Impact of radiative heat flux on turbine blade heat transfer in high temperature environments

The efficient cooling technology used in first-stage turbine vanes results in a large temperature difference between the blade wall and high-temperature gas. The resulting thermal radiation cannot be neglected. However, in experimental environments, it is impossible to accurately assess the effects of radiation. In this study, a novel, simplified version of an existing experimental method is proposed, to distinguish the radiation from the total heat flux; it uses blade wall-temperature measurements and ternary nonlinear regression. The results show that when the mainstream temperature is 1000–1300 K and the cold air temperature is 550–750 K (T_∞/T_cold > 2.5), the radiative heat flux accounts for 15–20% of the total heat flux (when the gas composition is pure air). In real working conditions (T_∞/T_cold ≈ 2.2), the radiative heat flux cooled without an air film accounts for 11.96–14.4% of the total heat flux. When the gas includes radiation-participating media (e.g., CO₂ and H₂O), the radiative heat flux accounts for 21.4–22.72% of the total heat flux. The effects of radiation cannot be neglected in studies considering the heat transfer of turbine blades. In addition, the radiation correction factor is defined to comprehensively account for the effects of radiation. Under real conditions (T_∞/T_cold ≈ 2.2), the radiation correction factor is 1.275. Finally, the simplified approach is validated using numerical calculations.