利用旋翼机和固定翼飞机的空气动力学理论综合估算电动垂直起降飞行器的飞行性能

根据旋翼机和固定翼飞机的气动理论开发了一个综合方法过程用于估算电动垂直起降(Electric vertical takeoff and landing, e VTOL)飞行器的飞行性能。这种飞机通常采用多旋翼垂直飞行,螺旋桨和机翼的不同组合方式实现飞行。其中,对旋翼和螺旋桨的气动性能采用传统动量理论分析和旋翼元素分析。本文利用此综合理论研究了12架e VTOL飞行器的飞行性能,包括多旋翼飞行器、矢量推进飞行器和升力巡航飞行器。计算了悬停、爬升和下降以及巡航水平飞行,不同飞行状态时驱动电机、旋翼和机身的飞行特性。据此,可以进一步确定电力推进系统的性能指标,以匹配螺旋桨或旋翼,从而满足飞行任务。

气动技术的理论与实践课程体系改革与实践

气动技术的广泛应用促使高等教育需要培养更多合格的气动技术人才。在培养技术人才的过程中,气动技术的教学、实践与真正的工程项目需求存在差距,因此本文依据工程项目训练方法,结合气动技术的理论与实践课程的改革与实践,在对学生的气动技术知识的传授和实践工程应用能力的锻炼方面,力争纠正目前教学实践中遇到的问题,并采用先进有效的课程评价标准,锻炼学生的认知能力、动手能力和发现问题解决问题的能力,启发学生的创新精神,使学生在整体上把握现代气动技术的工程实践能力,成为优秀的气动理论与工程技术人员。

基于气动人工肌肉理论的半主动空气悬架研究

以改善空气悬架动态性能为目标,提出一种基于气动人工肌肉理论的空气悬架系统。在建立二自由度车辆悬架系统模型、空气弹簧模型、气动人工肌肉动态模型以及迟滞特性数学模型的基础上,依据气动人工肌肉理论的执行器动态特性,设计模糊PID控制策略。对不同路面的仿真结果表明:与被动悬架相比,采用模糊PID控制的空气悬架动态特性有一定改善;对于基于气动人工肌肉理论的模糊PID控制的空气悬架,车身垂向加速度和车轮动载荷均方根值分别降低72%和41%,两指标的功率谱密度在人体敏感频率区域得到明显改善。仿真实验验证了采用基于气动人工肌肉理论的空气悬架系统对车辆行驶平顺性改善的可行性。

栅格翼和机身组合体的气动特性计算与分析

给出计算栅格翼和机身组合体亚超音速气动力干扰理论方法 .亚音速采用涡格法计算栅格翼气动力 ,用一个二维偶极子和圆柱映像涡系模拟机身的上洗流场和栅格翼迁移到机身上气动载荷 .超音速假定栅格翼处在机身横向流动的上洗流场中 ,用翼片理论计算机身对栅格翼气动力干扰的修正因子 .用本文方法计算了几个栅格翼和机身组合体的气动特性的到了比较满意的结果 .

李林塔尔牺牲百年志

李林塔尔是航空发展史的重要人物。他的滑翔飞行对欧洲航空事业产生了巨大影响。也正是李林塔尔的牺牲,促使美国的莱特兄弟投身飞机发展事业,并最终研制成功第一架动力飞机。今年是李林塔尔牺牲100周年,在这100年中,航空技术取得了巨大成就。 在19世纪的飞机发展中,探索动力飞行的人很多。总的说来,动力飞行的探索音往往表现出急于求成、轻视理论、不注重吸收前人成果的特征。这些特征注定了他们少成功而多失败的命运。19世纪飞机发明的时机还不够成熟,由于已经出现的汽油内燃机还需要进一步完善和轻小型化,才使19世纪的航空研究放在气动理论研究和进行滑翔机试验上。

风机降噪研究的现状与分析

综述了近年来有关风机噪声的一些研究状况 ,包括已取得的成绩和面临的一些问题 ,对风机噪声的控制方法进行了大致的分类介绍 ,对新的发展趋势和应进一步深入研究的问题进行了探讨。

麦克斯韦与物理学的发展

本文主要从电磁场理论和气动理论两个方面阐述了麦克斯韦对物理学发展所做出的巨大贡献。

某型发动机动态特性仿真研究

根据气动热力学理论 ,考虑转子惯性和容积特性的影响 ,在发动机稳态模型的基础上 ,建立了某型发动机的动态模型 ,并利用C语言编制了相应的仿真程序。仿真结果与实际物理过程相符合 ,证明了模型和程序的正确性 。

MULTI-OBJECTIVE SHAPE DESIGN IN AERODYNAMICS USING GAME STRATEGY

Multi-objective optimization for the optimum shape design is introduced in aerodynamics using the Game theory. Based on the control theory, the employed optimizer and the negative feedback are used to implement the constraints. All the constraints are satisfied implicitly and automatically in the design. Furthermore,the above methodology is combined with a formulation derived from the Game theory to treat multi-point airfoil optimization. Airfoil shapes are optimized according to various aerodynamics criteria. In the symmetric Nash game, each “player” is responsible for one criterion, and the Nash equilibrium provides a solution to the multipoint optimization. Design results confirm the efficiency of the method.

钢—混组合梁斜拉桥风致抖振响应分析

文章对某钢-混组合梁斜拉桥进行了风致抖振响应分析。首先通过计算流体力学软件对桥梁进行气动分析得到静力三分力系数,再分析桥址风场资料并根据规范采用风谱,利用谱分解法得到风谱时程,基于准定常气动理论将得到的风谱时程转换为气动力时程。通过编程软件与有限元软件结合来模拟求解桥梁自然紊流风场下的抖振响应。结果表明:桥塔在最大悬臂状态出现最大抖振内力与位移RMS值;梁体在+3°攻角工况下有最大响应,最大悬臂阶段在边跨1/2处有最大位移RMS值,在中跨1/4处截面有最大内力RMS值;成桥阶段在主跨跨中有最大位移RMS值,在塔1处截面有最大内力RMS值;经分析该桥具有良好的抗风性能。

化学激光器

TN248.5 2001042439DF/HF化学激光器喷管设计和数值模拟=Nozzle designand numerical simulation method of nozzle flow in DF/HF chemical lasers[刊,中]/袁圣付,华卫红,姜宗福,赵伊君(国防科技大学应用物理系.湖南,长沙(410073))//中国激光.-2001,28(1).-19-21简述了喷管作用和单个喷管型面设计中存在的问题,根据气动理论提出了一种喷管设计新方法;介绍了DF/HF激光器喷管流动数值模拟的控制方程、初边值条件和CS方法。参12(赵桂云)

直升机旋翼控制技术的研究进展探讨

本文从空气动力学的角度分析了直升机旋翼的控制原理,然后利用CFD法中的欧拉方程对直升机旋翼控制流场计算方法做了研究,最后对直升机旋翼的可靠度分析方法做了简要的探讨。

Wind-induced responses of super-large cooling towers

Traditional gust load factor(GLF)method,inertial wind load(IWL)method and tri-component method(LRC+IWL)cannot accurately analyze the wind-induced responses of super-large cooling towers,so the real combination formulas of fluctuating wind-induced responses and equivalent static wind loads(ESWLSs)were derived based on structural dynamics and random vibration theory.The consistent coupled method(CCM)was presented to compensate the coupled term between background and resonant response.Taking the super-large cooling tower(H=215 m)of nuclear power plant in Jiangxi Province,China,which is the highest and largest in China,as the example,based on modified equivalent beam-net design method,the aero-elastic model for simultaneous pressure and vibration measurement of super-large cooling tower is firstly carried out.Then,combining wind tunnel test and CCM,the effects of self-excited force on the surface pressures and wind-induced responses are discussed,and the wind-induced response characteristics of background component,resonant component,coupled term between background and resonant response,fluctuating responses,and wind vibration coefficients are discussed.It can be concluded that wind-induced response mechanism must be understood to direct the wind resistant design for super-large cooling towers.

D1250鼓风机扩容改造

介绍了用三元流技术改造风机的情况，既满足了生产要求，又节约了资金。

Modeling the pressure drop of wet gas in horizontal pipe

A model for gas–liquid annular and stratified flow through a horizontal pipe is investigated, using the two-phase hydrokinetics theory. Taking into consideration the flow factors including the void fraction, the friction between the two phases and the entrainment in the gas core, the one-dimensional momentum equation for gas has been solved. The differential pressure of the wet gas between the two tapings in the straight pipe has been modeled in the pressure range of 0.1–0.8 MPa. In addition a more objective iteration approach to determine the local void fraction is proposed. Compared with the experimental data, more than 83% deviation of the test data distributed evenly within the band of ± 10%. Since the model is less dependent on the specific empirical apparatus and data,it forms the foundation for further establishing a flow measurement model of wet gas which will produce fewer biases in results when it is extrapolated.

Dispersion Relations in Binary Gas Mixtures From a Kinetic Theory

Sound propagation and the initial value problems in gas mixtures of two components are investigated. By using the eigen theory of linearized Boltzmann equations, a model equations is formed, with the use of the Fourier-Laplace transform for model equations derived, the dispersion relations for both components are obtained.

Study of modeling theory of multiphase gas distribution in exhaust process of automobile

According to experiments and the phenomena that tailpipes often have dirty particulate matter, this paper takes dynamic theory analysis as its study aim, beginning with the description method of multiphase gas distribution differential equation. According to the characteristics that exhaust gas will flow with high velocity in a tailpipe, it is supposed that gas mass that differ largely will layer when flowing with high velocity in a tailpipe. This means the exhaust gas is mixed with particulate matter, gas with large mass （CO2,HC,NOx） and gas with small mass （CO,H2O,N2,O2）. The interface of two phase fluid will be become clearer as it flows in the pipe for a long distance. The fluid continuous equation between gas phase and solid phase and the mathematical relationship between the geometry parameter and the flowing are established by a multiphase gas flowing theory. Analyzing the interface and state of layers will provide a basic theory for developing a catalytic converter with high efficiency.

HP nonlinear guidance law design based on smooth sliding mode control

To eliminate the perturbation of interceptor detection induced by aerodynamic heating,the head pursuit (HP) guidance law for three-dimensional interception was presented. The guidance law positioned the interceptor ahead of the target on its flight trajectory,and the speed of interceptor was required to be lower than that of the target. On the basis of a novel head pursuit three-dimensional guidance model,a nonlinear guidance law was developed based on smooth sliding mode control theory. At the same time,a special observer was designed to estimate the target acceleration,and a numerical example on maneuvering ballistic target interception verified the effectiveness of the presented guidance law.

A Review of the Nonlinear Dynamics of Intraseasonal Oscillations

In recent years,significant progress has been made regarding theories of intraseasonal oscillations (ISOs) (also known as the Madden-Julian oscillation (MJO) in the tropics).This short review introduces the latest advances in ISO theories with an emphasis particularly on theoretical paradigms involving nonlinear dynamics in the following aspects:(1) the basic ideas and limitations of the previous and current theories and hypotheses regarding the MJO,(2) the new multi-scale theory of the MJO based on the intraseasonal planetary equatorial synoptic dynamics (IPESD) framework,and (3) nonlinear dynamics of ISOs in the extratropics based on the resonant triads of Rossby-Haurwitz waves.

Boltzmann方程碰撞积分建模与稀薄空气动力学应用研究

直接模拟蒙特卡罗方法(Direct Simulation Monte Carlo,DSMC)已经广泛用于稀薄空气动力学计算模拟,而直接数值求解Boltzmann方程目前还只局限于简单流动,比如一维线性问题.高度非线性、积分微分属性的Boltzmann方程的求解关键是碰撞积分建模问题.最近,快速谱方法的提出和完善,使得对复杂的三维非线性问题直接求解Boltzmann方程带来了希望.相对于DSMC,快速谱方法具有数值上确定性的优势,在低速多尺度流动计算模拟上更为高效.本文介绍了快速谱方法在求解气体动理学方程的最新发展和成果,并探讨其应用前景.快速谱方法的推广应用使之真正成为DSMC的补充方法,现在面临的困难是需要发展新的气体动理学模型来描述多原子、多组分、稠密气体等.本文最后介绍了这方面的最新进展和直接求解Boltzmann模型方程气体动理论统一算法在模拟计算跨流域气体绕流及航天再入高超声速气动问题的应用.