A novel inflatable rings supported design and buoyancy-weight balance deformation analysis of stratosphere airships

Owing to the unique advantages in flight altitude, dwelling time and wide coverage area,stratospheric airships provide permanent monitoring and surveillance for both civil and military applications. Here we propose a semi-rigid stratosphere airship design with circumferential highpressure inflatable rings and a longitudinal carbon fiber skeleton supported inside. We perform numerical simulations to analyze the deformation characteristics during the whole ascending and descending process. An equi...     

壁压法用于高速风洞大迎角实验力和力矩修正

 用改进的壁压法,对 Ma≤ 0 .9时飞机的大堵塞比模型、大迎角风洞实验数据进行了洞壁干扰修正计算。修正中考虑了洞壁干扰修正量分布不均匀的影响,初步解决了大迎角实验洞壁干扰修正中最困难的力矩修正问题。该方法可用于各种透气壁或实壁风洞     

实现结构轻量化的新型平流层飞艇研究进展

平流层飞艇具有极高的实用价值,是国内外临近空间开发的研究热点。和中低空常规飞艇相比,由于单位体积所提供的浮力大大降低,使得平流层飞艇设计时存在艇体体积、阻力和重量之间的循环关系,飞艇结构轻量化成为平流层飞艇研发的首要课题,受到了各国研究机构的高度重视。本文对目前实现平流层飞艇结构轻量化的主要方法和技术进行了整理,给出了利用这些方法实现结构轻量化的平流层飞艇研究进展,比较了这些方法的优势和不足,并对新型的平流层展开飞艇技术进行了分析。分析结果认为改进蒙皮材料性能、改变飞艇的结构形式和利用新型的空中展开飞艇将是平流层飞艇实现结构轻量化的主要手段,新型空中展开飞艇能够有效地实现结构轻量化,具备较好的发展潜力。     

平流层飞艇大迎角气动特性分析

为了获得大迎角下的平流层飞艇的气动特性,基于N-S方程及k-ωSST湍流模型,对某平流层飞艇的大迎角气动特性进行数值模拟分析.结果表明：平流层飞艇的大迎角失速特性及力矩特性与飞机具有较大的区别,飞艇的失速迎角较大（45°左右）;俯仰力矩特性在失速前呈现完全不同的两种趋势,小迎角范围内其静不稳定,迎角增加到一定程度后变为静稳定且维持该状态直至失速.研究结果对平流层飞艇的大迎角操稳设计、飞控设计具有重要的参考意义.     

Light weight optimization of stratospheric airship envelope based on reliability analysis

A stratospheric airship is an essential flight vehicle in the aviation field. In this paper, optimal design approach of stratospheric airships is developed to optimize envelope shape considering three failure modes and multidisciplinary analysis models, and could also reduce the mass of a stratospheric airship to be deployed at a specific location. Based on a theoretical analysis, three failure modes of airships including bending wrinkling failure, hoop tearing failure and bending kink failure, are given to describe and illustrate the failure mechanism of stratospheric airships. The results show that the location, length and size of the local uniform load and the large fineness ratio are easier to lead to bending wrinkling failure and bending kink failure. The small fineness ratio and the increasing differential pressure are more prone to cause hoop tearing failure for an airship hull. The failure probability is sensitive to the wind field. From an optimization design, the reliability analysis is essential to be carried out based on the safety of the airship. The solution in this study can provide economical design recommendations.     

齐莫曼翼与反齐莫曼翼空间流场测量对比分析

在低速风洞内,分别对齐莫曼翼和反齐莫曼翼的气动特性进行了测量,并应用PIV测试技术测量了两种微型飞行器机翼的空间流场,给出了空间流场的速度矢量图、涡量图和流线图。通过对比分析给出了两种机翼气动特性产生差别的主要流动机理。     

基于充气结构的非常规飞艇设计

研究充气结构在飞艇设计、制造和操控方面的用途,提出一种由受压变硬的空心管组成的充气结构,其安装在飞艇囊体上,使得飞艇结构变得更坚固。这种设计创新可以降低结构质量,也可提高非常规飞艇的动力和机械性能。同时,由于这些充气结构的简易性,制造和操作过程中面临的难题将会大大减少。     

平流层飞艇尾部形状对气动阻力的影响

为了研究平流层飞艇尾部动量边界层厚度与尾涡结构,应用LES(大涡模拟)方法计算了零攻角工况下飞艇绕流场,并对LOTTE和M-LOTTE两种飞艇进行了对比分析.采用Q分布和涡量描述回转体尾涡结构,根据Q分布可以确定M-LOTTE飞艇较LOTTE飞艇尾部分离区显著减小;并分析了回转体的轴对称曲面动量边界层厚度对飞艇气动阻力的影响,随着飞艇尾部厚度逐渐减小,动量边界层厚度逐渐增大,M-LOTTE飞艇尾部动量边界层厚度明显小于LOTTE飞艇.飞艇尾部动量边界层厚度分布说明了M-LOTTE飞艇的总阻力系数较LOTTE飞艇降低17.2%的原因,同时也表明飞艇尾部形状对飞艇气动阻力影响较大.      

升力体式浮升混合飞艇设计及参数分析

升力体式浮升混合飞艇将艇体设计为具有较大升阻比的气动外形,升力由静浮力和气动力共同提供,适用于复杂地形下的大载重运输。控制速度和迎角的变化可有效控制动升力的大小,矢量推进系统的增加共同提高了飞艇的可控性,气垫着陆系统(ACLS)有效降低了地面保障系统的复杂度。多项系统的有效集成对总体设计提出较高的要求,通过重量平衡和推阻平衡的关系,对浮升混合飞艇进行了总体设计,分析了浮重比、巡航速度等参数对于总体性能的影响规律,同时研究了浮升飞艇气动性能、总体飞行性能和经济性能,为后续详细设计和有效控制方法的研究提供基础。     

临近空间飞艇排翼式艇翼气动干扰实验研究

临近空间排翼式升浮一体飞艇是运行在临近空间环境,由水平、垂直方向具有一定几何间隔的两个艇翼连接两个囊体构成的新型低速飞行器。本文通过研制附加支架,使用一种低雷诺数风洞测量了两个对称翼型在水平、垂直方向相对位置、雷诺数、迎角等参数变化的情况下,前翼型模型对后翼型模型的升力和阻力系数于扰值的定量结果;对其变化规律进行了总结,并通过自由飞模型对由实验数据推导出的前、后机翼间的气动干扰进行验证,得出一些对排翼式布局飞行器总体设计有指导意义的经验数据与结论。     

Experimental investigations on hull-fin interferences of the LOTTE airship

In the present paper experimental aerodynamic investigations on an airship configuration at angle of attack with special emphasis on the hull-fin region are reported. In particular, visualizations of flow phenomena on both hull and fins are studied. Quantitative measurements of the integral force and moment characteristics as well as local pressure coefficients serve to establish a data pool for code validation.     

Unsteady flow phenomena associated with leading-edge vortices

This paper presents selected results from extensive experimental investigations on turbulent flow fields and unsteady surface pressures caused by leading-edge vortices, in particular, for vortex breakdown flow. Such turbulent flows may cause severe dynamic aeroelastic problems like wing and/or fin buffeting on fighter-type aircraft. The wind tunnel models used include a generic delta wing as well as a detailed aircraft configuration of canard-delta wing type. The turbulent flow structures are analyzed by root-mean-square and spectral distributions of velocity and pressure fluctuations. Downstream of bursting local maxima of velocity fluctuations occur in a limited radial range around the vortex center. The corresponding spectra exhibit significant peaks indicating that turbulent kinetic energy is channeled into a narrow band. These quasi-periodic velocity oscillations arise from a helical mode instability of the breakdown flow. Due to vortex bursting there is a characteristic increase in surface pressure fluctuations with increasing angle of attack, especially when the burst location moves closer to the apex. The pressure fluctuations also show dominant frequencies corresponding to those of the velocity fluctuations. Using the measured flow field data, scaling parameters are derived for design purposes. It is shown that a frequency parameter based on the local semi-span and the sinus of angle of attack can be used to estimate the frequencies of dynamic loads evoked by vortex bursting.     

Supersonic flow over a pitching delta wing using surface pressure measurements and numerical simulations

Experimental and numerical methods were applied to investigating high subsonic and supersonic flows over a 60° swept delta wing in fixed state and pitching oscillation.Static pressure coefficient distributions over the wing leeward surface and the hysteresis loops of pressure coefficient versus angle of attack at the sensor locations were obtained by wind tunnel tests.Similar results were obtained by numerical simulations which agreed well with the experiments.Flow structure around the wing was also demonstrated by the numerical simulation.Effects of Mach number and angle of attack on pressure distribution curves in static tests were investigated.Effects of various oscillation parameters including Mach number, mean angle of attack, pitching amplitude and frequency on hysteresis loops were investigated in dynamic tests and the associated physical mechanisms were discussed.Vortex breakdown phenomenon over the wing was identified at high angles of attack using the pressure coefficient curves and hysteresis loops, and its effects on the flow features were discussed.     

大攻角地效翼非定常流动实验研究

大攻角地效翼非定常流动研究对大攻角地效翼非定常空气动力特性和流动控制具有重要的意义。对攻角为18°的NACA0012地效翼在模型风洞中进行实验,利用三维热线风速仪对地效翼后缘附近尾迹区内测点的速度脉动进行采样,分析不同飞行高度下大攻角地效翼的非定常流动特性。结果表明：地面效应下,大攻角地效翼后缘涡系形成位置后移;随着地效翼高度的降低,非定常流动的脉动频域宽度减小,速度脉动特征频率减小。     

高速下模型头部扰动与非对称涡流动响应研究

采用尖拱细长旋成体模型,在M=0．4～1．2范围内,通过表面压力测量和PIV流态观测手段,对高速情况下模型头尖部微扰动与大迎角非对称涡流动的响应关系进行了研究。研究结果表明：在此高速范围内,尖拱细长旋成体的大迎角流动仍然呈现出非对称多涡结构,头部微扰动对非对称涡有影响,但对模型的非对称气动力影响不明显。     

飞艇空气动力学及其相关问题

对低空和高空飞艇在发射、回收、驻留、巡航或系留状态下所涉及的空气动力学问题及其重要性进行分析,介绍飞艇空气动力学研究的进展和主要结论,指出需要进一步解决的问题。低空飞艇的空气动力学问题主要包括厚艇身带来的流动分离与减阻、非薄平组件的非线性干扰、柔弹性表面或系留带来的流固耦合、因低速飞行带来的环境敏感性等。大量学者进行了相应的研究。高空即平流层飞艇还涉及多种新的空气动力学问题,包括热、浮力与气动的强耦合、昼夜外形变化、发射与回收过程中的突风带影响、风切变干扰等。关于这些问题的研究处于起步阶段。另外,还针对地面及大气边界层的影响、多边形外形以及副气囊喷流与主流干扰等很少有人研究的问题对飞艇周边流场进行了初步数值模拟。     

飞艇续航时间论证方法研究

由于飞艇续航时间受飞行速度、重力浮力配平方式、载油量变化、风场条件等多种因素的影响,飞机续航时间计算方法并不适用于飞艇,因此提出了一种新的基于试验设计和统计分析方法的飞艇续航时间论证方法。分析了工作高度的风场速度分布规律,分别给出完全靠发动机推力矢量平衡和完全靠动升力平衡两种不同情况下飞艇续航时间计算方法,以某大型对流层飞艇为研究对象,计算了初始方案在不同平均巡航速度、配平重量和配平方式下的平均燃油消耗率和最大续航时间,对经过减阻、减重、减少耗油率等技术改进后优化方案能达到的续航时间和概率进行了分析和论证。研究表明,某飞艇初始方案在使用区域风场条件下基本能满足留空时间72h的指标要求,经技术改进后,指标仍有较大的提升的空间。方法考虑了飞艇续航时间的多种影响因素、取值变化和交互影响,比较适宜在飞艇这类涉及重浮力配平和任务耗油率变化的浮空器上使用。     

冲压发动机用轴对称进气道设计和试验

完成了一种Ma=2.5～4.0冲压发动机用超声速轴对称混合式进气道模型的设计,通过数值模拟和风洞试验,获得了马赫数Ma=2.5,3.0,3.5,4.0,攻角α=0°,3°,6°,8°条件下的超声速轴对称混合式进气道性能。试验结果表明,随着马赫数的增加,总压恢复系数大幅度下降,亚临界稳定范围变窄,流量系数逐渐增加;随着攻角的增大,总压恢复系数和流量系数总体都呈降低趋势,在Ma≥3.0,α=6°时,进气道性能的下降小于5%,亚临界稳定范围变窄。     

"空中列车"系统的研究与设计

本文主要介绍了“空中列车”系统的研究与设计,即采用一艘动力艇牵引几艘拖艇的多艇串联的方法,对飞艇的总体和局部进行了研究与设计。