US2607193A

US2607193A - Annular combustion chamber with multiple notched fuel nozzles

Info

Publication number: US2607193A
Application number: US782163A
Authority: US
Inventors: Lloyd E Berggren; Miller David
Original assignee: Curtiss Wright Corp
Current assignee: Curtiss Wright Corp
Priority date: 1947-10-25
Filing date: 1947-10-25
Publication date: 1952-08-19
Anticipated expiration: 1969-08-19

Description

g- 1952 L. E. BERGGREN ETAL ANNULAR COMBUSTION CHAMBER WITH MULTIPLE NOTCHED FUEL NOZZLES 2 SHEETS -SHEET 1 Filed Oct. 25, 1947 ATTORNEY 1952 E. BERGGREN ETAL 2,607,193

ANNULAR COMBUSTION CHAMBER WITH MULTIPLE NOTCHED FUEL NOZZLES Filed Oct. 25, 1947 2 SHEETSSHEET 2 -spaced streams. nozzles'in an annular combustion chamber,-the "one fuel stream of each'nozzle can be directed Patented Aug. 19, 1952 UNITED STATE-S lsRATEi-NT orri .ANNULAR COMBUSTION CHAMBER NVITH .MULTIPLE NOTCHED FUEL 'NOZZLES J Lloyd;E.;B.erggren, Roseland, N.lJ., and David ,-Miller,gLynchb urg, -Va.,; assignors; to Curtiss- Wright Corporation, a corporation of Delaware Application'october 25, 1947, Serial No. 782,163 A Claims. (area-39.74)

This invention relates to liquid spraynozzles --and is particularly directed to a liquidiueknozzle structure for combustion apparatus.

The conventional fuel-nozzle .forliquid fuels is provided with means for imparting a whirling or rotary motion-tothe fuel before it discharges In -lan- -actual installation with said conventional fuel nozzles, it has been found that the temperatureof the combustion gases, at the annular discharge end 'ofthe combustion chamber, is a maximum at the mean radius of-said annular discharge end and-is a minimum at the-inner and outer radii-of saidannular-discharge end. --However,- since in general-the efficiency of agas turbineincreases with increase in the averagertemperatureof the turbinemotive fiuid this non-uniform temperature distribution results in a correspondingtde- ---'crease in turbine efiiciency. -Accordinglytitis .an object of this I invention-to:providea fuel nozzle having a fuel spray-pattern.such that when a -plurality-of such nozzlesare-used in an annular combustion chamber of agasturbine, the combustion-gases have a more uniform or a more-desirable temperature distribution at'theEdischarge -end-of the combustion chamber.

- A still further object I of i the 1 invention: resides in the provision of a fuel nozzle having a fuel spray comprising two diverging diametrically With a plurality .of such iuel toward the inner'wall of-the combustionichamher with the other fuel stream ofsaid nozzle directed toward the outer wall of said combustion chamber whereby the temperature I pattern of the combustion gases canbe improved.

In conventional gas turbinepthe combustion gases are directed from the-combustion chamber against blades extending radially from a'turbine rotor. During operation,"the turbine'rotor blades are subjected toycentrifugal forces'and to the of :the blades and said stress progressively de- -creases toward the radially outer ends of'the blades. Therefore the maximum safe tempera- -ture at which the turbine rotor bladescan be operated progressively increases from a point adjacent -the:root ends of the blades-t0 their radially outer ends. With this inmind,-a still further object of the invention comprises the --provision of a' fuelnozzle having a spray pat- .10" -tern such that whena plurality of such nozzles areusedin an annular combustion chamber, the

' temperature :of the combustion gases, at. the

annular-dischargeend of said chamber, is amaxi- Jnum at the :maximum radius of said chamber :anddecreases radially inwardly therefrom.

A still further object of the invention com- :prises the provision of :an'annula'r combustion chamber havinga plurality of circumferentially spaced fuel nozzles at the inlet end of-s'aid chamber with each fuelnozzle designedto provide a .spray pattern comprising one fuel stream inclined to the nozzle axis and directed toward the innerwall of said combustion chamber and a second: stream inclined to the' nozzle axis and directed toward the outer wall of saidcombustion a chamber.

" Other objects of. the invention will .become apparent upon reading the annexed detailed devscriptionv in connection with the drawing, in

which: 7 s

Figure 1 is an .axialasectionalview of a gas-tursbinelcombustion chamber having :fuel nozzles embodying the invention;

.=i'-Figure"2 isan enlarged sectional view taken :along'line 2--2 of Figurell; 1

-Figure- 3 is afurtherenlargedsectional View g of ai'uelnozzle incorporated in Figures 1 a and 2 Figure -4:is anend View ofa fuelnozzle taken along line 4 -4 of Figure '3 Figure 5 is an end view of the swirl piece of the fuelnozzleofFigures 3 and 4;

Figure -G is an end view of a nozzle generally similarto'that of Figures 3, 4 and 5;"

Figure 7' is a partial sectional viewtaken along line 1-1 of Figure 6;

* Figure Bis a; partialsectional view of anozzle similar'to-that of'Figure 3' but providing a slightj ly differentspray pattern;

*Figure- 9 is an end View taken along line 8-9 Figure lfl is a partialsectional view oranoz- "Figure 11 isan' endview taken alongline -l I--ll of Figure -10; 1

Figure 12 is a sectional view through a different form of fuel nozzle embodying the invention; and

Figure 13 is a view taken along line I3--I3 of Figure 12.

Referring first to Figures 1 and 2, reference numerals ID indicate an annular combustion chamber of a gas turbine engine. Applicants copending application Serial Number 782,162, filed October 25, 1947, schematically illustrates such a gas turbine engine Air is supplied under pressure to the annular inlet opening I2 of said chamber. A plurality of fuel nozzles I4 are circumferentially spaced about the combustion chamber inlet opening I 2 from which fuel under pressure is sprayed into said chamber.

A short duct I6 is co-axially disposed about each nozzle I4 and, at the inlet end of the duct I8, vanes I8 are disposed so as to impart a whirling motion to the air entering said duct. An

additional set of vanes 20 are disposed about each of said first set of vanes I8. The vanes 20 are positioned so as to impart a whirling motion to the air flowing therebetween opposite to that imparted by the first set of vanes I8. This radially inwardly of each nozzle I4 and its duct I6 to form a second annular shield. The

annular shields

22 and 24 are spaced from their adjacent combustion chamber walls and they overlap annular shields 28 and 28 a short distance down-stream from the fuel nozzles I4. The

shields

22, 24, 26, and 28, are spaced from the adjacent combustion chamber walls to permit air flow therebetween, thereby maintaining the outer combustion chamber walls ,relativelycool. The combustion chamber is also provided with conventional igniter means (not shown) -'as for example electric spark gaps-in order to ignite the combustion mixture.

The structure of the combustion chamber so far described forms no part of the presentinvention. With the usual fuel nozzles, each nozzle atomizes or sprays fuel into its combustion chamber in a conical hollow spray pattern. It has been found that with such conventional nozzles, the temperature of the combustion gases at the annular discharge end of the combustion chamber, is a maximum atthe mean radius of said discharge end and isa minimum at the inner and outer radii of said end. This temperature distribution probably results from overlapping of the hollow conical fuel spray patterns of the nozzles along the mean radius of the combustion chamber as well as from the relatively cool air flowing along the inside walls of the shields 26 and 28.

In accordance with the present invention each nozzle I4 is designed so that its spray pattern comprises two diverging diametrically opposed fuel jets or streams with each particle of fuel in said spray pattern having radial and axial components of velocity relative to the axis of its nozzle. In addition each nozzle is disposed in the annular combustion chamber I so that its two fuel streams are substantially symmetrically disposed relative to a plane including the axis of tral bore 34 in said nozzle.

the combustion chamber I8 and the axi of the associated nozzle vI 4.

The nozzles 14 are all the same so that it is only necessary to describe one of the nozzles. Referring to Figures 3 to 5, the nozzle 14 is threaded on the end of a fuel conduit 32 from :which fuel is supplied under pressure to a cen- The bottom of the nozzle bore 34 is conical as indicated at 36. A swirl piece 38 is threadedly secured within the nozzle bore 34 by its threads 48. The downstream end of said swirl piece is formed as a frustrum of a cone which is fitted to and is held against the conical bottom 36 of the bore 34 thereby forming a chamber 42 at the bottom of said bore. The swirl piece threads 48 are provided with one or more axial grooves 44 through which fuel flows to' the bottom of the bore 34. In addition the conical end of the swirl piece 38 is provided with a plurality of circumferentially spaced grooves 46. Each of the grooves 46 extends from the outer edge of the conical end of the swirl piece 38 and terminates substantially tangent to the outer periphery of the chamber 42. In this way fuel enters tangentially into the chamber 42 from the fuel passages formed by the grooves 46. Each of the grooves 46 is directed in the same direction about the axis of the chamber 42 whereby fuel tends to whirl in the chamber 42 about the axis of said chamber. The nozzle end wall adjacent the chamber 42 is provided with a small discharge orifice 48 co-axial with the chamber 42. If the outer surface of the nozzle I4 about the orifice 48 is symmetrical, in all directions, the'whirling motion of the fuel discharging through each discharge orifice 48 causes each nozzle to have a hollow conical spray pattern.

In accordance with the present invention the outer surface of each nozzle I4 is provided with a pair of notches 50 extending in diametrically opposite directions from its discharge orifice 48. As illustrated in Figure 4, the notches 50 are similar and the width of each notch 50, adjacent its orifice 48, is approximately equal to the diameter of said orifice 4B. The side walls of each notch 50 diverge in a radially outward direction from its orifice 48 so that the width of each notch 50 is a maximum at its radially'outer end. The angle A, included between the side walls of each notch 50, is approximately 30 as illustrated in Figure 4. The depth of each notch 50 is a maximum at its orifice 48 and said depth progressively decreases in a radially outward direction from said hole. Such diametrically opposed notches 58 may readily be machined in the outer surface of a nozzle I4 by means of a cylinder cutting tool.

Because of the whirling action of the fuel about the axis of its nozzle discharge orifice 48, the fuel discharging therethrough is subjected to centrifugal forces so thaton leaving its nozzle, each particle of fuel has a radial as well as an axial component of velocity. The notches 58 split the fuel discharging from their discharge orifice 48 into two similar diametrically spaced diverging streams as indicated at 52 (Figures 1 and 2). For clarity, the fuel streams 52 have only been indicated for one nozzle in Figure 2. As a result of the whirling action of the fuel, a plane, including the axes of the two fuel streams 52-discharging from each nozzle, is inclined by an angle E (Figure 2) to the directional; which said notches 50 extend from the axis of its discharge orifice 48. The rotative displacement of this plane of.;a'.pair. of fuel streams 52r -fromithe direction ofa theirinotcheszifl isthe same as. the direction of. :thewhirlingaetion of. the fuel' discharging through its nozzle orifice 48-: Eachnozzle. is disposedinthe combustion-chamber so-that a'plane includingiits. axis and-the axis-lof saidcombustion chambenpasses. symmetrically throughits two fuelzstreams 52; This. means that each nozzle is: disposed in the combustion chamber so that the directionatwhichits notches 50 extend from itsorifice 48 is inclinedby said angle B vto aradial line passingthroughtheaxis of said combustion chamber. and. the :axis of said: orifice.

' .Inzan actual installation, with the angle Aequal to 30 it was found thatthe angle B=was roughly 10 to 15 Therefore, as illustrated. in. Figure 2,. each...nozzle I4 :is disposed in thecombustion chamber so that its notches 58 extendiromits nozzle'dis'charge orifice along a linemakingzanangle B, equaltosapproximately to with a line radial to the axis of the combustion chamber and passing through .said'discharge orifice'i48; With this construction, each pair" of fuel.- streams 52 discharging from. a nozzle i4 is symmetricallyrdisposed relativeto aplaneinclud ing. the axisof theannular combustion chamber l0 'an'dthe axis .of its fuel nozzle l4. That is,the one fuel. stream or flame 52, emanating. from the orifice 48 of a nozzle 14, is. directed axially 1- and radially from the nozzle toward the outer wad of the combustionfchamber i4 while the other v fuel. stream or flame 52,. emanatingsfrom' said: nozzle orifice, is directed axially. andradiall'y from the nozzle toward the inner wallof the combustioncham-ber l4. With this arrangement, a more uniform. temperature of .the combustion. :gases .is produced. at. the discharge end: of the combustion chamber..

The specific form of the nozzle notches-Sandepends. onrthe partlcularrspray pattern desired which, in the case of a fuel nozzle, depends. on

the dimensions. of the combustion chamberto whichfuelis supplied by the associated nozzle;

In 'aconventional gas turbine, the turbine rotor blades eXtendradially from the turbine. rotor. across the annular' discharge end of the turbine combustion chamber. In thisconventional structure, the stress in each turbine blade, during turbineioperation, is: a: minimum at the radially outer end or tip. of theblades and said stress increases toward the root ends of the blades. Therefore the maximum safe operating temperature of the turbine rotor blades is higher at the radially outer ends of the blades and decreases radially inwardly therefrom with increase in the stress in the blades. Accordingly, in the case of a gas turbine, the temperature of the combustion gases at the discharge end of the turbine preferably is a maximum at the maximum radius ofsaid dischargeend and decreases toward the minimum radius of said discharge end. This temperature distribution may be produced by making'the fuel stream directed toward the outer wall of the combustion chamber larger than the fuel stream directed toward the radially inner wall 'ofthe combustion chamber. Figures 6 and 7 illustratea nozzle 60 having a spray pattern comprising two such non-equal fuel streams.

The nozzle 60 is similar to the nozzle [4 except its notches 62, on the outer surfac of said nozzle v6ll,'in effect are displaced relative to the axis of the nozzle discharge orifice 64. Thus the notches a With. the nozzle. to: disposedin.the'ipositionrillus-r trated inFigures- 6 land 7, the notches.62: extend.- in a vertical. direction and the minimum: width" portion of said'notches is disposed below the axis 1 of itsdischarge orifice 64 and-;..with-said:nozz1e in. this position, its upper fuel stream .is-xlarger. or contains morefuel than its. lower fueLstream;

Accordingly iniaz gas turbine installation, each;

nozzlev Bil is disposed in. the turbine combustion. chamber. withits notches .G2.making. anuang-le with a-radial line passing through thecombustion. chamber axis and the axisof its-nozzle :(as Lilluse; tratedin: Figure 2) andrwith .the. minimumidif-rr ameter portionof the notches :62 disposed closer. to the: axis of the combustion chamberthan is; the axis 0ffitS.nOZZ1e.1 Withzxthis arrangement: the :temperaturer'of the =combustion-:gaseshat the;

discharge .end'ofLthe combustion chamber. may

be made a maximum: at. the maximum. radius.:,of;

said discharge end.

Figures 8 and 9 illustrate aifuel nozzle flflisimilar to that of Figures 3 to :5 exceptthe angleA. between the sides. of each of. the .diammetric'ally; opposed notches 12, is. made equal tozero.i;.Th-e..

1 remaining parts of the nozzle 'Hlare similanto:

those of the nozzle 14 of Figures 3 .to 5;

Figures 10 and 11 illustrate a fuel nozzletlik which comprises a further modification ofjtthe: fuel nozzle I 4 of Figures 3 to 52. .In Figures. lOand 11 the sides of the diammetrically opposed notches 76, like the sides ofthe notches 50 divergein'a radially outward directionbyanv angle. A but. the depth of. each of the notches 50" is constant- The remaining parts of the fuel nozzle 14 arexsim ilar to those of the fuel nozzle l4.

The fuel nozzles 10 and 14 both provide spray. patterns generally similar to that provided. by the nozzle l4 inthat each of these nozzles provide a spraypattern similar to that schematicallyillustrated in Figure l. The spray, pattern of the nozzle 10 differs from thatof the nozzle l4 in-thatthe pattern is narrower-in a direction transverse to the notches 12, while thespraypattern of the nozzle 14 diverges considerably morethan the spray pattern of the nozzle l4; Figures 3.:to.5. illustrate the preferred fuel nozzle notch: con struction for a nozzle havinga fuel spray pattern. comprising two diverging fuel streams ofequal strength while Figures (Sand-7 illustrate a modi fied construction in which the fuel spraypat.-. tern comprises two diverging fuel streams'ofpuntequal strength:

Theinvention is not limited to the specifictypeof nozzle illustrated in detail in Figures-3 to 5.. For example, Figures 12 and 13 illustrate the invention applied to another form of nozzle 80 threaded on the endof a fuel conduit 82.. A nozzle orifice member '84 extends through the endawall. 86 formed by a counterbore 88 in the nozzle. The orifice member 84 has anext'ernal annular flange 90 which is held against the-end wall 86 by. an

intermediate member 92 and amemb'er 94 thread-- 62 are generally similar to the notches 50 except edly secured within the bore '88. Themember. 94-ishollow and is provided with a'plurality' ofradially disposed holes 96 through whichfuel-is supplied to the bottom of the bore. 88-from the conduit 82. The engaged surfacesof the members 84 and 92 are fiat. The surface of: the member Bil engaged by the member 92 is provided with a plurality.- of cir'cumferentially spaced grooves 91 extending inwardly from the outer periphery of said surface to a chamber 98. These grooves terminate substantially tangential relative to the outer periphery of the chamber 98.

With this construction of Figures 12 and. 13,

fuel enters the chamber 98 in a tangential direction and therefore said fuel tends to whirl about the axis of said chamber and the nozzle orifice I through which theifuel discharges. In addition the outer surface of the nozzle orifice member 84 is provided with a pair of notches I02 extending in diametrically opposed directions from the nozzleorifice 100, said notches preferably being similar to thenotches '50 of Figures 3 to 5 orthe notches 62 of Figures 6 and 7. Accordingly it should be clear that the nozzle of Figures 12 and 13 will provide substantially the same form of spray pattern as that provided by the nozzle of Figures 3 to 5 or the nozzle of Figures 6 and '7. In the structure of Figures 12 and 13, the discharge end of eachlgroove 91 is directed along a line which does not intersect the axis ofits nozzle orifice .100 and which isinclined at right angles to said axis instead of obliquely as inthe structure of Figures 3 to 5.

While we have described our invention in detail in its present preferred embodiments, it will be obvious to those skilled in the art, after understanding our invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. We aim in the appendedclaims to cover all such modifications.

We claim as our invention:

1. In combination: an annular combustion chamber; a plurality of fuel nozzles disposed in said chamber and circumferentially spaced about the axis of said chamber, each of said nozzles having an end Wall witha discharge opening through which fuel discharges into said combustion chamber and at least the discharge end of the discharge opening of each nozzle being elongated diametrically across the nozzle axis, each of said nozzles being oriented so that the plane defined by its nozzle axis and said diametrical direction of its elongated discharge opening is approximately radial relative to the axis of said combustion chamber.

2. In combination: an annular combustion chamber; a plurality of fuel nozzles disposed in said chamber and circumferentially spaced about the axis of said chamber; each of said nozzles having an end wall with a discharge opening through which fuel discharges into said combustion chamber and at least the discharge end of the discharge opening of each nozzle being elongated diametrically across the nozzle axis;' and means within each nozzle for causing fuel discharging through its discharge opening to whirl about the nozzle axis'whereby said elongated dis-,

charge opening is effective to produce :a fuel spray pattern havin a maximum divergence in a plane including the nozzle axis but rotatively displaced about said nozzle axis by an acute angle B in the direction of said whirl from a planeincluding said nozzles axis and the diametrical direction of its elongated discharge opening, each of said nozzles being oriented 'so that said plane of its elongated opening is rdtatively displaced about the nozzle axis in a direction opposite to said whirling motion by said acute angle B from a radial plane including said nozzle and combustion chamber axes so that said fuel stream plane of maximum divergence is substantially radial relative to the axis of the combustionchambenl 3. Incombination: an annular combustion chamber; aplurality: of fuel nozzles disposed in said chamber and circumferentially'spaced about.

the axis of said chambenleach of said-nozzles having, an end wall. with' a dischargeflorifice through which fuel discharges into said.'combustion chamber, the outer surface of each said nozzle end wall having .a pair of notches extending in substantially diametrically opposite directions from the associated nozzle discharge orifice; and means within each nozzle for causing fuel discharging through its discharge orifice to whirl about the axis of said orifice whereby each pair of nozzle notches are effective to cause fuel to discharge from the associated nozzle orifice in apair of substantially co'-p1anarv streams diverging from each other with the plane of the-axes of each pair of fuel streams being rotatively displaced about the axis of nozzle discharge orifice from a plane including said nozzle axis and said diametrical direction of its associated 'pair of notches, said rotative displacement of the plane of the pair of fuel streams, of each nozzleibeing equal to an acute angle B and being in the direc; tion of said fuel whirling, motion about the axis of said nozzle, eachof said nozzles being oriented so that said plane of its notches is rotatively. displaced about the nozzle axis by said acute angle B from a radial plane including said nozzle and combustion chamber axes-and in' a direction opposite to. said whirling motion so that said fuel stream plane is substantially radial relative to the axis of said combustion chamber. i

4. In combination: an' annular combustion chamber; a plurality of fuel nozzles disposedin said chamber and circumferentially spaced about the axislof said chamber; each of said nozzles. having an end wall with a discharge orifice through which fuel discharges into said combustion chamber, the outer surface of each nozzle end wall having a pair of notches extending in substantially diametrically opposite directions from the associated nozzle discharge orificeand each of said nozzles being oriented so that the plane defined by its nozzle axis and the diametrical direction of its said-notches is approximately radial relative to the axis .of said combustion chamber. Y 1.

LLOYD E; BERGGREN.

DAVIDMIILER.

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

UNITED STATES PATENTS- Number I Great Britain j June 26, 1915