GB2411000A

GB2411000A - Guide member for a fuel injection arrangement

Info

Publication number: GB2411000A
Application number: GB0427683A
Authority: GB
Inventors: Allan John Salt; Gary Eadon; Ian James Toon; Andrew Charles Graham
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2004-02-12
Filing date: 2004-12-17
Publication date: 2005-08-17
Also published as: GB0403057D0; GB0427683D0

Abstract

A guide member 62 has a main body 78 and includes a first face 80 and a second face 82. The first and second faces are on opposite sides of the main body, and the first face has an extended directing formation 88. The first face has a first region 84 and a second region 86. A cooling medium is arranged to flow on the second face, and the main body has at least one first flow conduit 92 arranged for a first flow of the cooling medium from the second face to the first region of the first face. The main body also has at least one second flow conduit 96 arranged for a second flow of the cooling medium from the second face to the second region of the first face. The extended directing formation directs the first flow of cooling medium over the first region of the first face. The guide member is suitable for guiding fuel and air in a fuel injection arrangement and the fuel injection arrangement may be incorporated in a gas turbine engine combustor system. Additionally, the fluid flow conduit 92 is arranged by drilling through the main body to a recess 90 formed by the main body and the extended directing formation, and utilising a plastics liner (106 fig 6) within the recess to prevent drilling of the extended directing formation.

Description

241 1 coo Guide Member for a Fuel Injection Arrangement This invention

relates to guide members for fuel injection arrangements. More particularly, but not exclusively, the invention relates to guide members for fuel injection arrangements in combustors of gas turbine engines.

In a fuel injection arrangement, it is necessary to provide a flow of cooling air to prevent a build-up of carbon. However, the cooling air flow does not pass across the whole of the surface to be cooled, and a build-up of carbon can occur in that area. This can be a problem in the event of excessive carbon being shed leading to combustor and turbine damage.

According to one aspect of this invention, there is provided a guide member for guiding fuel and air in a fuel injection arrangement, the guide member comprising a main body having a first face and a second face, the first and second faces are on opposite sides of the main body, the first face having a directing formation extending from the first face, the first face having a first region and a second region, a cooling medium being arranged to flow on the second face, the main body having at least one first flow conduit defined therethrough for a first flow of the cooling medium from the second face to the first region of the first face and the main body having at least one second flow conduit defined therethrough for a second flow of the cooling medium from the second face to the second region of the first face and the directing formation directing the first flow of cooling medium over the first region of the first face.

Conveniently, the cooling medium comprises air.

Preferably fuel and air can flow along the second face.

In one embodiment, the main body comprises a plurality of first flow conduits for the first flow of the cooling medium from the second face to said first region of the first face.

Preferably, the main body comprises a plurality of second flow conduits for the second flow of the cooling medium from the second surface to said second region of the first face.

The main body may have a main axis and the, or each, flow conduit may extend at an angle of between 10 and 80 to the main axis, preferably between 30 and 60 to the main axis, more preferably between 40 and 50 to the main axis and most preferably at substantially 45 to the main axis. The or each, flow conduits may be substantially tangential to the main body.

The directing formation may define a recess with said first region of the first face. Preferably, the recess is annular in configuration. The recess is preferably a blind recess having a blind wall and the at least one first conduit is preferably defined at the blind wall of the recess. The blind wall is preferably annular.

The main body may have an annular configuration, and may comprise a cylindrical portion and a radially outwardly extending flared portion. Desirably, the directing formation is generally annular in configuration having a radially outwardly extending flared member.

Preferably, the recess is defined between said flared portion and said flared member.

According to another aspect of this invention, there is provided a method of forming a fluid flow conduit in a guide member as described above, the method comprising arranging a drilling apparatus in a drilling position relative to the guide member, wherein the drilling apparatus is arranged to drill through the main body to the recess, and the method further involves arranging a plastics liner within the recess to prevent drilling of the directing formation.

Preferably, the liner is formed of a plastics material such as inert plastics material. The plastics material may be a polytetrafluoroethylene. Preferably, the drilling apparatus has a head and a drilling tip and the apparatus is angled sufficiently to allow the head of the apparatus to be clear of the main body.

An embodiment of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a schematic cross-sectional view of a combustor assembly associated with a gas turbine engine; Fig. 2 is a schematic cross-sectional view of a fuel injection assembly; Fig. 3 is a schematic cross-sectional view of the region marked "A" in Fig. 2; Fig.4 is an end view along the line IV of the guide member of the fuel injection arrangement shown in Fig. 2; Fig. 5 is a view similar to Fig. 3 showing a liner used during formation of the flow conduits; Fig. 6 is a schematic diagrammatic view showing formation of a fluid flow conduit.

Referring to Fig. 1, there is shown a combustor arrangement 15 for a gas turbine engine shown schematically at 10. The operation of the combustor arrangement 15 combusts fuel in compressed air in order to create the required power.

In order to provide combustion, it is necessary to mix air flows with fuel in appropriate proportions. This fuel can be a hydro-carbon gas and, in connection with oil and natural gas production off-shore platforms, operation of a gas turbine engine as an electricity generator or pump can be achieved by drawing gas from well production. However, during fabrication and construction of the production platform, a supply of gas is not available and so operation of the turbine engine will require an alternative fuel source.

Similarly, engines used for on-shore power generation normally use natural gas fuel for emission and economic reasons. The preferred embodiment of the present invention utilises a diesel or kerosene liquid as an alternative fuel. This alternative fuel can also be used during period of production platform maintenance and as an emergency back-up fuel supply.

In Fig. 1 there is shown a gas turbine engine combustor arrangement 15, which comprises a combustor 20 and an injection assembly 16. The combustor 20 is supplied with fuel and air in order to provide propulsive combustion for the engine 10.

Air is supplied via combustor inlets 22 in the direction of arrows 24 in order to become mixed with fuel presented through an injection arrangement 26. The injection arrangement 26 can present a gas fuel along a conduit 27 in the direction of arrows 28 or liquid/diesel fuel through an injection conduit 30.

The diesel fuel is presented in the direction of arrow 32 whilst air for vaporising or atomising the liquid fuel is presented in the direction of arrow 34. It will be appreciated that it is important to atomise or vaporise the liquid fuel in order to create droplets appropriate for combustion within the combustor 20. In such circumstances it is important to provide adequate and proportionate liquid fuel and air flow rates and present these two flows at appropriate angles to each other in order to create the desired liquid fuel droplets. The present invention particularly relates to an outlet 36 of the fuel injection arrangement 26.

Fig. 2 is a more detailed but still schematic representation of the fuel injection arrangement 26. The arrangement 26 comprises liquid fuel injection jets 38 which deliver liquid fuel to an output end region 36, of the fuel injection arrangement 26.

The gas fuel is presented in the direction of arrow 28 through a gas fuel conduit to a gas manifold 40 whereupon the gas fuel passes in the direction of arrow 42 through a pathway 44 for presentation through gas diffusion apertures 46 into a combustor 20. This gas fuel is typically provided upon a production platform by appropriate bleed diversion of fuel gas from the production of natural gas or oil.

Gas acquired will be used for operation of a turbine engine using a fuel injection assembly in accordance with the present invention. During periods when such gas is not available, a liquid fuel such as diesel or kerosene will be used in order to provide combustion and therefore provide power to the turbine engine generator or prime mover for pump assemblies etc. Liquid fuel is presented in the direction of arrow 32 through a liquid fuel feed tube 48. This liquid fuel congregates in a liquid fuel manifold 50 and subsequently passes in the direction of arrow 52 through fuel pathway 54 to the liquid fuel jets 38, the fuel pathway 54 and the liquid fuel jets 38 joining the injection conduit.

Air for the present fuel injection arrangement passes in the direction of arrow 34 through an injection pathway 56 towards an outlet 58. A snubber element 60 is provided in order to ensure appropriate spacing for the pathway 56.

It is by size and configurational relationships between the liquid fuel flowing through the jets 38 and the airflow 34 through pathways 56 that appropriate fuel droplets are achieved for combustion, both at low liquid fuel flow rates upon ignition and at a higher liquid fuel flow rates necessary for full load turbine operation. It will also be understood that the manner and presentation of the outlet 58 within the combustor 20 will be highly determinant with respect to obtaining appropriate mixing of the liquid fuel with air for combustion. In such circumstances, typically as schematically illustrated, bottom peripheral edges of a trumpet shaped central guide member 62, have a shape similar to the head of a trumpet.

The bottom peripheral edges subtend an angle 63 of about 115 . However, it will be understood that the particular angle 63 will depend upon the internal aerodynamics of the combustor.

Generally, the guide member 62 guides the air and fuel to the outlet 58 and has a hollow centre through which further air flows in the direction of arrowhead 68.

Referring to Fig. 3, there is shown a close-up of the fuel-injection arrangement at the region marked A in Fig.2, from which it can be seen that fuel flows along the pathway 54, as indicated by the arrow 52. The fuel passes through the jet 38 into the injection pathway 56. Air, as shown by the arrow 34 passes along the injection pathway 56 and mixes with the fuel. The fuel/air mixture passes out of the injection pathway 56 via the outlet 58.

The injection pathway 56 is defined by the guide member 62 which comprises main body 78 having a first face 80, and a second face 82 opposite the first face 80. The first face 80 comprises a first region 84 and a second region 86.

An annular air directing formation 88 having a trumpet like configuration like the head of a trumpet is provided on the first face 80 and extends therefrom. The air directing formation 88 divides the first face 80 into the first region 84 and a second region 86. An annular recess is defined between the formation 88 and the first region 84. A plurality of first air flow conduits 92 extend through the guide member 62 from the injection pathway 56 to the recess 90. In Fig 3, the first region 84 extends from the lower end of the guide member 62 to the air flow conduits 92. The second region extends from the lower end of the air directing formation 88 upwardly. The air directing formation 88 has an inner face 94 opposite the first region 84.

The first air flow conduits 92 are arranged in an annular array around the formation 88. Air passing through the first air flow conduits 92, shown by the arrow 93, impinges on the inner face 94 of the air directing formation 88 and flows across the first region 84 of the first face 80. After the air jets 93 impinge on the inner face 94, the air jets 93 pass from the inner face 94 with a part tangential component relative to the periphery of the inner face 94. As a result the air jets 93 passing from the inner face 94 is convergent on the first region 84.

Hence, the air flows onto the first region 84 of the first face 80 and helps to reduce/prevent carbon formation on the first region 84. Air flowing radially from the periphery of the inner face 94 would not impinge upon the first face 84. The impingement of the air jets 93 on the inner face 94 of the air directing formation 88, in the preferred embodiment, helps prevent/reduce carbon formation on the second region 86 of the first face 80.

A plurality of second air flow conduits 96 are provided through the guide member 62 from the second face 82 to the first face 80, to provide a flow of air from the injection pathway 56 to the second region 86 of the first face 80 as shown by the arrows 97. Thus, as shown by the arrows 93 and 97, cooling flows of air pass across the first and second regions 84, 86, of the first face 80.

The second face 82 of the guide member 62 is shaped to guide the air and fuel in the pathway 56 to the outlet 58.

Referring to Fig. 4, there is shown an end view of the guide member 62 showing the first face 80 and the direction of flow of air across the first region 84 of the first face 80. Fig. 4 also shows the first fluid flow conduits 92 (shown in broken lines), and the angle made by the first fluid flow conduits 92 through the guide member 62.

As can be seen, the first fluid flow conduits 92 are angled relative to the main axis X and extend tangentially to the main body, thereby providing a swirling flow across the first region 84A of the first face 80. Also, the second fluid flow conduits 96 not shown in Fig. 4 are similarly angled relative to the main axis and provide a swirling flow of air across the second region 86 of the first face 80 of the guide member 62.

Fig. 4 also shows the flow of the fuel/air mixture designated by the number 98, as the mixture flows out of the outlet 58. As can be seen, this flow 98 is also approximately tangential to the outlet 58.

Referring to Figs. 5 and 6, there is shown two stages in a method of forming the first fluid flow conduits by suitable laser drilling apparatus 100, comprising a head 102 and a laser drilling part 104. In the first of these stages, shown in Fig. 5 an annular insert 106 is inserted into the recess 90 for reasons that are explained below.

In the second of these two stages shown in Fig. 6, the drilling apparatus 100 drills through the guide member 62 from the second face 82 to the first face 80. In order to do this, the drilling apparatus 100 is angled relative to the main axis X of the guide member 62 so that the head 102 of the drilling apparatus 100 is clear of the guide member 62. The angle that the drilling apparatus 102 makes to the main axis X is in the region of about 45 .

In order to prevent the laser drilling apparatus 100 drilling through the directing formation 88, the annular insert 106 is provided in the recess 90 defined between the directing formation 88 and first region 84 of the first surface 80. The insert 106 is formed of a suitable inert plastics material such as polytetrafluoroethylene, which is resistant to the effects of laser drilling.

For the drilling to take place, the guide member 62 is arranged on a rotatable platform 110, which is incrementally rotated about the axis X by a predetermined amount for each first air flow conduit 92 to be drilled.

There is thus described an effective arrangement whereby the flow of cooling air across the components of a fuel injector are maintained to prevent the build-up of carbon.

Various modifications can be made without defining the scope of the invention, for example the number of first air flow conduits 92 could be altered.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims 1. A guide member for guiding fuel and air in a fuel injection

arrangement, the guide member comprising a main body having a first face and a second face, the first and second faces are on opposite sides of the main body, the first face having a directing formation extending from the first face, the first face having a first region and a second region, a cooling medium being arranged to flow on the second face, the main body having at least one first flow conduit defined therethrough for a first flow of the cooling medium from the second face to the first region of the first face and the main body having at least one second flow conduit defined therethrough for a second flow of the cooling medium from the second face to the second region of the first face and the directing formation directing the first flow of cooling medium over the first region of the first face.
2. A guide member according to Claim 1 wherein the cooling medium comprises air.
3. A guide member according to Claim 1 or claim 2 wherein the main body comprises a plurality of first flow conduits for the first flow of the cooling medium from the second face to said first region of the first face.
4. A guide member according to Claim 1, Claim 2, or Claim 3 wherein the main body comprises a plurality of second flow conduits for the second flow of the cooling medium from the second surface to said second region of the first face.
5. A guide member according to any of Claims 1 to 4 wherein the main body has a main axis and the, or each, flow conduit extends at an angle of between 10 and 80 to the main axis.
6. A guide member according to Claims 5 wherein the, or each flow conduit extends at an angle of between 30 and 60 to the main axis.
7. A guide member according to Claim 5 or Claim 6 wherein the, or each, flow conduit extends at an angle of between 40 and 50 to the main axis.
8. A guide member according to Claim 5, Claim 6 or Claim 7 wherein the, or each, flow conduit extends at an angle of substantially 45 to the main axis.
9. A guide member according to any of Claims 5 to 8 wherein the, or each, flow conduits are substantially tangential to the main body.
10. A guide member according to any preceding claim wherein the directing formation defines a recess with said first region of the first face.
11. A guide member according to Claim 10 wherein the recess is annular in configuration, and the recess is a blind recess having an annular blind wall and the at least one first conduit is defined at the blind wall of the recess.
12. A guide member according to Claim 11 wherein the main body has an annular configuration, and comprises a cylindrical portion, and a radially outwardly extending flared portion, and the directing formation is generally annular in configuration having a radially outwardly extending flared member.
13. A guide member according to Claim 12 wherein the recess is defined between said flared portion and said flared member.
14. A fuel injection arrangement comprising a liquid fuel delivery assembly incorporating a guide member according to any preceding claim.
15. A combustor for a gas turbine engine incorporating a fuel injection arrangement according to claim 14.
16. A gas turbine engine incorporating a combustor according to Claim 15.
17. A method of forming a fluid flow conduit in a guide member, the method comprising arranging a drilling apparatus in a drilling position relative to the guide member, wherein the drilling apparatus is arranged to drill through the main body to the recess, and the method further involves arranging a plastics liner within the recess to prevent drilling of the directing formation.
18. A method according to Claim 17 wherein the liner is formed of a plastics material.
19. A method according to Claim 18 wherein the liner comprises polytetrafluoroethylene.
20. A method according to Claim 17 or 18 wherein the drilling apparatus has a head and a drilling tip and the apparatus is angled sufficiently to allow the head of the apparatus to be clear of the main body.
21. A guide member substantially as herein described with reference to Figs 3 to 6 of the accompanying drawing.
22. A fuel injection arrangement substantially as herein described with reference to Figs. 2 to 6 of the accompanying drawings.
23. A combustor substantially as herein described with reference to the accompanying drawings.
24. A method substantially as herein described with reference to Figs. 5 and 6 of the accompanying drawings.