Film-Cooling Performance of Multiple Arrays of Cylindrical and Fan-Shaped Holes

Experimental investigations are performed on the suction side of a cooled turbine guide vane. Transient infrared thermography is used to evaluate film-cooling performance of cylindrical and fan-shaped holes in a test facility representing engine conditions. Adiabatic film effectiveness and net heat flux reduction results due to coolant injection through double and multiple rows in the presence and absence of an upstream showerhead are presented. Two double staggered rows at different positions have been cross compared: one at a relatively high convex curvature region and the other close to the maximum throat velocity. A combination of the two double rows is considered to be multiple rows. The tested blowing ratios are in the interval of [0.6–1.2] and [0.3–1.2] for double and multiple rows, respectively. The showerhead cooling is maintained at a nominal blowing ratio. The findings suggest that the choice of best cooling hole shape for film-cooling design can be highly influenced by the number of cooling rows to be used and also the presence (or absence) of showerhead cooling. It is worth noting that the outcome may differ depending on the quantity of interest (i.e., adiabatic film effectiveness or net heat flux reduction).