US2971325A

US2971325A - Jet propulsion device for operation submerged in water

Info

Publication number: US2971325A
Application number: US27574A
Authority: US
Inventors: Calvin A Gongwer
Original assignee: Aerojet General Corp
Current assignee: Aerojet Rocketdyne Inc
Priority date: 1948-05-17
Filing date: 1948-05-17
Publication date: 1961-02-14
Anticipated expiration: 1978-02-14

Description

Feb. 14, 1961 c. A. GoNGwER 2,971,325

JET PROPULSION DEVICE FOR OPERATION SUBMERGED IN WATER Filed May 1'?, 1948 2 Sheets-Sheet 1 INVENTOR.

CALVIN GONGWEI? A TTRNE Y Feb. 14, 1961 c. A. GoNGwER JET PROPULSION DEVICE FOR OPERATION SUBMERGED IN WATER Filed May 1'7, 1948 2 Sheets-Sheet 2 cm3: z mmm. ||||11||.||W

SPECIFIC IMPULSE INVENTOR.

CAL VIN AQ 60A/@WER 5). JMJ Ly,

ATTORNEY JET PRIPULSN DEVICE FOR (PPERATION SUBMERGED IN WATER Calvin A. Gongwer, Azusa, Calif., assigner, by mesne assignments, to Aerojet-General Cnrporatien, Cincinnati, Ohio, a corporation of @hin Filed May 17, 1943, Ser. No. 27,574

7 Claims. (Cl. oil-35.5)

This invention relates to jet propulsion and more particularly to subarmine vessels such as torpedoes operated under water by jet propulsion.

The principal object of this invention is to provide a submarine vessel or torpedo driven by reaction and capable of satisfactory propulsion even when operated at great depths of submersion.

The usual torpedoes or" the type known up to the present time are subject to limitations of the depth of submersion at which they may be operated satisfactorily. Although such torpedoes have been very eiciently propelled at depths of a few feet, or even 2O or 30 feet, the eciency of their propelling mechanism has been seriously reduced at much greater depths such as around 100G feet. At such great depths, the specific thrust, that is the pounds of thrust per pound of fuel per second, falls oft to such a small fraction of the specicimpulse or thrust obtainable at shallow depths, as to render impractical the operation at the extremely great depths. 'Ihis has been explained by the fact that the water pressure is so great at the great depths as to create an extremely high back pressure acting upon the driving engine; and this high back pressure prevents elfective expansion of the working gases which are issued from the engine.

ln accordance with my present invention, I overcome this diiculty inherent in the operation of the previously known torpedoes or submarine vessels; and I provide a device which is capable of very effective operation at great depths. In fact it is capable of operating even better at increasingly great depths of submersion than near the surface. I carry out my invention by provision of a channel or path by which water from the surrounding medium enters at a mouth and leaves through an exhaust nozzle at the rear. In accordance with a salient feature of my invention, I generate steam in a steam or reaction chamber under a considerable pressure, and I pump some of this steam into some of the incoming water from the medium in such a manner as to force it into the reaction chamber to continue the generation of steam.

The steam is formed from the water entering the reaction chamber by injecting into the chamber a water reactive material which spontaneously reacts upon striking the water to develop great heat and thereby produce the steam. For the water reactive material, I prefer to use a molten metal such as molten lithium, magnesium or aluminum; and preferably oxygen is supplied at the same time to burn any free hydrogen to steam.

A large bulk of the water entering the device from the medium is sent through the vessel to the rear where it enters an exhaust nozzle for ejection at high velocity to produce the force of reaction. In accordance with a further feature, I step up the velocity of the ejected water by the force of the high velocity steam ejected from the steam chamber into the water.

In accordance with a further feature, I provide a steam pump causing at least some of the steam from the charn- 2,973,25 Patented Feb. 1.4, 196i ber to pump against the water to augment its velocity.

In accordance with preferred features, the steam pumps which I use both for pumping water into the steam chamber and for pumping it out of the steam chamber and into the exhaust nozzle, are of the injector type comprising velocity augmenters.

A salient feature of the arrangement is that much or all of the steam condenses upon mixing with the water near the exhaust nozzle thereby creating an extremely low pressure at the place where the rearwardly owing column of water enters the exhaust nozzle.

Since the direction of flow of both the water and the steam are in the same general rearward direction, the two masses of fluid impinge with each other in an impact in which the rearward momentum existing in the steam and water before the impact is conserved and aggregated in the mass of moving water after the impact. rIhis results in a great increase of the thrust of the steam jet.

The phenomenon that the elliciency is as great and even greater at great depths than at shallow depths resides in the fact that the back pressure againstkthe steam jet from the steam chamber at the place of impingement of the jet with the water column, is very low. This back pressure is deteremined largely by the temperature of the water which is condensing the steam. The difference in pressure of the water of the medium from the pressure at the rear of the steam jet increases at increasing depths, and therefore the spouting velocity of the water before impact is increased. This causes less kinetic energy to be lost by the steam on impact with the water.

The foregoing and other features will be better understood with reference to the following detailed description and the accompanying drawings in which:

Fig. l shows a cross section view of the device according to my invention;

Fig. 2 shows a cross section view taken through the device on the line 2-2 of Fig. l;

Fig. 3 is an enlarged view of the reaction chamber, conduits and injector pump;

Fig. 4 is a cross section view taken on the line 4-4 in Fig. 3; and

Fig. 5 is a graph showing the operation of my novel device at varying depths comparing its operation with that of standard torpedo under the same conditions.

Figs. l to 4 show a torpedo ll having a streamlined outer shell 10 which diverges to larger diameters rearwardly from the mouth to a maximum diameter, and then converges to smaller diameters to the rear. The shell has an entry opening 12 located at its forward end and an exhaustnozzle 13 forming the rear exit opening. A conduit or tube 14 extends from the entry opening 12 rearwardly through the torpedo along its longitudinal axis. The tube preferably increases slightly in diameter from the mouth to a position 15, from which it extends rearwardly at a substantially uniform diameter to a position 15a; where it further enlarges in the Vform of a frusto-conical section I6 having joined to it a cylindrical conduit section 17 of larger diameter than section lli. The rear of the section 17 is within the reducing diameter of the shell llt), and abuts an internal shoulder 9 of the shell. Rearward of this shoulder, the shell forms what is approximately a frusto-conical portion 18. At the rear portion 18, the shell reduces in its internal diameter, forming a shoulder 19, a further reducing section 2li and a converging-diverging form of tubular section 22 having a minimum diameter or throat at 23. The rear end of tube 22 is the rear outlet 13.

There is supported concentrically within cylindrical portion 17 by vanes 25, a housing 24, preferably somewhat bullet-shaped in front at 24a and hollow at the rear.

The center of the forward portion of reaction chamber support 24 is provided with an axial bore 27 that terminates in a chamber 28 located in the forward portion of reaction chamber support 24. Beyond chamber 28 're action chamber support 24 is provided with a convergingdiverging nozzle 29 preferably located symmetrical to the longitudinal axis of the supporting member. The hollow rear end 31 of reaction chamber support 24 extends far enough forwardly to meet the rear of nozzle 29.

A cylindrical-shaped reaction chamber 30 is introduced into cylindrical end 31 and secured by suitable means such as welding, brazing, etc., at 30a. The forward end of reaction chamber 30 is provided with a central opening 32 to allow for discharge from the rear end of nozzle 29; and this occurs through an injector orifice 52 placed over opening 3,2. A second orifice 34 is positioned in the forward end of the reaction chamber 30 at a point where it will connect with a conduit bore 35running longitudinally through member 24 from chamber 28 to chamber 30. The rear end of the reaction chamber 30 is provided with a converging-diverging nozzle 33, preferably centrally located, through which the major portion of the products of reaction escape rearwardly from the reaction chamber.

A pair of nested frusta-

conical nozzles

38 and 39 are positioned in back of and in line with the outlet from nozzle 33; and the

nozzles

38 and 39 are placed to provide a small annular space or orice 40 between their corresponding conical surfaces, the small end of nozzle 38 being located to extend a short distance just downstream of and within the large end of nozzle 39. A cylindrical shaped closure member 41 connects the large ends of the two nozzles, forming an annular chamber 42 which is larger in cross sectional area than the area of the conical orifice 40 between the two frustums. A short conduit 37 connects a rear part of reaction chamber 30 with the annular chamber 42.

The assembled frusto-

conical nozzles

38 and 39 are positioned so that the inner surface of nozzle 38 approaches, but does not touch, the end of reaction chamber nozzle 33 leaving an annular orice 43 of sucient cross section to permit free ow of the water into the frusto-

conical nozzles

38 and 39. The rear end of nozzle 39 is preferably positioned in the frusto-conical reducing section 20 formed in the shell of the torpedo so as to form a narrow orifice 44 between theV ends of augmenter nozzle 39 and the wall of the reducing section. RearwardV of this place the section 20 enters a combining tube 22 which reduces gradually in cross section until it reaches the throat 23 from which point the passageway diverges slightly for the remainder of the distance to the exhaust opening 13 making the diameter at orice 13 slightly larger than at throat 23.

The converging portion of the combining tube 22 reduces in area to compensate for the reducing volume of the lluid stream as steam from the reaction in the reaction chamber (described in greater detail hereinafter) condenses while traveling down the combining tube to throat 23. Beyond this point the slightly increasing area raises the pressure of the liquid so that it is returned to the surrounding medium through orice 13 at a pressure approximating that existing in the surrounding medium.

A steam injector pump 45 is mounted in chamber 28 formed in reaction chamber support assembly 24; this pump being for the purpose of causing steam from the reaction chamber to mix with incoming water and forcing the mixture of steam and water into the reaction chamber against the pressure in the latter chamber. The pump comprises a converging-diverging nozzle 46 which discharges steam coming through it from conduit 35 into the wide end of an augmenter nozzle 47, which is nested with a second augmenter nozzle 48, the annular gap 21 between

nozzles

47 and 48 being connected to conduit 45 by a branch conduit 49. Nozzle 48 discharges into the converging portion 50 of the converging-diverging outlet 29; the converging portion 50 continuing to reduce until it reaches the throat 51 at which point the nozzle begins to expand slightly, terminating in an injector orifice 52. This orifice is positioned to discharge the stream of steam and Water into the reaction chamber 30, substantially following the longitudinal axis of the chamber as shown in Fig. 3.

Although the particular pump illustrated in the drawing is shown as a single stage steam injector pump, it will be understood that some other form of injector pump could be used instead, if desired, such as a multiple stage steam injector pump.

A conduit 55 enters the reaction chamber 30 at an angle to intersect the stream of steam and water entering through nozzle 52 and supplies oxygen under pressure from a tank 56, the direction of the stream being controlled by the position and direction of the nozzle 57. A second conduit 58 leads from a storage tank 59 containing a molten metal, such as molten lithium, to the reaction chamber, the metal entering the chamber through a nozzle 60 at such a position and angle that the uid stream flowing through it intersects the point at which the oxygen and water streams meet.

The oxygen and molten lithium are forced into the reaction chamber against the existing chamber pressure by means of a suitable pressure source such as, for example, a tank 61 of compressed inert gas, such as helium or argon.

To melt and keep the metal in tank 59 in liquid form, any of a number of expedients may be used. For example, strip resistance heaters (not shown) capable of being connected to an outside source of electrical energy may be wound around the outer surface of the metal tank; and the source of electrical energy may be located in a mother vessel. Since the metal container is within the torpedo it is easy to insulate the container and prevent excessive radiation.

The device operates as follows: Prior to launching the torpedo, the metal in container 59 is heated until it is melted and superheated to the desired degree. The specific heat of the metal, as well as the insulation surrounding the molten metal tank and conduit system, is suicient to insure delivery of the metal in molten condition to the reaction chamber during the entire operation of the jet propulsion device. Launching may be accomplished in a conventional manner and at the time of launching, gas under pressure in tank 60 is released through valve 62 to pressurize

tanks

56 and 59. This forces streams of the materials through

conduits

55 and 58 respectively into the reaction chamber. Water enters the reaction chamber through conduit 27, chamber 28 and nozzle 29, as well as from the rear end 13 through the nozzle 33; and when the molten metal and oxygen strike this water, violent reaction occurs, developing large quantities of steam and heat. A portion of the steam is tapped from the reaction chamber through conduit 35 and starts the operation of the steam injector pump 45 which will pressurze the water within chamber 28 and inject it into the reaction chamber through nozzle 52 against the existing chamber pressure.

Since the stream of Water, molten metal and liquid oxygen strike each other in the forward central portion of the reaction chamber, the major portion of the reaction takes place before the metal has had an opportunity to travel very far downstream in the reaction chamber. Any particles of the hot metal that leave the point of impingement unreacted will therefore generally be reacted before they leave the reaction chamber.

The Water introduced into the reaction chamber by the injector plump is preferably in excess of the amount required for complete reaction. The major portion o-f the water entering through the conduit 14 tlows around the reaction chamber vthrough annular cylindrical conduit 17 and cools the reaction chamber. This water is delivered aaviae Yto the rear-of the reaction chamber where it is drawn into

annular orifices

43 and 44 and acted upon by the Ysteam passing through principal nozzle 33 and also ,the surrounding medium, being in the order of one or two pounds per square inch absolute.

If the device is operated at any appreciable depth of submersion, the pressure at the entrance to the mixing tube will be lower than the pressure of the surrounding medium; therefore, water will lenter the mouth and scavenge the device more rapidly, making it possible to exhaust -a larger volume of water through 'the rear opening than normally would take placeif the ambient pressure were lower. (Water will not back up from the medium into the exhaust nozzle, because the nozzle is so shaped, as explained above, that the pressure is brought up from the low pressure area at the front o-f the nozzle, to approximately the pressure of the medium at the rear of the nozzle.) This phenomena explains why the operating efficiency of the device improves with increasing depth. The incoming water under pressure gushes through the nozzles atgreat velocity increasing the ehiciency of the impact between the steam and water.

Fig. 5 graphically shows the performance of the steam injector combination for underwater propulsion as a function of the depth and speed.

Curve A represents the performance of a standard torpedo operating at 80 knots, with no cavitation assumed; the combustion pot pressure being assumed to be 800 pounds per square inch absolute.

Curve B is plotted to show the operation of my novel device where mols of excess water are supplied to the reaction chamber; the duty of the propulsion injector (in pounds of condensing wa-ter to pounds of steam in the jet) is taken as and the velocity of the unit is 80 knots.

Curve D is also plotted on the basis that 10 mols of excess Water are supplied to the reaction chamber; `the duty of the propulsion injector is also taken as l5 and the velocity of the unit is zero.

In curve C l5 mois of excess water are supplied to the reaction chamber; lthe duty of the propulsion injector is fixed at l5 and the velocity is 80 knots.

In curve E l5 mols of the the excess water are supplied to the reaction chamber; the duty of the prop-ulsion injector in pounds of condensing water/ pound of steam in the jet is fixed at l5; and the velocity is zero.

From the curves B, C, D and E it is readily seen that the specific impulse, that is, lbs. thrust/lb. fuel/sec., improves with increasing depth up to and beyond 200() feet submersion, whereas, the specific impulse of a prior known type of torpedo operating in the conventional manner (curve A) appears to be highest at surface conditions and drops oif sharply at increasing depths, becoming practically negligible below 1500 feet submersion.

'The preferred method of operating the device is to have the products of reaction contain only steam with a small amount of solid metal hydroxide; and the exhaust stream should preferably contain a minimum of uncondensable gases. Such an exhaust insures quiet operation making it possible to employ sensitive sonic homing devices in the nose of the torpedo, greatly improving its usefulness for attacking and destroying enemy installations.

Likewise the fact that the wake does not contain any uncondensable gases permits the device to operate noise- 6 lessly through the water making it easier to avoid detection by acoustic pickup devices located in'enemy targets. It leaves no bubbly wake'and the bonly'noise that can be detected is the so-called cavitation rattle that takes place in the combining region of'the injectors. Since these regions are situated we ll within the body ofthe torpedo in the reaction chamber,`the noise can beeasily soundproofed by standard methods.

I claim:

1. A jet propulsion device'for operation in a water medium comprising a housing havinga'n intake opening and an exhaust opening, said housing 'containing a water duct connecting said 'intake 'opening and said exhaust opening, a reaction chamber provided with an exhaust nozzle positioned withinsaid duct, a steam injector pump having its entrancein'communication with the duct and having its'outlet'dischargingtinto saidreaction chamber, conduit means leading from said lreaction chamber to said steam injector -vpump for supplying steam into said pump, a plurality of nested frustoconical nozzles having the forward 'nozzle substantially surrounding said reaction chamber 'exhaust nozzle with the rearward frusto-conical nozzle positioned to discharge into a converging-diverging mixing tube entering said exhaust opening, the converging-portion of said mixing tube being designed to reduce in area as it progresses toward its narrowest section to compensate for the decrease in volume resulting from the j condensation of the steam passing uncondensed through the rearward frusto-conical nozzle into said mixing tube, conduit Vmeans for supplying a portion of the products of reaction from the reaction chamber to the region between said forward and rearward frusto-conical nozzles, water entrance means from the duct into the nested frustoconical nozzles so that Water is drawn into the nozzles from the duct by action of the steam passing through the nozzles, and conduit and injector means for supplying liquid water reactive fuel to the reaction chamber and conduit and injector means for supplying oxygen to said reaction chamber.

2. A jet propulsion device for operation in a water medium according to claim 1 in which the diverging portion of the mixing tube increases in cross section to elevate the pressure of the column of water flowing therethrough to approximately the pressure of the surrounding medium.

3. A jet propulsion device for operation in a water medium comprising a housing havingan inlet opening and an exhaust opening with a passageway for water to flow through the housing from the inlet opening to the exhaust opening, a reaction chamber within the housing in communication with the passageway, a conduit for introducing a water-reactant substance into the reaction chamber to produce steam therein, a steam in 4jector pump connected with the reaction chamber to receive some of the steam generated in the chamber, a conduit connected between an inlet of the steam pump and the passageway for sending water from the passageway to the pump to mingle with the steam so that the water is pumped into the reaction chamber to carry on the reaction, a steam nozzle connected at the outlet of the reaction chamber through which steam is ejected therefrom, a steam pump coupled with the output of the nozzle, entrance means at the steam pump for enabling water flowing through the passageway to enter the lastmentioned pump, whereby the steam velocity increases the water ow through the passageway, and the steam condenses into water to create a reduced pressure in the region at the outlet of the last-mentioned pump, and a converging-diverging nozzle leading from the outlet of the last-mentioned pump to the exhaust opening.

4. A jet propulsion device for operation in a water medium comprising a housing having an inlet opening and an exhaust opening with a passageway for water to llow through the housing from the inlet opening to the exhaust opening, said passageway having an enlarged region, a reaction chamber and a steam injector pump within the enlarged region said pump having an outlet in communication with the reaction chamber, a conduit for introducing a water reactive substance into the reaction chamber to produce steam therein, a connection from the reaction chamber to the steam injector pump to introduce steam from the chamber into the steam injector pump, a conduit communicating from the passageway to the steam injector pump for sending water to the pump to mingle with the steam so that the water is pumped into the reaction chamber to carry on the reaction, a steam nozzle connected with the reaction chamber through which lsteam is ejected from the chamber, a second steam injector pump coupled with the output of the nozzle, Water entrance means at the second steam pump for enabling water owing through the passageway to enter the last-mentioned pump, whereby the steam velocity increases the water flow through the passage- 20 way, and the steam condenses into water to create a reduced pressure in the region at the outlet of the second pump, and a converging-diverging nozzle leading from the outlet of the second pump to the exhaust opening.

5. A jet propulsion device according to claim 4 in which the outlet from the first-mentioned' pump is connected with the combustion chamber by a converging-diverging nozzle.

6. A jet propulsion device according to claim 4 in .which the steam nozzle is at the rear of the combustion chamber and the first-mentioned steam injector pump is in front of the reaction chamber, and the conduit carry- 'ing water to said first-mentioned pump extends from a position at the passageway in front of said first-mentioned pump. Y Y

7. The method of driving through waterfa jet propulsion device of the type having an entryopening, an exhaust opening and a water duct between said openings, which comprises: by-passing some kofthe water flowing through the duct into a reaction region, introducing water ,reactive fuel into the reaction region, -thereby generating steam, steam-pumping ,thenwater into said reaction region with some of said steam, exhausting the remaining steam from the chamber, steam-pumping the Water ,in the duct tothe exhaust opening, and mixing the exhausted steam with the pumped water, condensing the steam mixed with the pumped water thereby reducing the pressure, then increasing the velocity of the water down- ;'stream from the place of steam condensation .and then raising the pressure of the owing water to that of the' surrounding water medium as the water from the duct meets that of the medium.

References Cited in the tile of this patent UNITED STATES PATENTS Great Britain Apr. 19, 1934