【作者】 孙朋朋；

【导师】 王耘； 胡树根； 宋小文；

【作者基本信息】 浙江大学 ， 机械设计及理论， 2012， 硕士

【摘要】 随着列车时速不断提高,列车与空气间的相互作用逐渐剧烈,列车的空气动力学成为不可忽视的问题。列车时速在300km/h时,空气阻力占总阻力的85%左右。因此,列车的空气阻力是列车总阻力的主要组成部分,列车空气阻力与其外形密切相关,且随着运行速度的提高空气阻力所占总阻力的比例也越来越高,所以研究和改善高速列车气动特性、减小高速列车气动阻力、提高能源利用率等受到科学界和工业界的高度重视。论文以日趋成熟的高铁技术为背景,以CHR2高速列车为研究对象,在综述非光滑表面减阻研究进展及数值模拟在列车设计中的应用后,将非光滑表面运用于列车表面在具有良好的气动外形基础上求得更好的减阻效果。本文在模拟过程中利用UG建好的36种具有非光滑表面的列车模型通过Hypermesh和ICEM CFD划分出非结构网格,应用Fluent采用κ-ε模型对数学模型在稳态运行时的列车外流场流动特性进行数值模拟。将空气阻力系数作为减阻的评定标准,分析了非光滑单元体的形状、间距、直径和深度对减阻性能的影响,为合理设计列车表面的非光滑结构打下基础。最后,本文通过分析摩擦阻力和压差阻力构成及影响因素从不同方面描述了不同非光滑结构对列车外流场的影响。通过分析不同模型的湍动能,及列车表面的压力分布来解释摩擦阻力和压差阻力的成因。通过分析非光滑表面对边界层的影响进一步阐述了非光滑列车表面的减阻机理。更多还原

【Abstract】 As the train speed continuously improves, the interaction between the train and the air is gradually severe. Therefore aerodynamics of train has become a problem that can’ t be neglected by us. When the train is at the speed of 300km/h, the air resistance contains about 85% of the total resistance. Thus, train’ s air resistance is a major component of the total train resistance. Generally speaking, the air resistance of train is closely related to its shape and the proportion of it in the total resistance is also growing as the running speed increases. For this reason, the scientific community and industry focus on research and improve the aerodynamic characteristics of high-speed trains, reducing the aerodynamic drag of the high-speed trains to improve the energy utilization.Takes the maturing high-speed rail technology as research background the CHR2 high-speed train as research object, this paper applies non-smooth surface to the train’s surface based on the research progress of non-smooth surface drag reduction and numerical simulation of the train in order to achieve better drag reduction effect.The models with 36 different kinds of non-smooth surfaces built using UG are divided into unstructured grids by using Hypermesh and ICEM CFD. Then, numerical simulation of flow characteristics of train’ s external flow field is done when the mathematical model is at its steady state through Fluent. Also, this paper considers air drag coefficient as the assessment standard to the drag effects, analyses the impact of the non- smooth unit shape, spacing, diameter and depth of the drag reduction performance on reducing effects so as to smooth unit shape lay the foundation for the rational design of train surface of the non-smooth structure.Finally, this paper describes the effects of non-smooth surface on train’ s external flowing field from different aspects by analyzing the composition of frictional resistance and pressure resistance. The causes of friction and pressure drag are explained by analyzing turbulent kinetic energy of different models and the pressure distribution of train’ s surface. Besides, the drag reduction mechanism of non-smooth surface is further elaborated by studying non-smooth surface’ s impact on boundary layer.更多还原