Patent Publication Number: US-7217081-B2

Title: Cooling system for a seal for turbine vane shrouds

Description:
FIELD OF THE INVENTION 
     This invention is directed generally to turbine vanes and, more particularly, to turbine vane shroud assemblies. 
     BACKGROUND 
     Typically, gas turbine engines operate at high temperatures that may exceed 2,500 degrees Fahrenheit. During operation, turbine engines expose turbine vanes, turbine vane shrouds, and other components to these high temperatures. As a result, turbine vanes and shrouds must be made of materials capable of withstanding such high temperatures. Turbine vanes often contain cooling systems for prolonging the life of the vanes and reducing the likelihood of failure as a result of excessive temperatures. However, these cooling systems often do not include cooling channels for reducing the temperature of seals positioned in seal grooves between adjacent turbine vanes in turbine shrouds. Without adequate cooling, these seals are susceptible to premature failure. Thus, a need exists for a cooling system for seals in seal grooves of turbine vane shrouds to reduce the likelihood of premature failure. 
     SUMMARY OF THE INVENTION 
     This invention relates to a seal for sealing gaps between adjacent turbine vane shrouds in a turbine engine. The seal may include a cooling system for removing heat from a turbine vane, a turbine vane shroud, and a seal to prevent premature failure. The seal may, in at least one embodiment, be formed from an elongated body configured to fit within seal grooves on side surfaces of turbine vane shrouds. The seal grooves may be configured such that a seal groove on a first turbine vane shroud is configured to receive about half of a seal, and a recess in a second turbine vane shroud positioned proximate to the first turbine vane shroud is configured to receive the remainder of the seal. In at least one embodiment, the seal may be formed from a first end and a second end generally opposite the first end, a top surface and a bottom surface generally opposite the top surface, and a first side surface and a second side surface generally opposite the first side surface. 
     The cooling channel may extend generally parallel to a longitudinal axis of the elongated body on an outer surface of the elongated body. In at least one embodiment, the cooling channel may extend generally from a midpoint between the first and second ends to the first end. The cooling channel, in at least one embodiment, may contact a first side surface and a top surface of the elongated body forming a generally rectangular cooling channel. The cooling channel may be formed on two sides by the seal and on two sides by the turbine vane shroud. The cooling channel may extend to the first end of the elongated body where it may contact an exhaust channel. The exhaust channel may, in at least one embodiment, extend the width of the elongated body and provide a flow path for cooling fluids to be exhausted from the cooling system. 
     During operation of a turbine engine, hot combustion gases pass turbine vanes and turbine vane shrouds, which cause these components to increase in temperature. Cooling fluids may be passed through the cooling system in the seal to remove heat from the turbine vane, the turbine vane shroud, and the seal to prevent premature failure of the components. The cooling fluids may be passed through a cooling fluid supply port in the shroud and into a cooling fluid supply orifice in the seal. The cooling fluids may flow through the cooling channel and remove heat from walls of the cooling channel. The cooling fluids may collect in the exhaust channel and be exhausted from the cooling system through a gap between adjacent turbine vane shrouds. 
     Also disclosed is a method of removing heat from a turbine vane shroud, comprising passing a cooling fluid through an orifice in the turbine vane shroud; passing the cooling fluid into a cooling channel of a cooling system in a seal in the turbine vane shroud such that the cooling fluid flows from midchord to a leading edge of the turbine vane shroud along a longitudinal axis of the seal, whereby the seal comprises an elongated body having an exterior shape capable of fitting inside a seal groove on the shroud of the turbine vane; a cooling channel on the elongated body extending on an outer surface of the elongated body generally parallel to the longitudinal axis of the elongated body; a cooling fluid supply orifice in communication with the cooling channel; and wherein the cooling channel extends generally from a first side surface about halfway toward a second side surface of the elongated body and extends from a midpoint of the elongated body to a first end of the elongated body; and exhausting the cooling fluid from the cooling channel through a gap between adjacent turbine vane shrouds. 
     An advantage of this invention is that the cooling fluids remove heat and reduce the temperature of the surrounding components, thereby substantially reducing the risk of premature failure of the components. 
     Another advantage of this invention is that the cooling system improves cooling of the seal groove and reduces hot spot formation in various components of a turbine vane. 
     Yet another advantage of this invention is that as cooling fluids are exhausted from the gap between adjacent shrouds, the cooling fluids my reduce the temperature of the external side of the seal from the leading edge to the trailing edge of the seal. 
     These and other embodiments are described in more detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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. 
         FIG. 1  is a perspective view of turbine vane shrouds including aspects the invention. 
         FIG. 2  is a top plan view of a seal of the invention. 
         FIG. 3  is a cross-sectional detail view of the seal and adjacent turbine vane shrouds shown in  FIG. 2  taken at detail  3 — 3 . 
         FIG. 4  is a cross-sectional detail view of the seal and adjacent turbine vane shrouds shown in  FIG. 2  taken at detail  4 — 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIGS. 1–4 , this invention is directed to a seal  10  for sealing gaps  12  between turbine vane shrouds  14 , which may also be referred to as shroud segments that collectively form a shroud in a turbine engine. The seal  10  includes a cooling system  16  for removing heat from the seal  10  to prevent premature failure of the seal  10 , the turbine vane shroud  14 , and the turbine vane. The cooling system  16  may be configured to receive cooling fluids, which may be, but are not limited to, air, from one or more cooling fluid supply ports  18 , pass the cooling fluids through the cooling system  16 , and exhaust the cooling fluids through a gap  12  between adjacent turbine vane shrouds  14 . 
     As shown in  FIG. 2 , the seal  10  may be formed from an elongated body  22  configured to fit into seal grooves  24  on side surfaces  26  of the turbine vane shrouds  14 . The seal  10 , as shown in  FIGS. 2 and 3 , may have a first end  28  and a second end  30  generally opposite the first end  28 , a top surface  32  and a bottom surface  34  generally opposite the top surface  32 , and a first side surface  36  generally orthogonal to the top surface  32  and a second side surface  38  generally opposite the first side surface  36 . Corners of the elongated body  22  may or may not be filleted or tapered, as shown in  FIGS. 3 and 4 . A cooling channel  20  may be formed on a portion of the top surface  32  and a portion of the first side surface  36 . In at least one embodiment, the cooling channel  20  may form a generally rectangular shape formed by portions of the seal  10  and the turbine vane shroud  14 . The cooling channel  20  may extend generally along, or parallel to, a longitudinal axis  40  of the elongated body  22 . In at least one embodiment, the cooling channel  20  extends substantially from a midpoint of the elongated body  22  to the first end  28 . The cooling channel  20  may extend generally midway into the elongated body between the top surface  32  and the bottom surface  34 . In addition, the cooling channel  20  may extend from a first side surface  36  about half way toward a second side surface  38 . The cooling channel  20  is not limited to the this configuration but may include other appropriate configurations capable of channeling cooling fluids through the turbine vane shroud  14  to reduce the temperature of the shroud  14  and the seal  10 . In other embodiments, the cooling channel  20  may have other lengths, widths, or depths. 
     The seal  10  may also include a cooling fluid supply orifice  42  for supplying cooling fluids to the cooling channel  20 . The cooling fluid supply orifice  42  may extend generally orthogonal to the bottom surface  34  and terminate at the top surface  32  of the cooling channel  20 . In other embodiments, the cooling fluid supply orifice  42  may have other configurations. The cooling fluid supply orifice  42  may be aligned with the cooling fluid supply port  18  such that cooling fluids may flow from the cooling fluid supply port  18  into the cooling fluid supply orifice  42  and then into the cooling channel  20 . The cooling fluid supply orifice  42  may be sized based on the anticipated flow rate of cooling fluids necessary to achieve sufficient heat removal from the shroud  14  and the seal  10 . The cooling fluid supply orifice  42  may be, but is not limited to being, generally circular. The cooling fluid supply orifice  42  may have other appropriate configurations as well. 
     The cooling system  16  may also include an exhaust channel  44  coupled to the cooling channel  20  for exhausting cooling fluids from the cooling system  16 . The exhaust channel  44  may exhaust gases between a gap  12  between adjacent turbine vane shrouds  14 . In at least one embodiment, as shown in  FIG. 4 , the exhaust channel  44  may extend the width of the elongated body  22  forming the seal  10 . The exhaust channel  44  may have a depth substantially equal to a depth of the cooling channel  20 . The exhaust channel  44  may extend into the elongated body  22  a distance sufficient to enable the exhaust channel  44  to collect cooling and exhaust the cooling fluids from the cooling system  16 . In other embodiments, the exhaust channel  44  may have other widths, heights, and depths. 
     During operation of a turbine engine, hot combustion gases flow past turbine vane assemblies and increase the temperature of turbine vanes and turbine vane shrouds  14 . Cooling fluids, such as, but not limited to, air, may be passed through the cooling system  16  to remove heat from the turbine vane shroud  14 , the turbine vane, and the seal  10  to prevent premature failure. Cooling fluids may be injected into the cooling system  16  through a cooling fluid supply port  18 . The cooling fluids may flow from the cooling fluid supply port  18  and into the cooling fluid supply orifice  42 . The cooling fluids flow from the cooling fluids supply orifice  42  into the cooling channel  20  where the cooling fluids contact surfaces of the seal  10  and a turbine vane shroud  14 . In this manner, the cooling fluids flow from midchord of the turbine vane to a leading edge along the seal  10 . The cooling fluids remove heat from the turbine vane shroud  14  by convection and flow from the cooling fluid supply orifice  42  toward the first end  28 . As the cooling fluids flow toward the first end  28 , the cooling fluids increase in temperature. The cooling fluids collect in the exhaust channel  44  at the first end  28  and are exhausted from the cooling system  16  through the gap  12  between adjacent turbine vane shrouds  14 . 
     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.