US2500334A - Jet motor operable by monopropellant and method of operating it - Google Patents

Description

JET MOTOR 2,500,334 OPERABLE BY uoNoPRoPELLAN'I:

AND METHOD OF OPERATING IT 2 Sheets-Sheet 1 Filed June 19, 1944 QNI mv R March 14, 1950 M. J. zucRow 2,500,334

JET MOTOR OPERABLE BY MONOPROPELLANT AND METHOD 0F OPERATING IT Filed June 19, 1944 2 Sheets-Sheet 2 76 :3gv /03 E INVENTOR. MUR/CE df ZUC'RU B Y.

CLLVQSQF ATTORNEYS a jf-aniline ,andl

Patented Mu. 14, 195o a .ET vMOTOR OPERABLE BY ltIONOl-ROPI'IL- LANT AND METHOD OF OPERATING IT Maurice J. Zucrow, Altadena, Callf., asslgnor to Aerojet Engineering Corporation, 'a corporation of Delaware- Azusa, Calif.,

Application June 19,1944, serniiirt.l 540,959

" This invention relates tolet thrust motors and methods of operating it and has for its object to 1 f-improve'L he voperating performance of such mo vhighjjvelocities Athroughl an exhaust nozzle. Liq-` ;uid fuels have heretofore been injected into the `combustion chamber against the pressure in the chamber'for this purpose. Good performance I as Vbeendfobtained by'vlnlecting two propellant liquidsinto the-combustion chamber, one a fuel andLthe'other an oxidlzer for the fuel. A'131115, anilinehas'been usd as a fuel and red fuming nitricacidas an oxidizer and these two liquids ,yfhave beenjinjecfted separately into vthe combus- 3113 tion chamber and caused to lmpinge against each jother`. Spontaneous combustion takes place upf, y.on the impingement, producing thedesired gases @which are exhausted as a jet through the ex- ".'hauvst nozzle; f i QA' disadvantage of such spontaneously combust- ;ing liquids is that they produce operation at very v@hightemperaturesof between 3000 F; and 4500 t. F., therebyitending to burn the motor when op- .erated for an appreciabletime.

:Other fuels `have been proposed for burning in @wthefchamber which produce higher jet velocities andlower-chamber temperatures than the foregoing spontaneously combustible propellants. "example, monopropellants, that is, single u vsources of propellant liquid, such as nitromethi aneor a Amixture of nitromethane and nitroeth-v f ane havefbeen used. T hese burn at the desired flower temperatures and produce the desired `jliigher jetfivvelocities, but they are not as easily f-ignitable as `the more spontaneously combustible 1 higher temperature fuels, so have required more E. special means' of igniting, for example, an elevated igniting temperature. y

.6'Clalms. (CLM-35.6)

A feature of my invention is the use of a temperature controlled valve to disconnect the starter propellants when the temperature is brought up to the desired level and then electing the second lower temperature burning propellant.

`In this .way I am enabled to obtain the easy igniting characteristics of propellants such as aniline and red fuming nitric acid and to obtain during most of the time of operation the higher jet velocities and lower chamber temperatures of the `more dimcultly ignitable propellants such as the nitroparafdns. Y

My invention will be better understood from the following Ydescription when taken in conjunction with the sheet of drawing in which:

Fig. 1 is an elevational view incross section of my invention;

Fig. 2 is an end view of Fig. l; and Fig. 3 is a cross sectional view along line 3 3 oi Fig. 1.

Similar numerals refer to similar parts in the views.

l The motor shown in Figs. 1 and 2 comprises'a spherical portion I which is the combustion chamber and an exhaust nozzle 2. The combustion chamber is made of two pieces, a hemlspherical portion 3 which is welded vto another hemispherlcal portion 5 at I. The hemispherical portion 5 is somewhat elongated containing a flange 'I Welded thereto at 6. Flange 'I contains internal threads 8 into which the exhaust nozzle 2 is screwed.' The exhaust nozzle 2 has a collar I0 provided with threads and a shoulder flange Il.

' The shoulder ilange Il is recessed as shown at I .In accordance with my 'invention'I' am able to make use of a fuel whichburns at lower temperalfature 'andhigher velocities vsuch as the monoproyj-pellan'i'." nitrometha'ne, 4by first igniting easily `spontaneously'combusted propellants and therei by heating :the chamber or a refractory member whiehfcan` be brought `up tov a temperature zrequired'toignite the lower temperature burning ffuel.. For-fexample if the initial propellants be red filming nitric acid; these can be A S-burned-for; a: couple' of seconds, long enough to Wheat the chamberfor-a refractory member in it to around 300 y perature forigniting nitromethane.4

F.which is a sulllciently high tem- I2. The wall of the exhaust nozzle 2 contracts toward a constricted portion I3 from recess I2. The constricted portion I3 ares `outwardly to an enlarged portion I4. Another flange I5 is welded tothe enlarged portion I4. The flange `lli continues substantially the general outline. of the exhaust nozzle forming a recess I6 and a thickened section I'I which provides the neces- 'sary metal for the threads of screws I 8. The flange I5 is machined to receive bolt ring I9 and machined completing the outline of the exhaust nozzle at 20. i i

In Figs. 1, 2 and 3 the exhaust nozzle is surrounded by a jacket 22 arranged to provide a uid flow spirally from the fluid inlet at the extreme end of the exhaust nozzle toward a chamber around the combustion chamber. A spiral member 2i is formed integrally with the wall of the exhaust nozzle 2 or may be welded to it. A pair of solid members and 6I are 1 placed around thel spiral at the nozzle,

the two halves being which a uid may circulate.

bolted together by bolt 52 and nut 83. Theinner curved surfaces of members60 and 6| fit against theedges' of the spiral convolution sov that the left hand side of ange33jto1which 4a. conduit l 4| may be attached in the conventional manner convolution forms a spiral passageway for vthe passage of iluidspirally around the nozzlevirom Y a iluid inlet at pipe 53' to the fluid chamber A aroundlthe combustion chamber. The convolution near the exhaust end 20 of the nozzle is made of greater height. than at the constricted throat of the nozzle.y Thus. convolution 25 is higher than convolution 24 which serves to space members 60 and 6| further from-the nozzle wall at the exhaust end than at the throat. yThus, the

area for iluid passage isgreater'atthe exhaust end than at the throat. Theouter peripheries of members 60 and 6| coincide with vthe inner surface of a jacket 22. One or a plurality of slots 21 are machined around members 60 and 6| and into each slot an ringv 2811s snapped'providingA a iluid tight contact between members 80 and u and the tubular Jacket 22.- The duid inlet is provided through a nipple`29 to the jacketat the exhaust end of the nozzle 2,'this entrance communicating with the spiralconvolution which is nearest the exhaust. The tubular jacket 22 is welded to the bolt ring I9. By inserting screws I8 through the bolt ring |9 and screwing them into the ilange l the exhaust nozzle 2 is thereby fastened to the tubular member 22.

and is welded to tubular member 32 providing a chamber A between members 5 and 35 through Another hemisphericalmember 35a is welded to the hemispherical member 35 at 10. Continuation oi' chamber A is providedbetween member-35 and member 35a. In the extreme portion of the spherical combustionl chamber I show a. multiway L 1| welded to the hemispherical mem ber 35a which is in communication by conduit with the injector valve 54, and in further communication by corresponding vconduits 56a and 55h with the other two injector valves, respectively, a part of these conduits 56a and 56h being shown in Fig. 2.

A hemispherical refractory liner 12 is placed4 into the hemispherical combustion chamber and backed by the refractory liner 13. Liners 12 and 13 are heldin place by aiige 1 and collar I0 which isscrewedinto nance 1. s

The refractory lining' may be any lof the following: tungsten. tungsten carbide, silicon carbide, vboron carbide,

calcium oxalate, carbon (graphite), magnesium oxide, molybdenum` carbide, zirconium carbide, zirconium oxide or any o other standard refractories such as .mullite, and asbestos, `or other Transito, mixture of carbon like substances. v -i l In'the upper portion of the hemispherical member 35 a tubular member 36 having amange 31 vis welded thereto; member 36 protrudes through chamber A into the hemispherical portion. 5 to, which it is also welded. y

A dual injector is provided comprising 'a' cylindrical member 38 havinga flange 39, an openving in one end and a wall/40fin the other end.

A flared nipple (not shown) is provided 'in the 75 erated which commences theziiowfof likewise welded thereto.

kis provided in boss yvalve 58 is inserted. l vided in the injector.

Vcontains an oriiice 61 intozwhicha:-va1ve681;is

an enlarged piston 69v sliding and secured thereto with 4nut 42. CA 'cylindrical member 43 having on oneend a ared portion y (not shown) and a thread below the ilare provides conventional means for attachinga yconduity 50 securing it with nutk 5|. Member-,'43 has -a-concentric vopening to the wall 44'whe're a sma1l'orii nee as 1s provided. Wall 44 is 'formed to provide an inclined surface 46 havingztwo or more oriilces 41 therein.' Wall 44 forms a horizontall surface 48. The horizontal surface 48. abuts against'the I cylindrical member 38' and is welded thereto. Member 43 passes through the'wa1l'40 and is v The whole dualain- .lector is inserted into the tubular l.member y38 and bolted to ilange 31 with 1 5 makes the connection pressureftight.

`In the lower portion of member 35 there isa` tubular boss 54 having a shouldergar'idais'mallerf yThis portion 155 .iszinserted into member y33 passingjthrough@chamber cylindrical portion.l 55.I

A into the hemispherical member Sand is-welded .to both hemispherical members 35:.and I5; :'.Bssl

54 is provided with a ared andzthreaded nipple (not shown) for connecting'a..confzivliit 56-1which is secured by nut 51. :A

54 .into which vany-.injector Injector 5801s. madef of;-h'exdown providin'gfa head: and a threaded portion which is screwedwintofthe boss 54. The head rests .against 5a' vwasherl,'s58 which makes the injector valve; 56 pressure itight. Hole 64 is drilled at assembly when.theinjector A concentric hole 65 isprorunning fto-a wal1f66 which valve 58v is screwed. agonalstock turned iltted. Valve 68 has u y y l in the concentrichole 65 and -isunder thefpres.- sure of a spring 80. The spring.. pressure maybe adjusted by an inserted set v'screwl'.y Guide 88a of the valve 68 passes throughthe-Qset screwfl.'

Although only three-injctor'-.valves arefshown it will be understood thatany number offs'uch injectors may be provided. Therel is provided avalve 52 arranged tof preventgiluid from'o'wing'. into the dual injector through yconduits 4| and 50 i when uid is ilowing into the motor throughpipe v tion respectively between ports 9|- and 94 and-rbethrough conduit l, and 50.

53; and vice versa. This valve*52comprises a valve chamber having three :inlet: ports 9|, 92

land'iii and respective outlet portsl94,-95 an'd98. The valve chamber is made slightly tapered,=fas

shown, and is provided with a. correspondingly tapered valve stem 91 held snugly in the valve chamber by means of a compression spring 98 l compressed between the top of thestem andthe' vcap 99. The valve stem is provided with three holes |00, |0| and |02.V Holes' |00 and |0|f1are parallel to each other and hole |02 Ihasit's laxis at 90 to the axis of holes |00v and-'IUI'. 'Holes |00 and |0| are adapted to provide[communica-A tween ports 92 and `9 5 as shown; when the .valve stem holes are lined up 'with-the.portsfgl-IkileV |02 is adapted to provide communicatlongfbetween portsr93 and 96 whenthe'hole;|.02zislined' up with thes'eports. When valve "handle, |03Iis turned to the position shown the;

conduits 4| and 50-.but not throughEc'onduii553.-A Turningthe valve stem 90'? `wouldprovider'fil'o'wl 53 but not th'rough'conduitsj4|-- When starting the motor'thevalve' 52Fisf`oplsmall screws 14.- A. gaskety concentric, ,threadedlliole v valvestemfis" in the angular positionto prchlidefil'ow'fthriilighl amounts of the fuel and the oxidizer. By permitting only small amounts of the fuel and oxidizer their spontaneous combustion is thereby assured. 'Ihe correct proportion should be three parts of oxidizer to one part of fuel. The oxidizer flows through conduit 4| (Fig. 2) into the 'is heated thereby. As soon as the temperature of the refractory liner 'l2 reaches the temperature required for combusting the monopropellant the valve 52 shuts oi the iiow of the fuel and the oxidizer and turns on the monopropellant which flows through conduit 53 (Fig. 2) into the convolutions of the spiral 2| (Fig. 1) and through the chamber A and is distributed through the multiple way L 1I into the respective injector nozzles. The monopropellant is injected into the combustion chamber b-y three streams which impinge at C thereby further dispersing it. When the monopropellant hits the heated refractory liner 'l2 it is combusted. The products of combustion escape through the exhaust nozzle delivering thereby the desired thrust. The thrust of the motor may be varied by manipulating a control valve 16 (Fig. 2) inserted in the monopropellant conduit between the valve 52 and the motor.

The method of leading the monopropellant through chamber A keeps the temperature of the spherical combustion chamber within 150` C. or a little above.

From the foregoing description it can readily' having at least two injection orifices, one for a fuel and one for an oxidizer, a conduit for leading fuel to the dual injector and a conduit for leading oxidizer to the dual injector and a conduit for leading the monopropellant to the inlet, a valve for closing the monopropellant conduit when the fuel and oxidizer conduits are opened and for opening the monopropellant conduit when the fuel and oxidizer conduits are closed.

4. The method of operating a thrust motor having a combustion chamber and an exhaust nozzle which comprises introducing streams of aniline and red fuming nitric acid into the chamber, and thereby spontaneously combusting them, thereafter stopping the supply of said aniline and acid and immediately thereafter combusting within said chamber a monopropellant fluid consisting of nitromethane, and exhaust-- ing the products of combustion through the nozzle.

5. The method of operating a thrust motor having a combustion chamber and an exhaust nozzle thereby spontaneously combusting them, thereafter stopping the supply of said aniline and acid and immediately thereafter 4combusting within of a mixture of nitromethane and be seen that I have provided a jet thrust motor which may operate for considerable periods of time.

I claim:

1. In combination with a .iet motor having a combustion chamber and an exhaust nozzle, a plurality of propellant injectors, at least one of the injectors having a single injection orice for injecting a monopropellant into the chamber, another of the injectors having at least two injection orifices, one for a fuel and one for an oxidizer, a conduit for leading fuel and a conduit for leading oxidizer to the last-mentioned injector, a conduit fo'r leading the monopropellant to the monopropellant injector, and a valve connected with the conduits for preventing the monopropellant from flowing through its injector when the fuel and oxidizer are flowing through their injectors and for preventing the fuel and oxidizer from flowing through their injectors when the monopropellant is flowing through its inlector.

2. A combination according to claim 1 in which means are provided for maintaining the monopropellant injector oriflce closed when the fuel and oxidizer are flowing through the dual injector.

3. In combination with a jet motor having a `combustion chamber and an exhaust nozzle, a

plurality of propellant injectors, at least one of the injectors having an injector orice for injecting a monopropellant into the chamber. a jacket around the nozzle and combustion chamber providing a cooling chamber through which the monopropellant ows to its injector, an inlet tothooooiing chamber-,anotherottheinjeot's said chamber a monopropellant iluid consisting nitroethane, and exhausting the products of combustion through the nozzle.

6. The method of operating a thrust motor having a combustion chamber and an exhaust nozzle which comprises initially heating the chamber by combusting in it a spontaneously combustible propellant fluid, thereafter stopping the supply of said combustible fluid and imme- `rliate1y thereafter injecting into the chamber a monopropellant fluid which ignites at the temperature to which the chamber has been raised, andA exhausting the products of combustion through the nozzle.

MAURICE J. ZUCROW.

REFERENCES CITED The following references areof record in the le of this patent:

UNITED STATES PATENTS Number Name Date 858,640 Welles July 2, 1907 992,891 Loop May 23. v1911 1,879,186 Goddard Sept. 27, 1932 2,010,469 Triebnigg Aug. 6, 1935 2,074,098 Adams Mar. 16, 1937 2,217,649 Goddard Oct. 8, 1940 2,243,594 De Voe et al May 27, 1941 2,273,243 Zanetti Feb. 17, 1942 2,398,201 Young et al. Apr. 9, 1946 2,433,943 Zwicky Jan. 6, 1948 FOREIGN PATENTS Number Country Date 17,696 Great Britain Dec. 17, 1915 279,770 Great Britain Nov. 3. 1927 558,934 France 1 June 5, 1923 157,231 Switzerland Dec. 1, 1932 OTHER REFERENCES Aircraft Engineering, issue oi' September 1935, Rocket Propulsion," by Willy Ley, page 228.

Aviation, issue of January 1944. "Jet Propulsion, by Willy Ley, pp. 148-149.

Certificate of Correction Patent No. 2,500,334 March 14, 1950 MAURICE J. ZUCROW It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, lline 22, for member 33 read member 35 and that the said Letters Patent shouldV be read with this correction therein that the same may conform to the record of the case in the Patent Ofce.

Signed and sealed this 18th day of July, A. D. 1950.

[SEAL] JOE E. DANIELS,

Assistant Uommsszoner of Patents.

Certificate of Correction Patent No. 2,500,334 March 14, 1950 MAURICE J. ZUCROW It is hereby certified that error appears in the printed specication of the above numbered patent requiring correction as follows:

Column 4, line 22, for member 33 read 'member 85 and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 18th day of July, A. D. 1950.

[SEAL] JOE E. DANIELS,

Assistant Uommz'ssz'oner of Patents.

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