Patent Publication Number: US-8992179-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 turbine of a turbomachine having a multiple hump endwall. 
     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. 
     At one or more axial stages of the turbine, rotating blades typically exhibit strong secondary flows at various turbine stages whereby the high temperature fluids flow in a direction transverse to the main flow direction through the pathway. These secondary flows can negatively impact the stage efficiency at each of those various stages. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the invention, a turbine of a turbomachine is provided and includes first and second endwalls disposed to define a pathway, each of the first and second endwalls including a surface facing the pathway and first and second blades extendible across the pathway from at least one of the first and second endwalls, each of the first and second blades having an airfoil shape and being disposed such that a pressure side of the first blade faces a suction side of the second blade. A portion of the surface of at least one of the first and second endwalls between the first and second blades has at least a first hump proximate to a leading edge and the pressure side of the first blade, and a second hump disposed at 10-60% of a chord length of the first blade and proximate to the pressure side thereof. 
     According to another aspect of the invention, a turbine of a turbomachine is provided and includes first and second annular endwalls disposed to define an annular pathway, each of the first and second endwalls including a surface facing the annular pathway and an annular array of blades extendible across the pathway from at least one of the first and second endwalls, each of the blades having an airfoil shape and being disposed such that a pressure side of one of the blades faces a suction side of an adjacent one of the blades. A portion of the surface of at least one of the first and second endwalls between the one of the blades and the adjacent one of the blades has at least a first hump proximate to a leading edge and the pressure side of the one of the blades, and a second hump disposed at 10-60% of a chord length of the one of the blades and proximate to the pressure side thereof. 
     According to yet another aspect of the invention, a turbomachine is provided and includes a compressor to compress inlet gas to produce compressed inlet gas, a combustor to combust the compressed inlet gas along with fuel to produce a fluid flow and a turbine fluidly coupled to the combustor. The turbine includes first and second endwalls defining an annular pathway through which the fluid flow is directable, the first endwalls being disposed within the second endwall and an axial stage of aerodynamic elements disposed to extend through the pathway between the first and second endwalls and to thereby aerodynamically interact with the fluid flow. The first endwall exhibits non-axisymetric contouring between adjacent aerodynamic elements with multiple humps proximate to a pressure side of one of the aerodynamic elements. 
     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 side view of a portion of a turbine of the gas turbine engine of  FIG. 1 ; and 
         FIG. 3  is a radial view of a topographical map of the portion of the turbine of  FIG. 3 . 
     
    
    
     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 and 2  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 high temperature fluids may be 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  includes a respective hot gas path facing surface  21  and  31  that faces inwardly toward the annular pathway  40 . 
     At one or more axial stages of the turbine  14  an annular array of aerodynamic elements, such as axially aligned blades  50 , are provided. Each blade  50  of each stage 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 high temperature fluids flowing through the pathway  40 . Each of the blades  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  extending between the leading edge  511  and the trailing edge  512  and a suction side  514  opposing the pressure side  513  and extending between the leading edge  511  and the trailing edge  512 . Each of the blades  50  may be disposed at the one or more axial stages such that a pressure side  513  of any one of the blades  50  faces a suction side  514  of an adjacent one of the blades  50  and defines an associated pitch. With this configuration, as the high temperature fluids pass along the pathway  40 , the high temperature fluids aerodynamically interact with the blades  50  and cause the annular array of blades  50  at each axial stage to rotate about a centerline of the turbine  14 . 
     Normally, the configuration of the blades  50  has a tendency to generate secondary flows in directions transverse to the direction of the main flow through the pathway  40 . These secondary flows may originate at or near the leading edge  511  where the incoming endwall boundary layer rolls into two vortices that propagate into the bucket passage and may cause a loss of aerodynamic efficiency. In accordance with aspects, however, the strength of these vortices can be decreased and possibly prevented by placing at least one or more of a first endwall hump near the leading edge  511 . 
     Furthermore, a cross-passage pressure gradient formed between adjacent blades  50  may give rise to another type of secondary flow component as fluid migrates from high to low pressure regions across the passage  40 . This cross-passage flow migration may also cause a loss in aerodynamic performance. In accordance with further aspects, a second endwall hump aft or downstream of the leading edge  511  and the first endwall hump may accelerate the local fluid. Such acceleration may lead to a reduction in cross-passage flow migration to thereby improve aerodynamic efficiencies. 
     Thus, as shown in  FIG. 2  and with reference to  FIG. 3 , a portion  211  of the surface  21  of the first endwall  20  between one of the blades  501  at a particular axial stage of the turbine  14  and an adjacent one of the blades  502  has at least a first hump  60  and a second hump  70  provided thereon. For purposes of clarity and brevity, the first hump  60  and the second hump  70  will be described below as being formed on the first endwall  20 , which may be disposed radially within the second endwall  30 , although it is to be understood that this embodiment is merely exemplary and that similar humps could be provided on the second endwall  30  as well. 
     The first hump  60  may be disposed proximate to the leading edge  511  and the pressure side  513  of one of the blades  501 . The second hump  70  may be disposed at 10-60% of a chord length of one of the blades  501  and proximate to the pressure side thereof  513 . 
     With reference to  FIG. 3 , a topographical map of the first hump  60  and the second hump  70  is illustrated. As shown in  FIG. 3 , the first hump  60  and the second hump  70  are defined at a given axial stage of a turbine  14  between the pressure side  513  of one of the blades (the “first” blade)  501  and the suction side  514  of the adjacent one of the blades (the “second” blade)  502 . The first hump  60  and the second hump  70  rise radially outwardly from the portion  211  of the hot gas path facing surface  21  of the first endwall  20 . The topographical map illustrates that the hot gas path facing surface  21  establishes a zeroed first radial height  80 . The first hump  60  and the second hump  70  each rise radially outwardly from this first radial height  80  through at least second through seventh radial heights  81 - 86  such that they each protrude radially outwardly into the pathway  40 . 
     In accordance with embodiments, the non-dimensional hump radius at the second radial height  81  is approximately 0.175 relative to the first radial height  80 , the non-dimensional hump radius at the third radial height  82  is approximately 0.25 relative to the first radial height  80 , the non-dimensional hump radius at the third radial height  83  is approximately 0.325 relative to the first radial height  80 , the non-dimensional hump radius at the fourth radial height  84  is approximately 0.4 relative to the first radial height  80 , the non-dimensional hump radius at the fifth radial height  85  is approximately 0.475 relative to the first radial height  80  and the non-dimensional hump radius at the sixth radial height  86  is approximately 0.55 relative to the first radial height  80 . 
     In accordance with further embodiments, the first hump  60  may have a height from the hot gas path facing surface  21  of about 6.7% of a span of the first blade  501 , the first hump  60  may be disposed at 0-10% of the chord length of the first blade  501  and the first hump  60  may be disposed at 0-10% of an associated pitch. The second hump  70  may have a height from the hot gas path facing surface  21  of about 5.9% of a span of the first blade  501 , the second hump  70  may be disposed at about 42% of the chord length of the first blade  501  and the second hump  70  may be disposed at about 16.6% of an associated pitch. 
     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.