车头长度对高速列车气动特性与声场特性影响的数值分析及降噪研究

Numerical Analysis of Influence of Head Length on Aerodynamic and Sound Field Characteristics of G-Series High-Speed Train and Research on Noise Reduction

在高速列车车身长度保持一定的情况下,不同长度的车头会对列车整体的气动特性(阻力、升力)、列车表面噪声源分布变化、远声场特性(A计权声压级、脉动声压、声场频率等)造成不同的变化。进行三维建模之后,宽频噪声模型采用RNG k-epsilon模型做定常计算,FW-H声学模型采用大涡模拟(LES)模型进行瞬态计算,对时速为350km·h-1,5~13m不同长度车头的高速列车简化模型进行数值模拟,分析气动特性和声场特性。结果表明:高速列车的整车阻力随车头长度增加先呈现减小趋势,当车头长度达到13m时整车阻力开始增大;高速列车远场声压级随车头长度的增加呈现增加态势。综合阻力与远场声压级随车头长度的非线性变化规律,在高速铁路简化模型下最佳车头长度为9m,可保证在减小行车阻力同时控制噪声对环境的污染。研究结论可为高速列车的减阻降噪提供参考。

Under the condition of maintaining a certain body length of G-serieshigh-speed train,different lengths of train head will lead to different changes in the aerodynamic characteristics(drag and lift)of the train as a whole,the noise source distribution on train surface and far sound field characteristics(A weighted sound pressure level,pulse sound pressure and sound field frequency,etc.).After three-dimensional modeling,the RNG k-epsilon model is used for the constant calculation of broadband noise model.The large eddy simulation(LES)model is used for the transient calculation of FW-H acoustic model.The simplified model of a G-series high-speed train with the speed of 350 km·h-1 and with different lengths of train head from 5 m to 13 m is simulated to analyzethe aerodynamic characteristics and sound field characteristics.Results show that the whole vehicle resistance of G-series high-speed train decreases firstwith the increase of train head length.When the length of train head reaches 13m,the whole vehicle resistance begins to increase.The far-field sound pressure level of G-series high-speed train increases with the increase of train head length.The nonlinear variation rules of comprehensive resistance and far-field sound pressure level vary with the length of train head.The optimal train head length is 9 m under the simplified model of G-series high-speed train,which can ensure that the traffic resistance is reduced while the noise pollution tothe environment is controlled.The research results can provide reference for the drag and noise reduction of G-series high-speed trains.