Characteristics of aerodynamic noise from the inter-coach spacing of a high-speed train

Abstract

As the speed of high speed trains increases, the aerodynamic noise tends to dominate all other noise sources. Several measurements for high-speed trains in Korea confirmed that aerodynamically generated noise is significant when the train speed exceeds 250km/h. This phenomenon becomes prominent in the low frequency range below 200Hz, especially, when the train passes tunnels. It has a baneful influence upon interior noise because the sound insulation characteristic of the car-body structure is very weak in this low-frequency range. In this paper, experiments were performed in order to investigate the characteristics of aerodynamic noise sources generated from the inter-coach spacing of a high-speed train. It has been found that the low frequency noise is strongly dependent on the size of the inter-coach spacing that increases the turbulent intensity of the flow along the train surface and also inside the cavity. These pressure fluctuations excite the train structure which in turn radiates noise inside the passenger cabin. Measurements of both the inside and outside of the cabin are carried out to investigate the characteristics of the noise. Also performed is an array measurement to locate different noise sources from the high-speed train. Finally efforts have been made to reduce the interior noise level by varying the width of mud-flaps, rubber curtains used to prevent inter-coach components from contamination, and the results show significant decrease in the interior noise for the optimized width of mud-flaps.