US Patent 7168921 Cooling system for an airfoil

The cooling system for the airfoil includes forward and aft cooling circuits supplied with a cooling medium. Both circuits include serpentine passages. A central rib divides the forward and aft cooling circuits and includes an opening adjacent the airfoil tip providing a jet of the cooling medium from the forward cooling circuit for impingement against the aft portion of the tip cap. The tip cap also includes a thermal barrier coating along an outside surface thereof as well as on the seat for the tip cap, thereby lowering the tip cap metal temperature and thermally induced stress.