High-speed Train Noise Research Articles

Interior noise prediction of inter-coach space of high-speed maglev trains based on wavenumber decomposition on aerodynamic excitation

Current research on noise and vibration control of high-speed maglev trains pays more attention to far-field noise, while the level of interior noise has a direct impact on the ride comfort and should be placed equal weight on. In this paper, inter-coach space, one of the main pressure fluctuation sources of a specific type of high-speed maglev train with a design speed of 600 km·h−1, is taken as the research object. The turbulent and acoustic components of wall pressure fluctuations (WPF) are separated based on a wavenumber-frequency analysis approach, and then each component is applied as different forms of source input to the vibroacoustic model, namely, finite element method-boundary element method (FEM-BEM) and statistical energy analysis (SEA) for low- and high-frequency ranges respectively, to investigate the contribution of both components to interior acoustic cavity in all frequency range. It can be seen quantitatively from the results that the amplitude of turbulent component is generally much higher than that of the acoustic one, but it can be vice versa when it comes to the interior response. The conclusion drawn in this paper are able to provide guidance for future researches on more targeted interior noise control of high-speed maglev trains.

Prediction and analysis of flow-induced noise of a real-size high-speed train using compressible Large Eddy Simulation and vortex sound source

As technology advances, high-speed trains have become faster, and the aerodynamic noise generated by their exterior flow fields has become a critical consideration in the design process. Accurately predicting the flow-induced noise of high-speed trains requires high-resolution sound source generation in the near-field and noise propagation in the acoustic field without numerical dissipation. This necessitates the appropriate design of the grids from the point of aerodynamic noise generation and propagation in association with the length scales of the relevant components of an actual train. To address this challenge, this research study employs a three-dimensional compressible Large Eddy Simulation (LES) technique with high-resolution grids to simultaneously calculate the external flow and acoustic fields of a real-size high-speed train consisting of five cars running in open field. Further analysis is carried out to evaluate the contribution of major components, including the cap, pantograph, bogie, intercoach, and HVAC cover, which are known to be significant contributors to high-speed train flow noise. The study also employs the vortex sound source to analyze the generation mechanism of flow-induced noise for each component, providing insights for reducing aerodynamic noise.

Masking effect of water sound on road and rail traffic noises in office soundscape

This study represents a laboratory experiment focusing on the effect of water sound on masking traffic noises in an office soundscape. Subjective evaluations and physiological responses of thirty-two participants exposed to the combination of water sound and traffic noises were measured. Silence and pure traffic noises were used as the reference conditions. Significant masking effects of water sound were observed on both the subjective evaluation of the sound environment and the physiological responses to traffic noises. To improve the subjective evaluation of the sound environment, the water sound was found to have stronger masking effect on rail traffic noises than the road traffic noise. To reduce the noise annoyance, SNRs at -3dB and 3dB was found to be the most effective for the conventional train noise and the high-speed train noise, respectively. Water sound at low sound level (SNR=-3dB) was also found to be effective in improving the acoustic comfort for the conventional train noise. Effect of water sound in masking the physiological impact of traffic sounds was found to be limited which depended on the traffic noise type and participants characteristics. Comparing to EDA, HR were found to be more easily affected by the water sound.

Numerical simulation and prediction of aerodynamic noise of high-speed trains

In order to improve the efficiency of high-speed train aerodynamic noise analysis and provide a feasible method for aerodynamic noise prediction, the aerodynamic noise and its influencing factors are analyzed from the perspective of the total energy (sound power) radiated to the far field per unit time by the aerodynamic fundamental noise sources (monopole, dipole and quadrupole sources). A full-scale and a 1:8 scale-down computational fluid dynamics model of a high-speed train are established. The far-field sound pressure level at several receivers and velocities is calculated by using the transient large eddy simulation and the FW-H equation. The numerical simulation results are used to predict the aerodynamic noise under specified working conditions. The research work can achieve the prediction of aerodynamic noise at other velocities using noise data at known velocities on the same noise source case, as well as the prediction of aerodynamic noise of full-scale model using data of scale-down model, and is applicable to either bogies as local noise sources or the complete vehicle as a noise source. The maximum error between the prediction and simulation result is 0.33 dBA under various working conditions, which meets the engineering calculation requirements.

Experimental and quantitative evaluation of frequency modulation caused by Doppler effect around high-speed moving sound source.

High-speed train noise remains a wayside environmental issue. For accurate noise prediction, the characteristics of a moving sound source must be revealed. In this work, the frequency modulation of sound waves emitted from a high-speed moving sound source was experimentally investigated. In the experiment, the sound field around a running train model emitting a 40 kHz pure tone was measured by an optical measurement technique, parallel phase-shifting interferometry, which can visualize instantaneous sound fields. For quantitative evaluation, a lens distortion correction was also developed and adopted for the visualization results. From the measured result of a sound source moving at a running speed of 280 km/h, the frequency modulation, known as the Doppler effect, was observed, and the measured frequency agreed well with the theoretical values.

Analysis of unsteady flow field and near-field aerodynamic noise of scale high-speed trains in long tunnel

The hybrid LES/APE method is used to simulate the unsteady flow field and the near-field aerodynamic noise of a 1/25 scale eight-coach high-speed train in long tunnel, validated by time-averaged pressure coefficients and Power Spectral Density of surface pressure from the aerodynamic wind tunnel test of a same scale two-coach train model. Train induced wind with the maximum velocity of 28 m/s in the opposite direction of train operating is formed in tunnel. Blocking effect leads to larger turbulent pressure and streamwise increment of turbulent power level from 133.7 dB to 138.2 dB, which is from130.3 dB to 133.4 dB in open air. With APE solver, three cases including tunnel with fully reflective walls, tunnel with fully absorptive walls and open air, are conducted to compare the influence of blocking effect and acoustic reflection on sound pressure. Total sound pressure level on the train body in tunnel is overall stronger than that in open air. The difference of sound power level between tunnel and open air is mostly contributed by acoustic reflection: 84.7 % at Coach 1, 84.3 % at Coach 8 and 66.0 ∼ 77.5 % from Coach 2 to Coach 7. Five peak frequencies: 520 Hz, 800 Hz, 1440 Hz, 2600 Hz and 3880 Hz are found from the frequency spectra of sound pressure of the probes in bogie cavities and pantograph grooves, in tunnel with fully reflective walls. Sound pressure modes help to clarify the generation mechanisms of peak frequencies: 520 Hz and 800 Hz are caused by the tunnel cavity resonance; 1440 Hz is caused by the first-order vertical mode from the bottom of the pantograph groove to the top of tunnel walls; 2600 Hz is caused by the first-order vertical mode from the ground to the top of bogie cavity, but 3880 Hz is not generated by simple in-phase cavity resonance.

Psychophysiological responses to traffic noises in urban green spaces

The present study aims to explore the psychophysiological impact of different traffic sounds in urban green spaces. In the experiment, 30 subjects were recruited and exposed to different traffic sounds in the virtual reality (VR) scene. The road traffic sound and three railway sounds (con-ventional train, high-speed train, and tram) with three sound levels (45, 55, and 65 dB) were used as the acoustic stimuli. Physiological responses, electrodermal activity (EDA) and heart rate (HR) were monitored throughout the experiment. Psychological evaluations under each acoustic stimuli were also measured using scales within the VR system. The results showed that both the psychological and the physiological responses were significantly affected by the traffic sounds. As for psychological responses, considerable adverse effects of traffic sounds were observed, which constantly increased with the increase of the sound level. The peak sound level was found to have a better performance than the equivalent sound level in the assessment of the psycho-logical impact of traffic sounds. As for the physiological responses, significant effects of both the acoustic factors (sound type and sound level) and the non-acoustic factors (gender and exposure time) were observed. The physiological effect of high-speed train noise was significantly differ-ent from those of the other three traffic noises. The relationship between sound level and physi-ological parameters varied among different sound groups. The variation of sound level could hardly affect the participants' HR and EDA when exposed to the road traffic noise. On the con-trary, the physiological responses were significantly affected by the sound level of rail traffic noise. By a correlation analysis, no linear correlation between the psychological evaluations and HR was found.

Tribological improvement of a high-speed train brake system and friction-induced vibration energy harvesting via a sandwich damping piezoelectric structure

A sandwich damping piezoelectric structure (SDPS) was designed to improve the wear and friction, reduce the friction-induced vibration and noise (FIVN) of high-speed train brake system, and convert friction-induced vibration (FIV) energy into electrical energy. Tribological tests were carried out to investigate the effect of the SDPS on the tribological behavior and the conversion efficiency of FIV energy into electrical energy. The results show that the proposed SDPS can convert FIV energy into electrical energy due to deformation, and the perforated structure produces greater deformation and a higher output voltage. The SDPS installed in the braking system improves the contact and wear behavior of the friction block, which reduces the FIV intensity, and can transform FIV energy into electrical energy.

A Review of Recent Research into the Causes and Control of Noise during High-Speed Train Movement

Since the invention of the train, the problem of train noise has been a constraint on the development of trains. With increases in train speed, the main noise from high-speed trains has changed from rolling noise to aerodynamic noise, and the noise level and noise frequency range have also changed significantly. This paper provides a comprehensive overview of recent advances in the development of high-speed train noise. Firstly, the train noise composition is summarized; next, the main research methods for train noise, which include real high-speed train noise tests, wind tunnel tests, and numerical simulations, are reviewed and discussed. We also discuss the current methods of noise reduction for trains and summarize the progress in current research and the limitations of train body panels and railroad sound barrier technology. Finally, the article introduces the development and potential future applications of acoustic metamaterials and proposes application scenarios of acoustic metamaterials for the specific needs of railroad sound barriers and train car bodies. This synopsis provides a useful platform for researchers and engineers to cope with problems of future high-speed rail noise in the future.

Modeling and Simulation of the Aerodynamic Noise of High-Speed Train’s Pantograph

This article aims to investigate the aerodynamic noise of the pantograph of the high-speed trains in different operating conditions. CFD technique was used to assess the acoustic noise of the pantograph components. Three-dimensional computational simulations were performed using FLUENT software. Comprehensive analyses of the acoustic pressure and the air velocity distributions were accomplished for the detailed full-scale pantograph components. Good agreement was found between the obtained results and the reported results in the literature. Vortex shedding was the main source of noise at the pantograph panhead and knee. A modified model for the pantograph was introduced to reduce the aerodynamic noise of the pantograph’s panhead. A different design profile for the collector was presented as a possible solution for the reduction of both the aerodynamic noise and the reduction of the fluctuating forces at the panhead-catenary interaction, which affects the quality of the power transmitted to the high-speed train. The cylindrical cross-section of the panhead bars was replaced with different cross-sections. It was noticed that at a speed of 250 km/hr, the use of an elliptic cross-section has resulted in an almost 23.1% reduction in the acoustic sound pressure for the pantograph.

Study on prediction in far-field aerodynamic noise of long-marshalling high-speed train.

It is still difficult to conduct numerical calculation of the aerodynamic noise of full-scale, long-marshalling, high-speed trains. Based on the Lighthill acoustic analogy theory, the aerodynamic sound source of the high-speed train is equivalent to countless micro-vibrating sound sources. An acoustic radiation model of the dipole sound source of high-speed trains is established, and a method to predict the aerodynamic noise in the far field of long-marshalling high-speed trains is proposed. By this method, combined with numerical simulation technology, the flow field, noise source, and far-field noise characteristics of high-speed trains with different marshalling numbers are studied. The improved delayed detached eddy simulation method is used for flow field calculation, to obtain aerodynamic noise source information regarding the surface of high-speed trains. The numerical calculation method is verified by wind tunnel testing. The results show that the flow field and noise source characteristics of high-speed trains with different marshalling numbers are similar. The greater the length of the train body, the longer the trailing distance of the train wake, and the stronger of a surface noise source the tail car becomes. The spatial distribution characteristics of aerodynamic noise in the far field of high-speed trains do not change significantly with the length of the train body, but the magnitude of the sound pressure level will increase with the increase in length of the train body. The middle car body parts of high-speed trains with different marshalling numbers have similar noise distributions and sound pressure levels. Based on the noise calculation results of the 3-marshalling high-speed train, the far-field noise of the 5-marshalling and 8-marshalling train models is predicted and found to be in good agreement with the far-field noise of the actual train model. The differences in average sound pressure level are 1.01 dBA and 1.74 dBA, respectively.

Step-by-Step Numerical Prediction of Aerodynamic Noise Generated by High Speed Trains

In this paper, the unsteady flow around a high-speed train is numerically simulated by detached eddy simulation method (DES), and the far-field noise is predicted using the Ffowcs Williams-Hawkings (FW-H) acoustic model. The reliability of the numerical calculation is verified by wind tunnel experiments. The superposition relationship between the far-field radiated noise of the local aerodynamic noise sources of the high-speed train and the whole noise source is analyzed. Since the aerodynamic noise of high-speed trains is derived from its different components, a stepwise calculation method is proposed to predict the aerodynamic noise of high-speed trains. The results show that the local noise sources of high-speed trains and the whole noise source conform to the principle of sound source energy superposition. Using the head, middle and tail cars of the high-speed train as noise sources, different numerical models are established to obtain the far-field radiated noise of each aerodynamic noise source. The far-field total noise of high-speed trains is predicted using sound source superposition. A step-by-step calculation of each local aerodynamic noise source is used to obtain the superimposed value of the far-field noise. This is consistent with the far-field noise of the whole train model’s aerodynamic noise. The averaged sound pressure level of the far-field longitudinal noise measurement points differs by 1.92 dBA. The step-by-step numerical prediction method of aerodynamic noise of high-speed trains can provide a reference for the numerical prediction of aerodynamic noise generated by long marshalling high-speed trains.

A Fast Approach for Predicting Aerodynamic Noise Sources of High-Speed Train Running in Tunnel

The aerodynamic noise of high-speed trains passing through a tunnel has gradually become an important issue. Numerical approaches for predicting the aerodynamic noise sources of high-speed trains running in tunnels are the key to alleviating aerodynamic noise issues. In this paper, two typical numerical methods are used to calculate the aerodynamic noise of high-speed trains. These are the static method combined with non-reflective boundary conditions and the dynamic mesh method combined with adaptive mesh. The fluctuating pressure, flow field and aerodynamic noise source are numerically simulated using the above methods. The results show that the fluctuating pressure, flow field structure and noise source characteristics obtained using different methods, are basically consistent. Compared to the dynamic mesh method, the pressure, vortex size and noise source radiation intensity, obtained by the static method, are larger. The differences are in the tail car and its wake. The two calculation methods show that the spectral characteristics of the surface noise source are consistent. The maximum difference in the sound pressure level is 1.9 dBA. The static method is more efficient and more suitable for engineering applications.

Flow structure and far-field noise of high-speed train under ballast track

The flow structure and far-field noise of 1:8 three-carriage high-speed train under ballast track were investigated. The random surface of ballast track was established using the stochastic function method, and the flow field and far-field noise were calculated through large eddy simulation and FW-H equation at 250 km/h. Based on the wind tunnel test, the far-field noise errors of simulation are lower than 3 dB at most frequencies, indicating that the simulation method has an acceptable prediction accuracy. The bogies' sections were analyzed through reduced-order decomposition method, and the side vortex is found as the typical unsteady flow structure, while the near-ground flow is chaotic. Under the moving smooth ground, the first three bogies are affected by the jet shear layer generated under the cowcatcher. The flow structure is more chaotic, and the dipole sound sources’ energy is also stronger than that under the ballast track. The total sound pressure level of far-field noise under ballast track is 78.4 dB(A), which is 1.1 dB lower than that under the moving smooth ground. Considering the sound absorption effect of ballast track, based on the sound absorption coefficients of 17 cm ballast layer, the far-field noise is further reduced by 3.9 dB.

An acoustic design procedure for controlling interior noise of high-speed trains

Excessive interior noise in high-speed trains affects riding comfort of both drivers and passengers, therefore, it is a key indicator of product competitiveness for manufacturers. Past academic researches on train interior noise control focus primarily on mechanisms and characterisations of noise sources and vibro-acoustical behaviours of car-body structures, and these two aspects are often dealt with separately, unable to lead a systematic procedure for controlling high-speed train interior noise. On the other hand, many practical studies are problem-based, aiming at finding root causes of, and remedies for, a noise problem which has already occurred. They not only lack of systematisms, but also are time- and resource-consuming. To design low interior noise and to make sure the actual product based on the design does meet noise target, an acoustic design procedure is needed. Based on the experience of many years’ research in the field of railway noise and vibration, especially that gained in the development of the Chinese ‘Fuxing’ high-speed trains, such an acoustic design procedure for interior noise is summed up and described in this paper. Application of the procedure to the development of a to-be made high-speed train is also presented, together with results simulated and measured on the developed train, showing that the design goal of 3 dBA noise reduction is met.

Study on the flow behaviour and aerodynamic noise characteristics of a high-speed pantograph under crosswinds

The aerodynamic noise of high-speed trains increases significantly under crosswinds. Researches have typically focused on the characteristics of aerodynamic loads and the corresponding safety issues, with less attention to flow-induced noise characteristics. In the present paper, the near-field unsteady flow behaviour around a pantograph was analysed using a large eddy simulation. The far-field aerodynamic noise from a pantograph was predicted using the Ffowcs Williams-Hawkings acoustic analogy. The results showed that asymmetric characteristics of the flow field could be observed using the turbulent kinetic energy and the instantaneous vortexes in crosswind conditions. Vortex shedding, flow separation and recombination around the pantograph were the key factors for aerodynamic noise generation. The directivity of the noise radiation was inclined towards the leeward side of the pantograph. The aerodynamic noise propagation pattern can be considered as a typical point source on spherical waves when the transverse distance from the pantograph geometrical centre is farther than 8 m. The sound pressure level grew approximately as the 6th power of the pantograph speed. The peak frequency exhibited a linear relationship with the crosswind velocity. The numerical simulation results and wind tunnel experiments had high consistency in the full frequency domain, namely, the peak frequency distribution range, the main frequency amplitude and the spectral distribution shape.

Study on Characteristics of the External Aerodynamic Noise of High-Speed Trains

Study on Characteristics of the External Aerodynamic Noise of High-Speed Trains

Influence of the Friction Block Shape and Installation Angle of High-Speed Train Brakes on Brake Noise

Abstract In this study, experiments are conducted to evaluate the effects of friction block shapes and installation angles on the brake noise of high-speed trains on a customized small-scale brake dynamometer. Friction blocks in three different shapes (circle, triangle, and hexagon) and triangular/hexagonal friction blocks at different installation angles are used in the tests. The results indicate that the circular and triangular blocks exhibit low sound pressure with multiple harmonics, whereas the hexagonal friction block produces the highest sound pressure with a single dominant frequency. This difference is attributed to the high contact pressure and severe wear on the surface of the hexagonal friction block. Differences in the installation angle of the triangular/hexagonal friction blocks affect wear debris behavior, distribution of contact pressure, and contact state of the friction interface, consequently influencing noise performance.

Simulation Analysis on Noise Reduction Effect of Sound Barriers with Different Geometric Shapes for High-Speed Train

In order to study the noise reduction effect of different geometrical sound barriers on high-speed train aerodynamic noise, simulation studies were carried out on three shapes of sound barriers. The RNG k-epsilon turbulence model was used to calculate the aerodynamic drag of the high-speed train. Based on the large eddy simulation LES method and the FW-H acoustic analogy equation, the pulsating pressure of the train was extracted as the far-field noise source, and the noise reduction capabilities of the upright, semi-circular, and quarter-circular sound barriers were compared. The results show that the semi-circular sound barrier has the largest average insertion loss in far field, and its frequency response characteristics present the best match to the aerodynamic noise of high-speed train. Therefore, the semicircular sound barrier has the best noise reduction effect.

슬라브 도상 궤도 터널 주행 고속열차 차내 소음 특성 및 전달 기여도 분석

본 논문에서는 슬라브 도상 궤도 터널 내의 차량 소음 현황, 주행 중 차내소음에의 음원의 전달 기여도 분석을 수행한 결과를 소개하였다. 개활지 운행 시에는 차륜과 레일이 접촉하여 주행함으로써 차량 구조를 통해 전달되어 차내로 방사되는 구조기인 소음의 기여도가 전반적으로 높은 데에 비하여 슬라브 도상 궤도 터널 내 차내 음압 레벨은 대상 차량 차체외부패널의 기여도가 크게 나타났으며, 실내 음압의 증가는 터널 내에서의 차량 외부에 의한 강한 음압가진이나 그 외의 다른 효과로부터 발생한다고 판단할 수 있다. 본 대상 차량의 경우 차량 외부로부터의 공기기인 소음 유입보다는 터널 내의 음압가진을 통한 외부 차체 상부와 지붕에서의 차내로의 유입이 차내 소음 기여도가 가장 큰 것으로 나타났다. 궤도 유형, 터널 통과 등 상이한 주행 조건하에서 측정된 소음데이터에 대한 심리음향적 지표 분석 결과를 하나의 예시로 제시하여, 단일 값으로 표현되는 총합소음레벨값의 증감의 변화뿐 아니라 승객의 청감과 관련된 지표 분석도 차내소음 기준 및 저감목표 설정을 위해서는 필요함을 고찰하였다.