Patent Publication Number: US-10767865-B2

Title: Swirl stabilized vaporizer combustor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a non-provisional application of, and claims priority under 35 USC § 119(e) to, U.S. provisional application 62/349,309, filed Jun. 13, 2016, the entire contents of which are incorporated by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to combustors for gas turbine engines, and in particular to systems and methods associated with fuel vaporizer arrangements for use in combustors of gas turbine engines. 
     BACKGROUND 
     Gas turbine engines include a combustor where a mixture of fuel and air is ignited to complete a combustion process. Air is typically compressed by an upstream compressor system before being provided to the combustor. Fuel is typically provided by a fuel system, including, for example, an injector and/or a vaporizer fuel delivery device. After combustion, the combustor directs the combusted air to a downstream turbine through the discharge or turbine nozzle. Vaporizer fuel delivery devices may be preferred in some instance over high-pressure injector fuel system due to cost benefits as well as soot control and simpler control systems. Present approaches using a vaporizer fuel delivery system within combustors suffer from a variety of drawbacks, limitations, and disadvantages. There is a need for the inventive vaporizer fuel delivery arrangement, systems and methods disclosed herein. 
     BRIEF SUMMARY 
     Disclosed herein are examples of a gas turbine engine and a combustor with a fuel vaporizer. The combustor includes a combustor wall including an upstream wall portion interconnected between an inner wall structure and an outer wall structure to define a combustion chamber. A vaporizer tube is coupled to the combustor wall extending into the combustion chamber. The vaporizer tube includes a first end opening and a second end opening. A fuel injector having a nozzle may be extended within a portion of the vaporizer tube through the first end opening. A swirler is coupled to the upstream wall portion. A heat shield is disposed along the upstream wall portion, and surrounded by the swirler. The second end opening of the vaporizer tube is disposed over the heat shield to face the heat shield. The vaporizer tube may be shaped to place the second end opening over the heat shield. The fuel injector may have an outer cross-sectional area sized smaller than an inner cross-sectional area of the first end opening and the vaporizer tube to define a compressed air passageway into the vaporizer tube. The vaporizer tube may be disposed outside the periphery of the swirler. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments may be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale. Moreover, in the figures, like-referenced numerals designate corresponding parts throughout the different views. 
         FIG. 1  illustrates a gas turbine engine with a combustor. 
         FIG. 2  illustrates an example of a combustor. 
         FIG. 3  illustrates a perspective partial view of another example of a combustor. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein are examples of gas turbine engines and combustion systems that may be used in any industry, such as, for example, to power aircraft, watercraft, power generators, and the like. A fuel vaporizer system generally includes a vaporizer tube coupled to a pressurized fuel system. A mounting end of the vaporizer tube may mount to the wall of the combustor, allowing the tube to be immersed in the hot combustor. As a result, the air may be heated from the combustion process which aids in vaporizing the fuel and in pre-mixing the vaporized fuel with air. 
     A combustor including the fuel vaporizer system and a dome swirler system arrangement may have improved fuel-air mixing and combustion stability, especially in higher fuel-air ratio combination systems. The vaporizer tube may be configured to receive the fuel outside the dome swirler system and to deliver a fuel-air mixture inside the dome swirler system. For example, fuel-air mixture may exit the vaporizer tube to impinge against a heat shield that may be disposed at the central part of the dome swirler system. The heat shield may have a concaved body. The impinging fuel-air mixture may be then combined with the swirler toroidal recirculation air to become part of the primary zone recirculation in the combustor, which may provide improved mixing and stability characteristics required for engines operating at any fuel-air ratio, especially higher fuel-air ratios. This has been found as an improvement over vaporizer tube arrangements without a dome swirler that deliver fuel-air mixture in only a single-sided recirculation pattern within the combustor. 
     With reference to  FIG. 1  a gas turbine engine generally indicated at  10  includes, in axial flow series, an air intake  12 , a propulsive fan  14 , an intermediate pressure compressor  16 , a high pressure compressor  18 , combustion equipment  20 , turbine(s) (a high pressure turbine  22 , an intermediate pressure turbine  24 , a low pressure turbine  26 ) and an exhaust nozzle  28 . 
     The gas turbine engine  10  works in the conventional manner so that air entering the intake  12  is accelerated by the fan  14  to produce two air flows, a first air flow into the intermediate pressure compressor  16  and a second airflow which provides propulsive thrust. The intermediate pressure compressor  16  compresses the air flow directed into it before delivering the air to the high pressure compressor  18  where further compression takes place. 
     With additional reference to  FIG. 2 , the compressed air exhausted from the high pressure compressor  18  is directed into the combustion equipment  20  via a diffuser inlet  21  where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through and thereby drive the high, intermediate and low pressure turbines  22 ,  24  and  26  before being exhausted through the exhaust nozzle  28  to provide additional propulsive thrust. The high, intermediate and low pressure turbines  22 ,  24  and  26  respectively drive the high and intermediate pressure compressors  16  and  18  and the fan  14  by suitable interconnecting shafts. 
     Fuel may be directed into the combustor  30  through a number of fuel injectors located at the upstream end of the combustor  30 . The fuel injectors are circumferentially spaced around the engine  10  and serve to provide fuel into air derived from the high pressure compressor  18 . The resultant fuel and air mixture may be then combusted within the combustor  30 . 
     An outer casing  29  of the combustion equipment  20  surrounds the combustor  30  in a manner to define an annular plenum  40  there between. The combustor  30  has a combustor wall  31  including an annular combustor dome or upstream wall portion  42  interconnected between a tubular combustor inner wall structure  32  spaced from the outer casing  29  and a tubular combustor outer wall structure  34  spaced from the outer casing  29  to define different aspects of the plenum  40 . The inner wall structure  32  and the outer wall structure  34  each may be extended axially downstream along a longitudinal centerline (X-X) of the engine  10  from the upstream wall structure  42  towards the turbines, thereby defining a combustion chamber  45 . The combustion chamber  45  may be defined about a longitudinal centerline  35  of the combustor  30  positioned between the inner wall structure  32  and the outer wall structure  34 , which may be typically disposed along the longitudinal centerline (X-X) of the engine. The upstream wall portion  42 , the inner wall structure  32  and the outer wall structure  34  may be constructed as a multi-walled structure. For example, the inner wall structure and the outer wall structure may include a tubular shell layer, a tubular heat shield layer, and one or more cooling impingement cavities. Primary quench openings  48  may be formed in the inner and/or outer wall structures  32 ,  34  circumferentially around the longitudinal centerline (X-X) of the engine. The primary quench openings  48  formed in the inner and outer wall structures may be arranged to face one another. 
     The upstream wall portion  42  may include a swirler  50  to receive a portion (shown as B) of the compressed air exhausted from the high pressure compressor  18 . This B portion of compressed air enters into the swirler  50 , which generates turbulent flow for rapidly mixing the air with fuel. Another portion of the compressed air (shown as C) may be directed toward the annular plenum  40 , which will be used to maintain the combustion process and for cooling for a more uniform temperature profile at the combustion chamber exit. Another portion (shown as D) of the compressed air exhausted from the high pressure compressor  18  may be directed to a fuel vaporizer  80 . 
     The swirler  50  (also known as a dome swirler) may be coupled within an opening  51  formed in the upstream wall portion  42 . The swirler  50  may be defined by an annular body  53  including an inner band  52 , an outer band  54  defining the swirler periphery, and a plurality of swirler vanes  56  disposed in an annular arrangement between the bands  52 ,  54 . The vanes  56  are positioned within the annulus formed by the inner band  52  and the outer band  54  about a swirler axis SA that may be generally parallel, and in some examples, coaxially aligned with the longitudinal centerline  35  of the combustor. Each of the vanes  56  may be skewed relative to the swirler axis SA for swirling air traveling through the swirler  50  in a toroidal recirculation zone for improved mixing with fuel droplets exiting the fuel vaporizer  80 , thereby forming a fuel-air mixture M selected for operating the engine. In an example, the inner band  52 , outer band  54  and the swirler vanes  56  are integrally formed together as a unitary structure, for example, in the form of a casting. In one example, one or more of the inner band  52 , the outer band  54  and swirler vanes  56  are individually formed and assembled together, for example, by welding, to define the swirler  50 . The swirler  50  may be adapted to be an axial swirler or a radial swirler. The swirler  50  may be adapted to produce a swirled flow having a low pressure zone that forces some of the combustion products to recirculate in its core region to meet and mix with incoming fuel and air. 
     A fuel injector  58  may be included as a part of a fuel delivery system. Fuel may be supplied by various means such as, but not limited to, common rail, line or manifold  60  (as shown) that may be coupled to a fuel reservoir (not shown). Fuel exits the manifold  60 , enters into and exits from the fuel injector  58  and enters into the fuel vaporizer  80 . Fuel delivered from the fuel injector  58  to the fuel vaporizer  80  may be controlled via a fuel valve system (not shown) as part of the fuel system based the desired combustion efficiency, emissions, and operating conditions. The fuel injector  58  includes an injector housing  62 , a nozzle  64  and at least one fuel conduit  66  coupled to the manifold  60 . A base  68  of the injector housing  62  mounts the fuel injector  58  to a portion of the outer casing  29  and/or the upstream wall portion  42 . The injector housing  62  extends axially out from the fuel conduit  66 , through (or into) an injector port  69  formed in the outer casing  29 , to the nozzle  64 . A fuel port  70  may be provided in the nozzle  64  and may be fluidly coupled with the fuel conduit  66 . The nozzle  64  may be adapted to inject fuel through the fuel port  70  and into the fuel vaporizer  80  as described below in further detail, which may be in fluid communication with the D portion of compressed air. 
     The vaporizer  80  may be defined by a hollow tube  82  extending between a first end opening  86  and a second end opening  88 . The vaporizer tube  82  may be coupled to a portion of the combustor wall  31  to extend at least partially into the combustion chamber  45 . The hollow tube  82  may have a linear main trunk portion  84  extending downstream about a linear portion of a vaporizer axis VA, which may be in parallel with the centerline  35  of the combustor. In an example, the first end opening  86  (the inlet end) may be mounted to the upstream wall portion  42 . To this end, there may be a vaporizer tube port  72  formed in the upstream wall portion  42  and in alignment with the first end opening  86  of the tube  82 . One or more attachments (not shown) or bonding may be used to couple the vaporizer  80  to the fuel injector  58  (for example, the injector housing) and/or to the combustor  30  (for example, the upstream wall portion and/or the inner and/or outer wall structures). Examples of such attachment include, but are not limited to, a strut, a vane, a fastener, and a moveable joint such as, for example, a bushing or a bearing. Alternatively, examples of such bonding include, but are not limited to, for example, welding, brazing or adhering. 
     A portion of the fuel injector  58  extends through the first end opening  86  of the vaporizer tube  82  and resides within the main trunk portion  84 . The nozzle  64  of the fuel injector  58  may include the fuel port  70 , through which fuel exits the fuel injector  58  and enters into the vaporizer tube  82 . The main trunk portion  84  of the vaporizer tube  82  may be circumferentially aligned with the respective residing fuel injector  58 . In an example, the main trunk portion  84  of the vaporizer tube  82  may be coaxial with the nozzle  64  (for example, the fuel port  70 ) of the fuel injector  58 . In an example, the outer cross-sectional area of the nozzle  64  may be sized smaller than the inner cross-sectional area of the first end opening  86  and the main trunk portion  84  of the vaporizer tube  82  to define a compressed air passageway  89  therebetween that leads into the vaporizer  80 . In an example, a portion of the residing portion of the fuel injector may be attached to the inner wall of the tube  82  by the various attachment means already described herein to leave suitable space for the compressed air passageway  89 . 
     The first end opening  86  may be coaxial with the vaporizer axis VA or coextensive with an end of the main trunk portion  84 . One or more radial branch portions  90  may extend from the main trunk portion  84 . The radial branch portion  90  may be in fluid communication with the main trunk portion  84 , and may extend radially away from the linear portion of the vaporizer axis VA (or generally along a plane that may be generally perpendicular to the longitudinal centerline  35  of the combustor). In an example, the linear portion of the vaporizer axis VA may be offset from the longitudinal centerline  35  of the combustor, with the branch portion  90  extending radially toward the longitudinal centerline  35 . The branch portion  90  terminates in a manner such that an end of the branch portion  90  may be coextensive with the second end opening  88  (the outlet end) of the tube  82 . The second end opening  88  may be disposed downstream of the first end opening  86  and may be disposed to face upstream toward the upstream wall portion  42  in a spaced relationship from the upstream wall portion. Alternatively, the vaporizer tube  82  may be coupled to the inner or outer wall structures  32 ,  34  and extend radially toward the centerline  35  of the combustor to place the second end opening over the heat shield. 
     The main trunk and the branch portion(s)  84 ,  90  together may define the overall shape of the tube  82 , which may be defined as a L-shaped tube or a J-shaped tube having one outlet, T-shaped tube having two outlets, or other shapes having one or more outlets. The tube  82  shown in  FIG. 2  is a J-shaped tube where the branch portion  90  is fashioned as arcuate or more rounded or curved. Alternatively, the branch portion  90  of the tube may be fashioned more linearly, or substantially orthogonal (75 to 105 degrees), relative to the main trunk portion. Here, the tube may include an additional tip linear portion coextensive with the second end opening  88 , that may be fashioned more linearly, or substantially orthogonal (75 to 105 degrees) relative to the branch portion or substantially parallel (plus or minus 10 degrees) relative to the main trunk portion  84 . 
     The D portion of compressed air enters through the compressed air passageway  89  of the vaporizer tube  82 , mixes with fuel exiting the fuel port  70  of the fuel injector  58  to define a fuel-air mixture M, and passes into the interior of the combustion chamber  45  through the second end opening  88  of the vaporizer tube  82 . As the fuel-air mixture M passes within the lumen of the vaporizer tube  82 , the fuel absorbs heat from the vaporizer tube  82  and may be vaporized to define the fuel-air mixture M. Since the vaporizer  80  may be susceptible to high heat loads from the combustion process, the vaporization of the fuel may help cool the vaporizer, as well as cooling from the D portion of compressed air flowing through the interior of the vaporizer tube. Cooling may also be provided from the fuel from the nozzle being directed at the internal surface of the vaporizer tube. 
     A heat shield  100  may be included along the combustor to protect portions of the combustor wall from the hot burner gases and from an unacceptably high radiation effect from the combustion process. The heat shield  100  may be included along the upstream wall portion  42  of the combustor  30 . Impinging fuel-air mixture M may be adapted to cool the heat shield  100 . The heat shield  100  may be adapted to direct or deflect radially, downstream, or a combination of both the fuel-air mixture M after impingement toward the swirler  50 . After impingement, the fuel-air mixture M may be combined with the B portion of compressed air exiting the swirler  50  to become part of the primary zone recirculation. The second end opening  88  of the vaporizer tube  82  may be oriented over the heat shield  100  in order to provide the impinging fuel-air mixture M exiting the vaporizer  80  directly against the heat shield  100 . The heat shield  100  and the second end opening  88  of the vaporizer tube  82  may be arranged such that the fuel-air mixture M exiting the tube  82  impinges along an intermediate zone or at a central zone of the heat shield  100 . In an example, the body of the heat shield  100  may include an outer periphery  102 , which may be in a circular form, defined about a heat shield axis DA extending at the center of the heat shield body. Here, the heat shield axis DA may be coaxial with a second vaporizer axis OA at the second end opening  88  of the vaporize tube  82 . 
     The heat shield  100  may have various shapes to encourage or be adapted for the radial outward and/or downstream circulation of fuel-air mixture M. In an example, the body of the heat shield  100  may have a concave or bowl shape to define a concaved heat shield body. The heat shield  100  may project or protrude upstream from the upstream wall portion  42  of the combustor  30 . In an example, the heat shield  100  may be shaped as a circular bowl. In an example, the heat shield  100  may be disposed along a central part of the swirler  50 . In an example, when the heat shield  100  is circular about the heat shield axis DA, the heat shield axis DA may be coaxial with the swirler axis SA. In an example, the swirler and heat shield may be located generally about the central area of the upstream wall portion  42  such that the heat shield axis DA, the swirler axis SA, the second vaporizer axis OA, or any combination thereof, may be coaxial with the longitudinal centerline  35  of the combustor. 
     The swirler  50  may be defined as including the heat shield  100 . In an example, the heat shield  100  may be formed integrally with the swirler  50  as a single unit, such as, for example, by a casting process, by which the single unit may be then mounted into an aperture formed in the upstream wall portion  42 . Alternatively, the body of the heat shield  100 , such as, for example, a central concaved body, may be coupled to the surrounding annulus body of the swirler  50  to define a single assembly, which may be then mounted into an aperture formed in the upstream wall portion  42 . One or more attachments (not shown) or bonding may be used to couple the heat shield to the swirler and/or to the combustor (for example, the upstream wall structure and/or the inner and/or outer wall structures). Examples of such attachment include, but are not limited to, a strut, a vane, a fastener, and a moveable joint such as, for example, a bushing or a bearing. Alternatively, examples of such bonding include, but are not limited to, for example, welding, brazing or adhering. 
     During operation of the gas turbine engine of  FIG. 2 , the combustor plenum  40  receives compressed air (shown as A) from the high pressure compressor. Some of the air will be provided to the combustor  30  from the plenum  40  for the combustion process. For example, some of the air (the D portion of compressed air) within the plenum  40  may be directed through the vaporizer  80  for mixing with the fuel dispensed by the fuel injectors to provide the fuel-air mixture M. As a result of the combustion process, thermal energy may be released which may radiate upstream through the combustion chamber  45  to heat the vaporizer  80  to vaporize some or substantially all of the fuel dispensed against the heated surface of the vaporizer tube. The fuel-air mixture M may be ignited within the combustion chamber  45 , for example by one or more igniters (not shown), to power the gas turbine engine. Fuel-air mixture M exiting the vaporizer  80  impinges against the heat shield  100  that may be adapted to redirect the impinging fuel-air mixture M radially outward and/or downstream toward the swirler  50 . The impinging fuel-air mixture M may be then combined with the B portion of compressed air being formed into a toroidal recirculation air to become part of the primary zone recirculation in the combustor. The primary quench openings  48  may direct additional air (the C portion of compressed air) from the plenum  40  into the combustion chamber  45  downstream of the vaporizer  80  for controlling the fuel-air mixture and/or cooling the combusted air prior to be introduced to the turbines. 
       FIG. 3  depicts a partial view of another example of the combustor configuration which could be included in the gas turbine engine  10 . Here, the combustor  130  includes multiple swirlers, heat shields, vaporizer tubes (only one shown), or any combination thereof, similar to what is described above with respect to  FIG. 2 . In an example,  FIG. 3  depicts the combustor  130  including a first swirler  150  and a corresponding first heat shield  200  and a second swirler  151  and a corresponding second heat shield  201  disposed along the upstream wall portion  142  between the inner wall structure and the outer wall structure (not shown). Each set of a combination of the swirler and the heat shield may include its own fuel vaporizer, similar to what is described above. Alternatively, each set of a combination of the swirler and the heat shield may share a common fuel vaporizer  180 , as shown in  FIG. 3 . In an example, the combustor  130  may be further configured to include multiple sets of the combination of the swirlers and heat shields and the vaporizer tubes spaced equally around a circumference of the upstream wall portion in the shape of an annulus. 
     The fuel vaporizer tube  182  may be coupled to the tube port  172  formed in the upstream wall portion  142  radially outside of both of (or in between) the first swirler  150  and the second swirler  151 . The vaporizer tube  182  may be shaped to place a first  188 A of the second end openings over the first heat shield  200 , for example, over a central zone of the first heat shield  200 , and to place a second  188 B of the second end openings over the second heat shield  201 , for example, a central zone of the second heat shield  201 , with the second end openings  188 A,  188 B facing the respective first and second heat shields  200 ,  201 . 
     In an example, the vaporizer tube  182  may be defined by a main trunk portion  184  extending from the upstream wall portion  142  into the combustion chamber (not shown). In an example, the main trunk portion  184  may be extended along the longitudinal centerline of the combustor. The tube  182  may be also defined by a first branch portion  190  and a second branch portion  191  extending radially away from the main trunk portion  184 . To this end, the main trunk portion  184  terminates into, while maintaining fluid communication with, the inlet ends of the first and second branch portions  190 ,  191 . An inlet end of the main trunk portion  184  may be coextensive with the first end opening  186  of the tube  182 . An outlet end of the first branch portion  190  may be coextensive with the first  188 A of the second end openings, while an outlet end of the second branch portion  191  may be coextensive with the second  188 B of the second end openings. The branch portions  190 ,  191  may extend along a plane that may be generally perpendicular to the longitudinal centerline of the combustor. Internal baffles and flow dividers (not shown) may be included within the vaporizer tube  182 , for example in close proximity to the intersection of the main trunk portion and the radial branch portions, to improve mixing of the fuel and air mixture and for equally dividing the fuel and air mixture entering into the branch portions. 
     Operation here would be similar to what is described above. For example, some of the air within the combustor plenum may be directed through the vaporizer  180  for mixing with the fuel dispensed by the fuel injectors to provide the fuel-air mixture. Fuel-air mixture exiting the second openings  188 A.  188 B of the vaporizer tube  182  impinges against the corresponding heat shields  200 ,  201 . 
     To clarify the use of and to hereby provide notice to the public, the phrases “at least one of &lt;A&gt;, &lt;B&gt;, . . . and &lt;N&gt;” or “at least one of &lt;A&gt;, &lt;B&gt;, &lt;N&gt;, or combinations thereof” or “&lt;A&gt;, &lt;B&gt;, . . . and/or &lt;N&gt;” are defined by the Applicant in the broadest sense, superseding any other implied definitions hereinbefore or hereinafter unless expressly asserted by the Applicant to the contrary, to mean one or more elements selected from the group comprising A, B, . . . and N. In other words, the phrases mean any combination of one or more of the elements A, B, . . . or N including any one element alone or the one element in combination with one or more of the other elements which may also include, in combination, additional elements not listed. 
     While various embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible. Accordingly, the embodiments described herein are examples, not the only possible embodiments and implementations. 
     Furthermore, the advantages described above are not necessarily the only advantages, and it is not necessarily expected that all of the described advantages will be achieved with every embodiment.