The present invention relates to the technical field of assemblies in the aeronautics sector, especially in turbomachine compressor rectifiers. In particular, the invention relates to a (stage of a) turbomachine compressor rectifier made up of parts of an organic matrix composite and made up of at least one blading subassembly incorporating a mechanical assembly achieved by sealing.
In the context of the present invention, “sealing” refers to the operation of fastening a part in a carrier by means of a polymer element, which may include filler or not, by mechanical locking and/or physicochemical interaction with the carrier and/or the part to be attached.
In the current art, there are no turbomachine compressor rectifiers made of composite material, but rather only made of a metal material, for example titanium (TA6V), steel or aluminum.
Furthermore, the blades generally have a single material and profile on a same stage, possibly with small variation in the calibration angle for aerodynamic reasons on the last stage.
Lastly, the current systems rest on an outer shroud, serving as a casing that performs most of the mechanical functions, on blades attached to a first end on those outer shrouds by various assembly technologies (welding, riveting, bolting), and on relatively flexible inner shrouds attached to the blades at a second end but that do not perform any structural function.
Today, one of the major problems of the use of composite parts lies in their interface with the outside. The invention proposes a solution for assembling parts of various natures: either “metal/composite” or even “composite/composite” hybrids, while using the smallest possible quantity of metal attachment means, the latter creating many issues (mass, differential expansion, etc.).
Document EP 1 493 901 discloses an assembly between blades and the inner shroud of a compressor rectifier of an aeronautic engine. Each blade passes through an opening formed in the inner shroud and is attached thereto using sealing cement containing an organic polymer adhesive.
Document EP 1 081 335 discloses a stator assembly for a rotary machine and, more specifically, the assembly of stator blades to inner shroud abradables. The stator assembly comprises a thermoplastic shoulder provided with an opening designed to receive the foot of the stator blade, and the elastomer abradable connected to the shoulder using adhesives.
Document DE 10 2009 010 613 discloses a method for producing a closed strip around the blades of a turbine. A strip of fibrous material is inserted into a housing arranged at the free end of the blades, and a matrix is infiltrated in the fibrous material of the strip and polymerized to form a composite.
Document FR 1 431 558 discloses a blade structure comprising a case and two concentric enclosures, an outer enclosure and an inner closure, the latter being offset from the outer enclosure by separating means. The blades are mounted gripped in holes formed facing each other in both enclosures. The blades may be welded, glued or fastened on the outer enclosure, which is mounted gripped in an outer case. In particular, all these parts of the blade structure may be made of synthetic resin and glued to one another. The blades may also be made of metal and welded on the outer case.
The present invention aims to overcome the drawbacks of the state of the art.
In particular, the invention aims to allow the production of bladed rectifiers with a light weight and at a low cost for all compressors whose rotor is made up of discs, of a drum, or of other elements.
The invention also aims to allow the easy assembly of rectifier blades with varied properties, so as to best optimize the mechanical strength as well as the costs.
The invention also aims to allow the rectifier to be easily assembled and disassembled, thereby favoring the in-use maintenance aspects while limiting the number of metal fastening elements.
The invention also aims to save time during the assembly of the compressor.
The invention lastly aims to allow permanent and non-deformable connection of the metal or OMC (organic matrix composite) composite parts to parts made of OMC composite.
A first object of the present invention most generally relates to a mechanical assembly in the aeronautics field comprising:
According to specific embodiments of the invention, the mechanical assembly comprises at least one or a suitable combination of the following features:
A second object of the present invention relates to a rectifier stage for a turbomachine compressor comprising a mechanical assembly of a plurality of blades to a housing with an OMC wall imparting structural rigidity to the assembly, according to the above principle, the blades each comprising a foot, said recess with an OMC wall and said sealing composite cooperating to seal the feet of the blades in the recess.
According to specific embodiments of the invention, the rectifier stage comprises at least one or a suitable combination of the following features:
A third object of the invention relates to a turbomachine compressor comprising one or more rectifier stages as described above.
The assembly as in a preferred embodiment of the present invention, whose principle and parts are shown in a perspective view in
According to the present invention, the composite carrier with heat-sealable or thermoplastic matrix 2 may be manufactured by any type of method allowing to obtain sufficient mechanical properties, such as for example: compression molding, injection of a thermoplastic or heat-sealable matrix, for example RTM (resin transfer molding), thermoforming or co-consolidation, etc. However, the invention is not limited to the use of a profiled part 2, for example in the shape of a “U”. Thus, a planar carrier may also be considered.
The sealing fastening composite or sealing composite or sealing material 4 has a base of a heat-sealable or thermoplastic matrix with between 0 and 70% of fibers, for example or preferably short fibers, and may be implemented by a method for injecting a thermoplastic or heat-sealable matrix or by compression molding. More generally, the filler may be any suitable mineral or organic filler. Thus, the matrix may nevertheless have a filler (with fibers) or not have a filler (pure matrix, 0% fibers).
Still according to the invention, the particular geometry of the foot of the blade 3A ensures that it is positioned and maintained in the structure (
The sealing or assembly technique used as in a preferred embodiment of the invention for metal blades 3 is illustrated more particularly and very diagrammatically in
Thermoplastic resin with a short fiber filler 4 is injected to fill the hollow volume that remains once the foot of the blade 3A is positioned in the carrier structure 2.
Furthermore, in order to best satisfy the aerodynamic constraints, material is over-injected at the level of the areas that do not allow to obtain the geometry by thermoforming (not shown). Filling with the sealing material to produce the mechanical and/or physicochemical connection is for example achieved in a second step or, if possible, at the same time as the composite structural part is produced.
According to the present invention, the material of the U-shaped composite carrier 2 and the sealing material 4 are identical or chemically compatible (for example, thermoplastic materials of the same nature), so as to produce chemical attachment between them. The resulting “material” connection ultimately amounts in only producing a single homogenous part, which is an additional advantage in terms of mechanical strength of the assembly.
According to still another preferred embodiment of the invention, the subassembly 1 belonging to the rectifier stage is in the shape of a ring or of a sector fastened to an outer shroud or to a case by means of mechanical fasteners, such as lock bolts (not shown).
If differential expansion problems appear, for example between bladed sectors, intermediate parts, that may be deformable or not, may be inserted radially or circumferentially into the assembly.
The advantages of the concept as in the invention for producing turbomachine rectifiers are the following:
Number | Date | Country | Kind |
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10009660.1 | Sep 2010 | EP | regional |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2011/065445 | 9/7/2011 | WO | 00 | 4/18/2013 |