The effects of manufacturing tolerance on the film cooling effectiveness of a laidback fan-shaped hole

In modern gas turbines, film cooling have been widely applied to protect components from hot combustion gas. Recently, a laidback fan-shaped hole has been widely applied due to its high cooling performance. Generally, the cylindrical and diffuser components of the laidback fan-shaped hole are fabricated in separate manufacturing processes, and the manufacturing tolerance during these processes may cause imperfections in the hole shape. In this study, the laidback fan-shaped holes, which has five misalignment types, are experimentally investigated using the pressure sensitive paint technique. The lateral distance misalignment results in significantly decreased film cooling effectiveness (FCE), while the roll angle misalignment does not show a significant effect on FCE. The lateral angle misalignment also causes decreased FCE. The negative forward angle misalignment increased FCE. The vertical distance misalignment alters the flow separation region in the diffuser component, and this results in enhanced FCE.