Numerical Study on the 3D Inclination Angle of Film Cooling Under Non-adiabatic Conditions

As the gas temperature increasing, intricate cooling structures must be applied to the turbine blade, where film cooling is a major one. To continuously improve the film cooling efficiency, adopting a reasonable assessment method is particularly important. Adiabatic film cooling effectiveness η is a widely employed one while neglecting heat transfer in the solid domain. Aiming at its limitations in engineering, film cooling under non-adiabatic conditions were analyzed. The phenomenon of heat flux backflow in the solid domain was revealed, then a dimensionless design indicator: film absolute coverage coefficient—ζ, also a novel assessment method based on it was proposed. Furthermore, flow and heat transfer numerical analyzing of film cooling with different 3D inclination angles—γ and β were carried out employing these methods. The results exhibited the phenomenon of gas overheating and the notch of film absolute coverage area, which is usually ignored in adiabatic analysis. In addition, the effectiveness of the 3D inclination film cooling and the influence of angle γ and β was analyzed by the intermediate variables n and f extracted from the film absolute coverage area. The novel methods achieved in solving a typical film cooling issue, which predicted their advantages of turbine blade design under actual engine operating conditions.