US3535875A - Annular fuel vaporizer type combustor - Google Patents

Description

Oct. 27, 1970 R. J. SNEEDEN ETA!- ANNULAR FUEL VAPORIZER TYPE COMBUSTOR .4 Sheets-Sheet 1 Filed Nov. 27, 1968 NEIL R. BROOKES WILLIAM l. ITKE BY RALPH J. SNEEDEN WA DZW ATTORNEY Oct. 27, 1970 J SNEEDEN ETAL 3,535,875

ANNULAR FUEL VAPORIZER TYPE COMBUSTOR Filed NOV. 27, 1968 .4 Sheets-Sheet 2 F 3 IINVENTORS L R. BROOKES LIAM L/TKE BY RALPH J. SNEEDEN ATTORNEY Oct. 27, 1970 SNEEDEN ETAL 3,535,875

ANNULAR FUEL VAPORIZER TYPE COMBUSTOR Filed Nov. 27, 1968 4 Sheets-Sheet 3 ATTORNEY Oct. 27, 1970 J,-SNEEDEN ETAL I 3,535,875

" ANNULAR FUEL VAPORIZER TYPE COMBUSTOR Filed Nov. 27', 1968 4 Sheets-Sheet 4 INVENTORS NEIL R. BROOKES WILLIAM LITKE BY RALPH J. SNEEDEN ATTORNEY United States Patent ANNULAR FUEL VAPORIZER TYPE COMBUSTOR Ralph J. Sneeden, Boxford, and Neil R. Brookes, Topsfield, Mass., and William Litke, Franklin Lakes, N.J.,

assignors to Curtiss-Wright Corporation, a corporation of Delaware Filed Nov. 27, 1968, Ser. No. 779,352 Int. Cl. F02c 3/22 US. Cl. 6039.71 3 Claims ABSTRACT OF THE DISCLOSURE Combustion apparatus of the fuel vaporizer type having a single fuel vaporizing unit coaxial with the combustion chamber, said unit providing an annular air-fuel passage which extends downstream into the combustion chamber and then turns radially outwardly and finally back on itself so that its annular discharge end faces to- Ward the upstream end of the combustion chamber.

BACKGROUND OF THE INVENTION The invention relates to combustion apparatus and is particularly directed to improved combustion apparatus for gas turbine engines.

The invention concerns combustion apparatus of the fuel vaporizer type, such as disclosed in US. Pat. No. 3,276,676. This prior art patent discloses a plurality of fuel vaporizer units spaced circumferentially about the axis of a combustion chamber, as well as being spaced radially across said chamber. This prior patent utilizes such a plurality of fuel vaporizer units in order to achieve substantially uniform combustion gas temperatures across the combustion chamber. In accordance with the present invention, these results are achieved with a novel and simple combustion apparatus having but a single fuel vaporizing unit disposed on the axis of the combustion chamber with this single vaporizing unit having an annular fuel-air path compared to the tubular fuel-air path of the vaporizing units of said prior patent.

SUMMARY An object of this invention comprises the provision of a novel and simple combustion apparatus of the fuel vaporizer type. More particularly, it is an object of this invention to provide novel and simple combustion apparatus having only a single fuel vaporizer unit on the axis of the combustion chamber with said unit having an annular fuel-air path.

In accordance with the invention, the fuel vaporizer unit is coaxially supported adjacent to the upstream wall of a combustion chamber. This fuel vaporizer unit has radially-spaced inner and outer annular walls extending through said upstream wall into the combustion chamber and forming an annular air-fuel passage between said walls. The inner annular wall of said passage extends axially downstream beyond the annular outer wall of said passage and turns radially outwardly beyond said outer wall and then reverses and turns in an upstream direction radially outwardly of said outer wall to overlap said outer wall so that the annular passage first extends downstream and then turns radially outwardly and finally turns back on itself such that its annular discharge opening faces in an upstream direction toward the upstream wall of said chamber.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic view in axial section of a gas turbine engine having a combustion unit embodying the invention;

FIG. 2 is a view taken along line 22 of FIG. 1;

FIG. 2A is a perspective view of a portion of FIG. 2;

FIG. 3 is a partial view similar to FIG. 1 but illustrating combustion apparatus having an annular combustion chamber instead of the cannular chamber of FIG. 1;

FIG. 4 is a diagrammatic view similar to FIG. 3 but illustrating a gas turbine engine in which the combustion chamber is annular and surrounds the turbine shaft;

FIG. 5 is a developed sectional view taken on line 55 of FIG. 4; and

FIG. 6 is a view similar to FIG. 5 but in which fuel is discharged into the annular passage of the fuel vaporizer unit by means of a rotating slinger arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 1 and 2 of the drawing, a gas turbine engine, schematically indicated by reference numeral 10, comprises a combustor unit 12, a turbine unit 14 and a compressor unit 1 6. The turbine unit 14 consists of a turbine rotor 18 having a plurality of circum ferentially-spaced blades 20 extending radially therefrom. The turbine rotor is driveably connected to the rotor 22 of the compressor unit 16' by a shaft 24,-as well as to the other apparatus (not shown) to be driven by the turbine engine. The compressor rotor 22 has a plurality of circumferentially-spaced blades 26 which, upon being driven by the turbine rotor 18, draw air into the compressor from the compressor intake 28 and discharge compressed air into its output passage, schematically indicated at 30. The compressor output passage 30 supplies compressed air to the upstream end of the combustor unit 12.

The combustor unit 12 consists of an outer annular housing 32 and the arrows 34 represent compressed air being supplied to the upstream end of this housing for combustion therein with fuel so as to supply the combustion gases for reaction with the turbine blades 20 so as to drive the turbine rotor. The structure of the drawing so far described is conventional and forms no part of the present invention.

The combustor housing 32 is coaxial with the turbine rotor 18 and has a coaxial annular liner 36 and a domelike liner or cap 38 over the upstream end of the turbine rotor 18. A Wall 40 is disposed across the upstream end of the annular liner 36 so that the liner 36, cap 38 and wall 40 form a combustion chamber 42 therebetween. The downstream end of the chamber 42 has a coaxial annular discharge passage 44 having circumferentiallyspaced guide or nozzle vanes 46 extending radially thereacross for directing the combustion gases toward the turbine blades 20 for driving the turbine. The combustion gases exhaust from the turbine through a duct 48 and thence in the case of a turbojet engine through a nozzle for providing the engine with forward thrust.

A fuel vaporizer unit 50 is coaxially supported at the upstream end of the combustion chamber 42 by its upstream wall or head plate 40. As illustrated, the fuel vaporizer unit 50 has a multi-part construction comprising first and second hollow cylindrical members 52 and 54 coaxially secured together by a bolt 56 and an inner core and spacer element 58. As shown, the first cylindrical member 52 is formed integral with the upstream wall 40 of the combustion chamber 42, whereby the entire fuel vaporizer unit 50 is supported by this wall. The core 58 also serve to position the hollow cylindrical members 52 and 54 in axial and radial spaced relation relative to each other.

The first and second hollow cylindrical members 52 and 54 have axially extending coaxial annular walls 60 and 62, respectively, said annular walls extending downstream from the combustion chamber upstream wall or head plate 40 in a downstream direction into the combustion chamber 42. As illustrated, the annular wall 60 is radially spaced outwardly of the wall 62. The inner annular wall 62 extends downstream beyond the outer annular wall 60 and at its downstream end has a portion 64 which turns radially outwardly beyond the wall 62 and then has an annular portion 66 which turns back on itself and overlaps the annular wall 60. With this construction, the hollow cylindrical members 52 and 54 with their axially extending radially-spaced walls 60 and 62 form an annular passage 68 therebetween which extends through and downstream beyond the combustion chamber wall 40 and then at its downstream end turns radially outwardly and finally turns in an axial upstream direction so that its annular discharge end 70 faces toward the upstream wall 40 of the combustion chamber 42.

The upstream wall of the hollow member 52 has a plurality of circumferentially-spaced openings 72 for admitting compressed air into the annular passage 68. That is, a portion of the compressed air supplied to the combustion unit, as diagrammatically indicated by the arrows 34, flows through the openings 72 into the annular passage 68 of the fuel vaporizer unit 50.

A ring 74 is mounted about the annular wall 60. Fuel for combustion in the combustion chamber 42 is supplied to the ring 74 by a fuel supply line schematically indicated at 76. The fuel supply line terminates in an annular channel 78 on the inner surface of the ring 74. The wall 60 has a plurality of circumferentially-spaced passages 80 therethrough communicating with the annular channel 78, whereby fuel is discharged into the annular passage 68 from the passages 80.

The upstream wall 40 of the combustion chamber 42 also has a plurality of circumferentially-spaced air passages 82 therethrough lying on a circle which is coaxial with and is disposed about the fuel vaporizer unit 50. Each of the air passages 82 consists of a cup-shaped member 84, the open end of which faces in an upstream direction through the wall 40, each said cup-shaped member being supported by said wall. The circle on which the circumferentially-spaced, cup-shaped members lie is sufficiently greater in diameter than the outer diameter of the annular discharge opening 70 of the passage 68 so that each cup-shaped member 84 is entirely disposed radially outwardly of said outer diameter of the annular discharge opening 70.

As best seen in FIG. 2A, each cup-shaped member 84 has a slot 86 across the bottom end of said member through which slot air discharges into the combustion chamber 42. Each slot 86 preferably is disposed radial relative to the combustion chamber axis, as illustrated in FIG. 2, and extends through the bottom wall of its cupshaped member 84 and also through diametrically opposed portions of the side wall of said cup-shaped member, thereby providing said member with air flow openings in both its bottom and side walls. Each cup-shaped member 84 may also have a plurality of circumferentially-spaced openings 88 in its side wall for additional lateral air flow therethrough.

The air supplied through the annular passage 68 and that supplied through the passages 82 provided by the cup-shaped member 84 is the primary air for combustion of the fuel in the combustion chamber 42. The combustion chamber head plate or upstream wall 40 in elfect provides a baffie which prevents compressed air from discharging directly into the combustion chamber other than through the annular passage 68 of the fuel vaporizer unit 50 and through the air passages 82.

The fuel supplied to the annular passage 68 is carried along said passage by the air flow therethrough. The resulting air-fuel mixture in the passage 68 is fuel rich and discharges from the discharge end 70 of said passage toward the upstream wall 40 of the combustion chamber. The wall 40 turns this fuel-air mixture radially outwardly for mixture with the remaining primary air supplied through the passages 82 provided by the cup-shaped members 84. This fuel-air mixture is ignited by a suitable igniter, schematically indicated at 90, for combustion within the combustion chamber 42. The heat of combustion in the chamber 42 serves to pre-heat and vaporize the fuel in the annular passage 68 as it is carried along this passage by the air flow therethrough, whereby the fuel is pre-heated, vaporized and thoroughly mixed with the air in this passage before it is discharged from the passage end 70 into the combustion chamber 42.

In order to ensure good mixture of the fuel-air mixture discharging from the annular passage 68 with the remaining primary air discharging from the cup-shaped members 84, the downstream end of each cup-shaped member 84 preferably, as illustrated, is disposed upstream of the discharge end 70 of the annular passage 68. Since the discharge slots 86 across the bottom ends of the cup-shaped members 84 are radially disposed relative to the axis of the vaporizer unit 50, the air discharging from these slots comprises radially-oriented, fan-shaped streams of air discharging from the cup-shaped members 84. As a result, there is a circumferentially-spaced plurality of fan-shaped jets of air surrounding the vaporizer unit 50. These fan-shaped jets entrain the fuel rich mixture discharging from the end 70 of the vaporizer unit passage 68 with the result that combustion occurs along the edges of said fan-shaped jets. Since the fuel mixture flowing through the vaporizer unit passage 68 is pre-heated, vaporized and thoroughly mixed with the air flowing through this passage before it discharges from the end 70 of this passage, ignition delay time in the combustion chamber 42 is substantially reduced. This reduction in ignition delay time minimizes the length of time the fuel-air mixture must remain in the combustion chamber 42 for combustion to be complete. Hence, the present invention also minimizes the required length of the combustion chamber for complete combustion.

In order to cool the combustion chamber annular liner 36 and cap liner 38 and to cool the combustion gases themselves, secondary air is introduced into the combustion chamber 42 through said liners, as indicated by the arrows 92, 94 and 96. For this purpose, said liners may be made of porous or perforated material to permit such air flow therethrough. In addition, the turbine nozzle vanes 46 are made hollow to provide air flow therethrough into the space between the cap liner 38 and the turbine rotor 18. In this way, the combustion chamber 42 is provided with secondary air for cooling the combustion gases and for cooling the annular liner 36 and cap liner 38. The detailed constructions of the liners 36 and 38 form no part of the present invention. These liners may have a multi-part, perforated construction similar to the construction of the combustion chamber liners in aforementioned U.S. Pat. No. 3,376,676.

The embodiment of FIGS. 1 and 2 provides a combustion chamber 42 of a cannular configuration. FIG. 3 is a partial view similar to FIG. 1 but showing a modification in which the combustion chamber has an annular configuration. The embodiment of FIG. 3 is otherwise like that of FIGS. 1 and 2 and, for ease of understanding, those parts of FIG. 3 corresponding to parts of FIGS. 1 and 2 have been indicated by like reference numerals but with a subscript a added.

In FIG. 3 the cap liner 38 of FIG. 1 has been replaced by an inner annular liner 98, the upstream end of which is connected to the outer downstream edge of the fuel vaporizer unit 50a. This gives the combustion chamber 42a an annular configuration instead of the cannular configuration of FIG. 1. The remaining structure of FIG. 3 is like that of FIG. 1 and therefore no further description of FIG. 3 appears necessary, its operation being essentially the same as FIG. 1.

FIGS. 4 and 5 illustrate a further embodiment in which the combustor unit surrounds the turbine shaft. The embodiment of FIGS. 4 and 5 is otherwise generally similar to FIG. 3 and, for ease of understanding, those parts of FIGS. 4 and 5 corresponding to parts of FIG. 3 have been indicated by like reference numerals but with a subscript b added.

In FIG. 4 the combustion chamber 42b is annular as in FIG. 3 but in FIG. 4 this chamber surrounds the tur- Ibine shaft 24b. In addition, the shaft 24b is connected to the rotor 22b of an axial flow-type compressor instead of the centrifugal-type compressor of FIGS. 1 and 3.

The fuel vaporizer unit 50b in FIG. 4 differs from that of FIGS. 1 and 3 in that the turbine shaft 24b passes through the unit 50 1:. The inner annular wall 62b of the annular fuel-air passage 68b surrounds the shaft 24b in radially-spaced relation so as to provide an annular passage 100 therebetween. With this arrangement, secondary air is supplied inwardly of the combustion chamber liner 98b through said annular passage 100. Accordingly, with the arrangement of FIG. 4, the turbine nozzle vanes 4617 need not be hollow to provide secondary air to the inner side of the liner 98b, as is necessary in FIGS. 1 and 3.

In FIG. 4 circumferentially-spaced vanes -2 are provided across the upstream end of the annular fuel-air passage 68b.'These vanes preferably have a helical orientation about the axis of the passage 68b, as best indicated in FIG. 5, so as to impart a swirl component to the air entering the passage 686 about the axis of said passage. In addition, the fuel passages 80b preferably are also inclined relative to the axis of the passage 68b so as to impart a swirl component to the fuel about the axis of said passage in the same direction as the air swirl component. This inclination of the fuel passages 80b is also best seen in FIG. 5. The swirling motion of the fuel and air as it flows through the passage 68b promotes more thorough mixing of the fuel and air flowing therethrough. Obviously, similar means may be provided in FIG. 1 to provide for a swirling flow component for the fuel and air in the passage 68 about the axis of said passage and such means may also be included in FIG. 3.

Except for the swirling flow motion of the fuel and air in the passage 68b about the axis of said passage, the operation of FIGS. 4 and 5 is essentially that of FIGS. 1 and 3 and therefore no further description of FIGS. 4 and 5 is necessary.

Reference is now made to FIG. 6. This embodiment is like that of FIG. 4 in that the combustion chamber surrounds the turbine shaft and the turbine shaft extends coaxially through the fuel vaporizer unit. For ease of understanding, the parts of FIG. 6 corresponding to parts of FIG. 4 have been indicated by the same reference numerals but with a subscript 0 added.

FIG. 6 dilfers primarily from FIG. 4 in that the downstream end of the inner annular wall 620 of the annular passage 68c of the vaporizer unit 50c is formed by a rotating annular wall portion or slinger 110. The slinger 110 has a hub portion secured to the turbine shaft 240 as by a nut 114. Also, for structural reasons, the wall portions 60c, 62c and 660 are interconnected by a plurality of circumferentially-speced ribs 116 and 118. These ribs may have a helical orientation like the vanes 102 of FIG. 4 for imparting a swirl component to the air-fuel mixture flowing through the passage 680. Also, for fabrication reasons, the wall portion 600 has a multi-part construction, as illustrated.

The annular slinger has a concave profile on its inner side facing the shaft 24b. The fuel passage or passages 800 are disposed to discharge fuel into the space between this concave side of the slinger 110 into shaft 24b. As a result of rotation of the slinger and the resulting centrifugal forces, the fuel collects in an annulus on the inner concave side of the slinger. A plurality of circumferentially-spaced holes are provided radially through the slinger 110 so that this fuel discharges radially outwardly therethrough into the passage 68c, said fuel discharging through said holes under the action of the centrifugal forces acting thereon. In this way the fuel is discharged in a plurality of fine spray jets into the passage 68c where it is promptly vaporized by heat from combustion in the combustion chamber 420.

It should be noted that the portion of the slinger 110 having the holes 120 in effect forms a downstream portion of theinner wall 620 of the annular passage 68c. Also, in FIG. 6, the vanes 460 are made hollow, as in FIGS. 1 and 3, in order that secondary air be supplied therethrough to the inner side of the inner annular combustion chamber liner 98c.

Except for the manner in which fuel is discharged into the annular passage 680, the operation of the combustion structure of FIG. 6 is essentially like that of FIG. 4. Hence, no further description of FIG. 6 is necessary.

While we have described our invention in detail in its present preferred embodiments, it will be obvious to those skilled in the art, after understanding our invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. We aim, in the appended claims, to cover all such modifications.

What is claimed is:

1. Combustion structure comprising:

(a) a casing forming a combustion chamber having an annular discharge opening at its downstream end and having a wall coaxial with said opening disposed across the upstream end of said chamber;

(b) means providing an annular air passage extending through said wall for supplying air therethrough, said annular air passage being coaxially disposed relative to said chamber discharge opening with the inner wall of said passage extending axially in a downstream direction beyond its outer wall and tuming radially outwardly and then reversing in an upstream direction radially outwardly of said outer wall to overlap at least a portion of said outer wall so that said annular passage first extends downstream and then turns radially outwardly and back on itself, whereby its annular discharge opening faces in an upstream direction toward said upstream chamber wall;

(c) means for introducing fuel into the downstream extending portion of said annular air passage so that fuel discharges from said annular passage in an upstream direction toward said wall for combustion in said chamber with air also discharging from said passage;

(d) said wall having a plurality of air opening means for providing additional air for combustion with said fuel, said air opening means being circumferentially spaced about said annular passage on a circle which is coaxial with said passage and which has a diameter greater than the outer diameter of the annular discharge opening of said passage;

(e) each of said air opening means comprising a cup shaped member having its mouth end opening through said wall and in Which the sides and bottom of each cup-shaped member have openings for air 8 to discharge therethrough, the bottom of each cup- '3. Combustion structure as recited in claim 1 and in shaped member being disposed closer to said wall which each cup-shaped member has a slot-like opening than the discharge end of Said annular P across its bottom and is disposed generally radial to the the circle on which the centers of the P* P Circle on which the cup-shaped members are disposed.

members lie being sufiiciently greater in diameter 5 than the outer diameter of the discharge opening of References Cited the annular passage so that each cup-shaped member is entirely disposed radially outwardly of said UNITED STATES PATENTS outer diameter of said annular discharge opening. 2,646,664 7 /1953 Meschino 2. C0mbust1on structure as defined in claim 1 for a 10 2,727,358 12/1955 Howes turbine engine having a shaft coaxial with said annulacrl' 2 994192 8/1961 Eisele 71 air passage, at least a portion of t e inner wall of sai annular air passage being rotatably connected to said 222 shaft, said portion being concave on its inner surface and having a plurality of radial holes therethrough, said concave portion having a lip at its upstream end extending 15 DOUGLAS HART 'Pnmary Examiner radially inward, the fuel supplied to said annular passage being supplied to the inner side of said concave wall portion for discharge through said holes into said passage by 39-74 centrifugal action. 20

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