Platform seal strip, turbine blade assembly and method for assembling it

Abstract

A platform seal strip, in particular for use in a gas turbine blade assembly, is provided. The platform seal strip includes an upper side, a lower side, a first portion and a second portion. The width of the first portion is smaller than the width of the second portion. The first portion and the second portion are at least partially bent downwards such that the upper side includes a convex surface portion and the lower side includes a concave surface portion.

1 . A platform seal strip, comprising
 an upper side, a lower side, a leading portion and a second portion, the width of the leading portion being smaller than the width of the second portion,   wherein the leading portion and the second portion are at least partially bent downwards such that the upper side comprises a convex surface portion and the lower side comprises a concave surface portion.   
     
     
         2 . The platform seal strip as claimed in  claim 1 ,
 further comprising   a transition portion which is located between the leading portion and the second portion, wherein the width of the transition portion increases from the leading portion to the second portion.   
     
     
         3 . The platform seal strip as claimed in  claim 1 , wherein the strip seal comprises a trailing portion extending downwards from the second portion. 
     
     
         4 . The platform seal strip as claimed in  claim 1 , further comprising
 at least one nose located at the first portion or at the second portion which is at least partially bent upwards such that the upper side comprises a concave surface portion and the lower side comprises a convex surface portion.   
     
     
         5 . A turbine blade assembly comprising
 a number of platform seal strips as claimed in  claim 1 ,   a disc and a number of blades, each blade comprising a blade platform, wherein the blades are connected to the disc and each platform seal strip is placed in a gap between the blade platforms of adjacent blades.   
     
     
         6 . The turbine assembly as claimed in  claim 5 ,
 wherein the disc comprises a rotation axis and the platform of each blade comprises a side surface with a surface normal which includes a right angle with the rotation axis,   wherein the side surface comprises a slot and part of the second portion of the platform seal strip engages in the slot.   
     
     
         7 . The turbine assembly as claimed in  claim 6 ,
 wherein the platform comprises a main platform part and a leading wall and the slot extends along the main platform part and a leading wall.   
     
     
         8 . The turbine assembly as claimed in  claim 7 ,
 wherein the platform comprises a trailing wall and the slot extends along the main platform part and a trailing wall.   
     
     
         9 . The turbine assembly as claimed in  claim 5 ,
 wherein the disc comprises a front face and a rear face and a first cover plate is attached to the rear face and/or a second cover plate is attached to the front face and the platform seal strip comprises a nose which engages into a groove of the first cover plate or into a groove of the second cover plate.   
     
     
         10 . The turbine assembly as claimed in  claim 5 ,
 wherein only one platform seal strip is located between two adjacent blades.   
     
     
         11 . A gas turbine comprising a turbine blade assembly as claimed in  claim 5 . 
     
     
         12 . A method for assembling a turbine blade assembly as claimed in  claim 5 , comprising:
 loading the number of blades onto the disc leaving a gap between the platforms of adjacent blades,   inserting a platform seal strip into the gap between the platforms of two adjacent blades, and   retaining the platform seal strips by attaching a first cover plate to the disc.   
     
     
         13 . The method as claimed in  claim 12 , further comprising
 attaching a second cover plate to the disc before loading the blades onto the disc.   
     
     
         14 . The method as claimed in  claim 12 , further comprising
 using a platform seal strip having at least one nose located at the first portion or at the second portion which is at least partially bent upwards such that the upper side comprises a concave surface portion and the lower side comprises a convex surface portion and inserting the at least one nose into a groove in the first or second cover plate.   
     
     
         15 . The method as claimed in  claim 12 , further comprising
 positioning a seal means between the first cover plate and the disc and/or positioning a seal means between the second cover plate and the disc.   
     
     
         16 . The platform seal strip of  claim 1  adapted for use in a gas turbine blade assembly.