Diaphragm and blades for turbomachinery

Abstract

A diaphragm for an axial flow turbomachine, in which outer shrouds of adjacent fixed blades in a row of blades contact each other circumferentially to form a circumferentially continuous load path. Inner shrouds of the blades only contact each other on contact faces oriented to transmit loads in the radial and/or axial directions of the turbomachine.

1 . A blade for use in a row of fixed blades in an axial flow turbomachine, comprising:
 (a) a radially outer shroud portion,   (b) a blade aerofoil portion, and   (c) a radially inner shroud portion having two opposed side edges for contacting corresponding side edges of adjacent inner shroud portions of adjacent blades in a row of such blades,   wherein each opposed side edge comprises a projecting step portion, a recessed step portion and a chamfered step portion that joins the projecting step portion to the recessed step portion, the projecting step portions being at opposite ends of their respective side edges and configured to project into co-operating recessed step portions of adjacent inner shroud portions of adjacent blades, the chamfered step portions being arranged to transfer forces between adjacent inner shroud portions transversely of the circumferential direction in the row of blades and to prevent circumferential transmission of loads between adjacent inner shroud portions.   
   
   
       2 . A blade according to  claim 1 , wherein each opposed side edge of the inner shroud portion further comprises a planar portion, and wherein the projecting step portions comprise parts of the side edges that jut out relative to the planar portions, and the recessed step portions comprise parts of the side edges that are undercut relative to the planar portions. 
   
   
       3 . A blade according to  claim 2 , wherein contact faces of the planar portions, the projecting step portions and the recessed step portions are arranged to radially abut each other in the row of blades, thereby to transfer radial forces between adjacent inner shroud portions. 
   
   
       4 . A blade according to  claim 1 , the blade being a steam turbine blade. 
   
   
       5 . A blade according to  claim 1 , the blade being a gas turbine blade or a compressor blade. 
   
   
       6 . A diaphragm for an axial flow turbomachine, comprising:
 outer shrouds of adjacent fixed blades in a row of blades which contact each other circumferentially to form a circumferentially continuous load path; and   inner shrouds of the blades which only contact each other on contact faces oriented to transmit loads in a radial and/or axial direction of the turbomachine.   
   
   
       7 . A diaphragm according to  claim 6 , in which there is an interference fit between adjacent inner shrouds on their contact faces, and the interference fit applies sufficient torque forces to the shrouds to ensure that the contact faces remain in contact with each other throughout operation of the turbomachine. 
   
   
       8 . A diaphragm according to  claim 6 , wherein the contact faces for transmitting loads in radial directions contact each other when the diaphragm is in the as-assembled cool condition and throughout all operating conditions of the turbine, but the contact faces for transmitting loads in axial directions only contact each other when the diaphragm reaches an operating temperature. 
   
   
       9 . A diaphragm according to  claim 6 , wherein opposed side edges of the inner shrouds contact corresponding side edges of adjacent inner shrouds of adjacent blades and each opposed side edge comprises a projecting step portion, a recessed step portion and a chamfered step portion that joins the projecting step portion to the recessed step portion, the projecting step portions being at opposite ends of their respective side edges and configured to project into co-operating recessed step portions of adjacent inner shrouds of adjacent blades, the chamfered step portions comprising contact faces operative to transmit loads in axial directions between adjacent inner shroud portions and to prevent circumferential transmission of loads between adjacent inner shroud portions. 
   
   
       10 . A diaphragm according to  claim 9 , wherein each opposed side edge of the inner shroud portion further comprises a planar portion, and wherein the projecting step portions comprise parts of the side edges that jut out relative to the planar portions, and the recessed step portions comprise parts of the side edges that are undercut relative to the planar portions. 
   
   
       11 . A diaphragm according to  claim 10 , wherein contact faces of the planar portions, the projecting step portions and the recessed step portions are arranged to radially abut each other, thereby to transfer radial forces between adjacent inner shroud portions. 
   
   
       12 . A steam turbine diaphragm according to  claim 6 , in combination with a steam turbine. 
   
   
       13 . A diaphragm according to  claim 6 , in combination with a gas turbine or compressor. 
   
   
       14 . A turbine including a diaphragm according to  claim 6 . 
   
   
       15 . A compressor including a diaphragm according to  claim 6 .