临近空间浮空器区域驻留控制策略研究

为了实现临近空间浮空器区域驻留飞行,基于对热环境的分析,建立了带有副气囊高空气球的空气动力学与热力学耦合动力学模型。基于准零风层特殊风场,设计了临近空间浮空器区域驻留飞行控制策略,通过副气囊调节飞行高度,利用准零风层上下纬向风方向相反的特点实现东西方向控制,用螺旋桨控制实现南北方向控制,并利用ECMWF风场数据进行了数值仿真。仿真结果表明,临近空间浮空器可以在纬度41°(N)~43°(N),经度86.5°(E)~87.1°(E)之间的区域范围内飞行7天,证明了利用准零风层风场实现临近空间浮空器区域驻留飞行的可行性。     

基于Kriging模型的浮空器氦气昼夜温差最优化

分析浮空器氦气昼夜温差时通常将整个囊体蒙皮涂层设置为同一种材料,分析材料的吸收率与发射率对氦气昼夜温差的影响。为进一步减小氦气昼夜温差,提出了将囊体分为迎光面和背光面,迎光面采用吸收率低的材料,背光面采用发射率高的材料。建立了囊体热力学模型,采用Kriging模型对囊体不同部位的材料特性进行优化,其基本思想是将囊体划分为48个部分,采用拉丁超立方体方法进行抽样,进行热力学分析得到样本的响应,以此建立Kriging近似模型。经过该方法优化后发现,氦气的昼夜温差减小到28.6 K,比传统的分析减少7.7%。      

高空系留气球建模与稳定性分析

平流层高空系留气球是典型的无控制欠阻尼自治系统,因此平台本身应当具有较好的稳定性,然而该系统的线性化模型含有零特征根,导致经典的Lyapunov第一方法难以从理论上获得其稳定性结论.从一般刚体的Newton-Euler方程出发,根据刚体对任一点的平动和转动方程,建立基于广义坐标的高空系留气球二阶非线性动力学模型,并针对Lyapunov方法证明稳定性的局限性,从能量的角度运用拉格朗日定理证明了高空系留气球的稳定性,数值仿真结果与理论结果一致.     

基于刚柔耦合模型的月球着陆器动力学分析

基于刚柔耦合多体动力学理论,提出了一种基于三维实体造型、有限元分析与多体动力学分析的刚柔耦合动力学仿真分析方法;利用该方法建立了月球着陆器着陆动力学模型,分别在地球重力环境和月球重力环境(1/6地球重力环境)下,对某典型着陆工况下的着陆动力学进行了仿真分析,得到了着陆器着陆的缓冲性能分析结果,包括主支柱最大缓冲行程、左右辅助支柱最大缓冲行程、最大质心加速度响应;将仿真结果与试验结果相比较,验证了着陆器动力学模型的正确性以及仿真分析方法的有效性,为今后的着陆器缓冲试验提供了动力学模型和仿真分析方法.从能量角度对月球着陆器的着陆过程进行分析,弥补了缓冲试验难以进行能量分析的不足.     

航空供氧系统高空性能参数数值仿真

根据航空供氧系统高空性能的工作原理,利用理论简化结构模型和气体动力学知识,建立了供氧系统部分高空性能参数的数学模型.在Matlab/Simulink系统仿真环境下,对高空部分性能参数进行了数值仿真计算,分析了高空性能中的充氧时间控制以及供氧面罩余压与拉力管内压力的比值特性和各种结构参数对面罩余压大小的影响.通过对仿真计算结果与试验结果的对比分析,表明所建立的数学模型是有效的,采用的仿真计算方法符合计算精度要求,对供氧系统高空性能的设计和改进工作具有一定的参考作用.     

代偿服加压条件下的血液动力学仿真

利用仿真方法研究飞行员穿着高空代偿服加压条件下生理参数的变化情况,探索加压对人体血液循环功能的影响及其变化规律,为飞行员高空防护提供理论支持.在Heldt立位应激模型的基础上,针对代偿服加压特性进行修正,建立人体加压条件下的血液动力学模型,同时通过地面加压试验验证模型的正确性.模型模拟得到全身侧管式代偿服不同加压条件下的血液动力学参数平均动脉压、每搏量和每分量,并与试验值进行对比,模型结果与试验值吻合较好,验证了模型的有效性.模型可有效地模拟代偿服加压条件下的血液动力学变化情况.     

月球软着陆动力学分析与仿真

以4腿式月球探测器为研究对象,分析了探测器的部件结构与物理属性、月球物理环境等综合因素.在探测器动力学研究中,提出了一种基于结构的分块参数化仿真方法,分析探测器着陆时的受力,建立着陆腿与足垫等关键部件的动力学模型,利用简化探测器结构,综合各部分模型.结合虚拟现实可视化仿真技术,实现月球软着陆过程仿真.通过仿真反映出月面坡度与着陆速度、刚度系数与阻尼系数等初始条件对软着陆效果的影响,验证方法的有效性.该方法已成功应用于登月工程研究.     

大型客机驾驶舱气流热仿真及舒适性评价

驾驶舱的空气速度场和温度场直接影响驾驶员的热舒适和工效,是驾驶舱结构和环境控制系统设计中考虑的重要内容.对B737-800驾驶舱进行全尺寸三维建模,以高空夜航工作情况为例,采用商用CFD(Computational Fluid Dynamics)软件Fluent计算该驾驶舱的流场和温度场,再用平均温度评价指标和热环境综合评价指标PMV(Predicted Mean Vote)来对驾驶舱进行温度环境客观评价,并采用问卷调查法对飞行员进行驾驶舱内部空气流速和温度舒适度的主观评价.数值仿真结果与主观评价结果都得出B737-800驾驶舱在高空夜航时基本处于舒适的环境,除躯干和脚部由于偏凉而略感不舒适.数值仿真结果与客观评价结果的一致性,验证了大型客机驾驶舱气流热仿真的准确性.     

某系留气球抗风性能仿真分析

系留气球以其显著特点已应用到许多领域,今后还会有大的发展。因所处环境的风力对飞行稳定性影响较大,故抗风能力成为系统重要指标。针对无法用实验手段进行验证的空中工作姿态,一般采取计算机仿真方法进行模拟研究。介绍了系留气球的设备组成,描述了空中飞行状态,通过建立动力学模型的数学方程式,施加1-consine型离散突风模型扰动,仿真了空中球体的俯仰角和滚转角随扰动时间的关系曲线,并对结果曲线进行分析研究,以期为同型系留气球的设计方法提供某种借鉴,为浮空器使用安全提供帮助。     

A comprehensive numerical model investigating the thermal-dynamic performance of scientific balloon

The increase of balloon applications makes it necessary for a comprehensive understanding of the thermal and dynamic performance of scientific balloons. This paper proposed a novel numerical model to investigate the thermal and dynamic characteristics of scientific balloon in both ascending and floating conditions. The novel model consists of a dynamic model and thermal model, the dynamic model was solved numerically by a computer program developed with Matlab/Simulink to calculate the velocity and trajectory, the thermal model was solved by the Fluent program to find out the balloon film temperature distribution and inner Helium gas velocity and temperature field. These models were verified by comparing the numerical results with experimental data. Then the thermal and dynamic behavior of a scientific balloon in a real environment were simulated and discussed in details.     

双层乳胶气球的高空平漂机理及垂直轨迹模拟

双层乳胶气球克服了单层乳胶气球的缺点,可以在高空平漂以实现持续气象观测,但是其高空平漂受多因素影响比较复杂,特别是气球充气量主要依赖工程经验,施放成功率不高,亟需提供理论指导。通过试验数据证明了浮重平衡是双层乳胶气球实现高空平漂的必要条件,推导得出内、外球氢气充气量和昼夜温度变化对其运动的影响;建立了双层乳胶气球的几何模型和动力学模型,结合实地施放试验,对其升空和平漂过程轨迹进行模拟,由此探究了内、外球充气量对平漂高度的影响。研究结果表明:内球充气量是决定平漂高度的主要因素,并受昼夜温度变化影响,当内、外球规格分别为750g、500g,负载约1kg时,内球拉力每增大或减小0.04kg,最终平漂高度将对应升高或降低约5km,而外球充气量对其平漂高度无影响。      

Effect of vapor condensation on ascending performance of stratospheric airship

This paper reports a numerical investigation on the effects of water vapor condensing inside the air bag of a stratospheric airship on its ascending performance. The kinetic and thermal model considering vapor condensation was established, based on which a computer program was written in Fortran. The simulation results show that the vapor condensation remarkably affects the kinetic and thermal characteristics of the stratospheric airship in the ascent process. During the ascent process below 11 km, a large amount of latent heat is released when the water vapor in the air inside the air bag of the stratospheric airship condenses, which results in the increase of the temperature and the reduction of the weight of the air in the air bag, causing the airship to speed up, the accelerated expansion of the helium, and the decrease of the helium temperature in the helium bag. When the flight altitude is higher than 11 km, the effect of vapor condensation on the kinetic and thermal characteristics of the stratospheric airship is negligible because vapor is virtually nonexistent in the air.     

Inner radiation belt source of helium and heavy hydrogen isotopes

Nuclear interactions between inner zone protons and atoms in the upper atmosphere provide the main source of energetic H and He isotopes nuclei in the radiation belt. This paper reports on the specified calculations of these isotope intensities using various inner zone proton intensity models (AP-8 and SAMPEX/PET PSB97), the atmosphere drift-averaged composition and density model MSIS-90, and cross-sections of the interaction processes from the GNASH nuclear model code. To calculate drift-averaged densities and energy losses of secondaries, the particles were tracked in the geomagnetic field (modelled through IGRF-95) by integrating numerically the equation of the motion. The calculations take into account the kinematics of nuclear interactions along the whole trajectory of trapped proton. The comparison with new data obtained from the experiments on board RESURS-04 and MITA satellites and with data from SAMPEX and CRRES satellites taken during different phases of solar activity shows that the upper atmosphere is a sufficient source for inner zone helium and heavy hydrogen isotopes. The calculation results are energy spectra and angular distributions of light nuclear isotopes in the inner radiation belt that may be used to develop helium inner radiation belt model and to evaluate their contribution to SEU (single event upset) rates.     

光纤陀螺系统热建模及仿真

在热状态方程的数学离散的基础上,从系统的角度出发,建立某一高精度光纤陀螺的热模型,介绍光纤陀螺电子系统热模型的建立过程,包括结构体几何模型的建立、内部热源模型的建立以及热敏光纤环体模型的建立.模型建立的方法不仅适用于研究对象,对于结构和组成类似的其他类型的陀螺也是适用的.并通过稳态热仿真研究了系统内热点分布及温度场分布;瞬态仿真分析了陀螺在常温(25.6℃)、低温(-40℃)以及高温(+60℃)环境下,启动过程中陀螺内部温度的变化,实验测试对比分析验证了模型的正确性.在此基础上得出了几个有意义的结论,这将有益于高精度光纤陀螺的工程化.      

Modeling and analysis of floating performances of stratospheric semi-rigid airships

In recent years, the study of semi-rigid airship has revived with the development of airships. Semi-rigid airships have some characteristics of rigid airships and non-rigid airships. Due to the flexibility of the envelope of the non-rigid airship, the variation of the temperature of the inner gas will lead to its structure deformation and affect its flight altitude. This paper develops the structural mechanics model, thermodynamic model and dynamic model of the semi-rigid airship, based on which nonlinear finite element analysis is employed for geometrically nonlinear deformation of the airship upper film in consideration of thermodynamics and structural mechanics coupling. Based on the thermal-structural interaction, the thermal characteristics and flight performances of the airship during floating flight are investigated. The 3-D solar radiation and temperature distribution of the airship skin and the temperature variation of the inner gas are presented to investigate the thermal performance of the airship, flight velocity, acceleration and flight altitude are simulated to investigate the flight performance, and the variations of the volume and pressure difference of the inner gas are calculated to provide a basis for structure design. The results of the simulation can be referenced for the design of the semi-rigid airship, and can be used for the further study on the attitude control of the airship during its floating flight.     

The theoretical advantages and practical considerations of gas replenishment techniques in long-duration scientific ballooning

Long-duration scientific balloon flights using conventional ballasting methods to compensate for daily loss of lift suffer a severe payload weight penalty. Typically, the weight of the expendable ballast approaches or exceeds the weight of the balloon and payload. This paper examines the concept of correcting for degraded lift by “gas replenishment” techniques, that is, by replacing lost helium inflatant from an on-board dewar. Appropriate equations are developed and curves are presented which demonstrate the clear theoretical superiority of the replenishment method. Design problems associated with the dewars and heat exchangers required to implement the gas replenishment concept are also discussed in detail. A series of curves is presented in which net load, dewar weight and quantity of helium required are plotted for specific balloons and float altitudes as a function of daily loss rate. The lack of relevant heat exchange data in the literature is cited as an obstacle to immediate prototype development.     

Comportement thermique de ballons pressurises stratospheriques et flux infrarouge tellurique

Pumpkin shaped pressurized balloons (214m³) were launched from Pretoria during September 1978, to perform long duration flights at 95 mb level.On board instrumentation provided information on the general state of the balloon.A thermal model was carefully worked out so that the gas temperature could be related to thermal environment conditions, in which IR earth radiation is found.A balloon trajectory was established permitting the cross-checking of the information thus obtained with that provided by the METEOSAT satellite.The similar results observed enable the researcher to improve his knowledge of this balloon type's behaviour and, to a certain extent, the behaviour of the vehicle itself enables him to gather information on thermal environment conditions, especially IR earth radiation, at flight level.