Eulerian Modeling of Large Droplet Physics Toward Realistic Aircraft Icing Simulation

Abstract

The supercooled large droplet problem in aircraft icing has gained more and more importance in recent years. Several experimental, numerical, and regulation efforts have been spent to bridge the knowledge gap. New phenomena have been unveiled and studied, to address and explain the peculiar features that characterize the dynamics of a supercooled large droplet water cloud. With reference to the impact behavior of a supercooled large droplet cloud onto an aircraft surface, a numerical method is presented to model the basic impact phenomena and effects at an aircraft component level. Several semi-empiricalmodels, drawnby literaturefindings, are presented and implemented in a software code to evaluate the water droplet impingement sensitivity in the supercooled large droplet regime. The computational framework is Eulerian; thus, a partial differential equation problem is solved for the water droplet field in a specified space domain. As a consequence, the new supercooled large droplet modeling does not act on the single particle when it hits the surface, but it has to be formulated as awall sink/source in thewater flowfield. To this aim, a new approach is presented, discussed, and compared with existing data. Results show that, even if physics understanding and modeling must be still carefully considered and further developed, the presented approach shows a big potential toward a more realistic prediction of supercooled large droplet icing.