Composite annular casing of a compressor for a turbo machine

Abstract

The invention relates to a composite annular casing for a low-pressure compressor of a turbo machine, including a wall of generally circular form or in a circular arc; a mounting flange extending radially from one side of the wall, forming an edge together with the wall; a main fibrous reinforcement (38) extending in a continuous manner along the wall and the flange and forming an angled portion and rounded in the area of the edge; an auxiliary fibrous reinforcement (56) extending along the edge; and a matrix. The auxiliary reinforcement (56) comprises a core extending along the edge in such a way as to occupy the volume between the edge and the angled portion of the main reinforcement (38). The invention also relates to a turbo machine comprising a composite annular casing, as well as to a method of manufacturing a composite annular casing of a turbo machine.

Claims

1. A method of manufacturing a composite annular casing of a turbo machine including a wall having one of a substantially circular profile and a circular arc, a mounting flange extending radially from one side of the wall and forming together with the wall an edge, said method comprising: positioning an auxiliary reinforcement in a corner of a moulding surface of an injection mould, the corner forming the edge, the auxiliary reinforcement including a contact surface; positioning a main reinforcement against the moulding surface such that its form is adapted to that of the auxiliary reinforcement in an area of the corner, the main reinforcement being produced with a rounding structured to come into contact with the contact surface of the auxiliary reinforcement; closing of the injection mould such that the rounding of the main reinforcement is flattened by the auxiliary reinforcement, and the contact surface of the auxiliary reinforcement is curved inwards by the main reinforcement; injecting a resin into the injection mould and polymerization of the resin; and demoulding the composite annular casing.

2. The method according to claim 1, wherein in the course of closing of the injection mould, at least one of: the main reinforcement is compacted, and the main reinforcement and a core are compacted mutually.

Description

DRAWINGS

(1) FIG. 1 illustrates an axial turbo machine according to various embodiments of the invention.

(2) FIG. 2 is a drawing of a compressor of a turbo machine according to various embodiments of the invention.

(3) FIG. 3 is a diagram depicting the method of manufacturing a casing according to various embodiments of the invention.

(4) FIG. 4 illustrates in schematic form a main fibrous reinforcement of the casing according to various embodiments of the invention.

(5) FIG. 5 depicts a section through the main fibrous reinforcement of the casing according to various embodiments of the invention along the axis 5-5 marked in FIG. 4.

(6) FIG. 6 illustrates in schematic form an auxiliary fibrous reinforcement of the casing according to various embodiments of the invention.

(7) FIG. 7 illustrates the stage of the method of positioning the auxiliary fibrous reinforcement in the mould according to various embodiments of the invention.

(8) FIG. 8 illustrates the stage of the method of positioning the main fibrous reinforcement in the mould according to various embodiments of the invention.

(9) FIG. 9 illustrates an intermediate state of the method, in which the reinforcements are arranged in the mould according to various embodiments of the invention.

(10) FIG. 10 illustrates the stage of the method of closing the mould according to various embodiments of the invention.

(11) FIG. 11 illustrates the stage of the method of injection of a resin into the mould according to various embodiments of the invention.

(12) FIG. 12 illustrates the stage of the method of demoulding of the casing according to various embodiments of the invention.

(13) Corresponding reference numerals indicate corresponding parts throughout the several views of drawings.

DETAILED DESCRIPTION

(14) The following description is merely exemplary in nature and is in no way intended to limit the present teachings, application, or uses. Throughout this specification, like reference numerals will be used to refer to like elements.

(15) In the context of the following description, the expressions interior or internal and exterior or external relate to positioning in relation to the axis of rotation of an axial turbo machine.

(16) FIG. 1 illustrates an axial turbo machine in a simplified manner. The turbo machine in this particular case is a turbofan engine. The turbofan engine 2 comprises a first compression stage, referred to as the low-pressure compressor 4, a second compression stage, referred to as the high-pressure compressor 6, a combustion chamber 8 and one or a plurality of turbine stages 10. In operation, the mechanical power of the turbine 10 transmitted via the central shaft as far as the rotor 12 sets the two compressors 4 and 6 in motion. A gear reduction mechanism can be used to increase the speed of rotation transmitted to the compressors 4 and 6. Or, each of the different turbine stages 10 can be connected to the compressor stages 4 and 6 via concentric shafts. These latter include several rows of rotor blades associated with rows of stationary blades. The rotation of the rotor 12 about its axis of rotation 14 thus makes it possible to produce an air flow and to compress the latter progressively as far as the entrance to the combustion chamber 8.

(17) An inlet blower commonly referred to as a fan 16 is coupled to the rotor 12 and generates a flow of air which is divided into a primary flow 18 passing through the various stages referred to above of the turbo machine, and a secondary flow 20 passing through an annular conduit (partially illustrated) along the machine before rejoining the primary flow as it exits from the turbine. The primary flow 18 and the secondary flow 20 are annular flows, and they are channelled through the casing of the turbo machine.

(18) FIG. 2 is a cross-sectional view of a compressor of an axial turbo machine 2 such as that depicted in FIG. 1. The compressor can be a low-pressure compressor 4. The presence of a part of the fan 16 and the separation nose 22 for the primary flow 18 and the secondary flow 20 can be noted there. The rotor 12 comprises a plurality of rows of rotor blades 24, being three in number in this particular case.

(19) The compressor comprises a plurality of rectifiers, being four in number in this particular case, each of which contains a row of stationary blades 26. The rectifiers are each associated with a row of rotor blades 24 in order to rectify the flow of air, in such a way as to convert the flow velocity under pressure.

(20) The compressor comprises at least one casing 28. The casing 28 can have a generally annular form with a revolution profile about the axis of rotation 14 of the turbo machine. This can be an external casing, and it can be produced from composite materials. It can be essentially flat. The annular casing 28 can comprise mounting flanges 30, for example annular mounting flanges, for the mounting of the separation nose 22 and/or for its attachment to an intermediate blower casing 32 of the turbo machine. The annular mounting flanges 30 can comprise mounting orifices (not illustrated) in order to permit mounting by means of bolts, or by means of lock bolts.

(21) The composite annular casing 28 can comprise a wall 34 that is generally circular or in a circular arc, of which the sides can be delimited by the flanges 30. The wall 34 can have the form of an arch, with a variation in radius along the axis 14. This evolution of the radius can be reversed. The wall 34 has an interior surface with a double curvature, one of the curvatures being in an axial plane, and the other curvature being in a radial plane. It is understood that the radial plane is perpendicular to the axis 14, the axial plane extending axially and radially.

(22) The wall 34 can have annular mounting surfaces for blades and/or series of mounting orifices (not illustrated) arranged in annular rows for the mounting of the stationary blades 26. The mounting orifices can be equipped with inserts (not illustrated) to reinforce the composite material of the annular casing 28. The inserts can be integrated into the thickness of the wall 34 or the mounting flanges 30.

(23) The annular casing 28 can also be a support for annular layers of an abradable material 36 which are arranged against the wall 34 and which are intended to ensure sealing with the external extremities of the rotor blades 24. The annular mounting surfaces of blades and the layers of abradable material 36 can form a sandwich structure. The annular casing 28 can comprise a metallic material and/or a composite material, for example with an organic matrix and carbon fibers. The annular casing 28 can comprise a main fibrous reinforcement and an auxiliary fibrous reinforcement.

(24) FIG. 3 illustrates a diagram of the method of manufacturing the composite annular casing 28.

(25) The method can comprise the succession, exemplarily in this order, of the following stages: (a) a first stage of positioning the auxiliary fibrous reinforcement (107); (b) a second stage of positioning the main fibrous reinforcement (108); (c) a third stage of closing the injection mould (110); (d) a fourth stage of injection and polymerization (111); and (e) a fifth stage of demoulding and, if required, machining (112).

(26) The first stage 107 can comprise a stage for the supply or implementation of an auxiliary fibrous reinforcement. It can be performed several times in such a way as to provide an auxiliary reinforcement in each inset edge or corner of the mould. Where appropriate, it can involve positioning an auxiliary reinforcement forming a loop bordering the contour of the annular portion. For example, the auxiliary reinforcement can border two axial flanges and two annular flanges.

(27) The second stage 108 can comprise a stage for the supply or implementation of a main fibrous reinforcement. In various alternative embodiments of the invention, the reinforcements can be implemented ahead of the first stage of the method. The main reinforcement can be implemented as part of the mould by stacking fibrous folds or by stacking fibrous folds on an external preforming support. Each fold can be woven in such a way as to possess in advance the form that it will occupy when it is arranged in the mould. The folds can be maintained one against the other by sewing them, or by gluing them in place.

(28) The stages presented above as well as the components that are used are described in more detail in the following paragraphs.

(29) FIG. 4 illustrates a section through the main fibrous reinforcement 38 of a casing, e.g., casing 28. The present approach is capable of being applied to any casing of the turbo machine 2.

(30) The main fibrous reinforcement 38 can possess symmetry of revolution with a revolution profile in relation to the axis 14. It can be flat. It can comprise a fibrous preform 40, which has been formed in such a way as to outline the form of the composite annular casing 28. The preform 40 can have a partition that is circular 42, or in a circular arc, intended to reinforce the wall of the annular casing 28, and at least one, and in various embodiments two, annular mounting flanges 44 which extend radially and which are intended to reinforce the annular flanges of the annular casing 28.

(31) The preform 40 can comprise a stack or a wrapping of different fibrous sheets 46 or fibrous folds 46, which can extend over the partition 42, and over at least one or a plurality of mounting flanges 44. Each fold 46 can extend over an axial fraction of the partition 42. The number of folds 46 can thus vary axially. The number of folds can increase in the downstream direction. At least one fold 46 can be added in order to reinforce the junction between the partition 42 and one of the flanges 44. The preform 40 can comprise a layer including a fibrous mat which, depending on its thickness, has a plurality of levels of fibers, for example at least two, in various embodiments at least four, and in other embodiments at least ten levels of fibers.

(32) The folds 46 can comprise carbon fibers, and/or graphite fibers, and/or glass fibers. Advantageously, the preform can comprise a plurality of types of folds. For example, the preform can comprise a central layer with folds made of carbon fibers, and at least one fold with glass fibers at the surface, if necessary in order to avoid galvanic corrosion.

(33) The folds 46 can be non-woven folds or woven folds, and the latter can comprise fibers and/or bundles of woven fibers in two directions, for example perpendicular. Each bundle of fibers can have a plurality of fibers depending on its cross section. Where appropriate, a fibrous fold can have three directions of weaving.

(34) The preform 40 can comprise at least five folds 46, in various embodiments at least twelve folds 46, and in other embodiments at least twenty folds 46 depending on its thickness. The folds 46 can form a sharp angle at the junction between the partition 42 of the radially exterior side of the preform 40. In the interior, beneath each annular flange 44, the preform 40 can form an annular rounding 50 or elbow, which results in the wrapping of the folds on the sharp angle.

(35) FIG. 5 illustrates a section of the main fibrous reinforcement 38 of the composite annular casing 28 along the axis 5-5 marked in FIG. 4.

(36) The annular casing 28 can describe a circle. It can be an annular case-half which describes a semi-circle, or an annular segment of an annular casing which describes a fraction of a circle; for example a quarter, a sixth, or an eighth of a circle.

(37) The annular casing 28 can be divided into one or a plurality of segments which extend in the axis of rotation 14. In order to join the case-halves or the casing segments together, these are equipped with axial mounting flanges 52 intended to be attached one to the other, and can form a smooth circle, in the absence of any step. Consequently, the partition and the wall can be semi-tubes and can extend over a semi-circle, or can be fractions of a circle. The assembly of case-halves or fractions of a casing permits a closed circle to be described.

(38) The main reinforcement 38 of the annular casing can also describe a semi-circle in such a way as to reinforce the case-half. The main reinforcement can have axial mounting flanges 52, which extend radially and which can exhibit a sinusoidal form. Since the main reinforcement 38 can be provided as a successive stack of fibrous folds 46, axial roundings 54 can appear at the side of the wall, at the axial junction with the axial flanges 52, along the entire length of the axial flanges 52.

(39) FIG. 6 illustrates a cross section through the auxiliary fibrous reinforcement 56 of the casing.

(40) The auxiliary fibrous reinforcement 56 can comprise a core 58. The core 58 can be a strand of fibers 60, where appropriate woven or braided three-dimensionally. The fibers 60 can describe spirals bordering the edge. The fibers 60 and/or the bundles of fibers of the core 58 can be of the same nature as the fibers of the preform 40. The expression of the same nature can be understood to denote the same material, and/or the same length and/or the same diameter.

(41) The auxiliary reinforcement 56 can comprise portions extending radially or axially beyond the core 58. The core 58 can have a prolongation and a transverse section in a plane perpendicular to its prolongation. Its transverse section can be generally a polygon, such as a triangle, being right-angled and/or isosceles as appropriate. The maximum height H of the triangle of the profile of the core 58 is substantially equal to the thickness of one of the flanges and/or the thickness of the wall of the first preform 40. The height is measured radially when the auxiliary reinforcement 56 is arranged in the mould, and it can be between 60% and 140%, and in various embodiments between 90% and 110%, of the thickness of one of the flanges and/or the thickness of the wall of the first preform. The core 58 has an essentially constant fiber density.

(42) The fibers 60 of the core 58 can be oriented in principle parallel to the prolongation of the auxiliary reinforcement 58. Each of their portions forms an angle of less than 45? in relation to the prolongation of the auxiliary reinforcement 56, and in various embodiments of less than 20?.

(43) FIG. 7 illustrates a first stage of the method of manufacturing the composite annular casing 28 according to various embodiments of the invention. A portion of the mould is illustrated in cross section in a plane passing through an axis which corresponds to the axis 14.

(44) The method utilizes an injection mould with a first mould 62. The first stage comprises the positioning of the auxiliary reinforcement 56 in the interior of the first mould 62, with its core against a moulding surface 64. The mould 62 can be a mould which makes it possible to produce an annular casing, a segment of the annular casing or a half shell. It can have moulding surfaces generated by a revolution profile. The mould 62 can have a generally tubular annular moulding surface 66 which is the conjugate of the interior surface of the annular casing. Although the tubular moulding surface 66 illustrated here is straight, it is obvious that, in practice, it can have any curved form making it possible to produce an axial flange or an annular flange.

(45) The mould 62 can also have a moulding surface extending radially 68, which is the conjugate of a mounting surface of one of the flanges. The tubular surface 66 and the radial surface 68 form a corner 70 or an inset angle 70 at their junction. In order to occupy this corner 70, the auxiliary reinforcement 56 is applied there.

(46) Although only a single auxiliary reinforcement 56 is illustrated, it is feasible to apply others, for example in the area of an opposite flange or in the area of step forms.

(47) FIG. 8 illustrates a second stage of the method of manufacturing the composite annular casing according to the invention.

(48) The second stage comprises the positioning of the main fibrous reinforcement 38, in such a way that the latter covers the tubular surface 66 and the radial surface 68 of the mould 62, as well as the auxiliary reinforcement 56, and any other auxiliary reinforcements. During this stage, the main reinforcement 38 enters into contact with the core 58 of the auxiliary reinforcement 56 in the area of a contact surface with a generally straight profile.

(49) FIG. 9 illustrates the main reinforcement 38 and the auxiliary reinforcement 56 when they are both in place in the mould 62.

(50) These reinforcements can adapt their form to the majority, in various embodiments to at least 80%, and other embodiments to the totality of the thickness of the flange 44 or 52 and/or to the majority, for example to at least 80%, and in various embodiments to the totality of the thickness of the partition 42 of the main reinforcement 38. In adapting their form, they are mutually compressed, the long side of the triangle curving inwards, and the rounding (50, 54) at the junction between the flange and the partition 42 of the main reinforcement being crushed, causing it to be flattened. The reinforcements can adapt their form to the majority, in various embodiments to the totality of the radial height of the core of the auxiliary reinforcement.

(51) At the interface 71 with the preforms, fibers of the two preforms can pass through the interface 71, and can be spaced on a same level. They can be interwoven, which improves the consistency in combination with the matrix.

(52) FIG. 10 illustrates a third stage of the method of manufacturing the composite annular casing according to the invention.

(53) The third stage of the method comprises the closing of the injection mould, the latter comprising at least a second mould 72 or backing mould 72 which is applied against the main reinforcement 38 and compacts it. The backing mould 72 can be a male mould. The backing mould 72 can reduce the thickness of the partition and/or the thickness of the flange (44, 52) of the main reinforcement 38. The mould 62 and the backing mould 72 define between them a moulding cavity essentially reproducing the form of the annular casing 28. During this stage, the core 58 can be compacted once more. The effect of closing of the mould can permit the thickness of the preforms to be reduced by at least 5%, and in various embodiments by at least 20%.

(54) FIG. 11 illustrates a fourth stage of the method of manufacturing the composite annular casing according to the invention.

(55) The fourth stage comprises the injection of a resin 74, in particular an organic resin, into the injection mould. The resin 74 can be a thermoplastic resin such as epoxy, polyetherimide (PEI), polyether ether ketone (PEEK). The injection can involve impregnating the preforms, according to a method of the RTM type (English acronym for Resin Transfer Moulding). The method can comprise an injection of a charged resin. If necessary, the injection can be assisted by aspiration.

(56) Following the injection, the mould can be maintained for a period of at least one hour at a temperature above 50? C., and in various embodiments above 120? C. Following these stages, the resin is polymerised and hardens and is able to adhere to the reinforcements, thereby forming a solid body.

(57) FIG. 12 illustrates a fifth stage of the method of manufacturing the composite annular casing 28 according to the invention.

(58) The fifth stage comprises the demoulding of the composite annular casing 28. In a first stage, the counter mould 72 is withdrawn from the mould 62, and a demoulding force is then applied to the casing 28 in order to extract it from the mould.

(59) The casing 28 can be machined after moulding. It can be perforated in the area of the flanges 30 in order to produce mounting orifices, and/or in the area of the wall 34 in order to permit the assembly of blades. If necessary, the axial and/or annular flanges can be cut out in order to remove the heterogeneous extremities, which were added specifically to improve the quality of the finished flanges.

(60) Once it has been polymerized, the matrix connects the main reinforcement 38 and the auxiliary reinforcement 56. It has a continuity of material in the interface 71 between the reinforcements (38; 56), which permits them to be joined together. This configuration is conducive to the anchoring of the reinforcements. The core of the auxiliary reinforcement 56 comprises fibers which extend radially, for at least 10%, in various embodiments for at least all, and other embodiments for at least two times the thickness of the wall 34. These fibers improve the resistance under radial compression of the edge and permit the edge to form a block. These fibers can extend from an edge 76 of the casing 28 as far as the main reinforcement 38.

(61) The main fibrous reinforcement 38 extends in a continuous manner along the wall 38 and the flange 30 forming an angled and generally rounded portion in the area of the edge. The core 58 extends along the edge 76 in such a way as to occupy the volume between the edge and the angled portion of the main reinforcement 38. The interface 71 can have a generally curved and substantially flattened profile. The reinforcements (38 and 56) can be configured in such a way that the casing 28 has a continuity and a homogeneity of the fiber density in the junction 80 between the flange 30 and the wall 34 and/or along the surfaces of the junction 80. This homogeneity improves the mechanical strength and the endurance of the casing 28, which can be subjected to vibrations, and to chemical attack at a temperature above 170? C., during the operation of the turbo machine.

(62) The general radius of the rounded interface and/or the thickness of the wall is/are greater than 1%, in various embodiments greater than 2%, in other embodiments greater than 4%, and, where appropriate, greater than 6% of the radius of the sharp edge.

(63) The casing 28 has a sharp edge 76 forming a salient angle. This edge can be integrated into the turbo machine, without the need for additional machining. The edge 76 can be generally perpendicular, which permits a smooth junction to be produced when it is brought into alignment with a corresponding edge. The joining together of the two edges makes it possible to provide a surface for guiding a flow in the absence of any projection which could have an adverse effect on the smoothness of the flow. This joint is also able to form a mounting zone that is free from roughness, for example in order to be able to support a blade platform against it with a view to its positioning and its mounting.

(64) The description herein is merely exemplary in nature and, thus, variations that do not depart from the gist of that which is described are intended to be within the scope of the teachings. Such variations are not to be regarded as a departure from the spirit and scope of the teachings.