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Publication numberUS2799991 A
Publication typeGrant
Publication dateJul 23, 1957
Filing dateMar 5, 1954
Priority dateMar 5, 1954
Publication numberUS 2799991 A, US 2799991A, US-A-2799991, US2799991 A, US2799991A
InventorsConrad Earl W
Original AssigneeConrad Earl W
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Afterburner flame stabilization means
US 2799991 A
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Description  (OCR text may contain errors)


46 0 INVENTOR 'EARL n. com/w BY MJM ATTORNEYS United States Patent AFTERBURNER FLAME STABILIZATION MEANS Earl W. Conrad, Berea, Ohio Application March 5, 1954, Serial No. 414,520

4 Claims. (Cl. 6039.72)

(Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of American for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to improvements in gas reaction engines, and particularly to a device for providing a strong, stable pilot for a jet engine afterburner.

An object of this invention is to provide means for establishing a very strong, stable piloting action for use in turbojet engine afterburners under conditions, such as extremely low pressure or high velocity, at which present afterburner designs will not operate with good efliciency.

Another object of the invention is to provide an afterburner pilot burner which serves as a strut for mechanical support in the engine, and which taps a portion of the extremely hot gas at the engine turbine inlet for combining with fuel and igniting by shock or auto ignition whereby there is always present a dependable pilot for the engine afterburner.

Other objects and features will become apparent in following the description of the illustrated form of the invention.

In the drawing:

Fig. 1 is a fragmentary schematic view of a turbo jet engine having the invention therein.

Fig. 2 is an enlarged sectional view taken on the line 22 of Fig. 1.

Fig. 3 is a perspective view of a typical embodiment of the invention, parts being broken away to show internal details.

The axial flow, turbo jet engine includes an engine casing 12 in which there is a core structure having a diffuser inner body 14. An afterburner 15 is schematically illustrated in casing 12, as is the turbine 18, these elements of the engine being disposed in their usual functional arrangement.

At very low pressure-high velocity conditions of operation, afterburners do not operate satisfactorily. In order to correct this, the invention provides means assuring stable primary burning, which is a requirement for stable operation of the afterburner as a whole. Strut is one instrumentality by which the invention may be practiced, and it consists of an outer shell 22 in which there is an inner shell 24 serving as a gas conductor. Outer shell 22 is secured to the engine casing 12 and the diffuser body 14, holding the latter assembled in shell 22. Any number of struts 20 may be used in an engine, depending on the demands of the particular engine.

As seen in Fig. 1, a by-passpassageway 26 feeds a small amount of the extremely hot gas from the region in advance of turbine 18 to the inner shell 24, the gas entering the chamber 28 through discharge opening 30 in gas conductor 24. Chamber 28 is formed by the spaced walls of shells 22 and 24, and the upper and lower spacers 32 which help to hold the shells assembled. There is a discharge opening 36 at the aft end of shell 22, and it is in communication with chamber 28 through a convergingice diverging passage 38 on each side of strut 20 and bounded by the walls of the inner and outer shells 24 and 22 respectively.

Means are provided for delivering fuel to the gas as it passes through strut 20, a suggested arrangement being shown in Fig. 1 where a line 40 is taken from the afterburner fuel supply system and led into the strut. The fuel line 40 is connected to two ducts 42 and 44, one being fixed to each side of inner shell 24. A series of orifices 46 are formed in the inner shell walls, opening into the interior of ducts 42 and 44 so that fuel may be delivered through the inner shell walls and into passage 38 to admix with the gas passing therethrough.

There is a grid 48 in the discharge opening 36 comprised of a series of plates placed parallel to the direction of the airstream, and a plurality of generally V-shaped gutters 50 carried by the outer shell 22. The gutters are located at opening 36, extend rearwardly of strut 20, and then diverge. The purposes of grid 48 and gutters 50 will be stated subsequently.

In operation, a portion of the extremely hot gas at the turbine inlet is by-passed around turbine 18 through passage 26 and introduced into gas conductor 24 which is in registry with passage 26. The gas flows through opening 30, chamber 28, passageway 38, and finally through discharge opening 36. A portion of the afterburner fuel is injected into the hot gas as it passes through the passageway 38, and it ignites by auto ignition, thereby avoiding the need for any other ignition device. Excellent combustion in the afterburner region is assured in View of the high dependability of the hot shot pilot system which ignites fuel by auto ignition at the same temperature but at much higher velocities than those existing in the strut 20.

The gutters 50 serve to stabilize the combustion of the main afterburner fuel not only by the mechanism of recirculation but also by the spread of the primary burning from the strut along the sheltered regions provided by the gutters.

The illustrated embodiment may exploit the high reaction rates possible with shock ignition. The passage 38 is in the form of a converging-diverging nozzle which accelerates the gas flow sufticiently to form a standing shock. The flame would seat on this standing shock front. The low solidity grid 48 (i. e., a series of parallel plates having a low proportion of the total frontal area thereof taken up by the plates) is preferably placed adjacent the trailing edge of airfoil-shaped conduit 24 and is intended to produce bow waves (shock waves ahead of the plates of the grid 48 which would intersect and reinforce, increasing the temperature Within the shock. Grid 48 is optionally used, regardless of whether there is auto ignition or shock ignition in the engine afterburner region.

It is understood that various modifications may be made without departing from the following claims.

What is claimed is:

1. In combination, an engine casing, a diffuser inner body, struts holding said casing and said body in spaced assembled relationship, at least one of said struts comprising a shell having a rounded leading edge, an airfoilshaped conduit within said shell, means connecting said conduit to a source of high-temperature gas, outlet means in said conduit directed toward the interior of said leading edge, pipe means within said conduit, said pipe means being connected to a source of fuel, outlet means for said fuel in said pipe and in said conduit downstream of said first mentioned outlet means, and an opening in said strut opposite said leading edge.

2. The apparatus of claim 1, and grid means in said strut opening adjacent the trailing edge of said airfoilr a "4 a shaped conduit to produce intersecting and reinforcing 1 References Cited in the file of this patent bow Waves in the region between said shell and said con- UNITED STATES PATENTS duit. a

3. Apparatus as in claim 1, said one strut extending 2482505 Plerce Sept 1949 'rearwardly fiom said leading edge and forrniuga' cdn- 5 2673445 Bruckmann 1954 verging-diverging nozzle with said airfoil l'shafied'conduit. 2674845 Pouchot 1954 4. The apparatus of claim 1, and a grid in said strut opening, said grid comprising a series ofpl ates parallel to FOREIGN PATENTS V a 7 r 499,468 Belgium Mar. 16, 1951 the direction of the airstream. V I

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2482505 *Sep 13, 1947Sep 20, 1949Wright Aeronautieal CorpMechanism providing a ram jet engine with a pilot flame and with a drive for its auxiliary equipment
US2673445 *Jun 21, 1949Mar 30, 1954Bruckmann Bruno WTurbojet and rocket motor combination with hot gas ignition system for nonself-reaction rocket fuels
US2674845 *May 2, 1951Apr 13, 1954Pouchot Walter DDiffuser apparatus with boundary layer control
BE499468A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2935847 *Nov 18, 1957May 10, 1960United Aircraft CorpFlow control means for use with flameholders and flamespreaders
US2944398 *Oct 20, 1954Jul 12, 1960Lockheed Aircraft CorpCombustion chamber for jet propulsion motors
US2944399 *May 31, 1956Jul 12, 1960Gen ElectricAfterburner combustion means
US3300976 *Jan 27, 1965Jan 31, 1967Rolls RoyceCombined guide vane and combustion equipment for bypass gas turbine engines
US3479823 *Jun 27, 1967Nov 25, 1969Rolls RoyceCombustion apparatus
US4051670 *May 30, 1975Oct 4, 1977United Technologies CorporationSuction vent at recirculation zone of combustor
US4259839 *Jun 18, 1979Apr 7, 1981Societe Nationale D'etude Et De Construction De Moteurs D'aviationFlame holder devices for combustion chambers of turbojet engine afterburner tubes
US4438626 *Sep 11, 1981Mar 27, 1984General Electric CompanyApparatus for attaching a ceramic member to a metal structure
US4490973 *Apr 12, 1983Jan 1, 1985The United States Of America As Represented By The Secretary Of The Air ForceFlameholder with integrated air mixer
US4592200 *Sep 5, 1984Jun 3, 1986Societe Nationale D'etude Et De Construction De Moteurs D'aviation - S.N.E.C.M.A.Turbo-jet engine afterburner system
US4751815 *Aug 29, 1986Jun 21, 1988United Technologies CorporationLiquid fuel spraybar
US4887425 *Mar 18, 1988Dec 19, 1989General Electric CompanyFuel spraybar
US4893468 *Nov 30, 1987Jan 16, 1990General Electric CompanyEmissions control for gas turbine engine
US5020318 *Nov 5, 1987Jun 4, 1991General Electric CompanyAircraft engine frame construction
US5076062 *Nov 5, 1987Dec 31, 1991General Electric CompanyGas-cooled flameholder assembly
US5396763 *Apr 25, 1994Mar 14, 1995General Electric CompanyCooled spraybar and flameholder assembly including a perforated hollow inner air baffle for impingement cooling an outer heat shield
US5685142 *Apr 10, 1996Nov 11, 1997United Technologies CorporationGas turbine engine afterburner
US6971239 *May 13, 2003Dec 6, 2005United Technologies CorporationAugmentor pilot nozzle
US7251941Mar 10, 2004Aug 7, 2007General Electric CompanyAblative afterburner
US7565804 *Jun 29, 2006Jul 28, 2009General Electric CompanyFlameholder fuel shield
US7581398 *Jun 29, 2006Sep 1, 2009General Electric CompanyPurged flameholder fuel shield
US20100050643 *Sep 4, 2008Mar 4, 2010United Technologies Corp.Gas Turbine Engine Systems and Methods Involving Enhanced Fuel Dispersion
EP0315485A2 *Nov 4, 1988May 10, 1989General Electric CompanyGas-cooled flameholder assembly
U.S. Classification60/749, 60/765
International ClassificationF23R3/20, F23R3/02
Cooperative ClassificationF23R3/20
European ClassificationF23R3/20