Toshiki Kitagawa

Anechoic Wind Tunnel Tests on High-speed Train Bogie Aerodynamic Noise

ABSTRACT Aerodynamic noise becomes a significant noise source at speeds normally reached by high-speed trains. The train bogies are identified as important sources of aerodynamic noise. Due to the difficulty to assess this noise source carrying out field tests, wind tunnel tests offer many advantages. Tests were performed in the large-scale low-noise anechoic wind tunnel at Maibara, Japan, using a 1/7 scale train car and bogie model for a range of flow speeds between 50, 76, 89 and 100 m/s. The dependence of the aerodynamic noise from the bogie region on different factors has been studied for different bogie configurations and inflow conditions representing different positions of the bogie along the train. The speed dependence and the noise directivity have also been assessed. The results show the particular importance of the components exposed to the free flow, whereas those shielded within the bogie cavity are shown to radiate much less noise.

Experimental and Theoretical Studies on Impact Noise Generation due to Rail Joints

When a train passes over discontinuities on a rail, e.g. rail joints, impact noise due to the discontinuities is generated impulsively. In this paper, an attempt is made to understand the impact noise generation mechanism experimentally and theoretically. By performing static and running tests, vibratory properties of the track and wheel are investigated first. Second, on the basis of the measurements in the tests, a theoretical model to predict impact noise is developed.

Estimation of Aerodynamic Bogie Noise Through Field and Wind Tunnel Tests

A method has been developed to determine the aerodynamic noise from the bogie of a high-speed train using a two-dimensional microphone array in a wind tunnel. First, the flow velocity under the train car in the rail direction was measured in a field test. Second, the flow distribution was simulated in the wind tunnel. Third, aerodynamic noise generated by a bogie was estimated from the source distribution measured using a two-dimensional microphone array. Finally, the noise generated from the lower part of the car, which was obtained by adding the aerodynamic noise and the rolling noise estimated by the TWINS model, was compared with the result obtained from the field test. It was found that the estimated noise shows good agreement with the measurement obtained in the field test. The estimated lower part noise levels were consistent with the actual experimental measurements. This conclusion suggests that this method is appropriate to estimate aerodynamic bogie noise quantitatively. It is also shown that below 500 Hz the contribution of the aerodynamic bogie noise is more than those of the rolling and machinery noise.

Dataset for Anechoic wind tunnel tests on high-speed train bogie aerodynamic noise

Dataset supporting: Latorre Iglesias et al (2016) Anechoic wind tunnel tests on high-speed train bogie aerodynamic noise. International Journal of Rail Transportation.

Study on Effective Sound Barriers for High Speed Trains

In order to reduce noise along railway lines, sound barriers have been widely used. However, the effects of these barriers on railway noise have not been understood thoroughly. In this paper, the relative acoustical performances of a number of sound barriers in typical Shinkansen railway situations are first investigated through laboratory measurements using scale models. In the scale model studies, the effects of various types and shapes of the sound barriers on Shinkansen noise are investigated. The results show that the most effective barrier is Y-profile type. This is because the Y-profile barrier has noticeable effects on both mitigating the noise increase due to the multiple reflections of sound between the barrier and the vehicle surface and widening the shadow zone behind the barrier because of double diffractive effects. Secondly, the effect of the Y-profile barriers is examined by field tests with running Shinkansen vehicles. The results show similar trends to those in the laboratory measurements.