US2707372A

US2707372A - Afterburner apparatus for turbo jet engines having movable flame holder means

Info

Publication number: US2707372A
Application number: US753901A
Authority: US
Inventors: Ii Frank A Cleveland
Original assignee: Lockheed Aircraft Corp
Current assignee: Lockheed Corp
Priority date: 1947-06-11
Filing date: 1947-06-11
Publication date: 1955-05-03
Anticipated expiration: 1972-05-03

Description

May 3, 1955 F. A. CLEVELAND ll 2,707,372

AFTERBURNER APPARATUS FOR TURBO JET ENGINES HAVING MOVABLE FLAME HOLDER MEANS 3 Sheets-Sheet 1 Filed June 11, 1947 INVENTOR FRANK A. CLEVELANDII Agent y 1955 F. A. CLEVELAND u 2,707,372

AFTERBURNER APPARATUS FOR TURBO JET ENGINES HAVING MOVABLE FLAME HOLDER MEANS Filed June 11. 1947 3 Sheets-Sheet 2 77MEO arr/raw 47 47 45 48 J V 42 o fi- IIILIW INVENTOR FRAN K A. CLEVELAN DJI Agent May 3, 1955 F. A. CLEVELAND AFTERBURNER APPARATUS FOR TURBO JET ENGINES HAVING MOVABLE FLAME HOLDER MEANS 3 Sheets-Sheet I5 Filed June 11. 1947 INVENTOR FRANK A. CLEVELANDIII United States Patent 0 AFTERBURNER APPARATUS FOR TURBO JET ENGmES HAVING MOVABLE FLAME HOLDER MEANS Frank A. Cleveland II, Pasadena, Calif., assiguor to Lockheed Aircraft Corporation, Burbank, Calif.

Application June 11, 1947, Serial No. 753,901

23 Claims. (Cl. 60-35.6)

This invention relates to powerplants of the reactive jet propulsion type and relates more particularly to afterburner apparatus for increasing or augmenting the propulsive thrust of such powerplants.

One of the most difficult problems accompanying the propulsion of aircraft with turbo jet engines is the attaining of sufficient acceleration of the aircraft at low speeds; for example when taking off. Since the net thrust of a turbo jet powerplant is substantially constant at all forward speeds, there is an insufficiently high acceleration to take the airplane off the ground within reasonable takeoff distances. Rapid acceleration during flight is also highly important in combat and emergency maneuvers of military aircraft. Afterburning or tail pipe burning in which supplemental fuel is introduced into the gas stream at a point or points in downstream relation to the turbine has been suggested to obtain the increased thrust and acceleration.

It is an object of the present invention to provide after burning apparatus for augmenting the thrust of a turbo jet powerplant which is characterized by a particularly effective flame arrester or flame holder which promotes a more eflicient combustion of the afterburner fuel and which prevents upstream advancement of the afterburner front. The flame arrester, which may also be termed a flame holder, flame seat, or flame grid, serves to create distributed turbulence in the high velocity gas stream to bring about a thorough mixing of the supplemental fuel with the air and gas of the turbine exhaust and also increases the velocity of the gas stream in a manner to prevent the flame front of the burning supplemental fuel from advancing upstream to the supplemental fuel injectors.

It is another and particularly important object to provide an apparatus of the character referred to that offers a minimum of resistance or drag to the flow of the turbine exhaust gases when the powerplant is in normal operation unassisted by afterburner thrust augmentation. In accordance with the invention the flame arrester is movable between a retracted or inactive position and an operative position. When the flame holder of certain embodiments of the invention is in the inactive position, it is located and arranged to offer a minimum of resistance to the flow of the gases. In other applications and forms of the invention the flame arrester is entirely withdrawn from the path of the gases when moved to the inactive position and, therefore, offers no resistance to normal gas flow. During ordinary powerplant operation when no fuel is being supplied to the afterburner the flame holder is in the retracted or inactive position where it does not appreciably reduce the overall thrust output of the engine.

A further object of the invention is to provide an afterburner apparatus of the type mentioned embodying simple dependable means for mounting the flame arrester or holder for ready movement between the operative and inactive positions.

A still further object of the invention is to provide an afterburner apparatus of the class described in which the flame holder is coordinated with the other elements of the afterburner to be automatically moved to the active position when the afterburner is put into operation and to be retracted or brought to the inactive position when afterburner operation is terminated. The invention provides a coordinated control in which the fuel supply to the afterburner, the ignition means for the afterburner and the flame arrester are simultaneously or sequentially controlled. In addition, a manually operable overriding safety control means is provided for the flame holder so that the engine operator or flight engineer may move the flame arrester to any selected position irrespective of the position of the other elements of the apparatus.

Other objects and features of the invention will become apparent from the following detailed description of typical embodiments of the invention throughout which description reference will be had to the accompanying drawings in which:

Figure l is a side elevation of a turbo powerplant embodying the afterburner apparatus of the invention, the broken lines illustrating the two positions of the flame holder;

Figure 2 is an enlarged fragmentary perspective view of the afterburner showing the flame holder in its operative position;

Figure 3 is an enlarged fragmentary sectional View taken as indicated by line 3-3 in Figure 2 illustrating the fairing of the flame holder;

Figure 3A is an enlarged transverse sectional view as indicated by line 3A-3A in Figure 2 of a. grid member of the flame holder;

Figure 4 is a fragmentary longitudinal sectional view of the afterburner taken as indicated by line 4-4 on Figure 1 showing the flame holder in its idle position;

Figure 5 is a diagrammatic view illustrating the control system for the flame holder and fuel supply;

Figure 6 is an enlarged fragmentary sectional view taken as indicated by line 6-6 on Figure 5;

Figure 7 is a view similar to Figure 4 illustrating another embodiment of the invention, taken substantially as indicated by line 7-7 on Figure 8;

Figure 8 is a fragmentary transverse sectional view of the apparatus illustrated in Figure 7, illustrating the means for operating the flame holder;

Figure 8A is an enlarged fragmentary sectional view taken as indicated by line 3A-8A on Figure 8;

Figure 9 is a fragmentary longitudinal sectional view illustrating still another embodiment of the invention with broken lines indicating the idle position of the flame holder;

Figure 10 is a transverse sectional view taken substantially as indicated by line 10-10 on Figure 9, showing the flame holder in the retracted position; and

Figure 11 is a fragmentary perspective view of the hinge mounting of the flame holder of Figures 9 and 10.

In Figures 1 to 6 inclusive, I have illustrated one form of the invention incorporated in a more or less conventional internal combustion turbo powerplant of the type employed for the propulsion of aircraft. This invention is not primarily concerned with the details of the powerplant per se and such details are, therefore, being omitted. The turbo engine, as illustrated in Figure 1, includes the turbine 16 driven by the air and gases of combustion received from the combustor tubes 11 which in turn receive the compressed air from the usual compressor or compressors. The ram air is admitted at the forward end of the engine while the turbine exhaust gases are discharged through the turbine exhaust nozzle 12, which continues rearwardly from the turbine 10.

An afterburner combustion chamber is arranged to receive the turbine exhaust gases from the nozzle 12 and comprises an elongate tail pipe or tube 13. The afterfor discharging the heated high velocity gases in the form of a reactive propulsion jet for propelling the aircraft.

Means is provided for introducing supplemental fuel in the afterburner combustion chamber to increase the thermal energy of the turbo exhaust gases and thereby increase the thrust output of the engine. In accordance with the broader aspects of the present invention any suitable means may be incorporated to inject the afterburner fuel. In the drawings I have shown a fuel supply or manifold pipe delivering fuel under pressure to a plurality of spaced distributor tubes 16. The tubes 16 enter the afterburner tube 13 and may extend transversely across its interior. Suitable jets or ports 1.7 in the distributor tubes 16 discharge the fuel into the stream of the turbine exhaust gases flowing through the afterburner. The fuel injecting means is preferably arranged so as to introduce the fuel into the forward or upstream por- L tion of the afterburner 13.

The apparatus also includes means for igniting the fuel in the afterburner. This may comprise an electrical spark plug or glow plug 13 mounted on the wall of the afterburner tube and presenting a resistance coil or the admixture of the afterburner fuel with the air in the gas 0 stream and where it increases the velocity of the stream to a suflieient degree to prevent the flame front of the afterburner from progressing upstream to the fuel injectors 16. In Figures 1 to 6 inclusive the flame holder includes a ring 21 of somewhat smaller diameter than the afterburner tube 13. The ring 21 is adapted to move within the tube 13 with sufficient clearance to allow a boundary layer of relatively cool gases to flow along the surface of the tube without interference. This gas layer serves to partially insulate the tube 13 from the high temperature gas flow. The flame holder further includes a grid arranged across the interior of the ring 21 to be in the path of the turbine exhaust stream when the flame holder is in its operative position. The grid may vary considerably in configuration and construction without departing from the invention. In the case illustrated, the grid comprises a series of substantially parallel continuous members 22 extending across the interior of the ring 21 and shown as upright elements in Figure 2. Shorter grid members 23 extend between and connect the spaced vertical members 22. The ends of the vertical members 22 are fixed to the ring 21 while the ends of the horizontal members 23 are secured to the adjacent members 22 and the ring 21. As best shown in Figure 2, the

members

22 and 23 constitute a screen or grid defining square or rectangular windows or spaces. The

grid members

22 and 23 and the ring 21 are preferably formed of heat and corrosion resistant metal to withstand the high temperatures to which the flame holder is subjected. I prefer to make the

grid members

22 and 23 substantially V shaped in transverse cross section as shown in Figure 3A, and arrange them so that their apices face upstream and their open sides face downstream when the flame holder is in. its active position.

In the embodiment of the invention shown in Figures 1 to 6 inclusive, the flame holder 20 is supported for angular or pivotal movement about an axis that is diamet rical of the afterburner tube 13. Pivots .or stub sha-fts 24 extend from the periphery of the ring 21 and pass outthe plate.

wardly through diametrically opposite openings in the wall of the tube 13. Heat resistant packing glands 25 are preferably arranged at the openings to seal about the shafts 24 and the portions of the shafts which continue outwardly from the glands are carried in suitable journals or bearings 26. The bearings 26 are in turn mounted on brackets 27 to be spaced from the wall of the tube 13 which may become heated to a substantial temperature.

The flame holder 20 mounted as just described is spaced some distance downstream from the fuel injectors 16 as shown in'Figures l, 2 and 4. The pivoted flame holder 20 is movable between the idle position shown in Figure 4 where it occupies a plane parallel with the longitudinal axis of the tube 13 and the active position of Figure 2 where it occupies a plane substantially perpendicular to said axis so-that its grid 2223 is effective in preventing upstream advancement of the afterburncr flame and in promoting eflicient consumption of the afterburner fuel. The invention provides a shroud or fairing 29 on the periphery of the ring 21 to reduce the drag or interference of the flame holder with the turbo exhaust stream when the holder is in its idle position. The fairing 29 extends for approximately 180 along the edge of the ring 21 that faces upstream when the flame holder is in the inactive position of Figure 4. The resistance reducing fairing 29 may be a simple V-shaped part or rounded part as shown in Figure 3.

The means for operating the flame holder 20 between its two above described positions is preferably a manually controlled power mechanism such as an electric motor, hydraulic motor, cable system, or a cylinder and piston motor. In Figure 5 I have shown a cylinder and piston unit 30 having an extending piston rod 31 for actuating or moving the flame holder. The piston rod 31 is operatively connected with a lever 32 which in turn is connected with one of the flame holder shafts 24. I prefer to interpose a frictional connection between the lever 32 and the shaft 24 so that the flame holder may be moved by an overriding manual control in the event the cylinder and piston unit 30 or other elements of the regular operating system fail or become inoperative. Accordingly, in Figure 6 I have shown a simple friction connection in which the shaft 24 passes through openings in the lever 32 and a plate of friction material 33 having one face engaged against the lever. A cap or washer 34 engages the other side of the friction plate 33 and a collar or nut 35 on the shaft 24 urges the washer 34 against The frictional engagement of the plate 33 with the lever 32 and washer 34 is such that movement of the lever 32 is dependably transmitted to the flame holder 20 during normal operations. However, this frictional engagement may be overcome by the manual overriding operating means so that the flame holder 20 may be moved without movementof the lever 32 or piston rod 31.

The system for operating the cylinder and piston unit 30 includes a pipe 36 carrying actuating fluid pressure and a return pipe 37 for the actuating fluid. A suitable 4-way valve 38 controls the communication of these

pipes

36 and 37 with the pipes 39 leading to the opposite ends of the cylinder and piston unit. The valve 38 is in turn operated by a manual lever 40. The lever 40 may be conveniently positioned in the pilots compartment for ready manipulation and may be, operatively connected with the valve 38 by a link 41 and a lever 42. It will be apparent how the manual lever 40 may be operated to reverse the valve 38 and thus cause actuation of the cylinder and piston unit 30 and movement of the flame holder 20.

The above referred to manual override for operating the flame holder 20 may comprise a lever 43 keyed or otherwise fixed to a shaft 24 of the flame holder 20 and a rod system 44 connected to the lever. The rod system 44 may extend to the pilots compartment so that the flame holder 20 may be manually operated or positioned at any time at the will of the pilot or operator irrespective of the condition of the other operating means.

It is preferred to coordinate the afterburner fuel system and fuel igniting system with the flame holder control so that the several elements of the afterburner apparatus may be simultaneously operated or controlled. The above mentioned electrical lead 19 of the fuel igniting plug 18 extends to a switch 45 and a similar lead 46 continues from the switch to a source 47 of electrical energy. The switch 45' is of the timed type well known to those skilled in the electrical arts so that following actuation it closes the circuit through the

conductors

19 and 46 for a given period of time, say several seconds, and then opens the circuit. The switch 45 is positioned to be operated by a cam projection 47 on the link 41 when the lever 40 is moved in the direction to cause actuation of the flame holder to the operative position of Figure 2. Upon return movement of the link 41 when the flame holder 20 is restored to its idle position the actuation of the switch lever 48 does not affect the switch. A manually operable override is provided for the circuit of the fuel ignitor 18 whereby the pilot or operator may cause ignition of the afterburner fuel at any time. This override control includes a lead 50 connected with the above described lead 19 at a point between the plug 18 and the switch 45. The lead 50 extends to the electrical power source 47 and thus by-passes the timed switch 45. A conveniently positioned manually operable switch 51 is interposed in the lead 50.

The control for the afterburner fuel supply system comprises a suitable throttle valve or control valve 52 connected in the above described fuel supply line 15. The operating lever 53 of the valve 52 is connected with the above described link 41 so that the valve 52 is under the control of the manual lever 40. The valve 52 is operable to admit fuel to the injectors 16 when the lever 40 is moved in a direction to cause actuation of the flame holder 20 to its operative position and the valve is closed to cut off the delivery of fuel to the injectors when the lever 46 is moved in the direction to restore the flame to 6 inclusive, it will be assumed that the turbo jet engine is already in operation so that a stream of turbine exhaust gases is flowing through the afterburner 13 for discharge from the nozzle 14. During normal operations the flame holder 20 is in the idle position illustrated in Figure 4 where it offers a minimum of interference 2.

to the flow of gases through the afterburner and, accordingly, does not appreciably reduce the thrust efiiciency of the powerplant. When additional thrust is required, for example during take-off or combat maneuvering, the manual lever 40 is moved to open the valve 52 and to operate the switch 45. This results in theadmission of fuel into the afterburner through the injectors 16 and the ignition of the fuel by the ignitor 18. Movement of the lever 40 also reverses the valve 38 so that the cylinder and piston unit operates to swing the flame holder 20 through approximately 90 degrees to the active position of Figure 2. In this position the grid 22-23 creates a distributed turbulence in the gas and fuel stream to assure an eflicient burning of the afterburner fuel and also creates a zone of increased velocity which prevents the afterburner flame front from moving upstream toward the injectors 16. It will be seen that a single operation of the manual lever simultaneously supplies fuel to the afterburner, energizes the fuel ignitor 18 for a given period, and moves the flame holder 28 to c the operative position.

When the thrust augmentation is no longer required, the lever 40 is moved in the direction to close the valve 52 and to reverse the valve 38. Thisterminates the delivery of fuel to the afterburner and causes actuation of 3 sure ignition of the afterburner fuel.

the cylinder and piston unit 30. The unit 30 moves the flame holder 20 through approximately 90 degrees to the inactive position of Figure 4 where it again oifers a minimum of resistance to flow of the gases through the tube 13.

In the event the ignitor 18 fails to initially ignite the afterburner fuel, the switch 51 may be manually closed to again energize the ignitor. As a matter of fact, the switch 51 may be manually operated at any time to as- Also, in the event the flame holder operating system fails or becomes inoperative for any reason, the pilot or operator may actuate the rod system 44 to turn the flame holder to any desired position. Furthermore, the rod system control 4344 may be operated at any time to move the flame holder as desired.

In Figures 7, 8 and 8A I have illustrated another form of flame holder and a means for operating the same. In this construction the flame holder comprises two sections or

wings

55 and 56, each having a peripheral ring 57 of about 180 extent. The

grid members

22 and 23, or the equivalent, are carried by the two

wings

55 and 56. The ring 57 of the wing 55 is secured on a sleeve or tubular shaft 58 which passes diametrically through the afterburner tube 13 and has its end supported in suitable bearings 60. The ring 57 of the section or wing 56 has arms 61 which pass through slots 62 in the wall of the tubular shaft 58. This is best illustrated in Figure 8A. The arms 61 are welded or otherwise fixed to an inner shaft 63 which passes through the outer shaft 58. The inner shaft 63 extends beyond the ends of the shaft 58 and its projecting end portions are carried by suitable bearings 64. The construction just described is such that the

wings

55 and 56 may be moved from the idle positions shown in broken lines in Figure 7 to the operative positions shown in full lines where they are in a plane transverse of the tube 13. A streamlined fairing 65 is secured in the tube 13 directly in front of the shaft assembly 58-63 to reduce the interference to the gas flow.

The means for operating the

wings

55 and 56 between their idle and active positions may take various forms. In the particular case illustrated this means comprises a reversible electric motor 66 driving a beveled gear 67. The projecting ends of the

shafts

58 and 63 have opposed beveled pinions 68 meshing with the drive gear 67. The relationship of the gears is such that the

wings

55 and 56 are simultaneously swung from the idle positions to the active positions when the motor 66 is energized to rotate its gear 67 in one direction. When the motor 66 drives the gear 67 in the other direction the

wings

55 and 56 are moved back to the idle positions. The motor 66 may be controlled by a conveniently located reversing switch, not shown, timed to produce the desired movements of the

wings

55 and 56.

Figures 9, 10 and 11 illustrate still another form of flame holder of the invention. In this construction the flame holder 70 is capable of movement between an idle position Where it is entirely outside of or removed from the normal path of the turbine exhaust gases and an active position where it extends across the interior of the afterburner tube 71. The afterburner tube 71 has a dome or recess 72 in its wall for receiving the flame holder 70 when the latter is in the retracted position. The recess '72 may be quite shallow and has a cylindrically curved main wall that is substantially concentric with the wall of the tube 71.

The flame holder 70 has the shape of a substantially round section or segment of a tube presenting cylindrically curved forward and rearward sides and having a marginal ring 73. The ring 73 is smaller in diameter than the afterburner tube 71 to leave suitable clearance between the flame holder and the wall of the tube. The flame holder 70 further includes a grid 74 similar to the above described grid 22-23 except thatits members are curved to conform generally with the wall of the recess 72 as illustrated in Figure 10. The flame holder 70 is supported so that it may be swung between the broken line and full line positions of Figures 9 and 10. The means for supporting the flame holder may take the form of a hinge connection comprising a lug 75 on the tube 71 that is slotted to receive spaced cars 76 on the ring 73. A hinge pin 77 passes through openings in the lug 75 and cars 76 to complete the hinge connection. The hinge connection is preferably in the rear portion of the recess 72. It is preferred to fix the hinge pin 77 to the ears 76 of the flame holder and the pin extends outwardly from the tube 71 or the wall of the recess 72. A lever 78 is secured to the hinge pin 77 and may be connected with the above described piston rod 31 so that the flame holder 70 is adapted to be operated by the control system of Figure 5.

It will be observed that the flame holder 70 of Figures 9, 10 and 11 is completely removed from the path of the turbine exhaust gases when in the idle position within the recess 72, and therefore oflers no, or practically no, resistance to the gas flow during normal powerplant oper ation. When swung to its operative position the flame holder 70 operates in the same manner as the flame holder 20 to provide an eflicient burning of the afterburner fuel and to hold the flame against upstream advancement.

Having described only typical preferred forms of the invention, I do not wish to be limited to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art and fall within the scope of the following claims.

I claim:

1. In apparatus for use with a turbo jet engine having a passage for discharging turbine exhaust gases, the combination of .a tube communicating with said passage to receive the gases therefrom, means for introducing fuel into the tube, a flame holder means in downstream relation to the fuel introducing means, and means supporting said flame holder means for movement between a position within the tube where said flame holder means oifers negligible resistance to the flow of gases through said tube and a flame holding position within the tube where said flame holder means increases turbulence and accelerates the gas stream flowing through said tube.

2.. In apparatus for use with a turbo jet engine having a passage for discharging turbine exhaust gases, the combination of a tube communicating with said passage to receive the gases therefrom, means for introducing fuel into the tube, a flame holding grid means arranged downstream of the fuel introducing means where said grid means increases turbulence and accelerates the gas stream flowing through said tube, means carrying said grid means for movement between an idle position within the confines .of the tube and an active position where said grid means extends transversely across the interior .of the tube, and means for moving the grid between said two positions.

3. In apparatus for use with a turbo jet engine having apassage for discharging turbine exhaust gases, the combination of a tube communicating with said passage to reccive the gases therefrom, means for introducing fuel into the tube, a flame holding grid means spaced in down stream relation to the fuel introducing means, means for moving said grid means between an idle position within the confines of the tube where said grid means offers negligible resistance to the gas flow through the tube and an operative position within the tube where said grid means serves to increase turbulence and accelerate the gas stream in the tube, and a control for the two said means operable to control the delivery of fuel to the first named means and to actuate said means for moving said grid means.

4. In apparatus for use with a turbo jet powerplant having a turbine exhaust tube and means for injecting fuel into the exhaust tube, the combination of a flame holding grid means, means in downstream relation to the fuel inj c ean supnur ine s id gr d means for movement between an idle POSiti n within the confines of the tube and an active position where said grid means extends across the interior of the tube, said grid means being located downstream of said fuel injecting means where said grid means creates turbulence and accelerates the gas stream flowing through said tube, and remotely controlled means for moving the grid between said positions.

5. In apparatus for use with a turbo jet powerplant having a turbine exhaust tube and means for injecting fuel into the exhaust tube, the combination of a flame holding grid means, means in downstream relation to the fuel injecting means pivotally supporting said grid means for movement between an inactive position within the tube and an active position where said grid means extends across the tube to inCrease the turbulence and velocity of the gas stream, and remotely controlled power means for pivoting said grid means between said positions.

6. In apparatus for use with a turbo jet powerplant having a turbine exhaust tube and means for injecting fuel into the exhaust tube, the combination of a flame holding grid means, pivotal support means for mounting said grid means in the tube for swinging movement between an active position within the tube where said grid means extends substantially transversely across the interior of the tube in which position said grid means serves to increase turbulence and accelerates the gas stream in the tube, and an idle position within the tube where said grid means lies in a plane substantially parallel with the long axis of the tube, and means for swinging said grid means between said positions.

7. In apparatus for use with a turbo jet powerplant having a turbine exhaust tube and means for injecting fuel into the exhaust tube, the combination of a flame holding grid in the tube, means for supporting the grid for movement about an axis substantially perpendicular to the long axis of the tube so as to be movable between an idle position where it has an edge in the stream facing upstream and an active position where it extends transversely across the interior of the tube, and means for moving the grid about said axis.

8. In apparatus for use with a turbo jet powerplant having a turbine exhaust tube and means for injecting fuel into the exhaust tube, the combination of a flame holding grid in the tube, means for supporting the grid for movement about an axis substantially perpendicular to the long axis of the tube so as to be movable between an idle position where it has an edge facing upstream and an active position where it extends transversely of the tube, a streamlined fairing on said edge for reducing the resistance to gas flow when the grid is in the idle position, and means for moving the grid about said axis.

9. In apparatus for use with a turbo jet powerplant having a turbine exhaust tube and means for injecting fuel into the exhaust tube, the combination of a flame holding grid comprising two wing sections, means for mounting the sections in the tube for movement about an axis diametric of the tube, and means for moving the sections between positions where they extend axially of the tube and positions where they extend transversely of the tube.

10. In apparatus for use with a turbo jet powerplant having a turbine exhaust tube and means for injecting fuel into the exhaust tube, the combination of a flame holding grid of substantially circular shape when projected along the axis of said tube and of substantially cylindrical curvature, means supporting the grid for movement between a retracted position where it lies adjacent the wall of the tube to substantially conform thereto and an active position where it extends across the interior of the tube, and means for moving the grid between said positions.

11. In apparatus for use with a turbo jet powerplant having a turbine exhaust tube and means for injecting fuel into the exhaust tube, the combination of a flame holding grid of substantially circular shape when projected along the axis of said tube and of substantially cylindrical curvature, means supporting the grid for movement between a retracted position where it lies adjacent the wall of the tube to substantially conform thereto and an active position where it extends across the interior of the tube, the wall of the tube having a recess for receiving the grid when in said retracted position, and means for moving the grid between said positions.

12. In apparatus for use with a turbo jet engine having a passage for discharging turbine exhaust gases,

the combination of a tube communicating with said passage to receive the gases therefrom, means for introducing fuel into the tube, a flame holder in downstream relation .to the fuel introducing means, means supporting the flame holder in downstream relation to the fuel introducing means for movement between an inactive position within the tube and an active position within the tube where it extends across the interior of the tube, remotely controlled power actuated means for moving the flame holder, and a manually operable overriding control for moving the flame holder.

13, In apparatus for use with a turbo jet engine having a passage for discharging turbine exhaust gases, the combination of a tube communicating with said passage to receive the gases therefrom, means for introducing fuel into the tube, a flame holder means in down stream relation to the fuel introducing means, an ignitor means for igniting said fuel in the tube, means supporting said flame holder means for movement between an inactive position and a position where said flame holder means extends across the tube and increases turbulence and accelerates the gas stream, and an operating system operable to supply fuel to the fuel introducing means, energize the ignitor and move the flame holder.

14. In apparatus for use with a turbo jet engine having a passage for discharging turbine exhaust gases, the combination of a tube communicating with said passage to receive the gases therefrom, means for introducing fuel into the tube, a flame holder means in downstream relation to the fuel introducing means, an

ignitor means for igniting said fuel in the tube, means supporting said flame holder means for movement between an inactive position and a position where said flame holder means extends across the tube and increases turbulence and accelerates the gas stream, and an operating system operable to supply fuel to the fuel in troducing means, energize said ignitor and move said flame holder means, said system including a manually operable control part for initiating operation of the systom.

15. In apparatus for use with a turbo jet engine having a passage for discharging turbine exhaust gases, the combination of a tube communicating with said passage to receive the gases therefrom, means for introducing fuel into the tube, a flame holder in downstream relation to the fuel introducing means, an ignitor for igniting said fuel in the tube, means supporting the flame holder for movement between an inactive position and a position where it extends across the tube to create increased turbulence and acceleration of the gas stream, and an operating system operable to supply fuel to the fuel introducing means, energize the ignitor and move the flame holder, said system including a valve governing the delivery of fuel to the fuel introducing means, a fluid pressure actuated unit for moving the flame holder, and a switch for controlling the ignitor.

16. In apparatus for use with a turbo jet engine having a passage for discharging turbine exhaust gases, the combination of a tube communicating with said passage to receive the gases therefrom, means for introducing fuel lift into the tube, a flame holder in downstream relation to the fuel introducing means, an ignitor for igniting said fuel in the tube, means supporting the flame holder for movement between an inactive position and a position where it extends across the tube to create increased turbulence and acceleration of the gas stream, and an operating system operable to supply fuel to the fuel introducing means, energize the ignitor and move the flame holder, said system including a fuel supply valve controlling the delivery of fuel to the fuel igniting means, a fluid pressure actuated unit for moving the flame holder, a valve controlling said unit, a circuit for energizing the ignitor, a switch in said circuit, and a single manually operable member for operating said valves and said switch.

17. In apparatus for use with a turbo jet engine having a passage for discharging turbine exhaust gases, the combination of a tube communicating with said passage to receive the gases therefrom, means for introducing fuel into the tube, a flame holder in downstream relation to the fuel introducing means, the flame holder including a ring adapted to move in the tube with clearance, and grid members in the ring, and means supporting the flame holder for movement between a position within the confines of the tube where it oflers negligible resistance to the flow of gases through the tube and a flame holding position within the tube where it creates increased turbulence and acceleration of the gas stream flowing through the tube.

18. In apparatus for use with a turbo jet engine having a passage for discharging turbine exhaust gases, the combination of a tube communicating with said passage to receive the gases therefrom, means for introducing fuel into the tube, a flame holder in downstream relation to the fuel introducing means, the flame holder including a ring adapted to move in the tube with clearance, and grid members of V shaped cross section in the ring, and means supporting the flame holder for movement between a position in the tube where it offers negligible resistance to the flow of gases through the tube and a flame holding position in the tube where it creates increased turbulence and acceleration of the gas stream flowing through the tube.

19. In a power plant, structure defining a combustion chamber for flow of gases therethrough at velocities in excess of 50 feet per second, a flame-holder means to increase turbulence and accelerate the flow of gases through said chamber and for effecting a degree of stagnancy in the stream of gases flowing through/the chamber suflicient for maintenance of a flame formation, and means pivotally mounting said flame-holder for pivotal movement between an operative position where it extends generally transversely of the gas stream and an inoperative position where it extends generally parallel to said gas stream.

20. In a gas turbine power plant comprising a compressor for gases supplied to the plant, heating means for gases compressed by said compressor, a turbine for ex tracting from the heated gases at least suflicient energy to drive the compressor, an exhaust nozzle for the gases discharged from the turbine, and structure defining a combustion chamber through which gases flow in passing from the turbine to the exhaust nozzle; means for supplying fuel to the gas stream at a point therein downstream of the gas heating means for burning in said combustion chamber, a flame holder means mounted in the combustion chamber in spaced downstream relation to said fuelsuppiying means for movement between an operative position where said flame holder means increases turbulence and accelerates the flow of gases through said chamber and creates a sufficient degree of stagnanoy to cause retention of a flame formation in the combustion chamber resulting from burning of fuel from said fuel-supplying means and an inoperative position where the pressure drop produced thereby in the gas stream therepast is degree of stagnancy in the stream of gases that a flame i formation may be maintained, and means mounting said flame holding means for movement between a first position where it produces a pressure drop in the gas stream in spaced downstream relation to said fuel-admitting means and a second position where said pressure drop is materially reduced.

22. In a power plant, structure defining a combustion chamber adapted for flow of gases therethrough at velocities in excess of 50 feet per second, flame holding means within the chamber to increase turbulence and accelerate the flow of gases through said chamberand for effecting a degree of stagnancy in the stream of gases flowing through the chamber sufficient for maintenance of a flame formation, and means supporting said flame holding means for movement between a first operative position where the flame holding means extends generally transversely of the gas stream and a second inoperative position where the flame holding means extends generally parallel to the gas stream.

23. In a gas turbine power plant having means for compressing gases supplied to the plant, means for heating the compressed gases and a turbine for extracting at least suflicient energy from the compressed heated gases to drive said compressing means; the combination of casing structure receiving the gases exhausting from the turbine, defining a combustion chamber downstream from the turbine and terminating in an exhaust nozzle; a flame holder in said combustion chamber; said flame holder being constructed in two halves separately mounted on an axis for pivotal movement between first positions where they extend generally transversely of the combustion chamber and second positions where they extend generally longitudinally of the combustion chamber and downstream of their pivotal mountings, and mechanism for moving the two halves of the flame holder simultaneously between said first and second positions.

References Cited in the file of this patent UNITED STATES PATENTS 424,305 Jones Mar. 25, 1890 2,394,384 Horstrnann Feb. 5, 1946 2,409,176 Allen Oct. 15, 1946 2,421,518 Molloy June 3, 1947 2,566,373 Redding Sept. 4, 1951 FOREIGN PATENTS 922,032 France Jan. 20, 1947 298,145 Germany June 1, 1917