FR2525692A1 - FUEL INJECTOR FOR GAS TURBINE ENGINES - Google Patents

Abstract

THE INVENTION RELATES TO A FUEL INJECTOR AGENCY IN A COMBUSTION CHAMBER TO PRODUCE TWO AXIALLY ADJACENT AND OPPOSITE RECIRCULATIONS, WHERE THE FUEL AIR RATIO ARE ABOUT 81 IN THE UPSTREAM VIRGIN AND ABOUT 251 DOWNWARD IN THE VIRGIN. ACCORDING TO THE INVENTION, THE AIRFUEL MIXTURE IS PROVIDED TO BE EVACUATED FURTHER UPSTREAM SO THAT ALL THE MIXTURE FLOWS INTO THE UPSTREAM VARIETY, FORMING A DEVIATION LEVER 140 FOR THE AIR COMING FROM THE HOOD 118 AND A RING OF ' STRENGTHENING 142. THE INVENTION MAKES PARTICULARLY REDUCING NOX EMISSIONS AND IMPROVING THE BURNING EFFICIENCY AT IDLE AND THE LOW AIRFUEL EXTINGUISHING RATIO.

Description

FUEL INJECTOR FOR MOTORS

A GAS TURBINE

  The present invention relates to injectors of

  fuel for gas turbine engines and it is a development

  of the type of the fuel injector which is described in

  British Patent Application No. 1427146.

  In this description is indicated an injector of

  fuel having a central duct receiving fuel and air flows, a deflector member disposed adjacent to the downstream end of the duct, which together with the end of the duct forms a radially directed annular outlet for the mixture fuel and air, the tube, and a cover surrounding the central duct forming an outer annular sheath in which the air flows and is discharged from the central duct, upstream of the annular outlet This type of injector fuel, with the combustion chamber in

  which it is placed, is intended to produce two

  adjacent toroidal and opposite directions, the one upstream of which must be rich in fuel and

  the one located furthest downstream must be low in fuel.

  In order to reduce N Ox emissions, the air ratios

  fuel must be of the order of 8/1 in the tour-

  upstream and 25/1 in the downstream vorticity.

  It has been found in practice that

  fuel in both vortices were not always as required The upstream vortex tends to be less fuel-rich and the downstream vortex tends

  to be less fuel-poor, indicating a migra-

  between vortices or a distribution

  disproportionate fuel from the injector in the

  ridges. The arrangement shown in British Patent No. 1427146 was intended to ensure that all fuel from the injector flows into the upstream vortex, the downstream vortex receiving any unburned and / or partially burned fuel from the upstream vortex. now considers that a portion of the upstream fuel injector fuel flows directly into the downstream vortex, thereby weakening the mixture in the upstream vortex and enriching the mixture in the downstream vortex. Such poor distribution has adverse effects on N Ox emissions, combustion efficiency * and low ratio of extinguishing air to fuel. The object of the present invention is to provide an improved form of the type of fuel injector. fuel indicated in British Patent No. 1427146 where the air-to-fuel ratios in both vortices can be

controlled more precisely.

  Similarly, the deflector member at the end of the central sheath has been found to have an unnecessarily complex and costly shape. Thus, the present invention seeks a form

  simpler and less expensive deflector member.

  Accordingly, the present invention relates to a fuel injector for a gas turbine engine arranged to inject air and fuel into a fuel chamber.

  combustion, comprising a central sheath having

  open upstream and downstream, a deflector member placed adjacent to the end of the central duct located downstream, the deflector member and said downstream end together forming an outwardly directed annular outlet, and a cover member at least partially surrounding the central sheath to form an annular sheath, the central sheath and the annular sheath being arranged to receive an air flow of the air compressor or -st placed the fuel injector, the central sheath being also arranged to receive fuel flow from a fuel nozzle, the outwardly directed annular outlet converging all around its circumference and terminating in a discharge opening directed both outwardly and upstream to inject substantially all the air / fuel mixture leaving the discharge opening in a toroidal vortex amcen in the combustion chamber, a seco nd whirlpool toro Idal downstream

  being also formed in the combustion chamber close to

  of the vortex upstream and in a direction opposite to that

this.

3 2525692

  The fuel injection may also have a lip at the end of the central duct located downstream, with

  the deflector member defines the discharge opening

  which also serves to deflect air from the annular sheath.

  far off the air / fuel mixture leaving the discharge opening. The central duct may also have a throttling ring at its upstream end to reduce the

  moment of air / fuel mixture in the central duct.

  When the fuel injector is placed in a

  combustion chamber, the combustion chamber preferably

  a flow into the wall to form an air flow in the upstream and downstream vortices and the fuel discharge opening is directed to an upstream point

  from the air inlet, in the vortex located upstream.

  Other features and advantages of the invention

  will emerge more clearly from reading the description

  which will follow of an exemplary embodiment, given by way of indication but in no way limiting, with reference to the accompanying drawings in which: FIG. 1 is an illustration of the fuel injector and the combustion chamber shown in the British patent above mentioned; Figure 2 is a detailed view of a portion of the central duct and deflector member of the fuel injector shown in Figure 1; Figure 3 is a schematic illustration of a gas turbine engine incorporating a form of a fuel injector according to the present invention; Figure 4 is an elevational view, on an enlarged scale, of a portion of the combustion chamber, and the fuel injector of Figure 1 according to the present invention; Figure 5 is an elevational view of the fuel injector of Figure 4, on an enlarged scale; and FIG. 6 is a detailed view of an inlet ring

  of the combustion chamber of Figure 4.

  Referring to FIGS. 1 and 2, an injector

4 2525692

  fuel 10 has a central duct 12 arranged to receive fuel from a nozzle 14 and the air compressor of the engine, a deflector member 16 and an outer cover 18 with which the

  central duct forms an annular passage of air.

  The central duct downstream, with the deflector member 16, forms an outlet 22 directed radially for the air / fuel mixture, towards a combustion chamber 24.

  in which is the fuel injector.

  An air / fuel mixture comes out radially to create

  a toroidal vortex 26 upstream which is lit by ai.

  igniter (not shown) and the fuel air / fuel mixture

  The flow is entrained in a downstream vortex 28 which is generated in part by the flow of the injector 16 and partly by the air of di which enters the chamber.

combustion by openings 30.

  As can be seen in more detail in Figure 2, the end - a ga L 12 downstream has a lip 32 directed to 'grie 7 to force all the go Velette r .. * burar F > Y o 'a groin re fo rd in coul:', o f the o ni "v :: ctaer 16 a Muae 'i: l? % -: fs 12 _fs l amh c've (: the

surface u r-

  mient cc% v-, e d e L e e: carbura e, extended radi is reduced and-

  is rounds, Icrt the Pxté, and nasse towards d '' e -3 nru-

  Converging Wave 36 Had: Be Yet Turned By = The Bnte 36: Section? i in su ic A and B Ell of a to: ur L-cc> -de a converg e 1 e to the opening annulaiúa 22 o o the mixture the / -fuel is emitted in a direction substantially radially relative to the forward-to-back direction of the engine and the fuel injector The outer portions of the deflector member 16 are configured to give the mixture

  which has an impact on them, a component of

  radially outwardly which, with the downstream moment of the remaining flow, i.e., of the annular sheath 20, forces the outflow 22 to

be substantially radial.

  The opening 22 is defined by a lip 38 on the sheath 12 and is an annular opening whose plane is substantially perpendicular to the longitudinal axis of the motor. The arrangement of the outlet 22 helps to ensure that

  the flow will emanate radially from the fuel injector

rant, outward.

  It can be noted that a considerable effort is imposed on

  the arrangement of the output 22, the relative convergent

  complex complex leading up to the exit and the need for the air / fuel mixture to exit in a purely radial direction. Experience has shown that the arrangement shown in FIGS. 1 and 2 does not offer completely satisfactory conditions for combustion. In particular, the air / fuel ratios in the two vortices can become, undesirably, less fuel-rich.

  and less fuel-poor, respectively in the

  Ridges upstream and downstream Similarly, the inner surface of the deflector member 16 and the end of the central sheath 12

  that define the shape of the exit passage are useless-

  difficult and expensive to produce.

  Referring to Figures 3, 4, 5 and 6 of the

  correspondents have received reference numbers

  1 and 2, with the exception of the prefix 1, a fuel injector 110 is placed in a chamber of

  combustion 124 of a gas turbine engine 100.

  The fuel injector has a central duct 112, a nozzle 114, a deflector member 116, an outer cover 118 and an annular sheath 120 to improve the manufacture of the deflector member 116 in comparison with the deflector member 16 which was expensive and difficult, not only without impairing its performance but also by improving its performance, the deflector 116 is largely formed of a

  number of flat surfaces merging with their

  In particular, the shape of the convergent passage leading to

  opening 122 is formed of two circular surfaces.

  lair and flat 122a and 122b which are at an angle obtuated one

  relative to each other, and which merge at their junction.

  Similarly, the outer surface of the deflector member consists of flat surfaces 122c and 112d, all being made for ease of manufacture At its downstream end, the central sheath has a lip 140 with which the deflector member 116 forms an evacuation opening 122 which faces towards

  the outside in the upstream direction The lip 140 also serves

  to divert the air from the annular sheath 120 away from the air / fuel mixture leaving the opening 122, and in a

whirlpool 126 located upstream.

  A throttling ring 142 is placed at the end of the central duct upstream to reduce the moment of the

  air / fuel mixture flowing through the central duct

  trale, which helps to encourage substantially all the air / fuel mixture and in particular the fuel component to flow directly into the vortex 126 upstream The wall of the combustion chamber 124 has an air inlet 130

  which corresponds to entry 30 but whose form is different

  As can be seen in more detail in FIG. 6, the air inlet 130 has the shape of a cooling ring and has a series of openings 130 'facing upstream, and a group of 130 b turn openings downstream A series of central openings 130c can also be provided to allow a flow of air to cool

  the part of the ring that protrudes the most

  The arrangement of the fuel injector 11 and the

  combustion chamber 134 has an important characteristic

  which is the arrangement of the discharge opening 122 and the air inlet 130. In order for the arrangement to work properly, the discharge opening of the fuel injector must be directed to a point situated in upstream

  openings 130a of the air intake In use the injection

  fuel chamber and the combustion chamber receive an air flow from the engine compressor 100, the fuel injector

  fuel also receiving fuel from fuel 114.

  An air / fuel mixture is discharged through the upstream opening 122 into an upstream vortex 126. Substantially all of the air / fuel mixture, particularly the fuel component, passes directly into this vortex. the fuel in the downstream vortex 128 is received either in unburned or partially burned form, from the upstream vortex The upstream vortex also receives air from the annular sheath 120 and inputs 130a which assist between The lip 132 acts as a deflector for the air leaving the annular sheath 120 stabilizing this flow, encouraging it to enter the vortex upstream and preventing the flow from impacting the air / fuel mixture. 122 opening on any harmful extent The throttling ring 134 reduces the moment of the air / fuel mixture in the central sheath so a purely radial moment of the mela The arrangement allows two air-fuel mixtures to enter the vortex 126 upstream. This arrangement allows two recirculations axially arranged in an opposite direction, where the air / fuel ratio in the upstream vortex is rich. in fuel at a value of about 8/1 and the air / fuel ratio in the whirlpool

  downstream is low in fuel at a value of about 25/1.

  The arrangement has the effect of reducing N Ox emissions by a factor of 1/3 to a total fuel air ratio of 55/1, compared to the arrangement shown in British Patent No. 1427146. same, the idle combustion efficiency is improved by 6% and the air poor ratio

  fuel extinction is increased by a factor of 3.

  Most of the improvement is thought to come from the

  the fitness of the deflector, while the improvement

  remaining improvement is more or less regularly divided

  between the lip 140 and the throttling ring 142.

'5692

Claims (4)

  1 fuel injector for a gas turbine engine arranged for injecting air and fuel into a combustion chamber, characterized in that it comprises a central duct (112) having open ends upstream and downstream, an element baffle (116) disposed adjacent to the end of the downstream central duct, the baffle member and said downstream end together forming an outwardly directed annular outlet, and a bonnet member (118) at least partially surrounding the central gut to form an annular sheath (120), the central sheath and the annular sheath being arranged to receive an air flow from the compressor of the engine where the fuel injector is placed the central sheath also being arranged to receive a flow fuel of a fuel nozzle, the outwardly directed annular sorrace converging t0; turn of its circumference and ending in an open-lirr of é- (ution) (122) directed both outside and - rs the to inject the Yhlement the italir U - '-ne li liia outgoing aperture evacuated, 1 of oldal in am''126) in the chai, A downstream 12 and equal to: -as -h, at oxirz; upstream and in 7 se eose to that   2 Fuel injector according to the revision:? * R, character; The next one is grown to the former one hundred g sheath   and the extra-mi: the gold difier Definitories loui -   evacuation, the lip also serving, air leaving the annular shaft.   A fuel inoculator according to claim 1, characterized in that the central groove has a flow restrictor (142) located adjacent its upstream end to reduce the moment of the air / fuel mixture in the central sheath. 4 fuel injector according to claim 1, characterized in that the face of the deflector member on 9 2525692   which impacts the air / fuel mixture from the central duct, comprises at least two flat surfaces (122a, 122b, 122c, 122d) inclined at an angle of more than 900 to one   relative to each other, and which merge at their junction.