US2753687A

US2753687A - Injection head for jet propulsion system

Info

Publication number: US2753687A
Application number: US187962A
Authority: US
Inventors: Zoltan R Wissley; George L Macpherson
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1950-10-02
Filing date: 1950-10-02
Publication date: 1956-07-10
Anticipated expiration: 1973-07-10

Description

y 10, 1956 z. R. WISSLEY ET AL 2,753,687

INJECTION HEAD FOR JET PROPULSION SYSTEM Filed 001;. 2. 1950 'F'i g. 2.

Fig.\.

Zzigfi 29 Inventor's Zoltah R. WLSSI 3 George L. MacPher-son,

Their ALtorne United States Patent INJECTION HEAD FOR JET PROPULSION SYSTEM Zoltan R. Wissley, Schenectady, and George L. MacPherson, Scotia, N. Y., assignors to General Electric Com pany, a corporation of New York Application October 2, 1950, Serial No. 187,962

2 Claims. (Cl. 6039.46)

This invention relates to an injection head for fluid reactants. More particularly, it relates to a reactant injection head for jet propulsion engines.

The term jet propulsion engine as used herein includes all so-called reaction type motors wherein the mechanical driving thrust or force is derived from the reaction of equal and opposite forces arising between the motor body and the body of reactants attained during the conversion of the reactants into gaseous products of greater volume than that occupied by the reactants as distinguished from internal combustion engines of the reciprocating type. Devices falling Within this definition and in the operation of which this invention may be em ployed are commonly known as rocket motors, turbo-jets, pulse-jets, and turbo-prop-jets. While the present injection head is, for the purpose of example, described herein as applied to a rocket motor, it will, of course, be realized that it may be used in any jet propulsion system.

Heretofore, fuel injection heads for jet propulsion motors burning fluid fuels or propellants have typically included a plurality of impinging or non-impinging holes arranged in a geometric pattern from which the oxidizer and combustible reactant issue into the combustion chamber for ignition.

The holes or passages for the emission of reactant from the injection head are usually made as short as possible and are backed up by a relatively larger space which serves in a sense as a temporary reservoir for the reactant. An inherent characteristic of such injection heads is the change of flow coefiicient at certain pressure drops. This, in turn, results in changes in the rate of flow of fluid through the holes and into the combustor. While such interruptions are only momentary, they are constantly recurrent and in a head containing a large number of holes contribute to pulsations in the combustion process. These pulsations result in an unsteady thrust which detracts from the efficiency of the motor. More serious is the fact that the pulsations initiate vibrations in the motor which may lead to mechanical failure and destruction of the motor. The lack of steady fuel feed also may cause the burning out of the injection head due to periodic excesses of oxidizer or increased heat transfer rates.

It is an object of this invention to provide an improved injection head for jet propulsion motors.

It is another object of this invention to provide an injection head for jet propulsion motors which is characterized by a smooth, non-pulsating flow of fluid.

Another object of the invention is to provide a relatively large surface area of reactant flow per reactant volume.

A further object of the present invention is to provide a jet propulsion motor which is devoid of pulsations due to interruptions in the reactant feed through the injection head.

Other objects will become apparent from a consideration of the following description and the drawing in which Fig. 1 is an elevationalview partly in cross-section of the ice present injection head, Fig. 2 is a partial top plan view of the injection head, and Fig. 3 is a view of a rocket motor with the injection head in place.

It has been found that an improved non-pulsating injection head for jet propulsion motors may be very readily provided and which is characterized by case of manufacture.

More particularly, it has been found that such an injection head may be realized by providing a plurality of slits in lieu of holes through which to inject the reactants into the combustion chamber.

The injection head slits or slots may be made in any desired geometric configuration. However, for ease of manufacture that particular arrangement or embodiment shown in the drawing is preferred.

Referring to Fig. 1, there are attached to the body portion 2 of injection head 1 inlet conduits 3 and 4 for the reactant or propellants which comprise an oxidizer and a fuel. As is well known to those skilled in the art, any of a number of oxidizers and fuels may be used in jet propulsion devices. Typical oxidizers include, among others, oxygen and hydrogen peroxide while examples of fuels are alcohol, gasoline, kerosene, and other hydrocarbon and organic and metallo-organic materials. For the purpose of the present description it will be assumed that the fuel enters through conduit 3 and the oxidizer through conduit 4, although the reverse arrangement may also be used. Oxidizer conduit 4 terminates in a chamber or header portion 5. Connecting With chamber or space 5 are a plurality of relatively large annular holes or slots 6 and 7 which extend from the chamber through the forward portion 8 of the injection head. The upper part of these annular holes is slightly enlarged as at 9 forming a shoulder 10, the purpose of which Will be made clear hereinafter.

Fuel conduit 3 terminates in annular space 11 which in turn leads to

annular holes

12, 13, and 14 which are similar to holes 6 and 7 though not necessarily of the same size. Like holes 6 and 7, the upper portions of the fuel holes are also slightly enlarged to form a shoulder such as that shown at 10. Passage of fuel from chamber 11 to hole 12 is direct while conduits, not shown, are employed to connect the chamber with holes 13 and 14, annular holes 6 and 7 being interrupted at a plurality of points to permit such passage.

The slit-like propellant feed holes 15 of the invention are provided by placing in the upper enlarged portion of the

annular holes

6, 7, 12, 13, and 14, ring members 16 which are so proportioned in width as to be smaller than the width of the annular holes by an amount which will provide slits or slit-like openings 15 of the desired width.

Rings 16 are supported at a plurality of points by small metal blocks 17 which rest on the shoulders 10 of the annular holes. Shims 18 which are conveniently of a U-shape which fit under and along the sides of rings 16 are used to maintain the proper spacing of ring 16 from the side of the annular hole. Blocks 17 and shims 18 are arranged under rings 16 at a sufficient number of points to provide adequate support to the rings, the shims preferably being welded, brazed, or otherwise fixed to the blocks. For convenience in manufacture of the present injection head, they are arranged radially as shown, the larger rings being supported at more points than those of smaller diameter which are by structure more rigid.

In order to hold the rings 16 in fixed-spaced relationship to the rest of the head, a welding bead such as that shown at 19 and 20 is laid or deposited over the rings, the upper exposed parts of the shims, and the head body between the rings. While welding as above has been found to be the most convenient way of assembling the parts concerned, the rings may also be fixed in place by brazing', bolting, or any other convenient way.

It will be understood, of course, that the number of slits proyided, for the injectiompf reactants yarieswith thesizeof the injectiorihead. As a specific examplefllie injection face of thehead shown in. thedrawing having ten annular slits is about three i nches in diameter. A ha ha. Tug M c -d ame r o en in h and ed t in .35 new a i l isi y'se a h ab e mple, has about fifteen annular slits. It will also be understood thatthewidthpf the annular slits varies depending on the size ofth'e head and the reactants used. For example, the widthot the slits in the three inch di'ameter head shown is about 0.01 inch. The oxidizer and fuel slits may also beof different widths.

, In o'peration f fe l tsrea through conduit 3 into space ll and into

annularholes

12,13, and 14 with little or no pressure drop. From these holes the fuel is fed through slits l' alongside rings 16, exlcept at those limited points which blocks 17 prevent such fl'ow. Qxidizer is fed in a similar manner through conduit 4 into header chamber f5, thence to annula r holes 6 and 7 and through slits 15. it will be noted that the only restricted passage for flow of reactant and hence the only region in which any nota- Il'e pressure drop occurs is in the very short passage through the slits themselves. The reactants issue from the slits in concentric annular sheets which lend themselves toreatly mixingfor thorough combustion. Preferably though not mandatorily, the outer slit is used to feed fuel to shield the Wallof the combustor from pure oxidizer which may cause hot spots and failure. The angle o f exit of the fuel may be varied by canting the slits. InFi'g. 3 is shown a rocket motor as typical of jet propulsion mo-tors in which thefpresent injection head may be employed Injection head 1 is fixed to rocket combustion chamber 21 by means of bolts 22 fitted through holes ZZ'; in the head and in the flange24 of the motor. The rocket motor is shown conventionally as having an inner combustor wall 25 cylindrical in its upstream portion and restricted downstream to form a throat 26 and flaring nozzle portion 27 for the issue of hot gases. In- Ilet conduit 28 and outlet conduit 29 are provided for the flow of coolant between liner 25 and the outer Wall 30 4 of the motor. A rocket motor is chosen as typical of jet propulsion devices merely for purposes of illustration and not in any limiting sense, the present injector being useful in any type of reaction motor using fluid reactants.

There is provided by this invention an improved slittype reactant injection head for jet propulsion motors which is characterized by smooth running qualities and absence of pulsations due to unsteady flow of reactants. The construction leads to ease in manufacture and results in improved combustion due to the large surface area of reactant provided per unit of reactant volume.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A reactant injection head for jet propulsion engines comprising a fuel inlet, a fuel inlet header connected to said fuel inlet, an oxidizer inlet, an oxidizer inlet header connected to said oxidizer inlet, and concentric alternate outletmeans for said fuel and oxidizer connected to the respective "headers, said outlet comprising a plurality of annual apertures having ringsfixed therein, said rings being in spaced relationship to said apertures to form slits.

r :2. A reactant injection head for jet propulsion engines comprising .a "fuel inlet, 'a fuel inlet header connected to said fuel/inlet, an oxidizer inlet, an oxidizer inlet header connected to said oxidizer inlet, and concentric alternate outlet mean rg s'aid fuel and oxidizer connected to the respective headers, said outlet means comprising a plurality of annular apertures,each aperture having fixed in the exit end thereof a ring supported at a plurality of pointsh'y meter blocks and held in spaced relationship to the edges of s'a'id apertures at the same points by metal shims to form annular slits 'in conjunction with said apertures.

Cited in the fileof this patent N UNITED STATES PATENTS 1,436,429 'weyun Nov. 21, 19 2 2,405,465 Summerfield Aug. 6, 1946 2,409,036 Goddard Oct. 8, 1946 2,482,260 Goddard 'Sept. 20, 1949 2,532,709 Goddard Dec. 5', 1950