汽车水平外形参数对气动阻力影响的仿真分析

针对现有的汽车气动性能优化研究大多集中于纵向外形参数上,缺乏对水平外形参数研究的问题,选取水平外形参数中车尾收缩角和后风窗收缩角作为气动优化研究对象.利用数值仿真软件建立车体模型并进行仿真,求解获得水平外形参数的变化对气动阻力的影响规律.将水平参数的变化与对应的纵向外形参数的减阻效果进行对比分析.结果表明：水平外形参数的变化引起尾流结构显著变化,且与对应的纵向外形参数相比其减阻效果更好.因此,水平外形参数对汽车气动性能优化具有积极影响.     

Teaching aerodynamics using a microcomputer

An interactive and wholly automatized computer code has been developed on a microcomputer for the aerodynamic analysis of airfoils in incompressible now fields. It is intended to serve as a useful support in teaching aerodynamics. The code contains a number of modules (or blocks) for: (1) drawing the shape with the help of an interactive graphic device interfaced with the microcomputer; (2) computing the aerodynamic inviscid and viscous flow field and the aerodynamic coefficients; (3) modifying and/or correcting the body shape and then computing the new aerodynamic coefficients. In this way the student can evaluate, operating directly and interactively, the influence of the changes in shape on the aerodynamics of the airfoil under study.     

3D imaging application in the studies of micro air vehicles

3D techniques are increasingly used in aerospace industry to improve quality and performance of aircrafts. This paper presents a 3D imaging technique for studying the aerodynamic shape and flight performance of micro air vehicles. 3D stereoscopic vision, based upon stroboscopic imaging, was utilized to obtain the 3D information of the aircraft's flexible aerodynamic surface. The aircraft models with deformable aerodynamic shape were designed and tested in a purpose-built wind tunnel experimental environment. After calculation of SIFT feature points and subdivision of triangular meshes, deformable surface of the aircraft's aerodynamic shape was represented. The aircraft's 3D visualization was used for analyzing unsteady deformation in the aerodynamic shape under external airflow disturbances. The results, together with aerodynamic forces measured in the experiment, will be useful to improve the flight performance and disturbance resistance ability of micro air vehicles.     

基于NURBS方法的气动外形优化设计

采用NURBS曲线曲面,对钝锥弹头和钝双锥弹体建立参数化曲面模型,取NURBS曲线控制点作为设计参数,应用高超声速面元法求解气动力特性,在给定设计约束下,采用遗传算法进行气动外形优化设计,并对优化结果进行了比较分析。结果表明,采用NURBS方法构造参数化外形,并结合优化技术可方便快速地获得所需最优外形;与应用二次曲线构造参数化外形相比,该方法对弹体形状控制更加灵活,并可局部修改弹头曲线形状。因此,基于NURBS方法发展整套的系统优化设计算法很有现实意义和应用价值。     

机翼气动结构耦合数值分析方法

针对机翼的静气动弹性问题,为准确预测其气动特性,研究一种实用有效的气动结构耦合仿真方法.以客机机翼设计为例,通过机翼的静气动弹性问题分析和机翼的气动结构耦合分析流程的分解,建立参数化、自动化、模块化的气动结构耦合仿真分析平台.该平台的流程包括基于全速势方程的气动分析、基于MSC Nastran的结构仿真、应用MATLAB的载荷到结构模型的传递、结构变形向气动外形的映射等环节.算例表明该方法能较好地解决机翼的静气动弹性分析问题.     

基于近似模型的整车气动外形优化

以类车体DrivAer的气动阻力因数为优化目标,选取影响其气动性能的5个形状参数作为设计变量,通过引入网格变形、试验设计(Design of Experiment,DOE)及近似模型等技术搭建自动仿真优化平台,探索气动性能最佳的参数匹配方案.优化后的DrivAer气动阻力因数降低4.5%,表明近似模型方法能够较好地取代实际仿真过程进行寻优.分析DOE的结果,发现影响气动阻力因数和气动升力因数的主要参数分别为行李箱高度与离去角,而多参数变化时的交互效应也会影响整车的气动性能.     

面向分级设计优化的飞行器参数化建模方法

针对飞行器气动隐身外形综合设计优化问题,提出合适的面向分级设计优化流程,建立适应该流程的渐进分层参数化建模方法;用基于敏度分析的参数影响程度分析方法筛选复杂设计变量;采用多学科设计优化（Multidisplinary Design Optimization,MDO）理论和差分进化算法进行飞行器气动隐身外形的综合设计优化.将该方法用于某飞行器外形设计优化,结果表明：该方法合理可行,可为飞行器外形多学科设计优化提供一定参考.     

基于VB的风力机叶片外形优化设计

为了实现风力发电机风轮叶片外形的优化设计,以风场风速分布为基础提出了综合优化目标;以片条理论为基础提出了以展弦比为关键参数的修形约束条件的气动优化目标,建立了叶片外形优化设计的数学模型。采用枚举法和循环结构,选用Access数据库,应用Visual Basic编制程序实现叶片外形的优化设计。针对内蒙古某地区设计了1.5MW风力机叶片,与国外同功率某通用叶片进行了对比分析。结果表明,两种叶片外形基本吻合,而且文中设计的叶片在性能上有明显优势,同时也验证了文中提出数学模型的可靠性和程序的实用性。     

A surrogate-model based multidisciplinary shape optimization method with application to a 2D subsonic airfoil

A surrogate-model based shape optimization method is presented and applied to the case of the multidisciplinary shape optimization of a 2D NACA subsonic airfoil. The cost function is designed so that both the far-field radiated noise and the aerodynamic forces are controlled. The surrogate model is based on the Kriging optimal interpolation technique. In order to increase the efficiency of the method, a dynamic Kriging method is developed, which can be interpreted as an Adaptive Mesh Refinement method in the shape optimization parameters.     

Condition diagnostics of Russian railways infrastructure constructions under aerodynamic loads from high-speed trains

Aim of the present research is realization of a complex procedure on the basis of the combined approach for modeling aerodynamic loads on elements of the infrastructure (station constructions and designs, pedestrian crossings, bridges and tunnels) at high speed trains passage. Work is devoted to powerful methods of viscous gas currents modeling programs development and realization for research of aerodynamic loads on bodies making various movements, including shape variation, and to problems of bodies movement under aerodynamic forces solution.