Patent ID: 7442007

Claim:
A turbine rotor assembly of a gas turbine engine, comprising: a rotor disc having a plurality of blade attachment slots defined through a periphery of the disc; an array of rotor blades extending outwardly from the blade attachment slots in the periphery of rotor disc, each of the rotor blades including an airfoil section having internal cooling passages therein, lobed blade root having an opening in communication with said cooling passages, and a platform extending laterally from the airfoil section, each blade root being disposed within a corresponding blade attachment slot, lobes of each respective blade root being received within mating anti-lobe portions of each respective slot, the mating lobes and anti-lobes extending axially in a radial plane of the turbine rotor assembly at an acute angle towards a longitudinal axis of the turbine rotor assembly, a cavity being defined between a bottom surface of the blade root and a floor of the corresponding attachment slot spaced apart from said bottom surface, the cavity in air flow communication with said opening; and wherein the blade root bottom surface extends generally towards the floor of the attachment slot so that the cavity is axially tapered towards said opening.