Fuel injector with a purge circuit for an aircraft turbine engine

Abstract

Fuel injector (110) for an aircraft turbine engine, comprising a tubular body (112) having an axis of elongation (A) and comprising a first longitudinal end (114) for supplying with fuel and a second longitudinal end (116) for ejecting a jet of fuel, said body further comprising an integrated purge-air circuit which comprises an internal cavity (122) which is connected to air inlet orifices (124) situated on the body and to at least one air outlet situated at said second end, characterized in that air-flow disruptors (150, 156) are provided, projecting into said cavity.

Description

Technical field of the invention

[0001] The present invention relates to a purge circuit fuel injector for an aircraft turbomachine. Technical background

[0002] The state of the art includes in particular documents FR-A1-2 971 039, FR-A 1-3 013 805 and FR-A1-3 067 792.

[0003] A mixture of compressed air and suitable fuel is generally injected into a turbomachine combustion chamber using one or more injectors. The injectors are, for example, fixed to a casing and pass through orifices in a chamber wall to eject fuel into the chamber in the form of a jet of fuel droplets.

[0004] A fuel injector 10, for example a flat jet, such as that shown in figures 1 to 5, conventionally comprises a body 12 of generally elongated shape having an axis of elongation A. The body 12 comprises a first longitudinal end 14 for supplying fuel and a second longitudinal end 16 for ejecting a flat jet of fuel. The body 12 is tubular and comprises an internal bore 18 which opens axially at the end 14 and which is connected to a nozzle 20 for projecting the jet of fuel at the end 16.

[0005] The body may include an air cooling circuit coaxial with the fuel circuit, as described in documents DE-10.2017.200106-A1, DE-10.2013.208069-A1 and JP-2003.247425-A.

[0006] The body 12 may also comprise at least one integrated air purge circuit which comprises an internal cavity 22 connected on the one hand to air inlet orifices 24 located on the body and to at least one air outlet 26 located at the end 16, as described in document EP-2,244,014-A2

[0007] This air circuit has only a purge function and the present invention proposes an improvement to this technology which makes it possible to optimize the operation of a fuel injector, in a simple, efficient and economical manner. Summary of the invention

[0008] The present invention provides a fuel injector according to the subject matter of claim 1.

[0009] Flow disruptors can provide the air circuit with at least one additional function in addition to the purge function. For example, flow disruptors can promote heat exchange between the air and the injector body and thus contribute to cooling the injector body. They can also facilitate the propagation of the fuel jet and thus optimize the performance of the combustion chamber equipped with this injector.

[0010] The injector according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another: the disruptors comprising projecting annular fins extending in this annular portion around said axis of elongation, the disruptors comprise first annular fins projecting on an external cylindrical surface defining the annular portion and second annular fins projecting on an internal cylindrical surface extending around said external surface, the first annular fins are axially spaced from each other along said axis of elongation, the second fins also being axially spaced from each other along this axis and extending in transverse planes passing substantially between the first fins, the cavity comprises two channels diametrically opposite with respect to said axis of elongation and each defining an air outlet at said second end, each of these channels comprising projecting disruptors, said body is formed in a single piece,said first longitudinal end of said body is connected to a fixing base which is formed in one piece with said body, said second end comprises a tubular portion of generally elongated shape having an axis of elongation B substantially perpendicular to said axis of elongation A of said body, said tubular portion having its two open longitudinal ends configured to respectively form two separate fuel flow inlets intended to meet substantially in the middle of said tubular portion which comprises at least one slot for ejecting a flat jet of fuel.

[0011] The present invention also relates to an aircraft turbomachine, comprising a combustion chamber equipped with at least one injector Brief description of the figures

[0012] The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the appended drawings in which: [ Fig. 1 ] there figure 1 is a schematic perspective view of a flat jet fuel injector for an aircraft turbomachine not forming part of the invention as defined by the claims, [ Fig.2 ] there figure 2 is an enlarged schematic view of part of the injector of the figure 1 , [ Fig.3 ] there figure 3 is a schematic perspective and sectional view of the injector of the figure 1 , [ Fig.4 ] there figure 4 is a larger-scale schematic view of a detail of the figure 3 , [ Fig.5 ] there Figure 5 is an even larger scale view of a detail of the injector of the figure 1 , [ Fig.6 ] there figure 6 is a partial schematic view in axial section of an aircraft turbomachine combustion chamber, [ Fig.7 ] there figure 7 is a schematic perspective view in partial section of an embodiment of an injector according to the invention, [ Fig.8 ] there figure 8 is a larger scale view of part of the injector of the figure 7 , And [ Fig.9 ] there figure 9 is a partial schematic perspective view of another embodiment of an injector according to the invention. Detailed description of the invention

[0013] THE figures 1 to 5 have been mentioned in the above but can be used to better understand the invention naturally. These figures as well as the following figures illustrate the invention and show a flat jet injector. Although the invention is particularly suitable for this type of injector, it is not limited to this injector and applies to any type of injector equipped with a purge air circuit.

[0014] There figure 6 shows an environment in which a fuel injector 110 according to the invention can be used. This is a combustion chamber 130 of an aircraft turbomachine such as a helicopter.

[0015] The combustion chamber 130 is arranged inside a casing 132 of the turbomachine and comprises a wall 134 internally defining a combustion space into which a mixture of air and fuel is injected and burned.

[0016] The fuel is injected into the chamber 130 via one or more injectors 110 which are here fixed to the casing 132 and which pass through an orifice 136 in the wall 134.

[0017] The or each injector 110 is of the type shown in figures 1 to 5 and described in the above.

[0018] It comprises a body 112 of generally elongated shape having an axis of elongation A, this body 112 comprising a first longitudinal end 114 for supplying fuel and a second longitudinal end 116 for ejecting a jet of fuel. This second end 116 comprises a nozzle formed by a tubular portion 120 of generally elongated shape having an axis of elongation B substantially perpendicular to the axis of elongation A ( Figure 5 in particular). The tubular portion has its two open longitudinal ends configured to respectively form two separate fuel flow inlets (arrows 121) intended to meet substantially in the middle of the tubular portion which comprises at least one slot 125 for ejecting the fuel jet (arrow 127).

[0019] Preferably, the body 112 and the tubular portion 120 are made of metal and they are obtained in a single piece by machining a metal block, preferably by additive manufacturing.

[0020] The first longitudinal end 116 of the body 112, which here comprises a base 138 for attachment to the casing 132, can also be made in a single piece with the body 112. This attachment base 138 comprises a collar extending around the axis A and pierced with holes for the passage of screws for attaching the injector to the casing 132.

[0021] The body 112 includes an internal longitudinal bore 118 extending along and at the axis A, between the first and second longitudinal ends, and in fluid communication with the ends of the tubular portion 120.

[0022] The body 112 also comprises an internal air passage cavity 122, which comprises an annular portion 139 extending around the bore 118 and channels 140 which open at the end 116 to form the aforementioned purge air outlets. In the example shown, the portion of the cavity 122 extends over a part of the length of the body 112. It extends to the second longitudinal end 116 of the body 112 and is connected to two channels 140 diametrically opposite relative to the axis A, which open at this end 116 so that air is expelled from the injector. When a jet of fuel is ejected by the injector, this jet is surrounded by the air expelled by the same injector. When the injector is not expelling fuel, the expelled air purges the injector's fuel system.

[0023] The air then expels the last drops of fuel and cleans the fuel ejection slot 125 of the tubular portion 120. The air passage cavity 122 is thus likened to a purge circuit.

[0024] At the end opposite the tubular portion 120, the cavity 122 is in fluid communication with an annular row of air supply orifices 124 formed at the periphery of the body and extending around the axis of elongation A.

[0025] THE figures 7 and 8 illustrate a first embodiment of the invention in which air flow disruptors 150 are provided in the cavity 122, and more particularly in its annular portion 139.

[0026] This annular portion 139 is here defined between two cylindrical surfaces 152, 154 extending around each other and around the axis A.

[0027] The disruptors 150 comprise first annular fins 150a projecting from the inner cylindrical surface 152, and second annular fins 150b projecting from the outer cylindrical surface 154.

[0028] The fins 150a are axially spaced from each other along the axis A. The fins 150b are also axially spaced from each other along this axis A and extend in transverse planes passing substantially between the fins 150a.

[0029] The fins 150a, 150b may have a rectangular, triangular or trapezoidal shape in axial section. The fins 150a may have a different shape in section from the fins 150b, as in the example shown. They may have a thickness or axial dimension substantially equal to their height or radial dimension (measured from the axis A).

[0030] The number of fins 150a, 150b on each surface 152, 154 is for example between 3 and 15 and preferably between 5 and 10.

[0031] In operation, the air which enters the portion 139 of the cavity 122, through the orifices 124, must bypass the fins 150a, 150b and undergoes pressure losses due to the baffle effect. This phenomenon contributes to the cooling of the body 112 of the injector 110.

[0032] There figure 9 illustrates an alternative embodiment which can be combined with the previous embodiment.

[0033] Each of the channels 140 has protruding disruptors 156.

[0034] The disruptors 156 of each of the channels 140 comprise several partitions, which are here parallel to each other and substantially parallel to the axis A.

[0035] The number of disruptors 156 or partitions per channel 140 is for example between 3 and 10.

[0036] In operation, the air leaving the purge circuit is guided by the partitions so as to optimize the formation and diffusion of the fuel jet, for example in the direction of a spark plug of the combustion chamber 130 equipped with the injector 110.

[0037] The injector 110 according to the invention can be produced by additive manufacturing for example, and is advantageously a single piece.

Claims

1. A fuel injector (110) for an aircraft turbine engine, comprising a tubular body (112) having an axis of elongation (A) and comprising a first longitudinal end (114) for supplying fuel and a second longitudinal end (116) for ejecting a jet of fuel, said body further comprising an integrated purge air circuit which comprises an internal cavity (122) which is in fluid communication with air supply orifices (124) located on the body (112) and which comprises an annular portion (139) extending around said axis of elongation (A) and connected to air outlet channels (140) opening at said second end (116), characterised in that air flow disruptors (150, 156) are provided projecting into the annular portion (139) of said internal cavity (122) and in the channels (140), the disruptors (156) of each of the channels (140) comprising several partitions, said partitions being parallel to each other and substantially parallel to said axis of elongation (A).

2. The injector (110) according to claim 1, wherein the disruptors (150) comprise projecting annular fins (150a, 150b) extending into the annular portion (139) about said axis of elongation.

3. The injector (110) according to claim 2, wherein the disruptors (150) comprise first annular fins (150a) projecting from an outer cylindrical surface (152) defining said portion, and second annular fins (150b) projecting from an inner cylindrical surface (154) extending around said outer surface.

4. The injector (110) according to claim 3, wherein the first annular fins (150a) are axially spaced apart along said axis of elongation, the second fins (150b) also being axially spaced apart along said axis and extending in transverse planes passing substantially between the first fins.

5. The injector (110) according to one of the preceding claims, wherein said cavity (122) comprises two channels (140) diametrically opposed with respect to said axis of elongation (A) and each defining an air outlet at said second end (116).

6. The injector (110) according to one of the preceding claims, wherein said body (112) is formed in a single piece.

7. The injector (110) according to one of the preceding claims, wherein said first longitudinal end (114) of said body (112) is connected to an attachment base (138) which is formed integrally with said body.

8. An aircraft turbine engine, comprising a combustion chamber equipped with at least one injector (110) according to one of the preceding claims.

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