Comparative Investigation on Effect of Droplet Deformation Models on SLD Icing

It is well known that SLD (Supercooled Large Droplets) icing is very dangerous because it is more unpredictable than general icing caused by smaller droplets. In SLD conditions, a droplet deforms largely. Vargas et al. (2011) performed the experiments about the droplet deformation and they confirmed that the droplet deforms to an oblate spheroid, as the droplet approaches the leading edge of an airfoil. Therefore, the assumption that a droplet behaves as a sphere might be no longer valid. There are many models to predict the droplet deformation in which the deformation is described with the change of drag coefficient. For example, Hospers (2013) summarized the linear relations between the Reynolds number and the drag coefficient. Wiegand (1987) developed a model which uses a quasi-steady normal mode analysis of droplet deformation. However, the effect of the droplet deformation models on SLD icing simulations has not been completely clarified yet. Therefore, in the present study, the authors investigated the effect of the droplet deformation models on SLD icing simulations. The authors used a NACA0012 airfoil, and compared the numerical results with the NASA experiments. It was confirmed that the ice shape, the droplet impinging limit and the icing limit are influenced by the model of the drag coefficient.