Sound sources and measures of aerodynamic noise generated from bogies of Shinkansen train

When the Shinkansen train runs at a high speed about 300 km/h, the contribution ratio of the aerodynamic noise generated from bogies to the total wayside noise is as large as 30%. In general, a bogie consists of a series of elements such as wheels, main motors and gear boxes. The generation mechanism of the aerodynamic bogie noise is that high-speed airflow impinges on these devices. In this study, we used a measurement method in which the ground under the bogie was replaced with a porous plate in the wind tunnel test. This method allowed sound source identification for bogies in detail. As a result, it was clarified that sound sources of the aerodynamic noise were distributed near main motors and gear boxed. On the basis of this knowledge, we proposed several measures to reduce the aerodynamic bogie, i.e. deflectors installed before and after the bogie cavity in order to decrease the flow velocity, inward side shields which increase the acoustic screening effect, and rounding cavity corners. In this paper, the noise reduction results by these multiple reduction measures are quantitatively presented.