US2628471A

US2628471A - Synchronous augmenter for resojet motors

Info

Publication number: US2628471A
Application number: US608542A
Authority: US
Inventors: James Y Dunbar
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-08-02
Filing date: 1945-08-02
Publication date: 1953-02-17
Anticipated expiration: 1970-02-17

Description

Feb. 17, 1953 J. Y. DUNBAR SYNCHRONOUS AUGMENTER FOR RESOJET MOTORS Filed Aug. 2. 1945 'INVENTOR JAMES Y DU NBAR ATTORNEY Patented Feb. 17, 1953 SYNCHRJONOUS AUGMENTER FOR RESOJET MOTORS James Y. Dunbar, United State Navy Application August 2, 1945, Serial No. 608,542

8 Claims.

(Granted under This invention relates to an auxiliary synchronous augmenter for jet propulsion devices such as operate cyclically or in resonance.

An object of this invention is toprovide an augmenter that increases the compression and consequently the efficiency of jet propulsion de: vices operating cyclically or in resonance.

A further object of this invention is to provide a device whereby the exhaust of one motor operating cyclically or in resonance augments the compression of another similar operating motor.

Other objects and advantages of this invention will become apparent as the discussion proceeds and is considered in connection with the accompanying claims and drawing wherein like characters of reference designate like parts in the several views and wherein:

Fig. I is a schematic view of a reso-jet motor showing the augmenter embodied in this invention;

Fig. 11 is a longitudinal section view of a resojet motor showing one modification of the augmenter embodied in this invention;

Fig. III is a schematic view of another modification of the augmenter embodied in this invention.

Referring now to the drawing, wherein for the purpose of illustration, are shown preferred'embodiments of this invention, the numeral 4 designates the tail pipe or resonant exhaust tube of a conventional reso-jet motor. The numeral 5 designates an explosion chamber communicating with the said tail pipe, having a spark ignition means 6 such as a. conventional spark plug. The end of the said explosion chamber 5 is provided with an end plate 1, carrying a rotating valve 8 which meters fuel and air or air only into the said chamber 5. In the modification shown in Fig. I the valve 8 is any conventional type of mechanically operated high speed valve such as a rotating valve driven by a synchronous motor I. An auxiliary passage opening or hole 9, disposed toward the end of the tail pipe 4, is adapted to receive a tail pipe ll of a smaller synchronously operated auxiliary reso-jet motor designed for the same operating frequency as the large motor, as shown. The said tail pipe ll carries a combustion chamber 12 provided with a valve l3 driven also by the synchronous motor. A suitable mechanical link-age l4 connects the synchronous valve 13 to the synchronous valve 8 phased approximately 180 degrees therefrom. The phase angle is susceptible to being varied by relative phase adjustment coupling 29 to provide the optimum efficiency and firing times for the two 1 motors.

Title 35, U. S. Code (1952),

sec. 266) In the modification shown in Fig. 11 the tail pipe or resonance tube 4, the combustion chamber 5, the electric combustion firing means 6 and end plate 1 are the same as in Fig. I. Ihe valves I5, afiixed to the plate I, are of the vibrating or reed type. A hole 9 disposed near the end [0 of the tail pipe 4, as in Fig. I, has a tail pipe II, and a much smaller synchronously operated inotor affixed thereto, disposed at an angle, substantially as shown. Afiixed to the tail pip'elll is a combustion chamber [2 carrying electric ignition means it, as shown. Vibrating valves I! of the reed or resilient type are providedin the end of the combustion chamber 12 to admitair or air and fuel.

In the modification of this invention shown in Fig. III the numerals I8 and I9 designate'the tail pipes of two identical reso-jet motors having combustion chambers 20 and 2!, respectively, affixed thereto. Air is admitted to the combustion chambers through valves 23, of any conventional design. Conventional spark plugs or other electric firing means 24 are provided in the combustion chambers 20 and 2| to fire the charges. A U tube 25 disposed in the tail pipes l8 and i9, and in open communication therewith, is affixed to the said tail pipe 18 at 26 and to the said tail pipe R9 at 27. It is to be noted that the U is turned towards the combustion chambers 20 and 2 I. The motors are rigidly afi'ixed together at 28 in any conventional manner, s by welding vor the like.

In operation the auxiliary synchronousaiigmenter as shown in Figs. I and II, consists of a dual resonant jet'motor, the largerunit being the propulsion unit and the maller the compressor unit, each unit augmenting the compression of the other. 1

If the gas in the motor (due to theexplosion in the combustion chamber), is excited into motion, it tends to oscillate at the natural frequency of the unit until brought to rest by damping or friction. If the explosion taking place in the explosion chamber has the ame periodicity as the natural frequency of the motor the motion "of the gas in the tail pipe will build up to a maximum value limited only by friction or damping or by the constant governing the inertance' and compliance of the resonator system. Friction damping may be reduced to a minimum by proper shaping and smoothing the inner surface'of the motor parts. But the inertance and compliance of the system, which determines the natural frequency characteristics, are both functions of gas density which varies during the cycle. Should the gas mass in the tailpipe be considered as a piston N moving outwardly, the maximum restoring force or pressure attainable will be the ambient atmospheric pressure, if a complete vacuum can be created. If the piston moves inwardly, the compression is adiabatic and approaches infinity. *Sh'ould zinexplosive'charge be introduced into the chamber at the end of the outward stroke, the weak restoring force, drawing the piston (or gas) back into the tail pipe,causes very little pre-compression of the fuel mixture. results in loss of both power and elficiency. But if an auxiliary compressor be used to provide a high compression of the charge or mixture, the thrust and efliciency is improved.

When this auxiliary compressor is itself a smaller, similar resonating .jet motor, its fuel mixtur is compressed by 'themain. motor discharge, and the main.motor in turn receives its vcompression from the firing of the auxiliary "motor.

Thus-a concatenation takes place be- "tween' thetwo motors to achieve ahigher overallefiiciency.

I These two motors maybe kept in proper phase relation toeach'other by means of mechanically driven'valvesof any conventional type (specific "titail's'of'which are'not shown here), interconfnected todrive at the same frequency, as illustrated in Fig. I, or when using a motor having *avibrating orree'd typevalve as shown in Fig.

"-"lIythetwomotors are designed so that they have 'ra'ngement of parts may be resorted to, without I departing from the spirit of my invention, or 'the'scope ofth'e subjoined claims.

The invention described herein may be manu- Ff'ac'tured'a'nd used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

"What I claim is:

1. An augmenter 'forreso-j'et motors comprising a plurality of 'r'es'oet motors each "having a combustion chamber with a fluid inlet, an intermittently operable inlet valve upstream of said combustion chamber, a tailpipe having an outlet and in alignment with the combustion chamber, a conduit opening through the wall of the tail .pipe of :one of said -motors downstream of its combustion chamber and having a longitudinal axis disposed at an acute angle and extending .rearwardly-of the tail pipe, said conduit being connected to the tail pipe of another of said motors,'synch-ronizing means for oppositely phas- 'ing said :two motors for mutual alternate augmentation of the compression steps in each of said moto'rs by the discharging gases from exauxiliary passage means "in the wall or at least one exhaust tube through which exhaust gas from the explosion chambers of at least two reso-jet motors is directed into the exhaust tube and toward the explosion chamber of the other, the exhaust tube of at least one of said reso-iet motors being open at one end forescape of exhaust propulsion gas, and synchronizing means for firing the said two reso-jet motors alternately.

3. The combination set forth in claim 2 further defined i'n'that the auxiliary passage means is shaped to reverse the direction of movement of exhaust gas'passing through it.

4. An augmenter for a main reso-jet motor having a combustion chamber, a resonant exhaust tube and a mechanically driven valve communicating with said chamber, comprising a smaller auxiliary reso-jet motor having a combustion chamber and a mechanically driven valve municating with said chamber, comprising a smaller auxiliary reso-jet motor having a combustion chamber and a mechanically driven valve communicating with said chamber, a driving linkage synchronously connecting the first mentioned valve to the said mechanically driven valve, and a resonant exhaust tube afiixed to the exhaust tube of the said main motor, said smaller auxiliary motor being timed to fire out of phase with the main motor.

6. In combination, a plurality of reso-jet motors each having a combustion chamber with a fluid inlet upstream thereof, an igniter and an intermittently operable inlet valve for said combustion chamber, and a tail pipe connected to the combustion chamber, the tail pipe of one of said reso-jet motorsbeing open at one end and-having an opening along its length downstream of-said combustion chamber, said opening forming the entrance of an auxiliary passage to the tail .pipe of a second reso-jet motor, and means for firing the two named motors sequentially so that .part

ofthe exhaust gas from the explosion in the-combustion chamber of the first named motor will move into the tail pipe of the second named motor.

7. In combination, a plurality of l'GSO-rjfit motors leach-having a fluid inlet, 'a combustion chamber, an intermittently operable inlet valve for said combustion chamber, and a tail pipe aligned with the combustion chamber, the tail valves of both named motors to operate in -sequence so that part of the exhaust gas from the explosions in the combustion chamber of 'the said motor having the open tail pipe will move into the tail pipe-of the second motor, and means for firing the second motor after exhaust gas has moved into its tail pipe.

8. In a -j etengine, a first reso-jetmotor having "a combustion chamber, "an air inlet o' mm lupstream of said chamber, a tail pipe in alignment with said combustion chamber to receive and convey products of combustion from said chamber to the atmosphere, and means operatively connected with said chamber for igniting fuel in said chamber, a second reso-jet motor companion to said first reso-iet motor, said second motor including a combustion chamber with a tail pipe connected. therewith and a fluid inlet opening upstream of the last-mentioned chamber, said first-mentioned tail pipe having a lateral opening therein downstream of said first-mentioned combustion chamber, and, said second motor tail pipe being communicated with said lateral opening, said second motor combustion chamber hav-- ing ignition means for said second motor timed to operate during the compression stage of actuation of said first reso-jet motor so that exhaust gas from said second motor passes through said lateral opening and into the first motor tail pipe to augment the compression in said first motor. JAMES Y. DUNBAR.

6 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS