Transport processes in a wet granular ice layer: Model for ice accretion and shedding

Abstract

Aircraft icing due to ice crystal impact occurs in the relatively hot areas near the engines, where the ice particles partially melt. Ice crystal accretion in the presence of a liquid water fraction leads to the creation of a wet granular ice layer. The present study addresses the transport processes in this granular ice layer in order to describe theoretically the ice accretion phenomenon and to predict the instant of ice layer shedding. Among these transport phenomena are heat transport in the granular solid ice region, water region and gas area, ice granule melting and solidification, and liquid water imbibition. Within the scope of this work, a theoretical model describing these transport phenomena in a granular media is developed. The equations for the effective transport are formulated and solved numerically using a computational code based on a Finite-Volume method. The model is applied to the description of ice crystal accretion on warm aircraft components and the results are compared with available experimental data. The theoretical predictions agree well with the experimentally observed icing and shedding behavior by describing the composition and heat and mass transport within the ice layer.