US Patent 7097419 Common tip chamber blade

A turbine blade includes an airfoil having pressure and suction sidewalls spaced apart between opposite leading and trailing edges and interconnected by a plurality of partitions to define first and second independent cooling circuits therein. The cooling circuits have corresponding inlets in a dovetail of the blade and extend through a platform of the blade and through the airfoil to its tip. A common discharge chamber is disposed below the airfoil tip and includes a plurality of outlet holes for discharging cooling air from the circuits.