Flow Field Characteristics and Aerodynamic Mechanisms of Bundled Conductors Considering Real Cross-Section Effects in Sustained Wind Regions

The region of Xilingol League in Inner Mongolia exhibits typical sustained wind characteristics. To reveal the typical flow field behavior of transmission line conductors in sustained wind regions, this study takes the Xilingol League area as the research subject. First, based on regional meteorological data and investigations of transmission line, the characteristics of the sustained wind and typical conductor are analyzed. Two representative conductors, JLB40-120 and JL/G1A-400/35, are selected for the study. On this basis, two-dimensional numerical models of an actual stranded conductor cross-section and an equivalent smooth circular cylinder are established to conduct a comparative analysis of flow separation, wake evolution, Kármán vortex street formation, and pressure distribution characteristics for both a single conductor and a twin-bundled conductor under sustained wind. Furthermore, a three-dimensional flow field model is constructed to investigate the characteristics of streamline around the conductor and the spatial distribution of surface pressure. The results indicate that, compared to a single conductor structure, the twin-bundled conductor structure exhibits more significant wake interference between sub-conductors, resulting in more complex wake structures and pressure distributions. Compared with the equivalent smooth circular cylinder, the actual stranded conductor cross-section, due to its surface geometric irregularities and structural details, is more prone to inducing early boundary layer separation, leading to more complex wake evolution and asymmetric vortex shedding. The three-dimensional model further reveals that the flow around the conductor exhibits pronounced spatial characteristics, with both the wake vortex structures and surface pressure distribution showing non-uniform three-dimensional features. The results provide a reference for the analysis of wind-induced vibration mechanisms of transmission lines and the optimization of related structural designs under sustained wind conditions.