A Refined In-Flight Icing Model and its Numerical Implementation

A refined in-flight icing model is proposed whose primary focus lies on an improved prediction of the runback dynamics. The most significant capabilities/properties of the model are:

• Incorporation of surface tension and wetting effects in the runback model
• Fully transient treatment of the ice accretion/depletion process and the runback flow
• Treatment of unsteady heat transfer in the runback layer, the accreted ice layer and the underlying substrate as well as phase transitions solid/liquid in the ice layer
• Strict mass- and enthalpy-conservative growth/depletion of the ice layer (this is achieved by a specially designed mesh deformation algorithm)

An essential part of the paper is devoted to the treatment of surface tension and wetting effects: These effects result from disjoining pressure contributions to the pressure terms in the runback continuity equation, i.e., these effects are inherent properties of the simulated runback dynamics. In particular, phenomena such as film rupture, bead formation and bead coalescence naturally appear in the computed runback flow, and also contact angle hysteresis effects can be simulated with the current wetting model. Besides the treatment of wetting effects the numerical methods utilized for the time-integration of the coupled system consisting of the runback continuity equation and the energy equations of the runback layer, the ice layer and the underlying substrate are described in the paper. Finally, two test cases which were simulated with the aid of a 2D-implementation of the current model are discussed.