Sound Source Localisation for a High-Speed Train and Its Transfer Path to Interior Noise

Noise is one of the key issues in the operation of high-speed railways, with sound source localisation and its transfer path as the two major aspects. This study investigates both the exterior and interior sound source distribution of a high-speed train and presents a method for performing the contribution analysis of airborne sound with regard to the interior noise. First, both exterior and interior sound source locations of the high-speed train are identified through in-situ measurements. Second, the sound source contribution for di erent regions of the train and the relationships between the exterior and interior noises are analysed. Third, a method for conducting the contribution analysis of airborne sound with regard to the interior noise of the high-speed train is described. Lastly, a case study on the sidewall area is carried out, and the contribution of airborne sound to the interior noise of this area is obtained. The results show that, when the high-speed train runs at 310 km/h, dominant exterior sound sources are located in the bogie and pantograph regions, while main interior sound sources are located at the sidewall and roof. The interior noise, the bogie area noise and the sound source at the middle of the coach exhibit very similar rates of increase with increasing train speed. For the selected sidewall area, structure-borne sound dominates in most of the 1/3 octave bands.

An investigation into high-speed train interior noise with operational transfer path analysis method

Passengers’demands for riding comfort have been getting higher and higher as the high-speed railway develops.Scientific methods to analyze the interior noise of the high-speed train are needed and the operational transfer path analysis(OTPA)method provides a theoretical basis and guidance for the noise control of the train and overcomes the shortcomings of the traditional method,which has high test efficiency and can be carried out during the working state of the targeted machine.The OTPA model is established from the aspects of“path reference point-target point”and“sound source reference point-target point”.As for the mechanism of the noise transmission path,an assumption is made that the direct sound propagation is ignored,and the symmetric sound source and the symmetric path are merged.Using the operational test data and the OTPA method,combined with the results of spherical array sound source identification,the path contribution and sound source contribution of the interior noise are analyzed,respectively,from aspects of the total value and spectrum.The results show that the OTPA conforms to the calculation results of the spherical array sound source identification.At low speed,the contribution of the floor path and the contribution of the bogie sources are dominant.When the speed is greater than 300 km/h,the contribution of the roof path is dominant.Moreover,for the carriage with a pantograph,the lifted pantograph is an obvious source.The noise from the exterior sources of the train transfer into the interior mainly through the form of structural excitation,and the contribution of air excitation is non-significant.Certain analyses of train parts provide guides for the interior noise control.

Investigation on Major Noise Sources of Vehicle Diesel Engine Based on Sound Intensity Measurement

In order to reduce the noise and vibration of the diesel engine,it is crucial to exactly identify the engine noise source character.Based on "two-microphone" method,the sound intensity measurement of a vehicle four-stroke diesel engine was carried out in a hemi-anechoic chamber.Then the sound intensity contour maps were obtained from the measurement results and the main noise components of different frequencies on all the measurement surfaces were picked out to construct contour maps.By analysizing the relationship between the characteristics of contour maps and the space distribution of the engine compartment,the major sources of the exterior radiation noise of the diesel engine were identified.The results provided a creditable basis for improving the noise performance of the engine in the next phase.

Analysis of external noise spectrum of high-speed railway

A schematic to make the spectra of the exterior noise of high speed railway was put forward. The exterior noise spectrum was defined based on the characteristics of the high-speed train exterior noise. Its characteristics considered here include identifying the exterior main sources and their locations, their frequency components including the Doppler effect due to the noise sources moving at high speed, the sound field intensity around the train in high-speed operation, the sound radiation path out of the train, and the pressure level and frequency components of the noise at the measuring points specified by the International Organization for Standardization(ISO). The characteristics of the high-speed train exterior noise of the high speed railways in operation were introduced. The advanced measuring systems and their principles for clearly indentifying the exterior noise sources were discussed in detail. Based on the concerned noise results measured at sites, a prediction model was developed to calculate the sound level and the characteristics of the exterior noise at any point where it is difficult to measure and to help to make the exterior noise spectrums. This model was also verified with the test results. The verification shows that there is a good agreement between the theoretical and experimental results.

Scanning paths for estimating sound power of noise sources by sound intensity scanning method

A mathematical model of deterndulng sound power by using the scanning method is developed. It is assumed that the scanning speed is constant and the noise source is stationary The accuracy of estimating sound power along some simple paths on the surfaces such as rectangle, disc and hemisphere is analyzed. It is argued that the accuracy of estimating sound power is strongly depended on a suitable selection of scan path. The accurate estdriation of sound power can be made by scanning along some simple paths.

油田通井机噪声危害分析与治理

目的针对油田通井机噪声危害的问题,寻求合理的解决方案。方法选择某油田油气井下作业单位的柴油驱动通井机作为研究对象,通过采取振动与噪声测试,分析TJL-12通井机主要噪声源和传播途径,对驾驶舱和发动机舱进行隔声和吸声,对调节阀处进行消声等设计和改造,降低噪声接触水平,使其低于国家职业接触限值要求,改善油气井下作业环境。结果噪声检测结果显示,通井机司钻接触噪声强度由95.2 dB(A)降至84.2 dB(A),低于85 dB(A)的噪声接触限值。结论噪声危害分析和综合治理方案可有效解决油田行业在修井作业时通井机噪声危害控制难题。

基于CEEMDAN-WSVD组合串扰消除法车内噪声源识别

为解决车内噪声源识别中结构路径易受外部因素干扰,以及多源振动串扰影响,导致采集的工况数据存在噪声等问题,提出基于自适应噪声的完备集合经验模态分解(Complete Ensemble Empirical Mode Decomposition with Adaptive Noise,CEEMDAN)的CEEMDAN-WSVD组合去噪法,该方法利用自适应加噪特征避免模态混叠现象发生,引入样本熵对高频含噪分量进行小波变换(Wavelet Transform,WT),实现一层降噪后进行重构;并采用奇异值分解(Singular Value Decomposition,SVD)对重构信号获取主分向量,同时使用主分量衰减方法剔除较小主分量,实现二层降噪。运用模拟仿真信号验证上述方法对复杂含噪信号有降噪效果。通过对采集的工况数据降噪处理,计算路径传递率并得到贡献量。将各降噪方法应用于工况传递路径模型中对比分析,发现经过本文方法降噪后模型的合成响应与实测响应准确性较高,降噪效果较优。

煤炭筛分破碎车间噪声治理及智能监测研究

工业噪声造成的职业性噪声聋已位列我国职业病第二位。目前煤炭行业职业健康重点关注粉尘治理,对噪声治理和监测预警的研究较少。为了探索煤炭生产过程噪声治理及监测方案,以西湾煤矿筛分破碎车间噪声污染治理为例,基于振动筛、刮板输送机和溜槽等噪声产生原因分析,从声源降噪和传播途径降噪等方面提出了多种噪声治理方案:将振动筛筛板更换为全聚氨酯筛板,将弹簧更换为橡胶空气弹簧;在溜槽内表面的耐磨衬板与溜槽钢板之间铺设缓冲橡胶板;将刮板输送机预警方式改为机电方式;在高噪声设备外安装隔声罩;溜槽敷设约束阻尼层。同时,为实现噪声实时监测及预警,基于深度学习声音识别技术,设计了噪声智能监测预警系统。研究结果表明:经过噪声综合治理,筛分破碎车间的噪声可达到国家标准规定,即不超过职业接触噪声限值97dB(A);噪声智能监测预警系统可对噪声进行智能监测,并根据分区分级原则对噪声进行实时预警。对筛分破碎车间进行噪声治理及智能监测,不仅能保证生产人员的职业健康,还能对设备健康实现预警,延长设备使用寿命。

冰箱压缩机高频噪声识别及优化

当前冰箱压缩机高频噪声问题突出,高频噪声听感差易引发用户投诉,识别冰箱压缩机的高频噪声问题,并进行相关优化已迫在眉睫。针对当前的冰箱压缩机易出现的高频噪声问题,以某款定速机型为例,从噪声源和传递路径进行研究,针对某款定速机型的2500 Hz、4000 Hz、5000 Hz等高频噪声问题进行了深度分析并优化。测试结果显示,采用此优化方案能够明显改善其高频噪声问题,为冰箱压缩机高频噪声问题改善提供了相关思路和理论依据,对后续的产品设计具有一定的指导意义。

有源降噪通路辨识的人因参数几何模型

研究了一种基于人因参数几何模型的声学通路辨识策略,可用于有源降噪技术中的通路辨识环节,以降低因人体姿态改变而导致的降噪性能退化。该策略利用深度相机输出的点云数据提取人因参数并构建几何模型,通过仿真和人工神经网络预测声学通路的传递函数矩阵。结果表明,人因参数几何模型的降噪性能与点云模型接近,适用于参数化扫描仿真。进一步通过实验验证了仿真的准确性以及所提策略的可行性。实验结果还表明,人体姿态改变会导致声学通路传递函数发生复杂且显著的变化,说明实际应用应考虑人体姿态改变所带来的影响。

某纯电SUV车型低频路噪问题分析及优化

为优化某纯电运动型多用途汽车(SUV)的若干低频路噪问题,文章依据路噪产生的机理,通过路噪传递路径分析,并结合整车模态分布,对该车型激励源、传递路径和响应进行了详细排查分析优化,并有效抑制了整车低频路噪。文章对整车前后排的不同频率噪声进行识别,分别为前排30 Hz附近耳压感、前排200 Hz附近空腔声和后排75 Hz附近敲鼓声,通过路噪源头控制、路径隔振提升及响应优化将整车低频路噪控制到较好水平,主观评价良好。文章所识别的低频路噪问题是整车路噪开发过程中较典型的问题点,分析优化思路对整车路噪问题分析排查及试验方法有一定的指导意义。

滚筒洗衣机脱水振动噪音快速优化方案

本文主要介绍了一种洗衣机项目开发过程中快速进行振动噪音优化改善的方案。由滚筒洗衣机脱水振动噪音问题引入,根据噪声频谱峰值分析主要为箱体结构振动噪音。并由产生振动噪音的激励源、传递路径和响应部件三个关键因素,分别设计改善方案。最终通过分析各个方案的改善周期和改善成本,快速筛选最佳改善方法。实现了不增加成本和开发设计时间的情况下,有效降低脱水振动噪音且满足项目噪音设计要求。

整车噪声传递函数试验方法研究

整车噪声传递函数是评价整车结构噪声传递特性的关键指标,噪声传递函数一般可以通过仿真计算或试验测试进行获取。本文以承载式车身和非承载式车身为研究对象,分别使用力锤法和体积声源法对其进行整车噪声传递函数测试。通过对测试结果进行分析,探讨两种试验方法的优劣,可为不同结构车型噪声传递函数的准确测试提供指导和参考。

柴油机薄壁件噪声源识别及降噪研究

针对某柴油机薄壁件辐射噪声问题,以气阀罩盖为研究对象,测试与仿真相结合实现结构传递噪声与透射噪声的识别与分离。基于参数型修正法优化的有限元模型,分别以采集的模态扩展线框测点振动信号和螺栓处加速度信号为输入计算振动及声学响应并进行噪声源识别;通过隔声识别法试验验证噪声源识别结果的准确性;并研究气阀罩盖采取隔声减振与吸声措施时对整机噪声的影响。结果表明:模态扩展法与隔声识别法的噪声源识别结果一致,在400~4000 Hz频段以透射噪声为主,且透射噪声占比约80%;气阀罩盖采用隔声减振措施时,在内侧贴复合板的效果要优于外侧;采用轻量化低噪声复合气阀罩盖时,整机可降低3.0 dB(A)。为发动机薄壁件噪声源识别及降噪提供新思路。

传递路径分析在车内声品质优化中的应用

针对某款车型在40km/h粗糙路面行驶时,车内主驾耳旁噪声声品质主观感受较差的问题。首先,采用传递路径分析(Transfer Path Analysis,TPA)方法得到每条路径对于车内驾驶员耳旁噪声的贡献量。其次,基于遗传算法(Genetic Algorithm,GA)优化BP神经网络的权值和阈值建立车内声品质预测模型,实现传递路径分析与声品质相结合,有效识别出48条结构路径中后副车架左后、右后和右前安装点Z向三条路径对车内噪声烦躁度贡献最大。最后,结合模态分析和频谱分析确定为后副车架模态问题。通过调整后副车架衬套刚度,车内主驾耳旁噪声声品质得到有效改善。

锯齿尾缘构型降低圆柱-叶栅干涉噪声的实验研究

通过在叶栅上游放置圆柱产生各向异性的湍流尾迹,并与下游叶片相互干涉产生干涉噪声,研究了仿生学锯齿尾缘构型对圆柱-叶栅干涉噪声的影响。针对西北工业大学航空叶轮机气动力学与气动声学实验室(TAAL)低压涡轮平面叶栅,在不同来流速度的情况下,使用远场圆弧阵列测量了叶栅远场噪声,并基于CLEAN-SC数据处理算法使用由31个传声器组成的线阵列测量识别了不同叶栅的尾缘噪声,得到了圆柱尾迹来流下锯齿尾缘构型的降噪效果。实验结果表明,不同锯齿尾缘构型的降噪效果存在差异,当来流为圆柱尾迹时,对叶栅尾缘噪声的识别测量结果显示此时锯齿尾缘降噪效果有限,最佳降噪量仅为1.296dB,当来流速度较高时,采用的锯齿尾缘构型无法降低圆柱-叶栅干涉尾缘噪声。

纯电动汽车车内噪声源信号的降噪研究

传递路径分析是识别车内噪声源技术的重要研究方法,但试验车辆在运行工况下,其输入端中各路径易受外部因素干扰,导致采集的噪声源信号中含有噪声。针对此问题,本文提出采用集合经验模态分解与小波阈值的方法对噪声源信号进行降噪处理,其中,引入了相关系数方便更精确的识别出高频分量进而达到更优降噪效果。以某款国产纯电动汽车为试验车辆,采集加速工况的时域数据,应用搭建的工况传递路径模型对车内噪声源贡献量分析并进行降噪处理。结果表明,本文提出的降噪方法在车内噪声源信号中降噪的可行性。

地铁车内空气声传递路径分析及板件隔声性能优化

基于统计能量法建立地铁车内噪声仿真预测模型,分析车体结构在空气声传递路径上的薄弱环节。通过地铁车内噪声仿真预测及传递路径分析,指导车体结构的减振降噪设计。基于板件隔声的基本原理,研究地铁车体板件隔声量的全频段计算方法,分析板件结构参数对其隔声性能的影响规律。综合考虑车体刚度、轻量化及隔声性能,提出地铁车体结构减振降噪优化设计方案,从而降低车内噪声,提高地铁车辆乘坐舒适性。

车内加速粗糙声分析与控制

针对某车型车内300~400 Hz和460~560 Hz加速粗糙声问题,利用工况传递路径方法进行整车状态工况传递路径分析,识别出了车内两个频段粗糙声的主要贡献路径。基于从主要贡献路径到关联激励源的分析研究思路,逐一识别引起车内两个频段粗糙声的原因。研究发现300~400 Hz粗糙声主要受发动机曲轴一阶扭振影响,460~560 Hz粗糙声主要由左悬主动侧支架共振导致。针对问题原因,提出对应的优化改进方案,进行试验验证。结果表明,车内两个频段粗糙声改善明显,车内加速声品质得到有效提升。

基于Clean-SC的航空发动机整机喷流噪声定位识别研究

针对航空发动机整机喷流噪声定位识别难题,开展了基于Clean-SC声源成像识别技术结合线形传声器阵列的航空发动机整机喷流噪声定位识别方法研究。以小涵道比涡扇发动机为对象进行了测试验证,获取了发动机整机喷流噪声的主要声源特性。该特性沿着发动机喷流轴线方向以及与发动机轴线呈一定角度的方向分布,不随发动机状态的变化而变化,且主要为1000 Hz以下的低频声源。证明了本文方法的可行性,为后续航空发动机整机喷流噪声的声源定位研究奠定了基础,具有重要的工程应用价值。