EP1314933B1 - Multi-stage injection system of an air/fuel mixture in a gas turbine combustion chamber - Google Patents

Multi-stage injection system of an air/fuel mixture in a gas turbine combustion chamber Download PDF

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Publication number
EP1314933B1
EP1314933B1 EP02292866A EP02292866A EP1314933B1 EP 1314933 B1 EP1314933 B1 EP 1314933B1 EP 02292866 A EP02292866 A EP 02292866A EP 02292866 A EP02292866 A EP 02292866A EP 1314933 B1 EP1314933 B1 EP 1314933B1
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EP
European Patent Office
Prior art keywords
injector
fuel
air
fuel feed
orifices
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP02292866A
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German (de)
French (fr)
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EP1314933A1 (en
Inventor
Etienne David
Marion Michau
José Rodrigues
Denis Sandelis
Alain Tiepel
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Safran Transmission Systems SAS
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Hispano Suiza SA
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
    • F23R3/28—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply
    • F23R3/286—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply having fuel-air premixing devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
    • F23D11/10—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour
    • F23D11/106—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour medium and fuel meeting at the burner outlet
    • F23D11/107—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour medium and fuel meeting at the burner outlet at least one of both being subjected to a swirling motion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
    • F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
    • F23R3/04—Air inlet arrangements
    • F23R3/10—Air inlet arrangements for primary air
    • F23R3/12—Air inlet arrangements for primary air inducing a vortex
    • F23R3/14—Air inlet arrangements for primary air inducing a vortex by using swirl vanes

Definitions

  • the present invention relates to the general field of fuel injection systems in a combustion chamber of a gas turbine engine. It is more particularly an injection system comprising in particular an aerodynamic fuel injector multi-point feed fuel.
  • injection systems include fuel injectors and air intake means downstream of the injectors.
  • fuel injectors There are two main categories of fuel injectors: the so-called “aeromechanical” injectors designed to deliver two fuel flows according to the engine speeds, and the so-called “aerodynamic” injectors which comprise only one fuel circuit, whatever the engine speed.
  • some so-called “aerodynamic” injectors have, at their end or nose, air supply channels to directly deliver an air / fuel mixture.
  • the present invention relates more particularly to injection systems comprising so-called "aerodynamic" injectors belonging to the latter category.
  • the air intake means known from the prior art (as for example that disclosed in U.S. 4,425,755 ) generally comprise primary and secondary tendrils which deliver a swirling air flow at the outlet of the fuel injector.
  • a venturi separating these two tendrils accelerates the flow of air from the primary swirler and a bowl mounted downstream of the secondary swirler allows the mounting of the injector on the bottom of the combustion chamber while aiming to prevent a rise in the combustion flame of the air / fuel mixture to the injector.
  • This type of injection system has disadvantages.
  • the air / fuel mixture delivered at the injector outlet is generally not homogeneous, thus increasing the pollutant emissions of the engine.
  • the fuel flow rate at the injector outlet is also insufficient, especially for low flow rates, which leads to risks of coking at the nose of the injector and causes heterogeneity of the air / fuel mixture.
  • a low fuel flow rate also has the disadvantage of increasing the risk of a rise in the combustion flame of the air / fuel mixture to the end of the injector which is detrimental to the proper functioning of the fuel. gas turbine.
  • traces of coking appear between the body of the injector and the bowl.
  • the present invention therefore aims to overcome such drawbacks by proposing an injection system whose fuel injector makes it possible to obtain a better homogenization of the air / fuel mixture and a greater speed of flow of the fuel at its outlet.
  • a system for injecting an air / fuel mixture into a turbomachine combustion chamber comprising an injector comprising an axial internal volume which opens at one end via an axial outlet for the air mixture. /fuel ; a first fuel supply stage with a plurality of first fuel supply ports which open into the internal volume, are distributed around an axis of the injector and are connected by fuel supply channels at a fuel inlet in the injector; and at least one air supply channel which opens into the internal volume and is connected to an air inlet in the injector, characterized in that the injector further comprises at least a second supply stage in fuel with a plurality of second fuel supply ports which open into the internal volume, are distributed around the axis of the injector, and are connected to the fuel inlet in the injector through channels which are at least partly confused with the fuel supply channels of the first stage.
  • the second fuel supply stage makes it possible to multiply the number of fuel supply points in the internal volume of the injector around the axis of the latter. Homogenization of the air / fuel mixture is thus improved.
  • the passage in which the fuel supply openings open has a decrease in section in the direction of flow of the fuel. This feature makes it possible to increase the flow rate of the fuel to improve the resistance of the injector to coking, and to make the fuel ply more homogeneous, especially for low fuel flow rates.
  • the second fuel supply orifices are axially offset with respect to the first fuel supply orifices.
  • the second fuel supply ports preferably have angular positions about the axis of the injector offset from those of the first fuel supply ports.
  • the fuel supply channels are oriented, in their terminal parts adjacent to the first and second fuel supply ports, substantially tangentially with respect to the wall of the internal volume. This characteristic makes it possible to obtain a rotation of the fuel in the internal volume and thus improves the flow rate and the homogeneity of the air / fuel mixture.
  • the injector comprises a rear part in which the air supply channel or channels are formed, at least one ring in which the first and second fuel supply stages are formed and which is introduced into a formed housing. at the downstream end of the rear portion, and a front portion which connects to the rear portion, the ring being immobilized axially between the rear portion and the front portion of the injector.
  • each fuel supply stage comprises four fuel supply orifices distributed regularly around the axis of the injector.
  • the system according to the invention further comprises a bushing surrounding at least a part of the injector, a divergent forming bowl for mounting the injection system on a bottom of the combustion chamber, at least one air swirl interposed between the sleeve and the bowl, and a venturi formed between the part of the injector surrounded by the sleeve and the bowl.
  • a passage for air is provided between the socket and the portion of the injector surrounded by the socket to prevent coke from forming at the nose of the injector, and through holes. of air are formed in the wall of the diverging bowl.
  • the figure 1 illustrates an injection system 2 according to the invention mounted in a combustion chamber 4 of a gas turbine engine used in a turbojet for example.
  • the combustion chamber 4 for example of the annular type, is delimited by internal and external walls (not shown in the drawing) joined by a chamber bottom 6.
  • the latter comprises a plurality of openings 6a of axis 8 regularly spaced around the axis of the motor.
  • an injection system 2 according to the invention for injecting an air / fuel mixture into the combustion chamber 4.
  • the gases resulting from the combustion of this air / fuel mixture flow towards the downstream in the combustion chamber 4 and are then discharged to a high-pressure turbine (not shown).
  • annular baffle 10 is mounted in each of the openings 6a.
  • This deflector is disposed in the combustion chamber 4 parallel to the chamber bottom 6.
  • a divergent bowl 20 is also mounted inside the opening 6a. It comprises a wall 21 flared downstream in the extension of a cylindrical wall 22 disposed coaxially with the axis 8 of the opening 6a. At its downstream end, the wall 21 of the bowl has a flange 23 which, with a facing wall 24, defines an annular recess or U-shaped bowl flange.
  • the cylindrical wall 22 of the bowl 20 surrounds a venturi 30 of axis 8.
  • the venturi 30 delimits the air flows coming from a primary swirler 32 and a secondary swirler 34.
  • the primary swirler 32 is arranged upstream of the venturi 30 and delivers a flow of air inside the venturi.
  • the secondary swirler 34 is disposed upstream of the cylindrical wall 22 of the bowl 20 and delivers a flow of air between the venturi 30 and the cylindrical wall 22.
  • the primary swirler 32 is secured upstream of a retaining piece 40 which has an annular groove 42 open on the side of the axis 8 of the opening 6a and in which is mounted a sleeve 44 surrounding at least a portion of the end or nose of a fuel injector 50.
  • the injection system may further be provided with a fairing typically formed of a cap 46. This fairing minimizes the losses of fuel. load of air bypassing the injector and to ensure a good supply of the chamber bottom.
  • the fuel injector 50 of axis XX coincides with the axis 8 of the opening 6a, is aerodynamic type, that is to say it delivers only one fuel flow whatever the regime engine operation.
  • the injector is typically formed of a tubular portion 52 supplying fuel to an injector nose 54, at which the fuel mixes with air before receiving the air from the primary and secondary tendrils and being injected. in the combustion chamber 4.
  • FIGS 2 to 6 which more particularly illustrate an embodiment of the fuel injector nose of the injection system according to the invention.
  • the nozzle nose 54 has an axial internal volume 56 which opens at one end via an axial outlet 58 for the air / fuel mixture.
  • At the end of the nose opposite that having the axial outlet 58 is provided at least one fuel inlet 60 in the form of a cylindrical recess, for example.
  • This inlet 60 is supplied with fuel by the tubular part of the fuel injector.
  • Fuel supply channels 62 open into the fuel inlet 60 and are connected to a plurality of first fuel supply ports 64 forming a first fuel supply stage. These first orifices are distributed around the axis XX of the injector and open into the internal volume 56.
  • At least one air supply channel 66 connected to an air inlet 68 in the injector opens also in the internal volume 56.
  • the fuel injector 50 comprises, at its nose 54, at least a second fuel supply stage with a plurality of second fuel supply ports 70 which open in the volume internal 56. These second orifices are distributed around the axis XX of the injector and are connected to the fuel inlet 60 in the injector by fuel supply channels 72 which are at least partially merged with the fuel supply channels 62 of the first fuel supply stage.
  • each fuel supply stage advantageously comprises four feed orifices, fuel 64, 70 connected to the fuel supply channels 62, 72 and distributed regularly around the axis XX of the injector.
  • the feed channels 62, 72 are preferably arranged alternately with four air supply channels 66.
  • first 64 and second 70 fuel supply ports on the one hand, and the air supply duct or channels 66, on the other hand, open in two coaxial passages 74 and 76, respectively. formed in the inner volume 56.
  • the air supply channels 66 open into a central passage 76
  • the first and second fuel supply ports open into an annular passage 74 surrounding the passage. central 76.
  • the annular passage 74 into which the fuel supply openings open has a reduction of section 74a in the direction of flow of the fuel in order to form a convergent allowing the acceleration of the fuel. at its exit from this annular passage.
  • the second fuel supply stage can be axially offset from the first stage, so that the second fuel supply ports 70 are axially offset from the first fuel supply ports 64.
  • This shift of the stages fuel supply can be provided when, for reasons of space, it is not possible to have all the supply ports 64, 70 in the same axial plane.
  • the second fuel supply ports 70 preferably have angular positions about the axis XX of the injector offset from those of the first fuel supply ports 64. In this way, the distribution fuel around the axis of the injector and thus the homogeneity of the air / fuel mixture are improved.
  • the fuel supply channels 62, 72 each comprise a first part, respectively 62a and 72a, extending parallel to the axis XX of the injector and connected to the fuel inlet 60 in the injector, and a second portion, respectively 62b and 72b, which connects the first portion to a fuel supply port 64, 70.
  • first parts 62a, 72a of the fuel supply channels 62, 72 are at least partially merged.
  • these fuel supply channels are oriented substantially tangentially with respect to the wall of the internal volume 56.
  • the fuel flowing in these channels is rotated before its introduction into the internal volume which allows to increase its flow rate and thus to promote the homogeneity of the air / fuel mixture.
  • the arrangement of the air supply channel (s) 66 is particularly illustrated by the Figures 3 and 6 . These channels open into the internal volume 56 in a direction which is substantially tangential to the wall of the internal volume and which is inclined downstream relative to a plane normal to the axis XX of the injector. This particular arrangement also improves the homogeneity and flow velocity of the air / fuel mixture.
  • the injector nose is essentially formed of three parts: a rear part 78 in which the air supply duct or ducts 66 are formed, at least one ring 80 in which the first and second fuel supply stage and which is introduced into a housing 82 formed at the downstream end of the rear portion, and a front portion 84 which connects to the rear portion, the ring being immobilized axially between the rear portion and the front part.
  • the nose of the injector comprises, at the ring 80, two fuel supply stages.
  • the nose of the injector, and more particularly the ring 80 has more than two stages of fuel supply so as to further multiply the number of fuel supply points in the internal volume of the fuel. the injector.
  • the additional floors can be shifted axially relative to each other to increase the number of fuel supply points in the internal volume of the injector.
  • FIG. 1 Another advantageous features of the injection system according to the invention are represented on the figure 1 .
  • at least one passage for air is arranged between the sleeve 44 and the nose portion surrounded by it.
  • This passage makes it possible to carry out an anti-coking purge, that is to say that it prevents fuel from coking at the nose of the injector, especially at low fuel flow rates.
  • This passage for the air can for example be made in the form of a plurality of orifices 48 regularly distributed around the nose and opening in the vicinity of the axial outlet 58 thereof in a direction substantially parallel to the axis XX of the injector 50. In order to accelerate the flow of the air passing through these orifices 48, a reduction in section of this passage in the direction of flow of the air may be provided.
  • air passage holes 25 are formed in the wall 21 of the bowl 20 to effect an anti-coking purge at the bowl. These holes open into the combustion chamber in a direction which may be tilted with respect to the X-X axis and be tangential to the flared wall 21 of the bowl to avoid any risk of coking.
  • air passage holes 26 are formed in the facing wall 24 of the bowl flange to feed it, and more particularly the annular baffle 10, with air. These holes 26 open for example substantially parallel to the X-X axis of the injector so that the air passing through them hits the flange 23 of the wall 21 of the bowl and flows along the annular baffle 10.
  • the holes 25, 26 and air passage holes 48 of the various elements of the injection system, as well as air slots 36, 38 respectively for the primary 32 and secondary 34 tendrils may be distributed along N 360 angular sectors. / N ° each. More specifically, for each angular sector, the bowl 20 may for example comprise n air passage holes 25 of identical shapes to each other (for example circular, elliptical, ...) and opening out parallel to each other. This same principle can be adopted for other holes and air passage slots.
  • the figure 7 schematically illustrates, in a plane P perpendicular to the axis XX, an example of distribution of these different air passages.
  • the air passages of an angular sector of 60 ° are represented; they comprise: three orifices 48 arranged between the bush 44 and the nose part surrounded by the latter, two air slots 36 for the primary swirler, three air slots 38 for the secondary swirler, four holes 25 for passing through air formed in the wall 21 of the bowl, and eight air passage holes 26 formed in the facing wall 24 of the bowl collar.
  • the distribution of these different air passages is regular around the axis XX. They can be made directly in the foundry.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fuel-Injection Apparatus (AREA)

Description

La présente invention se rapporte au domaine général des systèmes d'injection de carburant dans une chambre de combustion d'un moteur de turbine à gaz. Elle vise plus particulièrement un système d'injection comportant notamment un injecteur de carburant aérodynamique à alimentation multi-points en carburant.The present invention relates to the general field of fuel injection systems in a combustion chamber of a gas turbine engine. It is more particularly an injection system comprising in particular an aerodynamic fuel injector multi-point feed fuel.

De façon connue, la chambre de combustion d'un moteur de turbine à gaz est pourvue de plusieurs systèmes d'injection lui permettant d'être alimentée en carburant et en air à tous les régimes de fonctionnement du moteur. Les systèmes d'injection comportent notamment des injecteurs de carburant et des moyens d'admission d'air en aval des injecteurs. Il existe deux catégories principales d'injecteurs de carburant : les injecteurs dits « aéromécaniques » conçus pour délivrer deux débits de carburant suivant les régimes du moteur, et les injecteurs dits « aérodynamiques » qui ne comportent qu'un seul circuit de carburant, quel que soit le régime du moteur. En outre, certains injecteurs dits « aérodynamiques » présentent, au niveau de leur extrémité ou nez, des canaux d'alimentation en air afin de délivrer directement un mélange air/carburant. La présente invention vise plus particulièrement les systèmes d'injection comportant des injecteurs dits « aérodynamiques » appartenant à cette dernière catégorie.In known manner, the combustion chamber of a gas turbine engine is provided with several injection systems allowing it to be supplied with fuel and air at all operating speeds of the engine. Injection systems include fuel injectors and air intake means downstream of the injectors. There are two main categories of fuel injectors: the so-called "aeromechanical" injectors designed to deliver two fuel flows according to the engine speeds, and the so-called "aerodynamic" injectors which comprise only one fuel circuit, whatever the engine speed. In addition, some so-called "aerodynamic" injectors have, at their end or nose, air supply channels to directly deliver an air / fuel mixture. The present invention relates more particularly to injection systems comprising so-called "aerodynamic" injectors belonging to the latter category.

Les moyens d'admission d'air connus de l'art antérieur (comme par exemple celui divulgué dans US-4 425 755 ) comportent en général des vrilles primaire et secondaire qui délivrent un flux d'air tourbillonnant à la sortie de l'injecteur de carburant. Un venturi séparant ces deux vrilles permet d'accélérer l'écoulement d'air issu de la vrille primaire et un bol monté en aval de la vrille secondaire permet le montage de l'injecteur sur le fond de chambre de combustion tout en visant à empêcher une remontée de la flamme de combustion du mélange air/carburant vers l'injecteur.The air intake means known from the prior art (as for example that disclosed in U.S. 4,425,755 ) generally comprise primary and secondary tendrils which deliver a swirling air flow at the outlet of the fuel injector. A venturi separating these two tendrils accelerates the flow of air from the primary swirler and a bowl mounted downstream of the secondary swirler allows the mounting of the injector on the bottom of the combustion chamber while aiming to prevent a rise in the combustion flame of the air / fuel mixture to the injector.

Ce type de système d'injection présente des inconvénients. En particulier, le mélange air/carburant délivré en sortie d'injecteur n'est généralement pas homogène, augmentant ainsi les émissions polluantes du moteur. La vitesse d'écoulement du carburant en sortie d'injecteur est en outre insuffisante, notamment pour les faibles débits, ce qui entraîne des risques de cokéfaction au niveau du nez de l'injecteur et engendre une hétérogénéité du mélange air/carburant. Une faible vitesse d'écoulement du carburant a également pour inconvénient d'augmenter les risques d'une remontée de la flamme de combustion du mélange air/carburant jusqu'à l'extrémité de l'injecteur ce qui est préjudiciable au bon fonctionnement de la turbine à gaz. De plus, lors d'allumages répétés sur ce type de système d'injection, on constate que des traces de cokéfaction apparaissent entre le corps de l'injecteur et le bol.This type of injection system has disadvantages. In particular, the air / fuel mixture delivered at the injector outlet is generally not homogeneous, thus increasing the pollutant emissions of the engine. The fuel flow rate at the injector outlet is also insufficient, especially for low flow rates, which leads to risks of coking at the nose of the injector and causes heterogeneity of the air / fuel mixture. A low fuel flow rate also has the disadvantage of increasing the risk of a rise in the combustion flame of the air / fuel mixture to the end of the injector which is detrimental to the proper functioning of the fuel. gas turbine. In addition, during repeated ignitions on this type of injection system, it is found that traces of coking appear between the body of the injector and the bowl.

Objet et résumé de l'inventionObject and summary of the invention

La présente invention vise donc à pallier de tels inconvénients en proposant un système d'injection dont l'injecteur de carburant permet d'obtenir une meilleure homogénéisation du mélange air/carburant et une plus grande vitesse d'écoulement du carburant à sa sortie.The present invention therefore aims to overcome such drawbacks by proposing an injection system whose fuel injector makes it possible to obtain a better homogenization of the air / fuel mixture and a greater speed of flow of the fuel at its outlet.

A cet effet, il est prévu un système d'injection d'un mélange air/carburant dans une chambre de combustion de turbomachine, comprenant un injecteur comportant un volume interne axial qui s'ouvre à une extrémité par une sortie axiale pour le mélange air/carburant ; un premier étage d'alimentation en carburant avec une pluralité de premiers orifices d'alimentation en carburant qui s'ouvrent dans le volume interne, sont répartis autour d'un axe de l'injecteur et sont reliés par des canaux d'alimentation en carburant à une entrée de carburant dans l'injecteur ; et au moins un canal d'alimentation en air qui s'ouvre dans le volume interne et est relié à une entrée d'air dans l'injecteur, caractérisé en ce que l'injecteur comporte en outre au moins un deuxième étage d'alimentation en carburant avec une pluralité de deuxièmes orifices d'alimentation en carburant qui s'ouvrent dans le volume interne, sont répartis autour de l'axe de l'injecteur, et sont reliés à l'entrée de carburant dans l'injecteur par des canaux d'alimentation en carburant qui sont au moins en partie confondus avec les canaux d'alimentation en carburant du premier étage.For this purpose, there is provided a system for injecting an air / fuel mixture into a turbomachine combustion chamber, comprising an injector comprising an axial internal volume which opens at one end via an axial outlet for the air mixture. /fuel ; a first fuel supply stage with a plurality of first fuel supply ports which open into the internal volume, are distributed around an axis of the injector and are connected by fuel supply channels at a fuel inlet in the injector; and at least one air supply channel which opens into the internal volume and is connected to an air inlet in the injector, characterized in that the injector further comprises at least a second supply stage in fuel with a plurality of second fuel supply ports which open into the internal volume, are distributed around the axis of the injector, and are connected to the fuel inlet in the injector through channels which are at least partly confused with the fuel supply channels of the first stage.

De la sorte, le deuxième étage d'alimentation en carburant permet de multiplier le nombre de points d'alimentation en carburant dans le volume interne de l'injecteur autour de l'axe de celui-ci. L'homogénéisation du mélange air/carburant s'en trouve donc améliorée.In this way, the second fuel supply stage makes it possible to multiply the number of fuel supply points in the internal volume of the injector around the axis of the latter. Homogenization of the air / fuel mixture is thus improved.

Les premiers et deuxièmes orifices d'alimentation en carburant, d'une part, et le ou les canaux d'alimentation en air, d'autre part, s'ouvrent dans deux passages coaxiaux formés dans le volume interne. Selon une disposition avantageuse de l'invention, le passage dans lequel s'ouvrent les orifices d'alimentation en carburant présente une diminution de section dans le sens d'écoulement du carburant. Cette caractéristique permet d'augmenter la vitesse d'écoulement du carburant pour améliorer la tenue de l'injecteur à la cokéfaction, et de rendre la nappe de carburant plus homogène, notamment pour les faibles débits de carburant.The first and second fuel supply ports, on the one hand, and the air supply channel (s), on the other hand, open in two coaxial passages formed in the internal volume. According to an advantageous arrangement of the invention, the passage in which the fuel supply openings open has a decrease in section in the direction of flow of the fuel. This feature makes it possible to increase the flow rate of the fuel to improve the resistance of the injector to coking, and to make the fuel ply more homogeneous, especially for low fuel flow rates.

Selon une autre disposition avantageuse de l'invention, les deuxièmes orifices d'alimentation en carburant sont axialement décalés par rapport aux premiers orifices d'alimentation en carburant. Dans ce cas, les deuxièmes orifices d'alimentation en carburant ont de préférence des positions angulaires autour de l'axe de l'injecteur décalées par rapport à celles des premiers orifices d'alimentation en carburant. Ces dispositions avantageuses permettent de favoriser la répartition du carburant autour de l'axe de l'injecteur et donc l'homogénéité du mélange air/carburant.According to another advantageous arrangement of the invention, the second fuel supply orifices are axially offset with respect to the first fuel supply orifices. In this case, the second fuel supply ports preferably have angular positions about the axis of the injector offset from those of the first fuel supply ports. These advantageous arrangements make it possible to promote the distribution of the fuel around the axis of the injector and thus the homogeneity of the air / fuel mixture.

Selon encore une autre disposition avantageuse de l'invention, les canaux d'alimentation en carburant sont orientés, dans leurs parties terminales adjacentes aux premiers et deuxièmes orifices d'alimentation en carburant, sensiblement tangentiellement par rapport à la paroi du volume interne. Cette caractéristique permet d'obtenir une mise en rotation du carburant dans le volume interne et améliore ainsi la vitesse d'écoulement et l'homogénéité du mélange air/carburant.According to yet another advantageous arrangement of the invention, the fuel supply channels are oriented, in their terminal parts adjacent to the first and second fuel supply ports, substantially tangentially with respect to the wall of the internal volume. This characteristic makes it possible to obtain a rotation of the fuel in the internal volume and thus improves the flow rate and the homogeneity of the air / fuel mixture.

De préférence, l'injecteur comporte une partie arrière dans laquelle sont formés le ou les canaux d'alimentation en air, au moins une bague dans laquelle sont formés les premier et deuxième étages d'alimentation en carburant et qui est introduite dans un logement formé à l'extrémité aval de la partie arrière, et une partie avant qui se raccorde à la partie arrière, la bague étant immobilisée axialement entre la partie arrière et la partie avant de l'injecteur.Preferably, the injector comprises a rear part in which the air supply channel or channels are formed, at least one ring in which the first and second fuel supply stages are formed and which is introduced into a formed housing. at the downstream end of the rear portion, and a front portion which connects to the rear portion, the ring being immobilized axially between the rear portion and the front portion of the injector.

Selon encore une caractéristique avantageuse de l'invention, chaque étage d'alimentation en carburant comprend quatre orifices d'alimentation en carburant répartis de façon régulière autour de l'axe de l'injecteur.According to another advantageous characteristic of the invention, each fuel supply stage comprises four fuel supply orifices distributed regularly around the axis of the injector.

Le système selon l'invention comporte en outre une douille entourant au moins une partie de l'injecteur, un bol formant divergent pour le montage du système d'injection sur un fond de chambre de combustion, au moins une vrille d'air interposée entre la douille et le bol, et un venturi formé entre la partie de l'injecteur entourée par la douille et le bol. De préférence, un passage pour de l'air est aménagé entre la douille et la partie de l'injecteur entourée par la douille afin d'empêcher que de la coke se forme au niveau du nez de l'injecteur, et des trous de passage d'air sont formés dans la paroi du bol formant divergent.The system according to the invention further comprises a bushing surrounding at least a part of the injector, a divergent forming bowl for mounting the injection system on a bottom of the combustion chamber, at least one air swirl interposed between the sleeve and the bowl, and a venturi formed between the part of the injector surrounded by the sleeve and the bowl. Preferably, a passage for air is provided between the socket and the portion of the injector surrounded by the socket to prevent coke from forming at the nose of the injector, and through holes. of air are formed in the wall of the diverging bowl.

Brève description des dessinsBrief description of the drawings

D'autres caractéristiques et avantages de la présente invention ressortiront de la description faite ci-dessous, en référence aux dessins annexés qui en illustrent un exemple de réalisation dépourvu de tout caractère limitatif. Sur les figures :

  • la figure 1 est vue en coupe du système d'injection selon l'invention monté dans une chambre de combustion d'un moteur à turbine à gaz ;
  • la figure 2 est une vue en coupe longitudinale d'un mode de réalisation du nez de l'injecteur de carburant équipant le système d'injection selon l'invention ;
  • les figures 3, 4 et 5 sont des vues en coupe de la figure 2 respectivement selon III-III, IV-IV et V-V ;
  • la figure 6 est une vue en coupe selon VI-VI de la figure 3 ;
  • la figure 7 est une vue en perspective et en éclaté du nez de l'injecteur de la figure 2 ; et
  • la figure 8 représente schématiquement un exemple de répartition des différents passages alimentant en air le système d'injection de la figure 1.
Other features and advantages of the present invention will emerge from the description given below, with reference to the accompanying drawings which illustrate an embodiment having no limiting character. In the figures:
  • the figure 1 is seen in section of the injection system according to the invention mounted in a combustion chamber of a gas turbine engine;
  • the figure 2 is a longitudinal sectional view of an embodiment of the nose of the fuel injector fitted to the injection system according to the invention;
  • the Figures 3, 4 and 5 are sectional views of the figure 2 respectively according to III-III, IV-IV and VV;
  • the figure 6 is a sectional view according to VI-VI of the figure 3 ;
  • the figure 7 is a perspective and exploded view of the nose of the injector of the figure 2 ; and
  • the figure 8 schematically represents an example of distribution of the different passages supplying air to the injection system of the figure 1 .

Description détaillée d'un mode de réalisationDetailed description of an embodiment

La figure 1 illustre un système d'injection 2 selon l'invention monté dans une chambre de combustion 4 d'un moteur à turbine à gaz utilisé dans un turboréacteur par exemple.The figure 1 illustrates an injection system 2 according to the invention mounted in a combustion chamber 4 of a gas turbine engine used in a turbojet for example.

La chambre de combustion 4, par exemple du type annulaire, est délimitée par des parois interne et externe (non représentées sur le dessin) réunies par un fond de chambre 6. Ce dernier comporte une pluralité d'ouvertures 6a d'axe 8 régulièrement espacées autour de l'axe du moteur. Dans chacune des ouvertures 6a est monté un système d'injection 2 selon l'invention destiné à injecter un mélange air/carburant dans la chambre de combustion 4. Les gaz issus de la combustion de ce mélange air/carburant s'écoulent vers l'aval dans la chambre de combustion 4 et sont ensuite évacués vers une turbine haute-pression (non représentée).The combustion chamber 4, for example of the annular type, is delimited by internal and external walls (not shown in the drawing) joined by a chamber bottom 6. The latter comprises a plurality of openings 6a of axis 8 regularly spaced around the axis of the motor. In each of the openings 6a is mounted an injection system 2 according to the invention for injecting an air / fuel mixture into the combustion chamber 4. The gases resulting from the combustion of this air / fuel mixture flow towards the downstream in the combustion chamber 4 and are then discharged to a high-pressure turbine (not shown).

De façon connue en soi, un déflecteur annulaire 10 est monté dans chacune des ouvertures 6a. Ce déflecteur est disposé dans la chambre de combustion 4 parallèlement au fond de chambre 6. Un bol 20 formant divergent est également monté à l'intérieur de l'ouverture 6a. Il comporte une paroi 21 évasée vers l'aval dans le prolongement d'une paroi cylindrique 22 disposée coaxialement à l'axe 8 de l'ouverture 6a. A son extrémité aval, la paroi 21 du bol présente un rebord 23 qui, avec une paroi en regard 24, délimite un renfoncement annulaire ou collerette de bol à section en U.In a manner known per se, an annular baffle 10 is mounted in each of the openings 6a. This deflector is disposed in the combustion chamber 4 parallel to the chamber bottom 6. A divergent bowl 20 is also mounted inside the opening 6a. It comprises a wall 21 flared downstream in the extension of a cylindrical wall 22 disposed coaxially with the axis 8 of the opening 6a. At its downstream end, the wall 21 of the bowl has a flange 23 which, with a facing wall 24, defines an annular recess or U-shaped bowl flange.

La paroi cylindrique 22 du bol 20 entoure un venturi 30 d'axe 8. Le venturi 30 délimite les écoulements d'air issus d'une vrille primaire 32 et d'une vrille secondaire 34. La vrille primaire 32 est disposée en amont du venturi 30 et délivre un flux d'air à l'intérieur du venturi. La vrille secondaire 34 est disposée en amont de la paroi cylindrique 22 du bol 20 et délivre un flux d'air entre le venturi 30 et la paroi cylindrique 22.The cylindrical wall 22 of the bowl 20 surrounds a venturi 30 of axis 8. The venturi 30 delimits the air flows coming from a primary swirler 32 and a secondary swirler 34. The primary swirler 32 is arranged upstream of the venturi 30 and delivers a flow of air inside the venturi. The secondary swirler 34 is disposed upstream of the cylindrical wall 22 of the bowl 20 and delivers a flow of air between the venturi 30 and the cylindrical wall 22.

La vrille primaire 32 est solidaire en amont d'une pièce de retenue 40 qui présente une rainure annulaire 42 ouverte du côté de l'axe 8 de l'ouverture 6a et dans laquelle est montée une douille 44 entourant au moins une partie de l'extrémité ou nez d'un injecteur de carburant 50. Le système d'injection peut en outre être muni d'un carénage typiquement formé d'une casquette 46. Ce carénage permet de minimiser les pertes de charge de l'air de contournement de l'injecteur et de garantir une bonne alimentation du fond de chambre.The primary swirler 32 is secured upstream of a retaining piece 40 which has an annular groove 42 open on the side of the axis 8 of the opening 6a and in which is mounted a sleeve 44 surrounding at least a portion of the end or nose of a fuel injector 50. The injection system may further be provided with a fairing typically formed of a cap 46. This fairing minimizes the losses of fuel. load of air bypassing the injector and to ensure a good supply of the chamber bottom.

L'injecteur de carburant 50, d'axe X-X confondu avec l'axe 8 de l'ouverture 6a, est de type aérodynamique, c'est à dire qu'il ne délivre qu'un seul débit de carburant quel que soit le régime de fonctionnement du moteur. L'injecteur est typiquement formé d'une partie tubulaire 52 alimentant en carburant un nez d'injecteur 54, au niveau duquel le carburant se mélange avec de l'air avant de recevoir l'air des vrilles primaire et secondaire et d'être injecté dans la chambre de combustion 4.The fuel injector 50, of axis XX coincides with the axis 8 of the opening 6a, is aerodynamic type, that is to say it delivers only one fuel flow whatever the regime engine operation. The injector is typically formed of a tubular portion 52 supplying fuel to an injector nose 54, at which the fuel mixes with air before receiving the air from the primary and secondary tendrils and being injected. in the combustion chamber 4.

On se réfère aux figures 2 à 6 qui illustrent plus particulièrement un mode de réalisation du nez d'injecteur de carburant du système d'injection selon l'invention.We refer to Figures 2 to 6 which more particularly illustrate an embodiment of the fuel injector nose of the injection system according to the invention.

Le nez d'injecteur 54 comporte un volume interne axial 56 qui s'ouvre à une extrémité par une sortie axiale 58 pour le mélange air/carburant. A l'extrémité du nez opposée à celle comportant la sortie axiale 58, est aménagée au moins une entrée de carburant 60 se présentant sous la forme d'un évidement cylindrique par exemple. Cette entrée 60 est alimentée en carburant par la partie tubulaire de l'injecteur de carburant. Des canaux d'alimentation en carburant 62 débouchent dans l'entrée de carburant 60 et sont reliés à une pluralité de premiers orifices d'alimentation en carburant 64 formant un premier étage d'alimentation en carburant. Ces premiers orifices sont répartis autour de l'axe X-X de l'injecteur et s'ouvrent dans le volume interne 56. Au moins un canal d'alimentation en air 66 relié à une entrée d'air 68 dans l'injecteur s'ouvre également dans le volume interne 56.The nozzle nose 54 has an axial internal volume 56 which opens at one end via an axial outlet 58 for the air / fuel mixture. At the end of the nose opposite that having the axial outlet 58 is provided at least one fuel inlet 60 in the form of a cylindrical recess, for example. This inlet 60 is supplied with fuel by the tubular part of the fuel injector. Fuel supply channels 62 open into the fuel inlet 60 and are connected to a plurality of first fuel supply ports 64 forming a first fuel supply stage. These first orifices are distributed around the axis XX of the injector and open into the internal volume 56. At least one air supply channel 66 connected to an air inlet 68 in the injector opens also in the internal volume 56.

Conformément à l'invention, l'injecteur de carburant 50 comporte, au niveau de son nez 54, au moins un deuxième étage d'alimentation en carburant avec une pluralité de deuxièmes orifices d'alimentation en carburant 70 qui s'ouvrent dans le volume interne 56. Ces deuxièmes orifices sont répartis autour de l'axe X-X de l'injecteur et sont reliés à l'entrée de carburant 60 dans l'injecteur par des canaux d'alimentation en carburant 72 qui sont au moins en partie confondus avec les canaux d'alimentation en carburant 62 du premier étage d'alimentation en carburant.According to the invention, the fuel injector 50 comprises, at its nose 54, at least a second fuel supply stage with a plurality of second fuel supply ports 70 which open in the volume internal 56. These second orifices are distributed around the axis XX of the injector and are connected to the fuel inlet 60 in the injector by fuel supply channels 72 which are at least partially merged with the fuel supply channels 62 of the first fuel supply stage.

Comme l'illustre la figure 3, chaque étage d'alimentation en carburant comprend avantageusement quatre orifices d'alimentation en carburant 64, 70 reliés aux canaux d'alimentation en carburant 62, 72 et répartis de façon régulière autour de l'axe X-X de l'injecteur. Les canaux d'alimentation 62, 72 sont de préférence disposés en alternance avec quatre canaux d'alimentation en air 66.As illustrated by figure 3 each fuel supply stage advantageously comprises four feed orifices, fuel 64, 70 connected to the fuel supply channels 62, 72 and distributed regularly around the axis XX of the injector. The feed channels 62, 72 are preferably arranged alternately with four air supply channels 66.

Par ailleurs, les premiers 64 et deuxièmes 70 orifices d'alimentation en carburant, d'une part, et le ou les canaux d'alimentation en air 66, d'autre part, s'ouvrent dans deux passages coaxiaux, respectivement 74 et 76, formés dans le volume interne 56. Plus précisément, les canaux d'alimentation en air 66 s'ouvrent dans un passage central 76, et les premiers et deuxièmes orifices d'alimentation en carburant s'ouvrent dans un passage annulaire 74 entourant le passage central 76.Furthermore, the first 64 and second 70 fuel supply ports, on the one hand, and the air supply duct or channels 66, on the other hand, open in two coaxial passages 74 and 76, respectively. formed in the inner volume 56. Specifically, the air supply channels 66 open into a central passage 76, and the first and second fuel supply ports open into an annular passage 74 surrounding the passage. central 76.

Selon une caractéristique avantageuse de l'invention, le passage annulaire 74 dans lequel s'ouvrent les orifices d'alimentation en carburant présente une diminution de section 74a dans le sens d'écoulement du carburant afin de former un convergent permettant l'accélération du carburant à sa sortie de ce passage annulaire.According to an advantageous characteristic of the invention, the annular passage 74 into which the fuel supply openings open has a reduction of section 74a in the direction of flow of the fuel in order to form a convergent allowing the acceleration of the fuel. at its exit from this annular passage.

De plus, comme illustré sur les figures 2 à 7, le deuxième étage d'alimentation en carburant peut être décalé axialement par rapport au premier étage, de sorte que les deuxièmes orifices d'alimentation en carburant 70 sont décalés axialement par rapport aux premiers orifices d'alimentation en carburant 64. Ce décalage des étages d'alimentation en carburant peut être prévu lorsque, pour des raisons d'encombrement, il n'est pas possible disposer tous les orifices d'alimentation 64, 70 dans le même plan axial. Dans ce cas, les deuxièmes orifices d'alimentation en carburant 70 ont de préférence des positions angulaires autour de l'axe X-X de l'injecteur décalées par rapport à celles des premiers orifices d'alimentation en carburant 64. De la sorte, la répartition du carburant autour de l'axe de l'injecteur et donc l'homogénéité du mélange air/carburant se trouvent améliorées.Moreover, as illustrated on Figures 2 to 7 , the second fuel supply stage can be axially offset from the first stage, so that the second fuel supply ports 70 are axially offset from the first fuel supply ports 64. This shift of the stages fuel supply can be provided when, for reasons of space, it is not possible to have all the supply ports 64, 70 in the same axial plane. In this case, the second fuel supply ports 70 preferably have angular positions about the axis XX of the injector offset from those of the first fuel supply ports 64. In this way, the distribution fuel around the axis of the injector and thus the homogeneity of the air / fuel mixture are improved.

Les canaux d'alimentation en carburant 62, 72 comportent chacun une première partie, respectivement 62a et 72a, s'étendant parallèlement à l'axe X-X de l'injecteur et raccordée à l'entrée de carburant 60 dans l'injecteur, et une deuxième partie, respectivement 62b et 72b, qui raccorde la première partie à un orifice 64, 70 d'alimentation en carburant. Sur la figure 2, on remarque bien que les premières parties 62a, 72a des canaux d'alimentation en carburant 62, 72 sont au moins en partie confondues. Comme illustré par les figures 4 et 5, dans leurs parties terminales adjacentes aux premiers 64 et deuxièmes 70 orifices d'alimentation en carburant, ces canaux d'alimentation en carburant sont orientés sensiblement tangentiellement par rapport à la paroi du volume interne 56. Ainsi, le carburant s'écoulant dans ces canaux est mis en rotation avant son introduction dans le volume interne ce qui permet d'augmenter sa vitesse d'écoulement et donc de favoriser l'homogénéité du mélange air/carburant.The fuel supply channels 62, 72 each comprise a first part, respectively 62a and 72a, extending parallel to the axis XX of the injector and connected to the fuel inlet 60 in the injector, and a second portion, respectively 62b and 72b, which connects the first portion to a fuel supply port 64, 70. On the figure 2 , we notice that the first parts 62a, 72a of the fuel supply channels 62, 72 are at least partially merged. As illustrated by Figures 4 and 5 , in their terminal portions adjacent to the first 64 and second 70 fuel supply ports, these fuel supply channels are oriented substantially tangentially with respect to the wall of the internal volume 56. Thus, the fuel flowing in these channels is rotated before its introduction into the internal volume which allows to increase its flow rate and thus to promote the homogeneity of the air / fuel mixture.

La disposition du ou des canaux d'alimentation en air 66 est notamment illustrée par les figures 3 et 6. Ces canaux débouchent dans le volume interne 56 dans une direction qui est sensiblement tangentielle par rapport à la paroi du volume interne et qui est inclinée vers l'aval par rapport à un plan normal à l'axe X-X de l'injecteur. Cette disposition particulière améliore également l'homogénéité et la vitesse d'écoulement du mélange air/carburant.The arrangement of the air supply channel (s) 66 is particularly illustrated by the Figures 3 and 6 . These channels open into the internal volume 56 in a direction which is substantially tangential to the wall of the internal volume and which is inclined downstream relative to a plane normal to the axis XX of the injector. This particular arrangement also improves the homogeneity and flow velocity of the air / fuel mixture.

On décrira maintenant les éléments constitutifs du nez d'injecteur ci-dessus détaillé en se référant à la figure 7 qui illustre schématiquement en perspective et en éclaté le nez 54 de l'injecteur de carburant 50.The constituent elements of the injector nose detailed above will now be described with reference to the figure 7 which schematically illustrates in perspective and exploded the nose 54 of the fuel injector 50.

Sur cette figure, on voit que le nez d'injecteur est essentiellement formé de trois parties : une partie arrière 78 dans laquelle sont formés le ou les canaux d'alimentation en air 66, au moins une bague 80 dans laquelle sont formés les premier et deuxième étages d'alimentation en carburant et qui est introduite dans un logement 82 formé à l'extrémité aval de la partie arrière, et une partie avant 84 qui se raccorde à la partie arrière, la bague étant immobilisée axialement entre la partie arrière et la partie avant.In this figure, it can be seen that the injector nose is essentially formed of three parts: a rear part 78 in which the air supply duct or ducts 66 are formed, at least one ring 80 in which the first and second fuel supply stage and which is introduced into a housing 82 formed at the downstream end of the rear portion, and a front portion 84 which connects to the rear portion, the ring being immobilized axially between the rear portion and the front part.

Dans le mode de réalisation illustré par les figures 2 à 7, le nez de l'injecteur comporte, au niveau de la bague 80, deux étages d'alimentation en carburant. Bien entendu, on peut imaginer que le nez de l'injecteur, et plus particulièrement la bague 80, comporte plus de deux étages d'alimentation en carburant de façon à multiplier davantage le nombre de points d'alimentation en carburant dans le volume interne de l'injecteur. Dans ce cas, les étages supplémentaires peuvent être décalés axialement les uns par rapport aux autres afin d'accroître le nombre de points d'alimentation en carburant dans le volume interne de l'injecteur.In the embodiment illustrated by the Figures 2 to 7 , the nose of the injector comprises, at the ring 80, two fuel supply stages. Of course, it is conceivable that the nose of the injector, and more particularly the ring 80, has more than two stages of fuel supply so as to further multiply the number of fuel supply points in the internal volume of the fuel. the injector. In this case, the additional floors can be shifted axially relative to each other to increase the number of fuel supply points in the internal volume of the injector.

D'autres caractéristiques avantageuses du système d'injection selon l'invention sont représentées sur la figure 1. Sur cette figure, on constate qu'au moins un passage pour l'air est aménagé entre la douille 44 et la partie de nez entourée par celle-ci. Ce passage permet de réaliser une purge anti-cokéfaction, c'est à dire qu'il empêche que du carburant ne vienne se cokéfier au niveau du nez de l'injecteur, notamment aux faibles débits de carburant. Ce passage pour l'air peut par exemple être réalisé sous la forme d'une pluralité d'orifices 48 régulièrement répartis autour du nez et débouchant au voisinage de la sortie axiale 58 de celui-ci dans une direction sensiblement parallèle à l'axe X-X de l'injecteur 50. Afin d'accélérer l'écoulement de l'air traversant ces orifices 48, il peut être prévu une diminution de section de ce passage dans le sens d'écoulement de l'air.Other advantageous features of the injection system according to the invention are represented on the figure 1 . In this figure, it is found that at least one passage for air is arranged between the sleeve 44 and the nose portion surrounded by it. This passage makes it possible to carry out an anti-coking purge, that is to say that it prevents fuel from coking at the nose of the injector, especially at low fuel flow rates. This passage for the air can for example be made in the form of a plurality of orifices 48 regularly distributed around the nose and opening in the vicinity of the axial outlet 58 thereof in a direction substantially parallel to the axis XX of the injector 50. In order to accelerate the flow of the air passing through these orifices 48, a reduction in section of this passage in the direction of flow of the air may be provided.

En outre, des trous 25 de passage d'air sont formés dans la paroi 21 du bol 20 afin de réaliser une purge anti-cokéfaction au niveau du bol. Ces trous 25 débouchent dans la chambre de combustion dans une direction qui peut présenter une inclinaison par rapport à l'axe X-X et être tangentielle par rapport à la paroi évasée 21 du bol afin d'éviter tout risque de cokéfaction.In addition, air passage holes 25 are formed in the wall 21 of the bowl 20 to effect an anti-coking purge at the bowl. These holes open into the combustion chamber in a direction which may be tilted with respect to the X-X axis and be tangential to the flared wall 21 of the bowl to avoid any risk of coking.

De même, des trous 26 de passage d'air sont formés dans la paroi en regard 24 de la collerette de bol afin d'alimenter celle-ci, et plus particulièrement le déflecteur annulaire 10, en air. Ces trous 26 débouchent par exemple de façon sensiblement parallèle à l'axe X-X de l'injecteur de sorte que l'air les traversant vient frapper le rebord 23 de la paroi 21 du bol et s'écoule le long du déflecteur annulaire 10.Similarly, air passage holes 26 are formed in the facing wall 24 of the bowl flange to feed it, and more particularly the annular baffle 10, with air. These holes 26 open for example substantially parallel to the X-X axis of the injector so that the air passing through them hits the flange 23 of the wall 21 of the bowl and flows along the annular baffle 10.

Les trous 25, 26 et orifices 48 de passage d'air des différents éléments du système d'injection, ainsi que des fentes d'air 36, 38 respectivement pour les vrilles primaire 32 et secondaire 34 peuvent être répartis selon N secteurs angulaires de 360/N° chacun. Plus précisément, pour chaque secteur angulaire, le bol 20 peut par exemple comporter n trous 25 de passage d'air de formes identiques entre eux (par exemple circulaires, elliptiques, ...) et débouchant parallèlement les uns aux autres. Ce même principe peut être adopté pour les autres trous et fentes de passage d'air. A titre d'exemple, la figure 7 illustre schématiquement, dans un plan P perpendiculaire à l'axe X-X, un exemple de répartition de ces différents passages d'air. Sur cette figure, seuls sont représentés les passages d'air d'un secteur angulaire de 60° ; ils comprennent : trois orifices 48 aménagés entre la douille 44 et la partie de nez entourée par celle-ci, deux fentes d'air 36 pour la vrille primaire, trois fentes d'air 38 pour la vrille secondaire, quatre trous 25 de passage d'air formés dans la paroi 21 du bol, et huit trous 26 de passage d'air formés dans la paroi en regard 24 de la collerette de bol. La répartition de ces différents passages d'air est régulière autour de l'axe X-X. Ils peuvent être réalisés directement en fonderie.The holes 25, 26 and air passage holes 48 of the various elements of the injection system, as well as air slots 36, 38 respectively for the primary 32 and secondary 34 tendrils may be distributed along N 360 angular sectors. / N ° each. More specifically, for each angular sector, the bowl 20 may for example comprise n air passage holes 25 of identical shapes to each other (for example circular, elliptical, ...) and opening out parallel to each other. This same principle can be adopted for other holes and air passage slots. For example, the figure 7 schematically illustrates, in a plane P perpendicular to the axis XX, an example of distribution of these different air passages. In this figure, only the air passages of an angular sector of 60 ° are represented; they comprise: three orifices 48 arranged between the bush 44 and the nose part surrounded by the latter, two air slots 36 for the primary swirler, three air slots 38 for the secondary swirler, four holes 25 for passing through air formed in the wall 21 of the bowl, and eight air passage holes 26 formed in the facing wall 24 of the bowl collar. The distribution of these different air passages is regular around the axis XX. They can be made directly in the foundry.

Claims (18)

  1. A system (2) for injecting an air/fuel mixture into a combustion chamber (4) of a turbomachine, the system having an injector (50) comprising:
    an axial internal volume (56) opening out at one end via an axial outlet (58) for the air/fuel mixture;
    a first fuel feed stage with a plurality of first fuel feed orifices (64) which open out into the internal volume, which are distributed around an axis (X-X) of the injector, and which are connected by fuel feed channels (62) to an inlet (60) for admitting fuel into the injector; and
    at least one air feed channel (66) which opens out into the internal volume and which is connected to an inlet (68) for admitting air into the injector;
    characterized in that the injector further comprises at least one second fuel feed stage with a plurality of second fuel feed orifices (70) which open out into the internal volume, which are distributed around the axis of the injector, and which are connected to said inlet for admitting fuel into the injector via fuel feed channels (72) which coincide at least in part with the fuel feed charnels (62) of said first stage.
  2. A system according to claim 1, characterized in that the first and second fuel feed orifices (64, 70), and the air feed channels (66) open out into two coaxial passages (74, 76) formed in the internal volume.
  3. A system according to claim 2, characterized in that the passage (74) into which the fuel feed orifices (64, 70) open out presents a section that decreases in the fuel flow direction so as to accelerate the flow of fuel in the internal volume.
  4. A system according to claim 2 or claim 3, characterized in that the air feed channel(s) (66) open out into a central passage (76), and the fuel feed orifices (64, 70) open out into an annular passage (74) surrounding the central passage.
  5. A system according to any one of claims 1 to 4, characterized in that the second fuel feed orifices (70) are axially offset from the first fuel feed orifices (64).
  6. A system according to claim 5, characterized in that the second fuel feed orifices (70) occupy angular positions around the axis of the injector that are offset from the positions occupied by the first fuel feed orifices (64).
  7. A system according to any one of claims 1 to 6, characterized in that the terminal portions of the fuel feed channels (62, 72) adjacent to the first and second fuel feed orifices (64, 70) are oriented substantially tangentially relative to the wall of the internal volume (56).
  8. A system according to any one of claims 1 to 7, characterized in that the fuel feed channels (62, 72) comprise respective first portions (62a, 72a) extending parallel to the axis of the injector and connected to the inlet for admitting fuel into the injector, and respective second portions (62b, 72b) connecting the first portions to respective fuel feed orifices (64, 70).
  9. A system according to claim 8, characterized in that the first portions (62a) of the fuel feed channels (62) connected to the first fuel feed orifices (64) and the first portions (72a) of the fuel feed channels (72) connected to the second fuel feed orifices (70) coincide, at least in part.
  10. A system according to any one of claims 1 to 9, characterized in that the air feed channel(s) (66) open out into the internal volume (56) in a direction which is substantially tangential relative to the wall of the internal volume and which is inclined downstream relative to a plane normal to the axis (X-X) of the injector.
  11. A system according to any ane of claims 1 to 10, characterized in that the injector comprises:
    a rear part (78) in which the air feed channel(s) (66) is/are formed;
    at least one ring (80) in which the first and second fuel feed stages are formed and which is introduced in a housing (82) formed at the downstream end of the rear part; and
    a front part (84) connected to the rear part, the ring being prevented from moving axially between the rear part and the front part of the injector.
  12. A system according to any one of claims 1 to 11, characterized in that each fuel feed stage has four fuel feed orifices (64, 70) regularly distributed around the axis (X-X) of the injector.
  13. A system according to any one of claims 1 to 12, characterized in that it further comprises a bushing (44) surrounding at least a portion of the injector (50), a bowl (20) forming a diverging portion for mounting the injection system on an end wall (6) of a combustion chamber, and at least one air swirler (32, 34) interposed between the bushing and the bowl.
  14. A system according to claim 13, characterized in that at least one air passage (48) is provided between the bushing (44) and the portion of the injector surrounded by said bushing.
  15. A system according to claim 13 or claim 14, characterized in that a Venturi (30) is formed between the bowl (20) and the portion of the injector surrounded by the bushing.
  16. A system according to any one of claims 13 to 15, characterized in that it includes two air swirlers, namely a primary swirler (32) and a secondary swirler (34).
  17. A system according to any one of claims 13 to 16, characterized in that air flow holes (25) are formed through the wall (21) of the bowl that forms a diverging portion.
  18. A system according to any one of claims 13 to 17, characterized in that the downstream end of the bowl (20) has a rim (23) which co-operates with a facing wall (24) to define an annular channel-section setback, and air flow holes (26) are formed through said facing wall in order to feed air into said setback.
EP02292866A 2001-11-21 2002-11-19 Multi-stage injection system of an air/fuel mixture in a gas turbine combustion chamber Expired - Lifetime EP1314933B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0115042A FR2832493B1 (en) 2001-11-21 2001-11-21 MULTI-STAGE INJECTION SYSTEM OF AN AIR / FUEL MIXTURE IN A TURBOMACHINE COMBUSTION CHAMBER
FR0115042 2001-11-21

Publications (2)

Publication Number Publication Date
EP1314933A1 EP1314933A1 (en) 2003-05-28
EP1314933B1 true EP1314933B1 (en) 2008-09-17

Family

ID=8869620

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02292866A Expired - Lifetime EP1314933B1 (en) 2001-11-21 2002-11-19 Multi-stage injection system of an air/fuel mixture in a gas turbine combustion chamber

Country Status (6)

Country Link
US (1) US6820425B2 (en)
EP (1) EP1314933B1 (en)
DE (1) DE60228924D1 (en)
ES (1) ES2314022T3 (en)
FR (1) FR2832493B1 (en)
RU (1) RU2293862C2 (en)

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Also Published As

Publication number Publication date
ES2314022T3 (en) 2009-03-16
EP1314933A1 (en) 2003-05-28
DE60228924D1 (en) 2008-10-30
RU2293862C2 (en) 2007-02-20
FR2832493B1 (en) 2004-07-09
US20030131600A1 (en) 2003-07-17
US6820425B2 (en) 2004-11-23
FR2832493A1 (en) 2003-05-23

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