FR3059047A1 - COMBUSTION CHAMBER INJECTOR FOR TURBOMACHINE AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Abstract

Combustion chamber injector (1 ') for a turbomachine, in particular an aircraft, comprising a body (11') comprising at least one fuel injection circuit (C1 ') which comprises an internal duct (12a') of which a downstream end opens out (12aa ') at a first end of the body and is connected to at least one fuel ejection port (50'), and an upstream end (12ab ') opens at a second end of the body and is connected a nozzle (8 '), said nozzle defining a calibrating restriction of passage section in said conduit, characterized in that said nozzle is formed integrally with said body.

Description

(57) injector (1 ') of combustion chamber for a turbomachine, in particular of an aircraft, comprising a body (11') comprising at least one fuel injection circuit (C 1 ') which comprises an internal duct ( 12a ') of which a downstream end opens (12aa') at a first end of the body and is connected to at least one orifice (50 ') of fuel ejection, and an upstream end (12ab') opens at a second end of the body and is connected to a nozzle (8 '), said nozzle defining a calibrating restriction of passage section in said conduit, characterized in that said nozzle is formed in one piece with said body.

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Combustion chamber injector for a turbomachine and its manufacturing process

TECHNICAL AREA

The present invention relates to a combustion chamber injector for a turbomachine, in particular for an aircraft, and its manufacturing method.

STATE OF THE ART

The state of the art includes in particular documents FR-A1-2 971 039 and FR-A1-3 013 805.

A mixture of compressed air and a suitable fuel is generally injected into a combustion chamber of a turbomachine using a plurality of injectors. The injectors are mounted in the wall of a flame tube arranged, preferably, at the bottom of the chamber. This makes it possible to distribute the mixtures coming from the different injectors evenly.

In each injector, a nozzle introduces fuel at the end of a pipe. The air comes from the top stage of a compressor of the turbomachine and is introduced into the injector in an annular manner. The air and fuel are generally introduced into vortices with counter-rotating channels or spins, then the fuel particles are sprayed into the air via a mixer (in some cases, but not exclusive). The mixture, ignited using a candle located at a determined distance, is burned in the chamber. The gases generated then have a high kinetic energy, which is used to generate propulsion or mechanical energy.

In the current technique, fuel injectors are complex and expensive to produce. This is in particular due to the fact that they are made up of an assembly of several parts (injector body, nozzle, seal, screw cap, threaded insert, etc.). The nozzle, for example, is an insert in the body of the injector, which should be held in place by tightening by means of the screw cap. Optimal tightening is difficult to master, which leads to significant production costs.

The invention proposes an improvement to this technology, which is simple, effective and economical.

STATEMENT OF THE INVENTION

To this end, the invention provides a combustion chamber injector for a turbomachine, in particular for an aircraft, comprising a body comprising at least one fuel injection circuit which comprises an internal duct, one downstream end of which opens at a first end. of the body and is connected to at least one fuel ejection orifice, and an upstream end opens out to a second end of the body and is connected to a nozzle, said nozzle defining a calibrating restriction of passage section in said conduit, characterized in that said nozzle is formed in one piece with said body.

The invention makes it possible to simplify the injector by means of a nozzle integrated into the body of the injector. The invention thus makes it possible to simplify the design, the manufacturing cost and the functional robustness of the injector.

In one embodiment of the invention, said nozzle is formed by a protruding element inside said conduit.

The present invention also relates to a turbomachine, in particular for an aircraft, comprising at least one injector as described above.

The present invention also relates to a method of manufacturing an injector as described above, in which it comprises a step of producing a single piece of said body with said nozzle.

Advantageously, the body is made in one piece by laser fusion on powder beds, by foundry or MIM (Metal Injection Molding) process.

The nozzle comprises a calibrated orifice for the passage of fuel, which can be obtained directly during the production of said body. As a variant, the calibrated fuel passage orifice is obtained by machining, preferably EDM, after the said body has been produced.

DESCRIPTION OF THE FIGURES

The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of non-limiting example and with reference to the appended drawings, in which:

FIGS. 1a and 1b are respectively exploded and sectional views of a fuel injector according to the prior art,

FIGS. 2 and 3 are schematic sectional views of fuel injectors according to the invention,

- Figure 4 is a very schematic view of a machine for producing an injector according to the invention, by additive manufacturing.

DETAILED DESCRIPTION

With reference to the exploded view and the sectional view of the respective figures 1a and 1b, an injector 1 of the prior art, as described in application FR-A1-2 971 039, comprises a fixing flange 10 on a casing 2 of the annular combustion chamber 3, a body 11 of longitudinal axis X'X of the injector reference, and a circular swirl 4 of central wall 14 and of axis of symmetry ΥΎ inclined with respect to the axis X ' X. This central wall 14 makes it possible to project, through the opening 15 of a sheath 5, an air / fuel mixture into a flame tube 6 which bears on the sheath 5. The swirl 4 is dimensioned so that the fins 40 of this whirlpool, regularly distributed around the periphery of the central wall 14, bear in a self-adjusting and self-centered manner on the edge of the opening 15.

The injector 1 here comprises a double fuel injection circuit which consists of a starting fuel circuit C1, capable of triggering the ignition of the chamber 3 and of operating in all flight regimes, and of a main fuel system C2, capable of operating in all flight regimes following start-up.

The C1 and C2 circuits are coupled to fuel supply pipes (not shown). These circuits consist of access bores 2a, 2b formed in the fixing flange 10, in connection with parallel longitudinal conduits, respectively 12a and 12b, extending in the body 11 bearing on sealing sockets 13a and 13b housed in this tube. These conduits extend in the body 11 parallel to the longitudinal axis X’X and open into the combustion chamber 3 through the central wall 14.

Regarding the starting circuit C1, the conduit 12a opens at one end 12e - substantially at the center of a hemispherical portion 11s in extension of the body 11. In addition, at this end, the conduit 12a accommodates - in a cylindrical recess 21 of inclined axis coincident with the axis ΥΎ of the vortex 4 - a helical fuel rail 7. The recess 21 has a conical end 21c coupled, through the central wall 14 of the vortex 4, to a central channel 41 of axis coincident with the axis Y Ύ of the vortex 4 or of the recess 21. This central channel 41 opens into the combustion chamber 3 to form a fuel ejection orifice.

Regarding the main circuit C2, a nozzle 8 is mounted in the access bore 2b of the flange 10. This nozzle is used to calibrate the fuel flow which varies according to the flight phases. After a bend 12c, the longitudinal duct 12b is oriented in a final portion 12f parallel to the axis ΥΎ and opens into an annular channel 16 produced in the hemispherical portion 11s. This annular channel 16 has two ends 16e. In other words, this channel is not closed in on itself. Thus, no "dead" area where fuel could stagnate forms.

The annular channel 16 is brazed to the central wall using a solder 20 which reveals the non-looped shape of the annular channel

16. This annular channel 16 communicates with spray channels 42 arranged radially and distributed equidistantly around the central channel 41.

The radial channels 42 have an orientation along axes K’K symmetrically inclined with respect to the axis ΥΎ of the central channel 41 (FIG. 1b), and in counter-rotation with respect to the inclination of the fins 40 of the swirler 4.

The inlet air flow F _E - coming from the last compression stage - passes through openings 170 formed in a flared cover 17 extending the body 11, and is then guided in an air circuit C3 circulating in an inter-spherical space "E >>. This space "E" is formed between two portions of concentric spheres formed by the portion 11s and partially by the sleeve 5 in a spherical portion 5s enveloping the portion 11s of the injector body. The sheath has a cylindrical part with circular section 5c, which makes it possible to provide support for the flame tube 6 and for the flared cover 17 of the tube 11.

The central starting circuit C1 is thermally protected from coking by the circulation of the fuel in the annular channel 16 of the main circuit C2, this main circuit itself being thermally protected by the flow of peripheral air F circulating in the interspherical space "E >> of the air circuit C3.

At the outlet of injector 1, the air flow Fs forms, passing between the fins 40, an air cone Ca enveloping the fuel outlet cone Cs of the main circuit C2.

As can be seen in Figures 1a and 1b, the injector 1 has a large number of parts, which makes it expensive and also complex to produce.

FIGS. 2 and 3 show exemplary embodiments of the invention, in which the body 11 'of the injector 1' comprises at least one fuel injection circuit C1 which comprises an internal conduit 12a 'including a downstream end 12aa 'opens at a first end of the body and is connected to at least one orifice 50' of fuel ejection, and an upstream end 12ab 'opens at a second end of the body and is connected to a nozzle 8'. The terms upstream and downstream refer to the direction of flow of the fuel in the duct 12a ’. Conventionally, the nozzle 8 ′ defines a calibrating restriction of passage section in the conduit 12a ’.

According to the invention, the nozzle 8 ’is formed in one piece with the body 11’. In the example shown, the conduit 12a ’has a substantially cylindrical rectilinear portion and the nozzle 8’ is formed by a protruding element inside the conduit and close to the end 12ab ’.

In the example shown, the body 11 ’is also formed in one piece with an external annular fixing flange 10’.

It is thus understood that the nozzle 8 ’is integrated into the body 11’ of the injector 1 ’. The manufacture of the injector therefore includes a step of producing a single piece of the body 11 ’with the nozzle 8’.

Advantageously, the body is made in one piece by laser fusion on powder beds, by foundry or MIM process (metal injection molding).

FIG. 4 shows a machine for manufacturing an injector by additive manufacturing and in particular by selective melting of layers of powder by high energy beam.

The machine comprises a supply container 170 containing metal powder, a roller 130 for transferring this powder from this container 170 and spreading a first layer 110 of this powder on a construction support 180 (it may be a solid support, a part of another room or a support grid used to facilitate the construction of certain rooms).

The machine also comprises a recycling bin 140 for recovering a tiny part of the used powder (in particular not melted or unsintered) and the major part of the excess powder, after spreading the powder layer on the construction support 180 Thus, most of the powder in the recycling bin is made up of new powder. Also, this recycling bin 140 is commonly called by the profession overflow bin or ashtray.

This machine also includes a generator 190 of laser beam 195, and a control system 150 capable of directing this beam 195 onto any region of the construction support 180 so as to sweep any region of a layer of powder. . The shaping of the laser beam and the variation of its diameter on the focal plane are done respectively by means of a beam dilator 152 and a focusing system 154, the assembly constituting the optical system.

This machine can apply the process similar to a direct metal deposition process or DMD (acronym for English Direct Métal Déposition) on a powder and can use any high energy beam in place of the laser beam 195, as long as this beam is sufficiently energetic to in the first case melt or in the other case to form necks or bridges between the powder particles and part of the material on which the particles rest.

The roller 130 can be replaced by another suitable depositing system, such as a reel (or hopper) associated with a scraper blade, a knife or a brush, capable of transferring and spreading the powder in a layer.

The piloting system 150 comprises for example at least one orientable mirror 155 on which the laser beam 195 is reflected before reaching a layer of powder, each point of the surface of which is always located at the same height relative to the lens. focusing, contained in the focusing system 154, the angular position of this mirror 155 being controlled by a galvanometric head so that the laser beam scans at least one region of the first layer of powder, and thus follows a pre-established part profile .

The machine works as follows. Using the roller 130, a first layer 110 of powder of a material is deposited on the construction support 180, this powder being transferred from a feed tank 170 during a forward movement of the roller 130, then it is scraped , and possibly slightly compacted, during one (or more) movement (s) of return of the roller 130. The excess powder is recovered in the recycling tank 140. A region of this first layer 110 of powder is carried , by scanning with the laser beam 195, at a temperature higher than the melting temperature of this powder (liquidus temperature). The galvanometric head is ordered according to the information contained in the database of the computer tool used for the computer-aided design and manufacture of the part to be manufactured. Thus, the powder particles 160 of this region of the first layer 110 are melted and form a first bead 115 in one piece, integral with the construction support 180. The support 180 is lowered by a height corresponding to the already defined thickness of the first layer (between 20 and 100 μm and in general from 30 to 50 μm). The thickness of the layer of powder to be merged or consolidated remains a variable value from one layer to another because it is highly dependent on the porosity of the powder bed and its flatness while the preprogrammed movement of the support 180 is an invariable value to the nearest game. A second layer 120 of powder is then deposited on the first layer 110 and on this first bead 115, then a region of the second layer 20 which is partially or completely above this first bead is heated by exposure to the laser beam 195 115, so that the powder particles of this region of the second layer 120 are melted, with at least part of the first element 15, and form a second integral or consolidated bead 125, all of these two cords 115 and 125 forming a block in one piece. To this end, the second bead 125 is advantageously already fully bonded as soon as part of this second bead 125 binds to the first element 115. This process of building the part is then continued layer by layer by adding additional layers of powder on the set already formed. The scanning with the beam 195 makes it possible to construct each layer by giving it a shape in accordance with the geometry of the part to be produced. The lower layers of the room cool more or less quickly as the upper layers of the room are built.

In order to reduce contamination of the part, for example dissolved oxygen, oxide (s) or another pollutant during its layer-by-layer manufacture as described above, this manufacture must be carried out in an enclosure at degree d '' hygrometry controlled and adapted to the process / material pair, filled with a neutral gas (non-reactive) vis-à-vis the material considered such as nitrogen (N2), argon (Ar) or helium (He ) with or without the addition of a small amount of hydrogen (H2) known for its reducing power. A mixture of at least two of these gases can also be considered. To prevent contamination, in particular by oxygen from the surrounding environment, it is customary to put this enclosure under overpressure.

Thus, according to the current state of the art, selective melting or selective sintering by laser makes it possible to build with good dimensional accuracy of lightly polluted parts whose geometry in three dimensions can be complex.

The selective melting or selective sintering by laser also preferably uses powders of spherical morphology, clean (that is to say not contaminated by residual elements originating from the synthesis), very fine (the dimension of each particle is between 1 and 100 pm and preferably between 45 and 90 pm), which makes it possible to obtain an excellent surface condition of the finished part. The powder is preferably made of a metal alloy, for example based on nickel.

Selective melting or selective sintering by laser also makes it possible to reduce manufacturing times, costs and fixed costs, compared to a part molded, injected or machined in the mass.

The nozzle 8 'can be produced, during additive manufacturing, directly with an orifice 8a' calibrated for fuel passage (Figures 2 and 3). As a variant, this calibrated orifice is obtained by machining, preferably EDM, after the production of said body.

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Claims (7)

1. Combustion chamber injector (T) for a turbomachine, in particular for an aircraft, comprising a body (11 ') comprising at least one fuel injection circuit (C1') which comprises an internal duct (12a ') of which a downstream end opens (12aa ') at a first end of the body and is connected to at least one orifice (50') of fuel ejection, and an upstream end (12ab ') opens at a second end of the body and is connected to a nozzle (8 '), said nozzle defining a calibrating restriction of passage section in said conduit, characterized in that said nozzle is formed in one piece with said body. 2. Injector (Γ) according to the preceding claim, wherein said nozzle is formed by a projecting element inside said conduit (12a ’). 3. Turbomachine, in particular of an aircraft, comprising at least one injector (T) according to one of the preceding claims. 4. Method for manufacturing an injector (1 ’) according to claim 1 or 2, in which it comprises the steps of: - realization of said body (11 ’) and said nozzle (8’) in one piece. 5. Method according to the preceding claim, wherein the body (1Γ) is made in one piece by laser fusion on powder beds, by foundry or MIM process. 6. Method according to claim 4 or 5, wherein the nozzle (8 ’) comprises a calibrated orifice (8a’) for the passage of fuel, which is obtained directly during the production of said body. 7. The method of claim 4 or 5, wherein the nozzle (8 ’) comprises a calibrated orifice (8a’) for the passage of fuel, which is obtained by machining, preferably EDM, after the production of said body. 1/2 ^Ίί> Fig. 1b