Numerical Investigation of Ionic Wind-Flow Characteristics in Direct-Current Transmission Conductors With Different Cross- Sectional Geometries

Abstract

Corona effect is a critical factor in the design and construction of ultrahigh-voltage (UHV) transmission lines, since it can cause ionic wind, which induces destructive instability, such as conductor vibration and rotation. Here, we develop a 2-D unipolar ion discharge model by using electrohydrodynamic (EHD) methods coupled with Navier-Stokes (N-S) equations. The effects of conductor cross-sectional geometry and voltage levels on the distribution of electric field, characteristics of ionic wind, and distribution of EHD force during the corona discharge have been studied. It is shown that both the cross-sectional geometry and voltage level have significant influence on the aerodynamic characteristics of the conductor. A higher corona inception field strength can be produced when the conductor geometry is closer to a cylindrical shape. As the number of strands in the conductor is increased, the cross-sectional geometries become more complex, leading to greater electric field distortion, which assists the ionic wind effect and maximum composite velocity. Higher voltage levels inhibit the ionic wind speed, resulting in a reduced maximum composite velocity. Moreover, the increases in the number of conductor strands and voltage levels can enhance the EHD force, inducing the fluctuations in ionic wind velocity around the conductors. Our results provide insights into ionic wind generation from corona discharges in transmission lines and offer theoretical guidance for mitigating the corona-induced vibrations.