Quasi-Steady Simulations of Glaze Ice Accretion in Turbulent Flow on Aircraft Wings in Supercooled Clouds in the Large Droplet Regime

In an attempt to avoid the use of a computationally intensive unsteady simulation while still providing a highly accurate solution, a quasi-steady approach has been adopted to study atmospheric ice accretion in the supercooled large droplet regime in turbulent flow. Quasi-steady solutions can be highly accurate if a sufficiently small time step is selected to advance the solution in time. In this work, we have attempted to find the minimum time interval necessary to adequately simulate the icing process on an aircraft wing in turbulent flow. A mesh morphing scheme has been used which is based on adopting a node displacement in the computations to account for the moving boundaries that are caused by ice buildup. Re-meshing is required in maintaining the grid density of high curvature zones for full quasi-steady simulations. Employing a mesh morphing scheme makes the multi-shot simulations computationally more efficient relative to the full unsteady solution. After successfully modeling glaze icing over an aircraft wing, the effects of supercooled large droplets impacting the wing surface are examined in terms of the behavior of several key variables such as the droplet collection efficiency, water film thickness, and heat transfer rate. In monitoring the droplet collection efficiency and convective heat fluxes at each shot, the approach adopted here was found to be effective in successively reproducing the curvature of the glaze ice horn, which is more discernible for large droplets ($d=50,100,200\hspace{0.2em}\mu m$). Results of the numerical simulations reveal that irregularities in the ice structure, which can be observed either in the horn region or on the bottom surface of the wing, are more influenced by droplet size than by the liquid water content, and become more severe at larger free stream velocities.