Abstract:
A combustor for a gas turbine engine that includes first and second combustion chambers interconnected by a throat region that includes a converging wall section, a diverging wall section, and a throat apex between the diverging wall section and the converging wall section; a plurality of cooling apertures disposed on the converging wall section; and a cooling slot disposed on the diverging wall section; wherein: the cooling apertures comprise apertures through the thickness of the converging wall section; and the cooling slot comprising a circumferentially extending slot through the length of the diverging wall section.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This present application relates generally to systems and/or apparatus for improving the efficiency and/or operation of turbine engines and/or industrial machinery, which, as used herein and unless specifically stated otherwise, is meant to include all types of combustion turbine or rotary engines, including gas turbine engines, aircraft engines, and others. More specifically, but not by way of limitation, the present application relates to methods, systems, and/or apparatus pertaining to combustor cooling and operation in gas turbine engines. 
         [0002]    During operation of a gas turbine engine, combustion of fuel and compressed air mixture occurs inside a combustor. To prevent damage to the turbine or other parts of the gas turbine engine, the combustion process is stabilized to contain the process inside the combustor. Typically, a venturi is provided inside a combustion chamber of the combustor. A venturi substantially stabilizes the combustion process and prevents the flame from flashing backwards into other parts of the turbine engine. Further, various components of the combustor, especially walls of the combustion chamber and the venturi, require cooling to prevent damage and also, to increase the life of the components. 
         [0003]    Over the years, different methods and systems have been used to provide cooling to various components of the combustor. This may include a liner, which circumferentially surrounds the combustion chamber and accepts a flow of a coolant. The coolant flowing through the liner may only provide surface cooling to the combustion chamber and the venturi. However, surface cooling may not be effective in cooling the combustion chamber and the venturi, which results in a reduced life for the combustor. Further, the coolant flowing through the liner may substantially include compressed air diverted from a compressor of the gas turbine engine. The compressed air, after performing the cooling operation, is discarded in an aft portion of the liner, which may reduce an efficiency of the gas turbine engine. Moreover, the venturi used in this type of cooling configuration may include more number of components and thus, involves a complicated construction. 
         [0004]    Further, to reduce wastage of compressed air from the compressor, the compressed air may be introduced inside the combustion chamber, after performing cooling. However, such a configuration may further complicate the construction of the venturi and/or the combustion chamber and only provide a surface cooling of the parts of the combustor. 
         [0005]    As a result, there is a need for improved systems and apparatus relating to the more efficient and cost effective cooling of the combustors in a gas turbine engines. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0006]    The present application, thus, describes a venturi for use in a combustor of a gas turbine engine, the venturi comprising two non-integrally formed pieces: a forward piece and an aft piece; wherein: the forward piece comprises a forward axial extension, a converging wall section, and a diverging outer-wall section; the aft piece comprises an aft axial extension and a diverging inner-wall section; and the forward piece and the aft piece are configured such that the diverging inner-wall section resides in close, spaced relation to the diverging outer-wall section such that a circumferentially extending cooling slot is formed therebetween. 
         [0007]    The present application further describes a combustor for a gas turbine engine that includes first and second combustion chambers interconnected by a throat region that includes a converging wall section, a diverging wall section, and a throat apex between the diverging wall section and the converging wall section; a plurality of cooling apertures disposed on the converging wall section; and a cooling slot disposed on the diverging wall section; wherein: the cooling apertures comprise apertures through the thickness of the converging wall section; and the cooling slot comprising a circumferentially extending slot through the length of the diverging wall section. 
         [0008]    These and other features of the present application will become apparent upon review of the following detailed description of the preferred embodiments when taken in conjunction with the drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    These and other features of this invention will be more completely understood and appreciated by careful study of the following more detailed description of exemplary embodiments of the invention taken in conjunction with the accompanying drawings, in which: 
           [0010]      FIG. 1  is a partial cross-sectional view of a conventional combustor; 
           [0011]      FIG. 2  is a partial cross-sectional view of a combustor, according to an exemplary embodiment of the present application; 
           [0012]      FIG. 3  is a cross-sectional view of a venturi with at least two non-integrally formed pieces, according to an exemplary embodiment of the present application; 
           [0013]      FIG. 4  is a cross-sectional view of the venturi with one or more turbulators on a diverging inner-wall section, according to an exemplary embodiment of the present application; 
           [0014]      FIG. 5  is a cross-sectional view of the venturi with cooling apertures on the diverging inner-wall section, according to an exemplary embodiment of the present application; and 
           [0015]      FIG. 6  is a cross-sectional view of the venturi with an integral construction, according to an exemplary embodiment of the present application. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    As an initial matter, to communicate clearly the invention of the current application, it may be necessary to select terminology that refers to and describes certain parts or machine components of a combustion turbine engine. Whenever possible, common industry terminology will be used and employed in a manner consistent with its accepted meaning. However, it is meant that any such terminology be given a broad meaning and not narrowly construed such that the meaning intended herein and the scope of the appended claims is unreasonably restricted. Those of ordinary skill in the art will appreciate that often a particular component may be referred to using several different terms. In addition, what may be described herein as a single part may include and be referenced in another context as consisting of several component parts, or, what may be described herein as including multiple component parts may be fashioned into and, in some cases, referred to as a single part. As such, in understanding the scope of the invention described herein, attention should not only be paid to the terminology and description provided, but also to the structure, configuration, function, and/or usage of the component, as provided herein. 
         [0017]    In addition, several descriptive terms may be used regularly herein, and it may be helpful to define these terms. These terms and their definitions, as used herein, are as follows. As used herein, “downstream” and “upstream” are terms that indicate a direction relative to the flow of a working fluid through the turbine. As such, the term “downstream” refers to a direction that generally corresponds to the direction of the flow of the working fluid, and the term “upstream” generally refers to the direction that is opposite of the direction of flow of the working fluid. The terms “forward” and “aft”, without any further specificity, refer to directions, with “forward” referring to the forward or compressor end of the engine and “aft” referring to the aft or turbine end of the engine. The term “radial” refers to movement or position perpendicular to an axis. It is often required to describe parts that are at differing radial positions with regard to an axis. In this case, if a first component resides closer to the axis than a second component, it may be stated herein that the first component is “radially inward” or “inboard” of the second component. If, on the other hand, the first component resides further from the axis than the second component, it may be stated herein that the first component is “radially outward” or “outboard” of the second component. The term “axial” refers to movement or position parallel to an axis. Finally, the term “circumferential” refers to movement or position around an axis. 
         [0018]    Referring now to the figures, where the various numbers represent like parts throughout the several views,  FIG. 1  illustrates a partial cross-sectional view of a conventional combustor  100  of a gas turbine engine (not shown). The combustor  100  may include a venturi  102  and an axial portion  104 . The venturi  102  may include an inner venturi portion  106  and an outer venturi portion  108 . Also, the axial portion  104  of the combustor  100  may include an inner wall  110  and an outer wall  112 . Further, a circumferential liner  114  may be formed between the inner and outer venturi portions  106  and  108 , and the inner wall  110  and the outer wall  112 . During a cooling process, a coolant may enter the liner  114  through multiple holes  116  that are provided in the outer venturi portion  108 . The coolant may then flow through the liner  114  and substantially performs impingement cooling on the venturi  102 . However, impingement cooling may only result in surface cooling, which may be ineffective at cool the venturi  102 , and thus, the life of the component may be reduced. Moreover, improper cooling of the venturi  102  may also lead to an auto ignition of the fuel. Additionally, the coolant, after performing the cooling operation, may be discarded in an aft portion (not shown) of the liner  114 , which may further reduce the efficiency of the gas turbine engine. 
         [0019]    Further, the coolant may include coolant air that is diverted from combustor air, which is compressed in a compressor (not shown) and utilized for combustion. Thus, coolant air, which may form a significant part of combustor air, also reduces an efficiency of the gas turbine engine. Moreover, the venturi  102  may also include a large number of components and thus, involves a complicated construction because of the inner and outer venturi portions  106  and  108 . 
         [0020]      FIG. 2  illustrates a partial cross-sectional view of an exemplary combustor  200  of the gas turbine engine, according to an embodiment of the present application. Those of ordinary skill in the art will appreciate that the present application is not limited to this type of usage and may be used in other types of combustion turbine or rotary engines, such as, but not limited to, aircraft engines, power generation engines, steam turbine engines and the like.  FIG. 2  illustrates an upper half of the combustor  200  for clarity. The combustor  200  may be substantially symmetric about a central axis A. Combustion of a combustor air and fuel mixture may occur inside the combustor  200 . Subsequent to compression in the compressor, combustor air may be introduced at a head end (not shown) of the combustor  200  and fuel may be introduced in the combustor air to form the combustor air and fuel mixture. 
         [0021]    The combustor  200  may include an inlet (not shown) for the entry of the combustor air and fuel mixture into a combustion chamber  208 . In various embodiments of the present application, the combustor  200  may include one or more inlets. One or more ignition means (E.g. spark plugs) may be provided in the combustion chamber  208  to ignite the combustor air and fuel mixture. Subsequent to ignition, combustion products may exit the combustor  200  to a turbine (not shown). A venturi  210  may be provided inside the combustion chamber  208  to substantially stabilize in order to contain the ignition of the combustor air and fuel mixture inside the combustor  200 . In an embodiment of the present application, a divergence step  211  may be provided downstream of the venturi  210  to substantially mitigate a screech of the combustor air and fuel mixture. As shown, the venturi  210  may substantially divide the combustion chamber into a first stage combustion chamber  212  and a second stage combustion chamber  214 . 
         [0022]    Further, a flow sleeve  216  may be provided to form a coolant plenum  218  between the flow sleeve  216  and a combustion chamber wall  220 . The coolant plenum  218  may be disposed circumferentially around the combustor chamber  208 . In an embodiment of the present application, the coolant plenum  218  may be configured to receive a flow of pressurized coolant through a flow sleeve inlet  222 . In an embodiment of the present application, the pressurized coolant may be pressurized air diverted from the compressor. In another embodiment of the present application, the pressurized coolant may be pressurized air mixed with water, steam or inert gas. The pressurized coolant may flow through the coolant plenum  218  and exit the coolant plenum  218  through a flow sleeve outlet  224 . Those of ordinary skill in the art will appreciate that the pressurized coolant may also flow in a direction opposite to the direction illustrated in  FIG. 2  without deviating from the scope of the present application. 
         [0023]      FIG. 3  illustrates a more detailed, non-scaled cross-sectional view of the venturi  210 , in which coolant channels according to an exemplary embodiment of the present application are more clearly shown. In an embodiment of the present application, the venturi  210  may include a forward piece  302  and an aft piece  304 . As illustrated in  FIG. 2 , the forward piece  302  and the aft piece  304  may be non-integrally formed. However, the venturi  210  may include more than two non-integrally formed pieces. In an embodiment of the present application, the forward piece  302  may include a forward axial extension  306 , a converging wall section  308 , and a diverging outer-wall section  310 , while the aft piece  304  may include an aft axial extension  312  and a diverging inner-wall section  314 . In an embodiment of the present application, the forward piece  302  and the aft piece  304  may be configured such that the diverging inner-wall section  314  reside in close, spaced relation with respect to the diverging outer-wall section  310 . This may form a circumferentially extending cooling slot  316  (hereinafter referred to as “the cooling slot  316 ”) between the diverging outer-wall section  310  and the diverging inner-wall section  314 . In an alternative embodiment of the present application (not shown), the forward piece  302  and the aft piece  304  may be configured such that the forward piece  302  includes the diverging inner-wall section  314  and the aft piece  304  includes the diverging outer-wall section  310 . 
         [0024]    As illustrated in  FIG. 3 , the pressurized coolant flowing through the coolant plenum  218  may enter the combustion chamber  208  via the cooling slot  316 . This may result in a substantially volumetric cooling of the venturi  210 . Volumetric cooling may provide an improved cooling of the venturi  210  and prolong the life of the venturi  210 . Further, volumetric cooling may also substantially prevent auto ignition of fuel inside the first stage combustion chamber  212 . In various embodiments of the present application, the cooling slot  316  may also include turbulators and/or cooling apertures (described in conjunction with  FIGS. 4 and 5  respectively) to enhance the cooling of the venturi  210 . Further, the pressurized coolant, which enters the combustion chamber  208  and substantially includes pressurized air from the compressor, is utilized for combustion. This may substantially reduce wastage of pressurized air flowing through the coolant plenum  218  and also increases an efficiency of the gas turbine engine. Further, an amount of pressurized air, which is left after cooling, may be utilized for other purposes, such as, but not limited to, reducing pollutants like NOx, CO, and the like. In various embodiments of the present application, reduction in pollutants may be achieved by introducing the pressurized air, left after cooling, at the head-end of the combustor  200 . In addition, the venturi  210  of the present application may require a lower number of components and, as such, present a simplified one or two-piece construction. 
         [0025]    As illustrated in  FIG. 3 , the diverging outer-wall section  310  may include an inner face  318  that faces the cooling slot  316  and an outer face  320  that faces the coolant plenum  218 . Further, the diverging inner-wall section  314  may include an outer face  322  that faces the cooling slot  316  and an inner face  324  that faces the second stage combustion chamber  214 . Thus, the inner face  318  of the diverging outer-wall section  310  may oppose the outer face  322  of the diverging inner-wall section  314  across the cooling slot  316 . In an embodiment of the present application, the forward piece  302  may be configured such that the forward axial extension  306  extends axially along an approximate outer radial position of the combustor  200  from a forward end  326  to an aft end  328 . The approximate outer radial position of the combustor  200  may correspond substantially to a radial position of the combustion chamber wall  220 . Further, the converging wall section  308  may extend diagonally inward substantially from the aft end  328  of the forward axial extension  306  to a throat apex  330 . A radial position of the throat apex  330  may correspond to a constriction of the venturi  210 , which accelerates the flow of the combustor air and fuel mixture. Additionally, the diverging outer-wall section  310  may extend diagonally outward substantially from the throat apex  330  to an end  332  corresponding to the approximate radial outer position of the combustor  200 . In an embodiment of the present application, the aft piece  304  is configured such that the aft axial extension  312  may extend axially along the approximate outer radial position of the combustor  200  from a forward end  334  to an aft end  336 . Further, the diverging inner-wall section  314  may extend diagonally inward substantially from the forward end  334  of the aft axial extension  312  to an end  338 . The end  338  may be located at a position which is proximate to the throat apex  330 . 
         [0026]    In an embodiment of the present application, the cooling slot  316  may include a mouth  340 , which is defined between the end  332  of the outer-wall section  310  and a section of the aft piece  304  where the aft axial extension  312  transitions to the diverging inner-wall section  314 . Such a section of the aft piece  304  may be proximate to the forward end  334  of the aft axial extension  312 . In an embodiment of the present application, the cooling slot  316  may include an outlet  342  defined between the end  338  of the diverging inner-wall section  314  of the aft piece  304  and the throat apex  330  of the forward piece  302 . In various embodiments of the present application, at least one of the sections of the forward piece  302  or the aft piece  304  where the forward axial extension  306  or the aft axial extension  312  transitions to the converging wall section  308  or the diverging inner wall section  314  may be chamfered or filleted. 
         [0027]    As illustrated in  FIG. 3 , the converging wall section  308  may include an inner face  344  that faces the first stage combustion chamber  212  and an outer face  346  that faces the coolant plenum  218 . In an embodiment of the present application, the converging wall section  308  may include multiple cooling apertures  348 . As illustrated in  FIG. 3 , each of the cooling apertures  348  may originate on the outer face  346  and extend through the thickness of the converging wall section  308  to an opening on the inner face  344 . Thus, the cooling apertures  348  may provide additional passageways for the pressurized coolant from the coolant plenum  218  to the combustion chamber  208 . Thus, the cooling apertures  348  may further enhance cooling of the forward piece  302  of the venturi  210 . In an embodiment of the present application, at least one of the cooling apertures  348  may be of a substantially cylindrical shape. However, other shapes of the cooling apertures  348  may be possible without departing from the scope of the present application. 
         [0028]    In an embodiment of the present application, the cooling apertures  348  may be configured such that each of the cooling apertures  348  is approximately perpendicular to the inner face  344  and the outer face  346  of the converging wall section  308 . In an alternative embodiment of the present application, the cooling apertures  348  may be obliquely oriented with respect to the inner face  344  and the outer face  346  of the converging wall section  308 . In an embodiment of the present application, the cooling apertures  348  on the converging wall section  308  may be arranged in multiple circumferentially extending rows. However, the cooling apertures  348  on the converging wall section  308  may be arranged in any other configuration (E.g. staggered) without deviating from the scope of the present application. 
         [0029]    In an embodiment of the present application, the cooling apertures  348  may be configured such that each of the cooling apertures  348  is approximately perpendicular to the inner face  344  and the outer face  346  of the converging wall section  308 . In an alternative embodiment of the present application, the cooling apertures  348  may be tilted with respect to the centerline A-A shown in  FIG. 2 . It will be appreciated that this will produce a performance-enhancing swirl about the centerline in the pressurized coolant flowing through apertures  348 . 
         [0030]      FIG. 4  illustrates a detailed cross-sectional view of the exemplary venturi  210 , according to an embodiment of the present application. As illustrated in  FIG. 4 , the outer face  322  of the diverging inner-wall section  314  may include one or more turbulators  402 . Those of ordinary skill in the art will appreciate that the turbulators  402  may be provided on the inner face  318  of the diverging outer-wall section  310  without departing from the scope of the present application. Turbulators  402  on the outer face  322  of the diverging inner-wall section  314  may cause turbulence in the pressurized coolant flowing through the cooling slot  316 , and thus, enhances cooling of the aft piece  304  of the venturi  210 . As illustrated in  FIG. 4 , the turbulators  402  may have a substantially rectangular cross-section. However, the turbulators  402  may have any other cross-section, such as, but not limited to, circular, elliptical, polygonal, or the like. 
         [0031]      FIG. 5  illustrates a detailed cross-sectional view of the exemplary venturi  210 , according to another embodiment of the present application. As illustrated in  FIG. 5 , the diverging inner-wall section  314  may include multiple cooling apertures  502 . Each of the cooling apertures  502  may originate on the outer face  322  and extend through the thickness of the diverging inner-wall section  314  to an opening on the inner face  324 , and thus, creates a passageway for the pressurized coolant through the diverging inner-wall section  314 . Thus, the cooling apertures  502  may further enhance cooling of the aft piece  304  of the venturi  210 . In an embodiment of the present application, at least one of the cooling apertures  502  may be of a substantially cylindrical shape. Those of ordinary skill in the art will appreciate that other shapes of the cooling apertures  502  may be possible without departing from the scope of the present application. 
         [0032]    In an embodiment of the present application, the cooling apertures  502  may be configured such that each of the cooling apertures  502  is approximately perpendicular to the inner face  324  and the outer face  322  of the diverging inner-wall section  314 . In an alternative embodiment of the present application, the cooling apertures  502  may be tilted with respect to the centerline A-A shown in  FIG. 2 . It will be appreciated that this will produce a performance-enhancing swirl about the centerline to the pressurized coolant flowing through apertures  502 . 
         [0033]    In an embodiment of the present application, the cooling apertures  502  may be configured such that each of the cooling apertures  502  is approximately perpendicular to the inner face  324  and the outer face  322  of the diverging inner-wall section  314 . In an alternative embodiment of the present application, the cooling apertures  502  may be obliquely oriented with respect to the inner face  324  and the outer face  322  of the diverging inner-wall section  314 . In an embodiment of the present application, the cooling apertures  502  on the diverging inner-wall section  314  may be arranged in multiple circumferentially extending rows. However, the cooling apertures  502  on the diverging inner-wall section  314  may be arranged in any other configuration (E.g. staggered) without deviating from the scope of the present application. 
         [0034]      FIG. 6  illustrates a detailed cross-sectional view of the exemplary venturi  210 , according to another exemplary embodiment of the present application. As illustrated in  FIG. 6 , the venturi  210  may be of an integral construction with a forward portion  602  and an aft portion  604 . Further, the forward portion  602  may include multiple cooling apertures  606 . In an embodiment of the present application, the aft portion  604  may include multiple through holes  608 . Particularly, only one through hole  608  is visible in  FIG. 6 , other through holes  608  may be arranged circumferentially in the aft portion  604 . The pressurized coolant may flow though the cooling apertures  606  and the through hole  608  to result in a volumetric cooling of the venturi  210 . 
         [0035]    As one of ordinary skill in the art will appreciate, the many varying features and configurations described above in relation to the several exemplary embodiments may be further selectively applied to form the other possible embodiments of the present invention. For the sake of brevity and taking into account the abilities of one of ordinary skill in the art, all of the possible iterations is not provided or discussed in detail, though all combinations and possible embodiments embraced by the several claims below or otherwise are intended to be part of the instant application. In addition, from the above description of several exemplary embodiments of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are also intended to be covered by the appended claims. Further, it should be apparent that the foregoing relates only to the described embodiments of the present application and that numerous changes and modifications may be made herein without departing from the spirit and scope of the application as defined by the following claims and the equivalents thereof.