Abstract:
The present application provides an impingement cooling system for use with a contoured surface. The impingement cooling system may include an impingement plenum and an impingement plate with a linear shape facing the contoured surface. The impingement surface may include a number of projected area thereon with a number of impingement holes having varying sizes and varying spacings.

Description:
TECHNICAL FIELD 
       [0001]    The present application and the resultant patent relate generally to gas turbine engines and more particularly relate to an impingement cooling system for uniformly cooling contoured surfaces in a gas turbine and elsewhere in a simplified design. 
       BACKGROUND OF THE INVENTION 
       [0002]    Impingement cooling systems have been used with turbine machinery to cool various types of components such as casings, buckets, nozzles, and the like. Impingement cooling systems cool the turbine components via an airflow so as to maintain adequate clearances between the components and to promote adequate component lifetime. One issue with known impingement cooling systems is the ability to maintain a uniform heat transfer coefficient across non-uniform or contoured surfaces. Maintaining constant heat transfer coefficients generally requires that the overall shape of the impingement plate follows the contours of the surface to be cooled. Producing a contoured impingement plate, however, may be costly and may result in uneven cooling flows therein. 
         [0003]    There is therefore a desire for an improved impingement cooling system. Such an improved impingement cooling system may provide constant heat transfer coefficients over a contoured surface in a simplified and low cost configuration while maintaining adequate cooling efficiency. 
       SUMMARY OF THE INVENTION 
       [0004]    The present application and the resultant patent thus provide an impingement cooling system for use with a contoured surface. The impingement cooling system may include an impingement plenum and an impingement plate with a linear shape facing the contoured surface. The impingement plate may include a number of projected areas thereon with a number of impingement holes having varying sizes and varying spacings. 
         [0005]    The present application and the resultant patent further provide a turbine. The turbine may include a turbine nozzle, an impingement cooling system with a number of impingement holes with a number of sizes and spacings, and a turbine component with a contoured surface positioned about the impingement cooling system. 
         [0006]    The present application and the resultant patent further provide a turbine. The turbine may include a turbine nozzle, an impingement cooling system with a linear shape and having a number of impingement holes with a number of sizes and spacings, and a turbine component with a contoured surface positioned about the impingement cooling system such that the impingement cooling system maintains the contoured surface with substantially constant heat transfer coefficients thereacross. 
         [0007]    These and other features and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic diagram of a gas turbine engine showing a compressor, a combustor, and a turbine. 
           [0009]      FIG. 2  is a partial side view of a nozzle vane with an impingement cooling system therein. 
           [0010]      FIG. 3  is a partial side view of a nozzle vane with an impingement cooling system as may be described herein. 
           [0011]      FIG. 4  is a perspective view of an impingement grid overlaid on the contoured surface of  FIG. 3 . 
           [0012]      FIG. 5  is a plan view of a portion of the impingement cooling plate of  FIG. 3 . 
           [0013]      FIG. 6  is a plan view of a portion of the impingement cooling plate of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring now to the drawings, in which like numerals refer to like elements throughout the several views,  FIG. 1  shows a schematic view of gas turbine engine  10  as may be used herein. The gas turbine engine  10  may include a compressor  15 . The compressor  15  compresses an incoming flow of air  20 . The compressor  15  delivers the compressed flow of air  20  to a combustor  25 . The combustor  25  mixes the compressed flow of air  20  with a pressurized flow of fuel  30  and ignites the mixture to create a flow of combustion gases  35 . Although only a single combustor  25  is shown, the gas turbine engine  10  may include any number of combustors  25 . The flow of combustion gases  35  is in turn delivered to a turbine  40 . The flow of combustion gases  35  drives the turbine  40  so as to produce mechanical work. The mechanical work produced in the turbine  40  drives the compressor  15  via a shaft  45  and an external load  50  such as an electrical generator and the like. 
         [0015]    The gas turbine engine  10  may use natural gas, various types of syngas, and/or other types of fuels. The gas turbine engine  10  may be any one of a number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y., including, but not limited to, those such as a 7 or a 9 series heavy duty gas turbine engine and the like. The gas turbine engine  10  may have different configurations and may use other types of components. Other types of gas turbine engines also may be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation equipment also may be used herein together. 
         [0016]      FIG. 2  is an example of a nozzle  55  that may be used with the turbine  40  described above. Generally described, the nozzle  55  may include a nozzle vane  60  that extends between an inner platform  65  and an outer platform  70 . A number of the nozzles  55  may be combined into a circumferential array to form a stage with a number of rotor blades (not shown). The nozzle  55  also may include an impingement cooling system in the form of an impingement plenum  80 . The impingement plenum  80  may have a number of impingement apertures  85  formed therein. The impingement plenum  80  may be in communication with a flow of air  20  from the compressor  15  or another source via a cooling conduit  90 . The flow of air  20  flows through the nozzle vane  60 , into the impingement plenum  80 , and out via the impingement apertures  85  so as to impingement cool a portion of the nozzle  55  or elsewhere. Other types of impingement plenums  80  are known. 
         [0017]    Many other types of impingement cooling systems are known. These known impingement cooling systems, however, generally are uniformly sized and shaped as described above. Alternatively, the impingement plate may be contoured so as to follow the contours of the surface to be cooled so as to maintain constant heat transfer coefficients across the surface. 
         [0018]      FIG. 3  and  FIG. 4  show an example of an impingement cooling system  100  as may be described herein. The impingement cooling system  100  may include an impingement plenum  110 . The impingement plenum  110  may include a cavity  120  defined by an impingement plate  130  and a cover plate  140 . The impingement plenum  110  may be in communication with a cooling flow  150  via a cooling conduit  160 . The cooling conduit  160  may be in communication with the compressor  15  or other source of the cooling flow  150 . 
         [0019]    The impingement plate  130  of the impingement plenum  110  may have a substantially flat or linear surface  170 . The impingement plate  130  also may have a number of impingement holes  180  therein. The size, shape, configuration and location of the impingement holes  180  may vary as will be described in more detail below. Other components and other configurations may be used herein. 
         [0020]    The impingement cooling system  100  may be used with any type of turbine component or any component requiring cooling. In this example, the impingement cooling system  100  may be used with an undulating or a contoured surface  200 . The contoured surface  200  may have any desired shape or configuration. In this example, the contoured surface  200  may include a number of contoured areas of varying distances from the impingement cooling system  100 . 
         [0021]    In order to maintain a constant heat transfer coefficient across the contoured surface  200 , the spacing of the holes  180  in the impingement plate  130  of the impingement plenum  110  may be adjusted to compensate for the undulation in the contoured surface  200  in a discretized manner. The contoured surface  200  may be divided into a grid  290  with a number of contoured areas  300  therein. Each of the contoured areas  300  may be projected onto an associated projected area  305  on the impingement plate  130 . Each of the projected areas  305  of the impingement plate  130  may have a number of the impingement holes  180  therein of differing size, shape, and configuration based upon the offset of the opposed areas  300  from the projected areas  305 . The group of impingement holes  180  in each of the projected areas  305  thus may have a size  310  and a spacing  320 , both of which may be adjusted uniformly over that local projected area  305  to maintain an average heat transfer coefficient over that discretized area  300  within the contoured surface  200 . The impingement holes  180  thus each may have the variable size  310  and the variable spacing  320  or a sub-set thereof, with both the size  310  and the spacing  320  being held constant over a given projected area  305 . For example, a first area  330  may have a number of closely spaced small holes  180  while a second area  340  may have a number of widely spaced large holes  180 . Any number of sizes and positions may be used herein in any number of the projected areas  305  depending upon the distance to the opposed surface. 
         [0022]    The impingement cooling system  100  thus uses the impingement plenum  110  to provide adequate cooling with a simplified impingement plate design so as to lower costs and increase production. Specifically, the impingement holes  180  may vary with respect to a ratio of the hole diameter to the thickness of the impingement plate  130 , the ratio of the channel height to hole diameter, and the orthogonal spacing of the hole array. Effectiveness may be considered in the context of z/d requirements where d is the hole diameters and z is the average distance from a projected area  305  to a contoured area  300  and/or x/d where x is measured along the length of the impingement plate  130 . Within each projected area  305  of the grid  290 , the size of impingement holes  180  may be adjusted to maintain relative z/d requirements. Within the same area  305 , hole positioning or x/d also may be adjusted to maintain effectiveness. As such, the impingement plate  130  of the impingement plenum  110  may maintain consistent heat transfer coefficients with the use of the linear surface  170  as opposed to a contoured surface. 
         [0023]    It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.