US3533239A - Combined pulse jet and variable ram jet engine - Google Patents

Description

Oct. 13, 1970 COMBINED PULSE JET AND VARIABLE RAM JET ENGINE Filed May 8, 1969 Fig.

J. N. GHOUGASIAN 3 ,533,239

4 Sheets-Sheet 1 Jo/m IV. G'lrougasian INVENTOR.

MM FM L COMBINED PULSE JET AND VARIABLE RAM JET ENGINE Filed May a, 1969 4 Sheets-Sheet um um aw M an 1. A i; g Q} .7. mm 9 Q k k m NM N7 I V VMQN udnwln v luv, 2 Yr vnb? Q ww m. mm Mn mm mm E MN m w t m m R. m n m a N I A u E m w 1 8 M W G M w B hm K v\ an Oct. 13, 1970 J. N. GHOUGASIAN 3,533,239

COMBINED PULSE JET AND VARIABLE RAM JET ENGINE Filed May 8, 1969 4 Sheets-Sheet 5 m V (o r v John N. Ghougasian ENTOR.

BY WWW Oct. 13, 1970 J. N. GHOUGASIAN COMBINED PULSE JET AND VARIABLE RAM JET ENGINE 4 Sheets-Shet Filed May 8, 1969 John N. Ghbugasian R. m m,

I m mm United States Patent 3,533,239 Patented Get. 13, 1970 3,533,239 COMBINED PULSE JET AND VARIABLE RAM JET ENGINE John N. Ghougasian, 666 W. 188th St., New York, NY. 10040 Filed May 8, 1969, Ser. No. 822,980 Int. Cl. F02k 7/06, 7/10 U.S. Cl. 60-244 Claims ABSTRACT OF THE DISCLOSURE This invention relates to propulsion engines of the reaction type and more particularly to a reaction jet engine having pulse jet and ram jet modes of operation.

Pulse jet and ram jet engines have distinctly different geometrical configurations and components necessary to support operation in accordance with the generally known principles. Since pulse jet engines become inefficient and inoperative at speeds above 400 m.p.h., they are only suitable for operation below the higher speed ranges where ram jet engines are most efiicient. Therefore, combined pulse jet and ram jet engines have been proposed in an attempt to provide propelling thrust at both lower and higher speeds with optimum efficiency. However, engine geometry suitable for pulse jet operation is incompatible with engine geometry for ram jet operation. Further, pulse jet engines require a check valve assembly in the airstream flow path that would be intolerable for ram jet operation. Ram jet engines on the other hand require the presence of a flame holder in the airstream flow path incompatible with pulse jet operation. Combined pulse jet and ram jet engines heretofore proposed have therefore involved a plurality of airstream flow paths and flow blocking valving arrangements in order to incorporate within a single engine separate pulse jet and ram jet sections. Such combined engines involve relatively complex internal engine structure making engine operation less efiicient for both pulse jet and ram jet operational modes as well as adding to the weight of the engine.

The foregoing drawbacks of prior art proposals for combined pulse jet and ram jet engines, have been overcome by the present invention. An important object of the present invention therefore is to provide a combined pulse jet and ram jet engine which is inherently less expensive to manufacture and capable of providing a greater power-toweight ratio for both pulse jet and ram jet operation than any combined jet engine heretofore proposed.

In accordance with the present invention, the internal geometry of a reaction jet engine is altered in order to accommodate both pulse jet and ram jet operation while components respectively associated with pulse jet and ram jet operation are selectively inserted and retracted from a single airflow passage common to both operational modes. In changing the internal geometry of the engine, an important and critical feature resides in an axially shiftable nozzle throat formation which is in a forward position rearwardly limits the combustion zone for pulse jet operation and in a rearward position dimensionally enlarges the combustion zone and converts the tail end portion of the engine to an exit nozzle suitable for ram jet operation. Also, a retractable check valve assembly is positioned within the intake section of the engine for pulse jet operation while a retractable flame holder is positioned at a forward end of a combustion zone for ram jet operation. Air inflow to the engine is changed by a variable geometry intake section in order to accommodate pulse jet and ram jet operation in conjunction with the other internal engine changes aforementioned.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. '1 is a top plan view of a combined pulse jet and ram jet engine constructed in accordance with the present invention.

'FIG. 2 is a longitudinal sectional view taken substantially through a plane indicated by section line 22 in FIG. 1.

FIG 3 is a transverse sectional view taken substantially through a plane indicated by section line 3--3 in FIG. 2.

FIG. 4 is a transverse sectional view similar to FIG. 3 showing the check valve assembly being angularly repositioned for retraction.

FIG. 5 is a longitudinal sectional view through the engine converted to ram jet operation.

FIG. 6 is a sectional view taken. substantially through a plane indicated by section line 66 in FIG. 5.

FIG. 7 is a partial longitudinal sectional view of the engine showing the flame holder angularly orientated in preparation for retraction.

FIG. 8 is a partial longitudinal sectional view showing the flame holder in retracted position.

FIG. 9 is a transverse sectional view taken substantially through a plane indicated by section line 9 -9 in FIG. 5.

FIG. 10 is an enlarged partial sectional view taken substantially through a plane indicated by section line 1010 in FIG. 2.

FIG. 11 is an enlarged partial sectional view taken sub-- stantially through a plane indicated by section line 11-11 in FIG. 10.

FIG. 12 is a partial longitudinal sectional View showing the intake portion of the engine.

FIG. 13 is a front elevational view of the intake portion of the engine.

FIG. 14 is a transverse sectional view taken srbstantially through a plane indicated by section line 14---14 in FIG. 12.

FIG. 15 is a transverse sectional view similar to that of FIG. 4 showing another form of check valve assembly in a partially retracted condition.

FIG. 16 is a partial sectional view taken substantially through a plane indicated by section line 1616 in FIG. 15.

Referring now to the drawings in detail, FIG. 1 illustrates one example of a combined jet reaction engine constructed in accordance with the present invention and generally referred to by reference numeral 10. The engine includes a generally tubular housing 12 extending from an air inlet end 14 to an outwardly flaring tail end section 16 from which thrust producing gases are discharged. Airfoil shaped projections 18 and 20 extend laterally from and intermediate the ends of the housing. Another pair of projections 22 and 24 extend laterally from the housing perpendicular to and spaced forwardly of the projections 18 and 20. The laterally extending projections enclose component receiving cavities as will be explained hereafter.

Referring now to FIG. 2, the jet engine 10 is shown conditioned for pulse jet operation. The housing 12 is internally formed with an annular intake passage section 26 formed about a center body 28 coaxially positioned within the housing by supporting struts 30. The passage section 26 conducts the inflow of air to a check valve assembly 28 associated with pulse jet operation. The constructional details of check valve assembly itself are well known and form no part of the present invention. However, in accordance with the present invention, the check valve assembly 28 is operatively positioned coaxially within the housing and is displaceable from this operative position as will be hereafter explained. Further, the check valve assembly 28 is operatively positioned within the flow passage at a location forwardly of a flame holder 30 which is operatively positioned as shown in FIG. for ram jet operation.

With continued reference to FIG. 2, the flow passage extending rearwardly from the location of the flame holder 30 is enclosed by a housing section 32 of relatively constant diameter and of a preselected length terminated by the outwardly flaring tail end section 16. A nozzle throat member 34 is adjustably positioned within the housing section 32 between a forward, pulse jet position as shown in FIG. 2 and a rearward ram jet position as shown in FIG. 5.

The check valve assembly 28 is positioned by means of a telescoping type of power operated piston device 36. Thus, the check valve assembly may be retracted by the piston device into a receiving cavity 38 formed in the projection 22 for this purpose as shown in FIG. 5. In one embodiment of the invention, before the valve assembly is retracted into its cavity, it is angularly rotated by 90 degrees to a position as shown in FIG. 4. Toward this end, one of the extensible piston rods 40 associated with the piston device 36, has a sector gear 42 connected thereto as more clearly seen in FIGS. and 11 for meshing engagement with apinion gear 44 driven by a motor 46. Thus, the check valve assembly 28 may be angularly oriented for retraction into its cavity 38 or angularly displaced to an operative position after it is extended by the piston device 36 into the flow passage.

FIGS. and 16 illustrate an alternative arrangement for retracting and operatively positioning a check valve assembly constructed in two separable half sections 28' so that each half section may be retracted into cavities 38' dsposed in both of the projections 22 and 24. Power operated piston devices 36' are accordingly mounted within each projection 22 and 24 and connected to the valve assembly half sections 28'. Angularly orientating means will of course also be associated with the piston devices 36 as described in connection with FIGS. 2, 10 and 11.

A retracting mecahnism 48 similar in construction and operation to the retracting mechanism for the check valve assembly hereinbefore described, may be associated with the flame holder 30 for positioning thereof between an operative position as shown in FIG. 5 and an inoperative position as shown in FIG. 8. Accordingly, in one embodiment of the invention, the lateral projection is provided with a receiving cavity 50 into which the flame holder is displaced after it is angularly orientated from its operative position as shown in FIG. 5 to the inter mediate position as shown in FIG. 7.

The nozzle throat member 34 is designed to form a throat restriction within the flow passage of the housing 12. The location of this nozzle throat member will change the internal geometry of the flow passage so as to accommodate either pulse jet or ram jet operation. A positioning mechanism generally referred to by reference numeral 52 is therefore operatively connected to the throat member 34 and is enclosed within a longitudinal projection 54 on the housing. One form of positioning mechanism as illustrated in FIGS. 2 and 5, includes an elongated, externally threaded actuating shaft 56 rotatably mounted within the enclosing projection 54 and threadedly extending through a nut element 58 connected to the throat member 34. The nut element extends through a guide slot 60 formed in the housing section 32 so as to axially move the throat member between its two operative positions upon rotation of the actuating shaft 56 by a motor 62. The throat member as will be explained hereafter, limits the rearward end of the combustion zone in either of its operative positions.

In order to control the inflow rate of air so as to accommodate both pulse jet and ram jet operation, the center body 28 within the intake passage section 26, mounts an axially shiftable nose element 64 having radially extending guide fins 66 slidably received in guide slots 68 formed in the center body as more clearly seen in FIG. 14. The nose element may be provided with a rearwardly extending piston portion 70 slidably received within a pressure controlled chamber 72 through which the nose element may be extended forwardly or retracted rearwardly. The guide fins 66 are operative to axially displace a forwardly converging, truncated conical element 74.

When the nose element 64 is fully retracted, as shown in FIG. 2, the conical element 74 will be resting on the forward conical portion of the center body 28 while the guide fins 66 will be fully retracted within the center body so as to admit a maximum quantity of air into the inlet end of the housing. The flow area of the inlet end 14 when opened by a maximum amount will be dimensioned to conduct the requisite quantity of air into the engine for pulse jet operation. When the engine is converted to ram jet operation at subsonic speeds above 400 m.p.h., the nose element 64 is extended to an intremediate position as shown in FIG. 12 so that the guide fins 26 forwardly displace the conical element 74 to thereby reduce the inlet opening at the forward inlet end 14. In the supersonic speed range, the nose element 64 is fully extended to the position shown in FIGS. 5 and 6 wherein the conical element 74 engages the rim of the inlet opening so that the inflow of air is restricted to the smaller opening at the inlet end of the conical element 74, as more clearly shown in FIG. 13.

Referring now to FIG. 2 in connection with pulse et operation of the engine, it will be apparent that with the inlet end 14 fully opened, the inflow rate of air will be sufiicient to obtain a proper fuel-air mixture within the combustion zone located between the check valve assembly 28 and the throat member 34. Fuel is injected through a fuel injector 76. Following initial air intake, the fuel-air mixture within the com-bustion zone is ignited by the spark plug device 78. As is well known in connection with pulse jet engines, when combustion occurs within the combustion zone, the check valve assembly 28 is closed so that gases resulting from combustion are propelled rearwardly from the combustion zone through the housing section 32 and exit through the tail end section 16 to impart thrust to the engine. As is also well known in connection with pulse jet operation, gases continue to exhaust from the tail end section of the engine because of momentum after the pressure generated by combustion within the combustion zone has returned to atmospheric value. When the pressure within the combustion zone drops to a low point below atmospheric value, the check valve assembly 28 permits reentry of air through the inlet end 14 while air also enters the tail end section of the engine to increase the air mass within the combustion zone. Re-ignition of the new fuel-air mixture within the combustion zone occurs because of residual hot gases to begin a new cycle. Thus, periodic combustion occurs at a predetermined frequency to generate a pulsating thrust. The length of the housing section 32 is therefore selected in order to obtain resonance with the pulsating combustion frequency. Further, in View of the re-entry of air through the tail end section 16, during each pulse cycle, the tail end section must flare outwardly as shown.

It will be appreciated by those skilled in the art, that a pulse jet engine is economical and eflicient at reatively low speeds and will therefore be suitable in accordance with the present invention to start and accelerate any vehicle being propelled by the engine up to a speed of 400 mph. beyond which the efliciency of pulse jet operation drops sharply. Since a pulse jet engine becomes inoperative at 500 mph and above, in accordance with the present invention the engine is converted from pulse jet operation to ram jet operation at about 400 mph. This is accomplished by retracting the valve assembly 28 from the single flow passage of the engine and operatively positioning the flame holder 30 within the flow passage as shown in FIG. 5 together with movement of the exit throat member 34 to its rearward position thereby converting the tail end section 16 to an exit nozzle. Also, in view of the high speed of operation, the inlet opening is reduced by forward displacement of the conical element 74. Further, since pulse jet operation of the engine is only utilized below cruising speeds, the less frequent use of the valve assembly 28 will prolong its life in view of its protective enclosure within cavity 38.

The geometry of the inlet end of the engine is changed for ram jet operation as aforementioned in order to match the inlet flow area to the exit nozzle flow area so that outflow equals inflow to avoid pile up at the entrance to the diffuser passage section 26. The throat member 34 may therefore be dimensioned to provide the proper exit nozzle geometry for ram jet operation not inconsistent with pulse jet operation when the throat member is in its forward position as shown in FIG. 2. Thus, as in the case of most ram jet engines, as the air enters the inlet end of the engine, it increases in pressure most rapidly as its velocity decreases and its temperature increases. Within the diffuser flow section 26, the air increases in pressure and temperature at a lower rate as its velocity continues to decrease thereby maintaining a constant total energy as the kinetic energy is transformed to pressure energy. Prior to entering the combustion zone, the forward end of which is limited by the flame holder 30, the air is mixed with fuel injected through another fuel injector 80 spaced forwardly of the fuel injector 76 utilized for pulse jet operation. Ignition of the fuel-air mixture within the combustion zone may be started by the spark plug 82, the combustion zone extending from the flame holder 30 to the throat member 34- forming part of the exit nozzle. The heat energy added to the fluid within the combustion zone due to combustion, causes a sharp rise in temperature thereof and an increase in velocity while its pressure decreases from a maximum value as the air enters the combustion zone. The flow of gases then undergoes a sharp rise in velocity as it is discharged through the exit nozzle accompanied by a reduction in pressure and temperature, as in the case of most ram jet engines.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. In a combined pulse-jet and ram-jet engine, a tubular housing having inlet and outlet end portions between which a single flow path is established, internal throat means mounted by the housing for dimensionally limiting a combustion zone upstream thereof within said flow path, and positioning means connected to the throat means for displacement thereof between a pulse-jet position spaced upstream of the outlet end portion and a ram-jet position at the outlet end portion of the housing within said flow path.

2. The combination of claim 1 including variable geometry intake means mounted in the inlet portion of the housing upstream of the combustion zone within said flow path for varying the inflow area of the inlet portion to accommodate both pulse-jet and ram-jet operation.

3. The combination of claim 2 including a flame holder device for dimensionally limiting the combustion zone downstream thereof during ram-jet operation, and means mounted by the housing for retracting the flame holder device from the flow path during pulse-jet operation.

4. The combination of claim 3 including check valve means for intermittently blocking inflow to the combustion zone during pulse-jet operation and means mounted by the housing for retracting the check valve means from the flow path during ram-jet operation.

5. The combination of claim 4 wherein each of said retracting means includes a power operated positioning member movable transversely of said flow path, a projection mounted on the housing having a receiving cavity extending laterally from the flow path, and cavity aligning means for angularly displacing the positioning member.

6. The combination of claim 2 including check valve means for intermittently blocking inflow to the combustion zone during pulse-jet operation and means mounted by the housing for retracting the check valve means from the flow path during ram-jet operation.

7. The combination of claim 1 including check valve means for intermittently blocking inflow to the combustion zone during pulse-jet operation and means mounted by the housing for retracting the check valve means from the flow path during ram-jet operation.

8. The combination of claim 7 wherein said retracting means includes a power operated positioning member connected to the check valve means, a projection mounted on the housing having a cavity receiving the check valve means in a retracted position laterally of the flow path, and valve orientating means connected to the positioning member for angularly aligning the check valve means with the cavity to enter the same when displaced to the retracted position by the positioning member.

9. In a combined pulse-jet and ram-jet engine, a tubular housing having inlet and outlet end portions between which a single flow path is established, means mounted by the housing for dimensionally limiting a combustion zone upstream thereof within said flow path, check valve means for intermittently blocking inflow through the flow path to the combustion zone during pulse-jet operation and means mounted by the housing for retracting the check valve means transversely from the flow path without dimensional change thereof to a retracted position for ramjet operation.

10. The combination of claim 9 wherein said retracting means includes a power operated positioning member connected to the check valve means, a projection mounted on the housing having a cavity receiving the check valve means in said retracted position laterally of the flow path, and valve orientating means connected to the positioning member for angularly aligning the check valve means with the cavity to enter the same when displaced to the retracted position by the positioning member.

References Cited UNITED STATES PATENTS 2,677,232 5/ 1954 Collins 60-244 2,683,961 7/1954 Britton 60244 2,745,248 5/ 1956 Winter 60--24@l- 2,850,872 9/1958 Stockbarger 60244 3,078,660 2/1963 Hansel 60-39.77

DOUGLAS HART, Primary Examiner U.S. C1.X.R.

Images