高速鉄道の曲線部で発生する高周波音の現象解明

抄録

Studies to develop understandings of rolling noise, which has great influence on wayside noise in the frequency range 250 Hz to 4k Hz, have been carried out widely by measurements and theoretical models. In some studies, when a train runs on a gentle curved track, wheel/rail noise is greater by more than 5 dB. And, it is found that this is closely related to noise at higher frequencies above 10 kHz (referred to as high-frequency noise), which is different from squeal noise, e.g. mechanism due to contact between inside rail and wheel tread. Such high-frequency noise is observed on both low-speed (160 km/h at most) and high-speed railway lines. Previous studies in Japan found that, on a low-speed railway line, the dominant sources of high-frequency noise are the wheels on the outside rail. But, on a high-speed railway line, the characteristics of the high-frequency noise generated in the curved section remained unclear. In this paper, the contribution of the high-frequency noise to wayside noise on a high-speed railway line is investigated in field tests and static experiments, the latter involving shaker excitation. It is found that, during the passage of a train, the wheels on the outside rail are the dominant noise source. And, the wheel noise is found to depend on the train speed. Furthermore, source localization related to the wheel noise above 10 kHz is carried out through field tests with a directional microphone. These results show that the wheel noise above 10 kHz is mainly generated by the outside leading wheel of each bogie.