Numerical investigations of secondary cooling on endwall with various cutback slot configurations

The present study numerically investigated the secondary effect of trailing edge film cooling on the downstream endwall surface with various cutback slot configurations. The factors of mass flow rate ratio (MFR = 1–4 %), compound angle (α = 15°, 30° and 45°), and trailing edge cutback position (pressure-side cutback (PC) and central cutback (CC)) are considered. The distributions of film cooling effectiveness (η) and Nusselt number (Nu) are both presented in this study. The findings reveal a significant impact of MFR and compound angle on the spanwise momentum of the coolant, which alters the endwall film cooling effectiveness and heat transfer. An increase in MFR consistently leads to a notable enhancement of endwall film cooling effectiveness and heat transfer. An increase in the compound angle enhances endwall heat transfer, while its influence on the endwall film cooling effectiveness is intricate and varies between the upstream and downstream endwall. Ultimately, there exists an optimal combination of MFR and compound angle that minimizes net heat flux ratio (NHFR). Furthermore, CC configurations exhibit superior secondary cooling on endwall and lower pressure loss compared to PC configurations, attributed to the reduced impact of the mainstream on the coolant flowing from CC. The data are helpful for a deeper insight into the secondary effect of film cooling and may provide a reference for future research.