Bio-inspired helical pantograph arms for aerodynamic noise suppression in high-speed trains.

The pantograph is a major aerodynamic-noise source on high-speed trains, where vortices around pantograph arms and the panhead dominate sound generation. Inspired by seal whiskers and butterfly antennae, this study proposes two bio-inspired helical arm designs-twisted and coiled-implemented on the pantograph. Numerical simulations employ improved delayed detached Eddy simulation (IDDES), the Ffowcs Williams-Hawkings (FW-H) acoustic analogy, and the acoustic perturbation equation (APE) to assess three pantograph configurations: cylindrical, twisted, and coiled. The twisted configuration yields the largest gains, reducing root-mean-square lift fluctuations by 68.9% and lowering mean drag (the coiled design also reduces drag), thereby improving stability and flow quality. Acoustically, the twisted pantograph cuts maximum far-field sound pressure by 4.2 dBA and suppresses near-field noise near the panhead by up to 5.4 dBA, with effectiveness superior to that of the coiled design. These results indicate that biomimetic arm shaping can produce quieter, more efficient pantograph systems.