Turbine rotor blade platform cooling

A method of creating a platform cooling arrangement in a turbine rotor blade having a platform at an interface between an airfoil and a root, wherein the rotor blade includes an interior cooling passage formed therein that extends from a connection with a coolant source at the root to the platform, and wherein, along a side that coincides with a pressure side of the airfoil, a pressure side of the platform comprises a topside extending circumferentially from an airfoil base to a pressure side slashface, the method comprising the steps of:

• forming a main plenum in the pressure side of the platform via a casting process, the main plenum being configured to extend through the platform from an upstream end having an aft position to a downstream end having a forward position;
• and
• machining cooling apertures;
• wherein:
• near the upstream end, the main plenum includes an aft switchback, and, between the aft switchback and the downstream end, a forward arc;
• and
• each of the cooling apertures extends from the main plenum to a port formed on the pressure side slashface.