Patent ID: 6203273
Filing Date: 2001-03-20
Classification: F01D,Y02T

Abstract:
An axial flow gas turbine engine having an axis of rotation Ar which includes a compressor having a flow path for working medium gases, the flow path having a mean flow line in the compressor which converges radially inwardly with a negative slope whose absolute value is greater at the aft region of the compressor than the mid-region of the compressor, and a bearing for supporting a rotor assembly, which comprises:a rotor assembly havinga rotor member supported from the bearing,a plurality of rotor blades extending outwardly from the rotor member, andat least one knife edge seal element disposed on the rotor member, extending circumferentially about the rotor member and extending outwardly from the rotor members;a stator assembly which extends circumferentially about the rotor assembly which includes,at least one circumferentially extending seal land disposed radially outward of each of said knife edge seal elements and at least one circumferentially extending rubstrip disposed radially outward of each of said arrays of rotor blades, the first rubstrip being disposed outwardly of the first array of rotor blades, each seal land and rubstrip having an associated average diameter Dav in the non-operative condition at the first axial location, the rubstrip being disposed about said array of rotor blades and extending rearwardly at about the same angle as the tip of the rotor blade and being radially oriented with respect to the airfoil tip with a nominal clearance dimension and a tolerance band having a minimum clearance dimension and a maximum clearance dimension, andan outer case which engages each rubstrip to support and position the rubstrip such that the rubstrip is not a perfect circle at the first axial location;wherein the rotor blade has a stacking line S and the first axial location is axially aligned with the intersection of the stacking line S with the tip of the rotor blade and wherein the rotor blade and the rubstrip at the average diameter Dav have an interference fit at the minimum clearance dimension with the average diameter Dav of the rubstrip in the non-operative condition;wherein the clearance between said rotor blade and said rubstrip of the outer air seal increases under operative conditions and the arrays of rotor blades move axially forwardly toward the bearing and away from the frustoconical outer air seal; and,wherein the clearance is smaller than if the same tolerance band were used and the minimum clearance was not an interference fit at said first axial location.