• • Solid fairings reduce base-frame flow separation but increase top/mid-region noise due to flow deflection and acceleration; net noise reduction is compromised by a self-noise mechanism where unshielded insulator beam wakes impinge on the fairing side surface, generating high-amplitude pressure fluctuations—an effect rarely addressed in prior fairing research.
• • Perforated fairings provide an additional airflow pathway through small holes, reducing lateral and upward flow acceleration and suppressing wake vortex formation; leeward hole ejection pushes vortex structures downstream, creating a stable, low-fluctuation region near the fairing tail and significantly decreasing dipole source strength (pressure fluctuation).
• • Fairing installation reduces pantograph aerodynamic drag by 21.8%, a quantifiable efficiency gain for high-speed rail operations; however, flow deflection and acceleration exacerbate aerodynamic lift fluctuation of the strip, indicating a trade-off between drag reduction and aeroelastic stability that must be managed in industrial deployment.
• • Smoothing insulator beams mitigates wake impingement on the fairing, improving net noise reduction; this geometric modification is a low-cost, retrofittable measure that addresses a previously unrecognized noise source in fairing-equipped pantographs, enhancing the viability of base-frame fairings for 400 km/h train designs.