Coolant passages with full coverage film cooling slot

Claim 1

A hollow airfoil for a turbomachine, said airfoil being adapted to be disposed in a stream of hot gases flowing in a downstream direction, said airfoil comprising an external wall defining an external pressure surface and external suction surface of said airfoil over which said hot gases flow in said downstream direction, said external wall also having an internal surface defining a portion of a longitudinally extending coolant compartment within said airfoil for receiving cooling air, said external wall including a longitudinally extending slot formed in one of said external surfaces thereof, said slot having a forward wall surface, a rearward wall surface facing said forward wall surface, and a base, said base extending between said rearward and forward surfaces and located within said external wall, said forward and rearward wall surfaces each intersecting said one external surface of said airfoil external wall at a shallow angle for directing cooling fluid downstream over said one external surface and defining a longitudinally extending upstream edge and downstream edge, respectively, of an outlet of said slot, said external wall including a plurality of longitudinally spaced apart cooling air passages, each passage having an inner portion in fluid communication with said coolant compartment for receiving coolant fluid therefrom and for metering the flow of coolant through said passage, said inner portion being immediately followed by an outer portion in series flow relation thereto intersecting said slot base, said outer portion including spaced apart, facing end wall surfaces diverging from each other in the longitudinal direction toward said slot base, adjacent end wall surfaces of adjacent passages substantially meeting each other at said slot base, each passage outer portion also including a pair of spaced apart, facing side wall surfaces parallel to said longitudinal direction and joining said diverging end wall surfaces, wherein, at said slot base, a first of said pair of side wall surfaces joins with said slot forward wall surface, and said other of said pair of side wall surface joins with said slot rearward wall surface.