Heat transfer characteristics of turbine blade film cooling with different curvatures in high-temperature radiative environments

As turbine inlet temperatures in aero-engines rise, thermal radiation effects on turbine blades cooling become increasingly critical. Complex geometric structures, including concave and convex surfaces, can modify heat transfer and radiation transfer paths compared to the mainly used film-cooled plate model. This study employs a wideband model for H₂O/CO₂ absorption coefficients with high volume fractions under high-temperature, high-pressure conditions. The discrete ordinates and turbulence coupled models are employed to investigate the convection-radiation heat transfer laws of three characteristic surface curvatures: concave, convex, and flat. The results show that along the flow direction, the spanwise-averaged cooling effectiveness decreases by approximately 0.04–0.1 (concave), 0.06–0.11 (flat), and 0.07–0.12 (convex) under gas and walls radiation. The radiation-induced reduction in cooling effectiveness diminishes downstream, reaching its minimum near the outlet and maximum adjacent to the film hole. Additionally, radiation decreases the average heat transfer coefficient (h_f /h₀) by about 0.1 and expands the downstream regions with h_f /h₀ < 1, as it diminishes mixing-induced heat flux between coolant and mainstream. Regarding the net heat flux reduction (NHFR) performance, radiation remains detrimental. Along the flow direction, the radiation-induced NHFR reduction diminishes progressively downstream. The radiation reduces spanwise-averaged NHFR by 0.05–0.12 (concave), 0.1–0.15 (flat), and 0.1–0.16 (convex).