A model for in-flight ice accretion based on the exact solution of the unsteady Stefan problem

A modification to the Myers model is proposed to study the inuence of the unsteadiness of the temperature profile within the ice layer on in-flight ice accretion. The new model is based on the exact solution of the unsteady Stefan problem. The model was implemented in the ice accretion software PoliMIce developed at Politecnico diMilano to perform numerical simulations of in-flight ice accretion over two-dimensional airfoils in both rime and glaze ice conditions. The CFD open-source software OpenFOAM was used for computing the aerodynamic solution and for reconstructing the water droplet trajectories. Preliminary results indicate that the modifications introduced to the original Myers model improve significantly the accuracy of the prediction of ice shapes, in particular of the two-horn configurations in the considered test cases. Modifications include an unsteady description of the heat diffusion problem within the ice layer and a different approach for the computation of convective heat fluxes. In particular, the local value of the air temperature outside the boundary layer is adopted, instead of the constant, free-stream value considered in Myers model.