Aerodynamic Characteristics and Galloping Stability of Iced Contact Lines in High-speed Railways: A Computational Fluid Dynamics and Experimental Study

The current collection reliability in high-speed railways is threatened by flow-induced oscillations of contact lines that have accumulated ice. A substantial body of literature on transmission line galloping has repeatedly documented the influence of ice-covered thickness and airflow velocity, while the specific aerodynamic characteristics of railway contact lines under realistic icing geometries remain largely unexplored. To address this issue, this research employs a comprehensive approach, combining two-dimensional computational fluid dynamics (CFD) with low-speed wind tunnel testing, to evaluate the aerodynamic performance and galloping stability of crescent and fan-shaped ice-covered contact lines. Aerodynamic coefficients were obtained for different ice thicknesses, wind speeds, and ice shapes, and galloping instability was evaluated based on the Den Hartog and Nigol criteria. The results indicate that crescent-shaped ice significantly amplified torsional instability, with the critical negative-slope region of the lift–drag coefficient curve increased by 23.7% compared with fan-shaped ice. In contrast, fan-shaped ice primarily promoted vertical galloping, leading to an 18.5% increase in the critical instability region relative to crescent ice. These findings provide new insights into the distinct instability mechanisms of iced railway contact lines and underscore the importance of mitigation strategies tailored to specific shapes of ice for high-speed railway systems.