New Roughness-Induced Transition Model for Simulating Ice Accretion on Airfoils

Appropriately modeling surface roughness is crucial for predicting in-flight icing due to its influence on convective heat transfer. Most prevalent numerical simulations to this end rely on empirical correlations, where surface roughness is assigned a constant value. This limits the accurate computation of turbulent transitions, leading to a discrepancy between the experimental and the simulated shapes of ice. To improve shape prediction, this Paper proposes an approach to simulate the roughness distribution and its effect on the transition. The roughness distribution is determined analytically for water beads on the surface, and the roughness amplification parameter is explicitly computed using the turbulence model. The results of simulations of a rough plate and airfoil with leading edge roughness yielded good agreement with experimental data for transition-related behavior. Then, the convective heat transfer coefficient on iced surface and ice shape was predicted and compared with the result of the fully turbulent model and experiments. The proposed method showed better prediction of the ice shape, especially on the suction side of the airfoil for glazed and mixed ice.