The invention relates to a method for fabricating a gas turbine engine component comprising an inner ring, an outer ring and at least one strut connecting the inner ring with the outer ring. The invention in particular relates to a method of forming a strut connecting the inner and outer ring. The invention also relates to a gas turbine engine component comprising an inner ring, an outer ring and a set of struts connecting the inner ring with the outer ring.
A gas turbine engine may be used as a jet engine. The term jet engine includes various types of engines, which admit air at relatively low velocity, heat it by combustion and shoot it out at a much higher velocity. Accommodated within the term jet engine are, for example, turbojet engines and turbo-fan engines. The invention will below be described for a turbo-fan engine, but may of course also be used for other engine types.
An aircraft engine of the turbofan type generally comprises a forward fan and booster compressor, a middle core engine, and an aft low pressure power turbine. The core engine comprises a high pressure compressor, a combustor and a high pressure turbine in a serial relationship. The high pressure compressor and high pressure turbine of the core engine are interconnected by a high pressure shaft. The high-pressure compressor, turbine and shaft essentially form a high pressure rotor. The high-pressure compressor is rotatably driven to compress air entering the core engine to a relatively high pressure. This high pressure air is then mixed with fuel in the combustor and ignited to form a high energy gas stream. The gas stream flows aft and passes through the high-pressure turbine, rotatably driving it and the high pressure shaft which, in turn, rotatably drives the high pressure compressor.
The gas stream leaving the high pressure turbine is expanded through a second or low pressure turbine. The low pressure turbine rotatably drives the fan and booster compressor via a low pressure shaft, all of which form the low pressure rotor. The low pressure shaft extends through the high pressure rotor. In civil applications most of the thrust produced is generated by the fan while in military applications most of the thrust produced is generated by the low and high pressure turbines. Engine frames are used to support and carry the bearings, which in turn, rotatably support the rotors. Conventional turbo fan engines have a fan frame, a mid-frame and an aft turbine frame.
These frames may be constructed by a gas turbine engine component comprising an inner ring, an outer ring and at least one strut connecting the inner ring with the outer ring. U.S. Pat. No. 7,370,467 discloses a method for connecting an outer ring to an inner ring in a frame. From
It is desirable to facilitate assembly of a gas turbine engine component. It is also desirable to facilitate assembly of a gas turbine engine component by facilitating mounting of a strut which connects an inner ring to an outer ring and thereby secures the inner ring to the outer ring.
According to an aspect of the invention, a gas turbine engine component including an inner ring, an outer ring and at least one strut connecting the inner ring with the outer ring is fabricated in a method including the steps of:
The method step of connecting the inner ring to the outer ring via the load carrying edge of the strut may be performed by casting an integrated gas turbine component structure in a single piece. The integrated gas turbine component structure includes the inner ring, the outer ring and said load carrying edge of the strut. In this embodiment the side face component of the strut is attached in abutment with said load carrying edge after the integrated gas turbine component is removed from its casting mould. In this stage the inner ring is attached to the outer ring.
Alternatively, the method step of connecting the inner ring to the outer ring via the load carrying edge of the strut may be performed by attaching the inner ring to the outer ring via the load carrying edge of the strut.
This may be performed by connecting said inner ring to said outer ring via the load carrying edge of the strut by welding said load carrying edge to connect the inner ring to the outer ring. Attachment of the load carrying edge to the inner and outer ring may be performed by welding. The load carrying edge may be constituted by a pillar which is connected directly to the outer and inner ring. The load carrying edge may include stubs located either of the inner or outer ring, or on both of them. Here, with a stub is intended a protrusion being integral with or secured to the inner and/or outer ring. The load carrying edge may alternatively include a stub located on the inner and/or outer ring and a pillar secured to the stub or stubs. With a strut is included a complete structure including a leading edge, possibly a trailing edge and a side face component connecting the leading edge with the trailing edge. A strut is generally designed to transfer load from the inner ring to the outer ring. The strut is generally designed with a streamline contour. The strut may additionally function to guide the flow, thus the strut may also constitute a vane.
Since a major portion of the load imposed on the strut is transferred via the load carrying edge, it is sufficient to attach this part of the strut to the inner and outer ring. Hence, the attachment of the inner ring to the outer ring may be performed by a weld seam at the load carrying edge or by forming the inner ring, outer ring and the load carrying edge as an integrated unit in a casting process. Since the passage between the inner ring and outer ring may be very narrow in certain parts of the engine, room for access by welding tool to secure the inner ring to the outer ring with a weld seam along a complete axial extension of the strut may not always be present. By using the proposed method to attach the inner ring to the outer ring via a load carrying edge, sufficient room for a welding tool is present, due to that the load carrying edge is located relatively closely to an entry or exit of a gas channel formed in the space between the inner and outer rings. At least one weld seam is then performed around the load carrying leading edge so that it is connected to the inner ring and/or the outer ring. The attachment of the inner ring to the outer ring via the load carrying edge may be performed by creating a weld seam between a pillar constituting the load carrying edge and the inner and outer ring. The attachment may also be performing uniting a stub present on the inner or the outer ring strut with a corresponding stub on the other ring, directly to the other ring or via a pillar. A strong weld seam may be created for the load carrying edge, since the edge is located relatively close to the entry or exit of the gas channel formed between the inner and outer rings and access for a welding tool is facilitated such that it is possible to weld around the complete contour of the load carrying edge, at the location or locations where parts of the load carrying edge are united by a weld seam, in order to attach the inner ring to the outer ring. Hence a structural rigidity of the gas turbine engine component may be maintained without requiring that the'side face component being welded to the outer and inner rings at an upper and lower radial rim of the side face component. The strut may thereafter be completed by attaching a side face component of a strut in abutment with the load carrying edge after the step of attaching said inner to said outer ring via said load carrying edge has been performed.
The side face component is preferably attached to the load carrying edge via welding. At least one weld seam is then performed in a radial direction of the component along the load carrying edge between the inner ring and the outer ring. The step of attaching said inner ring to said outer ring via a load carrying edge of a strut may include attachment of the inner ring to the outer ring via a load carrying leading edge and a load carrying trailing edge. The load carrying leading edge and load carrying trailing edge are positioned at a distance relative to each other so as to leave a space in between them. The step of attaching a side face component of a strut in abutment with the load carrying edge includes attachment of the side face component of a strut in the space and in abutment with both the load carrying leading edge and the load carrying trailing edge.
The side face component are thus in this embodiment introduced after the inner and outer rings have been attached to each other via both the leading and trailing edges. By waiting with attaching the side face component to the leading and trailing edges until after the inner and outer ring have been secured to each other via the leading and trailing edges, ample room for access of a welding tool to secure the leading and trailing edges to the inner and outer ring is ensured.
The leading and trailing edges may be formed of solid metal components that are welded to the inner and outer ring.
The side face component may be pushed in a radial direction through an opening arranged in said inner or outer ring to a position adjacent to said load carrying edge before the side face component is attached to the load carrying edge.
In an embodiment of the invention, the side face component is formed of a sheet metal structure. The sheet metal structure may be formed into the side face component by folding a sheet metal blank to form a first and a second side face, each forming a portion of a side face of the strut; a first end face connected with the first and second side face of side face component, the first end face being adapted to bear against an inner surface of the leading or trailing edge; and one or two end portions the one or each being connected with one of the first and second side face of the mid component, the end portion or portions being adapted to bear against an inner surface of the other of the leading or trailing edge.
In another embodiment of the invention, the side face component may be formed by an extruded profile including a first and a second side face of the strut and a first and a second end face connected with the first and second side face of the strut, the first and second end faces being adapted to bear against inner surfaces of the leading or trailing edges.
The side face component may be pushed into a space defined by the leading edge and the trailing edge in a radial direction through a passage arranged in the inner or outer ring. The passage may be formed by cutting up an opening in the inner and/or outer ring.
The side face component may be locked from radial dislocation by stop shoulders arranged at one of the inner or outer ring and by a locking member arranged at the other of the inner and outer ring. It is furthermore possible to attach the side face component to the leading and trailing edges by welding. Since the connection between the side face component and the leading and trailing edges run in the radial direction access is easier in comparison to forming a weld along the axial direction where the side face component abuts to the inner and outer ring.
The invention also relates to a gas turbine engine component comprising an inner ring, an outer ring and at least one strut connecting the inner ring with the outer ring. The strut includes a load carrying edge and a side face component. The load carrying edge has an attachment face, which is facing in an inward direction of the gas turbine engine component. With inwardly is here intended that the attachment face is directed in a direction from an inlet or outlet of the gas turbine engine component which is closest to the load carrying edge. The side face component includes side faces and an end face. The end face is positioned in abutment with the attachment face. In an embodiment the struts are formed by a set of leading and trailing edges of the set of struts, and a set of side face components, where each side face component is connecting a leading and a trailing edge in the set of leading and trailing edges. The side face components are forming side faces of the struts. Each leading edge has a rear attachment face and each trailing edge has a front attachment face, the rear and front attachment faces defining a space receiving the side face component. When the struts are formed by load carrying leading and trailing edges secured to the inner and outer rings and since a side face component may be received in a space defined between the leading and trailing edges. Hence, ample room to allow easy access to secure the leading and trailing edges to the inner and outer rings is provided.
Locking means may be arranged to retain the side face components in the spaces after the side face components are pushed into the spaces.
The inner and/or outer ring may include a set of passages allowing introduction of the side face components into the spaces arranged to receive the side face components.
Further advantageous embodiments and further advantages to the invention emerge from the detailed description below and the claims.
The invention will be explained in further detail below, with reference to embodiments shown on the appended drawings, wherein
a illustrates different embodiments of the leading and trailing edges,
b illustrates an integrated gas turbine component,
a illustrates a cross sectional side view of a schematic construction of an upper part of outer ring, taken at the location A-A indicated in
a illustrates a cross sectional side view of a schematic construction of an upper part of an inner ring, taken at the location B-B indicated in
a illustrates aside view of the gas turbine engine component, taken at the location C-C indicated in
The invention will below be described for a turbofan gas turbine aircraft engine 1, which in
A high pressure shaft joins the high pressure turbine 13 to the high pressure compressor 11 to form a high pressure rotor. A low pressure shaft joins the low pressure turbine 14 to the low pressure compressor 10 to form a low pressure rotor. The high pressure compressor 11, combustor 12 and high pressure turbine 13 are collectively referred to as a core engine. The low pressure shaft is at least in part rotatably disposed co-axially with and radially inwardly of the high pressure rotor. A load carrying, torsionally rigid engine structure 15, in the following referred to as a static component, is arranged between the low pressure compressor 10 and the high pressure compressor 11 in the axial direction of the engine 1. The load carrying static component is also known as a case, housing or frame. The load carrying, torsionally rigid engine structure 15 is highly loaded during certain periods of a normal operating cycle of the engine.
The engine 1 is mounted to the aircraft (not shown) at a forwardly located fan frame forward mount 24 on the static component 15 and at a rearwardly located turbine frame aft mount 25 on the turbine frame. A mount system 26, normally comprising a pylon extending downwards from an aircraft wing and associated thrust links, is schematically indicated in
The annular intermediate member 16 is supported between an inner annular support member 19 and an outer annular support member 20 by a plurality of circumferentially spaced radial inner and outer struts 21, 22, or stator struts. The inner and outer support members 19, 20 and the annular intermediate member 16 are coannular. Opposite ends of the inner struts 21 are rigidly connected to the inner annular member 19 and the intermediate member 16 for transmitting structural loads between the members. Opposite ends of the outer struts 22 are rigidly connected to the intermediate member 16 and the outer annular member 20 for transmitting structural loads between the members. The air is forced rearwardly through openings between adjacent struts 21, 22. The annular intermediate member 16 comprises an inner ring 27 and an outer ring 28 of metal material. The outer ring 28 together with the outer annular member 20 defines the outer passage 18. The inner ring 27 together with the inner support member 19 defines the inner passage 17.
The method for fabricating a gas turbine engine component can for example be applied when securing the intermediate member 16 to the outer support member 20 or when securing the inner support member 19 to the intermediate member 16. The invention is particularly useful in locations where the space between an inner ring and an outer ring is limited. The space between the inner ring 19 and the outer ring 27 defining the core channel at the static component 15 is very limited. The invention may be used for further gas turbine engine components where an inner ring is attached to an outer ring via a set of struts.
In
The inner and outer rings are connected by a set of struts, of which one complete strut 34 is shown in the upper part of the figure. The struts are evenly distributed along the circumphery of the gas turbine engine component. The strut 34 includes a leading edge 44 and a trailing edge 46. The leading edge and trailing edge are formed as load carrying pillars connecting the inner and outer ring 30, 32. The leading and trailing edges may be of solid metal, preferably of a string pressed titanium or titanium alloys. The leading and trailing edges are secured to stubs 48a-48d, formed on the inner and outer rings to form a base for attachment of the leading and trailing edges.
The leading edge 44 has a rear face 50 and the trailing edge 46 has a front face 52, the rear and front face 50, 52 defining a space 54. A side face component 56 is received in the space 54. The side face component 56 may be a sheet metal structure. In the upper part of the figure the side face component 56 has been introduced into the space 54 between the leading and trailing edges, while in the lower part the side face component has not yet been introduced. The space 54 between the leading and trailing edges is therefore clearly visible. The side face component may be introduced via openings present in the inner and/or outer ring.
The side face component may be welded to the leading and trailing edges along first, essentially radial interface 51 between the side face component and the load carrying edges. However a second, essentially axial interface 53 between the side face component and the inner and outer ring, is essentially free from a welding seam, unless the part is made accessible form an opening 58 (
Different embodiments of the side face component 56 are described further below with reference to
In
The construction of the leading and trailing edges may be formed in any arbitrary manner. It is however essential that the side face component is secured in abutment to the load carrying leading and/or trailing edges after the inner and outer rings have been secured to each other by the leading and/or trailing edge. Advantageously the strut includes a leading as well as a trailing load carrying edge. However, It may be possible to use only a leading or only a trailing load carrying edge. The extension of the load carrying edges in an-axial direction of the component is less than ⅓ of the total extension of the strut in the axial direction. However, When both a leading and a trailing load carrying edge are used, the space between the load carrying leading edge and the load carrying trailing edge is at least AA of the total extension of the strut in the flow direction.
In
a illustrates a cross sectional side view of a schematic construction of an upper part of the outer ring, taken at the location A-A indicated in
In
a illustrates a cross sectional side view of a schematic construction of an upper part of an inner ring, taken at the location B-B indicated in
In
a illustrates a side view of an upper part of a schematic construction of a gas turbine engine component, taken at the location C-C indicated in
In
In
In
In
The second end face 72b includes one or two two end portions 72c, 72d. The one or two end portions being connected to one of said first and second side faces 70a, 70b. The end portions or portions being adapted to bear against an inner surface of the other of said leading or trailing edge 44, 46. In
The step of attaching said inner ring to said outer ring via a load carrying edge of a strut may include attachment of said inner to said outer ring via a load carrying leading edge and a load carrying trailing edge. The load carrying leading edge and load carrying trailing edge are positioned at a distance relative to each other so as to leave a space in between them. The step of attaching a side face component of a strut in abutment with said load carrying edge may includes attachment of the side face component of a strut in said space and in abutment with both said load carrying leading edge and said load carrying trailing edge.
The side face component may suitably be introduced via an opening in the inner and/or outer ring. In a fifth method step S50 the side face component is secured to the gas turbine engine component. The side face component may be secured by fixing the side face component to the leading and/or trailing edges. Alternatively or additionally the side face component may be attached to the inner and/or outer ring. The side face component may be secured by welding, by a locking device or by expanding the side face component when the side face component is located in the space between the leading and trailing edges.
The invention is not limited to the embodiment described above, but can be freely varied within the scope of the claims. For example, the engine component shown in
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/SE2009/000209 | 4/23/2009 | WO | 00 | 1/25/2012 |