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Simulations of supercooled large droplet (SLD) icing environments within the NRC's Altitude Icing Wind Tunnel (AIWT) have been performed in which broad band mass distribution spectra are achieved that include a distinct pattern of liquid water content (LWC) over a range of droplet sizes (i.e., bi-modal distribution). The mass distribution is achieved through modification of the existing spray system of the AIWT to allow two spray profiles with differing LWC and median volumetric diameter (MVD) to be simultaneously injected into the flow. Results of spray profile distributions measured in the test section have demonstrated that freezing drizzle conditions, where MVD is either less than or greater than 40 μm, can be achieved.

This paper discusses, illustrates and validates a novel modeling approach capable of predicting two-dimensional ice accretion on airfoils. The external flow field around a NACA 0012 airfoil is computed using a potential approach with a panel code. In addition to calculating droplet trajectories and impingement locations on the airfoil, the model tracks the behaviour and motion of individual fluid elements on the icing surface. While the envelope of possible behaviour and motion of the elements is constrained by the macroscopic environmental and flight conditions, an intrinsic stochastic variability is present in the model, even under constant external conditions. A partial validation of the model has been successfully accomplished.