高速列车噪声源声功率与速度的函数关系

为了解决既有对数经验公式无法拟合高速列车显著声源贡献率与速度的函数关系这一问题，使用轮辐声阵列进行高速列车车外声源识别试验；根据显著声源位置对列车表面进行区域划分，量化分析显著声源区域的声功率级和声功率贡献率与速度之间的关系；在既有对数经验公式的基础上，根据不同种类噪声声功率随速度的变化特性，建立新的拟合公式；结合列车噪声测试数据对新的拟合公式进行验证. 研究结果表明:列车以350 km/h运行时，下部区域对列车总辐射噪声的贡献率占70%以上，升弓区域对局部区域声功率的影响最显著，超过50%；随着速度的增长，下部区域的贡献率逐渐减小，弓网区域逐渐增大，显著声源区域的贡献率变化先快后慢，最后趋于稳定；利用新的拟合方法得出，列车声源区域的声功率级和声功率贡献率与速度的拟合度基本都在0.9以上. 

Functional Relationships between Sound Powers Radiated from Noise Sources of High-Speed Train and Its Speed

To solve the problem that the existing logarithm empirical formula cannot satisfactorily fit the relationship between the sources contribution rate and the speed, the microphone array was used to identify the external sound sources of a high-speed train at different speeds. Dividing the train surface into sub-regions with the location of the known main noise sources, the relationship between sound power level and its contribution rate of main noise sources sub-region and train speed were analyzed quantitatively. Then, according to the characteristic of different kinds of noise sound powers increment rate with speed, the new fitting formula was established based on the existing logarithm empirical formula. Finally, the new formula was verified on the noise data of different train. The results show that when the train runs at 350 km/h, radiated noise from the lower region of railway system dominate the total radiated noise, which account for more than 70%. The sound power of the rising pantograph region is significant in the local region as well, which account for more than 50%. With the speed increase, the contribution rate of lower region decrease and the pantograph regions increase, and each regions change rapidly first and then slowly, finally become stable. Using the advanced fitting method, the fitting degrees of sound power level and sound power contribution rate with speed in the source regions of the train are all above 0.9.