中文摘要：

基于Realizableκ-ε湍流模型的延迟分离涡模拟（DDES）方法,求解不同缩比尺度和来流速度下列车周围非定常流场.通过改变模型缩比尺度和来流速度来研究列车非定常气动特性的雷诺数效应和尺度效应.研究结果表明：随雷诺数增加,各节车气动阻力系数均方根基本呈现减小趋势,且波动明显;随雷诺数增大,列车各节车气动阻力系数和升力系数标准差均先减小后增大,且波动明显;气动力系数功率谱密度随雷诺数增大而变小;雷诺数对气动力系数主频有影响,但无明显规律;列车气动力的尺度效应显著,随雷诺数增大,列车气动力的尺度效应减弱,且列车升力的尺度效应相对显著;列车非定常气动阻力和升力振动的尺度效应随雷诺数增大而减弱,且列车非定常升力振动的尺度效应更加显著;尺度效应不改变列车气动力以低频为主的振动特性和列车气动力功率谱密度的分布规律,对气动力振动主频及其功率谱密度有显著影响.

英文摘要：

In the investigation, the unsteady flow fields around the train at different model scales and different flow velocities are solved by means of the delayed detached eddy simulation （DDES） method of the realizable κ-ε turbu- lenee model. Then, the Reynolds number effect and scale effect of the unsteady aerodynamic characteristics of the train are discussed by changing the model scale and the flow velocity. The results show that （ 1 ） with the increase of the Reynolds number, the RMS （ Root Mean Square） of the aerodynamic drag coefficient of the train decreases but fluctuates obviously ; （2） as the Reynolds number increases, the SD （ Standard Deviation） of the aerodynamic drag coefficient and lift coefficient of the train first decrease and then increase, and also fluctuate obviously ; （ 3 ） the PSD （Power Spectrum Density） of aerodynamic coefficients decreases with the increase of the Reynolds num- ber; （4） the Reynolds number can affect the basic frequency of aerodynamic coefficients, but without obvious rules; （5） the aerodynamic force of trains brings about a significant scale effect; （6） with the increase of the Reynolds number, the scale effect of the aerodynamic force decreases, and the scale effect of the lift force becomes relatively significant ; （7） the vibration scale effect of the unsteady drag and lift decreases with the increase of the Reynolds number, and the vibration scale effect of the unsteady lift force is more obvious than that of the unsteady drag; and （8） the scale effect has no effect on the vibration characteristics based on low frequencies and the PSD distribution of the aerodynamic force, but greatly affects the vibration frequency of the aerodynamic force and its PSD.