要約

The heated airfoil operating under icing conditions has some important characteristics that differentiates the problem from the case of adiabatic airfoil subjected to ice growth. In presence of thermal ice protection, the hypothesis of flow over isothermal surfaces, which is assumed by most classic icing codes, may not represent the operation satisfactorily. The present paper implemented successfully two modeling strategies that considers streamwise surface temperature variations in thermal boundary-layer evaluation by integral procedure: 1) solution of the approximated enthalpy thickness integral equation assuming flow over a non-isothermal surface; 2) application of superposition principle to thermal boundary-layer solutions to represent the effects of flow over a surface with non-uniform temperature distribution. The numerical results were compared with isothermal model results as well as the experimental results of flat plate in a wind tunnel and two NACA aifoils, the 0012 and the 65₂-0016, operating in icing tunnel under clear air and icing conditions. The streamwise surface temperature gradient, water evaporation rate variation and the presence of laminar-turbulent transition, when occurring within the protected area, are effects that are represented adequately by the mathematical models.