Bell-shaped film cooling holes for turbine airfoil

摘要

A turbine airfoil (22) having an external surface defining a curvature, and including a leading edge (26) and an axially spaced-part trailing edge (28), the leading edge (26) having an axially-extending aerodynamic external surface curvature. A plurality of cooling holes (50) are formed in the external surface of the airfoil (22) in fluid communication with the cooling circuit (40), at least some of the plurality of cooling holes (50) having a metering section (58) downstream of the cooling circuit (40), and a diffuser section (51). The side walls and one or the other of the top and bottom walls (55, 56) of the diffuser section (51) have a bell-shaped configuration for achieving a flow of the cooling film from the cooling circuit (40) with enhanced spread, enhanced attachment and less turbulence to a downstream surface of the airfoil (22) local to each respective cooling hole (50).