Turbine blade cooling

Abstract

A blade includes a root and an elongate portion extending to a tip, the elongate portion having an aerofoil-shaped cross-section. The aerofoil has leading and trailing edges, and suction and pressure sides. The tip includes a squealer defining a gutter at the tip, the squealer extending from the trailing edge along the entirety of a first of the suction and pressure sides, around the leading edge and partly along a second of the suction and pressure sides leaving a gap between the trailing edge and an end of the wall. A main trailing edge cooling channel extends within the elongate portion in a direction from root to tip adjacent the trailing edge and exits into the gutter. The main trailing edge cooling channel includes a bend just downstream of the exit, the exit displaced from a camber line of the blade elongated portion towards the second side.

We claim: 
     
         1 . A blade comprising a root portion and an elongate portion extending from the root portion to a tip, the elongate portion having an aerofoil-shaped cross section having a leading edge, a trailing edge, a suction side and a pressure side, the tip including a squealer defining a gutter at the tip wherein the squealer comprises a wall extending from the trailing edge along the entirety of a first of the suction side and pressure side, around the leading edge and partly along a second of the suction side and pressure side leaving a gap between the trailing edge and an end of the wall on the second side, a main trailing edge cooling channel extending within the elongate portion in a direction from root to tip adjacent the trailing edge and exiting into the gutter, wherein the main trailing edge cooling channel includes a bend just upstream of the exit such that the exit is displaced from a camber line of the blade elongated portion towards the second side. 
     
     
         2 . A blade as claimed in  claim 1  wherein the first side is the pressure side and the main trailing edge cooling channel bends towards the suction side. 
     
     
         3 . A blade as claimed in  claim 1  wherein the first side is the suction side and the main trailing edge cooling channel bends towards the pressure side. 
     
     
         4 . A blade as claimed in  claim 1  wherein the gutter is shallower adjacent the leading edge than it is at the trailing edge. 
     
     
         5 . A blade as claimed in  claim 1  wherein the gutter in the region of the trailing edge is inclined from the first side towards the second side whereby to maintain a surface which is substantially orthogonal to the walls of the main trailing edge cooling channel where they meet the gutter. 
     
     
         6 . A blade as claimed in  claim 1  further comprising a gallery channel integrally cast into the blade using an adapted core which defines both the main trailing edge cooling channel and has an extension defining the gallery channel. 
     
     
         7 . A blade as claimed in  claim 5  wherein the gallery channel is provided in a shape which minimises flow restriction in the gallery channel. 
     
     
         8 . A blade as claimed  claim 5  wherein the gallery channel is spout shaped having a larger diameter at an open end where it intersects the main trailing edge cooling channel and a smaller diameter at a closed end which sits just behind an apogee of the trailing edge. 
     
     
         9 . A blade as claimed in  claim 5  wherein a tip facing surface of the gallery channel is profiled to complement and extend in parallel with the surface of the gutter in the trailing edge region. 
     
     
         10 . A blade as claimed in  claim 5  wherein the gallery channel is shaped to follow variations in the depth of the gutter. 
     
     
         11 . A blade as claimed in  claim 5  further comprising an array of film cooling channels extending from the gallery channel and through the squealer wall. 
     
     
         12 . A blade as claimed in  claim 1  wherein the depth of the squealer wall varies from a first depth at the leading edge to a second and greater depth at the trailing edge. 
     
     
         13 . A blade as claimed in  claim 1  wherein the width of the squealer wall is variable. 
     
     
         14 . A blade as claimed in  claim 13  wherein the width of the squealer wall reduces from a maximum width at a first end of the squealer wall to a minimum width at a second end of the squealer wall. 
     
     
         15 . A blade as claimed in  claim 1  wherein the squealer wall includes a locally extended portion adjacent the trailing edge on the first side, the extended portion extending in a widthwise direction with respect to the squealer wall and away from the gutter. 
     
     
         16 . A blade as claimed in  claim 1  configured for use in a gas turbine engine.