US2568921A - Combustion chamber with rotating fuel nozzles - Google Patents

Description

Sept. 25, 1951 R. P. KROON COMBUSTION CHAMBER WITH ROTATING FUEL NOZZLES Filed April 27, 1948 2 Sheets-Sheet 1 INVENTOR RE/NQUT R KRoo/v ATTORNEY p 1951 R. P. KROON 2,568,921

COMBUSTION CHAMBER WITH ROTATING FUEL NOZZLES Filed April 27, 1948 2 Sheets-Sheet 2 moms SECTION \w g 5% I 3/- INNER 5cT/ a/v FIG. 6.

WITNESSES: INVENTOR REM/our F. ,KRoo/v ATTORNEY Patented Sept. 25, 195E zsca'szi COMBUSTION CHAMBER WITH ROTATING FUEL NOZZLES Y Reinout l. Kroon, Swarthmore, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Yo a corporation of Pennsylvania Application April 27, 1948, Serial No. 23,539

4 Claims. (01. swam v This invention relates to fuel combustion apparatus and has for an object the provision of improved means for supplying and distributing fuel into the combustion chamber of a gas turbine engine. 1

In a conventional aviation gasturbine engine comprising a cylindrical casing which houses an axial-flow compressor, fuel combustion apparatus, 'a turbine for driving the compressor, and a discharge nozzle, liquid fuel is usually atomized in the combustion chamber by way of a stationary manifold and nozzles. With this type of fuel supply system, a high pressure pump, auxiliary controls and a dump valve device are generally employed as parts of the equipment.

It is proposed to utilize the high rotational speed of the shaft in an engine of the above type, as a means for eflfecting distribution of fuel under pressure in the usual combustion chamber by centrifugal force. thus dispensing with a fuel pump designed to operate against a high pressure. i

The invention; accordingly, has for another object the provision of a rotary ducted impeller element carried on the shaft in operative alignment with the combustion chamber, by means of which fuel can be discharged at high centrifugal pressure into the combustion chamber in atomized form. I

Another object of the invention is the provision of an improved fuel supply apparatus comprising rotary'impeller means operative to effect uniform circumferential distribution of atomized fuel in a manner which will minimize development of hot spots in the combustion apparatus.

A further object of the invention is to provide improved fuel distribution means including a centrifuge carrying fuel nozzles having spray oriflces many times larger than those necessary with stationary fuel nozzles, thus avoiding danger of clogging or stoppage due to contaminated fuel.

A still further object of the invention is the provision of a fuel supply mechanism for a gas turbine power plant of the above typ in which residual fuel remaining in the supply means when the engine is shut down will be negligible, so that the usual dump valve may safety be eliminated.

It is also an object to provide a rotary fuel nozzle device having an arm -of varying air foil section, the outer' and inner sections being adapted to propel the air away in the direction of the fuel spray, and the middle section being shaped to effect movement of gases in the opposite direction or toward the nozzle.-

These and other objects are effected by the invention as will be apparent from the following description .and claims taken in connection with the accompanying drawings, forming a part of this application, which:

Fig. 1 is an elevational schematic view, partly in section, of a gas turbine power plant equipped with fuel supply means constructed in accordance with one form of the invention;

Fig. 2 is a fragmentary sectional view, in enlarged detail, of a portion of the fuel supply means shown in Fig. 1; I

Fig. 3 is a sectional view taken substantially along the line III-III of Fig. 1;

Fig. 4 is a fragmentary sectional view illustrating a portion of a fuel supply apparatus constructed in accordance with a different form of the invention;

Fig. 5 is a fragmentary sectional view taken substantially along the line V-V of Fig. 4;

Fig. 6 is a fragmentary sectional view taken substantially along the line VI--VI of Fig. 4; and

Fig. 7 is a diagrammatic development, in enlarged detail, of rotary blades of the apparatus shown in Figs. 4, 5 and 6.

Referring to Fig. 1 of the drawings, the gas turbine engine therein illustrated in diagrammatic form is one of a type adapted to be equipped with a fuel distributing apparatus embodying the invention, and comprises a streamlined outer casing structure Ii which may be mounted in or on the fuselage of an aircraft and in which the operating elements of the engine are arranged in line to present minimum frontal area and drag during operation of the plane at high speed. Supported within the casing structure ii is an inner casing structure i2. which together.

with the outer casing structure forms an annular passageway i3 constituting a flow communication that extends longitudinally through the engine from a forwardly directed air intake opening it to a rearwardly disposed discharge nozzle i5. Mounted in the casing structure "-42 along the axis thereof are a fairing section it, which may contain auxiliary control apparatus (not shown), a multiple stage axial-flow compressor I'I, fuel combustion apparatus I! including an annular basket structure or shell 20, and a turbine II. The rotor of the compressor I! is adapted to be driven by the turbine 2i through the medium of an axially disposed shaft 22, which may be suitably journaled within the casing structure if.

According to well-known principles of opera tion of gas turbine engines, air enterin the intake opening I4 is compressed by the compressor I! and supplied to the combustion apparatu: "-20 for supporting combustion of fuel thereir while also protecting adjacent surfaces of the power plant from resulting high temperatures Hot motive fluid issuing from the combustion apparatus is then expanded through the turbine 21 and finally discharged through the nomle II in the form of a jet establishing a propulsive thrust.

According to the invention. as best illustrated in Fig. 2, the shaft 22 is adapted to carry a rotary impeller disc or member indicated generally at 25. which comprises a central portion 26 that may be welded or otherwise secured to the shaft. 22. and an outer portion 21, which is adapted to extend through an annular opening 28 formed in the inner casing structure l2 and through an annular lateral entryway 29 formed in the basket structure 20. the impeller member thus extends into the combustion chamber 22a formed within the annular basket structure 20. and is adapted to carry two or more nozzles II, which are preferably disposed substantially midway between the outer and inner walls of the basket structure 22, as shown in Fig. 2; Formed in the central portion 28 of the impeller member is an annular recess 33, which communicates through suitable radially disposed passages 31 with the respective nozzlesjl. It will be understood that the impeller member 25 and associated elements are disposed in operative alignment with the upstream end of the combustion apparatus is, and that the nozzles are pointed downstream, in the form ofthe invention illustrated in Fig. 2.

In order to insure desired radial distribution of fuel spray during high speed operation of the impeller member, 25 and vnozzles 3|, as hereinafter more fully explained, each of the nozzles II is mounted in a suitable inwardly inclined bore formed in the impeller member so that each nozzle is canted inwardly at an angle B with respect to a line parallel to the axis of rotation of the impeller member.

As.,shown in Fig. 3 of the drawings, the impeller member 25 may be provided with a substantially unbroken annular outer portion 21 supported on the central portion 26 by means of radial portions 35, between which are formed annular spaces for enabling air under pressure to flow without appreciable interruption through theannular passage II. If desired, however, the outer portion 21- may be made up of spaced spokes or portions constituting continuations of the radial portions II, without departing from the spirit of the invention.

For supplying liquid fuel to the impeller member 25 there is provided a fuel supply conduit 31, the outer end of -whieh may communicate with a fuel supply system of any desired construction (not shown), and the inner end of which is adapted to project into the annular recess 23 formed in the impeller member 25. It will be understood that the fuel supply system will include means for maintaining a fuel pressure suiiiclent to cause fuel to flow from the conduit 21 into the annular recess 23 during operation of the engine.

In operation, when the shaft 22 has been brought to a predetermined speed by operation of. the usual starting device for which the engine may be equipped, fuel is supplied under relatively low pressure by way of the conduit 21 to the annular recess 32. and is picked up by the impeller member 25 and thrown outwardly through the several ductsor passages 24 and through the respective nonles 3| into the combustion chamber 204. Since the rotational speed of impeller member 28 will be that of the compressor shaft 22, which may be on the order of 12,000 R. P. M., the force with which the fuel is discharged by way of the nozzles 2| will be sufficient to effect atomization of the fuel'into finely divided particles which are then carried with The outer portion 21 ofthe stream of air flowing through the passageway l3 and through the usual apertures in the combustion basket structure 20. It will be understood that suitable means for initially igniting the combustible mixture of fuel and air will be included with the combustion apparatus, although such means are not included in the drawings.

The pressure of fuel issuing through the nozzles 2|, due to centrifugal force acting upon the passages 24 during rotation of the impeller member at normal operating speed. may be expected to obtain a value'many times the fuel pressure available with a conventional fuel system. For example, assuming a shaft speed of 12,000 R. P. M., a nozzle radius of 8 or 9 inches, and a surface radius of the fuel entering thepassages ll of about 3 inches. it can be demonstrated that a fluid pressure in excess'of 3,000'pounds pr square inch will be obtained at the nozzles 2|. Assuming further that four rotating nozzles II are employed and that the quantity of fuel delivered through each nozzle is proportional to the square root of the pressure, the effective flow area of each nozzle may safely be made several times as large as would be necessary in the case of conventional stationary fuel supply equipment employing some three score nozzles and a fuel pump pressure .of about 500 pounds per square inch. It will thus be seen that the relatively large passages of the nozzles II are not likely to clog and vary in efllciency even when supplied with contaminated fuel.

Due to the canted or inclined position of the nozzles 2|, any tendency of fuel leaving the nozzles to continue along a tangential path, or to be thrown outwardly, is counteracted. By orienting each of the nozzles 2i at a predetermined angle B with respect to the engine axis, the net increase in radius of the fuel spray entering the combustion chamber 20a can be controlled or effectively minimized. In practice, air resistance may also considerably change the paths of the fuel particles, and it may accordingly be desirable, for certain classes of service, to provide nozzles located at different radii, with the outermost nozzles having smaller orifices and larger angles B.

If desired, the construction shown in Fig. 4 may be employed in order to produce counterflow of gases within the combustion chamber 20a, thus facilitating uniform mixing of atomized fuel with the air under pressure admitted from the passageway l2. According to this form of the invention, the shaft 22 is adapted to carry an impeller member ll comprising a central portion ll having an annular entryway l2 and provided with radially disposed passages 43 adapted to supply fuel under centrifugal pressure, as hereinbefore explained. Extending outwardly from the central portion 4! of the impeller member I. are a plurality of circumferentially spaced arm portions N, the outermost ends of which are adapted to carry the nozzles 3|. Each arm portion 44 has oppositely warped vane sections ll. 41 and ll, which are disposed on that part of the arm which travels within the combustion chamber 20a, as shown in Fig. 4. Referring to Fig. 5, the arm portions 44 may be reinforced by a suitable shroud ring II, which is adapted to be arranged concentrically within the entryway 29 of the basket structure 20. As best shown in Figs. 6 and 7, the respective inner and outer vane sections it and J. are so warped with respect to the direction of operative rotation of the impeller member 40 as to cause flow of air in a downstream direction, in the combustion chamber a, while the centrally disposed blade sections 41, aligned with the nozzles 3|, are warped in the opposite direction in order to produce counterflow of a current of air-in an upstream direction, or against the jets of fuel spray discharged from the rotating nozzles 3|. By thus constructing the arm portions 44 for providing blade sections warped in opposite directions, as just explained, the middle vane sections are operative to effect counterflow of air for insuring thorough'mixture with the fuel spray discharged from the nozzles, while the outer vane'sections are operative to propel the mixed air and fuel in a downstream direction into the flame zone of the combustion apparatus, thereby insuring uniform burning of the fuel.

From the foregoing, it will now be seen that the improved fuel distributing apparatus may be employed in a gas turbine power plant to insure uniform circumferential distribution of fuel spray in an annular chamber without production of hot spots in the combustion apparatus. Although the fuel pressure at the rotating nozzles, due to' the effect of centrifugal force, will be sufiiciently high to render feasible the use of nozzles having relatively large flow areas, the improved fuel supply apparatus will require only a low pressure fuel feeding means adapted to insure flow of fuel into the annular entryway of the rotary impeller member. Inasmuch as the residual fuel remaining in the communications within the impeller member when the power plant is shut down will be negligible, the presence of a dump valve in the fuel system will be unnecessary.

While the invention has been shown in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.

What is claimed is:

1. Fuel combustion apparatus comprising a casing forming an annular passageway adapted to accommodate flow of air under pressure, an axially disposed rotary shaft journaled in said casing, an annular structure forming a combustion chamber supported concentrically in said passageway, said structure having a lateral annular entryway formed in the upstream end thereof and communicating withsaid passageway, rotary fuel impeller means carried on said shaft and adapted to extend radially through said entryway intosaid combustion chamber, nozzles carried on said impeller means for directing fuel downstream in said combustion chamber, said nozzles being inclined inwardly at an angle with respect to the rotational axis of said impeller means, and means including radial communications in said impeller means for supplying fuel under centrifugal pressure for atomization by way of said nozzles.

2. Fuel combustion. apparatus comprising a casing forming an annular passageway adapted to accommodate flow of air under pressure, an axially disposed rotary shaft journaled in said casing parallel to the path of air flow, an annular structure forming a combustion chamber supported concentrically in said passageway, said structure having an annular entryway formed in the upstream end thereof and communicating with said passageway, rotary fuel impeller means carried on said shaft and including radial fluid translating vane portions extending through said entryway into said combustion chamber, nozzles carried on said impeller means within said combustion chamber and inclined inwardly relative to the axis of said impeller means, and communications formed in said impeller means forsupplying fuel to said nozzles under centrifugal force, whereby fuel is atomized in said combustion chamber and uniformly mixed with air impelled by said vane portions.

3. Fuel combustion apparatus comprising a casing forming an annular passageway adapted toaccommodate flow of air under pressure, an axially disposed rotary shaft journaled in said casing, an apertured annular structure forming a combustion chamber supported concentrically in said passageway and receiving-therefrom a main stream of air flowing in a downstream direction, said structure having a lateral annular entryway formed in the upstream end thereof and communicating with said passageway, fuel impeller means carried on said shaft in operative alignment with said entryway, nozzles carried by said impeller means for atomizing fuel in said combustion chamber, said impeller means having concentric annular groups of radially extending vane surfaces, each vane surface of one group being warped with its leading edge pointed downstream relative to the combustion chamber for effecting local counterflow of air toward said nozzles, and each vane surface of the adjacent group being oppositely warped with its leading edge pointed upstream for effecting downstream flow of air and admixed fuel along with the main stream of air within said combustion chamber.

4. Fuel combustion apparatus comprising a casing forming an annular passageway adapted to accommodate flow of air under pressure, an axially disposed rotary shaft journaled in said casing, an annular apertured structure forming a combustion chamber supported concentrically in said passageway, said chamber receiving air flowing in a generally downstream direction, said structure having a lateral annular entryway formed in the upstream end thereof and communicating with said passageway, and rotary fuel impeller means carried on said shaft in operative alignment with said entryway, said inipeller means including a plurality of nozzles canted inwardly relative to the axis of said impeller means for atomizing fuel in said combustion chamber, and a plurality of radially extending vane surfaces carried on said impeller means within said combustion chamber, each of said radial vane surfaces being disposed at a pitch angle with the leading edge thereof directed downstream for effecting local counterflow of air adjacent said nozzles facilitating uniform mixture of atomized fuel and air prior to merging of the mixture with the air flowing through said chamber in the downstream direction.

REINOUT P. KROON.

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

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