US2577918A - Air jacketed combustion chamber flame tube - Google Patents

Description

Dec. 11, 1951 H. E. RowE AIR JACKETED COMBUSTION CHAMBER FLAME TUBE Filed May 8, 1946 INVENToR. AMM M Dec. l1, 1951 EH. E. RowE Filed May 8, 1946 AIR JACKETED COMBUSTION CHAMBER FLAME TUBE 2 SHEETS-SHEET 2 Fig, 4

INVENTOR. g, @dau- Patented Dec. 11, 1951 AIR JACKETED COMBUSTION CHAMBER FLAME TUBE Harold E. Rowe, New York, N. Y., asslgnor to The M. W. Kellogg Company, New York, N. Y., a

corporation of Delaware Application May 8, 1946, Serial No. 668,181

(Cl. 6ft-39.65)

13 Claims.

The present invention relates to combustion units of the general character in which fuel is injected into a chamber or furnace and burned in the presence of air, and although it has a wide range of utility, it is particularly useful, as for example, in connection with gas turbine plants.

One object of the present invention is to provide new and improved combustion units of the general character referred to.

Another object of the present invention is to provide new and improved combustion units of the general character referred to, which permit the attainment of highjcombustion rates with comparatively low pressure drops. A combustion unit of this improved type, constructed in accordance with the present invention, is especially advantageous in a gas turbine system as it occupies a minimum of space, permits compact layouts in connection with other units of the system, and involves a minimum of thermodynamic losses.

A further object of the present invention is to provide a new and improved combustion unit of the general type referred to, in which the combustion air inlet and the exhaust outlet are designed and located to permit the compact arrangement of said combustion unit in line with other units of a plant, while aiording high combustion rates and low pressure drops. A combustion unit of this improved type is particularly useful in connectionwith certain proposed aircraft practices in which the principal elements of a gas turbine plant, as for example, the compressor, combustion unit and gas turbine, are arranged in line.

Another object of the present invention is to provide a new and improved ignition or primary combustion unit by which primary ignition is effected in a rapid, thorough, intimate manner in accordance with a substantially predetermined iiow pattern, and from which the ignited mixture, rich with unburnt fuel, is projected into the secondary combustion chamber as a stream having substantially predetermined shape, course and other flow characteristics.

In accordance with certain features of the present invention, primary combustion is carried out within two confined separate spaces, and the ignited products rich with unburnt fuel elements are projected from these spaces into a secondary combustion chamber as two separate substantially parallel streams. In the secondary combustion chamber, air is vortically coursed according to a predetermined flow path around each stream as an axis while the stream and the air advance towards the exhaust end of said chamber. The unburnt fuel elements projected along the axes of the two vortices, intimately,

thoroughly and rapidly mix with the air whirling around them to form an iniiammable mixture which, by its burning always maintains the temperature above the extinction temperature until combustion of the unburnt fuel elements is substantially complete.

The air admitted into the secondary combustion chamber-may be directed in the vortical form described, in any one of a number of ways in accordance with the present invention. In one form of the invention, there are provided two annular air registers around the primary combustion or ignition chambers respectively, vaned to cause theA air admitted therethrough to be directed in the form of two vortical streams having opposite senses of rotation. Since these air registers desirably extend concentrically around the axes of the ignition chambers, the vortical air streams, as they are projected from the air registers, wind themselves around the core streams of the fuel-rich mixture projected from the ignition chambers.

In another alternative arrangement, an air register at the head end of the secondary combustion chamber near one wall thereof is adapted to admit the air into said secondary combustion chamber and direct it substantially in its axial plane towards the opposite wall of said chamber where it is divided by the chamber wall into two streams having vortical, oppositely whirling characteristics.

In a further alternative form, an air register at the head end of the secondary combustion chamber is adapted to admit the air into said secondary combustion chamber, and direct and divide it into two streams flowing in opposite directions from its axial plane, and towards the chamber walls where they are deflected for vortical flow around the core streams projected from the ignition chambers.

As far as certain aspects of the invention are concerned, these alternative forms of air register may be employed separately without the annular air registers described, or may be employed in coniunction therewith.

The ilow of combustion air through the unit is in the general direction of alignment of the primary and secondary combustion sections, and the primary combustion chamber walls over which the combustion air flows towards the secondary combustion chamber are aerodynamically designed to afford streamline flow of the air thereover.

It has been found that a combustion unit constructed in accordance with the present inven tion has an extremely high energy release rate. For example, energy release rates of 4,000,000 B. t. u. per cubic foot per hour at atmospheric pressure, and 20,000,000 B. t. u. per cubic foot per hour at 90 p. s.-i has been obtained. lFurthermore, these high lenergy release rates have been effectively attained withoutundue complications in the structure of the unit, and with a minimum of destructive action thereon.

Various other objects, features and advantages of the invention will be apparent from the following particular description, and from an inspection of the accompanying drawings, in which- Fig. 1 is a vertical longitudinal section of a combustion unit embodying the present invention:

Fig. 2 is a transverse section taken on line 2-2 oi' Fig. 1;

Fig. 3 is a transverse section taken on line 3-3 of Fig. 1;

Fig. 4 is a detail vertical section of the combined primary combustion chamber and annular air register unit;

Fig. 5 is an end view of the combined primary combustion chamber and annular air register unit shown in Fig. 4;

Fig. 6 is a fragmentary perspective of the combined primary combustion chamber and annular air register unit shown in Fig. 4; and

Fig. 'l is a section of one of the air registers taken on line 1--1 of Fig. 3 but on a larger scale.

Referring to the drawings, the combustion unit is shown of the type which is particularly adaptable for use in connection with gas turbine plants. However, it must be understood that as far as certain aspects of the invention are concerned, the unit of the present invention may be adapted for other combustion uses where high energy release rates are required.

'I'he combustion unit of the present invention comprises an air inlet duct section I0 at one end, a secondary combustion section II at the other end, and an intermediate ignition or primary combustion section I2 between the two end sections III and II. The unit sections I0, II and I2 are connected end to end in axial alignment in a manner to be made apparent.

The air inlet duct section I0 comprises an air duct 8 coaxially mounted with respect to the primary combustion section I2, and provided at its inlet end with a ange 9 for bolting connection to the outlet of an air compressor. Air duct 8 is shown of the type especially useful in connection with modern axial flow air compressors, which discharge compressed air with relatively large velocity head. The duct 8 is therefore shown with its cross-sectional area increasing progressively in the direction of flow in the form of a diffuser to recover a large part of this velocity head and convert it into pressure head suitable for the conditions desired in the combustion chambers. If the velocity head of the air at the inlet of the secondary combustion chamber to be described is too great, then the pressure drop through said chamber may also be comparatively large. Such large pressure drops are undesirable especially because of their adverse effect on the overall eillciency of the system of which the combustion unit is a part. The air admitted into the secondary combustion chamber must, however, have the necessary velocity to produce the high combustion rate required, since there is a relationship between the combustion rate that 4 can be obtained and the velocity of the air entering said combustion chamber.

The shape of the air duct 8 is shown of a specific design for application to a gas turbine layout proposed in connection, for example. with an aircraft installation. In such a power plant. all of the principal elements of the plant, as for example, the air compressor, the combustion unit and the gas turbine, would be arranged in line. In the particular layout shown in the drawings, the compressor is disposed in front of the combustion unit with its discharge end connected to the air duct inlet, while the gas turbine is disposed at the exhaust end of the combustion unit. Generally, a number of these combustion units are circularly arranged around the axis of the turbine wheel.

'Ihe primary combustion section I2 comprises an outer housing wall Il which is shown in the form ot a metal shell of progressively increasing cross-section downstream. and which is connected with the outlet of the air duct B. The housing shell I3 is provided with a flange I6 at its inlet end for bolt connection to a corresponding flange I1 on the outlet end of the air duct 8, and is connected at its outlet end to the outer housing wall 45 of the secondary combustion section I I, desirably by welding.

Supported in the interior of the housing shell I3 in a manner to be made apparent are two furnace wall structures 25, shown in the form of metal shells disposed alongside of each other on opposite sides of the longitudinal center line of the unit, and respectively defining therein separate primary combustion or ignition chambers 24. Each furnace wall structure 25 comprises a nose or head 26 at its inlet end of substantially hemispherical or other suitable design affording streamline flow of the air thereover as it proceeds towards the secondary combustion section II and a conical nozzle 21 at its discharge end extending towards the secondary combustion chamber to be described. Each furnace wall structure 25 has coaxially connected, desirably by welding to its inlet end, a cylindrical tubular shield 28 for the fuel injection nozzle 3| to be described.

The fuel is admitted under pressure through a feed line 30 passing through a wall of the air duct 8, and having at its discharge end the spray nozzle 3I which projects through the tubular shield 2l and opens into the interior of the primary combustion chamber 2l. This spray nozzle JI is shown of the mechanical type adapted to project and whirl liquid fuel under pressure into the interior of the primary combustion chamber 24 in the form of a hollow cone, and to atomize said fuel in said chamber.

Combustion air is diverted into the interior of each of the primary combustion chambers 2l to form an inflammable mixture with the fuel injected therein. T0 admit air into the interior of each of the primary combustion chambers 2l, and to direct the air along a predetermined course with respect to the injected fuel, head end 26 has coaxially mounted therein a flaring or conical baille 35, the smaller end of which is connected to the tubular shield 28. A series of air inlet holes 36, distributed around the axis of the chamber 2l,

are provided in head end 26 for directing primary air along the wall of head end 26 towards the inlet of the chamber nozzle 21. At the outlet larger end of head end 26, there is provided an air deflector 31, shown in the form of a ange extending generally radially inwardly from said wall near the inlet end of the chamber nozzle 21, and curved along one face 38 to direct the air which impinges on it towards the inside of the conical baffle 35, and along the wall'thereof. The air for primary combustion when it reaches the proximity of the atomized fuel, forms a vortex ring around the injected fuel cone. Suilicient fuel from the fuel cone is drawn and diffused to the annular axis of the air vortex ring to form at said axis an inflammable mixture.

To ignite the inflammable mixture formed at the core of the air vortex ring described, there is provided for each Aof the primary combustion chambersv 24 a spark plug 40 which extends through the housing wall I3, and through the Wall of chamber nozzle 21, so that its sparking end is near the outlet of the conical baille 35. The lnflammable mixture along the vortex ring core after initial ignition remains lit continuously to afford a pilot light along said axis. The spark plug 40 is preferably made to operate only long enough to initiate the ignition, although it can be made to operate continuously if desired.

Fuel injection nozzle 3|, as already indicated, directs a metered quantity of fuel into a, fixed pattern of flow in a protected space whose volume is adjusted according lto the maximum capacity of fuel to be consumed. The recirculating flow pattern which is maintained in the ignition space returns heat and so-called active centers from the stable llame into the air-borne cloud of fluid drops in the chamber 24. thus maintaining contlnuous ignition.

The ignited fuel-rich mixture is projected at high speed substantially in the form of a cylindrical stream from the nozzle end 21 of each chamber 24 into the secondary combustion chamber I I.

The secondary combustion section I I comprises an outer housing wall 45 in the form of a metal shell having a cylindrical body section 4I connected at its inlet end to the primary combustion housing shell I3, in the manner described, and connected at its outlet end by a flange bolt connection 42 to an exhaust end section 43 progressively decreasing in diameter downstream. The neck of housing section 43 has a flange 44 for stud or bolt connection to a conduit member 46 of the gas turbine or other unit of the plant or system.

In the interior of the outer housing shell 45 is a secondary wall structure41 shown in the form of a metal shell coaxially mounted with respect to the outer shell 45 and peripherally spaced therefrom, to define therewith an annular air flow passage 48 having its inlet end 52 open and communicating with the space in the housing I3. Inner shell 41 defines a secondary combustion chamber 50, and is supported with respect to the outer housing wall 45, as for example, by means of spacers 5I welded or otherwise fastened in position to the inner shell 41 and engaging the outer housing wall. The outer housing wall 45, since it is not subjected to high temperatures in operation, may be made of any preferred material. Inner shell 41 should be made of a material capable of withstanding high temperatures; this material need not be of high strength as the pressures on the faces of inner shell 41 are balanced.

The inner shell 41 has a cylindrical body section 49 and an exhaust end section 49a progressively decreasing downstream and terminating in a throat snugly embra'ced by the neck of the housing shell section 43. The snug engagement between the two sections 43 and 49a serves in conjunction with the spacers 5I to center and removably support the inner shell 41 -in the outer housing wall 45. The downstream converging character of the exhaust end section 49a of the inner shell 41 serves to discharge the exit gases at the desired velocity.

In order to direct air into the interior of the secondary combustion chamber 56, and vortically around the ignited streams of fuel-rich mixture discharged from the ignition chambers 24, there are provided two air register devices 60 disposed around the outlet ends of the lprimary combustion chambers 24 respectively. The inlet end of the combustion chamber 50 is closed by a circular plate 6I secured to the front end of the shell 41, as for example, by welding. Plate 6I has two circular openings 62 on opposite sides of its center.

line for concentrically receiving the respective nozzles 21 of the furnace wall structures. Each of these plate openings 62 is larger than the section of the corresponding nozzle 21 opposite said opening to dene with said nozzle an annular air admission port 63, divided by a series of vanes 64 equally spaced and secured. as for example, by

Welding at their inner peripheries to said nozzle,

land at their outer peripheries to a cylindrical shroud ring 65. The shroud ring 65 is substantially of the same diameter as the corresponding plate opening 62, is mounted in axial registry therewith, extends toward the exhaustv end of the unit from the register plate 6I, and is made fast to said plate, as for example, by welding. Shroud ring 65 is of such Width as lto be substantially flush at its outlet end with the outlet end of nozzle 21.

The Vanes 64 of each air register 60 are substantially equal in length to their corresponding shroud ring 65, and are curved to direct the air in a tangential direction to impart to it as it enters the secondary combustion chamber 50 a whirling vortical movement around the axis of the register. The vanes 64 in the two air registers 60 extend in opposite directions, so that the two air vortices created thereby have opposite senses of rotation. In the form illustrated, the two vortical directions are such as to cause the outer layers of the two vortices in the vertical axial plane of the secondary combustion chamber 56 to travel downwardly.

Since the ignited, fuel-rich exhaust mixture from each primary combustion chamber 24 is projected into the primary combustion chamber 50 as a straight stream along its corresponding register axis, the air admitted into this chamber through the corresponding register 60 vortically circulates around its projected stream as it advances towards the discharge end of said chamber. As these axial columns rich with unburnt fuel elements advance along the secondary combustion chamber 50, the unburnt fuel element content thereof is rapidly, intimately and thoroughly mixed with the encompassing cyclonic air to form an inflammable mixture which, as it continuously burns, maintains the temperature above the extinction temperature until combustion of the unburnt fuel elements is substantially complete. Substantially complete combustion inthe chamber 50 is thereby assured, even in the presence of large quant-ities of excess air.

Extinction temperature may be deilned as that temperature below which the combustion velocity falls to a negligible level and depends on the instantaneous air-fuel ratio, the magnitude of heat losses, the constituents of the atmosphere produced by previous stages oi' the combustion process, etc.

Some of the air supplied to the chamber Il is admitted through supplementary air registers 10 and 15 to predetermine more definitely the vortical course of the two air streams projected from the primary combustion chambers 24. Register 10 is shown mounted near the upper section of the combustion unit, and comprises an opening or port 1i in the plate 6I. shown in the form of a rectangular oblong, disposed with its longitudinal axis substantially in the vertical axial plane of the secondary combustion chamber 50. Superposed vertically spaced deector vanes 12 extend from this register port 1I towards the exhaust end of the secondary combustion chamber 50, and are held between a pair of parallel side plates 13 welded or otherwise made rigid with said vanes and the register plate il. Vanes 12 are curved to deflect the air downwardly toward the bottom wall of combustion chamber 50 in the vertical axial plane of the combustion chamber 50 so that said bottom wall may divide this air into two vortices which merge with the two air vortices projected from the two annular air registers $0, thereby adding impetus of predetermined coursing character to the vortical air streams.

The other additional register 15 comprises a port 16 in the plate 6I, shown in the form of a rectangular oblong centrally located with respect to the vertical axial plane of the secondary combustion chamber 50, and disposed with its longitudinal axis extending substantially at right angies to said plane. Two sets f deilector vanes 11 and 18 are arranged across the outlet side of the register port 18 between a pair of superposed plates 19 welded or otherwise made rigid with said vanes and the register plate 6|. The sets of vanes 11 and 1l are curved in opposite directions as shown in Fig. 7, so that the air admitted through the register port 16 is divided into two diverging streams in the general direction of rotation of the two air vortices created by the annular air registers 60.

The three sets of registers 60, and 15 serve to form two air vortices having substantially predetermined fiow patterns and substantially cornpletely filling the secondary combustion chamber 50. l

As far as certain aspects of the invention are concerned, the two annular air registers 60, the air register 10, and the air register may each be used alone or any combination of them may be used.

As the air flows in the housing i3 and over the shells of the primary combustion chambers 24, it cools said shells and the walls of said housmg.

The air which is diverted from the air stream flowing `into the secondary combustion chamber 50, into the annular ow passage 4l, cools the inner and outer walls 41 and 45 of the secondary combustion section Il, and at the outlet of said section may be merged with the exhaust from the secondary combustion chamber. For that purpose, the exhaust end section 49a of the inner shell 41 has a series of openings 80 communicating with the air now passage 48.

The combustion unit of' the present invention can be made to effectively afford outlet temperatures ranging from as low as 200 F. to as high as 3,000: F. The embodiment shown is best adapted to provide outlet temperatures ranging from 500 F. to 1,800 F.

The combustion unit of the present invention permits stable operation over a wide range otiuel to air ratio for varying loads without the necessity of adjusting the air now. At the same time. the combustion u'nit avoids the deposition oi soot and coke in the ignition zone. and is capable of operation with large quantities of gases and air over a wide range of load without smoking.

Furthermore, the unit of the present invention produces high rates of combustion, while requiring only a very small pressure drop of air passing through the chamber. The unit, therefore. does not become a drag on the over-al1 eillclency of the plant system.

The unit of the present invention in operation requires a minimum of attention, and the cost of its maintenance is comparatively low. 'Ihe unit in operation is free from direct wall impingement of the flame, so that rapid deterioration of the chamber wall is avoided. The unit therefore has an active life which is comparatively long, especially when its extremely high rate of energy liberation is considered.

The unit of the present invention is especially suitable for use in gas turbine aggregates. It

may also be used, however, for any application4 in which air is to be heated by burning fuel in it. and it combines the advantages of compactness, cleanliness of operation and small power requirements.

As many changes can be made in the abovel apparatus. and many apparently widely different embodiments of this invention can be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not limitative.

What is claimed is:

l. In 'a combustion unit, the combination comprising a hollow body defining a primary combustion chamber and having an open outlet end and an inlet end with passageways therein for entrance of primary combustion air, a second hollow body defining a secondary combustion chamber and having an open outlet end, an inlet end contiguous to the outlet end of said first body and in open communication therewith, and passageways adjacent said inlet end for entrance of secondary combustion air, an air duct having its line of flow extending in substantial alignment with said combustion chambers and adapted to supply primary air and secondary air to said passageways respectively, fuel supply means opening in said primary combustion chamber adapted to supply fuel in proportion to provide a fuel-rich mixture with said primary air, mixture forming means in said primary combustion chamber for mixing said fuel and primary air, means in said primary combustion chamber adapted to ignite the fuel and air mixture for primary combustion, whereby burning fuel-rich products of primary combustion are adapted to issue out of the outlet end of said primary combustion chamber and project into said secondary combustion chamber, and means for coursing at least part of the secondary combustion air from said air duct into said secondary combustion chamber in the form of two adjoining-air vortices circulating in opposite directions around axial zones of projected burning primary combustion products.

2. In a combustion unit, the combination comprising a pair of separate adjoining hollow bodies having open outlet ends and defining primary combustion chambers, a further hollow body deilning a secondary combustion chamber and having an open outlet end, an inlet end contiguous to the outlet ends of said pair of hollow bodies and in open communication therewith, means for supplying fuel and air into each of said bodies for forming a fuel-rich, fuel-air mixture, means for igniting said mixture in each of said bodies to produceprimary combustion thereof and to project the burning fuel-rich products of primary combustion into said secondary combustion chamber as two substantially parallel burning streams extending lengthwise of said secondary combustion chamber. and means for circulating a stream of air vortically around each of said burning streams and along said secondary combustion chamber to form iniiammable mixtures in said secondary combustion chamber for flame propagation therealong.

3. In a combustion unit, the combination comprising a tubular body having a wall at one end and open at its' other end and defining a combustion chamber, said wall having a pair of spaced openings therein, means for projecting a pair of parallel streams of burning fuel-air mixture rich in fuel component through said openings into said combustion chamberand lengthwise thereof, and means for admitting combustion air into said combustion chamber through said end wall and defiecting it vortically into two streams rotating in opposite directions around said burning streams respectively to form in said chamber flame propagating mixtures.

4. In a combustion unit, the combination comprising means dening a .primary combustion section and including a pair of adjoining tubular outlet members disposed with substantially parallel lines of flow, means for supplying fuel and air into said combustion section means to form a fuel-rich, fuel-air mixture, means in said combustion section means for igniting said mixture to produce primary combustion thereof and to project the burning fuel-rich products of primary combustion as a pair of burning streams through said outlet members respectively, means dening a secondary combustion chamber having its inlet end in communication with said outlet members, annular air registers around said outlet members respectively for admitting two streams of combustion air into said secondary combustion chamber, and at the same time deiiecting them vortically in opposite rotational directions around said burning streams respectively, to form ilame propagating mixtures in said secondary combustion chamber, and means for conducting air to said registers.

5. In a combustion unit, the combination comprising a tubular body having a wall at one end and dening a combustion chamber, said wall having openings therein, means for projecting a fuel-rich, burning, fuel-air mixture through said openings into said combustion chamber for ow lengthwise of said combustion chamber, an air register in said end wall near a peripheral portion thereof for admitting air into said chamber, said register including baiiles shaped to deect said admitted air substantially transversely of said chamber across the center thereof and towards a -peripheral portion of said wall opposite said'lrst mentioned peripheral portion, whereby said admitted air is divided by the walls of said tubular body into two vortical streams with opposite senses of direction, said projected mixture being streamed substantially axially through said vortically moving air streams to form ame propagating mixtures in said chamber, and means for conducting air to said register.

6. In a combustion unit, the combination comprising a tubular body having a wall at one end thereof and dening a combustion chamber, said end wall having openings therein, means for projecting a fuel-rich, burning, fuel-air mixture through said openings into said combustion chamber for ow lengthwise of said combustion chamber, an air register in said end wall near a peripheral portion thereof and between said peripheral portion and said openings for admitting air into said combustion chamber, said register including batlies shaped to deect and divide said admitted air into two streams diverging towards opposite portions of the peripheral walls of said tubular body into two oppositely rotating vortical streams,v said projected mixture being streamed substantially axially through said vortical air streams to form flame propagating mixtures in said chamber, and means for conducting air to said register.

7. In a combustion unit, the combination comprising a tubular body having a wall at one end thereof and defining a combustion chamber, said end wall having openings therein, means for projecting a fuel-rich, burning, fuel-air mixture through said openings into said combustion chamber for now lengthwise oi said combustion chamber, means for admitting air into said combustion chamber through said end wall and coursing said air lengthwise along said combustion chamber in the form of two oppositely rotating adjoining vortical streams, an air register in said end wall between said air admitting means and the periphery of said end wall for admitting supplementary air into said chamber, said register including baiiles for deecting said supplementary air substantially transversely of said combustion chamber and between said vortical air streams, whereby said supplementary air is merged with said vortical air streams and aids in coursing said latter streams, said projected mixture being streamed substantially axially through said vortical air streams to form flame propagating mixtures in said chamber, and means for conducting air through said register.

8. In a combustion unit, the combination comprising a tubular body having a wall at one end thereof and dening a combustion chamber, said end wall having openings therein, means for projecting a fuel-rich, burning, fuel-air mixture through said openings into said combustion chamber for i-low lengthwise of said combustion chamber, means for admitting air into said combustion chamber through said end wall and coursing said air lengthwise along said combustion chamber in the form of two oppositely rotating adjoining vorticalstreams, an air register in said end wall near a peripheral portion thereof and between said peripheral portion and said air admitting means for admitting supplementary air into said chamber, said register including baiiles shaped to deect and divide said supplementary air into two streams diverging towards opposite portions of the peripheral walls of said tubular body, whereby said supplementary air is merged with said vortical air streams and aids in coursing said latter streams, and means for conducting air to said air register, said projected mixture being streamed substantially axially through saidvortical air streams to form flame propagating mixtures in said chamber.

9. In a combustion unit, the combination'comprising a tubular body having a wall at one end 11 thereof and defining a combustion chamber, said end wall having a pair of spaced openings therein, means for projecting a fuel-rich, burning, fuel-air mixture through said openings for flow lengthwise of said chamber as two substantially parallel burning streams, annular air registers around said openings for admitting two streams of air into said combustion chamber, said registers including bafiles shaped to deflect said admitted air streams vortically in opposite rotational directions around said burning streams respectively to form flame propagating mixtures in said combustion chamber, means for conducting air to said air registers, and means separate from said air registers for admitting supplementary air into said combustion chamber between said vortical air streams. whereby said supplementary air is merged with said vortical air streams and aids in coursing said latter streams.

10. In a combustion unit, the combination comprising a tubular body having a wall at one end thereof and dening a combustion chamber, said end wall having a pair of spaced openings therein, .means for projecting a fuel-rich, burning, fuel-air mixture through said openings for flow lengthwise of said chamber as two substantially parallel burning streams, annular air registers around said openings for admitting two streams of air into said combustion chamber, said registers including bales shaped to deflect said admitted air streams vortically in opposite rotational directions around said burning streams respectively to form flame propagating mixtures in said combustion chamber, a further air register in said end wall between the periphery thereof 35 combustion chamber having an inlet at one end and an outlet at the other end, a tubular baille in the interior of said chamber Baring from the inlet end of said chamber towards said outlet end and defining with said chamber wall an annular air iiow passage having an outlet communicating with the space in the interior of said tubular baule, said wall having one or more air inlet openings near said inlet end, means for injecting a stream of fuel into the interior of said baille from the inlet end of said chamber towards the outlet end thereof, and means for deilecting air from said flow passage at the outlet thereof in substantially reverse direction towards the inlet end of said chamber, and along the inner periphery of said tubular baille te form an air vortex ring around the injected fuel stream.

12. In a combustion unit, a primary combustion section as described in claim 11, in which the part of said wall encompassing said tubular baiiie is substantially of hemispherical shape, the outlet end of said baille is disposed near and intermediate of the ends of said wall, and the outlet portion of said chamber wall beyond the outlet end of said tubular baille is of cross-section progressively reduced towards the outlet of said chamber.

13. In a combustion unit, a primary combustion section as described in claim 11, in which said defiecting means comprises an annular iiange extending radially inwardly from the periphery of said wall beyond the outlet end of said tubular baiile in the path of flow of the air discharged from said passage, and presenting a deilecting surface to said latter air.

HAROLD E. ROWE.

REFERENCES CITED The following references are of record in the file of this patent:

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