External radiative heat transfer corrections for film-cooled turbine blades in hot environments

With the increasing temperature ahead of the aero-engine turbines and the rapid development of cooling technologies, thermal radiation has emerged as a pivotal consideration in the turbine blade design refinement. The existing engineering empirical algorithms, which rely on cooling margins to account for radiation effects, are inadequate for meeting the demanding cooling requirements of turbine blades in intense radiation fields. Therefore, a radiation-adapted temperature correction approach for accurate film-cooling predictions in intense radiation fields was developed in this study. Firstly, the radiative Nusselt numbers (Nu) for the outer surface of the film cooling structure were established, which can correct the existing convective Nu to the total Nu with radiation effects. Subsequently, the radiative correction method for the temperature characteristics by modifying the external heat transfer boundary conditions was introduced. The method proposed can reduce the maximum absolute error in temperature calculations from 100 K before correction to 25 K, when the radiation number is 188.53. The proposed radiation-adapted Nusselt correlation improves film-cooling design by delivering accurate heat transfer coefficients for reliable temperature field predictions in cooled structures. In addition, the correction method can improve the temperature computational efficiency compared to directly solving the radiative transfer equation.