Film Cooling Effectiveness Measurement of Fan-Shaped Holes Manufactured Using Electrical Discharge Machining Technique

In this study, the influence of geometric factors such as hole diameter (D), length-to-diameter ratio (L/D), injection angle (α), and lateral expansion angle (β) on film cooling effectiveness of holes made using electrical discharge machining (EDM) is experimentally investigated. Nine different cooling configurations were tested on a flat plate wind tunnel at various coolant Reynolds number (Rec) and coolant-to-mainstream blowing ratio (M). The considered flat plate model incorporates engine-sized V-shaped holes. EDM reliability is assessed through a hole qualification process, while effectiveness was measured by the pressure-sensitive paint (PSP) technique. Results confirm the suitability of EDM for V-shaped hole manufacturing as long as a correct tolerance on β is prescribed. An accurate qualification of hole morphology is also recommended.