US2530649A - Fuel supply system for continuous combustion turbine type aircraft - Google Patents

Description

Nov. 21, 1950 F. H. CAREY 2,530,649

FUEL SUPPLY SYSTEM FOR CONTINUOUS comaus'rxon TURBINE TYPE AIRCRAFT Filed Jan. 14, 1948 4 Sheets-Sheet l linen rag 67/. Gaefif arw w Nov. 21, 1950 F. H. CAREY 2,530,649 a FUEL SUPPLY SYSTEM FOR CONTINUOUS comausnou TURBINE TYPE AIRCRAFT Filed Jan. 14, 1948 4 Sheets-Sheet 2 Y, a 2 M N M i P WC Yw y H. F 4 Y/ a Nov. 21, 1950 F H CAREY I 2,530,649

FUEL SUPPLY SYSTEM F OR CONTINUOUS COMBUSTION TURBINE TYPE AIRCRAFT Filed Jan. 14, 1948 4 Sheets-Sheet 3 a/YW W Nov. 21, 1950 F. H. CAREY FUEL SUPPLY SYSTEM FOR CONTINUOUS COMBUSTION TURBINE TYPE AIRCRAFT Filed Jan. 14, 1948 4 Sheets-Sheet 4 Patented Nov. 21, 1950 FUEL SUPPL Y SYSTEM: FOR," CONTINUOUS COMBUSTION TURBINE TYPE AIRCRAFT Frederick Henry Carey, Cheltenham, England, assignor to Dowty Equipment Limited, Cheltenham, England Application January 14, 1948, Serial No. 2,341 In Great Britain December 24, 194'? Claims. (Cl. 158-36-4) This invention relates to systems for supplying liquid fuel to the engine of a continuous combustion turbine type power unit, such as is shown in my copending application, Serial No. 2,343, filed January 14, 1948, and is concerned with the problem of leaving the engine burners and combustion chambers dry in order that a fresh starting-up operation can be carried out with safety and without detrimental effects upon the engine. To this end, and in accordance with the invention, such a system comprises pump means which, during a stopping condition of the system; serves as a scavenging pump by having its inlet in communication with the burners and its outlet in communication with the tank. It is convenient to use as the scavenging pump a pump which during starting or running conditions of the engine forms a part of the normal supply system by serving or assisting in the delivery of fuel to the burners. When such a pump is enginedriven it is utilized as a scavenging pump in accordance with the invention by transferring the supply communication with the burners from the outlet to the inlet of the pump and at the same time placing the outlet'of the pump in communication with the tank. In this way flow in the supply line from the pump to the burners is reversed and any fuel which is not consumed at the burner nozzles during the process of stopping the engine and any fuel in the system which is adjacent to the burners will be withdrawn by the pump and passed back towards the fuel tank.

The necessary modifications to the system to efiect changeover from running to stopping can conveniently be made by one or more valves, turn-cocks, or equivalent, operated simultaneously by a hand or other actuator.

By means of the invention, the burners and adjacent portions of the system are automatically drained of fuel thus avoiding the risk of fuel pools forming in the combustion chambers which on starting would cause local and" general overheating of the engine. It is an advantage of the invention therefore that there is no necessity for draining away or dumping unused fuel which hitherto would have succeeded in entering and forming pools in the combustion chambers.

It is not essential that the whole of the system be drained in this way, it being sufllcient and in fact desirable to drain only the burners and the fuel lines in the vicinity of the burners, and to maintain any movable parts of the system, such as pumps and valve elements, in a flooded condition to avoid the risk of corrosion.

The invention is applicable to systems of differing types and some examples will now be described with reference to the accompanying diagrammatic drawings, of which:

Figures 1 and 2 show one system in its normal 7 running and stopping conditions respectively, and

Figures 3 and 4 are similar views of another system.

The system shown in Figures 1 and 2 incorporates simple direct-injection type burners one of which is designated by the reference numeral I. The burners i aresupplied with fuel from a tank 2 by an engine-driven pump 3 which draws the fuel along a conduit 4, through a portion of what may be termed a change-over valve indicated generally at 5, and along an intake conduit 6, and delivers it along the output conduit 1 through a metering valve 8, along the conduit 9, and through another part of the change-over valve 5 to the supply line ill of the burners. When the system is to be converted from its normal running to its stopping condition the movable element of the change-over valve 5 is displaced by the clockwise rocking of a control lever II from the position shown in full lines in Figure 1 to the position shown in full lines in Figure 2. This displaces the movable elementof the valve 5 so that the intake conduit 6 of the pump 3 is cut off from the conduit 4 and is placed in communication with the supply line ID of the burners. Flow in the supply line I0 is therefore reversed, and the pump delivers through the conduit 1 and branch conduit I2 and through a section of the change-over valve 5 to the conduit 4 by way of the branch conduit l3. At the same time the delivery conduit 9 is cut off from the normal supply line ID, at the valve 5, hence the line 9 does not drain. Reversal of the metering valve 8,

normally simultaneously with reversal of the valve 5, further prevent's'drainage of the line 9.

The system shown in Figures 3 and 4 incorporates burners of the known spill type one of which is indlcated at I4, and comprises essentially two pumps of which one, an engine-driven circulating pump l5, operates normally to circulate fuel around a circuit including a supply conduit 16, Ilia, a burner ring l'l, burners ll, of which several would be connected to the burner ring I1, and a collector ring l8 and return conduit I9.

The other pump, an engine-driven supply pump.

20, operates normally to inject fuel into the circulating flow at a point in the return conduit IS. The supply pump 20 withdraws fuel from a tank 2|, the fuel flowing along a conduit 22, through a section of a change-over valve 23 and along an intake conduit 24. The pump delivers the fuel along a conduit 25, through a metering valve or throttle 26, along a conduit 21, through another section of the valve 23 and along a conduit 28 which joins the return conduit l9 running from the collector ring I. to the circulating pump l5. When the system is to be transformed from its normal running condition shown in Figure 3 to its stopping condition shown in Figure 4, a hand lever 29 associated with the movable element of the valve 23 is moved in a clockwise direction away from the full line position of Figure 3 into the full line position of Figure 4. The communications between various conduits is now modifled with the result that a portion of the burner supply line It, indicated at 16a, now communicates through a portion of the valve 23 and through a conduit with the return conduit [9 so that fuel within the burners I4 and within the burner and collector rings l1 and I8 respectively is withdrawn along the return conduit I8 by the pump l5 which now delivers through the conduit l6 and through a section of the changeover valve 23 back to the tank 2| along the conduit 22. The circuit is at the same time modifled so that the supply pump 20 now serves merely to circulate fuel around a circuit including the conduit 25, the change-over valve 23, and the conduit 24. In case the system should be changed to a stopping condition with the metering valve 26 open, the flow along the conduits 21 and 28 by which the fuel normally injects into the circulating flow, is interrupted by the change-over valve 23.

In the examples illustrated, the flow in the supply line from the pump to the burners is reversed and any fuel not consumed at the burners during the stopping process and any fuel adjacent to the burners is withdrawn back towards the tank so that no fuel is allowed to form pools in the combustion chambers of the engine. The invention enables a fresh starting-up operation to be carried out with safety and without detrimental effects upon the engine and avoids the necessity for the "dumping of any fuel.

I claim:

1. A fuel supply system for aircraft engines of the continuous combustion turbine type, comprising a fuel reservoir, a burner nozzle, pump means, a change-over valve casing, a valve in said casing shiftable between a normal operating position and a stopping position, and conduit means interconnecting the pump means with thereservoir and with the burner nozzle, respectively, by way of the valve casing, for supply of fuel during normal operation to the nozzle and return of unused fuel therefrom during stopping, said conduit means including two by-pass passages, one between the nozzle and the intake side of the pump means and the other between the delivery side of the pump means and the reservoir, respectively, and said valve being formed with lands and passages arranged to close off said by-pass passages during normal operation and leave open the normal pump supply and delivery conduits, but to open the by-pass passages and close off the normal pump supply and delivery conduits, for withdrawing from the nozzle during stopping the unused fuel which was theretofore supplied to it during normal operation, and for returning the so-withdrawn fuel to the fuel reservoir.

2. A fuel supply system as in claim 1, characterized in that the burner nozzle is formed for supply of fuel to it and return from it of unused fuel, and further characterized in that the pump means comprises a circulating pump and a leperate supply pump, and wherein the conduit means directly connected to the circulating pump normally affords a closed circulating path which includes the burner nozzle and its supply and return lines but not the reservoir, and the com duit means directly connected to the supply pump draws from the reservoir and feeds into the burner return line to the circulating pump, and further characterized in that the by-pass passages are arranged to provide a closed circulation path for the supply pump during stopping, and to connect th burner nozzle to the intake side of the circulating pump and the latters delivery side to the reservoir.

3. A fuel supply system as in claim 1, characterized in that the burner nozzle is formed for supply of fuel to it and return from it of unused fuel, and further characterized in the inclusion of conduit means to connect the supply and return sides of the nozzle to the intake side of the pump means during stopping, but to connect them respectively to the delivery and the intake sides during normal operation.

4. A fuel system for an aircraft internal combustion turbine engine comprising. in combination with a burner, a fuel tank, and a pump; first conduit means extending from the fuel tank and branched for connection with each of the intake and delivery sides of the pump, second conduit means extending from the burner supply port and likewise branched for connection with each of the intake and delivery sides of the pump; valve means in said first and second conduit means controlling communication between the pump and each of the fuel tank and the burner, and normally positioned to leave open one branch in the'first conduit means for supply from the fuel tank to the intake side of the pump, and to blockthat branch from the fuel tank to the delivery side of the pump, and also to leave open one branch in the second conduit means for supply from the pump to the intake port of the burner, and to block that branch from the intake port of the burner intake port to the intake side of the pump, said valve means being shiftable to a stopping position, wherein to open that branch in the second conduit means which establishes communication between the burners intake port and the intake side of the pump, and to block that branch which formerly established communication between the burner and the delivery side of the pump, and also to open that branch in the first conduit means which establishes communication between the delivery side of the pump and the fuel tank, and to block that branch which formerly established communication between the fuel tank and the intake side of the pump.

5. A fuel supply system for aircraft engines of the continuous combustion turbine type, comprising a fuel reservoir, a burner nozzle, a single pump, a change-over valve casing, a fuel supply line running for normal operation to the pump from the reservoir by way of said valve casing, and having a branch normally blocked off, for alternate return communication from the valve casing back to the reservoir, a fuel delivery line running from normal communication from the pump, by way of the valve casing, to the burner nozzle, and having a branch, normally blocked off, for alternate return communication from the pump to the valve casing and thence by way of theaforesaid alternate branch to the reservoir, and an alternate 5 by-pass, normally blocked oil, from the nozzle by way of the valve casing to the intake side of the pump, and a valve in said valve casin shiftable between a normal operating position, to afford communication between the reservoir and the pump, and thence to the burner nozzle, and a a stopping position, wherein it blanks oil the normal connections between the pump and reservoir and the valve casing, and establishes the alternate connections, for pump-actuated scavenging of the burner nozzle and return of unused fuel therefrom to the reservoir.

FREDERICK HENRY CAREY.

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

UNITED STATES PATENTS Number Name Date 2,334,679 Mason et al Nov. 16, 1943 2,494,778 Plass Jan. 17, 1950 FOREIGN PATENTS Number Country Date 14,234-28 Australia July 4, 1929

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