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Noise generated from Shinkansen trains mainly consists of wheel/rail noise, bridge noise and aerodynamic noise. Generally rolling and bridge noises are proportional to the second to third power of the train speed, whereas the aerodynamic noise is proportional to the 6th power of the train speed. Then, the aerodynamic noise becomes dominant at above 300km/h. In the past studies, the main sources of the aerodynamic noise are the pantographs and bogies. In particular, the contribution of the aerodynamic bogie noise to wayside noise is greater than the pantograph noise. Therefore, in order to reduce the wayside noise properly, it is necessary to make a better understanding of the aerodynamic bogie noise. In this study, a new method is proposed to estimate the aerodynamic bogie noise precisely in wind tunnel test; a part of the ground under a bogie is replaced by a porous plate through which the sound wave propagates but blocks off the air flow, and a microphone array is installed under the porous plate toward the bogie. This measurement method made it possible to determine the sound source of the bogie in detail. As a practical demonstration, this method is used to verify a simple noise reduction technique for bogies and one of the noise reduction mechanisms are clarified properly.
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