高速列车进入隧道产生压缩波的实验研究

高速列车进出隧道时会产生一系列空气动力学效应,引起噪声及车厢内压力的变化.实验测试是研究这一问题的有效方法之一.利用高速列车空气动力学模型实验系统对高速列车在进入隧道过程中瞬变压力的传播规律进行研究,并分析了列车速度以及阻塞比对测试结果的影响,得出的结论对以后的研究具有一定的参考和借鉴.     

基于CPS的气动试验研究体系全链路数据融合研究

三大手段融合气动试验是新一代航空航天飞行器研制的必然需求,当前由于链路不通、设备数字化程度低等多种因素,制约了三大手段的有效融合应用。文章分析了气动试验研究体系中的信息物理系统内涵和建设必要性,阐述了信息物理系统与气动试验研究融合的目标愿景,通过构建气动试验研究体系信息物理系统,提出打通数据、流程、试验手段三个链路的方法,形成气动设备、试验研究对象（型号、标模）和人三个维度的数字化,通过气动试验研究大数据为三大手段融合注入新的驱动力,促进气动试验研究能力从数据组织、信息价值、管理能力三个维度螺旋提升,有力推动气动试验研究体系的建立。     

Generation and Visual Exploration of Medical Flow Data: Survey,Research Trends and Future Challenges

Simulations and measurements of blood and airflow inside the human circulatory and respiratory system play an increasingly important role in personalized medicine for prevention, diagnosis and treatment of diseases. This survey focuses on three main application areas. (1) Computational fluid dynamics (CFD) simulations of blood flow in cerebral aneurysms assist in predicting the outcome of this pathologic process and of therapeutic interventions. (2) CFD simulations of nasal airflow allow for investigating the effects of obstructions and deformities and provide therapy decision support. (3) 4D phase‐contrast (4D PC) magnetic resonance imaging of aortic haemodynamics supports the diagnosis of various vascular and valve pathologies as well as their treatment. An investigation of the complex and often dynamic simulation and measurement data requires the coupling of sophisticated visualization, interaction and data analysis techniques. In this paper, we survey the large body of work that has been conducted within this realm. We extend previous surveys by incorporating nasal airflow, addressing the joint investigation of blood flow and vessel wall properties and providing a more fine‐granular taxonomy of the existing techniques. From the survey, we extract major research trends and identify open problems and future challenges. The survey is intended for researchers interested in medical flow but also more general, in the combined visualization of physiology and anatomy, the extraction of features from flow field data and feature‐based visualization, the visual comparison of different simulation results and the interactive visual analysis of the flow field and derived characteristics.     

基于变可信度模型差值的低可信度模型修正方法

为了解决优化设计中计算效率与高可信度信息获取之间的矛盾,从高、低可信度模型的物理机理出发,基于Kriging模型和拉丁超立方设计选样方法构造两模型差值的代理模型;并利用该代理模型对低可信度模型进行修正,构成了具有高可信度的修正模型.与直接对高可信度模型构造的代理模型相比,修正模型不但分析精度更高,而且所需的构造样本更小.文中分别以翼型气动力分析、机翼气动力分析和无人机隐身特性分析为例,从不同维数、不同学科的角度验证了修正模型特性,并进行了机理分析.     

风轮机的风能转换及空气动力学分析

基于流管概念,分析不考虑风轮机叶片旋转等因素时理想情况下风轮机的功率输出及最大风能利用系数．从角动量守恒的角度出发,分析考虑风轮机叶片旋转及由此产生的旋转尾波情况下水平轴风轮机的功率输出．借助于飞机机翼升力概念及叶片元理论,分析水平轴风轮机叶片元的空气动力,指出了风轮机叶片空气动力分析与飞机机翼空气动力分析的差异。     

Digital Flight: The Last CFD Aeronautical Grand Challenge

A case is made for a computational fluid dynamics (CFD) effort to predict aircraft flight characteristics, with a focus on stability and control. Problems in predicting stability and control are discussed. The state-of-the-art in CFD, as it relates to aircraft flight predictions, is reviewed. Problems affecting grid convergence studies are analyzed. The computer resources needed to address flight simulation problems are estimated. The status of critical technologies is briefly discussed.This paper is dedicated to my dear friend David Gottlieb on the occasion of his 60th birthday.     

Experimental study of the effect of turbulence on horizontal axis wind turbine aerodynamics

Incident flows on wind turbines are often highly turbulent, because these devices operate in the atmospheric boundary layer and often in the wake of other wind turbines. This article presents experimental investigations of the effects of a high turbulence level on wind turbine aerodynamics. Power and thrust are measured on a horizontal axis wind turbine model in the ‘Lucien Malavard’ wind tunnel. A grid is used to generate three turbulence levels (4·4%, 9% and 12%) with integral length scale of the order of magnitude of the chord length. Experiments show little effect of turbulence on the wind turbine model power and thrust. This can be justified by analysis of the aerodynamic loads along the blade. Copyright © 2005 John Wiley & Sons, Ltd.     

Polynomial approximation of aerodynamic coefficients based on the statistical description of the wind incidence

In civil engineering applications, the aerodynamic coefficients are usually measured in wind tunnels for several wind incidences. The measurement results need to be linearized in order to perform the design of the structure. This paper justifies the use of different linearization techniques for different assessments as divergence or buffeting analysis. In this latter context, it is proposed to linearize the aerodynamic coefficient by the least-square method, using the probability density function of the wind incidence as a weighting function. First this probability density function is computed for a 2-D wind flow, as a function of the wind intensities and their correlation. Then, the comparison of results from different linearization techniques provides surprising results indicating that what is usually performed should be considered with care.     

Beyond robins: aerodynamic analyses of animal flight

Recent progress in studies of animal flight mechanics is reviewed. A range of birds, and now bats, has been studied in wind tunnel facilities, revealing an array of wake patterns caused by the beating wings and also by the drag on the body. Nevertheless, the quantitative analysis of these complex wake structures shows a degree of similarity among all the different wake patterns and a close agreement with standard quasi-steady aerodynamic models and predictions. At the same time, new data on the flow over a bat wing in mid-downstroke show that, at least in this case, such simplifications cannot be useful in describing in detail either the wing properties or control prospects. The reasons for these apparently divergent results are discussed and prospects for future advances are considered.     

Magnus Force of Common Projectile Bodies with Turbulent Layers

Calculating formulae of Magnus force on common projectile bodies (cone-shaped and parabola-shaped) with turbulent layers were built based on Magnus theory. The effects of temperature exponential were considered, and curve-fitting approaches were adopted in the research that could give more exact result data. Both flow layer constants and shape constants are presented in Magnus force formulae, which are useful to evaluate Magnus force in different states.