高速磁浮列车气动噪声分布规律研究

本文基于上海线高速磁浮列车现场噪声测试,结合数值仿真分析了磁浮列车行驶时的噪声特性以及气动噪声分布规律．数值仿真采用延时分离涡结合声比拟的方法,并对比现场测试噪声数据,给出了高速列车气动噪声特性以及噪声源分布规律．研究结果表明：列车行驶时噪声时程呈现很强脉冲性,频率小于100 Hz噪声主要来源于与高架桥梁结构振动相关的二次辐射噪声,特别是次声频段内,桥梁自振会产生显著的噪声．磁浮列车表面气动噪声分布规律与噪声频率相关,低频噪声与列车的车尾涡脱相关,高频噪声由车头边界层分离以及再附着、车身边界层流动等引起,而中频噪声主要产生于列车底部、抱轨与轨道梁表面相对运动作用．因此,高速磁浮列车除了要重点考虑车头、车尾的气动外形对气动噪声的影响外,还应考虑轨道间隙处气动噪声及其分布规律．

Research on the Aerodynamic Noise Distribution Laws for High-Speed Maglev Train

In this paper, the characteristics of train passing noise and the aerodynamic noise distribution laws were investigated through noise tests on site for high-speed maglev trains, combined with numerical simulations. In the numerical simulations, the aerodynamic noise characteristics of high-speed trains and the distribution of noise sources were obtained using the delayed detached Eddy Simulation model and the Lighthill acoustic analogy model, compared with the on-site test data. The results show that the train passing noise has the highly impulsive characters, and the noise with frequency less than 100 Hz mainly comes from the secondary radiation related to the vibration of bridge structures. Especially in the infra-acoustic frequency band, significant noise is produced from the self-vibration of bridge. The distribution of aerodynamic noise source on the maglev-train surface is closely related to the noise frequency. The low-frequency noise is mainly associated with rear train vortex shedding. The high-frequency noise is associated with the boundary layer flow separation and reattachment near the train head together with the boundary flow on the train surface. The intermediate frequency noise is mainly generated by the relative motion between the train bottom and the up-face of track beams. Therefore, for the high-speed maglev train, the aerodynamic noise at the track gap and its distribution laws, besides the shape of train head and train tail, should be considered for the investigation of the aerodynamic noise.