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底部导流板形式对高速列车气动阻力的影响 总被引:1,自引:0,他引:1
为减小高速列车运行时的气动阻力,设计直式、斜式、内圆弧式和外圆弧式等4种转向架前后底部导流板的高速列车模型.通过风洞试验验证数值模拟方法的有效性,采用数值计算分析底部导流板对列车气动阻力和底部流场的影响.结果表明:不同形式底部导流板的列车总阻力相差可达20%,其中头车气动阻力因数极差值最大为0.062.导流板影响列车底部气流速度和转向架区域压力分布,其导流作用使得转向架区域气动阻力和转向架的阻力同时改变.转向架前后导流板的导流效果越好,转向架区域的气动阻力越小;同时,气流冲击使得转向架上的滞止压力增大;在二者的共同作用下高速列车的总阻力存在一个较小值.底部采用直式导流板对降低全车气动阻力的效果最好. 相似文献
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某型涡扇发动机涡轮过渡流道与整流支板一体化设计方案中,支板采用了弯掠组合构型方案.为深入理解支板设计机理及其对流道总体性能影响规律,开展了对该型支板反设计研究.以涡轮过渡流道支板的进、出口气动参数和相应的几何参数为输入条件,结合标准支板叶型,应用所开发的叶型造型软件对弯掠支板作了详细反设计及相应的造型计算,获得的支板造型结果与原始结果十分吻合;随后对带支板和下游低压涡轮导向器叶排的整个过渡流道性能进行全三维CFD数值分析.数值计算与对应实验结果一致性较好,一方面表明反设计方法是可行和可靠的;同时表明合理的支板弯掠构型与恰当的流道型面有机组合能明显提高涡轮过渡流道的性能. 相似文献
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为揭示轿车侧窗开启程度和乘员舱内布置对气动阻力的影响规律,建立1∶1阶背式英国汽车研究协会(Motor Industry Research Association,MIRA)标准模型;基于FLUENT,在30 m/s风速下采用可实现k-ε湍流模型对不同侧窗开度的模型进行三维稳态数值模拟,得到气动阻力因数随侧窗开启程度的增大而增大的变化趋势.在侧窗全开时,改变舱内布置,得到气动阻力因数随假人个数的变化规律;对比不同情况下模型的流场分布发现,当考虑乘员舱内气流时,气动阻力的大小不仅与进气量有关,而且受舱内流场分布的影响. 相似文献
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In the early design stage, automotive modeling should both meet the requirements of aesthetics and engineering. Therefore, a vehicle CAD (computer aided design) model that can be easily adjusted by feedbacks is necessary. Based on CE-Bézier surface, this paper presents a set of algorithms for parametric segmentation and fairing surface generation in a car model. This model is defined by a simplified automotive template and relevant control points, shape parameters and segmentation parameters, which can be modified to alter the car form efficiently. With this model and the corresponding adjustment method, more than fifty various vehicle models are established in this research according to different parameters. And two methods for calculating similarity index between car models are constructed, which are suitable for brand design trend analysis and modelling design decisionmaking. 相似文献
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为了改善驾驶员在夜间或能见度较低环境下的视野范围,提高行驶的安全性,介绍了一种基于嵌入式系统的汽车自适应前照灯系统的设计方案。此系统中的前照灯控制器采用FPGA来控制CAN总线控制器、数/模转换器和全桥电机驱动器等器件来实现接收方向盘转角信号,并使电机运行带动前照灯的转向。自适应前照灯系统控制中心使用的是ARM9处理器。该设计方案满足要求,已经在项目中获得了良好的应用效果。 相似文献
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《Ergonomics》2012,55(2):163-181
A brief survey is given of the historical development of motor vehicle headlights. The principles underlying the design of the block lens headlamp used in America and Great Britain and the sharp out-off lens used on the Continent are described and a comparison is made of the two systems. An outline is given of the polarized headlamp system that is being investigated by the Laboratory. 相似文献
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Guangyong Sun Xueguan Song Seokheum Baek Qing Li 《Structural and Multidisciplinary Optimization》2014,49(6):897-913
Deterministic optimization has been successfully applied to a range of design problems involving foam-filled thin-walled structures, and to some extent gained significant confidence for the applications of such structures in automotive, aerospace, transportation and defense industries. However, the conventional deterministic design could become less meaningful or even unacceptable when considering the perturbations of design variables and noises of system parameters. To overcome this drawback, a robust design methodology is presented in this paper to address the effects of parametric uncertainties of foam-filled thin-walled structure on design optimization, in which different sigma criteria are adopted to measure the variations. The Kriging modeling technique is used to construct the corresponding surrogate models of mean and standard deviation for different crashworthiness criteria. A sequential sampling approach is introduced to improve the fitness accuracy of these surrogate models. Finally, a gradient-based sequential quadratic program (SQP) method is employed from 20 different initial points to obtain a quasi-global robust optimum solution. The optimal solutions were verified by using the Monte Carlo simulation. The results show that the presented robust optimization method is fairly effective and efficient, the crashworthiness and robustness of the foam-filled thin-walled structure can be improved significantly. 相似文献
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L. Dai Z. Q. Guan B. S. Chen H. W. Zhang 《Structural and Multidisciplinary Optimization》2008,35(6):609-622
A general platform built on a computer-aided design (CAD) system is developed for parameterized shape design optimization
of shell structure. Within the platform, parameterized surface modeling and computer-aided engineering (CAE) applications
are embedded and seamlessly integrated with the CAD system through its application programming interface (API). Firstly, instead
of the CAD system inherent surface modeling, a parameterized surface modeling for shell structure is fulfilled through integrating
with parametric solid modeling of the CAD system. Thus, any dimensions for parametric solid modeling can be used to control
shape modification of shell structure and serve as design variables for shape design optimization. Secondly, seamless integration
of geometry modeling and finite-element modeling for shell structure is implemented. Finally, with integrated procedures of
finite-element analysis and optimization algorithms, a general platform for parameterized shape optimization of shell structure
is realized. Numerical examples are presented, and the results validate the effectiveness and efficiency of the platform.
A shorten version of this paper was presented to the 7th World Congress of Computation Mechanics (WCCM 2006), July 16–22,
2006, Los Angeles, CA, USA. 相似文献
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在桥梁养护行业,传统桥梁病害检测方式向数字化检测转型已成为该行业发展趋势,而桥梁三维可视化是实现数字化检测的基础.一般的梁式桥参数化建模程序,具有“一经写定,不易修改”的弊端,为了避免这一问题,提高参数化建模的灵活性与可扩充性,采用了一种将专家系统与梁式桥参数化建模相结合的方法,该方法结合专家系统理论知识、梁式桥结构知识和梁式桥组件及全桥参数化建模过程,设计了梁式桥快速建模专家系统.主要内容包括知识库的分类设计、知识库的数据库表设计、知识表达方式的选取、组件建模推理机制及全桥建模推理机制,以及参数化建模时部件、组件、全桥建模算法.使用该方法进行梁式桥建模结果表明,该方法能够根据用户给出的少量主要参数准确完成桥梁组件及全桥的参数化建模,用户通过修改知识库,就能改动参数化建模所依赖的结构计算知识.该方法增加了参数化建模的灵活性及可扩充性. 相似文献