Serpentine cooling circuit and method for cooling tip shroud

A turbine rotor having a row of turbine blades, at least one of said turbine blades comprising:

• a root portion for fixing said blade to said turbine rotor;
• an airfoil portion extending longitudinally from said root;
• at least one airfoil cooling passage extending through said airfoil, said airfoil cooling passage having an inlet for receiving a flow of cooling fluid;
• a shroud projecting outwardly from said airfoil and having a radially inward facing surface;
• and
• at least one serpentine cooling passage defined to extend back and forth through at least a portion of said shroud, said serpentine cooling passage being in flow communication with said airfoil cooling passage so as to receive cooling fluid therefrom and including at least one outlet opening for spent cooling fluid to exit the shroud,
• whereby at least a first portion of said cooling fluid received by said airfoil cooling passage through said inlet thereof flows into and through said serpentine cooling passage, and exits through said at least one outlet opening,
• wherein said shroud includes at least one center cooling chamber, said center cooling chamber being in flow communication with said at least one airfoil cooling passage and being in flow communication with said at least one serpentine cooling passage.

A method of cooling a gas turbine airfoil having an associated substantially planar shroud extending in a plane substantially perpendicular to the airfoil, the method comprising:

• a) providing at least one airfoil cooling passage in said airfoil;
• b) providing at least one center cooling chamber in said shroud;
• c) providing at least one serpentine cooling passage in said shroud that extends back and forth through at least a portion of said shroud;
• d) supplying cooling air to said at least one airfoil cooling passage;
• e) channeling said cooling air to said at least one serpentine cooling passage in said shroud;
• and
• f) passing said cooling air through said at least one serpentine cooling passage and out through said shroud,
• wherein said center cooling chamber is in flow communication with said at least one airfoil cooling passage and is in flow communication with said at least one serpentine cooling passage.