Evaluation Method for Aerodynamic Noise Generated from the Lower Part of Cars in Consideration of the Characteristics of Under-floor Flows on Shinkansen Trains

摘要

A method has been developed for predicting the aerodynamic noise from the bogie of a high-speed train using a two-dimensional microphone array in a low-noise wind tunnel. First, the flow velocity in the rail direction was measured in a field test at several points along the sleeper direction under the train car. Second, the flow distribution was reproduced precisely in a low-noise wind tunnel. Third, aerodynamic noise generated by the bogie ("aerodynamic bogie noise") was estimated from the noise source distribution measured with a two-dimensional microphone array. Finally, based on the experimental results, the noise generated from the lower part of the car (i.e. the aerodynamic noise estimated through the proposed method and the rolling and machinery noise estimated in a previous study) was compared with field test data measured near the track. The estimated lower part noise levels showed good agreement with those measured in the field test. This suggests that the proposed method is valid for the quantitative estimation of aerodynamic bogie noise. It was also shown that the contribution of the aerodynamic bogie noise is greater than the rolling and machinery noise, especially in the low-frequency region.