US20090255260A1 - Venturi - Google Patents

Abstract

A venturi is disclosed, the venturi comprising a mixing cavity surrounded circumferentially by an annular venturi wall, and a swirler having a plurality of vanes arranged circumferentially around a swirler axis, wherein the swirler and the annular venturi wall have a unitary construction. In another exemplary embodiment the venturi comprises an annular venturi wall, a swirler located at an axially forward portion of the venturi, the swirler having a plurality of vanes arranged circumferentially around a swirler axis, and a heat shield located axially aft from the swirler, wherein the annular venturi wall, the swirler and the heat shield have a unitary construction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This Application claims priority to U.S. Provisional Application Ser. No. 61/044,116, filed Apr. 11, 2008, which is herein incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
• This invention relates generally to venturis, and more specifically to unitary venturis having swirlers for promoting mixing of fuel and air and a heat shield for protection from combustion heat in fuel nozzles used in gas turbine engines.
• Turbine engines typically include a plurality of fuel nozzles for supplying fuel to the combustor in the engine. The fuel is introduced at the front end of a burner in a highly atomized spray from a fuel nozzle. Compressed air flows around the fuel nozzle and mixes with the fuel to form a fuel-air mixture, which is ignited by the burner. Because of limited fuel pressure availability and a wide range of required fuel flow, many fuel injectors include pilot and main nozzles, with only the pilot nozzles being used during start-up, and both nozzles being used during higher power operation. The flow to the main nozzles is reduced or stopped during start-up and lower power operation. Such injectors can be more efficient and cleaner-burning than single nozzle fuel injectors, as the fuel flow can be more accurately controlled and the fuel spray more accurately directed for the particular combustor requirement. The pilot and main nozzles can be contained within the same nozzle assembly or can be supported in separate nozzle assemblies. These dual nozzle fuel injectors can also be constructed to allow further control of the fuel for dual combustors, providing even greater fuel efficiency and reduction of harmful emissions. The temperature of the ignited fuel-air mixture can reach an excess of 3500° F. (1920° C.). It is therefore important that the fuel supply conduits, flow passages and distribution systems are substantially leak free and are protected from the flames and heat.
• Various governmental regulatory bodies have established emission limits for acceptable levels of unburned hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), which have been identified as the primary contributors to the generation of undesirable atmospheric conditions. Therefore, different combustor designs have been developed to meet those criteria. For example, one way in which the problem of minimizing the emission of undesirable gas turbine engine combustion products has been attacked is the provision of staged combustion. In that arrangement, a combustor is provided in which a first stage burner is utilized for low speed and low power conditions to more closely control the character of the combustion products. A combination of first stage and second stage burners is provided for higher power outlet conditions while attempting to maintain the combustion products within the emissions limits. It will be appreciated that balancing the operation of the first and second stage burners to allow efficient thermal operation of the engine, while simultaneously minimizing the production of undesirable combustion products, is difficult to achieve. In that regard, operating at low combustion temperatures to lower the emissions of NOx, can also result in incomplete or partially incomplete combustion, which can lead to the production of excessive amounts of HC and CO, in addition to producing lower power output and lower thermal efficiency. High combustion temperature, on the other hand, although improving thermal efficiency and lowering the amount of HC and CO, often results in a higher output of NOx. In the art, one of the ways in which production of undesirable combustion product components in gas turbine engine combustors is minimized over the engine operating regime is by using a staged combustion system using primary and secondary fuel injection ports.
• Another way that has been proposed to minimize the production of those undesirable combustion product components is to provide for more effective intermixing of the injected fuel and the combustion air. In that regard, numerous swirlers, mixer designs and venturi designs have been proposed over the years to improve the mixing of the fuel and air. In this way, burning occurs uniformly over the entire mixture and reduces the level of HC and CO that result from incomplete combustion. However, there is still a need to minimize the production of undesirable combustion products over a wide range of engine operation conditions. Better mixing of fuel and air in fuel nozzles using swirlers in a venturi designed to promote such mixing will be useful in reducing undesirable combustion emissions.
• Over time, continued exposure to high temperatures during turbine engine operations may induce thermal gradients and stresses in the conduits and fuel nozzles which may damage the conduits or fuel nozzle and may adversely affect their operation. For example, thermal gradients may cause fuel flow reductions in the conduits and may lead to excessive fuel maldistribution within the turbine engine. Exposure of fuel flowing through the conduits and orifices in a fuel nozzle to high temperatures may lead to coking of the fuel and lead to blockages and non-uniform flow. To provide low emissions, modern fuel nozzles require numerous, complicated internal air and fuel circuits to create multiple, separate flame zones. Fuel circuits may require heat shields from the internal air to prevent coking, and certain tip areas may have to be cooled and shielded from combustion gases. Additional features may have to be provided in the heat shields to promote heat transfer and cooling. Furthermore, over time, continued operation with damaged fuel nozzles may result in decreased turbine efficiency, turbine component distress, and/or reduced engine exhaust gas temperature margin.
• Improving the life cycle of fuel nozzles installed within the turbine engine may extend the longevity of the turbine engine. Known fuel nozzles include a delivery system, a mixing system, and a support system. The delivery system comprising conduits for transporting fluids delivers fuel to the turbine engine and is supported, and is shielded within the turbine engine, by the support system. More specifically, known support systems surround the delivery system, and as such are subjected to higher temperatures and have higher operating temperatures than delivery systems which are cooled by fluid flowing through the fuel nozzle. It may be possible to reduce the thermal stresses in the conduits and fuel nozzles by configuring their external and internal contours and thicknesses.
• Air-fuel mixers have swirler assemblies that swirl the air passing through them to promote mixing of air with fuel prior to combustion. The swirler assemblies used in the combustors may be complex structures having axial, radial or conical swirlers or a combination of them. In the past, conventional manufacturing methods have been used to fabricate mixers having separate venturi and swirler components that are assembled or joined together using known methods to form assemblies. For example, in some mixers with complex vanes, individual vanes are first machined and then brazed into an assembly. Investment casting methods have been used in the past in producing some combustor swirlers. Other swirlers and venturis have been machined from raw stock. Electro-discharge machining (EDM) has been used as a means of machining the vanes in conventional fuel nozzle components.
• Conventional gas turbine engine components such as, for example, fuel nozzles and their associated swirlers, conduits, distribution systems, venturis and mixing systems are generally expensive to fabricate and/or repair because the conventional fuel nozzle designs having complex swirlers, conduits and distribution circuits and venturis for transporting, distributing and mixing fuel with air include a complex assembly and joining of more than thirty components. More specifically, the use of braze joints can increase the time needed to fabricate such components and can also complicate the fabrication process for any of several reasons, including: the need for an adequate region to allow for braze alloy placement; the need for minimizing unwanted braze alloy flow; the need for an acceptable inspection technique to verify braze quality; and, the necessity of having several braze alloys available in order to prevent the re-melting of previous braze joints. Moreover, numerous braze joints may result in several braze runs, which may weaken the parent material of the component. The presence of numerous braze joints can undesirably increase the weight and manufacturing cost of the component.
• Accordingly, it would be desirable to have a venturi having complex geometries for mixing fuel and air in fuel nozzles while protecting the structures from heat for reducing undesirable effects from thermal exposure described earlier. It is desirable to have venturis having integral heat shields having features that promote heat exchange and cooling of structures. It is desirable to have a venturi having complex geometries with a unitary construction to reduce the cost and for ease of assembly as well as providing protection from adverse thermal environment. It is desirable to have a method of manufacturing to provide a unitary construction for a venturi having complex three-dimensional geometries, such as, for example, a venturi with swirler and heat shield systems for use in fuel nozzles.
BRIEF DESCRIPTION OF THE INVENTION
• The above-mentioned need or needs may be met by exemplary embodiments which provide a venturi comprising a mixing cavity surrounded circumferentially by an annular venturi wall, and a swirler having a plurality of vanes arranged circumferentially around a swirler axis, wherein the swirler and the annular venturi wall have a unitary construction.
• In another exemplary embodiment, the venturi comprises an annular venturi wall, a swirler located at an axially forward portion of the venturi, the swirler having a plurality of vanes arranged circumferentially around a swirler axis, and a heat shield located axially aft from the swirler, wherein the annular venturi wall, the swirler and the heat shield have a unitary construction.
BRIEF DESCRIPTION OF THE DRAWINGS
• The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding part of the specification. The invention, however, may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which:
• FIG. 1 is a diagrammatic view of a high bypass turbofan gas turbine engine comprising an exemplary fuel nozzle having a venturi according to an exemplary embodiment of the present invention.
• FIG. 2 is an isometric view of an exemplary fuel nozzle having a venturi according to an exemplary embodiment of the present invention.
• FIG. 3 is an axial cross-sectional view of an exemplary nozzle tip assembly of the exemplary fuel nozzle shown inFIG. 2.
• FIG. 4 is an isometric view of a venturi according to an exemplary embodiment of the present invention.
• FIG. 5 is an axial cross sectional view of the exemplary venturi shown inFIG. 4.
• FIG. 6 is another isometric view of the exemplary venturi shown inFIG. 4, with a portion of the venturi sectioned away.
• FIG. 7 is a top plan view of a venturi shown inFIG. 6 with a portion of the venturi sectioned away.
• FIG. 8 is an isometric view of a venturi according to an alternative exemplary embodiment of the present invention with a portion sectioned away.
• FIG. 9 is a flow chart showing an exemplary embodiment of a method for fabricating a unitary venturi.
DETAILED DESCRIPTION OF THE INVENTION
• Referring now to the drawings in detail, wherein identical numerals indicate the same elements throughout the figures,FIG. 1 shows in diagrammatic form an exemplary gas turbine engine10 (high bypass type) incorporating anexemplary fuel nozzle100 having an exemplary embodiment of a venturi (such asitems500, shown in the figures and described herein) used for promoting mixing of air with the fuel in thefuel nozzle100. The exemplarygas turbine engine10 has anaxial centerline axis12 therethrough for reference purposes.Engine10 preferably includes a core gas turbine engine generally identified bynumeral14 and afan section16 positioned upstream thereof.Core engine14 typically includes a generally tubularouter casing18 that defines anannular inlet20.Outer casing18 further encloses and supports abooster22 for raising the pressure of the air that enterscore engine14 to a first pressure level. A high pressure, multi-stage, axial-flow compressor24 receives pressurized air frombooster22 and further increases the pressure of the air. The pressurized air flows to acombustor26, where fuel is injected into the pressurized air stream and ignited to raise the temperature and energy level of the pressurized air. The high energy combustion products flow fromcombustor26 to a first (high pressure)turbine28 for driving thehigh pressure compressor24 through a first (high pressure) driveshaft30, and then to a second (low pressure)turbine32 for drivingbooster22 andfan section16 through a second (low pressure) driveshaft34 that is coaxial withfirst drive shaft30. After driving each ofturbines28 and32, the combustion products leavecore engine14 through anexhaust nozzle36 to provide at least a portion of the jet propulsive thrust of theengine10.
• Fan section16 includes a rotatable, axial-flow fan rotor38 that is surrounded by anannular fan casing40. It will be appreciated thatfan casing40 is supported fromcore engine14 by a plurality of substantially radially-extending, circumferentially-spaced outlet guide vanes42. In this way,fan casing40 enclosesfan rotor38 andfan rotor blades44.Downstream section46 offan casing40 extends over an outer portion ofcore engine14 to define a secondary, or bypass,airflow conduit48 that provides additional jet propulsive thrust.
• From a flow standpoint, it will be appreciated that an initial airflow, represented byarrow50, entersgas turbine engine10 through aninlet52 tofan casing40. Air flow50 passes throughfan blades44 and splits into a first compressed air flow (represented by arrow54) that moves throughconduit48 and a second compressed air flow (represented by arrow56) which entersbooster22.
• The pressure of secondcompressed air flow56 is increased and entershigh pressure compressor24, as represented byarrow58. After mixing with fuel and being combusted incombustor26,combustion products60exit combustor26 and flow throughfirst turbine28.Combustion products60 then flow throughsecond turbine32 andexit exhaust nozzle36 to provide at least a portion of the thrust forgas turbine engine10.
• Thecombustor26 includes anannular combustion chamber62 that is coaxial withlongitudinal axis12, as well as aninlet64 and anoutlet66. As noted above,combustor26 receives an annular stream of pressurized air from a high pressurecompressor discharge outlet69. A portion of this compressor discharge air (“CDP” air) identified by the numeral190 in the figures herein, flows into a mixer (not shown). Fuel is injected from a fuel nozzle tip assembly to mix with the air and form a fuel-air mixture that is provided tocombustion chamber62 for combustion. Ignition of the fuel-air mixture is accomplished by a suitable igniter, and the resultingcombustion gases60 flow in an axial direction toward and into an annular, firststage turbine nozzle72.Nozzle72 is defined by an annular flow channel that includes a plurality of radially-extending, circumferentially-spacednozzle vanes74 that turn the gases so that they flow angularly and impinge upon the first stage turbine blades offirst turbine28. As shown inFIG. 1,first turbine28 preferably rotateshigh pressure compressor24 viafirst drive shaft30.Low pressure turbine32 preferably drivesbooster24 andfan rotor38 viasecond drive shaft34.
• Combustion chamber62 is housed within engineouter casing18. Fuel is supplied into the combustion chamber byfuel nozzles100, such as for example shown inFIGS. 2 and 3. Liquid fuel is transported through conduits within astem103, such as, for example, shown inFIG. 3, to the fuelnozzle tip assembly68. Conduits that have a unitary construction may be used for transporting the liquid fuel into the fuelnozzle tip assembly68 of thefuel nozzles100. The fuel supply conduits, may be located within thestem103 and coupled to afuel distributor tip180. Pilot fuel and main fuel are sprayed into thecombustor26 by fuelnozzle tip assemblies68, such as for example, shown inFIGS. 2 and 3. During operation of the turbine engine, initially, pilot fuel is supplied through a pilot fuel flow passage, such as, for example, shown asitems102,104 inFIG. 3, during pre-determined engine operation conditions, such as during startup and idle operations. The pilot fuel is discharged fromfuel distributor tip180 through thepilot fuel outlet162. When additional power is demanded, main fuel is supplied through main fuel passageways105 (seeFIG. 3) and the main fuel is sprayed using themain fuel outlets165.
• FIGS. 3-7 show an exemplary embodiment of the present invention of aunitary venturi500.FIGS. 2 and 3 show an exemplary embodiment of afuel nozzle100 andfuel nozzle tip68 having the exemplaryunitary venturi500.FIG. 8 shows an alternative exemplary embodiment of aunitary venturi600. The term “unitary” is used in this application to denote that the associated component, such as theventuri500,600 described herein, is made as a single piece during manufacturing. Thus, a unitary component has a monolithic construction for the component.FIG. 4 shows an isometric view of aunitary venturi500 according to an exemplary embodiment of the present invention. Theexemplary venturis500,600 shown inFIGS. 3-8 include a circumferential array ofvanes508 that impart a swirling motion to the air passing therethrough to enhance fuel-air mixing within the fuel nozzle. Theexemplary venturis500,600 shown inFIGS. 3-8 may have a unitary construction made using methods described subsequently herein.
• Referring toFIGS. 2 and 3,fuel distributor tip180 extends from thestem103 such thatmain fuel passageways105 and thepilot fuel passageways102,104 in theunitary distributor ring171 are coupled in flow communication corresponding fuel supply conduits contained within thestem103.Main fuel passageways105 are coupled in flow communication to main fuel circuits defined withinunitary distributor ring171.Primary pilot passage102 andsecondary pilot passage104 are coupled in flow communication with corresponding pilot injectors positioned radially inward within a fuel nozzle (seeFIG. 3). It will be apparent to those skilled in the art that although thedistributor ring171 has been described herein above as a unitary conduit (i.e., having a unitary construction), it is possible to use adistributor ring171 having other suitable manufacturing constructs using methods known in the art. Theunitary distributor ring171 is attached to thestem103 using conventional attachment means such as brazing. Alternatively, theunitary distributor ring171 and thestem103 may be made by rapid manufacturing methods such as for example, direct laser metal sintering, described herein.
• FIG. 3 shows an axial cross section of an exemplaryfuel nozzle tip68 having an exemplary embodiment of the present invention of aunitary venturi500. The exemplaryfuel nozzle tip68 shown inFIG. 3 has two pilot fuel flow passages, referred to herein as a primarypilot flow passage102 and a secondarypilot flow passage104. Referring toFIG. 3, the fuel from the primarypilot flow passage102 exits the fuel nozzle through a primarypilot fuel injector163 and the fuel from the secondarypilot flow passage104 exits the fuel nozzle through a secondarypilot fuel injector167. The primarypilot flow passage102 in thedistributor ring171 is in flow communication with a corresponding pilot primary passage in the supply conduit contained within the stem103 (seeFIG. 2). Similarly, the secondarypilot flow passage104 in thedistributor ring171 is in flow communication with a corresponding pilot secondary passage in the supply conduit contained within thestem103.
• As described previously, fuel nozzles, such as those used in gas turbine engines, are subject to high temperatures. Such exposure to high temperatures may, in some cases, result in fuel coking and blockage in the fuel passages, such as for example, theexit passage164. One way to mitigate the fuel coking and/or blockage in thedistributor ring171 is by using heat shields to protect the passages (such asitems102,104,105 shown inFIG. 3) from the adverse thermal environment. In the exemplary embodiment shown inFIG. 3, thefuel conduits102,104,105 are protected bygaps116 and heat shields that at least partially surround these conduits. Thegap116 provides protection to the fuel passages by providing insulation from adverse thermal environment. In the exemplary embodiment shown, theinsulation gaps116 have widths between about 0.015 inches and 0.025 inches. The heat shields, such as those described herein, can be made from any suitable material with ability to withstand high temperature, such as, for example, cobalt based alloys and nickel based alloys commonly used in gas turbine engines. In exemplary embodiment shown inFIG. 3, thedistributor ring171 has a unitary construction wherein thedistributor ring171, theflow passages102,104,105, thefuel outlets165, the heat shields and thegaps116 are formed such that they have a monolithic construction.
• FIG. 4 shows an isometric view of aswirler500 according to an exemplary embodiment of the present invention andFIG. 5 shows an axial cross sectional view of the exemplary venturi shown inFIG. 4. Referring toFIG. 5, theexemplary venturi500 comprises anannular venturi wall502 around theswirler axis11 that forms a mixingcavity550 wherein a portion of air and fuel are mixed. The annular venturi wall may have any suitable shape in the axial and circumferential directions. A conical shape, such as shown for example inFIG. 5, that allows for an expansion of the air/fuel mixture in the axially forward direction is preferred. Theexemplary venturi500 shown inFIG. 5 has an axiallyforward portion509 having an axiallyforward end501, and an axiallyaft portion511 having an axiallyaft end519. The axiallyforward portion509 has a generally cylindrical exterior shape (seeFIG. 6) wherein theannular venturi wall502 is generally cylindrical around theswirler axis11. Theventuri wall502 has at least onegroove504 located on its radially exterior side capable of receiving a brazing material during assembly of anozzle tip assembly68. In the exemplary embodiment shown inFIGS. 5 and 6, twoannular grooves504 are shown, onegroove504 near the axiallyforward end501 and anothergroove504 near an intermediate location between the axiallyforward end501 and the axiallyaft end519. Thegrooves504 may be formed using conventional machining methods. Alternatively, thegrooves504 may be formed integrally when theventuri wall502 is formed, such as, for example, using the methods of manufacturing aunitary venturi500 as described subsequently herein. In another aspect of the present invention, theventuri500 comprises a lip518 (alternatively referred to herein as a drip-lip518) located at the axiallyaft end519 of theventuri wall502. The drip-lip518 has a geometry (seeFIG. 5) such that liquid fuel particles that flow along theinner surface503 of theventuri wall502 separate from thewall502 and continue to flow axially aft. The drip-lip518 thus serves to prevent the fuel from flowing radially outwards along the venturi walls at exit.
• As shown inFIG. 5, the exemplary embodiment ofventuri500 comprises anannular splitter530 having anannular splitter wall532 located radially inward from theannular venturi wall502 and coaxially located with it around the swirler axis11. The radiallyouter surface533 of thesplitter530 and the radiallyinner surface503 of theventuri wall502 form an annular swirled-air passage534. The forward portion of thesplitter wall532 has arecess535 that facilitates interfacing theventuri500 with an adjacent component, such as for example, shown asitem208 inFIG. 2, during assembly of a fuelnozzle tip assembly68. Thesplitter530 has asplitter cavity560 wherein a portion of theair190 mixes with the fuel ejected from thepilot outlets162,164 (seeFIG. 2).
• The exemplary embodiment of theventuri500 shown inFIGS. 5,6 and7 comprises aswirler510. Although theswirler510 is shown inFIG. 5 as being located at the axiallyforward portion509 of theventuri500, in other alternative embodiments of the present invention, it may be located at other axial locations within theventuri500. Theswirler510 comprises a plurality ofvanes508 that extend radially inward between theventuri wall502 and theannular splitter530. The plurality ofvanes508 are arranged in the circumferential direction around theswirler axis11.
• Referring toFIGS. 5 and 6, in the exemplary embodiment of theswirler510 shown therein, eachvane508 has aroot portion520 located radially near thesplitter530 and atip portion521 that is located radially near theventuri wall502. Eachvane508 has aleading edge512 and a trailingedge514 that extend between theroot portion520 and thetip portion521. Thevanes508 have a suitable shape, such as, for example, an airfoil shape, between theleading edge512 and the trailingedge514. Circumferentiallyadjacent vanes508 form a flow passage for passing air, such as the CDP air shown asitem190 inFIG. 2, that enters theswirler510. Thevanes208 can be inclined both radially and axially relative to theswirler axis11 to impart a rotational component of motion to theincoming air190 that enters theswirler510. Theseinclined vanes508 cause theair190 to swirl in a generally helical manner withinventuri500. In one aspect of the present invention, thevane508 has afillet526 that extends between theroot portion520 of thevane508 and thesplitter wall532. In addition to facilitating reduction of stress concentrations in theroot portion510, thefillet526 also facilitates a smooth flow of air within the swirler and in the swirledair passage534. Thefillet526 has asmooth contour shape527 that is designed to promote the smooth flow of air in the swirler. The contour shapes and orientations for aparticular vane508 are designed using known methods of fluid flow analysis. Fillets similar tofillets526 having suitable fillet contours may also be used between thetip portion521 of thevane508 and theventuri wall502. In the exemplary embodiment of theventuri500 shown inFIGS. 3-7 herein, thevanes508 are supported near both theroot portion520 and thetip portion521. It is also possible, in some alternative venturi designs, to have a swirler comprising vanes having a cantilever-type of support, wherein a vane is structurally supported at only one end, with the other end essentially free. Theventuri500 may be manufactured from known materials that can operate in high temperature environments, such as, for example, nickel or cobalt based super alloys, such as CoCr, HS188, N2 and N5.
• Theventuri500 comprises aheat shield540 for protecting venturi and other components in the fuel nozzle tip assembly68 (seeFIG. 3) from the flames and heat from ignition of the fuel/air mixture in afuel nozzle100. Theexemplary heat shield540 shown inFIGS. 5-7 has an annular shape around theswirler axis11 and is located axially aft from theswirler510, near the axiallyaft end519 of theventuri500. Theheat shield540 has anannular wall542 that extends in a radially outward direction from theswirler axis11. Theannular wall542 protectsventuri500 and other components in the fuelnozzle tip assembly68 from the flames and heat from ignition of the fuel/air mixture, having temperatures in the range of 2500 Deg. F to 4000 Deg. F. Theheat shield540 is made from a suitable material that can withstand high temperatures. Materials such as, for example, CoCr, HS188, N2 and N5 may be used. In the exemplary embodiments shown herein, theheat shield540 is made from CoCr material, and has a thickness between 0.030 inches and 0.060 inches. It is possible, in other embodiments of the present invention, that theheat shield540 may be manufactured from a material that is different from the other portions the venturi, such as theventuri wall502 or theswirler510.
• Theexemplary venturi500 shown inFIGS. 5-7 has certain design features that enhance the cooling of theheat shield540 to reduce its operating temperatures. Theexemplary venturi500 comprises at least oneslot544 extending between theventuri wall502 and theheat shield540. The preferred exemplary embodiment of theventuri500, shown inFIG. 6, comprises a plurality ofslots544 extending between theventuri wall502 and theheat shield540 wherein theslots544 are arranged circumferentially around theswirler axis11. Theslots544 provide an exit passage for cooling air that flows through the cavity between the fuel conduit and the venturi wall502 (SeeFIG. 3). The cooling air entering the axially oriented portion of each slot544 (seeFIG. 3,5) is redirected in the radially oriented portion of the slot544 (seeFIG. 3,5) to exit from theslots544 in a generally radial direction onto the side of theannular wall542 of the heat shield. In another aspect of the present invention, theexemplary venturi500 comprises a plurality ofbumps546 located on theheat shield540 and arranged circumferentially on the axially forward side of theheat shield wall542 around theswirler axis11. Thesebumps546 provide additional heat transfer area and increase the heat transfer from theheat shield540 to the cooling air directed towards, thereby reducing the operating temperatures of theheat shield540. In the exemplary embodiment shown inFIG. 6, thebumps546 are arranged in four circumferential rows, with each row having between 100 and 120 bumps.
• An alternative exemplary embodiment of the present invention of a venturi is shown inFIG. 8.FIG. 8 is an isometric view of the alternativeexemplary venturi600 with a portion sectioned away. Referring toFIGS. 3 and 6, it is apparent to those skilled in the art that the airflow entering theswirler510 of theventuri500, in some cases, may not be uniform in the circumferential direction when it enters passages between thevanes508. This non-uniformity is further enhanced by the presence of other features, such as, for example, the wall260 (seeFIG. 3). In conventional venturis, such non-uniformity of the flow may cause non-uniformities in the mixing of fuel and air in the venturi and lead to non-uniform combustion temperatures. In one aspect of the present invention of a venturi600 (seeFIG. 8), the adverse effects of circumferentially non-uniform flow entry can be minimized by having aswirler610 comprisingswirler vanes609 with geometries that are different from those of circumferentiallyadjacent vanes608. Customizedswirler vane608,609 geometries can be selected for each circumferential location based on known fluid flow analytical techniques. In the alternative exemplary embodiment of the present invention shown inFIG. 8, thevane609 has an axial recess635 for suitably receiving an air flow that has been altered locally, such as, for example, due to the presence of awall260 in an adjacent component in a fuel nozzle assembly tip68 (seeFIG. 3). The alternative embodiment of theventuri600 further comprises aheat shield640,splitter630,venturi wall602, and other features as described previously herein for theexemplary venturi500. Aventuri600 having swirlers with different geometries for thevanes608,609 located at different circumferential locations can have a unitary construction and made using the methods of manufacture described herein.
• The exemplary embodiments of theunitary venturi500 shown inFIGS. 5-7, and the alternative embodiments of theunitary venturi600 shown inFIG. 8, can be made using rapid manufacturing processes such as Direct Metal Laser Sintering (DMLS), Laser Net Shape Manufacturing (LNSM), electron beam sintering and other known processes in the manufacturing. DMLS is a preferred method of manufacturingunitary venturis500,600 described herein.
• FIG. 9 is a flow chart illustrating an exemplary embodiment of amethod700 for fabricating unitary venturis, such asitems500 and600 described herein, and shown inFIGS. 3-8. Although the method offabrication700 is described below usingunitary venturi500 as an example, the same methods, steps, procedures, etc. apply for the alternative exemplary embodiment of theventuri600 shown inFIG. 8.Method700 includes fabricating unitary venturi500 (shown inFIGS. 3-7) using Direct Metal Laser Sintering (DMLS). DMLS is a known manufacturing process that fabricates metal components using three-dimensional information, for example a three-dimensional computer model, of the component. The three-dimensional information is converted into a plurality of slices, each slice defining a cross section of the component for a predetermined height of the slice. The component is then “built-up” slice by slice, or layer by layer, until finished. Each layer of the component is formed by fusing a metallic powder using a laser.
• Accordingly,method700 includes thestep705 of determining three-dimensional information of aunitary venturi500 and thestep710 of converting the three-dimensional information into a plurality of slices that each define a cross-sectional layer of theunitary venturi500. Theunitary venturi500 is then fabricated using DMLS, or more specifically each layer is successively formed instep715 by fusing a metallic powder using laser energy. Each layer has a size between about 0.0005 inches and about 0.001 inches.Unitary venturi500 may be fabricated using any suitable laser sintering machine. Examples of suitable laser sintering machines include, but are not limited to, an EOSINT.®. M 270 DMLS machine, a PHENIX PM250 machine, and/or an EOSINT.®.M 250 Xtended DMLS machine, available from EOS of North America, Inc. of Novi, Mich. The metallic powder used to fabricateunitary venturi500 is preferably a powder including cobalt chromium, but may be any other suitable metallic powder, such as, but not limited to, HS188 and INCO625. The metallic powder can have a particle size of between about 10 microns and 74 microns, preferably between about 15 microns and about 30 microns.
• Although the methods of manufacturingunitary venturi500 have been described herein using DMLS as the preferred method, those skilled in the art of manufacturing will recognize that any other suitable rapid manufacturing methods using layer-by-layer construction or additive fabrication can also be used. These alternative rapid manufacturing methods include, but not limited to, Selective Laser Sintering (SLS), 3D printing, such as by inkjets and laserjets, Sterolithography (SLS), Direct Selective Laser Sintering (DSLS), Electron Beam Sintering (EBS), Electron Beam Melting (EBM), Laser Engineered Net Shaping (LENS), Laser Net Shape Manufacturing (LNSM) and Direct Metal Deposition (DMD).
• Theunitary venturi500 for afuel nozzle100 in a turbine engine (seeFIGS. 1-3) comprises fewer components and joints than known venturis, swirlers and fuel nozzles. Specifically, the above describedunitary venturi500 requires fewer components because of the use of a one-pieceunitary venturi500 comprising aswirler510 having a plurality ofvanes508, aventuri wall502 and aheat shield540. As a result, the describedunitary venturi500 provides a lighter, less costly alternative to known venturis. Moreover, the described unitary construction for theunitary venturi500 provides fewer opportunities for leakage or failure and is more easily repairable compared to known venturis.
• As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. When introducing elements/components/steps etc. ofunitary venturi500,600 described and/or illustrated herein, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the element(s)/component(s)/etc. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional element(s)/component(s)/etc. other than the listed element(s)/component(s)/etc. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
• Although the methods and articles such asunitary venturi500,600 described herein are described in the context of swirling of air for mixing liquid fuel with air in fuel nozzles in a turbine engine, it is understood that theunitary venturi500,600 and methods of their manufacture described herein are not limited to fuel nozzles or turbine engines. Theunitary venturi500,600 illustrated in the figures included herein are not limited to the specific embodiments described herein, but rather, these can be utilized independently and separately from other components described herein.
• This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims (21)

1. A venturi comprising:

an annular venturi wall;

a mixing cavity surrounded circumferentially by the annular wall; and

a swirler having a plurality of vanes arranged circumferentially around a swirler axis, wherein the swirler and the annular venturi wall have a unitary construction.

2. A venturi according toclaim 1 wherein the swirler is located at an axially forward end of the venturi.

3. A venturi according toclaim 1 further comprising an annular splitter located radially inward from the annular venturi wall.

4. A venturi according toclaim 3 wherein the plurality of vanes extend between the venturi wall and the annular splitter.

5. A venturi according toclaim 3 wherein the splitter comprises an annular splitter wall coaxially located around the swirler axis.

6. A venturi according toclaim 3 further comprising an annular swirled-air passage between an outer surface of the splitter and an inner surface of the venturi.

7. A venturi according toclaim 1 wherein each vane has a leading edge and a trailing edge located axially forward from the leading edge, and has an orientation that facilitates producing a swirling motion to an airflow flowing through the swirler.

8. A venturi according toclaim 1 wherein each vane has substantially the same geometry.

9. A venturi according toclaim 1 wherein at least one vane has a geometry that is different from another vane.

10. A venturi according toclaim 1 further comprising a fillet between a root portion of a vane and the splitter.

11. A venturi according toclaim 10 wherein the fillet has a contour that facilitates a smooth flow of air in the swirler.

12. A venturi according toclaim 5 wherein the splitter wall has a recess that facilitates interfacing the venturi with an adjacent component during assembly.

13. A venturi according toclaim 1 further comprising at least one groove located on the venturi wall capable of receiving a brazing material.

14. A venturi according toclaim 1 further comprising a lip located at an axially aft end of the venturi.

15. A venturi comprising:

an annular venturi wall;

a swirler located at an axially forward portion of the venturi, the swirler having a plurality of vanes arranged circumferentially around a swirler axis; and

a heat shield located axially aft from the swirler, wherein the annular venturi wall, the swirler and the heat shield have a unitary construction.

16. A venturi according toclaim 15 wherein the heat shield is annular.

17. A venturi according toclaim 15 wherein the heat shield is located at an axially aft end of the venturi.

18. A venturi according toclaim 16 further comprising at least one slot extending between the venturi wall and the heat shield.

19. A venturi according toclaim 16, further comprising a plurality of slots extending between the venturi wall and the heat shield, the slots being arranged circumferentially around the swirler axis.

20. A venturi according toclaim 16, further comprising a plurality of bumps located on the heat shield and arranged circumferentially around the swirler axis.

21. A venturi according toclaim 16, further comprising a lip located at the axially aft end of the venturi wall.

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