Blades

Abstract

A rotor blade for a gas turbine engine has an aerofoil portion and a tip region. The tip region is at the radially outermost end of the blade. The radially outermost surface carries abrasive material (not shown) to interact with an abradable surface. The tip has a recess in which cooling air outlets are formed. The recess is open in a circumferential direction. This allows cooling air outlets to be formed without interference from the abrasive material, and inhibits any tendency for abrasion debris to collect in the recess and interfere with the flow of cooling air.

1 . A rotor blade having an aerofoil portion and a rotor tip at the radially outermost end of the blade, the tip having a recess in which cooling air outlets are formed, and the rotor tip includes at least one winglet which projects transversely to shroud the tip, and in which the recess is formed. 
     
     
         2 . A rotor blade according to  claim 1 , wherein the recess extends along an edge of the winglet. 
     
     
         3 . A rotor blade according to  claim 1 , wherein the recess is open in a circumferential direction. 
     
     
         4 . A rotor blade according to  claim 1 , wherein the recess is open toward the suction and/or the pressure side of the aerofoil portion. 
     
     
         5 . A rotor blade according to  claim 1 , wherein the radially outermost surface of the tip is associated, in use, with another surface to reduce leakage of combustion gases around the tip, one of the surfaces carrying abrasive material, and the other one of the surfaces being abradable. 
     
     
         6 . A rotor blade according to  claim 1 , wherein the recess is open at the radially outermost surface of the tip. 
     
     
         7 . A rotor blade according to  claim 1 , wherein the rotor tip is stepped back from the outermost surface of the tip to form the recess. 
     
     
         8 . A rotor blade according to  claim 1 , wherein the rotor tip is chamfered back from the outermost surface of the tip to form the recess. 
     
     
         9 . A rotor blade according to  claim 1 , wherein the rotor tip is curved from the outermost surface of the tip to form the recess. 
     
     
         10 . A rotor blade according to  claim 1 , wherein the rotor tip is undercut to form the recess. 
     
     
         11 . A rotor blade according to  claim 1 , wherein the recess extends continuously around the radially outermost surface of the tip. 
     
     
         12 . A rotor blade according to  claim 1 , wherein the radially outermost surface of the tip is a surface of the winglet. 
     
     
         13 . A rotor blade according to  claim 12 , wherein the recess extends around at least part of the outline of the winglet. 
     
     
         14 . A rotor blade according to  claim 1 , wherein the rotor tip has a gutter extending across the radially outermost surface of the tip, and the or each recess is open to one or more of the gutter, the pressure side and the suction side. 
     
     
         15 . A gas turbine engine comprising at least one rotor blade according to  claim 1 .