A combustion turbine 20 includes a housing 22 and a plurality of airfoils
40 within the housing. Each airfoil 40 has a leading edge surface 42 and
at least one interior cooling passageway 44. A plurality of diffusion
holes 46 extend from the at least one interior cooling passageway 44 to
the leading edge surface 42. Each diffusion hole 46 includes a proximal
section 48 having a generally constant cross-sectional shape and a distal
tapered section 50 that extends outwardly from the proximal section,
tapering in a radially inward direction.
