US3498059A - Burner,e.g.,for a gas turbine engine combustion chamber - Google Patents

Description

' March 3, 11970 KGRADON EI'AL BURNER, E.G. FOR A GAS TURBINE ENGINE COMBUSTION CHAMBER Filed Feb. 12, 1968 3 Sheets-Sheet 1 I nvcnlom WW W I M y Aumm March 3, 1970 Y K. GRADON arm. 9 3,498,059

. BURNER, E.G. FOR A GAS TURBINE ENGINE COMBUSTION CHAMBER Filed Feb. 12, 1968 3 Sheets-Sheet 2 M Inventors Attorneys United States Patent 3,498,059 BURNER, E.G., FOR A GAS TURBINE ENGINE COMBUSTION CHAMBER Keith Gradon and Richard Alfred Harvey, Derby, England, assignors to Rolls-Royce Limited, Derby, England, a British company Filed Feb. 12, 1968, Ser. No. 704,803 Claims priority, application Great Britain, Mar. 20, 1967, 13,054/ 67 Int. Cl. F02c 3/00; F23d 11/24 US. Cl. 6039.74 7 Claims ABSTRACT OF THE DISCLOSURE A burner has a jet orifice, a first conduit for supplying the jet orifice with an annular vortex flow of fuel, and a second conduit for supplying air liquid fuel to a hollow central region of the annular vortex to reduce the passage of combustion gases upstream through the jet orifice.

This invention concerns a burner e.g. for a gas turbine engine combustion chamber.

According to the present invention, there is provided a burner having a jet orifice, first conduit means for supplying the jet orifice with an annular vortex flow of fuel, and second conduit means for supplying a fluid to a hollow central region of the said annular vortex flow to reduce or prevent the passage of combustion gases upstream through the jet orifice.

Such combustion gases are liable to entrain carbon particles therewith, and the invention thus reduces the risk of the burner becoming carboned up.

Thus the second conduit means may communicate, at a point substantially upstream of the jet orifice, with the first conduit means to receive a supply of fuel from the latter.

The first conduit means may comprise a fuel chamber,

adapted to be supplied with fuel, a fuel feed annulus, a passage or passages which lead from the fuel chamber to the fuel feed annulus, an axially extending duct leading to the jet orifice, and tangential swirl slots leading tangentially from the fuel feed annulus to the axially extending duct, the said annular vortex flow passing through the axially extending duct.

The said axially extending duct may be annular, the second conduit means communicating with either the said fuel chamber or with the said annular axially extending duct.

The said axially extending duct may have a frustoconical portion at its downstream end, the said second conduit means supplyin fuel to the centre of the said frusto-conical portion.

In an alternative arrangement, the second conduit means are formed to lead air from the exterior of the burner to the said hollow central region. In this case, the second conduit means may lead the said air to the upstream end of the axially extending duct.

The said jet orifice is preferably a pilot jet orifice which is disposed centrally of an annular main jet orifice, third conduit means being provided for supplying the main jet orifice with an annular vortex flow of fuel.

The invention also comprises a gas turbine engine combustion chamber provided with at least one burner as set forth above.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which:

FIGURE 1 is a diagrammatic view, partly in section, of a gas turbine engine having a combustion chamber provided with burners in accordance with the present invention, and

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In FIGURE 1 there is shown a gas turbine engine 10 having an engine casing 11 within which there are disposed, in flow series, a compressor 12, an annular combustion chamber 13 (or an annular array of separate combustion chambers) and a turbine 14 which drives the compressor 12.

The combustion chamber 13 is provided with burners 15 which are supplied with fuel (from a source not shown) through pipes 16. Each of the burners 15 may be formed either as shown in FIGURE 2 or as shown in FIGURE 3.

In the FIGURE 2 embodiment, each of the burners 15 has a centrally disposed conduit 20 formed in a block 21, the conduit 20 being adapted to be supplied with a flow of pilot fuel. The conduit 20 extends to a fuel chamber 22 which is formed in a distance piece 23. The fuel chamber 22 communicates via a plurality of angularly spaced apart radially outwardly inclined passages 24 (or via an annular frusto-conical passage 24) with a fuel feed annulus 25 which is disposed radially outwardly of the fuel chamber 22. A plurality of angularly spaced apart tangential swirl slots 26 lead tangentially from and radially inwardly from the fuel feed annulus 25 to an annular axially extending duct 27. The duct 27 is formed between a cylindrical member 30, whose downstream end is provided with a pilot jet orifice 31, and a sleeve member 32 which is disposed radially inwardly of the cylindrical member 30. The arrangement is thus such that an annular vortex flow of pilot fuel passes through the duct 27 to the pilot jet orifice 31. The downstream end of the sleeve member 32 is disposed upstream of the pilot jet orifice 31 with the result that, at the downstream end of the cylindrical member 30 and within the pilot jet orifice 31, the said vortex flow of pilot fuel has a hollow central region radially inwardly thereof.

The sleeve 32 extends from a central portion 33 of the distance piece 23. Alternatively, the portion 33 could of course be separate from the distance piece 23 and could be arranged to define an annular passage 24 therewith.

The sleeve 32 has an axially extending bore 34 which forms a conduit whose upstream end communicates with the fuel chamber 22.

The downstream end of the duct 27 has a frusto-conical portion 35, the downstream end of the bore 34 communicating with the said portion 35 by way of a hole 36 through an end wall 37 of the sleeve 32.

The fuel which passes through the bore 34 and hole 36 thus fills at least part of the hollow central region within the annular vortex flow of fuel supplied to the pilot jet orifice 31. Accordingly, the fuel through the bore 34 reduces or prevents the passage of combustion gases upstream through the pilot jet orifice 31. This is desirable because if the combustion gases are allowed to pass upstream through the pilot jet orifice 31 they may carry carbon therewith which will be entrained by the fuel and can cause carboning up of the burner.

Furthermore, the fiow of fuel through the bore 34 modifies the spray formed at the pilot jet orifice 31. Thus, if it were not for the flow of fuel through the bore 34, the spray formed by the frusto-conical portion 35 would have an outside angle which was only very slightly greater than its inside angle. The flow of fuel through the bore 34, however, reduces the said inside angle and thus increases the difference between the latter and the said outside angle. This produces a better distribution of the fuel, and a better mixing of the fuel with the air.

The hole 36, instead of communicating via the bore 34 with the fuel chamber 22, could alternatively communL cate with the duct 27 to receive fuel therefrom, there being 3 in this case a wall between the upstream end of the bore 34 and the fuel chamber 22.

The pilot jet orifice 31 is disposed centrally of an annular main jet orifice 40.

The block 21 has an annular conduit 41 therein through which passes a main flow of fuel, the annular conduit 41, which is arranged concentrically about the conduit 20, leading to an annular conduit 42 in the distance piece 23. The annular conduit 42 leads to an annular fuel chamber 43 which is formed mainly in the distance piece 23 and partly in a radially extending flange portion 44 of the cylindrical member 30. The portion 44 has a plurality of angularly spaced apart passages 45 therethrough whose upstream ends communicate with the annular fuel chamber 43 and whose downstream ends communicate with a fuel feed annulus 46.

A plurality of angularly spaced apart tangential swirl slots 47 extend tangentially from the fuel feed annulus 46 and lead radially inwardly to and extend tangentially of an axially extending duct 50 which is disposed concentrically about the duct 27. The arrangement is such that an annular vortex flow of fuel passes downstream through the duct 50 so as to be supplied to the main jet orifice 40.

Although, however, there will be a hollow central region disposed inwardly of the annular vortex flow of fuel through the main jet orifice 40, combustion gases will not be able to pass upstream therethrough since this hollow central region will be filled by the downstream end of the cylindrical member 30 and by the pilot fuel passing through the pilot jet orifice 31.

The parts of the burner described above are mounted within a housing member 51. The latter is itself mounted within a casing member 52 so as to form an annular duct 53 therewith. The duct 53 is open at its upstream end to a supply of ambient air which thus passes through the duct 53 and is directed by fr-usto- conical surfaces 54, 55 on the housing member 51 and on a cylindrical member 56 so as to direct the air towards the main jet orifice 40 and the pilot jet orifice 31.

The cylindrical member 56, which is disposed concentrically of the cylindrical member 30 and is spaced from the latter to provide the duct 50, has an outer surface 60 which is disposed adjacent to, but very slightly spaced from, a surface '61 on the housing member 51. The gap between the surfaces 60, 61 extends between fuel reser voirs 62, 63 which are formed in the cylindrical member 56, the reservoir 62 being supplied with fuel by way of drillings 64 which communicate with the tangential slots 47. There will thus be a thin film of fuel which will at all times, in the operation of the burner, pass from the reservoir 63 and flow downwardly over the surface 55 so as to assist in preventing the formation of carbon deposits on the latter. The passage of air over the surface 55 will assist the entrainment of this flow of fuel thereover.

In FIGURE 3 there is shown a modified burner, many of whose parts are the same as the corresponding parts of FIGURE 2, and which have therefore been given the same reference numerals. For this reason, moreover, a detailed description of FIGURE 3 will not be provided.

In the FIGURE 3 embodiment, however, the interior of the cylindrical member 30 is provided with an axially extending duct 65 which, unlike the duct 27, is not an annular duct since no sleeve member 32 is provided in the FIGURE 3 embodiment. Moreover, the distance piece 23 is provided with a central portion 66 which, unlike the central portion 33 of the FIGURE 2 embodiment, does not have a bore extending therethrough which communicates with the fuel chamber 22,

In the FIGURE 3 embodiment, on the contrary, the central portion 66 is formed with a conduit 67 whose downstream end communicates with the duct 65 and whose upstream end communicates with a drilling 68. The drilling '68 extends through the distance piece 23 and through the housing member 51 so as to be open to the flow of ambient air. Accordingly, ambient air at a relatively high pressure will enter the central region of the duct 65 and will thus prevent or impede the passage of combustion gases upstream through the pilot jet orifice 31. Thus the hollow central region of the annular vortex flow of pilot fuel is substantially filled with air at higher pressure than the combustion gases immediately outside the burner.

The drilling 68 is desirably arranged to pick up as great a dynamic head as possible. To this end, the drilling 68 may, if desired, be arranged to extend through the block 21 instead of through the housing member 51.

We claim:

1. A burner having an unobstructed jet orifice, a fuel chamber in said burner adapted to be supplied with fuel, a fuel feed annulus, at least one passage which leads from the fuel chamber to the fuel feed annulus, an axially extending duct leading to the jet orifice, tangential swirl slots leading tangentiallyfrom the fuel feed annulus to the axially extending duct whereby an annular vortex flow having a hollow central region is, in operation, pro duced in the axially extending duct, and a conduit extend ing from said fuel chamber to said axially extending duct to supply unatomized liquid fuel to said hollow central region of the annular vortex flow.

2. A burner as claimed in claim 1 in which the conduit communicates, at a point upstream of the jet orifice, with the axially extending duct.

3. A burner as claimed in claim 1 in which the said axially extending duct is annular, and wherein the conduit communicates with the said fuel chamber.

4. A burner as claimed in claim 1 in which the said axially extending duct is annular, and the conduit communicates with the said annular axially extending duct.

5. A burner as claimed in claim 3 in which the axially extending duct has an unobstructed frusto-conical portion at its downstream end, with the said conduit means supplying fuel to the center of the said frusto-conical portion.

6. A burner as claimed in claim 1 in which the said jet orifice is a pilot jet orifice which is disposed centrally of an annular main jet orifice, and second conduit means being provided for supplying the main jet orifice with an annular vortex flow of fuel.

7. A gas turbine engine combustion chamber provided with at least one burner as claimed in claim 1.

References Cited UNITED STATES PATENTS 1,381,095 6/1921 Starr 239-400 2,561,939 7/1951 Meshino 60-39.74 2,595,759 5/1952 Buckland 6039.74 2,771,744 11/1956 Johnson 6039.74 2,907,527 10/1959 Cummings 60-39.74 3,078,046 2/1963 'Iyler 239126 3,091,926 6/1963 Watkins 60-3928 D. HART, Assistant Examiner MARK M. NEWMAN, Primary Examiner US. Cl. X.R.

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