Abstract: A cast turbine blade is disclosed and includes an internal cooling passage that passes (e.g., zig-zags or meanders) through the blade from an inlet in the blade root to an outlet in the blade tip. The cooling passage can have a zone at a bend that is at a distance which is remote from the inlet of the cooling passage when the distance from the inlet is measured around the passage, but that is closer to the inlet when the distance from the inlet is measured in a straight line. During casting of the blade, the cooling passage can be defined by a core or cores having a leachable material, the cores being removed after casting by a chemical leaching process. A supplementary passage is also provided for connecting the remote zone to the inlet during the leaching process. The supplementary passage can likewise be defined by a leachable core, or it may be machined into the blade after casting.

Abstract: A cast turbine blade is disclosed and includes an internal cooling passage that passes (e.g., zig-zags or meanders) through the blade from an inlet in the blade root to an outlet in the blade tip. The cooling passage can have a zone at a bend that is at a distance which is remote from the inlet of the cooling passage when the distance from the inlet is measured around the passage, but that is closer to the inlet when the distance from the inlet is measured in a straight line. During casting of the blade, the cooling passage can be defined by a core or cores having a leachable material, the cores being removed after casting by a chemical leaching process. A supplementary passage is also provided for connecting the remote zone to the inlet during the leaching process. The supplementary passage can likewise be defined by a leachable core, or it may be machined into the blade after casting.