Film cooling is a major component of the overall cooling of turbine airfoils. An
example of a fi lm cooled turbine vane is shown in fi gure 1
1
. From the schematic of the
airfoil in fi gure 1, it is evident that there are holes placed in the body of the airfoil to
allow coolant to pass from the internal cavity to the external surface. The ejection of
coolant gas through holes in the airfoil body results in a layer or “fi lm” of coolant gas
fl owing along the external surface of the airfoil. Hence the term “fi lm cooling” is used to
describe the cooling technique. Since this coolant gas is at a lower temperature than the
mainstream, the heat transfer into the airfoil is reduced. The adiabatic fi lm effectiveness
has a predominant effect in the design of the overall airfoil cooling. Consequentially, in
this section details of fi lm cooling performance are reviewed