Patent Publication Number: US-8967959-B2

Title: Turbine of a turbomachine

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to a turbomachine and, more particularly, to a turbomachine having a throat distribution exhibiting endwall throat decambering and pitchline throat overcambering. 
     A turbomachine, such as a gas turbine engine, may include a compressor, a combustor and a turbine. The compressor compresses inlet gas and the combustor combusts the compressed inlet gas along with fuel to produce high temperature fluids. Those high temperature fluids are directed to the turbine where the energy of the high temperature fluids is converted into mechanical energy that can be used to generate power and/or electricity. The turbine is formed to define an annular pathway through which the high temperature fluids pass. 
     First stages of the turbine typically experience strong secondary flows in directions that are transverse to a main flow direction through the pathway. These secondary flows can negatively impact stage efficiencies. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the invention, a turbine of a turbomachine is provided and includes opposing endwalls defining a pathway into which a fluid flow is receivable to flow through the pathway; and a nozzle stage at which adjacent nozzles extend across the pathway between the opposing endwalls to aerodynamically interact with the fluid flow. The adjacent nozzles are configured to define a throat distribution exhibiting endwall throat decambering and pitchline throat overcambering. 
     According to another aspect of the invention, a turbomachine is provided and includes a compressor configured to compress inlet gas to produce compressed inlet gas, a combustor fluidly coupled to the compressor and configured to combust the compressed inlet gas along with fuel to produce a fluid flow and a turbine defining a pathway and being fluidly coupled to the combustor such that the fluid flow is receivable by the turbine to flow through the pathway. The turbine includes opposing endwalls and a nozzle stage at which adjacent nozzles extend across the pathway between the opposing endwalls to aerodynamically interact with the fluid flow and to define a throat distribution exhibiting endwall throat decambering and pitchline throat overcambering. 
     According to yet another aspect of the invention, a turbomachine is provided and includes a compressor configured to compress inlet gas to produce compressed inlet gas, a combustor fluidly coupled to the compressor and configured to combust the compressed inlet gas along with fuel to produce a fluid flow and a turbine defining a pathway and being fluidly coupled to the combustor such that the fluid flow is receivable by the turbine to flow through the pathway. The turbine includes opposing annular endwalls and a nozzle stage at which an annular array of nozzles extend across the pathway between the opposing endwalls to aerodynamically interact with the fluid flow such that any two adjacent nozzles of the annular array define a throat distribution exhibiting endwall throat decambering proximate to the endwalls and pitchline throat overcambering remote from the endwalls. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a schematic diagram of a gas turbine engine; 
         FIG. 2  is a perspective view of a nozzle of a first stage of a turbine of the gas turbine engine of  FIG. 1 ; 
         FIG. 3  is a perspective view of adjacent first stage nozzles at the first stage; 
         FIG. 4  is a schematic radial view of adjacent first stage nozzles at the first stage; and 
         FIG. 5  is a graphical display of a non-dimensional throat distribution defined by the adjacent first stage nozzles. 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIGS. 1-4  and, in accordance with aspects of the invention, a turbomachine  10  is provided as, for example, a gas turbine engine  11 . As such, the turbomachine  10  may include a compressor  12 , a combustor  13  and a turbine  14 . The compressor  12  compresses inlet gas and the combustor  13  combusts the compressed inlet gas along with fuel to produce a fluid flow of, for example, high temperature fluids. Those exemplary high temperature fluids are directed to the turbine  14  where the energy of the high temperature fluids is converted into mechanical energy that can be used to generate power and/or electricity. 
     The turbine  14  includes a first annular endwall  20  and a second annular endwall  30 , which is disposed about the first annular endwall  20  to define an annular pathway  40 . The annular pathway  40  extends from an upstream section  41 , which is proximate to the combustor  13 , to a downstream section  42 , which is remote from the combustor  13 . The high temperature fluids are output from the combustor  13  and pass through the turbine  14  along the pathway  40  from the upstream section  41  to the downstream section  42 . Each of the first and second endwalls  20  and  30  respectively includes a hot gas path facing surface  21  and  31  that facing inwardly toward the annular pathway  40 . 
     The turbine  14  includes one or more axial stages  140  in which respective annular arrays of axially aligned nozzles and blades are provided. These axial stages  140  include a first axial stage  141  that is disposed at a forward portion of the turbine  14 , downstream from an aft portion of the combustor  13  and upstream from subsequent axial stages  142 . 
     The first axial stage  141  includes an annular array of first stage nozzles  50 , which are provided such that each nozzle  50  is extendible across the pathway  40  from at least one or both of the first and second endwalls  20  and  30  to aerodynamically interact with the flow of the high temperature fluids. Each of the nozzles  50  may have an airfoil shape  51  with a leading edge  511  and a trailing edge  512  that opposes the leading edge  511 , a pressure side  513  and a suction side  514 . The pressure side  513  extends between the leading edge  511  and the trailing edge  512 . The suction side  514  opposes the pressure side  513  and also extends between the leading edge  511  and the trailing edge  512 . Each of the nozzles  50  at the first axial stage  141  may be disposed such that a pressure side  513  of any one of the nozzles  50  faces a suction side  514  of an adjacent one of the nozzles  50 . With this configuration, as the high temperature fluids flow toward the pathway  40 , the high temperature fluids aerodynamically interact with the nozzles  50  and are forced to flow with an angular momentum relative to a centerline of the turbine  14 . 
     Normally, first turbine stages, such as the first axial stage  141 , experience strong secondary flows in a direction transverse to a main flow direction through the pathway  40 . These secondary flows can negatively impact stage efficiencies. In accordance with aspects, however, radial vortexing and stack distribution for the reduction of secondary flows is provided for the nozzles  50  of at least the first axial stage  141 . As shown in  FIGS. 3 and 4 , any two adjacent nozzles  50  of the first axial stage  141  define a throat distribution  60  measured at a narrowest region of the pathway  40  between the adjacent nozzles  50  that exhibits endwall throat decambering radially proximate to the first and second endwalls  20  and  30  and pitchline throat overcambering radially remote from the first and second endwalls  20  and  30 . That is, the nozzles  50  of at least the first axial stage  141  define a throat distribution  60  that exhibits endwall throat decambering at radial regions near the first and second endwalls  20  and  30 . By contrast, the nozzles  50  of at least the first axial stage  141  define a throat distribution  60  that exhibits endwall throat overcambering at a radial region provided substantially centrally (i.e., along the pitchline) between the first and second endwalls  20  and  30   
     With reference to  FIG. 5 , a non-dimensional expression of the throat distribution  60  is approximately:
 
 y=− 3 −07   x   3 +0.0001 x   2 −0.0067 x +1.0299,
 
     where y is the non-dimensional throat distribution and x is a span location between the opposing first and second endwalls  20  and  30  with 0% span representing the first endwall  20  and 100% span representing the second endwall  30 . This equation and substantially similar equations can be solved for y to determine the non-dimensional throat distribution defined by the adjacent nozzles  50  at any span location (i.e., the 0% span location, the 20% span location, etc.). 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.