EFFECT OF FILM HOLE CONFIGURATION ON THE IMPINGEMENT-FILM COMPOSITE COOLING PERFORMANCE OF A SIMULATED TURBINE BLADE LEADING EDGE

Eight film hole configurations were implemented on a simulated turbine blade leading edge to serve as the shower-head. Both adiabatic and conjugate heat transfer analyses were conducted. The effect of film hole configuration on flow resistance, heat transfer characteristics, film coverage, and composite cooling performance of the leading edge were all investigated. Additionally, the influence of coolant mass flowrate across a wide range was also considered. The results indicate that all expansion holes effectively increased the discharge coefficient, especially at relatively higher coolant mass flowrate. The amplified hole and double-jet hole also reduced the flow resistance under high coolant mass flowrates, but caused severe gas ingestion at low mass flowrates. Furthermore, impingement cooling demonstrated continuous improvement in heat transfer intensity with increasing coolant mass flowrate, while the effect of expansion holes on it was nearly negligible. Moreover, the composite cooling performance of expansion holes was highly correlated with both forward and lateral expansion angles, which played a more critical role than hole shape designs in determining the cooling performance. In comparison to conventional showerhead designs, the two novel holes exhibited significantly improved composite cooling performance, especially the effusion hole. However, it should be noted that the incorporation of effusion hole also resulted in serious pressure loss of coolant.