Analysis of flow velocity fluctuation around a train model running in a tunnel using restored waveforms

Abstract

A pantograph receives aerodynamic force while a train is traveling. As the aerodynamic force increases in proportion to the square of the flow velocity relative to the pantograph, its influence on the pantograph becomes apparent, especially for high-speed trains. When a high-speed train runs in a tunnel, the flow velocity relative to the pantograph is faster than that in an open section. In this study, we measured the flow velocity around a train model running in a tunnel using a rake of total-pressure tubes mounted on the train model. The measured waveforms were distorted owing to the influence of the frequency characteristics of the measurement system. Therefore, we developed a restoration method and applied it to the measured waveforms to obtain the restored waveforms of the flow velocity. With the restored waveforms, we obtained several statistical values, such as the average flow velocity and standard deviation of the fluctuating flow velocity around the train model. Furthermore, we proposed a method for predicting the flow velocity around the train model, including fluctuating components in a frequency range of a pantograph contact performance. The proposed method can predict the flow velocity at the panhead of a pantograph by considering the average flow velocity profile and turbulence component profile in the tunnel cross section, which could not be taken into account so far.

Keywords

• flow velocity measurement
• train
• tunnel
• restoration filter
• fluctuating flow velocity