Effects of Ice Surface and Ice Shape on Aerodynamic Characteristics of Crescent-Shaped Iced Conductors

Abstract

In current galloping studies, the shape and surface of ice accretion are usually simplified to the regular and smooth properties, although they have the probability of irregularity and roughness in real conditions. To study the effect of these two factors on galloping stability, high-frequency force balance (HFFB) wind tunnel tests were conducted to obtain the aerodynamic characteristics of crescent-shaped iced conductor models with different ice surface roughness and ice shape. Furthermore, based on the Den Hartog and Nigol galloping mechanisms, the differences of galloping stability judgment are analyzed. Finally, a finite-element numerical simulation is also conducted to compare the galloping properties of iced conductors with rough and smooth surfaces. The results show that ideal crescent-shaped iced conductors with smooth ice surfaces are more prone to galloping compared with the rough ice surface condition, which is also verified by the results of the finite-element numerical simulation. Additionally, irregularities of the ice shape will result in a decrease of Den Hartog and Nigol coefficients in the negative value range, which means it is more likely to lead to the galloping phenomenon.