Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3899884 A
Publication typeGrant
Publication dateAug 19, 1975
Filing dateDec 2, 1970
Priority dateDec 2, 1970
Also published asCA943352A1, DE2143012A1, DE2143012B2, DE2143012C3
Publication numberUS 3899884 A, US 3899884A, US-A-3899884, US3899884 A, US3899884A
InventorsEdward E Ekstedt
Original AssigneeGen Electric
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Combustor systems
US 3899884 A
Abstract
The disclosure shows two versions of providing a venturi around a fuel spray cone in a mixing chamber having an axial, vortical flow of pressurized air therethrough. This mixture is discharged into a combustion chamber. The venturi maintains desirable low smoke formation while spacing the flame front of the ignited mixture from the spray nozzle to reduce its temperature and thus prevent undesired carbon formation thereon.
Images(2)
Previous page
Next page
Description  (OCR text may contain errors)

United States Patent Ekstedt Aug. 19, 1975 1 COMBUSTOR SYSTEMS 3,430,443 3/1969 Richardson 60/39.65 3,570,242 3/1971 Leonardi 431/183 [75] hvemo 3 3 Eksted" Cmcmnau, 3,589.127 6/1971 Kenworthy 60/39.65

[73] Assignee: General Electric Company, Primary ExaminerDoug1as Hart Cincinnati, Ohio Attorney, Agent, or Firm-Lee H. Sachs; Derek P. 22 Filed: Dec. 2, 1970 Lawrence The disclosure shows two versions of providing a ven- [52] U.S. Cl. 60/39.74 R; 431/183 i around a f l Spray Cone in a mixing Chamber [5 Clhaving an axial vortical flow of pressurized air there- Field of Search 60/3965 39-74; 431/183 through. This mixture is discharged into a combustion chamber. The venturi maintains desirable low smoke [56] References Clted formation while spacing the flame front of the ignited UNITED STATES PATENTS mixture from the spray nozzle to reduce its tempera- 1,290,607 1/1919 Lovekin 431/183 ture and thus Prevent undesired carbon formation 1,322,999 11/1919 Bester 60/39.65 thereon- 2,398,654 4/1946 Lubbock... 60/39.65 3 Cl 4 D 3,285,007 11/1966 Carlisle 60/39.74 R raw'ng gums III! III/III/lfl PATENTEUAUG-I ems 3, 899 884 SWEET 1 [1F 2 INVENTOR. EDWARD E. EKSTEDT nrromiEY- PATENTEU W75 3, 899 884 SZIET 2 UF 2 INVENTOR. EDWARD E. EKSTEDT ATTORNEY- COMBUSTOR SYSTEMS The invention herein described was made in the course of or under a contract, or a subcontract thereunder, with the U.S. Department of the Air Force.

The present invention relates to improvements in combustor systems, particularly in the generation of a hot gas stream as in gas turbine engines.

Combustor systems, as employed in gas turbine engines, comprise a spray nozzle which injects fuel into a combustion zone. Once ignited, a continuous flame front is maintained in the combustion chamber as fuel and pressurized air flow therein and a high energy, hot gas stream is discharged therefrom.

Recent emphasis had been placed on the problem of minimizing smoke generated in the combustion process and discharged to the atmosphere from gas turbine engines. One highly successful approach to this problem has been to discharge the fuel into a conduit or mixing chamber which opens into the combustion chamber. Pressurized air is introduced axially and swirled vorti cally about the discharge axis of the spray nozzle. In so doing, the turbulent flow field created produces a highly dispersed, over-stoichiometric mixture of fuel and air in the conduit. This mixture is discharged in a generally conical fashion into the combustion chamber where it is further dispersed by additional air entering other openings in the combustion chamber. This addi tional air is sufficient to sustain combustion and a flame front is produced in this mixing zone at the mixing chamber discharge. Because of the high degree of dispersion obtained, over-rich fuel zones are essentially eliminated and smoke is minimized to the point of being virtually undetectable.

While smoke is thus effectively reduced, the frequency of maintenance of the fuel nozzles has increased. This is due to the coking of fuel on the nozzles which adversley affects the pattern of the fuel spray cone discharged therefrom. Various forms of spray nozzles and air shrouds therefor have had limited degrees of success in overcoming this problem and still maintaining minimized smoke levels. This lack of success is attributed to the fine dispersion of fuel which recirculates, in localized regions, and contacts the discharge end of the nozzle. The fuel then cokes or carbonizes when it contacts the nozzle due to the high temperature thereof.

Accordingly, the object of the invention is to reduce the temperature levels of fuel nozzles and, in so doing, minimize the buildup of carbon thereon and further, to maintain minimal smoke generation in the combustion process.

These ends are broadly attained by providing a venturi means into which the fuel spray is discharged. The acceleration provided by the initial portion of the venturi tube accelerates mixing air introduced around the nozzle to an extent sufficient to prevent combustion for a predetermined distance from the nozzle. By thus displacing the flame front from the nozzle, its temperature may be reduced sufficiently to prevent undesirable carbon buildup thereon. The divergent portion of the venturi tube re-expands the mixing air to discharge it into the combustion chamber at a relatively wide angle consistent with the smoke minimizing dispersion process referenced above.

Other features are found in the relationship of the venturi tube to the means for introducing mixing air as well as in the amount of mixing air introduced.

The above and other related objects and features of the invention will be apparent from a reading of the following description of the disclosure found in the accompanying drawings and the novelty thereof pointed out in the appended claims.

In the drawings:

FIG. 1 is a schematic representation of a gas turbine engine employing a combustor of the type herein referenced;

FIG. 2 is an enlarged longitudinal section illustrating the details of the combustor referenced in FIG. 1 as they embody the present invention;

FIG. 3 is a section taken on line IIl-IlI in FIG. 2; and

FIG. 4 is a longitudinal section, similar to FIG. 2, illustrating another embodiment of the invention.

Referencing FIG. 1, the illustrated engine comprises an axial flow compressor 10 which pressurizes air. This pressurized air flows through an annular passageway 12 to an annular combustor 14 where fuel is introduced. The pressurized air supports combustion of fuel within the combustor to generate a high energy level, hot gas stream. This hot gas stream drives a turbine 16 which in turn powers the rotor of the compressor 10. The hot gas stream is then converted to a useful output as by being discharged from a nozzle 17 to provide propulsive. thrust for an aircraft.

The combustor 14, as illustrated in FIG. 2, comprises outer and inner liners 18 and 20 which define an annular combustion chamber 21. These liners are joined by compositely formed dome portion 22 at their upstream ends. Cylindrical conduits or mixing chambers 24 which open into the dome portion 22 and the combustion chamber 21. Transition segments 26 blend the conduit openings into the dome portion. An axial flow swirler 28 is mounted at the upstream end of each conduit 24.

The swirler has a central opening which receives the discharge end 29 of a fuel spray nozzle 30. The nozzle 30 may take many forms but is preferably characterized by at least one orifice outlet which produces a conical spray discharge having a relatively large included angle relative to an axis a which extends lengthwise of the mixing chamber. The swirler 28 includes a row of passageways 32 annularly surrounding the axis of the nozzle discharge end 29. The passageways 32 are angled relative to the nozzle axis to produce a vortical flow field.

The swirler 28 may be mounted on the upstream end of the conduit 24 in the manner taught in copending US. application Ser. No. 796,391, filed Feb. 4, 1969 and of common assignment. The referenced application also describes in further detail, the relationship of the swirler passageways 32 in obtaining a high degree of fuel dispersion for low smoke combustion.

Introduction of pressurized air from the annular compressor discharge passageway 12 into the combustion chamber 21 will now be described. The passageway 12 is defined by outer and inner, generally cylindrical casings 34 and 36 which extend along the lengths of the liners 18 and 20 are respectively spaced therefrom to define annular passageways 38 and 40. An annular snout assembly 42 is secured to and projects upstream from the liners l8 and 20. The snout assembly has a central passageway 43 having an entrance facing the discharge passageway 12 and discharging into an annular chamber 44 surrounding the entrances to the mixing chambers, i.e., swirler passageways 32. The pressurized discharge from the compressor then is split into three annular flow-paths along passageways 38, 40 and 43.

Air from the passageways 38 and 40 may enter the combustion chamber 21 to serve three functions. First, it may pass through relatively small holes 46 which are oriented to cool the liners 18 and 20. Second, it may enter relatively large holes 48 to penetrate the combustion chamber and supply requisite, primary air for the combustion process. Third, it may enter holes (not shown) further downstream as dilution air to reduce the temperature of the hot gas stream to a temperature compatible with the capabilities of the materials forming the turbine. The air entering holes 48 may also serve a dilution function.

Air entering the snout passageway 43 and chamber 44 is then metered by and injected into the mixing chamber as discrete jets by the swirler passageways 32. The vortical flow of mixing air is highly effective in dispersing or mixing the fuel from the spray cone into fine droplets which support a combustion process at a flame front generally identified by the broken line in FIG. 2.

The flame front is primarily controlled by two factors, once ignition is had. These are the presence and degree of a combustible mixture and the velocity of that mixture. In accordance with the present invention, these factors are taken into account in maintaining a desired distance between the flame front and the discharge end 29 of the fuel nozzle to minimize the temperature of the latter.

To this end, a venturi tube 50 is disposed concentrically of the nozzle axis a in a surrounding relationship with the spray cone discharged by the nozzle. The inlet diameter of the venturi tube approximates the mean diameter of the annular row of swirler passageways 32. Thus approximately one-third of the swirler mixing air is captured by and axially accelerated through the convergent portion of the venturi tube 50. This creates a condition of where the mixture, at the throat of the venturi, is sufficiently over-stoichiometric as not to support combustion and the mixture velocity is increased to further deter combustion. The divergent portion of the venturi tube then re-expands the mixture to approximately the original cone shape of the nozzle discharge. In this connection, it will be noted that the divergent portion of the venturi terminates at a generally tangent relationship with the spray cone.

While maintaining the desired low smoke characteristics, the venturi tube 50 is highly effective in maintaining the flame front at a desired downstream distance. This distance can be controlled as desired by the length of venturi tube and its contraction ratio as well as the amount of mixing air flow therethrough, all of these factors being balanced so that the spray cone angle is relatively divergent as it discharges from the venturi tube into the combustion chamber.

The effect of the venturi tube may be expressed in another fashion in that it increases the total pressure in the core of the vortical flow field created by the axial flow swirler. Without the venturi, the low pressure of the vortical core would enable recirculating primary air to flow forwardly, as indicated by the broken arrows, and create a combustible mixture and flame front closely adjacent the nozzle discharge. With the venturi such recirculation occurs, as indicated by the solid arrows, but is more limited in the magnitude of its upstream movement.

It will be noted that the venturi tube is welded or otherwise bonded to the swirler 28 intermediate the lengths of the passageways 32. In so doing, added strength and rigidity is obtained for the swirler.

FIG. 4 illustrates an embodiment of the invention wherein all of the mixing air flows through a venturi tube 52 which also serves as a mixing chamber for introducing the dispersed fuel mixture into the combustion zone. The action of this venturi in obtaining a desired downstream displacement of the flame front and a consequent reduction in nozzle temperature is essentially the same as previously described except that the velocity factor of the venturi is more predominant in displacing the flame front since a greater amount of air enters the venturi. In fact, the benefits of the broader aspects of the present invention can be attained where the amount of mixing air flow is sufficient to produce a combustible mixture in the mixing chamber.

It has been demonstrated that the described use of a venturi is highly efiective in preventing carbon buildup on fuel nozzles and, thus, assuring long maintenancefree operation. At the same time, low smoke levels continue to be maintained. 7

While the invention has been described with reference to an annular combustion system, it is equally applicable to a cannular system. Further, in the broader aspects of the invention, the mixing air could flow through the mixing chamber with little or no vortical component. These and other variations in the described embodiments will occur to those skilled in the art within the spirit and scope of the present inventive concepts which are to be derived solely from the appended claims.

Having thus described the invention, what is claimed as novel and desired to be secured by Letters Patent of the United States is:

1. A combustor system comprising:

a combustion chamber,

a mixing chamber opening into the upstream end of the combustion chamber,

a spray nozzle for discharging fuel as an atomized cone into said mixing chamber, the axis of said spray cone extending lengthwise of said mixing chamber toward said combustion chamber,

means for introducing pressurized air into the upstream end of said mixing chamber and producing an axial flow field for dispersing the fuel in fine droplets,

venturi means surrounding said spray cone and through which at least a portion of the axially flowing air passes, and wherein the air introducing means additionally provide a vortical component to the air flow field,

the venturi means comprise a venturi tube mounted within said mixing chamber,

a cylindrical conduit and an axial swirler at the upstream end of the conduit define said mixing chamber,

said air introducing means includes an annular row of generally radially on'ented passageways angled through said swirler,

said axial swirler has a central opening through which the discharge end of the spray nozzle projects, and

the inlet end of the venturi tube has a diameter intermediate the minimum and maximum diameters of the annular row of swirler passageways and is bonded to said swirler.

6 2. A combustion chamber as in claim I wherein the chamber at a rate insufficient to produce a comdivergent discharge end of the venturi tube terminates bustibie mixture with the f l introduced by said generally as a tangent to the spray cone discharge from Spray noflle and the nozzle.

3. A combustor as in claim 2 wherein: a pressurized plenum is provided, in combination with the upstream face of said axial swirler, and Produce a Combustible mixture thereinthe swirler passageways meter air into the mixing means are provided for introducing further pressurized air into said combustion chamber sufficient to

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1290607 *May 10, 1917Jan 7, 1919Schutte & Koerting CompanyAir-register for oil-burners.
US1322999 *Nov 4, 1918Nov 25, 1919 Hybrqgarbgn-burher
US2398654 *Jun 30, 1941Apr 16, 1946Anglo Saxon Petroleum CompanyCombustion burner
US3285007 *Oct 26, 1964Nov 15, 1966Rolls RoyceFuel injector for a gas turbine engine
US3430443 *Feb 17, 1967Mar 4, 1969Bristol Siddeley Engines LtdLiquid fuel combusion apparatus for gas turbine engines
US3570242 *Apr 20, 1970Mar 16, 1971United Aircraft CorpFuel premixing for smokeless jet engine main burner
US3589127 *Feb 4, 1969Jun 29, 1971Gen ElectricCombustion apparatus
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4215535 *Jan 19, 1978Aug 5, 1980United Technologies CorporationMethod and apparatus for reducing nitrous oxide emissions from combustors
US4445338 *Oct 23, 1981May 1, 1984The United States Of America As Represented By The Secretary Of The NavySwirler assembly for a vorbix augmentor
US4458479 *Oct 13, 1981Jul 10, 1984General Motors CorporationDiffuser for gas turbine engine
US4584834 *Jul 6, 1982Apr 29, 1986General Electric CompanyGas turbine engine carburetor
US4693074 *May 16, 1986Sep 15, 1987Rolls-Royce PlcCombustion apparatus for a gas turbine engine
US4934145 *Oct 12, 1988Jun 19, 1990United Technologies CorporationCombustor bulkhead heat shield assembly
US4974416 *Feb 27, 1989Dec 4, 1990General Electric CompanyLow coke fuel injector for a gas turbine engine
US4982564 *Dec 14, 1988Jan 8, 1991General Electric CompanyTurbine engine with air and steam cooling
US5117637 *Aug 2, 1990Jun 2, 1992General Electric CompanyCombustor dome assembly
US5123248 *Mar 28, 1990Jun 23, 1992General Electric CompanyLow emissions combustor
US5209067 *Oct 17, 1991May 11, 1993Societe Nationale D'etude Et De Construction De Moteurs D'aviation S.N.E.C.M.A.Gas turbine combustion chamber wall structure for minimizing cooling film disturbances
US5261239 *Feb 25, 1992Nov 16, 1993Societe Nationale D'etude Et De Construction De Motors D'aviationLean premixture combustion-chamber comprising a counterflow enclosure to stabilize the premixture flame
US5274995 *Apr 27, 1992Jan 4, 1994General Electric CompanyApparatus and method for atomizing water in a combustor dome assembly
US5477671 *Jun 3, 1994Dec 26, 1995Mowill; R. JanFor mixing air and fuel for delivery for a gas turbine engine module
US5490388 *Sep 22, 1994Feb 13, 1996Asea Brown Boveri Ltd.Gas turbine combustion chamber having a diffuser
US5572862 *Nov 29, 1994Nov 12, 1996Mowill Rolf JanConvectively cooled, single stage, fully premixed fuel/air combustor for gas turbine engine modules
US5592819 *Mar 8, 1995Jan 14, 1997Societe Nationale D'etude Et De Construction De Moteurs D'aviation S.N.E.C.M.A.Pre-mixing injection system for a turbojet engine
US5613357 *May 29, 1996Mar 25, 1997Mowill; R. JanStar-shaped single stage low emission combustor system
US5628182 *May 23, 1995May 13, 1997Mowill; R. JanStar combustor with dilution ports in can portions
US5638674 *Jul 5, 1994Jun 17, 1997Mowill; R. JanConvectively cooled, single stage, fully premixed controllable fuel/air combustor with tangential admission
US5765363 *Jan 6, 1997Jun 16, 1998Mowill; R. JanConvectively cooled, single stage, fully premixed controllable fuel/air combustor with tangential admission
US5924276 *Jul 15, 1997Jul 20, 1999Mowill; R. JanLow emissions combustor system for a gas turbine
US6021635 *Nov 3, 1997Feb 8, 2000Parker-Hannifin CorporationDual orifice liquid fuel and aqueous flow atomizing nozzle having an internal mixing chamber
US6220034Mar 3, 1998Apr 24, 2001R. Jan MowillConvectively cooled, single stage, fully premixed controllable fuel/air combustor
US6363726Sep 29, 2000Apr 2, 2002General Electric CompanyMixer having multiple swirlers
US6367262Sep 29, 2000Apr 9, 2002General Electric CompanyMultiple annular swirler
US6381964Sep 29, 2000May 7, 2002General Electric CompanyMultiple annular combustion chamber swirler having atomizing pilot
US6418726May 31, 2001Jul 16, 2002General Electric CompanyMethod and apparatus for controlling combustor emissions
US6460344Mar 22, 2000Oct 8, 2002Parker-Hannifin CorporationFuel atomization method for turbine combustion engines having aerodynamic turning vanes
US6474071Sep 29, 2000Nov 5, 2002General Electric CompanyMultiple injector combustor
US6484489May 31, 2001Nov 26, 2002General Electric CompanyMethod and apparatus for mixing fuel to decrease combustor emissions
US6543233 *Feb 9, 2001Apr 8, 2003General Electric CompanySlot cooled combustor liner
US6550251Dec 18, 1997Apr 22, 2003General Electric CompanyVenturiless swirl cup
US6560964Mar 6, 2002May 13, 2003Parker-Hannifin CorporationFuel nozzle for turbine combustion engines having aerodynamic turning vanes
US6564555 *May 24, 2001May 20, 2003Allison Advanced Development CompanyApparatus for forming a combustion mixture in a gas turbine engine
US6609377Jul 31, 2002Aug 26, 2003General Electric CompanyMultiple injector combustor
US6708498Jan 16, 2003Mar 23, 2004General Electric CompanyVenturiless swirl cup
US6883332Apr 23, 2003Apr 26, 2005Parker-Hannifin CorporationFuel nozzle for turbine combustion engines having aerodynamic turning vanes
US6925809Dec 14, 2001Aug 9, 2005R. Jan MowillGas turbine engine fuel/air premixers with variable geometry exit and method for controlling exit velocities
US7779636Apr 6, 2006Aug 24, 2010Delavan IncLean direct injection atomizer for gas turbine engines
US7788927Nov 30, 2005Sep 7, 2010General Electric CompanyTurbine engine fuel nozzles and methods of assembling the same
US7926744Feb 21, 2008Apr 19, 2011Delavan IncRadially outward flowing air-blast fuel injector for gas turbine engine
US7950233Mar 31, 2006May 31, 2011Pratt & Whitney Canada Corp.Combustor
US8128007Dec 17, 2010Mar 6, 2012Delavan IncRadially outward flowing air-blast fuel injector for gas turbine engine
US8146837Dec 17, 2010Apr 3, 2012Delavan IncRadially outward flowing air-blast fuel injection for gas turbine engine
US8156746Jul 20, 2010Apr 17, 2012Delavan IncLean direct injection atomizer for gas turbine engines
US8281597Dec 31, 2008Oct 9, 2012General Electric CompanyCooled flameholder swirl cup
US8607571Sep 18, 2009Dec 17, 2013Delavan IncLean burn injectors having a main fuel circuit and one of multiple pilot fuel circuits with prefiliming air-blast atomizers
US20100199684 *Nov 24, 2009Aug 12, 2010Edward Claude RiceCombustion liner assembly support
EP1106919A1 *Dec 8, 2000Jun 13, 2001General Electric CompanyMethods and apparatus for decreasing combustor emissions
EP2592351A1Oct 30, 2012May 15, 2013Delavan, Inc.Staged pilots in pure airblast injectors for gas turbine engines
WO1988006231A1 *Feb 15, 1988Aug 25, 1988Hi Tech International Lab CompCombustion system for internal combustion engine and combustor used therefor
WO2002088602A1 *Apr 10, 2002Nov 7, 2002Pratt & Whitney CanadaTurbine premixing combustor
Classifications
U.S. Classification60/737, 431/183, 60/751, 60/748
International ClassificationF23R3/14, F23R3/04
Cooperative ClassificationF23R3/04, Y02T50/675, F23R3/14
European ClassificationF23R3/14, F23R3/04