BE1027343B1 - HYBRID ROTOR WITH PLATFORM PIONEERS PENETRATING INTO THE DRUM - Google Patents

Abstract

The invention relates to a blade (132) as well as a rotor (112) for a turbomachine and in particular its design and manufacture. The rotor (112) comprises a drum (116) of composite material and at least one row of rotor blades (132), each blade (132) having an attachment platform (134). The drum (116) further comprises an internal annular groove (116.1) in which the fixing platforms (134) are arranged. In addition, each platform (134) comprises a body (134.1) and an array of pins (136) in allies of the body (134.1), the pins (136) being embedded in the drum (116).

Description

, Ç BE2019 / 5369 Description

HYBRID ROTOR WITH PENETRATING PLATFORM PIONEERS

IN THE DRUM Technical field The invention relates to the design of a turbomachine, in particular an airplane turbojet or an aircraft turboprop. The invention relates in particular to a compressor rotor, said to be hybrid because it is composed of several parts, including a drum made of composite material and preferably metallic blades. PRIOR ART Turbomachines with "hybrid" compressors are known, making it possible to lighten the turbomachines, and therefore in particular a reduction in the fuel consumption of the aircraft and ease of handling of the assemblies during assembly of the apparatus. These hybrid compressors generally include a rotor made of composite materials and rotor and stator blades, most often metallic. The technical difficulty of fixing the blades to the rotor then arises. Patent document FR 2 143 561 discloses a turbomachine comprising a drum made of composite materials. The blades are fixed to the drum by metal bars, the bars comprising recesses so as to lighten the structure of the rotor. This design of the blades remains complex and makes it difficult to change a single blade during a maintenance operation, for example. Indeed, all the blades of a row of blades are fixed together on their support, the support being attached to the drum. Other designs are known in which the drum comprises annular rows of orifices in which the rotor blades are fixed. It is generally the blade platforms which are received in the orifices and the maintenance of the platforms in the orifices is ensured by retention rings positioned radially inside the platforms, each

> BE2019 / 5369 ring surrounding a whole row of vanes or a half-row of vanes. Such a rotor remains heavy due to the presence of the rings. Summary of the Invention Technical Problem The object of the invention is to provide a rotor that is lighter and more economical to manufacture or assemble. Technical solution The subject of the invention is a blade for a turbomachine compressor, such as an aircraft turbojet, comprising a blade, a fixing platform capable of fixing the blade to a drum of the compressor and remarkable in that each platform comprises a body and a network of anchoring pins projecting from the body, the anchoring pins being intended to be embedded in the drum to fix the blade to the drum.

According to advantageous embodiments of the invention, the blade can include one or more of the following characteristics, taken in isolation or according to all the possible technical combinations: the orientations according to which the anchoring pins project from the body are heterogeneous. In other words, not all pawns have the same orientation. This helps promote the adhesion of the platforms to the drum against forces in all directions; the anchoring pins have a substantially spherical distal end, and / or a generally lanceolate and / or curled up shape and / or are in the form of claws; the blades comprise a respective blade, and the blade, the platform and the anchoring pins are in one piece.

The subject of the invention is also a rotor for a turbomachine compressor, such as an aircraft turbojet, comprising: a drum made of composite material; at least one row of rotor blades as defined above and remarkable in that the drum comprises an internal annular groove in which are arranged the fixing platforms of the rotor blades, the blade anchoring pins being embedded in the drum to ensure fixing the blade to the drum.

According to advantageous embodiments of the invention, the rotor can comprise one or more of the following characteristics, taken in isolation or according to all the possible technical combinations: the pins are molding inserts. The connection between the pions and the drum is therefore made at the level of the surface microporosities; the network of pions comprises pions which extend radially from the body, and / or pions which extend circumferentially from the body, and / or pions which extend axially from the body; - Each blade has a blade which passes through an orifice in the drum and extends radially outwards; - A network of pins is positioned on a lateral face of the vane fixing platform, so as to be inserted on a corresponding lateral face of the annular groove of the drum.

The invention also relates to a method of manufacturing a rotor as explained above, the method comprising the following steps: the production of blades, each blade comprising a blade, a fixing platform and an array of pawns, the blade, its blade, its platform and its network of pawns being at least in part obtained by foundry and / or by machining; placing the blades in a mold; the deposition of carbon fibers in contact with the blades on a radially outer face of the platforms and surrounding the blades; the placement of a resin covering the fibers; the solidification of the resin, the solidified resin and the carbon fibers forming a drum.

The invention also relates to a method of manufacturing a rotor as explained above, the method comprising the following steps: the production of blades, each blade comprising a blade, a fixing platform and an array of pawns, the blade, its blade, its platform and its network of pawns being at least in part obtained by foundry and / or by machining; making a malleable drum preform with an annular groove; the insertion of the pins in the annular groove of the preform by plastic deformation of the preform; solidification of the preform.

According to advantageous modes of the invention, the method can comprise one or more of the following characteristics, taken in isolation or according to all the possible technical combinations: - prior to solidification, the blades and the drum are positioned in a mold and a resin is applied in a contact zone between the pins and the drum, the resin solidifying and sealing the pins in the drum; - Prior to the solidification of the resin or of the preform, carbon fibers are deposited in contact with the blades or the preform, and the resin is deposited to cover the fibers; - The resin is injected into the mold in the vicinity of the pins; - the blades remain outside the mold.

The invention also relates to a blade for a turbojet compressor having a fixing platform, the platform comprising a body and a network of pins projecting from the body.

In general, the advantageous modes of each subject of the invention are also applicable to the other subjects of the invention.

Each object of the invention can be combined with other objects, and the objects of the invention can also be combined with the embodiments of the description, which in addition can be combined with one another, according to all the possible technical combinations, unless the contrary is true. is not explicitly mentioned.

Advantages The hybrid design of the rotor according to the invention allows substantial weight savings compared to a rotor with a metal drum.

Compared to a one-piece rotor, the manufacturing time is drastically reduced, as several elements can be manufactured in parallel before being assembled together.

The production of pins in the platform of the rotor blades makes it possible to hold the blades to the drum without requiring heavy mechanical means (flanges, fasteners, etc.) or less reliable means (gluing, weld beads, etc.). The use of pins of different shapes allows better fixing of the parts.

Brief Description of the Drawings Figure 1 shows an axial turbomachine;

Figure 2 shows a schematic sectional view of an upstream portion of an axial turbomachine of the prior art; FIG. 3 represents an isometric view of a rotor blade according to the invention; Figure 4 shows an isometric view of a rotor drum according to the invention;

Figure 5 shows a sectional view of a compressor according to the invention.

Figure 6 shows several variants of pion profiles.

FIGS. 7 to 10 represent one of the methods of manufacturing the rotor according to the invention.

Description of embodiments

In the description which follows, the terms “internal” (or “interior”) and “external” (or “exterior”) refer to a positioning relative to the axis of rotation of an axial turbomachine.

The axial direction corresponds to the direction along the axis of rotation of the compressor rotor of the turbomachine.

The radial direction is perpendicular to the axis of rotation.

Upstream and downstream refer to the main flow direction of the flow in the turbomachine.

The figures show the elements schematically, in particular without certain assembly or sealing elements.

FIG. 1 is a simplified representation of a turbomachine 2, or turbojet 2. The turbojet 2 comprises a first low compressor.

pressure 4, a second high-pressure compressor 6, a combustion chamber 8 and one or more turbines 10. In operation, the mechanical power of the turbine 10 transmitted to the rotor 12 sets the two compressors (4, 6) in motion. Each compressor (4, 6) comprises several rows of rotor vanes 12 associated with rows of stator vanes.

The rotation of the rotor 12 around its axis of rotation 14 thus makes it possible to generate an air flow and to gradually compress the latter up to the entrance of the combustion chamber 8. A blower 18 or fan 18 is coupled to the rotor. 12 and generates an air flow which is divided into a primary flow 20 and into a secondary flow 22 passing through an annular duct (partially shown) along the machine to then join the primary flow 20 at the outlet of turbine 10. The separation between the primary flow 20 and the secondary flow 22 is produced by a separating spout 24, located at the upstream end of the annular duct.

Figure 2 is a sectional view of a turbomachine compressor known from the prior art. Part of the fan 18 can be seen there as well as the spout 24 for separating the primary 20 and secondary 22 flows. The rotor 12 can comprise several rows of rotor blades 32. The compressor is, in this figure, a low-pressure compressor. 4.

The low-pressure compressor 4 comprises at least one casing 23. The casing 23 may have a generally axisymmetric shape. It can be made of composite materials. The casing 23 can comprise fixing flanges 25, for example annular fixing flanges 25 for fixing the separating nozzle 24 and / or for fixing to an intermediate fan casing 18 of the turbomachine.

Thanks to the composite materials, the casing 23 can measure between 3 mm and 5 mm in thickness for a diameter greater than 1 meter. The low-pressure compressor 4 further comprises at least one rectifier which contains an annular row of stator vanes 26. Each rectifier is associated with the fan 18 or with a row of rotor vanes 32 in order to rectify the air flow therefrom. . More particularly, the stator vanes 26 extend essentially radially from the housing 23. The stator vanes 26 each comprise a fixing platform 28, and, optionally, fixing pins 29, such as threaded rods. The casing 23 may comprise annular layers of abradable material 31. The stator vanes 26 extend radially inwardly from the casing towards an internal ferrule 30, the internal ferrule 30 being provided with a layer of abradable material 33 which interacts with the rotor. 12.

Parallel to the stator vanes 26 extend rows of rotor vanes 32. Each rotor vane 32 comprises a blade 38, which extends from a ring 34 of the drum 16. The drum 16 is of substantially axisymmetric shape.

Figure 3 shows a perspective view of a rotor blade according to the invention. Figures 3, 4, 5 repeat the numbering of the previous figures for identical or similar elements, the numbering being however incremented by

100.

A rotor blade 132 according to the invention comprises an attachment platform 134 with an array of anchor pins 136, and the blade 138 extending from the attachment platform 134. The array of anchor pins 136 forms protrusions which protrude from a body 134.1 of the fixing platform 134. The body 134.1 advantageously has a substantially parallelepipedal shape of constant radial thickness. According to the invention, the pins 136 are intended to be embedded in the drum of the rotor (116 in FIGS. 4 and 5) and are, preferably, molding inserts. The pins 136 may extend from a radially outer face 134.2 of the fixing platform 134, and / or from a lateral face 134.3 of said platform 134, respectively in a substantially radial direction and a substantially axial or circumferential direction. The network of pions (136) may have a regular structure, for example a grid of staggered pions, regularly spaced. Alternatively, the position and general orientation of each pawn may not follow any regular pattern. The blade 132 is in one piece, that is to say that the blade 138, the platform 134 and the pins 136 are made of a single block of material. For examples of the shapes that pawns can take, see Figure 6 discussed below. FIG. 4 shows a perspective view of the drum 116 of a rotor 112 according to the invention. FIG. 5 shows a sectional view of a compressor comprising the rotor 112 according to the invention. The two figures will be described together in the following paragraphs. The rotor 112 essentially comprises two elements: a drum 116, of substantially axisymmetric shape and made of composite material, and one or more rows of blades 132 such as that illustrated in FIG. 3. The drum 116 comprises at least one internal annular groove 116.1 ( in this example three) in which the fixing platforms 134 of the rotor blades are arranged

132. This groove 116.1 makes it possible to stiffen the drum and to ensure the continuity of the air guiding surface, at the root of the blades 132. The fixing platforms 134 can be circumferentially contiguous or have inter-platform play, gap which can optionally be filled with a silicone seal. The drum 116 comprises rows of orifices 116.2 which are crossed by the respective blade 138 of each blade 132.

Thus, the radially outer surface 134.2 of the platform 134 of each rotor blade 132 comes into contact with an inner surface 116.3 of the drum 116. The pins 136 may have several respective orientations. Thus, the pins 136 can be inserted into the drum at the level of the lateral 116.4 and internal 116.3 surfaces of the internal annular grooves 116.1 of the drum 116. By these means, the adhesion between the blades 132 and the drum 116 is ensured. In FIG. 5 are also visible the other elements of the compressor 104, namely the casing 123, its flange 125, the journals 129 for retaining the stator vanes 126 and the abradable layers 133. FIG. 6 illustrates various embodiments of the pawns 136. Pawns can be cylindrical or tetrahedral in shape. Alternatively, the pins 136 may have a substantially spherical, cubic or ovoidal distal end 136.1. The examples of Figures 6A to 6C show different types of pins with spherical or ovoid head. The body of the pin can be conical, cylindrical or arched, possibly reinforced at its junction with the body of the platform, as for example illustrated in FIG. 6B with a foot in the portion of a sphere. In another embodiment, illustrated in FIG. 6D, the pawns are lanceolate and / or curled up, and / or a claw shape. Each pawn structure ensures adhesion between the drum and the blades to certain degrees and has its own weight. A combination or a compromise can therefore be found between the weight added by each pin and its capacity to participate in maintaining the blade in the drum.

It is understood that the same platform can include different types of pawns such as those mentioned above.

An example is given in Figure GE, in which the claw-shaped pegs are positioned with different orientations to maximize the anchoring of the platform in the drum.

A ball-headed pin can be positioned in the center of the pin array.

The dotted curve represents the profile of the blade.

The invention also relates to methods of manufacturing a rotor as described above.

A first process is illustrated in Figures 7 to 10 which are described together in the following paragraphs.

Only one blade is shown, but the rotor can include several rows of blades.

A mold made of two half-molds 70, 72 is used.

The half-molds 70, 72 are of generally axisymmetric shape, optionally sectioned into angular sectors: the external half-mold 72 and possibly the internal half-mold 70 can extend only over 180 ° around the axis 14. The rotor 12 may include tabs (not shown) for assembling the two half-rotor thus obtained.

The manufacturing process can comprise the following steps: the manufacture of the blades 132 by casting and / or by machining.

The blade 138, the platform 134 and its network of pins 136 are preferably in one piece; - the positioning of the blades 132 on an internal half-mold 70 (FIG. 8); - the deposition of glass fibers or carbon 80 on the platform 134 as well as on other parts of the mold (Figure 9). The fibers 80 may be coated with an adhesive coating to hold them firmly to the outer surface of the platform 134 during manufacture; - the closing of the mold by the positioning of the half-mold 72 (FIG. 10); the injection of resin 82 into the mold 70, 72, for example via vents in the half-mold 72, not shown.

Alternatively, certain more viscous resins can be introduced before the mold is closed; the solidification of the resin 82, for example by crosslinking;

- the opening of the mold.

Thus, the resin 82 and / or the fibers 80 penetrate into the inter-pion spaces.

The pins 136 therefore form molding inserts.

As illustrated in FIG. 10, the vanes 24 remain outside the mold 70, 72. This avoids the use of an unnecessarily large mold and makes it possible to guard against any alteration in the geometry of the blade, including the geometry. is already finished at this time of manufacture.

The invention also relates to a second process for obtaining the rotor, not shown, and in which a drum preform, which is still malleable, is produced.

The term "malleable" is understood to mean a preform which is solid but which can be plastically deformed.

The blade and its pins are manufactured then the pins are inserted into the malleable preform by plastic deformation of the preform (indentation). Thus, the vanes 132 are inserted radially from the inside into the drum 116, the radially outer face 134.2 of each platform 134 coming into contact with a lower face 116.3 of the inner annular reinforcement 116.1 of the drum 116. In this method, a resin can be used. be brought to the interface between the pins and the preform, to seal, by solidifying, the pins in the preform.

A mold similar to that of the process illustrated in Figures 7-10 can be used.

The resin can thus be injected under pressure once the preform and the blade have been positioned in a mold.

Generally speaking, carbon fibers are made with an elastomeric matrix or an organic matrix.

The manufacturing process used is visible on the finished part, at the interface between the pins and the drum.

Indeed, the resin of the drum penetrates into the surface microporosities of the pions.

Also, the undercut shape of the pins and the fact that the head of the pins is embedded in the drum reflect the manufacturing process used.

Claims (16)

Claims 1. A blade (132) for a compressor (104, 106) of a turbomachine (102), such as an aircraft turbojet (102), comprising: - a blade (138); - a fixing platform (134) capable of fixing the blade (132) to a drum of the compressor (116); characterized in that each platform (134) comprises a body (134.1) and an array of anchoring pins (136) projecting from the body (134.1), the anchoring pins (136) being intended to be embedded in the drum (116) to secure the vane (132) to the drum (116). 2. Blade (132) according to claim 1, characterized in that the orientations in which the anchoring pins (136) project from the body (134.1) are heterogeneous. 3. Blade (132) according to one of the preceding claims, characterized in that the anchoring pins (136) have a distal end (136.1) substantially spherical. 4. Blade (132) according to one of claims 1 or 2, characterized in that the anchoring pins (136) have a generally lanceolate and / or curled shape and / or are claw-shaped. 5. Blade (132) according to one of the preceding claims, characterized in that the blade (138), the platform (134) and the anchoring pins (136) are in one piece. 6. Rotor (112) for a compressor (104, 106) of a turbomachine (102), such as an aircraft turbojet (102), comprising: - a drum (116) made of composite material; - at least one row of blades according to one of the preceding claims; characterized in that the drum (116) comprises an internal annular groove (116.1) in which the fixing platforms (134) of the rotor blades (132) are arranged, the anchoring pins (136) of the blades (132) being embedded in the drum (116) to secure the blade (132) to the drum (116). 7. Rotor (112) according to claim 6, characterized in that the pins (136) are molding inserts. 8. Rotor (112) according to one of claims 6 or 7, characterized in that the network of pins (136) comprises pins (136) which extend radially from the body (134.1). 9. Rotor (112) according to one of claims 6 to 8, characterized in that the network of pins (136) comprises pins (136) which extend circumferentially or axially from the body (134.1). 10. Rotor (112) according to one of claims 6 to 9, characterized in that an array of pins (136) is positioned on a lateral face (134.3) of the fixing platform (134) of the blade ( 132), so as to fit on a corresponding side face (116.4) of the internal annular groove (116.1) of the drum (116). 11. Rotor (112) according to one of claims 6 to 10, characterized in that the blade (138) of each blade passes through a respective orifice (116.2) of the drum (116) and extends radially outwards. 12. A method of manufacturing a rotor (112) according to one of claims 6 to 11, the method comprising the following steps: - the production of blades (132), each blade (132) comprising a blade (138) , a fixing platform (134) and an array of pins (136), the blade (132), its blade (138), its platform (134) and its array of pins (136) being at least partly obtained by foundry and / or by machining; - The positioning of the blades (132) in a mold; - the deposition of fibers in contact with the blades (132) on a radially outer face (134.2) of the platforms (134) and surrounding the blades (138); - the placement of a resin covering the fibers; - solidification of the resin, the solidified resin and the carbon fibers forming a drum (116). 13. A method of manufacturing a rotor (112) according to one of claims 6 to 11, the method comprising the following steps: - the production of blades (132), each blade (132) comprising a blade (138), a fixing platform (134) and an array of pins (136), the blade (132), its blade (138) , its platform (134) and its network of pins (136) being at least partly obtained by foundry and / or by machining; - the realization of a malleable drum preform (116) with an annular groove (116.1); - the insertion of the pins (136) in the annular groove (116.1) of the preform by plastic deformation of the preform; - solidification of the preform. 14. The method of claim 13, characterized in that prior to solidification, the vanes (132) and the drum (116) are positioned in a mold and a resin is applied in a contact zone between the pins (136) and the drum (116), and in that the resin solidifies and seals the pins (136) in the drum (116). 15. The method of claim 13 or 14, characterized in that prior to the solidification of the resin or the preform, carbon fibers are deposited in contact with the blades (132) or the preform, and the resin is deposited for cover the fibers. 16. The method of claim 12, 14 or 15, characterized in that the blades (138) remain outside the mold.