Patent ID: 8939715
Filing Date: 2015-01-27
Classification: F01D

Abstract:
1. A turbine bucket tip clearance control system comprising: a rotor assembly including a rotor having a plurality of axially spaced wheels, each of said axially-spaced wheels mounting an annular row of buckets, said annular row of buckets on at least one of said plurality of axially-spaced wheels having a radially outer tip shroud provided with at least one seal tooth; a stator assembly including a radially inwardly facing, axially-stepped surface arranged to be opposite the radial tip shroud provided on the at least one annular row of buckets, said axially-stepped surface comprising a first horizontal seal surface at a first distance from the tip shroud and a second horizontal seal surface at a second distance from the tip shroud, the first horizontal seal surface and the second horizontal seal surface are connected by a shoulder, the second distance is greater than the first distance; and the first horizontal seal surface and the second horizontal seal surface establish two different seal clearance gaps with said at least one seal tooth; and wherein said stator assembly and said rotor assembly are mechanically shiftable axially relative to each other, enabling selective shifting of said at least one seal tooth to a location radially opposite the first horizontal seal surface or the second horizontal seal surface to thereby enable selectively choosing of one or the other of said two different clearance gaps.