The performance of flat surface film cooling with 30° film cooling holes along streamwise was experimentally investigated using thermal liquid crystal.The temperature fields of adiabatic wall and conductive wall were measured.The effects of blow ratio and rows on film cooling effectiveness and heat transfer coefficient was studied.The results show that:blow ratio is a main influential factor to the film cooling effectiveness

the film cooling effectiveness decreases with the increasing of blow ratio;the film cooling effectiveness of discrete holes fluctuate dramatically across the transverse section

and dead zone is prone to occur between two discrete holes.TLC technique can be successfully applied to reflect film cooling effectual area and cooling effect.