Rotor blade with cooled integral platform

A rotor assembly for a gas turbine engine disposed about a longitudinal axis, the gas turbine engine including an axially directed flowpath defining a passage for working fluid and a source of cooling fluid, the rotor assembly including:

• a rotatable disk;
• and
• a plurality of rotor blades, wherein each of the plurality of rotor blades includes:
• an airfoil section extending through the flow path, the airfoil portion including a pressure surface and a suction surface, the airfoil portion having a hollow core;
• a root portion disposed radially inward of the airfoil portion and engaged with the disk to secure the blade to the disk, the root portion including a core path defining a flow path for cooling fluid, the core path being in fluid communication with the source of cooling fluid and with the hollow core of the airfoil portion;
• and a platform extending laterally from the blade and disposed radially between the airfoil portion and the root portion, the platform including an outer surface defining a flow surface for the flow path, a first fillet adjoining the outer surface and the airfoil portion, an inner surface defining in part an under platform cavity, and a second fillet adjoining the inner surface and the root portion;
• and
• wherein a first cooling hole extends between the core path and the outer surface, the first cooling hole being disposed radially inward of the first fillet and radially outward of the second fillet, the first cooling hole having an inlet disposed in the core path and an exit disposed on the outer surface and laterally outward of the first fillet, and wherein a second cooling hole extends between the under platform cavity and the outer surface, the second cooling hole including an inlet disposed on the inner surface and an exit disposed on the outer surface, the second cooling hole exit disposed laterally outward of the first cooling hole exit.