New roughness computation method and geometric accretion model for airfoil icing

Recent developments are presented in wet and dry ice accretion simulation at the Anti-Icing Materials International Laboratory in a joint project with the Italian Aerospace Research Center. An analytical model is introduced to calculate the surface roughness and the remaining, runback, and shedding liquid water mass on an airfoil surface. Three analytical formulations are used to calculate the local roughness height based on the maximum height that a bead can reach before moving and the wave height on a water film. A mass balance is used to determine the 14 remaining and runback water masses when the water state and the maximum bead height are known. The water shedding mass is determined using a simple mass model. A new method is used to build the accreted ice surface on 14 the airfoils. It uses the bisection of the angle between adjacent panels to determine ice shape. The new roughness computation method and the geometric model generate the complex ice shapes observed experimentally, and the results agree well with icing profiles obtained in wind-tunnel experiments.