This paper investigated numerically the effect of a coolant crossflow on film cooling effectiveness.Computations were performed to investigate the three-dimensional film cooling flow and cooling effectiveness with two crossflow ratios(Cr=0.39

0.78) and two blowing ratios(Br=1

2) and two length to diameter ratios(l/d=4

8).The results of the present investigation show that there is a profound effect of how the coolant is supplied to the hole on the film-cooling performance in the near hole region

for example

crossflow ratio has great influence on the film-cooling effectiveness of surface

a bigger length to diameter ratio brings about regular flow within film holes

and a bigger blowing ratio leads to poorer adhesion of jet stream and lower film-cooling effectiveness.Therefore

crossflow at the hole entry side has to be taken into account when modeling film-cooling schemes of turbine blades.