Asymmetrical Compound-Angle on Combined-Hole Film Cooling

Abstract

In a modern gas turbine, a film cooling system was applied to provide thermal
protection on the turbine components due to high turbine inlet temperatures.
Enhanced film cooling effectiveness was formed through the combined-hole film
cooling with various parameters. Due to limited research on the asymmetrical
compound-angle, γ1 / γ2 on the combined-hole film cooling, the present work was
worked on it. The effect of distance between two combined-holes in mainstream
direction, LoD and different blowing ratio, M also covered in this work. All considered
cases were simulated and the best arrangement of combined-hole film cooling will be
determined. Based on different geometrical parameters; LoD and γ1 / γ2 applied,
insignificant changes were observed. Meanwhile, a huge change was observed as the
blowing ratio increase. As been observed, lateral coverage film cooling effectiveness
was spread wider as blowing ratio increase but a drastic decrease of film cooling
effectiveness was occurred at further downstream due to early separation and lift-off
of the cooling air.