Turbine blade tip

Abstract

A tip rail configured to reduce stress when formed from a single crystal alloy is disclosed. The tip rail may be formed from at least one single crystal alloy oriented in a low modulus direction such that a gap exists at a location where the axis of orientation is positioned at a 45 degree angle to the outer surface of the suction side to reduce stress on the tip rail. The tip rail may be separately formed from a generally elongated blade to which the tip rail is configured to be attached. The tip rail may form a leading edge region recess proximate to the leading edge between an inner edge of the tip rail on the suction side and an inner edge of the tip rail on the pressure side and may form a trailing edge region recess proximate to the trailing edge. The gap reduces stress during use operation of a gas turbine engine in which the tip rail is attached to a turbine airfoil.

1 . A turbine blade, comprising:
 a generally elongated blade having a leading edge, a trailing edge, a pressure side extending from the leading edge to the trailing edge, a suction side extending from the leading edge to the trailing edge and opposite to the pressure side, a tip at a first end, and a root coupled to the blade at an end generally opposite the first end for supporting the blade and for coupling the blade to a disc;   a tip rail coupled to the tip at the first end, extending radially outward and configured such that an outer surface of the tip rail is generally aligned with an outer side surface of the turbine blade defining a cross-sectional profile of the turbine blade for a portion of the outer side surface of the turbine blade, wherein a leading edge region recess is formed proximate to the leading edge between an inner edge of the tip rail on the suction side and an inner edge of the tip rail on the pressure side and defined by an outer surface of the tip of the generally elongated blade, and a trailing edge region recess is formed proximate to the trailing edge between an outer surface of the tip rail and a tip edge at an intersection between the outer side surface and the outer surface of the tip such that at least a portion of the tip edge at the pressure side is exposed without the tip rail;   wherein the tip rail is formed from a single crystal orientation; and   wherein the tip rail includes a gap located adjacent to the suction side of the generally elongated blade to limit the formation of stress in the tip rail along the suction side.   
     
     
         2 . The turbine blade of  claim 1 , wherein the tip rail is formed from at least one single crystal alloy oriented such that an axis of orientation is positioned to reduce stress on the tip rail. 
     
     
         3 . The turbine blade of  claim 2 , wherein the tip rail is formed from at least one single crystal alloy oriented in a low modulus direction such that the gap exists at a location in the tip rail where the axis of orientation is positioned at a 45 degree angle to the outer side surface of the suction side to reduce stress on the tip rail. 
     
     
         4 . The turbine blade of  claim 1 , wherein the tip rail has a tip rail end in the midcord region of the suction side between the leading and trailing edges and the tip rail extends about a tip edge of the tip around the leading edge and along a portion of the pressure side, crossing over to the suction side downstream of the tip rail end of the squealer tip reform, extending along at least a portion of a tip edge of the tip along the suction side, extending toward the trailing edge and terminating at a second end. 
     
     
         5 . The turbine blade of  claim 4 , wherein the tip rail end of the tip rail is nonorthogonal and nonparallel to a tip edge of the suction side of the generally elongated blade. 
     
     
         6 . The turbine blade of  claim 5 , wherein the tip rail end of the tip rail is aligned with a span of the tip rail that extends past the tip rail end. 
     
     
         7 . The turbine blade of  claim 6 , wherein the tip rail extends from the leading edge to the suction side near the tip rail end of the tip rail. 
     
     
         8 . A turbine blade, comprising:
 a generally elongated blade having a leading edge, a trailing edge, a pressure side extending from the leading edge to the trailing edge, a suction side extending from the leading edge to the trailing edge and opposite to the pressure side, a tip at a first end, and a root coupled to the blade at an end generally opposite the first end for supporting the blade and for coupling the blade to a disc;   a tip rail coupled to the tip at the first end, extending radially outward and configured such that an outer surface of the tip rail is generally aligned with an outer side surface of the turbine blade defining a cross-sectional profile of the turbine blade for a portion of the outer side surface of the turbine blade, wherein a leading edge region recess is formed proximate to the leading edge between an inner edge of the tip rail on the suction side and an inner edge of the tip rail on the pressure side and defined by an outer surface of the tip of the generally elongated blade, and a trailing edge region recess is formed proximate to the trailing edge between an outer surface of the tip rail and a tip edge at an intersection between the outer side surface and the outer surface of the tip such that at least a portion of the tip edge at the pressure side is exposed without the tip rail;   wherein the tip rail includes a gap located adjacent to the suction side of the generally elongated blade to limit the formation of stress in the tip rail along the suction side;   wherein the gap in the tip rail is positioned in a midchord region of the suction side between the leading and trailing edges; and   wherein the tip rail is formed from at least one single crystal alloy oriented in a low modulus direction such that a gap exists at a location in the tip rail where the axis of orientation is positioned at a 45 degree angle to the outer surface of the suction side to reduce stress on the tip rail.   
     
     
         9 . The turbine blade of  claim 8 , wherein the tip rail has a tip rail end in the midcord region of the suction side between the leading and trailing edges and the tip rail extends about a tip edge of the tip around the leading edge and along a portion of the pressure side, crossing over to the suction side downstream of the tip rail end of the squealer tip reform, extending along at least a portion of a tip edge of the tip along the suction side, extending toward the trailing edge and terminating at a second end. 
     
     
         10 . The turbine blade of  claim 9 , wherein the tip rail end of the tip rail is nonorthogonal and nonparallel to a tip edge of the suction side of the generally elongated blade. 
     
     
         11 . The turbine blade of  claim 10 , wherein the tip rail end of the tip rail is aligned with a span of the tip rail that extends past the tip rail end. 
     
     
         12 . The turbine blade of  claim 11 , wherein the tip rail extends from the leading edge to the suction side near the tip rail end of the tip rail. 
     
     
         13 . A component for a turbine blade, comprising:
 a tip rail configured to be coupled to a tip of a gas turbine airfoil;   wherein the tip rail extends radially outward and is configured such that an outer surface of the tip rail is generally aligned with an outer side surface of the turbine blade defining a cross-sectional profile of the turbine blade for a portion of the outer side surface of the turbine blade, wherein a leading edge region recess is formed between an inner edge of the tip rail on a suction side of the airfoil and an inner edge of the tip rail on a pressure side of the airfoil, and a trailing edge region recess is formed proximate to a trailing edge between an outer surface of the tip rail and a tip edge at an intersection between the outer side surface and the outer surface of the tip of the airfoil such that at least a portion of the tip edge at the pressure side is exposed without the tip rail;   wherein the tip rail includes a gap located adjacent to the suction side of the airfoil to limit the formation of stress in the tip rail along the suction side;   wherein the gap in the tip rail is positioned in a midchord region of the suction side between the leading and trailing edges; and   wherein the tip rail is formed from at least one single crystal alloy oriented in a low modulus direction such that a gap exists at a location in the tip rail where the axis of orientation is positioned at a 45 degree angle to the outer surface of the suction side to reduce stress on the tip rail.   
     
     
         14 . The component of  claim 13 , wherein the tip rail has a tip rail end in the midcord region of the suction side between the leading and trailing edges and the tip rail extends about a tip edge of the tip around the leading edge and along a portion of the pressure side, crossing over to the suction side downstream of the tip rail end of the squealer tip reform, extending along at least a portion of a tip edge of the tip along the suction side, extending toward the trailing edge and terminating at a second end. 
     
     
         15 . The component of  claim 14 , wherein the tip rail end of the tip rail is nonorthogonal and nonparallel to a tip edge of the suction side of the airfoil. 
     
     
         16 . The component of  claim 15 , wherein the tip rail end of the tip rail is aligned with a span of the tip rail that extends past the tip rail end. 
     
     
         17 . The component of  claim 16 , wherein the tip rail extends from the leading edge to the suction side near the tip rail end of the tip rail.