Abstract: A gas turbine engine airfoil includes an airfoil outer wall having widthwise spaced apart pressure and suction sidewall sections extending chordally between leading and trailing edges of the airfoil and extending longitudinally from a base to a tip. Inside the airfoil is at least one internal cooling circuit having a plurality of longitudinally extending circuit channels between longitudinally extending internal ribs extending widthwise between the pressure and suction sidewall sections and a longitudinally extending first sidewall film cooling chamber positioned between one of the sidewall sections and a first inner wall bounding the cooling circuit. Sidewall film cooling holes extend through the pressure sidewall section from the first sidewall film cooling chamber.

Abstract: An aft entry system in a gas turbine engine is provided for cooling selected one or more of aft high and low pressure turbine stages of the engine. The aft entry system includes an air flow circuit for routing low pressure cooling air radially outward from an interstage region of a multi-stage compressor of a core engine of the gas turbine engine and axially in an aft direction to a plurality of radial passages, such as provided by stationary stator and outlet guide vanes, which provide an aft entry region to the selected high and low pressure turbine stages. The pressure of the cooling air routed by the air flow circuit of the aft entry system can be lower than the pressure of air at a discharge end of the compressor but higher than the pressure of the gas stream discharging from the selected turbine stage.