The Numerical Simulation Of CRH2 Hight-Speed Train’s Aerodynamic Noise And Its Influence

While the operation speed of high-speed train keeps on augmenting, the aerodynamic noise outweighs the rolling noise thus becoming the primary noise source. With increasingly stringent environmental regulations, railway noise pollution greatly hindered the development of high-speed rail. Reducing aerodynamic noise has becomean important research and design issue of high-speed train. Aerodynamic noise is caused byturbulent motion of airflow around train’s surface. In this paper, based on the theory of Lighthill acoustic analogy, the author studies the surface dipole noisesource distribution and spectral characteristics of a CRH2 high-speed train at different speeds. Then using the surface sources as boundary condition, analyzes the aerodynamic noise far-field distribution at different frequencies. Meanwhile the noise reduction effect of the vertical sound barrier on the far-field aerodynamic noise distribution and the sound pressure level at standard testing points are further investigated.1.The analysis of the external flow field. Building CRH2 high-speed train model and its flow field calculation model, selecting the ideal compressible fluid model, Large Eddy Simulation methodis employed in calculating the external flow field of the high-speed train and the surface fluctuating pressure is then obtained.2.The analysis of surface dipole source. Based on the theory of Lighthill acoustic analogy, the surface fluctuating pressure can be converted to the surface dipole source. Comparing the distribution and spectral properties of surface dipole source at different speeds, the results show that aerodynamic noise is of broadband type with its intensity increasing with flow speed. Surface dipole sources at locations like bogies, carriages joints, spoilers are paid great attention to due to the fact that these locations provide the most strong noise sources.3.The analysis of far-field aerodynamic noise. With the surface dipole source as the boundary condition, the high-speed train far-field aerodynamic noise distribution are obtained by solving the Helmholtz equation. Analyzing the far-field radiation law of surface dipole source, the results show that far-field aerodynamic noise level increases with increasing speed. The aerodynamic noise directivity enhances with increasing frequency. There are still large SPL at standard measuring points.4.The impact of vertical sound barrier on the aerodynamic noise. In circumstances wheresound barrierexists, far-field distribution of the aerodynamic noise can be got with the boundary condition of surface dipole source and sound barrier. The comparison of the results shows that the sound barrier can hinder the dipole sound source in the horizontal direction of propagation. It can effectively reduce the near the ground noise level at the railway line.