US2973150A - Fuel nozzle for gas turbine engine - Google Patents

Description

Feb. 28, 1961 GQLEC, JR 2,973,150

FUEL NOZZLE FOR GAS TURBINE ENGINE Filed May 12, 1958 INVENTOR. 72477746 d/ec,

United States Patent v FUEL NOZZLE F OR GAS TURBINE ENGINE Filed May 12, 1958,:Sel'. No. 734,673

6 Claims. (Cl. 239-425) This invention relates to an air-fuel atomizing nozzle adapted to be used with a gas turbine liquid fuel control system.

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

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 is 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 which 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 flow 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 of the nozzle assembly. The air 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 is thereby atomized by the air externally of the nozzle rather thanin 'an internal mixing chamber or in internal nozzle passages. The resulting spray or distribution pattern is comprised of fuel particles which are more finely dispersed than the pattern obtainable with conventional nozzles ate. comparable air pressure and air flow.

Important objects of the present invention :are to provide an improved atomizing nozzle of the above type which is comparatively simple and economical to manufacture and which .is characterizedby improved efficiency and fuel-air mixing properties, such that the nozzle operates effectively at comparatively low fuel and air pressures and low air mass flow with respect to conventional nozzles.

Another objectis to provide a new and improved fuel- ;air atomizing nozzle for use with the combustion chamber of a liquid fuel combustion apparatus, which is adapted tflprovide a completely atomized spray or fuelair-distribution pattern throughout a wide range of controlled variations in the rate of fuel consumption.

Another and morespecific Object of the present inven- 7 2,973,150 Paten d F ice ,2 tion is to provide an improved fuel-air atomizing nozzle structure having a cylindrical distributor element received within a nozzle .body. The distributor element is provided with an endwise converging conical terminal portion which'extends to the exterior of the body. A plurality'of fuel passage grooves extendin theouter surface of the terminal portion from within the body to its exterior and are intersected at locations exteriorly of the body by branch air passages in the distributor element which extend substantially normally to the grooves and communicate with a central air chamber within the distributor element. 'The air chamber and fuel passage grooves are connected within the nozzle structure to sources of fuel and air respectively under pressure. In addition, a spray plate is prov idedwhich extends transversely across the grooves in parallelism with the direction of discharge -of air into the grooves from the branch a'ir passages and blocks the grooves at locations adjacent and endwise of their intersections with the branch air passages. The aforesaid aiichamber is located coaxially within the terminal portion and opens endwise to receive the spray plate by a press fit therein. By virtue of the foregoing structure, major simplifications and economies in fabrication and assembly are enabled and anoptimum atomization and apreferred spraypattern are achieved.

Among the problems involved in the manufacture of fuel-airatomizing nozzles of the foregoing type are the provision of a suitable seal between the separate fuel and air passages within the nozzle structure, while at the same time assuring proper positioning of the distributor element and its branch air passages with'respect to the nozzle body. These problems arise in part because the nozzle structure is subject to temperature variations ranging between approximately 0 F. and 700 F., and the distributor element and nozzle body are preferably fabricated from metals having different coefficients of thermal expansion. Conventionalrubber-type seals are not capable of withstanding either the temperature extremes or the deteriorating action of the fuel.

Another important object of the invention is to provide an improved nozzle structure including resilient sealingrneans effecting the desired sealing action between the fuel and air passages within the nozzle structure while at the same time enabling differential thermal expansion between the nozzle elements of different materials.

Still another object is to provide a nozzle structure as described wherein the radially outer periphery of the endwise converging conical terminal portion of the distributor is yieldingly urged into seated engagement the mating interior conical surface of an annular flange of the nozzle body. The flange and terminal portion are dimensioned so that the openings of the branch air passages of the distributor element into the fuel passage grooves of the terminal portion are located immediately forward or exteriorly of the aforesaid flange of the nozzle body. The end of the distributor element opposite the terminal portion is reduced in diameter to provide a seal retaining shoulder, the reduced end being slidably sleeved Within an air passage bore'suitably connected with said air source. Also an axial air passage extends into the reduced end of the distributor element to the latters aforesaid central air chamber to supply pressurized air .thereto. In order to urge the terminal portion of the distributor element yieldingly endwise into seating engage ment with the mating body flange, a conical washer type spring steel seal extends. around the distributor element under tension between the aforesaid seal retaining shoulder and an annular internal seal retaining shoulder o f the nozzle body of larger diameter than the first-named seal retainingshoulder. By virtue of the tension in the washer-seal, .the latter makes sealinguengagement with the two seal retaining shoulders, thereby to provide an effective fluid seal for the sliding engagement between the reduced inner end of the distributor and the nozzle body, while at the same time urging the terminal portion of the distributor element into its seated engagement with the conical surface of the aforesaid body flange.

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.

Figure 1 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 a fragmentary elevational view from the right end of Figure 1.

Figure 3 is an enlarged longitudinal mid-section showing the distributor andsprayvplate removed from the nozzle body. t

Figure 4 is an enlarged longitudinal mid-sectional view similar to the sectional portion of Figure 1, showing details of the seal. 7 4 I 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 thephraseology or terminology employed herein is for the purpose of description and not of limitation. Referring to Figure l, a nozzle structure embodying the present invention is illustrated by way of example comprising a two part nozzle body including a T-shaped holder having a cylindrical portion 10 and an integral transverse bracket 11. The body 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, thebore 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 within the body portion 10 into bracket 11: and opening at a threaded socket 17 suitable for at tachment with a source of fuel under pressure. The shoulder between the portions 14 and is rounded at, 18 to provide a seal retaining shoulder or seat for an annular conical hardened steel washer-type spring seal 19, Figure 4, which may comprise a Belleville washer. v

Endwise of the enlargement 15, the bore of the cylindrical body portion 10 is reduced and threaded at 20 to receive the reduced threaded end 21 of a second or forward cylindrical nozzle body portion 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 annular flange 24 having an inner conical endwise converging surface. Extending coaxially within the cylindrical opening 23 is a cylindrical distributor element 25 having a reduced rear end portion 26 closely fitting in axially sliding relationship within bore 12 rearwardly of the enlargement 14. Within the latter enlargement, the outer wall of the distributor 25 enlarges conically at an angle slightly less than the conical angle of seal 19, Figure 4, to provide a second annular seal retaining shoulder 25a or seat for the inner periphery of spring seal 19. The seal 19 is under tension yieldingly engaging theshoulders 18 and 25a 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 providermeans to 'compensatefor differential thermal expansion'between the nozzle elements. The portion of opening 23 around the distributor 25 comprises an annular fuel passage in iaovsneo communication with passages 15, 16 to receive fuel therefrom and will be referred to hereinafter as fuel passage 23.

In a preferred construction, the body portions 10 and 22 are preferably of a non-corrosive metal such as stainless steel and are suitably secured together as a unitary structure, as for example by brazing or by the threaded connection shown. In the latter instance a conventional annular sealing washer 22a is employed between the confronting annular surfaces of the body portions 10 and 22. To facilitate machining, the distributor 25 is preferably formed of brass into which the inner periphery of the harder sealing washer 19 tends to embed to complete an annular fluid-tight seal around the distributor 25 adjacent the base of the shoulder 25a.

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 portion 22 and extends to the exterior of the latter. 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. For larger en- 'gines, 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 equally spaced 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 ooaxially through the cylindrical distributor 25 is an air passage or bore 30 having an enlarged forward portion 30a adapted to receive the stem 31 of a spray plate described below. The stem 31 is of elongated sec tion having opposite cylindrical edge portions 31a pressfitted snugly into bore portion 30a and having opposite flattened side portions 31b provided to enable free passage of air past stem 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 3. 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 there around 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 3.0a. Also as illustrated in FigureS, 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 portion 22, Figure l. The peripheral portions of the conical spray plate surface 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 1S 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 40:: 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 grioves and effects a substantially endwise diverging air-fuel atomized 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 the distributor element 25 with its conical endwise enlarging chamber portions 32, 33, and 34 can be readily formed by automatic screw machines. The grooves 29 are formed by a cross feed cutter of the screw machine which forms the portions 30, 32-34, or are cut either after or prior to formation of the bore 30 with its enlargements. It is apparent that the grooves 29 may be formed at any circumferential location in 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 predetennining 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 virtue of the parallel conical walls of the chamber 40, slight variations in depth of the grooves 29 will not alter the spray angle. In consequence, a simplified methodfor automatically aligning the openings 40a of chamber 40 with grooves 29 is readily obtained. After formation of the distributor 25, the spray plate 31-39 is pressed firmly into the endwise opening bore 30a as shown in Figure 3. The distributor- 25, seal 19, spray plate 39, and body portion 22 are then assembled with the body to complete the nozzle sub-assembly.

It is apparent that the spring washer seal 19 enables appreciable variation in the amount that the "body portions 10 and 22 can be tightened together, and correspondingly the extent of compression or flattening of seal 22a. It is contemplated in a nozzle structure of the type disclosed that the extension 21 will be moved axially into the opening 20 until the unstressed conical seal 19 abuts the shoulders 18 and 25a. Thereafter the body portions 10 and 22 are tightened together against the tension of washer seal 19 and washer 22a, if the latter is employed, for a total axial movement of between a few to approximately twenty thousandths of an inch. Thus the washer seal 19 is stressed to hold the conical terminal portion 27 in seated engagement with the body flange 24 while at the same time enabling relative thermal expansion and contraction of the distributor 25 with respect to the body 10, 22 and sealing the sliding engagement of the distributor extension 26 within the bore 12. Accordingly appreciable tolerance is permitted in the relative assembled positions of the body portions 10 and 22 without in any way interfering with alignment of the openings 40a with respect to the end or exterior surface of flange 24, which latter alignment must be maintained comparatively accurately to assure proper functioning of the nozzle.

I claim:

1. In a fuel-air atomizing nozzle having a discharge end, a nozzle body having a first fluid passage therein, a distributor element having an end portion slidably received in said first passage and having a fluid passage opening into said first passage to comprise a continuation thereof extending toward said discharge end, said body having a portion abutting said distributor element to limit sliding movement of the latter in one direction, said distributor element having an annular seal retaining shoulder enlarging conically in said direction at a location downstream of said end portion, a second :fiuid passage extending toward said discharge end .in the space between the outer periphery of said distributor element and the wall of said first passage, separateconduit means in communication with said passages respectively to supply fuel and air thereto, and means effecting a fluid seal between said first and second passages comprising a conical spring washer seal around said distributor element and enlarging in said direction in the assembled position at an angle greater than the conical angle of enlargement of said retaining shoulder, the inner periphery of said washer seal having a sharp edge sealingly engaging said retaining shoulder under tension and the outer portion of said washer seal sealingly engaging said body under tension at locations upstream of said second passage, said washer seal urging said distributor element yieldingly in .said direction with respect to said body.

2. In a fuel-air atomizing nozzle having a discharge end, a nozzle body having a first fluid passage, therein, a distributor element having an end portion slidably received in said first passage and having a fluid passage opening into said first passage to comprise a continuation thereof extending toward said discharge end,.said body having a portion abutting said distributor element to limit sliding movement of the latter in one direction, said distributor element having an annular seal retaining shoulder enlarging conically in said direction at a location downstream of said end portion, a second fluid passage extending toward said discharge end in the space between the outer periphery of said distributor element and the wall of said first passage, separate conduit means in communication with said passages respectively tosupply fuel and air thereto, means elfecting a fluid seal between said first and second passages comprising a conical spring washer seal around said distributor element and enlarging in said direction in the assembled position at an angle greater than the conical angle of enlargement of said retaining shoulder, the inner-periphery of said washer seal having a sharp edge sealingly engaging said retaining shoulder under tension and. the outer portion of said washer seal sealingly engaging an annular shoulder of said body under tension at locations upstream of said second passage, said washer seal urging said distributor element yieldingly in said one direction with respect vto said body, said distributor element being of softer material than said washer seal and body and having a different coeflicient of thermal expansion than said body, and said sharp edge being embedded'int-he material of said retaining shoulder. Y v w 3. In a fuel-air atomizing nozzle, a body having a distnbutor receiving chamber therein, a distributor element having a tubular stem slidably supported in said chamber to enable relative thermal expansion and contraction between said stem and body and also having portions abutting portions of said body in fixed spatial relationship and cooperating therewith to define fuel and air admixing ducts, the bore of said stem communicating with a first portion of said chamber to comprise a first fluid passage in communication with said ducts, a second portion of said chamber around the outer periphery of said stem comprising a second fluid passage in communication with said ducts, said distributor element having a peripheral seal retaining shoulder extending therearound at a location downstream of said first portion of said chamber, separate conduit means in communication with said first and second passages respectively to supply fuel and air thereto, and means elfecting a fluid seal between said first and second passages comprising a washer type spring seal extending around said distributor element, the inner periphery of said spring seal sealingly engaging said shoulder and the outer portion of said spring seal sealingly engaging an annular portion of said body under tension yieldingly enabling said relative thermal expansion and contraction while maintaining said fixed spatial relationship between the abutting portions of said body and-distributor element.

Y 4. In a fuel-air atomizing nozzle having a discharge end, a body having a distributor receiving chamber therein, a tubular distributor element having an inner end slidably supported in said chamber to enable relative thermal expansion and contraction between said inner end and body, the bore of said distributor element opening at said inner end into one portion of said chamber and cooperating therewith to comprise a first fluid passage, said body having an end flange abutting outer end portions of said distributor element adjacent said discharge end in fixed spatial relationship therewith and limiting movement of said outer end with respect to said body in the direction toward said discharge end, said distributor element having a peripherial seal retaining shoulder located downstream of said inner end, a second portion of said chamber around the outer periphery of said distributor element comprising a second fluid passage said first and second passages being in communication with separate intersecting ducts respectively defined by said body and distributor element adjacent said discharge end, separate conduit means in communication with said first and second passages respectively to supply fuel and air thereto, and means effecting a fluid seal between said first and second passages comprising a washer type spring seal extending around said distributor element, the inner periphery of saidspring seal sealingly engaging said shoulder and the outer portion of said spring seal sealingly engaging an annular portion of said body under tension urging said distributor element yieldingly toward said discharge end to maintain said fixed spatial relationship between said distributor element and body adjacent said discharge end and enabling said relative thermal expansion and contraction at said inner end.

5. In a fuel-air atomizing nozzle, a nozzle body having a distributor receiving chamber therein, a distributor element slidably received in said chamber to enable relative thermal expansion and contraction between said body and portions of said distributor element and also having a duct opening-into one part of said chamber and cooperating therewith to comprise a first fiuid'passage, said body having a portion in abutment with said dis tributor element at a location downstream of said one part of said chamber, a second part of said chamber spaced from the outer periphery of said distributor element comprising a second fluid passage, branch fluid passages in said distributor element intersecting said sec- 0nd fluid passage in fixed spatial relationship adjacent said location, separate conduit means in communication with said first and second passages respectively to supply fuel and air thereto, and means eflecting a fluid seal between said first and second passages comprising a washer-type spring seal around said distributor element, the inner and outer portions of said washer-type seal sealingly engaging said distributor element and said body respectively under tension maintaining the aforesaid abutment between said body and distributor element while yieldingly enabling said relative thermal expansion and contraction between said distributor element and body.

6. In a fuel-air atomizing, a nozzle body, a distributor element having sliding movement within said body to enable relative thermal expansion and contraction between said body and portions of said distributor element, said distributor element also having portions in abutment with said body to limit said sliding movement in one direction, first fluid passage means defined by said body and the exterior of said distributor element, second fluid passage means extending in said distributor element, branch duct means defined at least in part by said distributor element and intersecting said second fluid passage means adjacent the abutment between said distributor element and body, separate conduit means in communication with said first and second fluid passage means respectively to supply fuel and air thereto, and means eifecting a fluid seal between said first and second fluid passage means comprising a spring seal around said distributor element, said spring seal having inner and outer portions sealingly engaging said distributor element and said body respectively under tension maintaining the aforesaid abutment between said body and distributor element while yieldingly enabling said relative thermal expansion and contraction between said distributor element and body.

References Cited in the file of this patent I UNITED STATES PATENTS 1,442,814 Long Jan. 23, 1923 1,799,551 Forney Apr. 7, 1931 2,090,150 Pontius Aug. 17, 1937 2,308,475 Fawkes Jan. 12, 1943 2,519,200 Schumann Aug. 15, 1950 2,574,879 Lundberg et al Nov. 13, 1951 2,776,851 Heinrich Ian. 8, 1957 FOREIGN PATENTS 545,275 Great Britain May 18, 1942 UNITED STATES PATENT OFFICE CERTIFICATION OF CORECTION Patent No. 2,973,155) Fehruary 28,' 1961 Thomas GoIec- Jr,

It is hereby certified that error eppears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 2, for "grim/es" reed grooves column 8 line 123 for "atomizing read atomlzlng nozzle,

Signed and sealed this 22nd day" of August F961. I

(SEAL) I Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting ()fficer Commissioner of Patents I

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