In order to reduce the pantograph noise that greatly contributes to overall noise, we have developed two types of low-noise pantograph. Further noise reduction was realized by the effects of attenuation of the pantograph noise insulation plate and by using only one pantograph per trainset. A multi-segment slider was also developed to increase the performance of following the overhead contact wire, which is imperative when running with only one pantograph per trainset. These countermeasures for pantograph noise have been installed on FASTECH 360 (high-speed test trains of East Japan Railway Company). The results measured by use of a microphone array show that the pantograph peak noise level is reduced by more than 2 dB compared to that of the series E2 trains now in operation.

To investigate the mechanism of noise generation by a train-car gap, which is one of a major source of noise in Shinkansen trains, experiments were carried out in a wind tunnel using a 1/5-scale model train. We measured velocity profiles of the boundary layer that approaches the gap and confirmed that the boundary layer is turbulent. We also measured the power spectrum of noise and surface pressure fluctuations around the train-car gap. Peak noise and broadband noise were observed. It is found that strong peak noise is generated when the vortex shedding frequency corresponds to the acoustic resonance frequency determined by the geometrical shape of the gap, and that broadband noise is generated at the downstream edge of the gap where vortexes collide. It is estimated that the convection velocity of the vortices in the gap is approximately 45% of the uniform flow velocity.

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