Rolls-royce Corporation

Peter Rowland Beckford

Simon Read

Ian Colin Deuchar Care

David S Knott

Alison Jane McMillan

Stephen John Booth

David M Lambert

David R Midgelow

Daniel John Allan Swan

Caroline Halliday

Katherine E Lomas

Katherine Ellen Lomas

A fan blade for a gas turbine engine has an aerofoil part and a root part. The root part includes a root former; the root former includes a zone of weakness, which reduces the ability of the root part to withstand an impact force. Thus, in an impact situation in which the fan blade has separated from the fan rotor and the fan blade has itself separated into fragments, the root part will fracture or buckle more easily than would be the case with conventional arrangements. This will lower the impact force of the root part upon the fan casing, thus permitting the fan casing to be designed to withstand lower impact forces. The fan casing can therefore be made lighter, and cheaper, than in conventional arrangements.

Blade

International regulations for aerofoils within gas turbine engines require the safe containment of a released aerofoil. The blade fragments must be contained within an engine casing. Smaller fragments will generally be easier to contain within the casing and therefore reduce the weight of that casing. However introducing lines of weakness may result in cavities and holes which are subject to moisture ingress and problems associated therewith. By providing a root section which incorporates a core having shear surfaces, blades can be designed which in normal use are subject to compressive loads and remain operational, but when subject to impact loads or bending forces create tension forces which cause fragmentation along the shear surfaces after initial energy losses by slippage. By providing the shear surfaces in cores their location is encapsulated avoiding problems with moisture ingress.

Blade and a method for making a blade

A fan blade for a gas turbine engine has an aerofoil part and a root part. The root part includes a root former; the root formerincludes a zone of weakness, which reduces the ability of the root part to withstand an impact force. Thus, in an impact situation in which the fan blade has separated from the fan rotor and the fan blade has itself separated into fragments, the root part will fracture or buckle more easily than would be the case with conventional arrangements. This will lower the impact force of the root part upon the fan casing, thus permitting the fan casing to be designed to withstand lower impact forces. The fan casing can therefore be made lighter, and cheaper, than in conventional arrangements.

Blade assemblies are provided in a number of forms. These blade assemblies may have blades secured to disks (blisk), rings (bling) and drums (blum). The blades and/or the rotor elements formed by these rings, drums or disks can fragment and it is necessary to contain such fragments within a casing. Impact energy has a significant effect upon the necessary thickness of the casing to ensure containment. By providing blades as well as rotor elements which incorporate discontinuities which provide flexing under impact, energy is absorbed prior to further fragmentation upon impact engagement with a casing surface; flexing is about the discontinuity. In such circumstances casings may be thinner and therefore significant weight savings achieved with regard to aircraft incorporating gas turbine engines having blade assemblies with discontinuities.

Blade assembly

A blade arrangement () comprises an aerofoil () and a mounting support () to mount the blade arrangement to a disc. The aerofoil () is supported on the mounting support (). The aerofoil () comprises a plurality of elongate aerofoil portions () arranged adjacent one another to provide the aerofoil.

Turbine blade

A blade assembly for a rotary component comprises an aerofoil member and a displacement apparatus on the aerofoil member for displacing a detached first portion of the aerofoil member in a rearward direction relative to a second portion of the aerofoil member. On failure of the aerofoil member, the displacement apparatus displaces the first portion from the second portion in the rearward direction.

An aerofoilis provided by layers of material with at least one layer of the material being relatively stiff while other layers of material are less dense but are subject to less stress within the aerofoil. Thus, by judicious positioning of the stiffer layers of material an effective operational aerofoil is achieved, with the other layers of material having a lower stiffness but also lower mass so that the overall mass of the aerofoil is reduced. It will be understood by appropriate positioning of the layers of material it is possible to tune the aerofoil for deformation and vibrational response effects, particularly under impact loading from bird strikes etc.

Aerofoil

A blade for a gas turbine engine includes a root portion, an aerofoil portion and a transition portion between the root portion and the aerofoil portion. The aerofoil portion and the transition portion are defined by first and second wall members, the first and second wall members being secured together in the transition portion and each having an outer surface. The outer surface of at least one of the first and second wall members is generally concave in the transition portion in a radial direction of the blade.

Blades

A fan blade containment assembly () for a turbofan gas turbine engine () comprises a cylindrical, or frustoconical, casing () arranged to surround an arrangement of fan blades (). At least one hollow tubular member () is arranged radially within and secured to the casing () and the at least one hollow tubular member () contains a filler material (). The at least one hollow tubular member () extends circumferentially. The hollow tubular member () is helical and the axial spacing between the adjacent turns of the tubular member () varies and the density of the filler material () varies in order to match the severity of the impact expected at each axial location along the casingof the fan blade containment assembly ().

Rotor blade containment assembly for a gas turbine engine

An aerofoilfor a gas turbine engine (, FIG.) comprises a cavity, a cellular materiallocated in the cavityfor stiffening the aerofoil, and a vibration damping mediumlocated in the cavityfor damping the aerofoil. The cellular materialis preferably a metal foam bonded to the inner surfaceof the hollow aerofoil, and the vibration damping mediumis preferably a viscoelastic material. Various methods for fabricating the aerofoilare also described.

Aerofoils for gas turbine engines

A stage of fan aerofoils () lies within a fan cowl (). The fan duct () is defined in part by a hard casing () that in turn surrounds aerofoils (). Hard casing () includes wedge members () that fill the annular gap between ring () and an outer ring (). In the event of an aerofoil () breaking off, the hard ring () and wedges () absorb sufficient of the kinetic energy expended by the broken aerofoil (), as to prevent it passing through outer ring () on to the fan cowl ().

Aerofoil containment structure

Two metal blocks () are welded to respective metal sheets () to form sealed assemblies. The sealed assemblies are then diffusion bonded together to form two metal preforms (). The thick ends () and () of the metal sheets () and the metal blocks () are hot formed so that a continuation of the plane X of the first surfaces () of the metal sheets () extends through and across the metal blocks (). The metal preforms () are machined to remove the portion of the metal blocks () extending above the first surfaces () of the metal sheets () respectively. The metal preforms () and a metal sheet () are assembled into a stack (). The metal preforms () and the metal sheet () are diffusion bonded together and then superplastically formed to produce a hollow fan blade (). The method enables thinner metal workpieces with better microstructure to be used and increases the yield of metal workpieces.

Method of manufacturing an article by diffusion bonding and superplastic forming

A fan rotor assembly (30) for a gas turbine engine (10) comprises a fan rotor (32) and a plurality of radially extending fan blades (34). Each fan blade (34) has a root (64) which is retained in a corresponding groove (54) in the periphery of the hub (54) of the fan rotor (32). Each fan blade root (64) comprises four axially spaced root portions (66, 68, 70 and 72) which locate in a corresponding number of axially spaced groove portions (56, 58, 60 and 62). The flanks (94, 98) of two of the root portions (66, 70) are arranged at an angle to the axis of the fan rotor (32) and the flanks (96, 100) of the other two root portions (68, 72) are arranged at an angle in the opposite sense. The flanks (74, 76, 78 and 80) of the groove portions (56, 58, 60 and 62) are arranged at the same angle as the flanks (94, 96, 98 and 100) of the corresponding root portions (66, 68, 70 and 72). The arrangement provides improved retention of the fan blades (34) and reduces the weight of the fan blades (34) and fan rotor (32).

Rotor assembly

A rotor for a ducted fan gas turbine engine includes a rotor disc on which a number of circumferentially spaced apart blades are mounted. Wall members are positioned to bridge the space between adjacent blades. The wall members correspond in profile with the blades adjacent thereto. A seal is mounted on a side face of each wall member and is bonded to a flexible mounting which is bonded itself to the wall member. The flexible mounting has elastic properties so as to allow the seal to deflect relative to the wall member under centrifugal loading during operation.

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Derby, United Kingdom

Peter Rowland Beckford