Investigation of noise sources in high-speed trains

Abstract

In this paper, the quantification of the external noise sources in high-speed trains is discussed. A thorough understanding of the underlying causes of noise generation in high-speed trains is needed to develop effective noise control measures. However, because high-speed trains produce a complex array of sounds, it is very difficult to determine each individual source of noise. In this study, the delay-and-sum beamforming method, which uses microphone arrays, was used to separate the noise sources and analyze the sound characteristics of high-speed trains. A new microphone array with 96 microphones was designed to measure the noise produced by high-speed trains. Performance verification tests were conducted to ensure the reliability of the results obtained from the array. Then, the system was used to measure the sounds produced by Korean high-speed trains traveling at speeds between 150 and 300 km/h. Sound maps were then produced using the beamforming technique. The study determined that the majority of the noise produced by the highspeed trains originated from the front nose, bogie, pantograph and inter-coach spacing. Finally, the beampower spectra of the aerodynamic noise sources originating in the front nose, pantograph and inter-coach spacing were deduced from frequency conversion. From these results, the aerodynamic noise characteristics of the major sources of noise in highspeed trains were determined.

Recent developments in the prediction and control of aerodynamic noise from high-speed trains

“…Martens et al [21] used a spiral array with a diameter of 4 m in order to improve the resolution at low frequencies but they also used a spiral array with 2 m diameter and smaller distance between microphones to operate up to 5 kHz. The array configuration used by Noh et al [24] was radial and irregular with nested arrays using 96 microphones and obtaining good resolution in the range between 200 and 8000 Hz.…”

“…However, to prevent spatial aliasing the distance between microphones should be less than half the acoustic wavelength which limits the upper frequency that can be resolved [15]. Examples of measurements using microphone arrays during the passage of different high-speed trains are given in References [17][18][19][20][21][22][23][24]. Different configurations of microphone array can be used in order to optimise its performance depending on the situation.…”

Effect of cavity flow control on high-speed train pantograph and roof aerodynamic noise

“…Several experimental and numerical studies have been performed to study the flow and acoustic features of the pantograph recess [12,13]. Noh et al [12] carried out noise tests for a full-scale Korean high-speed train (KTX). They found that the noise from the recess was at similar level to that from the pantograph at a speed of 300 km/h.…”

Study on generation mechanism and source of aerodynamic noise of high-speed train

“…Meanwhile, the noise produced by high-speed trains is becoming increasingly significant and it has a great influence on surrounding environment and ride comfort. According to some studies [1][2], the noise can be mainly divided into rolling noise, traction noise and aerodynamic noise. Moreover, the aerodynamic noise is strongly dependent on the train speed U, being approximately proportional to U 6 -U 8 .…”