Rim seal

Abstract

A rim seal between a stator and a rotor in a gas turbine engine is described. The seal includes an axial overlap between platform rims of the stator and the rotor. The axial length of the platform rim of one of the stator and the rotor is accommodated within a radially aligned trench defined in the other of the stator and the rotor.

1 . A method of forming a rim seal between a rotor and a stator of a gas turbine engine, comprising:
 obtaining a rotor having a rotor disk rotatable about a longitudinal axis and having rotor blades protruding from rotor platforms, the rotor blades located radially outwardly of the rotor disk;   obtaining a stator having vanes protruding from stator platforms;   moving the rotor and the stator toward one another in an axial direction relative to the longitudinal axis until rotor flanges defined by the rotor platforms axially overlap stator flanges defined by the stator platforms; and   further moving the rotor and stator toward one another in the axial direction to decrease an axial distance between ends of the stator platforms and bases of trenches defined by the rotor platforms, the bases of the trenches located axially closer to an axial centerline plane of the rotor disk than are upstream and downstream faces of the rotor disk.   
     
     
         2 . The method of  claim 1 , wherein further moving the rotor and stator toward one another includes moving the stator and rotor toward one another until an axial overlap distance between the stator platforms and the rotor platforms is greater than or equal to a radial gap distance between the rotor flanges and the stator flanges. 
     
     
         3 . The method of  claim 2 , wherein moving the stator and rotor toward one another includes moving the stator and rotor toward one another until the axial overlap distance is equal to the radial gap distance. 
     
     
         4 . The method of  claim 1 , wherein further moving the rotor and stator toward one another in the axial direction includes moving the rotor and stator toward one another until an axial overlap distance between the stator platforms and the rotor platforms is greater than an axial depth of the trenches, the axial depth defined between the bases of the trenches and an axially outer face of the rotor platform. 
     
     
         5 . The method of  claim 1 , wherein further moving the rotor and stator toward one another in the axial direction includes moving the rotor and stator toward one another until an axial overlap distance between the stator platforms and the rotor platforms is greater than an axial distance between the ends of the stator platforms and an axially outer face of the rotor platform. 
     
     
         6 . The method of  claim 1 , wherein further moving the rotor and stator toward one another in the axial direction includes moving the rotor and stator toward one another until an axial overlap distance between the stator platforms and the rotor platforms is greater than an axial distance between the ends of the stator platforms and a closest one of the upstream and downstream faces of the rotor disk. 
     
     
         7 . The method of  claim 1 , wherein further moving the rotor and stator toward one another in the axial direction includes moving the rotor and stator toward one another until an axial overlap distance between the stator platforms and the rotor platforms is greater than the axial distance between the ends of the stator platforms and the bases of the trenches. 
     
     
         8 . The method of  claim 1 , wherein the blades and the vanes are turbine blades and turbine vanes. 
     
     
         9 . The method of  claim 1 , including radially aligning the stator flanges with the trenches. 
     
     
         10 . A method of forming a rim seal between a rotor and a stator of a gas turbine engine, the stator being axially spaced apart from the rotor immediately downstream therefrom, the rotor including a set of blades having blade platforms mounted to a rotor disk rotatable about a longitudinal axis, the blades located radially outwardly of the rotor disk, the method comprising:
 axially overlapping an annular rotor rim extending axially downstream from the blade platforms of the rotor and an annular stator rim extending axially upstream from the stator by an axial overlap distance;   increasing the axial overlap distance by increasing an axial length of the annular stator rim; and   forming a trench in the blade platforms of the rotor to accommodate the increased axial length of annular stator rim, the trench being radially aligned with the annular stator rim, the trench extending axially into the blade platforms to define an axial depth between a base of the trench and an axially outer surface of the blade platforms, the base of the trench being axially further upstream than a downstream face of the rotor disk at a radially outer rim thereof.   
     
     
         11 . The method of  claim 10 , further comprising providing the improved rim seal with a ratio of the axial overlap distance to a radial gap distance of equal to or greater than 1, the radial gap distance extending radially from the annular stator rim and the annular rotor rim. 
     
     
         12 . The method of  claim 10 , wherein forming the trench includes making the axial depth of the trench less than the axial overlap distance. 
     
     
         13 . The method of  claim 10 , wherein axially overlapping the annular rotor rim and the annular stator rim includes forming the axial overlap distance to be greater than an axial distance between a remote end of the stator rim and the axially outer surface of the rotor platform. 
     
     
         14 . The method of  claim 10 , wherein axially overlapping the annular rotor rim and the annular stator rim includes forming the axial overlap distance to be greater than an axial distance between a remote end of the stator rim and the downstream face of the rotor disk. 
     
     
         15 . The method of  claim 10 , wherein axially overlapping the annular rotor rim and the annular stator rim includes forming the axial overlap distance to be greater than an axial distance between a remote end of the stator rim and the base of the trench. 
     
     
         16 . The method of  claim 10 , wherein the blades are turbine blades.