Aerofoil cooling arrangement

Abstract

An aerofoil, comprises: a wall comprising an external surface, and an internal surface defining a cavity for receiving a cooling fluid in use; a first trench formed in the external surface, and a second trench formed in the external surface; a first passageway extending from a first passageway inlet in the cavity to a first passageway outlet in the first trench, and a second passageway extending from a second passageway inlet in the cavity to a second passageway outlet in the second trench; wherein the first passageway and second passageway intersect within the wall.

We claim: 
     
         1 . An aerofoil, comprising:
 a wall comprising an external surface, and an internal surface defining a cavity for receiving a cooling fluid in use;   a first trench formed in the external surface, and a second trench formed in the external surface;   a first passageway extending from a first passageway inlet in the cavity to a first passageway outlet in the first trench, and   a second passageway extending from a second passageway inlet in the cavity to a second passageway outlet in the second trench;   wherein the first passageway and second passageway intersect within the wall.   
     
     
         2 . The aerofoil as claimed in  claim 1 , wherein the first trench is formed in the external surface at a first trench location, and the second trench is formed in the external surface at a second trench location, wherein the first trench location and the second trench location are located either side of a stagnation point. 
     
     
         3 . The aerofoil as claimed in  claim 2 , wherein the first trench location and the second trench location are located adjacent the stagnation point. 
     
     
         4 . The aerofoil as claimed in  claim 2 , wherein the wall comprises a thickened region adjacent the first and second location, comprising a wall thickness which is greater than the wall thickness at a pressure or suction surface of the aerofoil. 
     
     
         5 . The aerofoil as claimed  claim 1 , wherein the first passageway comprises a first longitudinal axis, and the second passageway comprises a second longitudinal axis. 
     
     
         6 . The aerofoil as claimed in  claim 5 , wherein the first longitudinal axis and the second longitudinal axis extend in a chordwise direction. 
     
     
         7 . The aerofoil as claimed in  claim 5 , wherein the first longitudinal axis intersects a first tangent of the external surface at the first location, and the second longitudinal axis intersects a second tangent of the external surface at the second location at respective first angles, to provide the first passageway with a downstream trajectory relative to the first tangent, and the second passageway with a downstream trajectory relative to the second tangent. 
     
     
         8 . The aerofoil as claimed in  claim 7 , wherein the respective second angles are greater than the respective first angles, relative to the respective first and second tangents. 
     
     
         9 . The aerofoil as claimed in  claim 1 , wherein the first and second trenches comprise respective laidback second sidewalls downstream of the respective passageway outlets. 
     
     
         10 . The aerofoil as claimed in  claim 9 , wherein a tangent of the second sidewall of the first trench intersects the first tangent of the external surface at the first location, and a tangent of the second sidewall of the second trench intersects the second tangent of the external surface at the second location at respective second angles, to provide the respective second sidewalls with a downstream trajectory relative to the respective first and second tangents. 
     
     
         11 . The aerofoil as claimed in  claim 1 , wherein the first and second passageways comprise both a first major axis and a first minor axis adjacent the respective passageway inlets, and both a second major axis and a second minor axis adjacent the respective passageway outlets, wherein the second major axes adjacent the respective passageway outlets are greater than the first major axes adjacent the respective passageway inlets. 
     
     
         12 . The aerofoil as claimed in  claim 11 , wherein the first and second passageways terminate in a divergent profile adjacent the respective passageway outlets. 
     
     
         13 . The aerofoil as claimed in  claim 1 , wherein the first and second trenches comprise a trench depth which is equal to or less than the respective second major axes. 
     
     
         14 . The aerofoil as claimed in  claim 1 , wherein the first and second trenches comprise a trench width which is equal to or greater than the respective second major axes. 
     
     
         15 . A gas turbine engine comprising an aerofoil as claimed in  claim 1 . 
     
     
         16 . An aerofoil, comprising:
 a wall comprising an external surface, and an internal surface defining a cavity for receiving a cooling fluid in use;   a first trench formed in the external surface, and a second trench formed in the external surface;   a first passageway extending from a first passageway inlet in the cavity to a first passageway outlet in the first trench, and   a second passageway extending from a second passageway inlet in the cavity to a second passageway outlet in the second trench;   wherein the first passageway and second passageway intersect at an intersection point within the wall; and,   wherein the first passageway, second passageway and intersection point are each comprised within a single plane.