US2945629A - Fuel injection nozzle for a gas turbine engine - Google Patents

Description

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July 19, 1960 R, CHUTE ET AL 2,945,629

FUEL INJECTION NOZZLE FOR A GAS TURBINE ENGINE Filed May l2, 1958 Eig-4.5. fij 2f 57d 27 3 INVENTORS. 5 1 E if; 23 z'fdr/ vh/?, 3 g' g 15g/fw? 125g/mm@ FUEL INJECTION NozzLEFoR A GAS TURBINE ENGINE Richard Chute, Huntington Woods, and Ernest J. Bunning, Ferndale,Mich., assignors to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Y Filed May 12, '1958, ser'. 10,734,637

1s claims. (c1. z39-424) 4This invention relates to an air-fuel atomizing nozzle yadapted tobe used with `a gas turbine liquid fuel vcontrol system and is a'n improvement over the structure disclosed in Patent No. 2,863,700 of William A. Ziemke.

Various types of fuel-'air Iatomizing nozzles lavailable to the art -are effective to provide a combustible spray pattern of liquid fuel particles. Such nozzles require either fuel and fair pressures of considerable magnitude or a large air mass flow if the air pressure is reduced. The size and capacity of the iluebair pumping unit must be correspondingly large. Further, when the nozzle is used with la gas turbine fuel control system, the operating speed range throughout which adequate fuel 'dispersion can be obtained is undesirably narrow.

Certain of the prior art nozzles `are provided with an internal mixing chamber within the nozzle assembly to facilitate the mixing of air and liquid fuel. A considerable restriction i-s encountered by the fuel-air mixture before it is discharged into the combustion chamber associated with the nozzle. The unfavorable characteristics of such nozzles are believed to be due in part to the fact that mixing of the fuel `and `air takes place internally of the nozzle assembly.

These and other disadvantages are overcome in accordance with the present invention by providing a new and improved nozzle wh-ich incorporates` separate fuel and air passage means having intersecting branch portions. Air is conducted through the 'air branch portions and is effective to shear or break up a controlled how of liquid fuel within the fuel branch portions at the regions of intersection of the fuel and air branch portions.

According to an important feature of the present invention, the fuel branch portions `are effective to conduct liquid fuel to an external location near a terminal portion olf the nozzle assembly. The yair branch portions are adapted to intersect the fuel branch portions in the vicinity of the nozzle terminal portion at a location which is exterior of the nozzle assembly. The liquid fuel i-s thereby atomized by the air externally of thelnozzle rather than in an internal mixing chamber or in internal nozzle passages. The resulting spray or distribution pattern is comprised of fuel particles which are more yfinely dispersed than the pattern obtainable with conventional nozzles at a comparable air pressure k'and air flow.

ln the above regard, nozzles of the internal mixing type frequently depend on a swirl chamber immediately preceding the nozzle discharge orifice. The resulting fuel-air spray pattern is substantially a solid cone which in certain types of turbine engines inhibits combustion of the fuel particles near the center of the cone and also enables 'an 'accumulationof liquid fuel particles adjacent the exterior of the discharge nozzle which' drip and. cause undesirable carbon deposits.

An object of the present invention is to achieve Ia substantially hollow cone fuel-air dispersion or spray pattern which not only renders the fuel more susceptible to combustion, but requires Iappreciably less air for atomi- 2,945,629 Patented July 19, 1960 zation than in conventional nozzles and minimizes drip of liquid fuel from the nozzle extremity. Another object is to provide a new land improved liquid fuel and Iair atom-izing nozzle which is simple in construction, inexpensive to manufacture and character'- ized by improved nozzle mixing properties.

Another object of the present invention is to provide a new `and improved fuel-air 4atomizing nozzle for use with the icombustion `chamber of ya liquid fuel com# bustion apparatus, which is adapted to provide a co`m= pletely Iatomizcd spray or fuel-air distribution pattern throughout Ia wide range of controlled variations in the rate of fuel consumption.

Another object is to provide a fuelJair atomizing noz zle of improved eiiiciency which requires relatively fuel and air pressures vand a comparatively low air mass iiow with respect to conventional nozzles.

Another and more specific object is to provide an inii proved =fuelair atomizing nozzle Istructure having a cylin drical distributor eiement received within a nozzle body. T he distributorelement is provided with an endwise coni verging conical terminal portion which -extends to the exterior of the body. A plurality of fuel passage grooves extend in the outer surface of the terminal portion from within the body to its exterior and are intersected at locations exterior-1y of the body by branch 4air passages which extend substantially normally to the grooves and communicate with a central air chamber Within the distributor element, The ai-r chamber and fuel. passage grooves lare connected withinvthe nozzle structure to sources of fuel `and air respectively under pressure. In addition, a spray plate is provided which extends transversely `across the grooves in parallelism with the direction of discharge of air into the grooves from the branch air passages and blocks the grooves at locations adjacent and endwise of their intersections with ,thebranoh passages. The aforesaid Vair chamber is located coaxialj ly Within the terminal portion and opens -endwise to receive the spray plate, by a press lit therein. By virtue of the foregoing structure, major simpli'etions, and economies in 4fabrication and assembly are enabled and an optimum {atomization and a preferred spray pattern are achieved. p u Y One of the major problems involved in the manu'- factu-re of fuel-air atomizing nozzles of the type which include intersecting fuel `and `air branch', passages 'arf ranged to cause shearing and atornization of the fuel as it leaves the nozzle assembly is the alignment ofthe aforesaid intersecting passages. Here'tofore fuel passage grooves have been milled in the exterior of the nozzle distributor element'. Air passages have then been drilled into the distributor element so las to intersect the fuel passage grooves and the central lair chamber within the distributor. Considerable `diiiiculty Iand expense have been encountered in maintaining the close dimensional tolerances required, particularly at the location of inter# section of the air and fuel branch passages.

It is accordingly another object of they present invention to provide an improved and simplified method for manufacturing such nozzles', wherein the central air chamber is formed circul'arly and colaxially Within the cylindrical distributor element `adjacent one end thereof, and the fuel passage' grooves are milled in the exterior surface of the `distributor adjacent said one end. The central circular chamber is formed sufficiently large the grooves are milled sufficiently deep so `as to intersect the chamber. Thus the branch air passages are automatically provided i`n` proper alignment intersecting the grooves so' asl to' supply air for shearing `and afornizing liquid fuel flowing along" the grooves.

The foregoing method enables the overall nozzle tributor to be' formed economically by yautonnat'ie screw machines. The grooves can be milled at any circumferential location in the terminal portion of the distributor element. By controlling the dimensions of the grooves and of the control chamber, the dimensions and locations of the branch air passages between the central air chamber and the fuel passage grooves are readily controlled. Correct alignment is thus assured without necessitating precise indexing of the distributor element.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

lFigure l is a view partly in elevation and partly in longitudinal mid-section showing a nozzle `assembly and holder embodying the present invention.

Figure 2 is an enlarged end view of the distributor element and spray plate removed from the nozzle body, taken in the direction of the arrow 2 of Figure 3.

Figure 3 is a longitudinal section taken in the direction of the arrows substantially along the line 3-3 of Fignre 2.

Figure 4 is a fragmentary view similar to Figure 3, with the spray plate removed.

Figure 5 is an end view of the spray plate removed from the distributor element, taken in the direction of the arrow along the line 5 of Figure 3.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of `being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring to Figure l, a nozzle assembly embodying the present invention is illustrated by way of example nular fuel passage in communication with passages 15, 16 to receive fuel therefrom and will be referred to hereinafter as fuel passage 23.

The forward end of distributor 25 comprises an enlarged terminal portion 27, Figure 3, which converges endwise conically from a shoulder 28 located within the body 22 and extends to the exterior thereof. The conical outer surface of the terminal portion 27 extends in parallelism with the conical interior surface of flange 24 and seats against the latter to close fuel passage 23 except at the regions of eight grooves 29 formed in the outer surface of portion 27. The number and arrangement of the grooves 29 will obviously depend on the engine fuel requirements.

with a T-shaped nozzle holder having a cylindrical portion 10 and an integral transverse bracket 11. The portion 10 is provided with a central bore 12 which extends into the bracket 11 and opens at a threaded socket 13 adapted to receive a conventional fitting for attachment with a source of pressurized air. Forwardly of the bracket 11, the bore 12 opens into a cylindrical enlargement 14 which in turn opens into a still greater cylindrical enlargement 15. The latter is in communication with a fuel passage 16 extending axially from portion 10 into bracket 11 and opening at a threaded socket 17 suitable for attachment with the source of fuel under pressure. The shoulder between the portions 14 and 15 is chamfered at 18 to provide a conical seat for an annular spring type seal 19, which may comprise a Belleville washer.

Endwise of the enlargement 15, the bore of the cylindrical portion 10 is reduced and threaded at 20 to receive the reduced threaded end 21 of a cylindrical nozzle body 22. The latter is provided with a coaxial cylindrical opening 23 extending substantially its full length but being restricted slightly at its forward end by an integral conically converging flange 24. Extending coaxially within the cylindrical opening 23 is a cylindrical distributor element 25 having a reduced rear end portion 26 closely fitting within bore 12 rearwardly of the enlargement 14.

Within the latter enlargement, the outer wall of the distributor 25 enlarges conically in parallelism with the conical chamfer 18 so as to seat against the inner portion of spring seal 19. The seal 19 is under tension yieldingly engaging the conical chamfer 18 and the adjacent conical enlargement of the distributor 25 and thus serves both to separate the fuel passages 15 and 16 from the air passage 12 and also to urge the distributor 25 yieldingly forwardly against the flange 24, as described below, thereby to provide means to compensate for differential thermal expansion between the nozzle elements. The portion of opening 23 around the distributor 25 comprises an an- For larger engines, the total circumferential extent of the grooves 29 will increase until in the limiting case, a corresponding full conical fuel passage will extend in the outer surface of portion 27. In the present instance, grooves 29 extend in equallyspaced radial planes through shoulder 28 so as to communicate with fuel passage 23 and also extend to the forward extremity of terminal portion 27, Figures 2 and 3.

Extending coaxially through the cylindrical distributor 25 is an air passage or bore 30 having an enlarged portion 30a adapted to receive the stem 31 of a spray plate described below. As indicated in Figure 5, the stem 31 is of elongated section having opposite cylindrical end portions 31a press fitted snugly into bore portion 30a and having opposite flattened portions 31h provided to enable free passage of air past stern 31 from air passage 30 into enlargement or passage 30a. Endwise of passage 30a, the central passage of distributor 25 enlarges conically at 32, then extends cylindrically at 33, then enlarges conically at 34, Figure 4. Forwardly of stem 31, the body of the spray plate is restricted at 35, then enlarges cylindrically at 36 to provide an annular air passage or chamber 38 therearound in bore portion 30a. Forwardly of the enlargement 36, the spray plate enlarges conically at 39 in parallelism with the conical enlargement 34 and seats snugly thereagainst to close the endwise opening of passage 30a. Also as illustrated in Figure 3, the conical enlargement 32 is substantially parallel to the interior surface of the conical enlargement 39, thereby to provide a conical endwise diverging air chamber 40 extending from passage 38 and opening at branch passages 40a into one of each of the grooves 29 at a location externally of the body 22, Figure 1. The peripheral portions of the conical spray plate 39 extend transversely and substantially normally to the grooves 29 to block the latter adjacent and endwise of the branch passages 40a.

In operation of the nozzle, fuel is supplied under pressure via passages 17 and 16 into enlargement 15 and thence along the annular fuel passage 23 around the outer cylindrical surface of distributor element 25 to the grooves 29, whereat the flange 24 directs the fuel endwise along the grooves 29 to the exterior of the nozzle body. Air is supplied under pressure via conduits 13 and 12 to the bore 30 of distributor 25. From bore 30, air passes around the flats 31b of the spray plate stem 31 and into chambers 38 and 40, which latter provides the branch air passages 40a intersecting grooves 29. Air discharging from branch passages 40a substantially perpendicularly to the direction of fuel flow along grooves 29 shears the fuel from the grooves and effects a substantially endwise diverging air-fuel atornized spray pattern externally of the nozzle. The conical surface of the spray plate 39 blocking the grooves 29 prevents the possibility of fuel passing in the direction of the grooves 29 beyond the region of the branch passages 40a, thereby to assure complete dispersion of the fuel and also to prevent the possibility of formation of liquid fuel droplets at the terminal portion of the distributor.

It is also to be noted by virtue of the foregoing that with the exception of the grooves 29 which are preferably milled into the terminal portion 27 the distributor element 25 with its conical endwise enlarging chamber portions as n.5

32,33, and 3ft can be readily formedrby automatic screwY machines. The grooves 29 are then milled or broached so as to intersect the cylindrical enlargement 33. However the grooves 29 can be cut or formed by any suitable method either prior to or after formation of the bore 30 with its enlargements, or the grooves 29 can be readily formed by a cross feed cutter of the screw machine which forms the bore 30. It is apparent that the grooves 29 may be formed at any circumferential locationin the terminal portion 27. Thus these grooves 29 may be readily formed without resort to precise indexing of the distributor 25, as has been required heretofore. It is only essential to control the axial dimension of the cylindrical enlargement 33 and the angles of the conical surfaces 32 and 34 in order to control the size and location of each branch passage opening 40a. By predetermining the geometry of the conical surfaces 32, 34, and 39, the spray angle can be readily predetermined, which spray angle will remain constant regardless of variation in volume of fuel and air flow. By vir-tue of the parallel conical walls of the chamber 40, slight variations in depth of the grooves 29 willl not alter the spray angle. In consequence, a simplified method for automatically aligning the openings fitta of chamber 40 with grooves 29 is readily obtained. After formation of the distributor 25, the spray plate 31-39 is pressed iirmly into the endwise opening bore 30a as shown in Figure 3. The distributor, spray plate, `and body 22 are then assembled with the holder 10, 11 to complete the nozzle sub-assembly.

We claim:

1. A fuel-air atomizing nozzle comprising a body having a central opening extending axially therethrough, a substantially cylindrical distributor element received within said opening and having a conical terminal portion extending to the exterior of said body, axially extending fuel passage means between said body and element, said terminal portion having grooves in its conical surface in communication with said fuel passage means and extending to the exterior of said body, air passage means extending axially within said element, branch passages connected with said air passage means and also discharging into said grooves at locations exteriorly of said body, means for connecting said air passage means and fuel passage means with air and fuel supply conduits respectively, and a spray plate portion extending across each groove generally in parallelism with the direction of discharge of the associated branch passage into said groove and blocking said groove at a location adjacent and exteriorly of the location of discharge of said associated branch passage thereinto.

2. A fuel-air atomizing nozzle comprising a body having a central opening extending axially therethrough, a substantially cylindrical distributor element received Within v said opening and having an endwise converging terminal portion extending to the exterior of said body, axially extending fuel passage means between said body and element, said terminal portion having grooves in its outer surface in communication with said fuel passage means and extending to the exterior of said body, air passage means extending axially Within said element, branch passages con nected with said air passage means and also discharging into said grooves at locations exteriorly of said body, means for connecting said air passage means and fuel pas sage means with air and fuel supply conduits respectively, and a spray plate portion extending across each groove generally in parallelism with the direction of discharge of the associated branch passage into said groove and bloclo ing said groove at a location adjacent and exteriorly of the location of discharge of said associated branch passage thereinto.

3. A fuel-air atomizing nozzle comprising a body, a distributor element received within said body and having an endwise converging terminal portion extending to the exterior of said body, axially extending fuel passage means between saidbody and element, said terminal portion having grooves in its outer surface in communication with said fuel passage means and extending to the exterior of said body, air passage means extending axially within said element, branch passages connected with said air passage means and also discharging into said grooves at locations exteriorly. of said body, means for connecting said air passage means and fuel passage means with air and fuel supply conduits respectively, and a spray plate portion extending across each groove generally in parallelismV with the direction of discharge of the associated branch passage into saidgroove and blocking-said groove at a location adjacent andexteriorly ofthe location of discharge of said associated branch passage thereinto.

4. A fuel-air atomizing nozzle comprising a body, a distributor element received within said body and having a terminal portion extending to the exterior of said body, said terminal portion having grooves in its outer surface extending to the exterior of said body, branch passages in said element and discharging into said grooves at locations exteriorly of said body, means for'connecting said grooves and branch passages with separate sources of fuel and air respectively, and a spray plate portion extending across each groove generally in parallelism with the direction of discharge of the associated branch passage into said groove and blocking'said groove at a location adjacent and exteriorly of the location of discharge of said associated branch passage thereinto. Y

5. A fuel-air atomizing nozzle comprising a body, a distributor element vreceivedl within said body and having an endwise converging terminal portion extending to the exterior of said body, said terminal` portion having grooves in its outer surface extending to the exterior of said body, branch passages in said element and discharging into said grooves at locations exteriorly of said body, means for connecting said grooves and branchl passages with separate sources of fuel'and air respectively, vand a spray plate portion extending across each groove generally in parallelism with the direction of discharge of the associated branch passage into said groove `and blockingsaid groove at Ia location adjacenty and exteriorly of the location of discharge of saidv associated branch passagethereinto.

6.. A fuel-air atomizing nozzle comprising a body, a distributor element receivedwithin said body and having a terminal portion extending to the exterior of said body, said terminal portion having grooves in its outer surface extending to the exterior of said body, an endwise opening internal chamber in said terminal portion, said grooves intersecting said chamber at locations exteriorly of said body to provide branch air passages'opening into said grooves at said locations, a spray plate closing the endwise opening of said chamber', said sprayV plate having a portion blocking each groove at a location adjacent and exteriorly of the opening of the associatedV branch passage thereinto, and means internally of said housing for connecting said grooves and chamber with separate sources of fuel and air respectively.

7. A fuel-air atomizing nozzle comprising a body, a distributor element received within said body and having an endwise converging terminal portion extending to the exterior of said body, said terminal portion having grooves in its outer surface extending to the exterior of said body, an endwise Iopening internal chamber in said terminal portion, said groovesv intersecting saidv chamber at locations exteriorly of said body to provide branch air passages opening into said grooves at said locations, said branch air passages being arranged to` discharge air into said grooves transversely thereto, a spray plate closing the endwise opening of said chamber, said spray plate having separate portions extending transversely across said grooves and bloc-king the same at locations adjacent and exteriorly of the locations of discharge of the asso*- ciated branch passages thereinto, and means internally of said housing for connecting said `grooves and cham'- ber with separate sources of fuel andair respectively.

8. A fuel-air atomizing nozzle comprising a body', a `distributor element received within said body and having an endwise converging', terminal portion extendingwto the exterior of said body, an endwise opening internal chamber in said terminal portion, said terminal portion having grooves in its outer surface extending to the exterior of said body, said grooves intersecting said chamber at locations exteriorly of said body to provide branch air passages opening into said grooves at said locations, said branch air passages being arranged to discharge air into said grooves transversely thereto, a spray plate closing the endwise opening of said chamber, said spray plate having separate portions extending transversely across said grooves generally in parallelism with the direction of discharge of the `associated branch passages into said grooves and blocking the same at locations adjacent and exteriorly of the locations of discharge of said associated branch passages thereinto, and means internally of said housing for connecting said grooves and chamber with separate sources of fuel and air respectively.

9. A fuel-air atomizing nozzle comprising a body, a distributor element received within an opening in said body and having an endwise converging terminal portion extending to the exterior of said body, said terminal portion having grooves in its surface extending from within said body to the exterior thereof, a passage in said distributor element opening endwise through said terminal portion, said passage having an annular enlargement adjacent its endwise opening, the inner wall of said enlargement diverging endwise from the axis of said passage at an angle extending transversely of the surface of said terminal portion, a spray plate closing the endwise opening of said passage and having an inner wall spaced from the first-named inner wall and extending substantially in parallelism therewith to provide an annular endwise diverging air chamber in communication with said passage, said grooves intersecting said chamber at locations exteriorly of said body to provide branch air passages opening 'mto said grooves at said locations, said branch air passages being arranged to discharge air into said grooves substantially in parallelism with said walls, said inner wall of said spray plate having portions extending transversely across said grooves and blocking the same, and means internally of said housing for connecting said grooves and passage with sources of fuel and air respectively.

10. A fuel-air atomizing nozzle comprising a body, a distributor element received'within an opening in said body and having an endwise converging terminal portion extending to the exterior of said body, said terminal portion having grooves in its surface extending from within said body to the exterior thereof, a passage in said distributor element opening endwise through said terminal portion, said passage having an annular enlargement adjacent its endwise opening, the inner wall of said enlargement diverging endwise from the axis of said passage at an angle extending approximately normally of the surface of said terminal portion, a spray plate closing the endwise opening of said passage and having an inner wall spaced from the first-named inner wall and extending substantially in parallelism therewith to provide an annular endwise diverging air chamber in communication with said passage, said grooves intersecting said chamber at locations exteriorly of said body to provide branch air passages opening into said grooves at said locations, said branch air passages being arranged to discharge air into said grooves substantially in parallelism with said walls, said inner wall of said spray plate having portions extending transversely across said grooves and blocking the same, and means internally of said housing for connecting said grooves and passage with sources of fuel and air respectively.

11. A fuel-air atomizing nozzle comprising a body, a distributor element received within an opening in said body and having an endwise converging terminal portion extending to the exterior of said body, said terminal portion having grooves in its surface extending from within said body to the exterior thereof, a passage in said distributor element opening endwise through said terminal portion, said passage having an annular endwise diverging inner wall extending transversely of the surface of said terminal portion, a spray plate closing the endwise opening of said passage and having an inner wall spaced from the first-named inner wall and extending substantially in parallelism therewith to provide an annular endwise diverging air chamber in communication with said passage, said grooves intersecting said chamber at locations exteriorly of said body to provide branch air passages opening into said grooves at said locations, said branch air passages being arranged to discharge air into said grooves substantially in parallelism with said walls, said inner wall of said spray plate having portions extending transversely across said grooves and blocking the same, and means internally of said housing for connecting said grooves and passage with sources of fuel and air respectively.

l2. A fuel-air atomizing nozzle comprising a body, a distributor element received within an opening in said body and having an endwise converging terminal portion extending to the exterior of said body, said terminal por- E tion having 4grooves in its surface extending from Within said body to the exterior thereof, a passage in said distributor element opening endwise through said terminal portion, said passage having an annular endwise diverging inner wall extending transversely of the surface of said terminal portion and also having an annular enlargement adjacent the endwise opening of said passage, said enlargement having an outer annular wall spaced endwise from said inner wall and being substantially parallel thereto, a spray plate having an inwardly converging inner wall seated against said outer wall to close the endwise opening of said passage, the second-named inner wall extending inwardly of said body and cooperating with the rstnamed inner wall to provide an annular air chamber in communication with said passage, said grooves intersecting said chamber at locations exteriorly of said body to provide branch air passages opening into said grooves at said locations, said inner wall of said spray plate intersecting said grooves and blocking the same, and means internally of said housing for connecting said grooves and passage with sources of fuel and air respectively.

13. A fuel-air atomizing nozzle comprising a body, a distributor element received within anopening in said body and having an endwise converging conical terminal portion extending to the exterior of said body, said terminal portion having grooves in its surface extending from within said body to the exterior thereof, a control passage in said distributor element opening endwise through said terminal portion, said passage having a conical endwise diverging inner wall extending transversely of the surface of said terminal portion and also having an annular enlargement adjacent the endwise opening of said passage, said enlargement having an outer conical wall spaced endwise from said inner wall and being substantially parallel thereto, a spray plate having an inwardly converging conical inner wall seated against said outer Wall to close the endwise opening of said passage, the second-named inner wall extending inwardly of said body and cooperating with the first-named inner wall to provide an annular' air chamber in communication with said passage, said grooves intersecting said chamber at locations exteriorly of said body to provide branch air passages opening into said grooves at said locations, said inner wall of said spray plate intersecting said grooves blocking the same, and means internally of said housing for connecting said grooves and passage with sources of fuel and air respectively.

14.Y The combination in an atomizing nozzle according to claim 13 wherein said first-named conical inner wall Yextends approximately normally to the conical surface of said terminal portion.

15. The combination in an atomzing nozzle according to claim 12, said distributor element having a cylindrical portion, the first-named opening in said body which receives said distributor having a cylindrical portion of larger diameter than said first-named cylindrical portion and having the latter extending coaxially therein, thereby to provide an annular fuel passage between said distributor and body, said endwise converging terminal portion having a 4generally annular shoulder at its large end of larger diameter than said rst-named cylindrical portion and closing said first-named opening except at said grooves, said grooves extending through said shoulder and communicating with said annular fuel passage to receive fuel therefrom, said annular fuel passage comprising in part 10 said means for connecting said grooves with a source of fuel.

v References Cited in the file of this patent UNITED STATES PATENTS 1,442,814 Long Jan. 23, 1923 2,175,310 Pontius Oct. 10, 1939 2,247,781 Leiman July 1, 1941 2,383,949 Aronson Sept. 4, 1945 2,519,200 Schuman Aug. 15, 1950 2,701,412 Wahlin Feb. 8, 1955 FOREIGN PATENTS 499,641 Belgium Dec. 15, 1950

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