旋转流场下模型大幅俯仰运动实验研究

在中航气动院FL-8低速风洞中,采用单自由度振荡机构进行了旋转流场下大幅俯仰运动的气动特性实验研究。模型在绕风速轴连续旋转的同时,进行给定频率和振幅绕体轴的俯仰振荡运动。测量了模型的动态气动特性,着重分析了不同运动参数对模型气动特性的影响。实验结果表明,旋转速度的存在使大振幅俯仰振荡实验中的滚转力矩和偏航力矩产生了明显的迟滞特性,但对俯仰力矩和法向力的迟滞特性影响不大。     

一种超声速气动发电机实验装置及实验技术研究

在对超声速榴弹炮以及导弹引信供电系统的发电机研究中,过去常在闭口式风洞进行实验,但由于闭口式风洞中各种相似参数和特有的因素影响,使得实验数据与真实飞行数据完全不符。因此,多年来只得靠实弹打靶来完善设计方案。本文利用气体动力学和实验空气动力学理论,设计了一种适合气动发电机的超声速试验射流装置,并通过试验详细地研究了装置在出口的流场品质和不同几何外形气动发电机的转速特性,给出了合理的模型试验区、喷管出口流速的确定方法和射流实验区参考压力的选取方法,最后对模型实验结果与打靶遥测数据进行了对照。研究表明,利用超声速射流的工作原理进行导弹引信发电机的模拟实验是可行的,并且该装置可用于引信产品验收。     

飞行器变后掠过程非定常气动特性形成机理

可变体飞行器变后掠过程中的时变气动力与力矩特性对于飞行安全具有重要意义,是亟待深入研究的基础问题.通过风洞实验对其开展了研究,揭示了可变体飞行器变后掠引起的气动特性动态迟滞现象及滞回环大小与方向的影响因素.基于风洞实验结果和力学中一些重要概念,提出了3种物理效应:流场迟滞效应、附加运动效应、固壁牵连效应,以此定性与定量论证了可变体飞行器变后掠过程中非定常气动特性的形成机理.除了能解释实验现象,这一机理研究亦可用于后续可变体飞行器变后掠过程中的气动特性建模.     

飞机大迎角俯仰运动下的横侧向气动特性及被动控制

在南航3m低速风洞内,利用一套两自由度动态试验机构,通过测力实验研究了某飞机模型静态和俯仰动态过程中大迎角下的横侧向气动特性,分析比较了在模型头部加上扰动片后,对横侧向气动特性产生的影响.研究结果表明,模型在静态大迎角下会产生较大的侧向力和偏航力矩,而模型的快速上仰过程则进一步加剧了模型头部流动的非对称性,在大迎角下产生较大的偏航力矩迟滞环;当在模型头部加扰动片后,不论是静态过程还是动态过程,都使得模型的侧向力和偏航力矩减小,从而改善了俯仰运动过程中大迎角下的横侧向气动特性.     

双鸭式气动外形布局的特点

双鸭式气动布局是空-空导弹最近发展的一种新型布局.法国新研制成功的近距格斗型空-空导弹--玛特拉·R550就采用了这种气动布局.本文从前翼与鸭翼相互干扰的基本机理出发,设计鸭翼形状,以期获得较大的增升效果.风洞实验数据证实了 ...     

覆冰四分裂导线动态气动系数风洞试验

覆冰导线舞动是由这些导线的气动不稳定性引起的。由于导线动态空气动力特性不同于静态气动系数,本文针对新月形冰形制作了覆冰四分裂导线模型,通过风洞试验动态测试的装置设定可测量不同扭转频率下的空气动力系数。风洞试验得到了不同扭转运动频率、风速和覆冰厚度等关键工况下新月形覆冰四分裂导线的动态空气动力系数。风洞试验结果显示,动态气动系数与静态气动系数存在显著差异。不同于静态气动系数,动态气动系数曲线是环形的,多种参数对气动系数影响明显。结果表明,风洞试验结果为覆冰分裂导线运动研究及其防治技术提供了必要的数据。     

超临界翼型跨音速特性实验研究

针对新设计的超临界翼型,采用风洞实验方法验证和评估了其气动特性。在增压连续式跨音速风洞(NF-6风洞)开展了超临界翼型跨音速特性的实验研究,验证了该翼型设计的压力分布曲线特点。激波位置和波后压力平台区长度表明设计结果和实验结果基本一致,揭示了超临界翼型跨音速的气动特性;阻力发散马赫数达到期望的设计指标,探讨了雷诺数对该翼型气动特性的影响。最后采用升华法实现了翼型表面流动特性的显示。结果表明转捩点约在16%弦长位置。     

风力机叶片的三维非定常气动特性估算

结合动量-叶素理论、非定常空气动力和动态失速模型来计算风力机叶片的二维非定常气动特性,并在此基础上经过适当修正后考虑三维旋转效应的非定常气动特性。分析比较二维和三维两种计算结果,给出更为合理的计算叶片非定常气动特性的方法。计算结果表明,风力机叶片的三维非定常气动特性计算结果与二维时的计算结果相比有较大改善。     

导弹纵向俯仰气动特性数值分析

应用有限体积方法求解三维可压缩雷诺平均N-S方程,计算了某型巡航导弹的静、动态绕流流场和空气动力特性.湍流模型应用修正后的B-L代数湍流模型.以细长旋成体绕流流场为例进行数值计算,并和实验数据相比较,验证了本文方法的可靠性,在此基础上,开展了某型巡航导弹绕不同转轴和以不同频率进行俯仰振动的非定常气动力迟滞特性研究.计算结果表明,当导弹作快速俯仰振动时,在上仰和下俯过程中的同一迎角瞬间,绕导弹流场流动明显不同,表现出明显的非定常迟滞特性.并且,导弹的非定常气动力迟滞特性随振动频率的增大变化明显,且气动力迟滞曲线随着振动轴位置的变化而变化.     

基于空中发射的运载火箭气动特性实验研究

为了研究空中发射运载火箭的气动特性,本文针对15°半顶角的圆锥-圆柱组合体火箭模型,在1.2m×1m的低速风洞进行实验研究。利用六分量天平测量0°α80°、60m/s以下8个速度的力和力矩特性,基于圆锥底部的雷诺数范围由0.129×106到0.456×106。实验结果显示,随着迎角的增加,火箭流场经历了附体流动、对称旋涡、非对称旋涡到类卡门涡街的变化历程,旋涡的变化决定了火箭的气动特性。特别是30°α70°的大迎角区域,侧力受雷诺数的影响明显,反映了雷诺数变化对火箭流场亚临界区域和临界区域的影响规律。为提高火箭纵向稳定性和姿态的调整,设计了收敛-扩张形尾部并进行了实验验证。研究结果可为空射火箭的外形设计和稳定性分析奠定一定的理论基础。     

The 7th International Conference on Fluid Mechanics May 24-27,2015,Qingdao,China

正http://www.icfm7.org First Announcement and Call for PapersThe objective of International Conference on Fluid Mechanics(ICFM)is to provide a forum for researchers to exchange new ideas and recent advances in the fields of theoretical,experimental,computational Fluid Mechanics as well as interdisciplinary subjects.It was successfully convened by the Chinese Society of Theoretical and Applied Mechanics(CSTAM)in Beijing(1987,     

INFORMATION FOR CONTRIBUTORS

Contributions： The Journal, Acta Mechanica Solida Sinica, is pleased to receive papers from engineers and scientists working in various aspects of solid mechanics. All contributions are subject to critical review prior to acceptance and publication.     

Preface

This special issue of PARTICUOLOGY is devoted to the first UK-China Particle Technology Forum taking place in Leeds, UK, on 1-3 April 2007. The forum was initiated by a number of UK and Chinese leading academics and organised by the University of Leeds in collaboration with Chinese Society of Particuology, Particle Technology Subject Group （PTSG） of the Institution of Chemical Engineers （IChemE）, Particle Characterisation Interest Group （PCIG） of the Royal Society of Chemistry （RSC） and International Fine Particle Research Institute （IFPRI）. The forum was supported financially by the Engineering and Physics Sciences Research Council （EPSRC） of United Kingdom,     

基于鲁棒滤波的捷联导引头视线角速度估计方法

针对捷联导引头无法直接获取视线角速度等信息的问题,研究了鲁棒滤波在大气层外飞行器捷联导引头视线角速度估计中的应用。为了建立非线性滤波估计模型,考虑目标视线角速度的慢变特性,采用一阶马尔科夫模型建立了状态方程;推导了视线角速度的解耦模型,并建立了量测方程;考虑到实际应用中存在系统噪声统计特性失准的问题,基于Huber-Based鲁棒滤波方法,设计了视线角速度滤波器,并完成了基于Huber-Based滤波方法和扩展卡尔曼滤波方法的数学仿真。仿真结果表明Huber-Based滤波方法的视线角、视线角速度及视线角加速度估计精度分别达到0.1140'、0.1423'/s、0.0203'/s2,而扩展卡尔曼滤波方法的视线角、视线角速度及视线角加速度估计精度仅分别为0.6577'、0.6415'/s、0.0979'/s~2。仿真结果证明了该方法可以有效地估计出相对视线角速度等信息,并且在非高斯噪声的条件下,依然可获得较高的估计精度,具有一定的鲁棒性。     

Guide for authors

正Each of the sections below provides essential information for authors.We recommend that you take the time to read them before submitting a contribution to Acta Mechanica Sinica.We hope our guide to authors may help you navigate to the appropriate section.How to prepare a submission This document provides an outline of the editorial process involved in publishing a scientific paper in Acta Mechanica     

Use specification of multiscale materials for life spanned over macro-, micro-, nano-, and pico-scale

Multiscale material intends to enhance the strength and life of mechanical systems by matching the transmitted spatiotemporal energy distribution to the constituents at the different scale, say—macro, micro, nano, and pico,—, depending on the needs. Lower scale entities are, particularly, critical to small size systems. Large structures are less sensitive to microscopic effects. Scale shifting laws will be developed for relating test data from nano-, micro-, and macro-specimens. The benefit of reinforcement at the lower scale constituents needs to be justified at the macroscopic scale. Filling the void and space in regions of high energy density is considered.Material inhomogeneity interacts with specimen size. Their combined effect is non-equilibrium. Energy exchange between the environment and specimen becomes increasingly more significant as the specimen size is reduced. Perturbation of the operational conditions can further aggravate the situation. Scale transitional functions and/or f_j/j+1 are introduced to quantify these characteristics. They are represented, respectively, by , and (f_mi/ma,f_na/mi,f_pi/na). The abbreviations pi, na, mi, and ma refer to pico, nano, micro and macro.Local damage is assumed to initiate at a small scale, grows to a larger scale, and terminate at an even larger scale. The mechanism of energy absorption and dissipation will be introduced to develop a consistent book keeping system. Compaction of mass density for constituents of size 10⁻¹², 10⁻⁹, 10⁻⁶, 10⁻³ m, will be considered. Energy dissipation at all scales must be accounted for. Dissipations at the smaller scale must not only be included but they must abide by the same physical and mathematical interpretation, in order to avoid inconsistencies when making connections with those at the larger scale where dissipations are eminent.Three fundamental Problems I, II, and III are stated. They correspond to the commonly used service conditions. Reference is made to a Representative Tip (RT), the location where energy absorption and dissipation takes place. The RT can be a crack tip or a particle. At the larger size scales, RT can refer to a region. Scale shifting of results from the very small to the very large is needed to identify the benefit of using multiscale materials.