Gas turbine engines and methods for cooling components thereof with mid-impeller bleed cooling air

Abstract

Gas turbine engines and methods for cooling components thereof with mid-impeller bleed (MIB) cooling air having a pressure are provided. The gas turbine engine has a compressor comprising an impeller body and an impeller shroud at least partially surrounding the impeller body. The impeller shroud has a plurality of MIB openings disposed therein. At least one edge treatment is provided thereto. The edge treatment substantially preserves pressure of the cooling air during entrance into and discharge out of the MIB opening. The plurality of MIB openings may be extended MIB openings in a thickened impeller shroud. The centerline of the MIB openings may be oriented to be substantially aligned with an averaged local absolute flow velocity vector of the cooling air at the inlet section of the MIB opening in order to extract cooling air in a direction that has a vector component in a tangential, an axial, and a radial flow direction.

1 . A method for cooling components of a gas turbine engine with mid-impeller bleed (MIB) cooling air having a pressure, the gas turbine engine having a compressor comprising an impeller body and an impeller shroud at least partially surrounding the impeller body, the method comprising:
 providing at least one edge treatment to at least one MIB opening of a plurality of MIB openings disposed in the impeller shroud, the at least one edge treatment substantially preserving the pressure of the MIB cooling air during entrance into, discharge out of, or both entrance into and discharge out of the at least one MIB opening.   
     
     
         2 . The method of  claim 1 , wherein the step of providing at least one edge treatment comprises providing the at least one edge treatment at one or both of a leading edge and a trailing edge of one or both of an entrance into and an exit out of the at least one MIB opening. 
     
     
         3 . The method of  claim 2 , wherein the step of providing at least one edge treatment comprises providing a radial edge, an angled edge, or a combination thereof 
     
     
         4 . The method of  claim 1 , further comprising the step of forming the impeller shroud prior to or substantially simultaneously with the step of providing at least one edge treatment. 
     
     
         5 . The method of  claim 4 , wherein the step of forming the impeller shroud comprises forming the plurality of MIB openings disposed therein, each MIB opening of the plurality of MIB openings having an inlet section, an outlet section, and a conical diffuser section between the inlet and outlet sections, the entrance into the at least one MIB opening at the inlet section and the exit out of the at least one MIB opening at the outlet section. 
     
     
         6 . The method of  claim 5 , wherein the step of forming the impeller shroud comprises orienting a centerline of each MIB opening of the plurality of MIB openings to be substantially aligned with an averaged local absolute flow velocity vector of the MIB cooling air at the inlet section of each MIB opening. 
     
     
         7 . The method of  claim 6 , wherein the step of forming the impeller shroud comprises orienting the plurality of MIB openings to extend through the impeller shroud at a predetermined tangential angle, a predetermined axial angle, and a predetermined radial angle to extract the MIB cooling air in a direction that has a vector component in a tangential, an axial, and a radial flow direction. 
     
     
         8 . The method of  claim 7 , wherein the step of forming the impeller shroud comprises forming a thickened impeller shroud and wherein the plurality of MIB openings comprise a plurality of extended MIB openings disposed in the thickened impeller shroud each having an extended inlet section, an extended outlet section, and an elongated conical diffuser section between the extended inlet and outlet sections. 
     
     
         9 . The method of  claim 8 , wherein the step of providing at least one edge treatment comprises providing the at least one edge treatment to at least one extended MIB opening of the plurality of extended MIB openings disposed in the thickened impeller shroud. 
     
     
         10 . The method of  claim 9 , wherein the step of providing at least one edge treatment comprises providing the at least one edge treatment at one or both of the leading edge and the trailing edge of one or both of the entrance into the extended inlet section and the exit of the extended outlet section. 
     
     
         11 . The method of  claim 10 , wherein the step of providing at least one edge treatment comprises providing a radial edge, an angled edge, or a combination thereof 
     
     
         12 . A gas turbine engine including a compressor that compresses inlet air into intermediate pressure cooling air and high pressure air, the intermediate pressure cooling air formed upstream of the high pressure air, the compressor comprising
 an impeller;   an impeller shroud; and   a plurality of MIB openings disposed in the impeller shroud and having a length co-terminating with a thickness of the impeller shroud, and each MIB opening of the plurality of MIB openings having an inlet section in flow communication with an engine flow path to extract the intermediate pressure cooling air therefrom, an outlet section in flow communication with a turbine, and a conical diffuser section between the inlet and outlet sections, at least one MIB opening of the plurality of MIB openings having at least one edge treatment.   
     
     
         13 . The gas turbine engine of  claim 12 , wherein the at least one edge treatment is at one or both of a leading edge and a trailing edge of one or both of an entrance into the inlet section and an exit of the outlet section. 
     
     
         14 . The gas turbine engine of  claim 13 , wherein the at least one edge treatment comprises a radial edge, an angled edge, or a combination thereof 
     
     
         15 . The gas turbine engine of  claim 12 , wherein a centerline orientation of each MIB opening of the plurality of MIB openings is substantially aligned with an averaged local absolute flow velocity vector of the intermediate pressure cooling air to extract tangential, axial, and radial velocity flow components therefrom. 
     
     
         16 . The gas turbine engine of  claim 12 , wherein the plurality of MIB openings comprise a plurality of extended MIB openings and the impeller shroud comprises a thickened impeller shroud. 
     
     
         17 . The gas turbine engine of  claim 16 , wherein the inlet section and the outlet section of the plurality of extended MIB openings have an increased area and the conical diffuser section thereof is elongated. 
     
     
         18 . A compressor for a gas turbine engine, the compressor comprising:
 an impeller body having an impeller exit;   a thickened impeller shroud at least partially surrounding the impeller body and having a plurality of extended mid-impeller bleed (MIB) openings extending therethrough adapted to extract at least a portion of a tangential flow component, an axial flow component, and a radial flow component of cooling air from an engine flow path and disposed at a distance from the impeller exit, the plurality of extended MIB openings each having:
 an inlet section, an outlet section, and an elongated conical diffuser section between the inlet and outlet sections, the inlet section having a leading edge and a trailing edge at an entrance thereof and the outlet section having a leading edge and a trailing edge at an exit thereof; 
 a centerline orientation adapted to be substantially aligned with an averaged local absolute flow velocity vector of the cooling air at the inlet section of the extended MIB opening. 
   
     
     
         19 . The compressor of  claim 18 , wherein one or both of the leading and trailing edges at one or both of the entrance and exit of the extended MIB opening is shaped to define at least one edge treatment. 
     
     
         20 . The compressor of  claim 19 , wherein the at least one edge treatment comprises a radial edge, an angled edge, or a combination thereof