GB2215029A

GB2215029A - Gas turbine engine fuel burner

Info

Publication number: GB2215029A
Application number: GB8802718A
Authority: GB
Inventors: Jeffrey Douglas Willis
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1988-02-06
Filing date: 1988-02-06
Publication date: 1989-09-13
Anticipated expiration: 2008-02-06
Also published as: DE3901232A1; GB2215029B; FR2626938A1; FR2626938B1; JP2636397B2; GB8802718D0; DE3901232C2; JPH01234704A

Abstract

A fuel burner (10) suitable for a gas turbine engine comprises an annular body (11) within which is coaxially located a centre body (22). The centre body (22) is hollow and is provided at its downstream end with an end cap (28), whose peripheral ring portion 29 cooperates with the downstream end of the annular body 11 to define a radial fuel/air mixture outlet (30). Air directed into the interior (33) of the centre body (22) provides transpiration cooling of the end plate centre portion (34) and is also directed via passages (35) to provide an air flow over the radially outer extent (29) of the downstream face of the end cap (28) to provide cooling thereof and prevent the build-up of carbon thereon. <IMAGE>

Description

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2 r,, 111 750 2 9 1 0 GAS TURBINE ENGINE FUEL BURNER This invention -relates to a gas turbine engine fuel burner.

one form of fuel burner suitable for use in a gas turbine engine comprises a generally annular body having an internal surface on to which fuel is sprayed. The fuel flows along the surface to the end of the annular body where both it, and the air flow which operationally passes through the body, are directed in radially outward directions through an outlet defined by the downstream end of the annular body and an end cap mounted in axially spaced apart relationship with the downstream end of the annular body.

It has been found with such fuel burners that there is a tendency for the end cap of the fuel burner to overheat and for carbon to build-up on the peripheral regions of the end plate.

it is an object of the present invention to provide a fuel burner having an -end cap which is less prone to overheating and carbon build-up than has heretofore been the case.

According to the present invention, a fuel burner suitable for a gas turbine engine comprises an annular body, the upstream end of the interior of which is adapted, in operation, to be supplied with a fuel and a flow of air, the downstream -end of said annular body being provided with an end plate which cooperates with said annular body to define a generally -radially directed outlet for all of said fuel directed into said annular body and a portion of the air operationally flowing through said annular body, said end plate comprising a peripheral portion having a generally downstream facing surface and a centre portion, the flowing through remainder of said air flow operationally f said annular body being directed to provide cooling of said end plate centre portion and an air flow over at least the radially outer extent of said downstream surface of said peripheral portion to provide cooling thereof and the inhibition of the formation of carbon thereon.

2 The invention will now be described by way of example with reference to the following drawings in which Figure 1 is a sectioned side view of one embodiment of a fuel-burner in accordance with the present invention.

Figure 2 is a sectioned side view of a further,embodiment of a fuel burner in accordance with the present invention.

With reference to Figure 1 of the drawings a fuel burner suitable for a gas turbine engine Xnot shown) is generally indicated at 10. The fuel burner 10 comprises an annular body 11 which is, in operation, attached to the upstream wall, or head 12 of a conventional gas turbine engine combustion chamber (not shown).

The annular body 11 defines a radially inner annular surface 13 on to the upstream region 14 of which is directed a plurality of jets of fuel which may, for instance be diesel fuel oil, from an axially elongate annular fuel manifold 15. The fuel manifold 15 is of smaller diameter than the annular body 11 and includes an annular chamber 16 which is fed with fuel via a fuel supply passage 17 provided within an arm 18' supporting the manifold 15. The fuel manifold 15 is located coaxially with and upstream of the annular body 11 to the extent that a portion of the downstream end of the fuel manifold 15 extends into the annular -body 11 so that an annular passage 21 is defined between them. A plurality of small nozzles 19 are provided in the fuel manifold 15 to interconnect the annular chamber 16 with the annular gap 21 and thereby operationally define the jets of fuel, which are indicated by the interrupted 1 ines 2-0. The fuel jets 20 therefore pass across the annular passage 21.

The annular body 11 carries a generally Circular cross-section hollow centre body 22 via a plurality of radially extending aerodynamic struts 23. The majority of the centre body 22 is coaxially located within the annular body 11 so that an annular flow path 24 is defined between them. The upstream end 25 of the centre body 22 is of a 1 1 3 smaller diameter than the remainder thereof so as to permit that end 25 to locate coaxially within the downstream end of the fuel manifold 15. The centre body upstream end 25 is of smaller diameter than the fuel manifold 15 so that second annular passage 26 is defined between them which is coaxial with the first annular passage 21.

The upstream end of the fuel burner 10 is, in operation, exposed to a flow of high pressure air delivered by the compressor of the gas turbine engine in which it is mounted. That air flow is divided into three flows by the fuel manifold 15, the annular body 11 and the centre body 22: a first flow through the first radially outer annular passage 21, a second fLow through the second radially inner annular passage 26, and a third flow through an orifice 27 provided in the upstream end 25 of the centre body 22.

The two air flows through the inner and outer passages 21 and 26 combine downst-ream of the fuel manifold (15) to create a minor region of turbulence 28. However such turbulence is localised so that the majority of the air flow along the annular flow path 24 is non-turbulent.

The do-vjnstream-end of the centre body 22 is constituted by an end cap 28. T-the end cap 26 has a peripheral ring-shaped portion 29 which is of generally frusto-conical configuration h.nd cooperates with the downstream end of the annular body 11 to define a generally radially directed annular outlet 30 for the air flow along the annular flow path 24. ' A plurality of vanes 31 extend across almost the whole of the axial extent of the outlet 30 to ensure that the air flow remains non-turbulent in the region of the outlet 30. In the present embodiment, the air flow from the outlet 30 is directed in a slightly upstream direction. it will be appreciated, however, that the actual direction will depend upon the characteristics of the combustion chamber with which the fuel burner 10 is associated.

The fuel directed by the nozzles 19 on to the annular surface 13 flows along that surface 13 and, of course, around the aerodynamic struts 23 in the form of a film as indicated by the interrupted lines 32.

1 4 When that film of fuel reaches the downstream end of the annular body 11, it is atomised by the airflow exhausting from the outlet 30 and mixes with that airf low to place a combustible mixture within the combustion chamber with which the fuel burner 10 is associated.

It will be seen therefore that there is a minimal amount of turbulence within the fuel burner 10, thereby substantially reducing the risk of recirculation and therefore spontaneous combustion occurring within it.

The air flow through the orifice 27 and into the interior 33 of the centre body 22 serves to provide cooling of the centre portion 34 end cap 28, this being a region which in operation is particularly prone to overheating. The endcap, centre portion 34 is formed from a transpiration cooled material of the type described, for example, in UK Patent No. 2049152B.

Some of the air f low into the centre body interior 33 flows through a plurality of radially extending passages 25 provided in the end cap 28. Each of the passages 35 interconnects the centre body interior 33 with the downstream surface of the peripheral ring-shaped portion 29 of the end plate 28. -This ensures that some of the air from the centre body interior 33 f lows over the downstream surface of the end plate portion 29, thereby serving the dual role of providing cooling of the end plate portion 29 and inhibiting the formation of carbon build-up thereon.

in Vigure 2 there is shown a further embodiment of the present invention in which a fuel burner 10a of generally similar configuration to that shown in Figure 1 is provided with a dif ferent form of end cap. Those portions of fuel burner odiment 10a shown in Figure 2 which are common with those with the fuel burner 10 of Figure 1 are provided with common reference numerals.

The end cap 36 of the fuel burner 10a shown in figure 2 is constituted by an imperforate plate 37 which closes the downstream end of the centre body 22 and defines the centre portion 38 of the end cap 36.

Q1 L Immediately upstream of the centre portion 38 of the end cap 36 and in axially spaced apart relationship therewith, there is provided an apertured plate 39. Air flowing into the centre body interior 33 passes through the apertures 40 in the plate 39 to provide impingement cooling of the end cap centre portion 38. The air then flows through a plurality of cadially extending passages 41 provided in the end cap 36. As in the case of the embodiment of f iqure 1 each of the passages 41 interconnects the centre body interior 33 with the downstream surface of the peripheral ring shaped portion 29 of the end plate 36. The ring-shaped portion 29 is thus cooled and carbon is inhibited from forming on its surface.

Although the present invention has been described with reference to full burners 10 and 10a having an end cap centre portion which is cooled by transpiration or impingement cooling, and it will be appreciated that other forms of cooling could be utilised if appropriate.

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Claims

Claims:-

1. A fuel burner suitable for a gas turbine engine comprising an annular body, the upstream end of the interior of which is adapted, in operation, to be supplied with fuel and a f low of air, the downstream end of said annular body being provided with an end plate which cooperates with said annular body to define a generally radially directed outlet for all of said fuel directed into said annular body and a portion of the air operationally flowing through said annular body, said end plate comprising a peripheral portion having a -generally downstream facing surface and a centre portion, the remainder of said air flow operationally flowing t-hrough said annular body being directed to provide cooling of said end plate centre portion, and an air f low over at least the radially outer extent of said downstream surface of said peripheral portion to provide cooling -thereof and the inhibition of the formation of carbon thereon.

2. A fuel burner as claimed in claim 1 wherein said end plate is located at the downstream end of a centre body the maj-ority of which centre body is coaxially located within said annular body and in radially spaced apart relationship therewith.

3. A fuel burner as claimed in claim 2,wherein said centre body is hollow, said remainder of said air flow operationally flowing through said annular body being directed into the interior of said centre body prior to being directed to provide said cooling of said end plate centre portion a-nd said air flow over at least the radially outer extent of the downstream surface of said peripheral portion.

4. A fuel burner as claimed in any are preceding claim wherein said air flow directed to flow over at least the radially outer extent of said downstream surface of said peripheral portion is so directed via a plurality of passages interconnecting the interior of said centre body with the downstream face of said end cap.

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5. A fuel burner as claimed in claim 4 wherein the total extents of said plurality of passages are situated within said end cap.

6. A fuel burner as claimed in any are preceding claim wherein said end plate centre portion is transpiration cooled.

7. A fuel burner a claimed in any are of claims 1-5 wherein said end plate is impingement cooled.

8. A fuel burner as claimed in any are preceding claim wherein said peripheral portion of said end plate is of generally frusto-conical configuration.

9. A fuel burner substantially a hereinbefore described with reference to and as shown in any one of figures 1 and 2 of the accompanying drawings.