With the continuous improvement of the train speed, the dynamic environment of trains turns out to be aerodynamic domination. Solving the aerodynamic problems has become one of the key factors of the high-speed train ...With the continuous improvement of the train speed, the dynamic environment of trains turns out to be aerodynamic domination. Solving the aerodynamic problems has become one of the key factors of the high-speed train head design. Given that the aerodynamic drag is a significant factor that restrains train speed and energy conservation, reducing the aerodynamic drag is thus an important consideration of the high-speed train head design. However, the reduction of the aerodynamic drag may increase other aerodynamic forces (moments), possibly deteriorating the operational safety of the train. The multi-objective optimization design method of the high-speed train head was proposed in this paper, and the aerodynamic drag and load reduction factor were set to be optimization objectives. The automatic multi-objective optimization design of the high-speed train head can be achieved by integrating a series of procedures into the multi-objective optimization algorithm, such as the establishment of 3D parametric model, the aerodynamic mesh generation, the calculation of the flow field around the train, and the vehicle system dynamics. The correlation between the optimization objectives and optimization variables was analyzed to obtain the most important optimization variables, and a further analysis of the nonlinear relationship between the key optimization variables and the optimization objectives was obtained. After optimization, the aerodynamic drag of optimized train was reduced by up to 4.15%, and the load reduction factor was reduced by up to 1.72%.展开更多
With the increasing demand of higher travelling speed,a new streamlined high-speed maglev train has been designed to reach a speed of 600 km/h.To better capture the flow field structures around the maglev train,an imp...With the increasing demand of higher travelling speed,a new streamlined high-speed maglev train has been designed to reach a speed of 600 km/h.To better capture the flow field structures around the maglev train,an improved delayed detached eddy simulation(IDDES)is adopted to model the turbulence.Results show that the new maglev train has good aerodynamic load performance such as small drag coefficient contributing to energy conservation.The main frequencies of aerodynamic forces for each car have a scattered distribution.There are two pairs of counter-rotating large vortices in the non-streamlined part of the train that make the boundary layer thicker.Many high-intensity vortices are distributed in the narrow space between skirt plates or train floor and track.In the gap between the train floor and track(except near the tail car nose),the main frequency of vortex shedding remains constant and its strength increases exponentially in the streamwise direction.In the wake,the counter-rotating vortices gradually expand and reproduce some small vortices that move downward.The vortex has quite random and complex frequencydomain distribution characteristics in the wake.The maximum time-averaged velocity of the slipstream occurs near the nose of the head car,based on which,the track-side safety domain is divided.展开更多
对比了国内外高速列车车体设计标准中气动载荷的设计要求,分析了明线会车侧墙压力波,采用时间积分法,将车体瞬态压强转化为侧墙气动载荷,参照标准BS EN 12663-1—2010确定了包括气动载荷的车体疲劳载荷工况,以某型动车组头车为研究对象...对比了国内外高速列车车体设计标准中气动载荷的设计要求,分析了明线会车侧墙压力波,采用时间积分法,将车体瞬态压强转化为侧墙气动载荷,参照标准BS EN 12663-1—2010确定了包括气动载荷的车体疲劳载荷工况,以某型动车组头车为研究对象,建立了车体有限元模型,基于车体Goodman疲劳强度曲线编写了车体疲劳强度后处理程序,研究了车体疲劳特性。计算结果表明:在不考虑气动载荷时计算的较大应力幅值出现在底架上,而在考虑气动载荷时计算的车体较大应力幅值出现在侧墙门角和窗角上,最大应力幅值为33.63 MPa,疲劳强度安全系数为2.26,相对于侧墙,底架的应力幅值较小,小于10.00 MPa,疲劳强度安全系数大于10.00。在垂向载荷作用下,侧墙最大当量应力为68.17 MPa,叠加气动载荷后侧墙最大当量应力为85.31 MPa,应力增大了25.14%,因此,气动载荷对侧墙影响较大,容易导致侧墙发生疲劳失效。可见,在高速列车车体设计时,应将气动载荷与其他疲劳载荷相组合对车体疲劳强度进行评定。展开更多
基金Project supported by the National Natural Science Foundation of China (No. 50823004)the National Key Technology R&D Program of China (No. 2009BAG12A01-C09)+1 种基金the 2013 Doctoral Innovation Funds of Southwest Jiaotong Universitythe Fundamental Research Funds for the Central Universities, China
文摘With the continuous improvement of the train speed, the dynamic environment of trains turns out to be aerodynamic domination. Solving the aerodynamic problems has become one of the key factors of the high-speed train head design. Given that the aerodynamic drag is a significant factor that restrains train speed and energy conservation, reducing the aerodynamic drag is thus an important consideration of the high-speed train head design. However, the reduction of the aerodynamic drag may increase other aerodynamic forces (moments), possibly deteriorating the operational safety of the train. The multi-objective optimization design method of the high-speed train head was proposed in this paper, and the aerodynamic drag and load reduction factor were set to be optimization objectives. The automatic multi-objective optimization design of the high-speed train head can be achieved by integrating a series of procedures into the multi-objective optimization algorithm, such as the establishment of 3D parametric model, the aerodynamic mesh generation, the calculation of the flow field around the train, and the vehicle system dynamics. The correlation between the optimization objectives and optimization variables was analyzed to obtain the most important optimization variables, and a further analysis of the nonlinear relationship between the key optimization variables and the optimization objectives was obtained. After optimization, the aerodynamic drag of optimized train was reduced by up to 4.15%, and the load reduction factor was reduced by up to 1.72%.
基金Project supported by the National Natural Science Foundation of China(No.51605397)the National Key R&D Program of China(No.2016YFB1200602-15)the Sichuan Provincial Science and Technology Support Program(No.2019YJ0227),China。
文摘With the increasing demand of higher travelling speed,a new streamlined high-speed maglev train has been designed to reach a speed of 600 km/h.To better capture the flow field structures around the maglev train,an improved delayed detached eddy simulation(IDDES)is adopted to model the turbulence.Results show that the new maglev train has good aerodynamic load performance such as small drag coefficient contributing to energy conservation.The main frequencies of aerodynamic forces for each car have a scattered distribution.There are two pairs of counter-rotating large vortices in the non-streamlined part of the train that make the boundary layer thicker.Many high-intensity vortices are distributed in the narrow space between skirt plates or train floor and track.In the gap between the train floor and track(except near the tail car nose),the main frequency of vortex shedding remains constant and its strength increases exponentially in the streamwise direction.In the wake,the counter-rotating vortices gradually expand and reproduce some small vortices that move downward.The vortex has quite random and complex frequencydomain distribution characteristics in the wake.The maximum time-averaged velocity of the slipstream occurs near the nose of the head car,based on which,the track-side safety domain is divided.
