The Theoretical Research And Numerical Simulation Of Aerodynamic Noise For High-Speed Train

With the increasing of train speed, the aerodynamic noise of the high-speed train is becoming more and more important and has become the main noise source of high-speed train. The influence on the noise pollution of external and internal enviromen of train can not be ignored. Reducing the aerodynamic noise has become one of the main keys to control the noise of the high-speed train. In this disseration, both theoretical study and numerical simulation are used to study the aerodynamic noise of the high-speed train, and its main works include:1. Theoretical study of aerodymic noise of the high-speed train in the far field. Based on the fluid acoustic theory, combined with the actual boundary condition of running high-speed train, this dissertation establishes the theoretical prediction formula of aerodymic noise in the far field. This formula shows that the sound pressure in the far field can be similarly depicted by the fluctuating pressures on the outside surface of the body. The airflow-generated fluctuating pressure on the surface of the body is the source of aerodynamic noise.2. Numerical simulation method of external flow field of the high-speed train. This dissertation establishes the physical and mathematical models of three dimensional flow field of the high-speed train, computes the external steady-state flow field of the high-speed train on the ground, embankment, viaduct and computes the external transient flow field of the high-speed train on the ground as well. Then, the dissertation analyzes the flow field. The results show that the greater of relative velocity, the more dense distribution of pressure, or the stronger of pressure gradient leads to the more intense changes of fluctuating pressure. The fluctuating pressure on the surface of the train body has random characteristics and varies with time, and the spectral analysis shows that the fluctuating pressure has broadband characteristics.3. Calculation and analysis of noise sources on the body surface of the high-speed train. Based on standards k-εturbulence model, this dissertation calculates noise sources on the body surface of the high-speed train on the ground, embankment and viaduct using Broadband Noise Source Model. The results show that the distribution of noise sources on the body surface is quite similar and the difference of noise sources intensity is very small under this three kinds of operating conditions. The results also show that the values of sound power level and surface sound power level are not more than 2dB. But with the increasing of train speed, the sound power and surface sound power on the body significantly increase. Thus, it is very important to reduce the aerodynamic noise to develop high-speed train.4. Calculation and analysis of the far-field aerodynamic noise of the high-speed train. Based on the SST k-ωturbulence model, this dissertation calculates the far-field aerodynamic noise of high-speed train on the ground using Ffowcs Williams and Hawkings Model. The characteristics of the far-field aerodynamic noise of the high-speed train are educed by studying the sound pressure level and frequency spectrum of measuring points. The computational results show that as the velocity of the high-speed train increases the effective sound pressure increase but the spectrum characteristics of sound pressure dose not change.5. Study on theoretically claculating method of interior aerodynamic noise of the high-speed train. This dissertation establishes the theoretically claculating method of interior aerodynamic noise of the high-speed train using the Statistical Energy Analysis (SEA) theory. The SEA model is programed by the software—Fortran so as to calculate the interior aerodynamic noise of high-speed train on the ground with the speed of 350km/h. At last this dissertation studies the methods of reducing the interior aerodynamic noise.