Physics of aircraft icing: A predictive challenge

After giving a brief overview of the current industrial and regulatory interests in aircraft icing, this paper outlines some of the main challenges in understanding the physics involved in the various forms of icing mechanisms, either from high altitude ice crystals or from supercooled large droplets (SLD). Whereas the main concern of ice particles is associated with ingestion into engines and subsequent power losses or turbine damage, the danger with supercooled large droplets is related to airframe icing and loss of lift or increase in drag. The central issues addressed are: particle/drop trajectories, particle/drop impact, and ice accretion. In predicting particle/drop trajectories the non-sphericity must be accounted for, both hydrodynamically and for the heat transfer in the case of ice crystals. In terms of impact modelling the presence of a liquid film either on the ice crystal or on the target surface presents a particular challenge, especially when estimating whether the particle adheres to the surface or escape. Finally, the accretion of ice presents numerous challenges, both hydrodynamically as well as thermodynamically. Some particular examples will be reported to illustrate difficulties and challenges encountered. © 2015 Begell House, Inc.