US3038530A

US3038530A - Flame thrower

Info

Publication number: US3038530A
Application number: US786348A
Authority: US
Inventors: Blair B Fowler
Original assignee: Aerojet General Corp
Current assignee: Aerojet Rocketdyne Inc
Priority date: 1959-01-12
Filing date: 1959-01-12
Publication date: 1962-06-12
Anticipated expiration: 1979-06-12

Description

June 12, 1962 B. B. FOWLER FLAME THROWER Filed Jan. 12, 1959 IN V EN TOR. BLAIR B. F OWLE I? ate Ohio

Filed Jan. 12, 1959, Ser. No. 786,348 14 Claims. (Cl. 158-28) The present invention relates to means for igniting a stream of fuel and particularly to the ignition of fuel projected under pressure from a nozzle as a rod-like stream, as in flame throwers.

In a flame thrower it is an important requirement that adequate range be obtained and one consideration to be met is that the fuel stream should leave the nozzle with minimum interference in order that the kinetic energy of the liquid stream he conserved as much as possible while at the same time the stream should ordinarily reach its target aflame so that complete combustion of the fuel shot from the flame thrower results on the restricted target area fired at. Of equal importance is the fact that the range attainable with a fuel stream is doubled or even tripled when properly ignited.

It is an object of the invention to provide ignition means for a flame thrower by which means the nozzle is surrounded by a body of flame whirling about the axis of the jet of fuel so that the surface of the jet is ignited without interference with the main body of the jet.

It is a further object of the invention to utilize the fuel in the flame thrower for ignition of the stream of fuel by providing a fuel bleed directing a small jet of fuel in the form of a spray into a chamber or flame cone surrounding the nozzle and igniting said spray by means serving also to ignite a propellant grain or charge, the burning of which serves to pressurize the fuel in the flame thrower tank, burning of the sprayed fuel after initial ignition being self-supporting.

It is another object of the invention to provide an igniting device having a chamber surrounding the nozzle and an orifice through which the ignited stream of fuel from the flame thrower is ejected, said orifice being surrounded by the intake of a casing surrounding the chamber having orifices connecting the casing to the chamber behind the opening of the nozzle so that the envelope of air entrained by the jet causes a reduced pressure to be set up in the casing resulting in a rush of air at atmospheric pressure to enter said casing and supply the air required to maintain the body of flame surrounding the nozzle after the spray of fuel has been ignited.

With the above and other objects in view, which will appear from the following specification and accompanying illustrative drawings, the invention comprises a fuel nozzle provided with a conduit from which a secondary spray of fuel is projected into a chamber surrounding the nozzle, said chamber having an open end positioned ahead of the nozzle for the passage of'a compact stream of fuel ejected through said nozzle, means to ignite said secondary spray, and a casing surrounding said chamber and having a wall spaced from the wall of said chamber and around the open end of said chamber for the entry of'atmospheric air around the open end of the chamber and into the space between the walls of said chamber and easing, said chamber and casing being in communication behind the forward end of the nozzle whereby air is supplied to maintain the flame of said secondary spray around the nozzle to cause ignition of the surface of said compact stream of fuel issuing from said nozzle.

In the drawings:

FIG. 1 is a fragmentary perspective and sectional view of the nozzle of a flame thrower, the section being taken partly vertical to the'aXial line of the nozzle and partly horizontal to said axis.

FIG. 2 is a detail View in front elevation partly in section of the nozzle of the flame thrower and tank closure on which it is mounted, the nozzle being sectioned on the line 2-2 in FIG. 3.

FIG. 3 is a side elevation of the parts shown in FIG. 2'.

FIG. 4 is a fragmentary perspective View, drawn on a larger scale, of the delivery end of the nozzle, showing parts normally mounted therein withdrawn therefrom.

FIG. 5 is a front view drawn on a larger scale of an air directing member arranged in a chamber surrounding the nozzle.

FIG. 6 is a cross-sectional view of the igniter element.

Referring to FIG. 1, the numeral '10" indicates a portion of the shroud covering the operative parts of the flame thrower. The subject flame thrower is operable on either liquid or thickened (jelled) fuels which are commonly used in flame thrower applications. The fuel under pressure exits the nozzle in similar form with either liquid or jelled fuel, that is, a rod-like stream of fuel. The liquid fuel disperses rapidly after being emitted and ignited from the nozzle into a billowy flame front while the thickened or jelled fuel can be used for long range flame throwing purposes wherein the time for ignition of the jelled fuel is greater in respect to the liquid fuel and the flame front is substantially restrictive. Jelled fuels generally allow a longer maximum range for the flame thrower While liquid fuels can cover a greater area at a much shorter relative range. The problem, of course, is the matter of ignition of a liquid versus a jelled fuel. Partial ignition of any fuel reduces efficiency, therefore, a greater amount of attention is directed to the method of ignition.

A conical flame cone 1]; is mounted Within the shroud 10 and is spaced from the wall thereof by spacing blocks I12 and rivets 13. The flame cone 1 projects for a considerable distance beyond the delivery end of the nozzle.

The flame cone 11 is flattened in the area 13a on its inward side and its open end 14 is spaced peripherally from the edge 15 of an opening in the shroud 10 through which the concentrated stream of fuel, or fuel rod, 16 is ejected.

The nozzle 17 from which the fuel rod is ejected under high pressure is located axially in the flame cone 11, and is carried by a closure 18 screwed into the head casting 19 of the flame thrower to which the pressurized source of fuel 19a is attached. A ball check Valve 1%, attached to the source of fuel 190, may be used to admit pressurized air or the like, the closure '18 closing the delivery end of the tank.

The main fuel passage 20 in the nozzle is stepped down in diameter toward the end of the nozzle ending in length of bore of relatively small diameter.

A passage 21 for a secondary flow offuel is drilled from the inner surface of closure 18 longitudinally through the wall of the nozzle and connects with a transverse passage 22 drilled through the wall of the nozzle adjacent its outer end. The arrangement of the passages is clearly shown in FIGS. 2, 3 and 4. One end of passage 22 is closed by the threaded plug 23 and the opposite end 24 is reduced in diameter providing a peripheral shoulder 25. The reduced end 24 is positioned opposite the flattened portion 27 so that the secondary supply of fuel is dispersed or splashed causing it to envelop the entire fuel rod. A spinner 26 is mounted in purposes. The direction'inwhich the flame of-the ig-. entering h o g h o r pp blades The fuel nition charge is directed into the flame cone ischosen' 's'oasnot' to disrupt the fuel-rod, the .flame of the igni- 'tion charge travelling in thesarne'direction as the-fuel,

rod.

stream of fuel. :The purpose. of the swirling action is to completely surround the' rod-like stream of fueland, prein the flame cone by the injeYctoraction-of the fuel-rod I heing'ejected therethrough at high speed. Air from outside the front end of the flamethrowerflows through.

the gap a between the shroud 10 and flame'cc-ne 11 and over the outside of the flame cone 11 into the space behind the'air-dire'cting and: fiameholding jmember- I The air enters it behind the end'of the nozzle as indicated'by the: arrows in FIG. 1.

In order to give the air a 'whlrling motion and aid in, preventing the flame from spreading back from. the. flame cone, the flame holdermember 29 is mounted on the back of the flame cone 1-1 and extends radially inwardly toward the nozzle. I The member 29 as shown in FIG. 5 comprises a sheet metal ring 30 cut partway through from: oneedge at, a I

plurality of points, the cut portions being bent at right I angles to. the ring and-twisted to form overlapping blades 30a. The ring of metal is: flattened on one. side to. lie

over and against the flattened portion 13:: of the flame I cone and is riveted thereto. -The inwardly projecting blades are cut away at theilocation oftheigniter 28..

While a common ignition means is indicated which ig- I I -=nites the propellant grain pressurizing the tank of the flame thrower simultaneously with the ignition. of the secondary fuel injected into the flame cone, the igniter- I for the. secondary jet may --be fired by electrical glow plug means and may be provided as a. separate ignite:

, from that for the propellant tankpressurizing device, the:

-.-separate: igniters being controlled by one trigger thus enabling a straighttank to be arsed,- or a tank containing fuel put under pressure by acompre'ssed gas-might be used,.the trigger-operated igniter serving only to ignite the secondary fuel: jet in the flame cone.

The flame in the flame cone is maintained in a swirling path in contact with the fuel rod issuing from the nozzle and remains in contact with the surface of the rod for a distance sufficient to ignite the surface of the fuel rod which travels through the air burning only on its outer surface to a point at which the decreasing speed of the fuel rod end due to air resistance and vaporizing of the fuel toward the end of the fuel rod due to its continued surface burning causes scattering of the end into droplets resulting in dropping of the fuel rod end unless the fuel stream impinges against a target. On impingement, the burning stream splatters and envelops the target in flame.

Operation Initially all openings in the shroud nozzle and igniter are closed by means such as plugs or discs which are blown out of place when the trigger of the flame thrower is operated to cause ignition of the gas generator. Pressure is thereafter immediately applied to the tank, forcing a concentrated stream of fuel or fuel rod through the nozzle and flame cone and projecting it from the flame thrower. The secondary stream of fuel is emitted from the reduced end 24 after it is dispersed or broken by the whirling spinner 26 and still being under the pressure of the source from which it was received, it is forced against the flattened portion 13a. The dispersed secondary supply of fuel splashes or disperses within the flame-containing housing to surround the rodlike stream of fuel and simultaneously is ignited by the charge emitted by the igniter element 28. This envelope of flame composed of ignited particles of the secondary fuel tend to be swirled by the swirling action of the inclined direction of the restricted orriiice 24 striking the flattened portion 130 plus the swirling action of the air vent mere partial ignition of the main stream of fuel. Ignition devices which .do not. completely envelop the main stream of fuel enhance'the possibility of partial ignition and reduce the efliciency of the entire flame throwing'purpose. I I.

A preferred embodiment of invention has been I specifically described and shown in the accompanying drawings. by way of illustration. but not aslimitative of the invention since various modifications may be-made in the described embodiment by those skilled in the art I without. departing .fromthe. scope of the invention. as

defined by the appended. claims.

I claim: I I 1. Ina flame thrower; means for igniting and projecting a concentrated streamof pressurized fuelcomprising: I I

a source of pressurized fuel; a fuel nozzle in supplying I relationto said pressurizing fuel and adapted to project; a

rod-dike streamoffuel; a 'fiame'c'oritainin'g housing surrounding said nozzle and projecting beyond the end means to disperse said secondary supply of fuel to completely' surround said-rod-li ke stream of fuel; means for thereof; means for projectingasecondary supplyof fuel into said housing at an angle to the axis of-the fuelnozzle; I

initiating ignition of said secondary supplyof fuel toproe I duce flame within said housing surrounding the rod-like stream of fuel adjacentits exit from the nozzle .to effect surface ignition .of'said rod-like stream:

of fuel; and,

means providing for the flow of air into said housing to.

maintain the combustion .of said secondary fuel.

'2. In a flamethrower, meansfor igniting and proiect- I I ing a concentrated stream of pressurized fuel comprising:

a source of pressurized fuel; a fuel nozzle in supplying relation to said pressurized'fuel and adapted to project. a. I I I rod-like stream of fuel; a flame-containing conical housing I I I I surrounding said nozzle and having an opening at the narrower end thereof positioned to surround the rod-like stream of fuel at a point spaced beyond the exit of the fuel from the nozzle and the wider end of the housing surrounding said nozzle; means projecting a secondary sup ply of fuel into said housing; means to disperse said secondary supply of fuel to completely surround said rodlike stream of fuel; means for initiating ignition of the dispersed secondary supply of fuel to produce flame within said housing surrounding the rod-like stream of fuel adjacent its exit from the nozzle to effect surface ignition of said rod-like stream of fuel; and means providing for the flow of air into said housing to maintain the combustion of said secondary fuel.

3. In a flame thrower, means for igniting and projecting a concentrated stream of pressurized fuel comprising: a source of pressurized fuel; a fuel nozzle in supplying relation to said pressurized fuel and adapted to project a rod-like stream of fuel; a flame-containing conical housing having an opening at the narrower end thereof positioned to surround the rod-like stream of fuel at a point spaced beyond the exit of the fuel from the nozzle and the wider end of the housing surrounding said nozzle; an annular member projecting inwardly from said wider end of the housing and formed to provide blades causing whirling of air entering the wider end of the housing; means projecting a secondary supply of fuel into said housing; means to disperse said secondary supply of fuel to completely surround said rod-like stream of fuel; means for initiating ignition of the dispersed secondary supply of fuel to produce flame within said housing surrounding the rod-like stream of fuel adjacent its exit from the nozzle to elfect surface ignition of said rod-like stream of fuel; and means providing for the flow of air into said housing through said blades to maintain the combustion of said secondary fuel.

4. In a flame thrower, means for igniting and projecting a concentrated stream of pressurized fuel, comprising: a source of pressurized fuel; a fuel nozzle in supplying relation to said pressurized fuel and adapted to project a rod-like stream of fuel; a shroud enclosing said nozzle and provided with an opening through which an ignited stream of fuel is projected; a conical flame containing housing surrounding said nozzle and projecting beyond the end thereof having an opening at the narrower end thereof positioned within but spaced from the perimeter of the opening in the shroud affording an opening for the free passage of air between said shroud and said housing and positioned to surround the rod-like stream of fuel at a point spaced beyond the exit of the fuel from the nozzle and the wider end of the housing surrounding said nozzle; an annular member mounted on the wider end of said housing and projecting inwardly therefrom and formed to provide blades causing whirling of air entering the space between the perimeter of the opening in the shroud and the outer surface of said housing and entering the wider end of the housing; means projecting a secondary supply of fuel into said housing; means to disperse said secondary supply of fuel to completely surround said rodlike stream of fuel; means for initiating ignition of the dispersed secondary supply of fuel to produce flame within said housing surrounding the rod-like stream of fuel adjacent its exit from the nozzle to effect surface ignition of said rod-like stream of fuel; the combustion of said secondary fuel being maintained by the air entering the wider end of the flame housing.

5. In a flame thrower, means for igniting and projecting a concentrated stream of pressurized fuel, comprising: a source of pressurized fuel; a fuel nozzle in supplying relation to said pressurized fuel and adapted to project a rod-like stream of fuel; a conical flame containing housing surrounding said nozzle and having an opening at the narrower end thereof positioned to surround the rod-like stream of fuel at a point spaced beyond the exit of the fuel from the nozzle and the wider end of the housing surrounding said nozzle behind the forward end of the nozzle; said nozzle having a passage through the wall of said nozzle diverting a portion of the pressurized fuel supplied to said nozzle and delivering said diverted fuel as a spray into said housing; means to disperse said portion of pressurized fuel to completely surround said rod-like stream of fuel; means for initially igniting the dispersed spray of fuel to produce flame in said housing surrounding the rod-like stream of fuel adjacent and after its exit from the nozzle; and means providing for the flow of air into said housing to maintain the combustion of said spray of fuel.

6. In a flame thrower, means for igniting and projecting a concentrated stream of pressurized fuel, comprising: a source of pressurized jelled fuel; a fuel nozzle in supplying relation to said pressurized jelled fuel and adapted to project a rod-like stream of fuel; a conical flame containing housing surrounding said nozzle and having an opening at the narrower end thereof positioned to surround the rod-like stream of fuel at a point spaced beyond the exit of the fuel from the nozzle and the wider end of the housing surrounding said nozzle behind the forward end of the nozzle; said nozzle having a passage extending axially through the nozzle and communicating with said source of pressurized fuel; the wall of said nozzle having a passage therethrough and communicating with said source of pressurized fuel, and spinner means located in said latter passage whereby the fuel flowing through said passage is delivered as a whirling spray into said flame housing; means to disperse said source of pres surized fuel flowing through the passage in the said wall of said nozzle to completely surround said rod-like stream of fuel; means for initially igniting the dispersed spray of fuel to produce flame in said housing surrounding the rod-like stream of fuel adjacent and after its exit from the nozzle; and means providing a flow of air into said housing to maintain the combustion of said spray of fuel.

7. In a flame thrower, means for igniting and projecting a concentrated stream of fuel as set forth in claim 6 and in which said latter passage is arranged to direct the whirling spray of secondary fuel against the inner surface of said housing.

8. In a flame thrower, means for igniting and projecting a concentrated stream of pressurized fuel comprising: a source of pressurized fuel; a fuel nozzle in supplying relation to said pressurized fuel and adapted to project a rod-like stream of fuel; a flame containing housing surrounding said nozzle and projecting beyond the end thereof; means for providing a flow of air into said housing to maintain the combustion of said spray of fuel; means projecting a secondary supply of fuel into said housing; a flattened portion of said flame-containing housing being aligned with said projecting means for said secondary supply fuel whereby said secondary supply of fuel is dispersed in said flame-containing housing completely surrounding said rod-like stream of fuel; and an ignition member adapted to direct a flame into said housing to initially ignite the secondary fuel in said housing.

9. In a flame thrower, means for igniting and projecting a concentrated stream of fuel comprising: a source of pressurized fuel; a fuel nozzle in supplying relation to said pressurized fuel and adapted to project a rod-like stream of fuel; a flame containing housing open at each end and surrounding said nozzle and projecting at its forward end beyond the forward end of said nozzle; means projecting a secondary supply of fuel into said housing; a flattened portion on said flame-containing housing being aligned with said projecting means for said secondary supply of fuel whereby said secondary supply of fuel is dispersed in said flame-containing housing completely surrounding said rod-like stream of fuel; and an ignition member arranged to direct a flame into said housing in a direction to ignite said secondary fuel but to prevent disruption of said rod-like stream of fuel and means providing a flow of air into said housing to maintain the combustion of said spray of secondary fuel.

10. In a flame thrower, means for igniting and projecting a rod-like stream of fuel, comprising: a source of pressurized fuel; a fuel nozzle in supplying relation to said pressurized fuel and adapted to project said rod-like stream of fuel; a conical open ended flame containing housing surrounding said nozzle with its narrower end projecting beyond the forward end of the nozzle; said nozzle having a passage inclined at an angle to the direction of said rod-like stream of fuel and delivering a spray of secondary fuel into said housing; a flattened portion of said flame-containing housing being aligned with said secondary fuel positioned substantially parallel to said rod-like stream of fuel; an ignition means arranged to direct a flame for combustion of said spray within said housing in a direction preventing disruption of said rodlike stream of fuel; and means providing a flow of air into said housing to maintain the combustion of said spray of secondary fuel.

11. Means for igniting and projecting a rod-like stream of fuel, as set forth in claim 10 and in addition comprising: means to establish a flow of air from outside the forward end of said coneshaped housing and guiding it into the back of the housing with a whirling motion.

12. In a flame thrower, means for igniting and projecting a concentrated stream of pressurized fuel comprising: a source of pressurized fuel; a fuel nozzle in supplying relation to said pressurized fuel and adapted to project a rod-like stream of fuel; a flame containing housing surrounding said nozzle and projecting beyond the end thereof; means for projecting a secondary supply of fuel into said housing at an angle to the axis of said nozzle; a splash plate contained by said flame-containing housing being aligned with said projecting means for said secondary supply of fuel and having a position substantially parallel to said rod-like stream of fuel whereby said secondary supply of fuel will envelop said rod-like stream of fuel; means for initiating ignition of said secondary supply of fuel to produce flame within said housing and surrounding the rod-like stream of fuel adjacent its exit from the nozzle to elfect surface ignition of said rod-like stream of fuel; and means providing for the flow of air into said housing to maintain the combustion of said secondary fuel.

13. A flame thrower comprising: a pressurized fuel source, a fuel nozzle in supplying relation to said fuel source, said nozzle having a main passage adapted to project a rod-like stream of fuel, a comically-shaped housing surrounding said nozzle and having its axis substantially concentric with said rod-like stream of fuel and having a passageway for said stream of fuel positioned with its diverging portion forward of said nozzle, a means for introducing a flow of air adjacent to said rod-like stream of fuel and having a swirling motion, said nozzle having a second passage adapted to project a secondary supply of fuel and in supplying relation with said fuel source,

said nozzles second passage terminating in anorifice projected at an angle to the direction of said rod-like stream of fuel, a splash plate received by said housing aligned with said nozzle orifice and positioned to deflect said secondary supply of fuel in a swirling motion around said rod-like supply of fuel, and means to ignite said secondary supply of fuel.

14. In the flame thrower as set forth in claim 13 in which said air flow introducing means is a plurality of blades in said housing.

References Cited in the file of this patent UNITED STATES PATENTS 1,304,710 Seidler May 27, 1919 1,797,654 Grund Mar. 24, 1931 2,480,147 Letvin Aug. 30, 1949 2,497,939 Garraway et a1. Feb. 21, 1950 2,574,495 Parker Nov. 13, 1951 2,669,296 Stillman et al Feb. 16, 1954 2,701,608 Johnson Feb. 8, 1955 2,857,961 Brown 111 et a1. Oct. 28, 1958