Flat-plate film cooling from a double jet holes: influence of free-stream turbulence and flow acceleration

Results of an experimental study of flat-plate film cooling effectiveness achieved with an inlet double jet scheme are reported. At low (m = 0.5) and medium (m = 1.0) blowing ratio the average film cooling effectiveness is about 20 % greater of the traditional two-row scheme of round holes data, while at higher m = 1.5 it is close to it. The free-stream turbulence (≈ 7 %) influences weekly on the average flat-plate film cooling effectiveness. The flow acceleration decreases the film cooling effectiveness down to 25 % when the pressure gradient parameter K is ranged from 0.5·10−6 to 3.5·10−6.