Abstract:
A turbine vane usable in a turbine engine and having at least one cooling system. The cooling system including an aft cooling circuit formed from at least one serpentine cooling path. The serpentine cooling path having at least one rib may include bypass orifices for allowing air to pass through the rib to shorten the distance of the serpentine cooling path through which at least some of the air passes. The bypass orifices allow a greater quantity of air to pass through the vane and be expelled into a disc to which the vane is movably coupled as compared to a similar shaped and sized serpentine cooling path not having the bypass orifices.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention is directed generally to turbine vanes, and more particularly to hollow turbine vanes having cooling channels for passing fluids, such as air, to cool the vanes and supply air to the disc of a turbine assembly.  
       BACKGROUND  
       [0002]     Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine vane and blade assemblies to these high temperatures. As a result, turbine vanes and blades must be made of materials capable of withstanding such high temperatures. In addition, turbine vanes and blades often contain cooling systems for prolonging the life of the vanes and blades and reducing the likelihood of failure as a result of excessive temperatures.  
         [0003]     Typically, turbine vanes are formed from an elongated portion forming a vane having one end configured to be coupled to a vane carrier and an opposite end configured to be movably coupled to a rotatable disc. The vane is ordinarily composed of a leading edge, a trailing edge, a suction side, and a pressure side. The inner aspects of most turbine vanes typically contain an intricate maze of cooling circuits forming a cooling system. The cooling circuits in the vanes receive air from the compressor of the turbine engine and pass the air through the ends of the vane adapted to be coupled to the vane carrier. The cooling circuits often include multiple flow paths that are designed to maintain all aspects of the turbine vane at a relatively uniform temperature. At least some of the air passing through these cooling circuits is exhausted through orifices in the leading edge, trialing edge, suction side, and pressure side of the vane. A substantially portion of the air is passed into a disc to which the vane is movable coupled. The air supplied to the disc may be used, among other uses, to cool turbine blade assemblies coupled to the disc.  
         [0004]     As turbine engines have been made more efficient, increased demands have been placed on the cooling systems of turbine vanes and blades. Cooling systems have been required to supply more and more cooling air to various systems of a turbine engine to maintain the structural integrity of the engine and to prolong the turbine&#39;s life by removing excess heat. However, some cooling systems lack the capacity to deliver an adequate flow rate of cooling air to a turbine engine. In particular, turbine vanes often lack the ability to permit a sufficient amount of cooling air to flow through the vane and into the disc. Thus, a need exists for a turbine vane having a cooling system capable of dissipating heat from the vane and capable of passing a sufficient amount of cooling air through the vane and into the disc.  
       SUMMARY OF THE INVENTION  
       [0005]     This invention relates to a turbine vane having a cooling system including at least a forward cooling circuit and an aft cooling circuit for allowing an increased amount of cooling fluid, such as, but not limited to, air, to pass through the vane to a disc while cooling the vane to a temperature within an acceptable range. The turbine vane may be formed from a generally elongated vane formed from at least one outer wall and having a leading edge, a trailing edge, a pressure side, and a suction side. In at least one embodiment, the aft cooling circuit may be formed from a serpentine cooling path. The serpentine cooling path may be formed, in part, from a first inflow section, a first outflow section, and a second inflow section. The first inflow section may extend from an opening at a first end of the turbine vane adapted to be coupled to a vane carrier and a first end at 100 percent span of the serpentine cooling path to a first turn at 0 percent span of the serpentine cooling path. In at least one embodiment, the first inflow section may be generally parallel with a longitudinal axis of the turbine vane.  
         [0006]     The first outflow section may be in communication with the first inflow section and may extend from the first turn generally toward the first end of the serpentine cooling path where it is coupled to the second turn. The second inflow section may be in communication with the first outflow section through the second turn and may extend from the second turn to an opening in a second end of the turbine vane adapted to be movably coupled to a disc.  
         [0007]     In at least one embodiment, the first inflow section and the first outflow section may be separated by at least one rib extending from the first end of the serpentine cooling path substantially to the second end of the serpentine cooling path. The at least one rib may include one or more bypass orifices creating a pathway between the first inflow section and the first outflow section. The bypass orifices may be positioned between about 15 percent span of the serpentine cooling path and about 85 percent span of the serpentine cooling path. The diameter of the bypass orifices may be equal or different sizes. In at least one embodiment, the diameter of the bypass orifices may be about 4 millimeters (mm).  
         [0008]     In order to improve the fluid dynamics of the air flowing through the aft cooling circuit, the cross-sectional area of the first inflow section may be different at different locations in the aft cooling circuit. In particular, the cross-sectional area of the first inflow section may decrease moving from the 100 percent span of the serpentine cooling path toward the 0 percent span of the serpentine cooling path. Specifically, a cross-sectional area at the 100 percent span of the serpentine cooling path may be larger than a cross-sectional area at the 10 percent span of the serpentine cooling path. Further, the cross-sectional area at the 100 percent span of the serpentine cooling path may be larger than a cross-sectional area at the 50 percent span of the serpentine cooling path. For instance, the cross-sectional area of the first inflow section at the 50 percent span of the serpentine cooling path may be about 0.7 units, whereas a cross-sectional area at the 100 percent span of the serpentine cooling path may be about 1 unit. In addition, the cross-sectional area at the 50 percent span of the serpentine cooling path may be larger than a cross-sectional area at the 10 percent span of the serpentine cooling path. In at least one embodiment, the cross-sectional area of the first inflow section at 10 percent span of the serpentine cooling path may be about 0.4 units, whereas a cross-sectional area at the 100 percent span of the serpentine cooling path may be about 1 unit.  
         [0009]     In operation, a cooling fluid, such as, but not limited to air, may pass through one or more orifices at 100 percent span of the vane into the forward and aft cooling circuits. At least some of the cooling fluid entering the forward cooling circuit flows through the vane and into a disc, and at least some of the cooling fluid flows exits the vane through a plurality of exhaust orifices in the leading edge and the suction and pressure sides of the vane. The air entering the aft cooling circuit flows through a serpentine cooling path and is exhausted into the disc or through a plurality of orifices in a trailing edge or in the suction or pressure sides of the vane. As the air flows through a first inflow section of the serpentine cooling path, air may pass through one or more bypass orifices in a rib separating the first inflow section and the first outflow section. By allowing air to pass through the rib, rather than having air flow through the entire length of the first inflow section, through the first turn, and through the entire length of the first outflow section, the amount of air capable of flowing through the serpentine cooling path is increased. The increased air flow through the serpentine cooling path and into the disc is advantageous in at least some turbine engines requiring greater amounts of cooling fluid. These and other embodiments are described in more detail below. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate embodiments of the presently disclosed invention and, together with the description, disclose the principles of the invention.  
         [0011]      FIG. 1  is a perspective view of a turbine vane having features according to the instant invention.  
         [0012]      FIG. 2  is cross-sectional view of the turbine vane shown in  FIG. 1  taken along line  2 - 2 .  
         [0013]      FIG. 3  is a cross-sectional view of the turbine blade shown in  FIGS. 1 and 2  taken along line  3 - 3  at 10 percent span of the serpentine cooling path.  
         [0014]      FIG. 4  is a cross-sectional view of the turbine blade shown in  FIGS. 1 and 2  taken along line  4 - 4  at 50 percent span of the serpentine cooling path.  
         [0015]      FIG. 5  is a cross-sectional view of the turbine blade shown in  FIGS. 1 and 2  taken along line  5 - 5  at 100 percent span of the serpentine cooling path. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     As shown in  FIGS. 1-5 , this invention is directed to a turbine vane  10  having a cooling system  12  in inner aspects of the turbine vane  10  for use in turbine engines. In particular, the cooling system  10  includes a forward cooling circuit  14  and an aft cooling circuit  16 , as shown in  FIGS. 1 and 2 , for passing cooling fluids, which may be, but is not limit to, air, through the turbine vane  10 . The aft cooling circuit  16  may have one or more bypass orifices  17  for short circuiting the aft cooling circuit  16 , thereby allowing a greater amount of cooling air to flow through the aft cooling circuit  16 .  
         [0017]     As shown in  FIG. 1 , the turbine vane  10  may be formed from a generally elongated vane  18  having an outer surface  20  adapted for use, for example, in a first stage of an axial flow turbine engine. Outer surface  20  may be formed from a housing  22  having a generally concave shaped portion forming pressure side  24  and may have a generally convex shaped portion forming suction side  26 . The outer surface  20  may have one or more exhaust orifices  28  coupled to the cooling system  10  inside the turbine vane  10 . The exhaust orifices  28  may be positioned in the leading edge  30 , the trailing edge  32 , or in other positions.  
         [0018]     As shown in  FIG. 2 , the forward cooling circuit  14  may have any one of a multitude of configurations. The cooling system  12  is not restricted to a particular configuration of the forward cooling circuit  14 . Rather, the forward cooling circuit  14  may be any configuration capable of adequately cooling the forward aspects of the vane  18  and passing air through the vane from an OD at a 100 percent span  34  of the elongated vane  18  to an ID at 0 percent span  36  of the elongated vane  18 . A cross-sectional area of the forward cooling circuit  14  at about 100 percent span  34  of the elongated vane  18  may be greater than a cross-sectional area of the forward cooling circuit  14  at about 0 percent span  36  of the elongated vane  18 . The 100 percent span  34  of the elongated vane  18  is located at a first end  38  of the vane  18 . In at least one embodiment, the first end  38  may be configured to be coupled to a vane carrier (not shown) in a turbine engine. The 0 percent span  36  of the elongated vane  18  is located at a second end  40  of the vane  18 . In at least one embodiment, the second end  40  may be configured to be movable coupled to a disc (not shown). The vane  18  may be coupled to the vane carrier so that the vane  18  is held relatively motionless, except for at least vibrations and material expansion and contraction, relative to the rotating disc. The vane  18  may include seals (not shown) at the second end  40  for sealing the vane  18  to the disc.  
         [0019]     In at least one embodiment, the aft cooling circuit  16  may include a serpentine cooling path  42 , as shown in  FIG. 2 . The aft cooling circuit  16  may also include one or more cooling cavities for receiving air, directly or indirectly, from an orifice  44  in the first end  38  of the vane  18  and passing the air through the vane  18  to a disc. The aft cooling circuit  16  may also include one or more exhaust orifices  28  in the trailing edge  32  of the vane  18 . The serpentine cooling path  42  may include, in part, a first inflow section  50 , a first outflow section  52 , and a second inflow section  54 . The first inflow section  50  may be coupled to the inlet orifice  44  at a first end  38  of the vane  18 , which is also the first end  48  of the serpentine cooling path  42  at 100 percent span  56  of the serpentine cooling path  42 . The first inflow section  50  may extend toward a first turn  58  at 0 percent span  60  of the serpentine cooling path  42 . In at least one embodiment, the first inflow section  50  may be, but is not limited to being, substantially parallel with a longitudinal axis  62  of the vane  18 .  
         [0020]     The 100 percent span  56  of the serpentine cooling path  42  may be located at 100 percent span  34  of the elongated vane  18 . However, the 100 percent span  56  of the serpentine cooling path  42  may be located at other positioning relative to the elongated vane  18 . Likewise, while the 0 percent span  60  of the serpentine cooling path  42  may be located at the 0 percent span  36  of the elongated vane  18 , as shown in  FIG. 2 , the 0 percent span  60  of the serpentine cooling path  42  may be located at other positions relative to the elongated vane  18 . For instance, the 0 percent span of the serpentine cooling path  42  may be located between about 0 percent span  36  of the elongated vane  18  and about 80 to 90 percent span of the elongated vane  18 .  
         [0021]     The first outflow section  52  may be in communication with the first inflow section  50  and be coupled to the first turn  58 . The first outflow section  52  may extend toward the first end  48  of the serpentine cooling path  42 . The first outflow section  52  may or may not extend to the 100 percent span point  56  of the serpentine cooling path  42 . In at least one embodiment, the first outflow section  52  may be generally parallel with the first inflow section  50 , and in some embodiments, may be generally parallel with the longitudinal axis  62  of the vane  18 . The first outflow section  52  may be coupled to a second turn  64 . The second inflow section  54  may be coupled to the second turn  64  and may extend toward an exhaust orifice  66  in the vane  18  for exhausting cooling fluids into a disc. The exhaust orifice  66  or surrounding housing may be configured to be movably coupled to a disc (not shown) that is capable of rotating while the vane  18  remains relatively stationary. The second inflow section  54  may include one or more exhaust orifices  28  in the trailing edge  32  of the blade. In other embodiments, the second inflow section  54  may be coupled to one or more exhaust orifices  66  in the vane  18 . In at least one embodiment, as shown in  FIG. 2 , at least a portion of the serpentine cooling path  42  may extend from the 100 percent span  34  of the elongated vane  18  to the 0 percent span  36  of the elongated vane  18 .  
         [0022]     In at least one embodiment, the first inflow section  50  and the first outflow section  52  are separated by one or more ribs  68 . The rib  68  may extend from the 100 percent span  56  of the serpentine cooling path  42  to between about 2 percent span and about 20 percent span of the serpentine cooling path  42 . The rib  68  may include one or more bypass orifices  17  extending between the first inflow section  50  and the first outflow section  52 . The bypass orifices  17  may be positioned between about 15 percent span  70  of the serpentine cooling path  42  and about 85 percent span  72  of the serpentine cooling path  42 . The bypass orifices  17  may be positioned equidistant from each other, positioned in a pattern, or haphazardly positioned on the rib  68 , or any combination thereof. The bypass orifices  17  may have different diameters varying between about 2 mm and about 10 mm, or may all have equal diameters.  
         [0023]     In at least one embodiment, the fluid dynamics of the cooling system  12  may be improved by adjusting the cross-sectional area of at least the first inflow section  50 . In particular, the cross-sectional area of the first inflow section  50  may decrease moving from the 100 percent span  56  of the serpentine cooling path  42  to the 0 percent span  60  of the serpentine cooling path  42 . Specifically, a cross-sectional area at the 100 percent span  56  of the serpentine cooling path  42 , as shown in  FIG. 5 , may be larger than a cross-sectional area at the 10 percent span  76  of the serpentine cooling path  42 , as shown in  FIG. 3 . Further, the cross-sectional area at the 100 percent span  56  of the serpentine cooling path  42  may be larger than a cross-sectional area at the 50 percent span  74  of the serpentine cooling path  42  as shown in  FIG. 4 . For instance, the cross-sectional area of the first inflow section  50  at the 50 percent span  74  of the serpentine cooling path  42  may be about 0.7 units, whereas a cross-sectional area at the 100 percent span  74  of the serpentine cooling path  42  may be about 1 unit. In addition, the cross-sectional area at the 50 percent span  74  of the serpentine cooling path  42 , as shown in  FIG. 4 , may be larger than a cross-sectional area at the 10 percent span  76  of the serpentine cooling path  42 , as shown in  FIG. 3 . In at least one embodiment, the cross-sectional area of the first inflow section  50  at 10 percent span  76  of the serpentine cooling path  42  may be about 0.4 units, whereas a cross-sectional area at the 100 percent span  74  of the serpentine cooling path  42  may be about 1 unit.  
         [0024]     In operation, a cooling fluid, which may be, but is not limited to, air, may enter the vane  18  through the inlet orifice  44  and enter the cooling system  12 , as shown in  FIGS. 1 and 2 . The air not only removes heat from the vane  18  during operation of a turbine engine in which the vane  18  is located, but also supplies air to inner aspects of a disc (not shown). The air supplied to the disc is used, at least in part, to cool turbine blades of the turbine engine. The air entering the inlet orifice  44  passes into the forward and aft cooling circuits  14  and  16 . At least some of the air passing into the forward cooling circuit  14  passes through the vane to the disc, and the remainder of the air passes through one or more exhausts orifices  28  in the leading edge  30  of the vane  18 . Air passing into the aft cooling circuit  16  enters the first inflow section  50  of the serpentine cooling path  42 . At least a portion of the air travels along the length of the first inflow section  50  to the first turn  58 , while a portion of the air passes through the bypass orifices  17  in the rib  68 . By allowing a portion of the air to pass through the bypass orifice  17  in the rib  68 , rather than flowing through the entire length of the first inflow section  50 , a larger flow rate of air through the aft cooling circuit  16  is achieved. The increased flow rate results in a greater amount of air being delivered to the disc, which is beneficial for at least some turbine engines. The increased flow may be used for interstage cooling, supplying air to the turbine blade assemblies, and for accounting for leakages between static components and moving components in the turbine engine. In addition, the pressure drop between the inlet orifice  78  and the exhaust orifice  46  is less than serpentine cooling paths not having bypass orifices.  
         [0025]     The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of this invention.