Patent ID: 8708656
Filing Date: 2014-04-29
Classification: F01D,F05D

Abstract:
1. A fan rotor assembly of a gas turbine engine, comprising a disk mounted for rotation about a centerline of the engine, an array of circumferentially distributed dovetail slots defined in an outer periphery of the disk, a corresponding array of fan blades attachable to the disk, each fan blade having a blade dovetail engageable in a corresponding one of the dovetail slots, the blade dovetail having high stress regions and low stress regions, the low stress regions having a sacrificial bumper which will wear in preference to the high stress regions of the blade dovetail, the sacrificial bumper providing for a closer tolerance fit of the low stress regions of the blade dovetail in the dovetail slots than the high stress regions, thereby shielding the high stress regions from rubbing against the disk when the rotational speed of the turbofan assembly is too low to centrifugally lock the fan blades in position on the disk, wherein each dovetail slot has a pair of outer overhanging lugs having radially inwardly facing bearing surfaces for engagement with corresponding bearing surfaces provided on opposed flanks of each blade dovetail, wherein the sacrificial bumper comprises a pair of bumper surfaces provided on each blade dovetail radially outwardly of the bearing surfaces thereof for engaging corresponding bumper surfaces provided at a mouth of each dovetail slot, wherein the bumper surfaces of the blade dovetails and the bumper surfaces of the dovetail slots are oriented to be in contact while the blades move radially inwardly and outwardly relative to the dovetail slots during windmilling, and wherein the high stress regions of the blade dovetails include a neck region disposed radially between the bumper surfaces and the bearing surfaces of the blade dovetails, the bumper surfaces shielding the neck region along a full axial extent thereof from contacting the disk when the fan rotor assembly rotates at low speed, and wherein contact points between the blade dovetails and the disk during windmilling are in the low stress regions only.