【作者】 李小建；

【导师】 方贤德；

【作者基本信息】 南京航空航天大学 ， 人机与环境工程， 2013， 博士

【摘要】 作为高空平台，临近空间浮空器由于滞空时间长、低成本和可重复使用等优点，在军事上具有很好的使用价值，美、韩、日等国家已经对其开展了大量研究。在浮空器设计领域，一个很重要的问题是在设计和运行控制中预测内部气体温度变化特性，因为浮空器浮力取决于囊体内的气体温度与环境空气温度的差值。平流层浮空器外部蒙皮主要采用膜结构，其整体刚度小，一般为柔性，内部气体温度变化会导致浮空器蒙皮结构发生非线性变形，反之，浮空器结构变形也会影响到内部气体温度变化。因此，浮空器热力学与结构力学的相互作用是一个复杂的热-结构耦合问题。本文围绕着临近空间浮空器热-结构耦合问题开展了一系列研究，主要工作和成果如下：(1)建立了平流层飞艇热力学模型，据此设计了计算程序，并用实验数据验证了其准确性。用实验数据验证的计算程序对平流层飞艇滞空过程中的热力特性进行了分析，给出了飞艇蒙皮和内部气体温度瞬态变化规律，并研究了蒙皮辐射物性参数、周围风速以及飞艇姿态角对飞艇内部气体温度以及蒙皮温差的影响。(2)建立了飞艇表面光伏电池的三层导热模型，结合平流层飞艇的热力学模型获得了光伏电池与平流层飞艇耦合分析模型。根据所得数学模型，对平流层飞艇热特性计算程序进行了升级。利用升级后的计算程序，分析了光伏电池热力特性及其输出功率，研究了纬度和风速对光伏电池输出功率的影响以及光伏电池对飞艇热特性的影响。(3)建立了膜结构数学模型，据此设计了柔性薄膜变形计算程序，并进行了验证。将膜结构数学模型与飞艇的热力学模型相耦合，在此基础上设计出了平流层飞艇热-结构耦合数值模拟程序。利用该程序对飞艇蒙皮结构力学特性进行了研究，分析了蒙皮内外压差、蒙皮弹性模量以及泊松比等参数变化对飞艇蒙皮结构变形以及蒙皮应力的影响，为飞艇蒙皮结构设计提供了参考依据；对飞艇定点悬停过程中夜间和正午时刻进行了稳态热-结构耦合分析，揭示了蒙皮弹性模量、蒙皮辐射参数对飞艇内部气体温度、内外压差、飞艇体积以及滞空高度的影响；对飞艇滞空飞行和滞空悬停两种工作情况下的瞬态过程进行了热-结构耦合分析，预测了平流层飞艇内部气体昼夜温度变化以及蒙皮内外压差昼夜变化情况，计算出了蒙皮最大应力，作为判断平流层飞艇滞空过程中是否会出现破裂的依据。(4)建立了高空超压气球热-结构耦合数学模型，据此设计出了高空超压气球热-结构耦合数值模拟程序。利用该程序对超压气球蒙皮结构力学特性进行了研究，分析了加强筋数量、最大瓣角、蒙皮和加强筋弹性模量、蒙皮泊松比等参数变化对超压气球性能的影响，并对“南瓜形”与正球形（含加强筋、不含加强筋）三种结构超压气球的结构性能进行了对比分析，为高空超压气球蒙皮、加强筋以及结构设计提供了参考依据；对高空超压气球进行了热-结构耦合分析，预测了超压气球内部气体昼夜温度变化以及蒙皮内外压差昼夜变化情况下蒙皮的最大应力，用以判断超压气球滞空过程中是否会出现破裂现象。此外，还针对“等角度”南瓜形超压气球提出了设计思路，为超压气球的设计打下了一定的基础。更多还原

【Abstract】 As a high-altitude platform, the near space airship has a great range of performance capabilityavailable to be exploited for commercial and military sectors. The main benefits of near space airshipare extended durations, low cost, and recycling. Currently, many developed countries, such as theUnited States, South Korea and Japan, have carried out intensive investigations of the research anddevelopment of near space airship. As is well known in the field of airship design, it is very importantto predict the inner gas temperature for the design and operation of an airship because its buoyancydepends strongly on the temperature difference between the inner gas and surrounding air. For thenear space airship skin, membrane structure is adopted. The membrane with the characteristic of lowrigid is taken as a flexible structure. The temperature variations of the inner gas may cause themembrane structure to deform, while the deformation alse influence the temperature of inner gas. Theinteraction between the temperature of the inner gas and the nonlinear large deformation is acomplicated thermal-structure coupling problem.In the paper, a series of studies on the thermal-structure coupling problem of near space airship isdone. The main contents are as follow:(1) The thermodynamic model of the stratospheric airship is developed, based on which thecalculation program is implemented and verified by comparing the calculated values with theexperimental results. By numerical simulation, the thermal characteristics of the airship is explored,and the transient temperature variations of the skin and inner gas are presented. The effects ofradiative properties of the skin, wind velocity and attitude angle of the airship on the temperturevariations of buoyancy gas and the non-uniform temperture distribution of the skin have beenanalysed.(2) The three-layer heat conduction model of the photovoltaic array is developed and coupled withthe thermaldynamic model of the stratospheric airship, and then the photovoltaic array and airshipcoupling analysis model is developed. According the coupling model, the calculation programprogram of thermal characterics of the ship updates to estimate the thermal performances and outputpower of the array, the effects of the latitude, wind velocity and insulation on the power output of thePV array are analyzed and the effect of the PV array on the thermal characteristics of the airship isinvestigated.(3) The mathematical model of membrane structure is developed, the computational program ofmembrane deformation is implemented, and the validity and the accuracy of the computationalprogram are evaluated. Based on coupling the membrane strucuture model with thermodynamicmodel of the airship, the program of numerical simulation about thermal-structure coupling problemof the stratospheric airship is designed. By using the program, the structure analysis of thestratospheric airship is studied on, the effects of the differential pressure and elastic modulus andPoisson ratio of the skin on the structural deformation and the stress of the stratospheric airship areanalyzed, which offer references for structure design of the stratospheric airship. The steadythermal-structure analysis to the stratospheric airship in spot hover at night and noon is discussed. Theeffects of elastic modulus and radiative properties of the skin to the temperature of the inner gas,differential pressure, and the volume and flight altitude of the airship are analyzed. The transient thermal-structure analysis to the stratospheric airship is carried on during spot hover and floatingflight. the variation of inner gas temperature and pressure can be predicted precisely. The maximummain stress of the skin can be obtained, which is used to discern whether the stratospheric airship maybrust during floating flight.(4) The thermal-structure model of super pressure balloon is developed, the structure analysis of theballoon is done, and the effects of the number of the tendons, subtended angle at equator, elasticmodulus and Poisson ratio of the skin, elastic modulus of the tendons on the super pressure balloonare investigated. The structure behavior of Pumpkin-shaped and spherical balloons are compared andanalyzed. The study and analysis would offer references and experiences for structure design of thesuper pressure balloon. The transient thermal-structure analysis to the super pressure balloon is given.The maximum main stress of the skin and the maximum tension of the tendon can be accuratelypredicted to examine whether the balloon may brust, when the temperature and pressure of inner gasvaries from day to night. At last, the paper proposes a new way to design “Constant Angle”pumpkin-shaped balloon which could be good fundamentals for the design of the super pressureballoon.更多还原