Blade Mounting

Abstract

The angular nature of corners 3 to roots 2 of a conventional blade 1 used in a gas turbine engine has resulted in relatively thick fan casings in order to contain any blade fragments from these corners 3 as a result of blade failure. By angling the end face 26 of the root 22 such that it is nearer to perpendicular to an axis of curvature 27 for a blade 21 the corners 23 are reduced in their angular nature. In such circumstances the potential for penetration of a fan casing through impingement with such corners 23 is reduced and the fan casing thickness can more confidently be thinned reducing overall weight. Furthermore by appropriate profiling of an aerofoil 24 adjacent to the front and trailing edges 20 of the aerofoil about the root 22 and face 26 further reductions in angular parts of the blade can be achieved.

1 . A blade for a gas turbine engine, the blade rotatable in use about an axis of rotation, the blade comprising a root for securing the blade, the root curved for alignment in use with a mounting slot, characterised in that an end of the root is substantially perpendicular to the axis of curvature of the root. 
     
     
         2 . A blade as claimed in  claim 1 , in which both ends of the root are substantially perpendicular to the axis of curvature of the root. 
     
     
         3 . A blade for a gas turbine engine, the blade rotatable in use about an axis of rotation, the blade comprising a root for securing the blade, the root curved for alignment in use with a mounting slot, characterised in that an end of the root makes an angle of substantially 25 degrees to the plane perpendicular to the axis of rotation. 
     
     
         4 . A blade as claimed in  claim 3 , in which both ends of the root make an angle of substantially 25 degrees to the plane perpendicular to the axis of rotation. 
     
     
         5 . A blade as claimed in  claim 1 , in which the blade comprises an aerofoil which extends from the root and a portion of the aerofoil adjacent to the end of the root is rounded so as to provide a smooth transition between the aerofoil and the end of the root. 
     
     
         6 . A blade as claimed in  claim 1 , in which at least one end of the root is chamfered or truncated, so as to reduce the axial length of the root. 
     
     
         7 . A gas turbine engine incorporating a blade as claimed in  claim 1 . 
     
     
         8 . A gas turbine engine incorporating a blade as claimed in  claim 2 . 
     
     
         9 . A gas turbine engine incorporating a blade as claimed in  claim 3 . 
     
     
         10 . A gas turbine engine incorporating a blade as claimed in  claim 4 . 
     
     
         11 . A gas turbine engine incorporating a blade as claimed in  claim 5 . 
     
     
         12 . A gas turbine engine incorporating a blade as claimed in  claim 6 .