a root to a tip. An axial component of a center of gravity of a cross-section taken chordally toward the tip of the airfoil being upstream relative to an axial component of a center of gravity of a cross-section taken chordally toward the root of the airfoil. A method for forming such blade is also presented.

Abstract: A method for repairing a blade in a gas turbine engine comprises the steps of: isolating the damage on the airfoil of the blade; forming a cut back in the shape of elongated “D” shaped recess with a pair of fillets, a depth and a longitudinal axis of the “D” shaped recess having a length along the leading or trailing edge of the airfoil; and the fillets having a respective radius.

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 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 airfoil for a gas turbine engine comprises at least three successive sections defined between a root and a tip. A first decrease of maximum thickness-to-chord ratios defined by a difference between a maximum thickness-to-chord ratio at the root and a maximum thickness-to-chord ratio at a first spanwise position, a second decrease of the maximum thickness-to-chord ratios defined by a difference between the maximum thickness-to-chord ratio at the first spanwise position and a maximum thickness-to-chord ratio at a second spanwise position, a third decrease of the maximum thickness-to-chord ratios defined by a difference between the maximum thickness-to-chord ratio at the second spanwise position and a maximum thickness-to-chord ratio at the tip, the second decrease being greater than the corresponding first and third decreases.

Abstract: A diffuser pipe for a gas turbine engine comprises a hollow pipe body including a first end, a second end fluidly connected to the first end, and at least one flattened area proximate to the second end. A ring is connected to the second end. The ring is an outlet of the diffuser pipe. At least one stiffener is disposed on the at least one flattened area. The ring and the at least one stiffener reduce vibratory stresses at the second end of the pipe body. A method of manufacturing a diffuser pipe of a gas turbine engine is also presented.