US Patent 7300252 Gas turbine airfoil leading edge cooling construction

A gas turbine airfoil with a pressure sidewall (6) and a suction sidewall (7) extends from a root (2) to a tip (3) and from a leading edge (4) to a trailing edge (5). It comprises several film cooling holes with exit ports (8). The film cooling holes have a sidewall that is diffused in the direction of the tip (3) of the airfoil (1) at least over a part of the film cooling hole. Furthermore, the film cooling holes each have flare-like contour near the outer surface of the leading edge (4). The film cooling holes according to the invention provide an improved film cooling effectiveness due to reduced formation of vortices and decreased penetration depth of the cooling air film.