Aerodynamic forces on iced cylinder for dry ice accretion - A numerical study

Within this paper the ISO 12494 assumption of standard of slowly rotating reference collector under ice accretion has been tested. This concept, introduced by (Makkonen, 1984), suggests that the power line cables, which are the basis of the "reference collector" in the ISO framework, are slowly rotating under ice load, due to limited torsional stiffness. For this purpose, several Computational Fluid Dynamics (CFD) simulations of the atmospheric ice accretion and transient airflow conditions over iced cylinder at different angles of attack were performed. In order to ascertain the similarity, several parameters were chosen, namely, drag, lift and moment coefficients, pressure and viscous force. The results suggest that the benchmark cases of rotating and uniced cylinder have "similar" aerodynamic loads when compared with the "averaged" results at different angles of attack (AoA), namely, the values of total pressure and viscous force. However, on individual and instantaneous basis the difference in the airflow regime between AoA cases and the benchmark cases can be noticeable. The results from the ice accretion simulation suggest that at long term the gravity force will be the dominating one, with rotating cylinder being a good approximation to the "averaged" angle of attack cases for the ice accretion.