US2866314A

US2866314A - Flame holding device movable between a flameholding position and a streamlined position

Info

Publication number: US2866314A
Application number: US329367A
Authority: US
Inventors: Kurti Alexander
Original assignee: United Aircraft Corp
Current assignee: Raytheon Technologies Corp
Priority date: 1953-01-02
Filing date: 1953-01-02
Publication date: 1958-12-30
Anticipated expiration: 1975-12-30

Description

Dec. 30, 1958 KURT] 2,866,314

FLAMEHOLDING DEVICE MOVABLE BETWEEN A FLAMEHOLDING POSITION AND A STREAMLINED POSITION Filed Jan. 2, 1953 INVEN TOR ALEXANDER KURT/ FLAME HOLDING DEVICE MOVABLE BETWEEN A FLAMEHOLDLNG POSITION AND A STREAM- LINED POSITION Alexander Kurti, North Woodbury, Conn., assignor to United Aircraft Corporation, East Hartford, Conn a corporation of Delaware Application January 2, 1953, Serial No. 329,367

10 Claims. (Cl. 6035.6)

This invention relates to a flame holding apparatus and more particularly to the type used in an afterburner of an aircraft engine.

An object of this invention is to provide a flameholder with a retractable portion which will move between a position making the flameholder streamlined, for use when there is no afterburning, to a position making the downstream end of the flameholder a blunt end for use when there is afterburning to effect a reduction of velocity thereby stabilizing combustion at this point.

Another object of this invention is to provide a flameholder which will prevent blowout at the operating velocities of flow which pass through the afterburner. Since the speed of flame propagation is less than the stream velocity, it is necessary to provide a region of low relative velocity of suificient size to establish a flame. When this flame is extinguished it is referred to as a blowout.

A further object of the invention is to provide a flameholder which will have a minimum of pressure loss thereover during non-afterburning.

Further objects and advantages will be apparent from the following specification and drawings.

Fig. 1 is a view of a jet engine and afterburner combination with the greater portion of the engine in outline form and with the remainder of the engine and the afterburner in cross section.

Fig. 2 is an enlarged view of the lower part of the flameholder as shown in Fig. 1 with its actuating mechanism. Fig. 3 is a view taken along the line 3-3 of Fig. 2. Fig. 4 is a view taken alongthe line 44 of Fig. 2.

With reference to Fig. l, the turbojet engine 2 shown is a centrifugal type having its compressor 7 driven by a turbine 4. Combustion chambers 5 therein deliver air from the compressor to the turbine. An afterburner 6 is attached to the turbine outlet to provide a means of increasing the thrust.

Air is directed into the engine to the compressor. Compressed air discharging from the compressor passes to the turbine 4 through combustion chambers where it is mixed with fuel. Fuel is delivered to said engine through conduit 8. The fuel-air mixture is initially ignited within the combustion chambers by spark igniter 10. It is to be understood that any fuel supply means and ignition means for an engine may be used.

From the turbine 4, the gases pass around a cone 12 into the diffuser section 14 of the afterburner. When the afterburner is operating, fuel is discharged into these gases from a plurality of fuel nozzles 16, connected to fuel conduit 17, located in diffuser 14. Since the gases leaving the turbine 4 contain considerable unburned oxygen, the additional fuel introduced by fuel nozzles 16 provides a combustible mixture which may be initially ignited Within the combustion chamber 18 by a spark igniter 28. Here again, for the afterburner, it is to be understood that any type of fuel supply means and ignition means for an afterburner can be used. The burning of this combustible mixture is stabilized in the combustion chamber 18 of the afterburner by a flameholder 22. A flameholder accomnite States Patent 2,856,314 Patented Dec. 30, 1958 plishes this by providing an area in which the velocities are maintained at a value below that at which blowout occurs. The burned bases discharge from the engine through the nozzle 24 whose area can be varied.

The variable nozzle 24 operates between a minimum opening for engine operation without afterburning and a maximum opening for operation of the engine with afterburning. The nozzle actuating system as shown consists of a cylinder 26, a piston 28, a nozzle control rod 30 and a piston rod 32. The variable nozzle 24 is opened or closed by admitting an actuating pressure to one side of piston 28 or the other through

conduits

34 or 36. It can be seen that if a pressure is admitted through conduit 34 and valve 40 to the right side of pistons 28, and the left side of pistons 28 are vented, the nozzle 24 will be moved in a nozzle opening manner, and if an operating pressure is admitted through conduit 36 and valve 38 to the left side of pistons 28, and the right side of pistons 28 are vented, the nozzle 24 will be moved in a closing direction. While the selection and admission of this actuating pressure and venting can be performed manually, a nozzle control which will perform such function automatically is shown and claimed in U. S. application Serial No. 196,424 filed November 18, 1950, now Patent No. 2,715,311.

With reference to Fig. 2, the flameholder 22 is formed of two parts 42 and 44. The part 42 consists of an annular ring substantially fixedly supported in the combustion chamber of the afterburner by a streamlined strut structure 46. This structure consists of a center section 48 and outer sections 50. These outer sections are mounted to allow for radial expansion in a manner to be hereinafter described. The part 42 is hollow, being U-shaped in cross section, with its downstream end open and is formed having a cross section of the forward part of a through are below a value suflicient to cause blowout.

In Fig. 2 the rearward position of part 44 is shown by the solid lines while the forward position of part 44 is indicated by the dot and dash lines in which the spaces between the legs of the U and the wedge part 44 constitute reentrant areas for effectively producing the desired turbulence.

Part 44 is actuated by a plurality of mechanisms spaced [around the afterburner 6. Each mechanism consists of three main parts: an actuating device 52, an attaching means 54, and a connecting linkage 56.

The actuating device 52 consists of a cylinder 58, a piston 60 and a piston rod 62. The rearward end of the cylinder 58 is pivotally mounted. A lug 64 extends rearwardly from the rear end of cylinder' 58 and has a hole 66 therethrough. A bracket 68 is fixedly mounted on the afterburner 6 and has an internally threaded bore 78. A bolt 72 passes through hole 66 and is threadably engaged in bore 70. Bolt 72 may be fixed against rotation by any means desired such as a cotter pin at 72'.

The free end of piston rod 62 has fixed thereon a bifurcated portion 74 with a hole passing through both of the tines for a purpose to be described later. The cylinder 58 has an opening 76 at its forward end and an opening 78 at its rearward end. Opening 76 is connected to conduit 36 by a conduit 80 having a valve 82 located therein and opening 78 is connected to conduit 34 by a conduit 84 having a valve 86 locatedtherein. It can be seen that if a pressure is admitted through conduits'34 and 84 and valve 86 to the right side of pistons 60 and the left sideofpistons 60, are vented, the pistons and their respective piston rods 62"will be moved to the left, and-if an operating pressure is admitted through conduits 36' and 80 and valve. 82 to'the left side of pistons 60 andthe right side of pistons 60 are vented, the pistons and'their respective piston rods 62 will be moved to the right. While the selection and admission of the actuating pressure and connection to drain can be performed manually, an automatic control can perform such function as referred to above.

Attaching means 54 consists of a flat plate 88 fixed to the flat forward-portion of part 44011; to'which is fixed two members 90 forming abifurcated bracket. These members have integralreinforcing ribs 92=to add support to the structure. A hole 94.is located attire forward endof each of'the members 90 for-a purpose to be disclosed hereinafter.

The connecting linkage 56 connects the actuatingdevice 52 to the attaching means 54. This connecting linkage 56 consistsof a rod 87 mounted for rotation at one end in part 42 of the flameholder 22 and at the other'end in the wall of afterburner 6. The mounting in part 42 consists of two bearing members 96 and 98 which are fixed therein and coaxially positioned. The interior diameter of bearing 96 is sized so as to receive the diameter of rod 87 and the interior diameter of bearing 93 is sized so as to receive the necked down end portion 100 of rod 87. The mounting in the wall of the afterburner consists of one bearing member 102 whichis fixed to a pad 104 men annular reinforcing plate 106 which extends around the afterburner. These bearings 102 also extend into the interior of the afterburner to form a support for the outer sections 50 of the strut structure 46. This is accomplished by having a plate 108 fixed to the outer end of the sections 50 with a bearing receiving member 110 therein. In the construction a space 112 is left to allow for radial expansion,

Rod $7 is attached at its end within part 42 to the bracket on the forward portion of part 44 by a lever 114. One end of lever 114 is fixed to rod 87 between the free ends of bearings 96 and 98 by any means desired such as by a pin 113. The other end of lever 114 is positioned between the free ends of the bracket formed on the forward portion of part 44 and is connected thereto by a pin 116 which passes through the end of said lever arm and the holes 94 located at the forward end of each of the members 90. This pin 116 permits relative movement at this point and is maintained in place by any means desired such as by cotter pins. A spacer 118 is located on each side of arm 14 around said pin 116 and is weldedto member 90 to provide bearing area.

The end of rod 87 outside of said afterburner is connected to the bifurcated portion 74 of the actuating device 52 by a lever arm 120. This lever arm 120 is fixed to the outer free end of rod 87 by any means desired such as by a pin 122. The other end of lever 120 is positioned between the tines of the bifurcated portion 74 and has a hole therein which is aligned with the holes in said tines. A bolt 124 passes through said holes permitting relative movement at this point.

Operation When the engine is operating without afterburning, the position of the flameholder 22 and nozzle.24 along with their respective operating mechanisms will be in their positions as shown in Fig. 1. When the engine is functioning in this manner, with

valves

38, 40, 82 and 86 open, an actuating pressure is directed through conduit 36to the left side of cylinder 26 and through conduit 30 to the left side of. cylinder 58. At the same time the right sides of. cylinders 26 and 58 are vented. This places the flameholder 22 in its streamlined position, that 4 is with part 44 thereof in its rearward position, so that itspresence in the airstream produces a minimum ofturbulence and pressure loss.; This action also places the nozzle 24 in its closed position.

Now, when engine operation is desired with aftcrburning, an actuating pressureis directed through conduit 34 to the right side of cylinder 26 and through conduit 84 to theright side of cylinder 58. At the same time the left sides of cylinders 26 and 58 are vented. This places flameholder 22 in its flame holding position, that is with part 44 thereof in its forward position, so that part 42. effects a reduction of velocity thereby stabilizing combustion within the afterburner. This action also places the nozzle 24 in its open position.

While a manual system can be used to transfer the actuating pressure and venting to either

conduit

34 or 36 it is to be understood that an automatic means may be provided to perform this operation.

In the operation described above it has been considered that theflameholder 22 and nozzle 24 are actuated simultaneously. However, if it is desired to have either the flameholder or nozzle operate first this can be controlled by the use of the

valves

38, 40, 82 and 86. For example, if it is desirous to have the flameholder operated before the nozzle, the

valves

38 and 40 may be closed leaving valves 82 and 86 open so that when the

conduits

34 and 36 have their connections interchanged, that is from actuating pressure to drain which ever may be the case, the fiameholder will be actuated alone and after a predetermined time interval the

valves

38 and 40 can be opened permitting the new interchanged pressures to be admitted'to the cylinders 26 thereby actuating the nozzle.

Here again while this has been shown as a manual operation, automatic means may be used to provide such a delay in either the actuation of the fiameholder-or nozzle. For example, the valves can be used as variable restrictions delaying the, action to one cylinder or the other. If a fixed relation of delayed action is desired,

a fixed restriction may be placed in the proper conduitbe evident to those skilled in the art that the invention is capable of various modifications and adaptations within the scope of the appended claims.

I claim:

1. In combination, a combustion chamber through which gases pass at high velocities, an annular flameholder mounted in said chamber, said fiameholder comprising'a member having two annular parts, a forward part and a rearward part, said forward part having a leading edge, surfaces extending aft and diverging from the leading edge, said surfaces subsequently converging and terminating in spaced relation to each other, said rearward part having its forward end located within the rearward end of said forward part, surfaces extending aft from said forward end of said rearward part and converging and terminating adjacent each other to form a trailing edge, means for placing the rearward part of said flameholder substantially completely within said forward part such that the converging surfaces on the rearward part are laterally spaced from the adjacent terminating surfaces of the forward part.

2. In combination, a combustion chamber through which gases pass at high velocities, an annular flameholder mounted in said chamber, said flameholder comprising a member having two annular parts, a forward part and a rearward part, said forward part having a lead-' ing edge and surfacesextending aft and diverging from the leading edge, said surfaces subsequently terminating in spaced relation to each other, said rearward part having its forward end located within the rearward end of said forward part, surfaces extending aft from said forward end of said rearward part and converging and terminating adjacent each other to form a trailing edge, and means for placing the rearward part of said flameholder substantially compeltely within said forward part such that the entire area of the forward part at the trailing edge functions as a. flameholder.

3. In combination, a combustion chamber through which gases pass at high velocities, an annular liameholder mounted in said chamber, said flameholder comprising a member having two annular parts, a forward part and a rearward part, said forward part having a circular leading edge and surfaces extending aft and diverging from the leading edge, said surfaces subsequently terminating in spaced relation to each other, said rearward part having its forward end located within the rearward end of said forward part, surfaces extending aft from said forward end of said rearward part and converging and terminating adjacent each other to form a circular trailing edge, and means Within said forward part and connected to said rearward part for moving the rearward part of said flameholder forwardly as a unit into a position substantially within said forward part.

4. In combination, a combustion chamber through which gases pass at high velocities, an annular flameholder mounted in said chamber, said flameholder comprising a member having two annular parts, a forward part and a rearward part, said forward part having a circular leading edge and surfaces extending aft and diverging from the leading edge, said surfaces subsequently converging and terminating in spaced relation to each other, said rearward part having its forward end located within the rearward end of said forward part and having a radial dimension substantially equal to the space between the spaced apart ends of said surfaces, said rearward part also including surfaces extending aft from said forward end of said rearward part and converging and terminating adjacent each other to form a circular trailing edge, and means within said forward part and connected to said rearward part for moving the rearward part of said flameholder forwardly as a unit into a position substantially within said forward part with the converging surfaces of the rearward part spaced radially from the ends of the surfaces on the forward part.

5. In combination, a combustion chamber through which gases pass at high velocities, a flameholder mounted in said chamber, said flameholder comprising a member having two parts, a forward part and a rearward part, said forward part having a leading edge, surfaces extending aft and diverging from the leading edge, said surfaces subsequently terminating, said rearward part having its forward end located within the rearward end of said forward part, surfaces extending aft from said forward end of said rearward part and converging and terminating adjacent each other to form a trailing edge, means for placing the aft part of said flameholder substantially within said forward part, said last named means including a bracket fixed to the forward end of the rearward part of said flame holder and located within said forward part, a lever pivotally mounted at one end to and within the forward part of said flameholder, the free end of said lever being connected to said bracket, and means external to the combustion chamber for moving said lever thereby moving the rearward part of said flameholder axially in relation to the forward part.

6. In combination, a combustion chamber through which gases pass at high velocities, an annular fiameholder mounted in said chamber, said flameholder comprising a body having two annular parts, one part being substantially U-shaped in cross section with the open end thereof facing downstream and the other part being a movable wedge-shaped piece adapted to be positioned within the U-shaped part and movable to a position to form with said part a streamlined body.

7. In combination. a combustion chamber through which gases pass at high velocities, an annular flameholder mounted in said chamber, said flameholder comprising a body having two annular parts, one part being substantially U-shaped in cross section with the open end thereof facing downstream and the other part being a movable wedge-shaped piece adapted to be positioned within the U-shaped part to form reentrant areas between the legs of the U and the wedge shaped piece and movable to a position to form with said part a streamlined body, and means accessible externally of said combustion chamber for actuating said movable wedge.

8. In combination, a combustion chamber through which gases pass at high velocities, an annular flameholder mounted in said chamber, said flameholder comprising a body having two annular parts, one part being substantially U-shaped in cross section with the open end thereof facing downstream and the other part being a movable wedge-shaped piece adapted to be positioned within the U-shaped part and movable axially to a position to form with said part a streamlined body, means accessible externally of said combustion chamber for actuating said movable wedge, said last named means including a bracket fixed to the forward end of said wedgeshaped piece, a lever pivotally mounted at one end in the U-shaped part, the free end of said lever being connected to said bracket, and means for moving said lever thereby moving the wedge-shaped piece axially in relation to said U-shaped part.

9. In combination, a combustion chamber through which gases pass at high velocities, an annular flameholder mounted in said chamber, said flameholder comprising a body having two annular parts, one part being substantially U-shaped in cross section with the open end thereof facing downstream and the other part being a movable wedge-shaped piece adapted to be positioned within the U-shaped part and movable axially to a position to form with said part a streamlined body, means accessible externally of said combustion chamber for actuating said movable wedge, said last named means including a bracket fixed to the forward end of said wedge-shaped piece, a lever pivotally mounted at one end in the U-shaped part, the free end of said lever being connected to said bracket, a shaft fixed at one end to the pivot of said lever and having its other end extend to the exterior of said combustion chamber, a second lever fixed at one end to the end of said shaft extending externally of said combustion chamber, and means for actuating the free end of said second lever.

10. In combination, a combustion chamber through which gases pass at high velocities, -a nozzle controlling the opening at the rearward end of said combustion chamber, a cone having its apex projecting into the forward end of said combustion chamber forming an annular passageway for the flow of gas into said combustion chamber, a flameholder mounted in said combustion chamber and axially spaced downstream from said cone, said flameholder comprising an annular streamlined body having two parts, the forward part of said streamlined body forming the forward part of said flameholder and being of flame holding shape, the rearward part of said streamlined body forming the rearward part of said flameholder and being of substantially wedge shape, the forward part of said flameholder having an opening therein to receive the rearward part of said flameholder for axial movement therein, said rearward part of said streamlined body being mounted for axial movement with respect to said forward part such that said rearward part may be positioned within said forward part of said streamlined body to provide a flameholding shape.

(References on following page) Referenees Cited irpthe file of, thispatent UNITED STATES PATENTS,

Price Nov. 8, 1949 Servanty Nov. 20, 1951 Laucher "May 12, 1953 8 Brown Mar. 23, 1954 Oulianofi Dec. 14, 1954 Johnson Nov. 27, 1956 FOREIGN PATENTS France Jan. 20, 1947