Mixer Assembly for a Gas Turbine Engine

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(12) United States Patent (io) Patent No.:

US 9,920,932 B2

Dai et al. (45) Date of Patent: Mar.

20,2018

(54) MIXER ASSEMBLY FOR A GAS TURBINE (58) Field of Classification Search ENGINE CPC .. F23R 3/14; F23R 3/286; F23R 2900/03343; F23C 7/004 (71) Applicant: UNITED TECHNOLOGIES See application file for complete search history.

CORPORATION, Farmington, CT (US) (56) References Cited (72) Inventors: Zhongtao Dai, Manchester, CT (US); U.S. PATENT DOCUMENTS Jeffrey M. Cohen, Hebron, CT (US); Catalin G. Fotache, West Hartford, CT 3,703,259 A 11/1972 Sturgess et al.

3,946,552 A 3/1976 Weinstein et al.

(US); Lance L. Smith, West Hartford, 5,165,241 A 11/1992 Joshi et al.

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(73) Assignee: UNITED TECHNOLOGIES 5,623,827 A 4/1997 Monty CORPORATION, Farmington, CT (Continued) (US) FOREIGN PATENT DOCUMENTS (*) Notice: Subject to any disclaimer, the term ofthis DE 102007043383 Al 3/2008 patent is extended or adjusted under 35 EP 0041878 A2 12/1981 U.S.C. 154(b) by 80 days.

(Continued) (21) Appl. No.: 14/593,877 OTHER PUBLICATIONS (22) Filed: Jan. 9, 2015 English Abstract for EP0041878A2 Dec. 16, 1981; 2 pgs.

(65) Prior Publication Data (Continued) US 2015/0121882 Al May 7, 2015 Primary Examiner Steven Sutherland Related U.S. Application Data (74) Attorney, Agent, or Firm Cantor Colburn LLP (63) Continuation of application No. 13/014,388, filed on Jan. 26, 2011, now Pat. No. 8,973,368. (57) ABSTRACT A mixer assembly for a gas turbine engine is provided, (51) Int. Cl.

including a main mixer with fuel injection holes located F23R 3/14 (2006.01) between at least one radial swirler and at least one axial F23R 3/28 (2006.01) swirler, wherein the fuel injected into the main mixer is F23C 7/00 (2006.01) atomized and dispersed by the air flowing through the radial (52) U.S. Cl.

swirler and the axial swirler.

CPC .............. F23R 3/286 (2013.01); F23C 7/004 (2013.01); F23R 3/14 (2013.01); F23R 2900103343 (2013.01) 16 Claims, 4 Drawing Sheets / J 200

US 9,920,932 B2

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Mar. Sheet 1 of 4

U.S. Patent 20,2018 US 9,920,932 B2

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FIG. 1

Mar. Sheet 2 of 4

U.S. Patent 20,2018 US 9,920,932 B2

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Mar. Sheet 3 of 4

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~-200 X240 242 d 23C we r— 218

FIG. 3

Patent Mar. 2018 Sheet 4 of 4 9,920,932 B2

U.S. 20, US

2E FIG.

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MIXER ASSEMBLY FOR A GAS TURBINE Combustion of the hydrocarbon fuel in air in gas turbine ENGINE engines inevitably produces emissions, such as oxides of nitrogen (NOx), carbon dioxide (CO2 ), carbon monoxide CROSS-REFERENCE TO RELATED (CO),unburned hydrocarbons(UHC),and smoke, which are APPLICATIONS 5 delivered into the atmosphere in the exhaust gases from the gas turbine engine. Regulations limiting these emissions have become more stringent. At the same time, the engine This application is a continuation patent application under pressure ratio is getting higher and higher for increasing 35 USC § 120 claiming priority to U.S. non-provisional engine efficiency, lowering specific fuel consumption, and patent application Ser. No. 13/014,388 filed on Jan. 26, lowering carbon dioxide(CO2 )emissions, resulting in sig- 2011. This application is related to co-pending, commonly- nificant challenges to designing combustors that still pro- assigned U.S. patent application (application Ser. No.

duce low emissions despite increased combustor inlet pres- 13/014,434, now U.S. Pat. No. 8,312,724), entitled "MIXER sure, temperature, and fuel/air ratio. Due to the limitation of ASSEMBLY FOR A GAS TURBINE ENGINE," filed on emission reduction potential for the rich burn-quick quench- Jan. 26, 2011, and is incorporated herein by reference in its lean burn (RQL) combustor, lean burn combustors, and in entirety.

particular the piloted lean premixed/partially premixed pre- vaporized combustor (PLPP), have become used more fre- STATEMENT OF FEDERALLY SPONSORED quently for further reduction of emissions. However, one of RESEARCH OR DEVELOPMENT the major challenges for the development of PLPP is the requirement to sufficiently premix the injected fuel and This invention was made with Government support under combustion air in the main mixer ofa mixer assembly within Contract No. NNC08CA92C awarded by the National Aero- a given mixing time, which is required to be significantly nautics and Space Administration (NASA). The U.S. Gov- shorter than the auto-ignition delay time.

ernment has certain rights in the invention.

Mixer assemblies for existing PLPP combustors typically include a pilot mixer surrounded by a main mixer with a fuel FIELD OF THE DISCLOSURE manifold provided between the two mixers to inject fuel radially into the cavity of the main mixer through fuel The subject matter disclosed herein relates generally to injection holes. The main mixer typically employs air swirl- combustors for gas turbine engines and more particularly to ers proximate and upstream of the fuel injection holes to mixer assemblies for gas turbine engines. 30 impart a swirl to the air entering the main mixer and to provide rapid mixing ofthe air and the fuel, which is injected BACKGROUND OF THE DISCLOSURE perpendicularly into the cross flow of the air atomizing the fuel for mixing with the air. The level of atomization and Gas turbine engines, such as those used to power modern mixing in this main mixer configuration is largely dependent aircraft, to power sea vessels, to generate electrical power, 35 upon the penetration of the fuel into the air, which in turn is and in industrial applications, include a compressor for dependent upon the ratio of the momentum of the fuel to the pressurizing a supply of air, a combustor for burning a momentum of the air. As a result, the degree of atomization hydrocarbon fuel in the presence of the pressurized air, and and mixing may vary greatly for different gas turbine engine a turbine for extracting energy from the resultant combus- operating conditions (e.g.,low power conditions where there tion gases. Generally, the compressor, combustor, and tur- 40 is poor atomization and mixing may result in higher emis- bine are disposed about a central engine axis with the sions than high power conditions where there is better compressor disposed axially upstream or forward of the atomization and mixing). In addition, since the fuel injection combustor and the turbine disposed axially downstream of holes are typically located downstream of the point where the combustor. In operation of a gas turbine engine, fuel is the air swirlers produce the maximum turbulence, the degree injected into and combusted in the combustor with com- 45 of atomization and mixing is not maximized, increasing the pressed air from the compressor thereby generating high- amount of emissions. Furthermore, since the fuel injection temperature combustion exhaust gases, which pass through holes are typically located downstream of the air swirlers, the turbine and produce rotational shaft power. The shaft the risk offlashback, flame holding and autoignition greatly power is used to drive a compressor to provide air to the increases due to the low velocity regions associated with combustion process to generate the high energy gases. 50 fuel jets and walls. A highly possible source for flashback, Additionally, the shaft power is used to, for example, drive flame holding and autoignition in the typical main mixer is a generator for producing electricity, or drive a fan to caused by a wake region that can form downstream of the produce high momentum gases for producing thrust.

fuel injection holes where injected fuel that has not suffi- An exemplary combustor features an annular combustion ciently penetrated into the cross flow of the air (e.g., when chamber defined between a radially inboard liner and a 55 air is flowing at low velocity) will gather and potentially radially outboard liner extending aft from a forward bulk- ignite. Another possible source is related to boundary layers head wall. The radially outboard liner extends circumferen- along the wall, which is thickened by fuel jets due to reduced tially about and is radially spaced from the inboard liner, velocity.

with the combustion chamber extending fore to aft between the liners. A plurality of circumferentially distributed fuel 60 SUMMARY OF THE DISCLOSURE injectors are mounted in the forward bulkhead wall and project into the forward end of the annular combustion A mixer assembly for a gas turbine engine is provided, chamber to supply the fuel to be combusted. Air swirlers including a main mixer with fuel injection holes located proximate to the fuel injectors impart a swirl to inlet air between at least one radial swirler and at least one axial entering the forward end of the combustion chamber at the 65 swirler, wherein the fuel injected into the main mixer is bulkhead wall to provide rapid mixing of the fuel and inlet atomized and dispersed by the air flowing through the radial air. swirler and the axial swirler. This configuration reduces the

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_►, dependence upon the ratio of the momentum of the fuel to is depicted as a turbofan that incorporates a fan section 20, the momentum ofthe air, increases the degree ofatomization a compressor section 30, a combustion section 40, and a turbine section 50. The combustion section 40 incorporates and mixing by injecting the fuel at a point of high turbu- a combustor 100 that includes a plurality of fuel injectors lence, and reduces the potential for flame holding by reduc- 5 150 that are positioned annularly about a centerline 2 of the ing the potential for forming a wake region and lengthening engine 10 upstream of the turbines 52, 54. Throughout the the potential mixing distance.

application, the terms "forward" or "upstream" are used to According to one embodiment, a mixer assembly for a gas refer to directions and positions located axially closer turbine engine is provided. The mixer assembly includes a toward a fuel/air intake side of a combustion system than main mixer comprising an annular inner radial wall, an io directions and positions referenced as "aft" or "down- annular outer radial wall surrounding at least a portion ofthe stream." The fuel injectors 150 are inserted into and provide annular inner radial wall, wherein the annular outer radial fuel to one or more combustion chambers for mixing and/or wall incorporates a first outer radial wall swirler with a first ignition. It is to be understood that the combustor 100 and axis oriented substantially radially to a centerline axis of the fuel injector 150 as disclosed herein are not limited in mixer assembly, a forward wall substantially perpendicular 15 application to the depicted embodiment of a gas turbine to and connecting the annular inner radial wall and the engine 10, but are applicable to other types of gas turbine annular outer radial wall forming an annular cavity, wherein engines, such as those used to power modern aircraft, to the forward wall incorporates a first forward wall swirler power sea vessels, to generate electrical power, and in with a second axis oriented substantially axially to the industrial applications.

centerline axis of the mixer assembly, and a plurality offuel 20 FIG. 2 is a partial perspective view of an exemplary injection holes in the forward wall between the first outer embodiment of a combustor 100 of a gas turbine engine 10.

radial wall swirler and the first forward wall swirler, wherein The combustor 100 is positioned between the compressor the first outer radial wall swirler is on a first side of the section 30 and the turbine section 50 of a gas turbine engine plurality of fuel injection holes and the first forward wall 10. The exemplary combustor 100 includes an annular swirler is on a second side of the plurality of fuel injection 25 combustion chamber 130 bounded by an inner (inboard) holes.

wall 132 and an outer (outboard) wall 134 and a forward In another embodiment, a mixer assembly for a gas bulkhead wall 136 spanning between the walls 132, 134 at turbine engine is provided. The mixer assembly includes a the forward end of the combustor 100. The bulkhead wall main mixer comprising an annular inner radial wall, an 136 of the combustor 100 carries a plurality of mixer annular outer radial wall surrounding at least a portion ofthe so assemblies 200, including the fuel nozzle 152 of a fuel annular inner radial wall, wherein the annular outer radial injector 150, a main mixer 220, and a pilot mixer 210. It will wall incorporates a plurality of outer radial wall swirlers be understood that, although only a single mixer assembly with a first axis oriented substantially radially to a centerline 200 is shown in FIG. 2 for illustrative purposes, the com- axis of the mixer assembly, a forward wall substantially bustor 100 may include a plurality of mixer assemblies 200 perpendicular to and connecting the annular inner radial wall 35 circumferentially distributed and mounted at the forward and the annular outer radial wall forming an annular cavity, end of the combustor 100. A number of sparkplugs (not wherein the forward wall incorporates a first forward wall shown) are positioned with their working ends along a swirler with a second axis oriented substantially axially to forward portion of the combustion chamber 130 to initiate the centerline axis of the mixer assembly, and a plurality of combustion of the fuel and air mixture. The combusting fuel injection holes in the forward wall between the plurality 40 mixture is driven downstream within the combustor 100 of outer radial wall swirlers and the first forward wall along a principal flowpath 170 toward the turbine section 50 swirler, wherein the plurality of outer radial wall swirlers is ofthe engine 10. The fuel and air provided to the pilot mixer on a first side of the plurality offuel injection holes and the 210 produce a primary combustion zone 110 within a central first forward wall swirler is on a second side of the plurality portion of the combustion chamber 130. The fuel and air of fuel injection holes.

45 provided to the main mixer 220 produce a secondary com- bustion zone 120 in the combustion chamber 130 that is BRIEF DESCRIPTION OF THE DRAWINGS radially outwardly spaced from and concentrically sur- rounds the primary combustion zone 110.

For a further understanding of the disclosure, reference FIG. 3 is an enlarged partial perspective view of an will be made to the following detailed description which is 50 exemplary embodiment of the mixer assembly 200 for the to be read in connection with the accompanying drawing, exemplary combustor 100 of FIG. 2. The exemplary mixer wherein: FIG. 1 is a schematic diagram of an exemplary embodi- assembly 200 includes a main mixer 220 and a pilot mixer 210. The pilot mixer 210 and the main mixer 220 are ment of a gas turbine engine.

concentrically arranged with the pilot mixer 210 located in FIG. 2 is a partial perspective view of an exemplary embodiment of a combustor of a gas turbine engine. 55 the center of the main mixer 220, which surrounds a portion of the pilot mixer 210. The mixer assembly 200 has a FIG. 3 is an enlarged partial perspective view of an centerline axis 218. The pilot mixer 210 includes an annular exemplary embodiment of a mixer assembly for the exem- plary combustor of FIG. 2. pilot mixer housing 212 separating and sheltering the pilot mixer 210 from the main mixer 220. The main mixer 220 FIG. 4 is an enlarged partial perspective view of another 60 further includes an annular main mixer outer radial wall 222 exemplary embodiment of a mixer assembly for the exem- radially surrounding a portion of the annular pilot mixer plary combustor of FIG. 2.

housing 212, the outer surface of which forms an annular DETAILED DESCRIPTION OF THE main mixer inner radial wall 219, and a main mixer forward DISCLOSURE wall 224 substantially perpendicular to and connecting the 65 annular main mixer outer radial wall 222 and the annular FIG. 1 is a schematic diagram of an exemplary embodi- main mixer inner radial wall 219, forming a main mixer ment of a gas turbine engine 10. The gas turbine engine 10 annular cavity 228. The annular main mixer outer radial wall

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222 further incorporates a first outer radial wall swirler 240, main mixer forward wall 224 and be oriented substantially while the main mixer forward wall 224 further incorporates perpendicularly to the axis of the first forward wall swirler a first forward wall swirler 230 and a plurality of fuel 230 and the flow of air from the radial first forward wall injection holes 226 circumferentially distributed between swirler 230, which atomizes and disperses the fuel. The fuel the first outer radial wall swirler 240 and the first forward 5 then is atomized and dispersed again by the flow of air from wall swirler 230 around the main mixer forward wall 224.

the axial first outer radial wall swirler 240, thus atomizing Although shown proximate to the first outer radial wall the fuel by airflow from two sides. In either configuration, an swirler 240 in the main mixer forward wall 224, the fuel intense mixing region 229 of fuel and air is created within injection holes 226 can be located proximate the first for- annular main mixer cavity 228 axially adjacent to the fuel ward wall swirler 230 in the main mixer forward wall 224 io injection holes 226, allowing the majority of fuel and air to as well. The fuel injection holes 226 are in flow communi- be mixed before entering the downstream end ofthe annular cation with a fuel manifold (not shown), which in turn is in main mixer cavity 228. This configuration reduces the flow communication with a fuel supply. Although described dependence upon the ratio of the momentum of the fuel to with respect to liquid fuel, the exemplary embodiments of the momentum ofthe air, increases the degree ofatomization mixer assemblies 200 can also be used with gaseous fuel or 15 and mixing by injecting the fuel at a point of high turbu- partially vaporized fuel. As can be seen in FIG. 3, the first lence, and reduces the potential for flame holding by reduc- outer radial wall swirler 240 is positioned on a first side of ing the potential for forming a wake region and lengthening the fuel injection holes 226, while the first forward wall the potential mixing distance. The configuration ofthe vanes swirler 230 is positioned on a second side of the fuel in the swirlers may be altered to vary the swirl direction of injection holes 226. In one embodiment, the first side is 20 substantially opposite of the second side. air flowing and are not limited to the exemplary swirl The first outer radial wall swirler 240 is incorporated into directions indicated. Furthermore, the number of radial and the annular main mixer outer radial wall 222 and has an axis axial swirlers can be modified (e.g., the first outer radial wall 248 oriented substantially radially to the centerline axis 218 swirler 240 can be replaced by a plurality of radial swirlers of the mixer assembly 200. The first forward wall swirler 25 and the first forward wall swirler 230 can be replaced by a 230 is incorporated into the main mixer forward wall 224 plurality of axial swirlers).

and is oriented substantially parallel or axially to the cen- FIG. 4 is an enlarged partial perspective view of another terline axis 218 ofthe mixer assembly 200. The swirlers 230, exemplary embodiment of the mixer assembly 200 for the 240 each have a plurality of vanes for swirling air traveling exemplary combustor 100 of FIG. 2. As in FIG. 3, the through the swirlers to mix the air and the fuel dispensed by 30 exemplary mixer assembly 200 includes a main mixer 220 the fuel injection holes 226. The first outer radial wall and a pilot mixer 210. The pilot mixer 210 includes an swirler 240 includes a first plurality of vanes 242 forming a annular pilot mixer housing 212 separating and sheltering first plurality of air passages 244 between the vanes 242. The the pilot mixer 210 from the main mixer 220. The main vanes 242 are oriented at an angle with respect to axis 248 mixer 220 further includes an annular main mixer outer to cause the air to rotate in the main mixer annular cavity 228 35 radial wall 222 radially surrounding a portion of the annular in a first direction (e.g., clockwise). The first forward wall pilot mixer housing 212, the outer surface of which forms an swirler 230 includes a second plurality ofvanes 232 forming annular main mixer inner radial wall 219, and a main mixer a second plurality of air passages 234 between the vanes forward wall 224 substantially perpendicular to and con- 232. The vanes 232 are oriented at an angle with respect to necting the annular main mixer outer radial wall 222 and the the centerline axis 218 to cause the air to rotate in the main 40 annular main mixer inner radial wall 219, forming a main mixer annular cavity 228 in a second direction (e.g., coun- mixer annular cavity 228. The annular main mixer outer terclockwise). radial wall 222 further incorporates a plurality ofouter radial In the exemplary embodiment of the main mixer 220 wall swirlers, including a first outer radial wall swirler 270, shown in FIG. 3, the air flowing through the first outer radial a second outer radial wall swirler 280, and a third outer wall swirler 240 will be swirled in a first direction and the 45 radial wall swirler 290, while the main mixer forward wall air flowing through the first forward wall swirler 230 will be 224 further incorporates a plurality offorward wall swirlers, swirled in a direction substantially opposite of the first including a first forward wall swirler 250, a second forward direction. Also, in the exemplary embodiment of the main wall swirler 260, and a plurality of fuel injection holes 226 mixer 220 shown in FIG. 3, the air flowing through the first circumferentially distributed between the second forward outer radial wall swirler 240 has an axis 248 oriented 50 wall swirler 260 and the first outer radial wall swirler 270 substantially radially to the centerline axis 218 of the mixer around the main mixer forward wall 224. Although shown assembly 200, while the air flowing through the first forward proximate to the first outer radial wall swirler 270 in the wall swirler 230 has an axis oriented substantially axially to main mixer forward wall 224, the fuel injection holes 226 the centerline axis 218 of the mixer assembly 200. In this can be located proximate the second forward wall swirler configuration, the fuel is injected through the fuel injection 55 260 in the main mixer forward wall 224 as well. The fuel holes 226 between the radial first outer radial wall swirler injection holes 226 are in flow communication with a fuel 240 and the axial first forward wall swirler 230. In one manifold (not shown), which in turn is in flow communi- embodiment, the fuel is injected through the fuel injection cation with a fuel supply. Although described with respect to holes 226 that are oriented substantially perpendicularly to liquid fuel, the exemplary embodiments of mixer assemblies axis 248 and the flow of air from the radial first outer radial 60 200 can also be used with gaseous fuel or partially vaporized wall swirler 240, which atomizes and disperses the fuel. The fuel. As can be seen in FIG. 4, the first, second, and third fuel then is atomized and dispersed again by the flow of air outer radial wall swirlers 270, 280, 290 are positioned on a from the axial first forward wall swirler 230, thus atomizing first side of the fuel injection holes 226, while the first and the fuel by airflow from two sides. Although shown proxi- second forward wall swirlers 250, 260 are positioned on the mate to the first outer radial wall swirler 240 in the main 65 second side of the fuel injection holes 226. In one embodi- mixer forward wall 224, the fuel injection holes 226 can be ment, the first side is substantially opposite of the second located proximate the first forward wall swirler 230 in the side.

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The first, second, and third outer radial wall swirlers 270, wall swirlers 270, 280, 290), which atomizes and disperses 280, 290 are incorporated into the annular main mixer outer the fuel. The fuel then is atomized and dispersed again by the radial wall 222 and each have an axis 248 oriented substan- flow of air from the plurality of forward wall swirlers (first tially radially to the centerline axis 218 of the mixer assem- and second forward wall swirlers 240, 250), thus atomizing bly 200. The first and second forward wall swirlers 250,260 5 the fuel by airflow from two sides. Although shown proxi- are incorporated into the main mixer forward wall 224 and mate to the plurality of outer radial wall swirlers 270, 280, are oriented substantially parallel or axially to the centerline 290 in the main mixer forward wall 224, the fuel injection axis 218 ofthe mixer assembly 200. Swirlers 250,260, 270, holes 226 can be located proximate the plurality offorward 280, 290 each have a plurality of vanes for swirling air wall swirlers 250, 260 in the main mixer forward wall 224 traveling through the swirlers to mix the air and the fuel io and be oriented substantially perpendicularly to the axis and dispensed by the fuel injection holes 226. the flow of air from the plurality of forward wall swirlers The first outer radial wall swirler 270 includes a first 250, 260, which atomizes and disperses the fuel. The fuel plurality ofvanes 272 forming a first plurality of air passages then is atomized and dispersed again by the flow of air from 274 between the vanes 272. The vanes 272 are oriented at an the plurality of outer radial wall swirlers 270, 280,290, thus angle with respect to axis 248 to cause the air to rotate in the 15 atomizing the fuel by airflow from two sides. In either main mixer annular cavity 228 in a first direction (e.g., configuration, an intense mixing region 229 of fuel and air clockwise). The second outer radial wall swirler 280 is created within annular main mixer cavity 228 axially includes a second plurality of vanes 282 forming a second adjacent to the fuel injection holes 226, allowing the major- plurality of air passages 284 between the vanes 282. The ity of fuel and air to be mixed before entering the down- vanes 282 are oriented at an angle with respect to axis 248 20 stream end of the annular main mixer cavity 228. The to cause the air to rotate in the main mixer annular cavity 228 number of axial swirlers, the number of radial swirlers, and in a second direction (e.g., counterclockwise). The third the configuration of the vanes in the swirlers may be altered outer radial wall swirler 290 includes a third plurality of to vary the swirl direction of air flowing and are not limited vanes 292 forming a third plurality of air passages 294 to the exemplary swirl directions indicated.

between the vanes 292. The vanes 292 are oriented at an 25 The terminology used herein is for the purpose of descrip- angle with respect to axis 248 to cause the air to rotate in the tion, not limitation. Specific structural and functional details main mixer annular cavity 228 in a third direction. In one disclosed herein are not to be interpreted as limiting, but embodiment, the third direction can be substantially the merely as basis for teaching one skilled in the art to employ same as the first direction which are substantially opposite of the present invention. While the present invention has been the second direction. 30 particularly shown and described with reference to the The first forward wall swirler 250 includes a fourth exemplary embodiments as illustrated in the drawing, it will plurality of vanes 252 forming a fourth plurality of air be recognized by those skilled in the art that various modi- passages 254 between the vanes 252. The vanes 252 are fications may be made without departing from the spirit and oriented at an angle with respect to the centerline axis 218 scope of the invention. Those skilled in the art will also to cause the air to rotate in the main mixer annular cavity 228 35 recognize the equivalents that may be substituted for ele- in a fourth direction (e.g., counterclockwise). The second ments described with reference to the exemplary embodi- forward wall swirler 260 includes a fifth plurality of vanes ments disclosed herein without departing from the scope of 262 forming a fifth plurality of air passages 264 between the the present invention. Therefore, it is intended that the vanes 262. The vanes 262 are oriented at an angle with present disclosure not be limited to the particular embodi- respect to the centerline axis 218 to cause the air to rotate in 40 ment(s) disclosed as, but that the disclosure will include all the main mixer annular cavity 228 in a fifth direction (e.g., embodiments falling within the scope of the appended clockwise). In one embodiment, the fourth direction is claims.

substantially opposite of the fifth direction. We claim: In the exemplary embodiment of the main mixer 220 1. A mixer assembly for a gas turbine engine comprising: shown in FIG. 4, the clockwise air passing through the first 45 a main mixer comprising: outer radial wall swirler 270 and the third outer radial wall an annular inner radial wall; swirler 290 counter-rates against the counterclockwise air an annular outer radial wall surrounding at least a portion passing through the second outer radial wall swirler 280, of the annular inner radial wall, wherein the annular increasing the turbulence, which improves mixing. Also, the outer radial wall incorporates a first outer radial wall counterclockwise air passing through the first forward wall 50 swirler with a first axis oriented radially to a centerline swirler 250 counter-rates against the clockwise air passing axis of the mixer assembly; through the second forward wall swirler 260, increasing the a forward wall extending radially outward with respect to turbulence, which improves mixing. In addition, the air the first axis and connecting the annular inner radial flowing through the first, second, and third outer radial wall wall and the annular outer radial wall, the inner radial swirlers 270, 280,290 has an axis 248 oriented substantially 55 wall, forward wall, and outer radial wall forming a radially to the centerline axis 218 ofthe mixer assembly 200, single annular cavity therebetween, wherein the for- while the air flowing through the first and second forward ward wall incorporates a first forward wall swirler with wall swirlers 250, 260 has an axis oriented substantially a second axis oriented axially to the centerline axis of axially to the centerline axis 218 ofthe mixer assembly 200. the mixer assembly; and In this configuration, the fuel is injected through the fuel 60 a plurality of fuel injection holes in the forward wall injection holes 226 between the radial first, second, and third between the first outer radial wall swirler and the first outer radial wall swirlers 270, 280, 290 and the axial first forward wall swirler, the plurality of fuel injection and second forward wall swirlers 250, 260. holes oriented to inject a fuel into the main mixer, In one embodiment, the fuel is injected through the fuel wherein the fuel is atomized and dispersed by airflow injection holes 226 that are oriented substantially perpen- 65 from the first outer radial wall swirler and is subse- dicularly to axis 248 and the flow of air from the plurality of quently atomized and dispersed by airflow from the outer radial wall swirlers (first, second, and third outer radial first forward wall swirler, wherein the first outer radial

US 9,920,932 B2

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wall swirler is on a first side of the plurality of fuel the first forward wall swirler, wherein the plurality of injection holes and the first forward wall swirler is on outer radial wall swirlers is on a first side of the a second side ofthe plurality offuel injection holes, the plurality of fuel injection holes and the first forward first side being opposite the second side, wherein the wall swirler is on a second side of the plurality of fuel plurality of fuel injection holes are oriented perpen- 5 injection holes, the first side being opposite the second dicularly to the first axis.

side, wherein the plurality of fuel injection holes are 2. The mixer assembly of claim 1, wherein the first outer oriented perpendicularly to the first axis.

radial wall swirler further comprises a first plurality ofvanes 8. The mixer assembly of claim 7, wherein the plurality of forming a first plurality of air passages, wherein the first outer radial wall swirlers further comprises: plurality of vanes are oriented at an angle with respect to the io a first outer radial wall swirler comprising a first plurality first axis to cause air passing through the first outer radial of vanes forming a first plurality of air passages, wall swirler to rotate in a first direction; and wherein the first plurality of vanes are oriented at an the first forward wall swirler further comprises a second angle with respect to the first axis to cause air passing plurality of vanes forming a second plurality of air through the first outer radial wall swirler to rotate in a passages, wherein the second plurality of vanes are 15 first direction; and oriented at an angle with respect to the second axis to a second outer radial wall swirler comprising a second cause the air passing through the first forward wall plurality of vanes forming a second plurality of air swirler to rotate in a second direction.

passages, wherein the second plurality of vanes are 3. The mixer assembly of claim 2, wherein the first oriented at an angle with respect to the first axis to direction is opposite of the second direction. 20 cause the air passing through the second outer radial 4. The mixer assembly of claim 1, further comprising a wall swirler to rotate in a second direction.

pilot mixer, at least a portion of which is surrounded by the 9. The mixer assembly of claim 8, wherein the first main mixer, wherein the pilot mixer comprises an annular direction is opposite of the second direction.

housing having an outer surface that forms the annular inner 10. The mixer assembly of claim 8, wherein the plurality wall of the main mixer. 25 of outer radial wall swirlers further comprises a third outer 5. The mixer assembly of claim 1, further comprising a radial wall swirler comprising a third plurality of vanes fuel manifold in flow communication with the plurality of forming a third plurality of air passages, wherein the third fuel injection holes.

plurality of vanes are oriented at an angle with respect to the 6. The mixer assembly of claim 1, wherein the first side first axis to cause air passing through the third outer radial of the plurality of fuel injection holes is opposite of the 30 wall swirler to rotate in a third direction.

second side of the plurality of fuel injection holes.

11. The mixer assembly of claim 10, wherein the first 7. A mixer assembly for a gas turbine engine comprising: direction is the same as the third direction.

a main mixer comprising: 12. The mixer assembly of claim 7, wherein the first an annular inner radial wall; forward wall swirler further comprises a first plurality of an annular outer radial wall surrounding at least a portion 35 vanes forming a first plurality of air passages, wherein the of the annular inner radial wall, wherein the annular first plurality of vanes are oriented at an angle with respect outer radial wall incorporates a plurality of outer radial to the second axis to cause air passing through the first wall swirlers with a first axis oriented radially to a forward wall swirler to rotate in a fourth direction.

centerline axis of the mixer assembly; 13. The mixer assembly of claim 7, further comprising a a forward wall extending radially outward with respect to 40 second forward wall swirler proximate the first forward wall the first axis and connecting the annular inner radial swirler.

wall and the annular outer radial wall, the inner radial 14. The mixer assembly of claim 13, wherein the second wall, forward wall, and outer radial wall forming a forward wall swirler further comprises a second plurality of single annular cavity therebetween, wherein the for- vanes forming a second plurality of air passages, wherein the ward wall incorporates a first forward wall swirler with 45 second plurality of vanes are oriented at an angle with a second axis oriented axially to the centerline axis of respect to the second axis to cause air passing through the the mixer assembly; and second forward wall swirler to rotate in a fifth direction.

a plurality of fuel injection holes in the forward wall 15. The mixer assembly of claim 14, wherein the fourth between the plurality of outer radial wall swirlers and direction is opposite of the fifth direction.

the first forward wall swirler, the plurality of fuel 50 16. The mixer assembly of claim 7, wherein the first side injection holes oriented to inject a fuel into the main of the plurality of fuel injection holes is opposite of the mixer, wherein the fuel is atomized and dispersed by second side of the plurality of fuel injection holes.

airflow from the first outer radial wall swirler and is subsequently atomized and dispersed by airflow from