Numerical Simulation of SLD Ice Accretions

In this study, computational methods are presented that compute ice accretion on multiple-element airfoils in specified icing conditions. The “Droplerian” numerical simulation method used is based on an Eulerian method for predicting droplet trajectories and the resulting droplet catching efficiency on the surface of the configuration. Flow field and droplet catching efficiency form input for Messinger's model for ice accretion. The droplet trajectory method has been constructed such that the solution of any flow-field simulation (e.g., potential-flow, Euler equations) can be used as input for the finite-volume solution method. On an unstructured grid the spatial distribution of droplet loading and droplet velocity are obtained. From these quantities the droplet catching efficiency is derived. Of special interest in this study are the Supercooled Large Droplets (SLD). The simulation of SLD requires a specific splashing model.

For a single-element airfoil a good agreement is found with the Lagrangian method 2DFOIL-ICE and with experimental results. The comparison of the catching efficiency predicted by both simulation methods is good for the smaller droplets. For larger (SLD) droplets the splashing and rebound models are a significant improvement to the catching efficiency results when compared with the experimental results.