<b>Low Frequency Aerodynamic Noise from High Speed Trains</b>

Abstract

East Japan Railway Company Aerodynamic and bridge noise originate from pressure fluctuations generated by highspeed trains in open sections without tunnels. In this study, field tests using a linear microphone array were conducted in order to clarify low-frequency aerodynamic sources of noise below 100 Hz. In addition, a scale-model experiment using a launching facility for a model train was carried out to simulate actual aerodynamic noise and investigate low-noise bogie cavity designs. Through these tests, the bogie cavities under the train body were identified as being one of the major sources of aerodynamic noise. It was also found out that rounding cavity edges could be an effective measure to reduce low-frequency aerodynamic noise.

<b>Recent Studies on Aerodynamic Characteristics of Railway Vehicles</b>

“…With the above in mind, on-site tests were conducted in a non-elevated section free of bridge noise using a 28-meter-long linear microphone array to clarify sources and mechanisms of pressure variation emitted continuously from intermediate cars. Using this method, it was found that sound sources can be separated and at the same time located more accurately by averaging data from a reasonable number of trains [15]. It was also found that sources of low-frequency aerodynamic noise are concentrated at and around bogies (Fig.…”

<b>Recent Studies on Railway Aerodynamics and Noise</b>

“…Studies are underway on these sources of noise, especially to determine how the noise is generated, as well as to develop mitigation measures [20,21]. Bogies are also a primary source of low-frequency components of noise outside the audible range [22]. Accordingly, efforts are underway to develop effective mitigation measures for noise across a broad range of frequencies.…”

On the feasibility of a component-based approach to predict aerodynamic noise from high-speed train bogies

“…From measurements on Japanese trains at 320 km/h, Uda et al [10] found that bogie aerodynamic noise played a greater role than the rolling and equipment noise between 125 and 500 Hz. From scale model tests, the noise from the bogie cavity was found to be predominant for frequencies below 100 Hz (at full scale) [11,12].…”