Ice Accretion on Wires and Anti-Icing Induced by Joule Effect

Abstract

This study concerns both the formation of ice accreted around wires due to rotation from gravitational and aerodynamic forces, and the anti-icing induced by the Joule effect. The experiments have been carried out in an instrumented wind tunnel operating in natural conditions. The results show that the growth rate increases with the ice deposit thickness. Because of low airspeed and small cloud droplets, the total collection efficiency is less than 0.2. The discrepancies between the observed collection efficiencies and those predicted by Langmuir and Biodgett's theory increase with time and consequently with the ice thickness. This may be due to the complex shape of the deposit which is noncircular and presents a rough surface. These results point out the difficulties in modeling the detail of such ice profiles in this range of conditions. The air temperature plays a significant role in the rotation angle of the wire and in the ice growth rates. The surface temperature of wires is measured in order to validate the heat balance of the heated wires; this gives a proposed estimation of the current to prevent the wire from icing.