A Comprehensive Numerical Model for Numerical Simulation of Ice Accretion and Electro-Thermal Ice Protection System in Anti-icing and De-icing Mode, with an Ice Shedding Analysis

Abstract

<div class="section abstract"><div class="htmlview paragraph">This work presents a comprehensive numerical model for ice accretion and Ice Protection System (IPS) simulation over a 2D component, such as an airfoil. The model is based on the Myers model for ice accretion and extended to include the possibility of a heated substratum. Six different icing conditions that can occur during in-flight ice accretion with an Electro-Thermal Ice Protection System (ETIPS) activated are identified. Each condition presents one or more layers with a different water phase. Depending on the heat fluxes, there could be only liquid water, ice, or a combination of both on the substratum. The possible layers are the ice layer on the substratum, the running liquid film over ice or substratum, and the static liquid film between ice and substratum caused by ice melting. The last layer, which is always present, is the substratum. The physical model that describes the evolution of these layers is based on the Stefan problem. For each layer, one heat equation is solved. At the ice-water interface, a Stefan condition governs the phase transition. Lastly, mass conservation is imposed. Numerical simulations are compared to reference results, both experimental measurements and numerical simulations for both ice accretion and ETIPS operating in anti-icing and de-icing mode, showing good agreement. A posterior ice shedding analysis is then performed, taking into account the IPS in both anti-icing and de-icing operation modes. The stresses internal to the ice shapes when subjected to the aerodynamic loads are compared with the mechanical properties of ice such as the tensile and adhesion strength. The results show that the de-icing mode is more efficient in causing shedding due to the decrease in adhesion surface and the presence of the under-ice liquid film that tends to break the ice shape.</div></div>