US3040519A - Jet propulsion unit with cooling means for incoming air - Google Patents

Description

June 26, 1962 R. s. RAE 3,040,519

JET PROPULSION UNIT WITH 000mm; MEANS FOR INCOMING AIR Filed Aug. 15, 1954 2 Sheets-Sheet 1 FAA/001. PH J4MUL RAE,

IN V EN TOR.

June 26, 1962 R. s. RAE 3, 4

JET PROPULSION UNIT WITH COOLING MEANS FOR INCOMING AIR Filed Aug. 15, 1954 2 Sheets-Sheet 2 FAA/paw, J/l/w/zz /?,4,

INVENTOR.

ArroxP/vzy aircraft.

The Garrett Corporation, Los Angeles, 'Caiifl, a corporation of California Filed Aug. 13, 1954, Ser. No. 449,704 10 Claims. (Cl. 6tl--35.6)

This invention relates to a propulsion unit having means for cooling the air entering the unit and relatees more particularly to a propulsion unit in which a compressor is utilized to increase the pressure of the cooled air so that the unit can produce a jet reaction force.

Non-air breathing engines, such as disclosed in pending US. Patent Application Serial No. 417,867 filed March 22, 1954 by Randolph Samuel Rae, can be utilized to develop power independently of the surrounding atmosphere so that the engine can be used to propel a craft, such as an aircraft, in mediums where practically no air is available. As illustrated in US. Patent Application Serial No. 417,828 filed March 22, 1954 by Randolph Samuel Rae, such an engine can propel an aircraft by driving acompressor to produce a jet stream through a duct in which the engine is located. However, at high altitudes where the density of the air is low, it is necessary to expend a considerable amount of work on the atmosphere by the compressor in order to compress a sufficiently large amount of air in order to propel the It is therefore proposed by the present invention to cool the air entering the propulsion unit so that for a given compressor discharge pressure, the engine will have to do less work on the air entering the unit. This initial cooling can be accomplished by cooling means positioned in the entrance to the duct and the cooling means can be supplied with the low temperature fuel supply for the engine.

It is therefore an object of the present invention to provide a propulsion unit for propelling an aircraft, which unit is the form of a duct containing a compressor and a cooling unit located ahead of the compressor to cool the air entering the compressor.

Another object of the invention is to provide a propulsion unit in which the air leaves the propulsion unit in a jet stream and in which the air entering the propulsion unit is cooled by a low temperature fluid supply in order to reduce the work on the compressor for a given mass flow of air.

Another object of the invention is to provide a propulsion unit driven by a non-air breathing engine operated on low temperature fuel and oxidant and in which th low temperature fuel is utilized to cool the air entering the propulsion unit. 7

These and other objects of the invention not specifically set forth above will become readily apparent from the accompanying description and drawings in which;

FIGURE 1 is a diagrammatic view of the propulsion unit illustrating the construction of one form of non-air breathing engine that can be utilized with the invention.

FIGURE 2 is a physical form of the propulsion unit showing the cooling unit located ahead of the compressor which is driven by the non-air breathing engine.

FIGURE 3 is a vertical section along line 3-3 of FIG- URE 2 illustrating the construction of the cooling unit located ahead of the compressor.

FIGURE 4 is a view similar to FIGURE 3, partly in section and with portions cut away to show the mounting for the engine and the construction of the cooling coils.

One form of non-air breathing engine which can be utilized in connection with the invention is illustrated in FIGURE 1 and has a storage tank 5 for the engine fuel,

atent 'ice which fuel can be in the form of a low temperature liquid or gas. The fuel tank 5 is connected to'the cooling unit 6 through passage 7 and pump 8 and the discharge from the cooling unit is connected to the outer chamber 9 of heat exchanger unit 10 through passage 11. Chamber 9 is also connected to a first combustion chamber 12 through a passage 13 in order to supply fuel to the combustion chamber. The oxidant for the fuel is stored in a tank 14 which is connected to the outer chamber 15 of heat exchanger 16 through a passage 17 and a pump 18, and the discharge from outer chamber 15 connects with the passage 19. A passage 20 connects passage 19 to combustion chamber 12 and passage 20 contains a valve 21 for controlling the amount of oxidant supplied to the combustion chamber to combust a portion of the fuel. The portion of the fuel in passage 13' which is combusted in chamber 12 determines the temperature in passage 22 which connects the first stage 23 of the engine with the chamber 12. Stage 23 exhausts to a second combustion chamber 24 througha' passage 25 and this second combustion chamber is likewise connected to passage 19 through a passage 26 containing a valve 27 in order to regulate the amount of oxidant directed to combustion chamber 24. In combustion chamber 24, a further amount of fuel will be combusted and this chamber connects with a secondstage 28 through a passage 29. The exhaust from the second stage 28 connects with the third combustion chamber.30 through passage 31 and this combustion chamber is also connected with passage 19 through a passage 32 containing the valve 33. The combustion chamber '30 connects with a third stage 34 through passage 35 and stage 34 exhausts to passage 36 which passage leads through the central chambers 37 and 38 of heat exchangers 16 and 10, respectively, and to afterburner 39 of the engine which will presently be described.

As indicated diagrammatically in FIGURE 1, the output shafts of all the stages are shown connected to a common shaft 40 and it is understood that additional stages can be added to the engine as indicated by the dotted passage extensions in FIGURE 1. While the stages have been illustrated as turbines, other types of gas expansion engines can be utilized for any one or more of the stages. The amount of fuel combusted in each of the combustion chambers 12, 24 and 30 will depend upon the setting of the valves 21, 27 and 33, respectively, and suihcient fuel will be combusted in each combustion chamber to raise the inlet temperature to its-corresponding stage to approximately the maximum which can be withstood by the construction'rnaterials of each stage. Any suitable type of liquid or gas can be utilized as fuel by the engine, such as liquid hydrogen, gasoline, methane, acetylene, alcohol and the like, and the fuel can be combusted with any suitable oxidant, such as air, oxygen, hydrogen peroxide, nitric acid, etc. in either the liquid or gaseous phase. When liquid hydrogen is utilized as the fuel supply and liquid oxygen as the oxidant, heat exchangers 10 and 16 serve to increase the temperature of the hydrogen and oxygen in order to increase the chiciency of the cycle.

The common output shaft 44? is connected to a cornpressor 41 and both compressor 41 and the afterburner 39 are located within duct 42 of the propulsion unit. Upon rotation of the compressor by the engine, the pressure of the air entering the duct will be greatly increased and the exit of this high pressure air from the exit nozzle end 43 of the duct will result in a jet reaction force upon the duct itself. Since passage 36 contains some fuel which is not combusted in the combustion chambers, this fuel can be combusted in the afterburner with a portion of air flowing thr-ough the duct in order to provide added thrust from the propulsion unit.

A physical form of the propulsion unit is illustrated in FIGURES 2 through 4 wherein like reference numerals represent like parts as in the previous description. The engine is contained in body member 44 which is centrally located with the duct 42 by means of four struts 45. Fuel passage 7 supplies fuel to the cooling unit 6 and to passage 11 which passes through one of the struts 45 to heat exchanger 10. Passage 13 connects heat exchanger with the combustion chamber 12 for the first stage 23 of the engine. The combustion chamber 12 is connected by passage 22 with the manifold 46 for the first stage 23 and the manifold 46 has two inlet passages 47. Passage 29 connects combustion chamber 24 with inlet manifold 48 having four inlet passages 49 for the second stage 28 and passage connects combustion chamber 30 to an inlet manifold 50 having eight inlet passages 51 for the third stage 34. The exhaust from stage 34 is passed through heat exchangers 10 and 16 to the afterburner 39. Oxidant is supplied by passage 17 through one of the struts 45 to the heat exchanger unit 16 and then to passage 19 which supplies the combustion chambers. The combustion chambers can be of any well-known construction and can contain a screen having finely divided platinum particles thereon so that when the oxidant is directed against the platinum through a nozzle, the platinum acts as a catalyst to maintain the flame.

The operation of the physical embodiment of the engine is the same as described previously for the diagrammatic form of the invention and the valves 21, 27 and 33 serve to regulate the oxidant supplied to each combustion chamber so as to regulate the amount of fuel combusted in each combustion chamber. Each stage of the physical form is illustrated as a helical flow turbine of well known construction and it is understood that the turbines are all connected to a common drive shaft as illustrated in FIGURE 4. Because of the increased number of inlet passages to each succeeding stage of the engine, it is apparent that the expanded exhaust volume from each turbine can be handled by the succeeding turbine. Each of the helical flow turbines can be supported by brackets 81 positioned on opposite sides of the turbine and secured to body member 44 so that the turbines are held rigidly in position within the body.

The common shaft 40 connects with a substantially conical nose section 57 which has support webs 58 and a central member 59 for receiving the end of shaft Section 57 carries a circular hub member 66 to which are secured two rows of axial flow compressor blades 61 and 62 and two rows of stationary blades 63 and 64 are supported by circular hubmember 65 which is secured to the duct 42. The row of stationary blades 63 is positioned between blades 61 and 62 while the row of stationary blades 64 is positioned aft of blades 62. Since the blades 61 and 62 are rotated at high speed by the non-air breathing engine, the air entering the entrance 66 of duct 42 is compressed to a high pressure and when this high pressure air expands through the nozzle end 43 of the duct, the duct receives a reaction force serving to propel the aircraft on which the duct is mounted. The axial flow compressor, comprised of the movable blades 61 and 62 and the stationary blades 63 and 64, can he of any well known design and additional rows of blades can be utilized if desired. The base portion of nose section 57 covers the forward end of the body member 44 so that the section 57 and the body member 44 form a continuous, streamlined surface within the interior of the duct.

Since the passage 36 connected with the last stage 34 of the turbine contains a portion of the fuel, it is possible to ignite the remaining fuel in the afterburner 39 with the high pressure air in duct 42 and thus increase the temperature of the air leaving nozzle 43. A circular V-shaped ring 52 is positioned between duct 42 and body member 44 and is supported by struts 53. Four cone members 54 are located at the intersection of ring 52 with the struts 53 and a flame holder 55 is supported across the open end of each of the members 54. The flame holders 55 carry a deposit of finely divided platinum which serves as a catalyst to maintain the burning of the fuel within the duct 42. The exhaust passage 36 is connected to a plurality of tubes 56 which terminate at each of the cone members 54 in order to supply the remaining fuel to the catalyst so that it can be ignited with high pressure air being driven through passage 42 and thus raise the temperature of this air and increase the thrust caused by the expansion of the air out of the nozzle end 43.

Referring now to the construction of cooling unit 6 which serves to cool the air entering the duct 43 and compressor 41, a circular member 67 is positioned between the body of duct 42 and its entrance portion 66 and supports the entrance portion by bolts 67'. The member 67 carries a number of cooling fins 63 which project inwardly towards the nose section 57 and a number of helical cooling tubes 63 pass through these cooling fins and are supported thereby. Member 67 also has an entrance header 70 which connects passage 7 with each of the helical tubes 69 and has a discharge header 71 which receives the fuel discharged from each one of the tubes 69. This discharge header connects with the passage 11 which supplies fuel to the stages of the non-air breathing engine. Thus, it is seen that the low temperature fuel supplied by passage 7 circulates through the cooling coils of unit 6 and thereby cools the air entering the inlet 66 of duct 42. Since the air is cooled before it enters the compressor, it is understood that the compressor will have to do less work on the air to obtain a given discharge pressure and mass flow. In other Words, by utilizing the cooling unit 6 in connection with the compressor, it is possible to use an engine of smaller output to obtain a given discharge pressure and a given propulsion unit output.

When low temperature liquid hydrogen is carried as the fuel by tank 5, the hydrogen supplied by pump 8 to the cooling unit will be at a temperature slightly above liquification temperature of hydrogen because of the work done on the hydrogen by the pump. Since the hydrogen enters at the aft side of the cooling unit and leaves at the forward side of the cooling unit, the hydrogen gas passing the the engine from header 31 will be at about ambient temperature and considerable cooling of the air entering the compressor results. Also, if low temperature liquid oxygen is carried by tank 14, the oxygen instead of the hydrogen could be passed through cooling unit 6 on its way to heat exchanger 16 so that the incoming air would be cooled by the low temperature oxygen. The cooling unit 6 can also be utilized when other low temperature fuels and oxidants are used by the engine.

In operation of the present invention, it is understood that the engine comprised of stages 23, 28, 34 drive the common shaft 40 which, in turn, will rotate the blades 61 and 62 of the compressor in order to develop a high pressure within the duct 42 and that the air entering the compressor will be cooled by the cooling unit 6 so that the work load on the compressor for a given discharge pressure will be reduced. The air compressed by the axial flow compressor will be raised in temperature by the combustion of the fuel in the exhaust from the last stage 34 of the engine. Thus, a high temperature, high pressure jet will exist at the nozzle end 43 of the duct 42, which jet can be, utilized for propelling the craft which mounts the propulsion unit.

By the present invention, a propulsion unit is provided in which a compressor and an engine are mounted within a duct to produce a jet thrust. The type of engine described can be very small and compact when low temperature liquid hydrogen and oxygen are used as the fuel and oxidant, respectively. A portion of the hydrogen fuel is utilized as a diluent or working fluid of high specific heat for the engine and this portion is available for the afterburne'r. Various other types of non-air breathing engines can be utilized in connection with the invention and these engines can utilize various substances as fuel and oxidant. Also, other construction of cooling units can be positioned ahead of. the compressor. Various other modifications are contemplated by those skilled in the art without departing from the spirit and scope of the invention as herein defined by the appended claims.

What is claimed is:

' 1. A propulsion unit for producing a jet reaction force for an aircraft comprising a passage means having a nozzle at the exit end, power means positioned within said passage means :andutilizing a low temperature substance as fuel and a low temperature substance as an oxidant, the temperature ofsaid substances being below the temperature of atmospheric air entering said passage means,

compressor means located within said passage means and connected to said power means for increasing the pressure of the air entering said passage means, and cooling means located within said passage means forwardly of said compressormeans for cooling all the air entering said passage means, and means for conducting one of said low temperature substances through said cooling means onits way to said power means, said power means being operative solely'by said'low temperature fuel and oxidant and independently'of the air entering said passage means. I

2. A propulsion unit for propelling an aircraft by creating a jet thrust, comprising a duct having a nozzle exit, an engine supported within said duct by struts and operable independently of the medium surrounding the aircraft, a supply of low temperature hydrogen as the fuel for the engine and a supply of low temperature oxygen as the oxidant for the engine, a compressor located within the duct and connected to said engine in order to compress the air entering the inlet to said duct, cooling means located forwardly of said compressor for cooling all the incoming air prior to being compressed, and means for connecting said cooling means to said engine and to one of said supplies so that hefore entering said engine said one supply provides a cooling medium for the incoming air.

3. A propulsion unit as defined in claim 2 wherein said cooling means is connected to said hydrogen supply and said cooling means discharges hydrogen gas to said englue.

4. A jet propulsion unit comprising passage means having an inlet for atmospheric air at one end and an exit nozzle at the opposite end, compressor means located within said passage means for compressing atmospheric air entering said passage means and discharging said air through said exit nozzle, power means for driving said compressor means, a supply of a low temperature substance for use as fuel for said power means and a supply of low temperature substance for use as the sole-oxidant for fuel supplied to said power means, the temperature of said substances being below the temperature of atmospheric air entering said passage means, heat exchanger means located in said passage means forwardly of said compressor means, means for introducing one of said low temperature substances to said heat exchanger means to cool all the atmospheric air entering said inlet and to increase the temperature of said one substance, means for discharging said one substance from said heat exchanger means to said power means, means for connecting the other of said substances to said power means, said power means comprising combusting means for com busting only a portion of the fuel supplied to said power means with a regulated amount of said oxidant to providea fuel-rich exhaust, and burner means located within said passage means aft of said compressor means and connected only with said exhaust for combusting the fuel remaining in said exhaust with the atmospheric air discharged from.

said compressor means.

5. A jet propulsion unit comprising passage means having an inlet for atmospheric air at one end and an exit nozzle at the opposite end, compressor means located within said passage means for compressing atmospheric air entering said passage means and discharging said air through said exit nozzle, power means for driving said compressor means, a supply of low temperature fuel for said power means and a supply of oxidant for the fuel supplied to said power means, the temperature of said fuel being below the temperature of atmospheric air entering said passage means, heat exchanger means located in said passage means forwardly of said compressor means for cooling all the incoming air, means for introducing said low temperature fuel to said heat exchanger means tocool the atmospheric. air entering said inlet, means for discharging said fuel from said heat exchanger means to said power means, means for connecting said oxidant to saidpower means, said power means comprising a plurality of expansion stages and combusting means for combusting only a portion of the fuel supplied to said power means with a regulated amount of said oxidant to provide a fuel-rich exhaust,,and burner means located within said passage means aft of said compressor means and connected. with said exhaust as the only source of fuel,

said burner means combusting the fuel remaining in said exhaust with the atmospheric air discharged from said compressor.

6. A jet propulsion unit comprising passage means having an inlet for atmospheric air at one end and an exit nozzle at the opposite end, compressor means located within said passage means for compressing atmospheric air entering said passage means and discharging said air through said exit nozzle, power means for driving said compressor means, a supply of low temperature liquid hydrogen for use as fuel by said power means and a supply of oxidant for said power means, heat exchanger means located in said passage means forwardly of said compressor means, means for connecting said hydrogen supply with said heat exchanger means to cool the atmospheric air entering said inlet and to increase the temperature of said hydrogen, means for discharging saidhydrogen from said heat exchanger means to said power means, means for connecting said oxidant to said power means, said power means comprising combusting means for combusting only a portion of the hydrogen supplied to said power means with a regulated amount of said oxidant to provide a hydrogen rich exhaust, and burner means located within said passage means aft of said compressor means and connected with said exhaust as the only source of fuel, said burner means combusting the hydrogen in said exhaust with the atmospheric air discharged from said compressor.

7. A jet propulsion unit as defined in claim 6 wherein said power means includes a plurality of expansion stages, each of said stages receiving uncomhusted hydrogen as a working fluid of high specific heat, said combusting means increasing the entering temperature to each stage to a maximum temperature that can be withstood by each stage.

8. A jet propulsion unit comprising means forming a duct having an air inlet at one end and a reduced jet nozzle at the opposite end; a body supported in said duct forming means and co-operating therewith to give the duct an annular configuration between said inlet and said nozzle; an engine in said body; compressor rotor means in the annular section of said duct adjacent the forward portion thereof, said compressor rotor means being connected for operation by said engine to compress air entering said inlet and direct it around said body and outwardly through said nozzle; heat exchanger means in said duct between the inlet end thereof and said compressor rotor means for cooling all the air directed around said body by said compressor rotor means, said heat exchanger means having a fluid passage; a supply of fuel for said engine at a temperature lower than the temperature of air entering said inlet, and means for conducting said fuel to said fluid passage and from the latter to said engine.

9. A jet propulsion unit comprising inner and outer body means forming a duct having an inlet at one end, a jet nozzle at the other end and an annular intermediate portion progressingly decreasing in cross-sectional area toward the nozzle end; engine means wholly enclosed in said inner body means; a compressor rotor adjacent the forward end of said annular intermediate portion, said compressor rotor being driven by said engine to draw air into said inlet and direct it through said annular intermediate portion to said nozzle; first and second heat exchangers each having a pair of fluid passages, the first of said heat exchangers being disposed in said duct in advance of said compressor rotor to cause air drawn into said inlet to flow through one of the fluid passages in said first heat exchanger; means for directing fuel through the other fluid passage in said first heat exchanger and through one fluid passage in the second heat exchanger to said engine means; means for directing exhaust gases from said engine means through the second fluid passage of said second heat exchanger; and burner means in the annular intermediate portion of said duct immediately in advance of said nozzle, said burner means receiving the exhaust gases following passage thereof through said second heat exchanger.

10. A jet propulsion unit comprising means forming a duct'having an inlet at one end and a reduced jet nozzle at the other end; body means supported in said duct and serving to give the same an annular configuration between said inlet and said nozzle; engine means in said body means and operable to have a fuel-rich exhaust; compres-' sor rotor means in the annular section of said duct adjacent the forward portion thereof, said compressor rotor means being connected for operation by said engine means to draw air into said inlet and direct it around said body means and outwardly through said nozzle; heat exchanger means surrounding said body means between said compressor rotor means and said inlet for cooling all the air directed around said body means, said heat exchanger means having a fluid passage; fuel conducting means leading from a low temperature source of fuel to the fluid passage in said heat exchanger means and from the latter to said engine means; annular burner means supported in the annular section of said duct adjacent the nozzle end thereof; and means for conducting the exhaust from said engine means to said burner means in order to combust the fuel in said exhaust with the air directed around said body means.

References Cited in the file of this patent UNITED STATES PATENTS 664,958 Linde Jan. 1, 1901 2,339,185 Nettel Ian. 11, 1944 2,408,111 Truax et a1. Sept. 24, 1946 2,455,845 Wells Dec. 7, 1948 2,511,385 Udale Jan. 13, 1950 2,563,744 Price Aug. 7, 1951 2,563,745 Price Aug. 7, 1951 2,575,683 Price Nov. 20, 1951 2,602,289 Anxionnaz et a1. July 8, 1952 2,688,843 Pitt Sept. 14, 1954 2,693,674 Anxionnaz et a1 Nov. 9, 1954 2,754,655 Holzwarth July 17, 1956

Images