软式平流层飞艇的气动性能与多目标优化研究

发布时间：2018-03-19 21:50

本文选题：软式平流层飞艇　切入点：气动特性　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：平流层飞艇是靠体内浮升气体提供净升力,靠推进系统抵抗气动阻力及控制系统调整姿态,可实现在平流层底部(约20km左右)长时间定点驻空的浮空器。悬空时间长、载重量大、隐身性能好、成本低等特点,使平流层飞艇具有重要的军事与民用价值,已经成为国内外的研究热点。平流层飞艇工作高度处的空气密度仅约为地面的1/14,意味着需要更轻质量及更大体积来产生足够的净升力。软式飞艇以其质量轻、可实现大体积的特点成为平流层飞艇的首选结构形式。风荷载是平流层飞艇工作过程中的主要外荷载,风荷载作用下的气动特性是飞艇结构设计的主要控制因素。该方面以往的研究多集中在双椭球艇的测力试验,缺少测压试验,尤其缺乏软式飞艇气动弹性效应的风洞试验研究。与此同时,续航能力、载重量及结构受力性能是评价平流层飞艇性能的关键指标。续航能力的增加主要是靠减少气动阻力节约动力能源来实现的。与其它飞行器相比,飞艇自重对载重量的影响更直接。因此,需要开展减阻、减重与提高结构受力性能的多目标优化。基于上述背景,本文以某艇形软式平流层飞艇为研究对象,综合运用风洞试验与数值模拟,对飞艇的气动性能进行了系统性研究。在此基础上,基于本文提出的优化分析算法,对飞艇进行了多目标优化分析。主要工作包括如下几个方面:(1)为了从风压分布角度更好地理解飞艇气动特性的规律,设计并完成了缩尺比为1/30飞艇刚性模型的测压风洞试验。分析了偏航角、俯仰角及复合角(偏航与俯仰共同作用)下结构的气动特性;根据研究艇体的外形特点,将其定义为头部、中间、尾部三个部分。基于风压分布特点,讨论了各部分对艇体气动特性的影响。(2)为了对飞艇的气弹响应进行准确的评价,设计并完成了飞艇气弹响应风洞测振试验。对气弹模型设计中不满足相似性要求的相似偏差进行了评价,且给出了相应的修正;基于数字图像相关技术获得了飞艇的气弹响应值,探讨了风速、压差及姿态对气弹响应的影响;对飞艇的气弹响应进行了评价,结果表明:本文研究飞艇在驻空高度处的气弹响应较小,可以忽略不计。(3)飞艇的气动阻力对其驻空时长及载重量等性能有重要的影响,为此,采用CFD数值模拟技术,对飞艇的气动阻力特性进行了系统的分析。探讨了环境参数、长细比及尾翼对结构气动阻力的影响。基于CFD数值模拟结果,拟合出气动阻力系数估算式,且给出艇体的分区平均风压系数。(4)为了提高多目标优化的效率,在评价与改进现有参数敏感性分析方法与多目标优化算法的基础上,提出了基于敏感性的多目标优化算法,开发了用户界面。在该算法中,优化个体作为参数敏感性分析的样本,参数敏感性分析的结果可以直接指导优化进程,且在一次进化过程中可同时获得优化结果与敏感性结果。算例分析表明,该算法可以获得精确性更高、均匀性更好的多目标优化解集。(5)基于飞艇的非线性受力分析,建立了飞艇的多目标优化模型,采用前文所提的优化算法对飞艇进行了减阻、减重及提高受力性能的多目标优化。在此基础上,采用基于信噪比的决策方法,从优化所得的Pareto解集中选择满足设计要求的最稳健方案。
[Abstract]:Stratospheric airship is on body floating gas provided by net lift, propulsion system aerodynamic resistance and resistance adjustment of attitude control system, can be realized in the lower stratosphere (around 20km) aerostat in long time point empty. Suspended long time, large carrying capacity, good stealth performance, low cost and other features, the stratospheric airship with the military and civilian value, has become a research hotspot at home and abroad. At the height of the stratospheric airship work air density is only about 1/14 of the ground, implies the need for more light quality and greater volume to generate enough lift net. Soft airship with its light weight, can realize the characteristics of large volume are preferred structure of the stratospheric airship. The wind load is mainly outside the stratospheric airship during working load, wind load is the main aerodynamic characteristics of the airship control structure design factors. The research aspects of the past Focus on force test of double ellipsoid boat, the lack of pressure test, especially the lack of wind tunnel test on the blimp aeroelastic effect. At the same time, endurance, load and structure stress performance is the key indicator to evaluate the performance of stratospheric airship. The main increase endurance if by reducing aerodynamic drag power to achieve energy saving. Compared with other aircraft, airship weight more direct impact on the load. Therefore, to carry out drag reduction, multi-objective optimization weight loss and improvement of the mechanical properties of structure. Based on the above background, this paper takes a boat shaped flexible stratospheric airship as the research object, the integrated use of wind tunnel test and numerical simulation of airship the dynamic performance of the systemic research. Based on the analysis of algorithm optimization is proposed in this paper based on the multi-objective optimization of the airship. The main work includes the following aspects: (1) In order to better understand the wind pressure distribution from the angle of airship aerodynamics, designed and completed the scale of the wind tunnel test for the 1/30 model. The analysis of rigid airship yaw angle, pitch angle and compound angle (interaction of yaw and pitch) under the aerodynamic characteristics; according to the shape characteristics of the hull, the the definition of head, middle and tail of three parts. The characteristics of wind pressure distribution on each part of the dynamic characteristics of submarine gas is discussed. (2) in order to accurately evaluate the aeroelastic response of the airship, the airship designed and completed the aeroelastic response of vibration test of wind tunnel. The aeroelastic model design does not meet the similar the deviation of the similarity requirements were evaluated, and the corresponding correction; digital image correlation technique to obtain aeroelastic response value of Airship Based on wind speed, pressure difference and attitude influence on the aeroelastic response of the aeroelastic airship; The response was evaluated, and the results show that the research of airship aeroelastic response at the height in the air is small, can be neglected. (3) the airship aerodynamic resistance has an important influence on the length and weight in space-time performance therefore, using CFD numerical simulation technology, the dynamic characteristics of resistance to the airship gas are systematically analyzed. Discusses the environmental parameters, slenderness ratio and tail drag effect on the structure of gas. The results of CFD numerical simulation based on the fitting of the pneumatic resistance coefficient formula, and given the hull partition coefficient of mean wind pressure. (4) in order to improve the efficiency of multiobjective optimization, evaluation and improvement in the existing parameters the sensitivity analysis method based on multi objective optimization algorithm, proposed multi-objective optimization algorithm based on sensitivity, user interface is developed. In this algorithm, the optimization of the individual as a parameter sensitivity analysis of samples, the sensitivity analysis of parameters The results can directly guide the optimization process, and can simultaneously obtain the optimal results and sensitivity results in an evolutionary process. Examples show that this algorithm can obtain more accurate solutions of multi-objective optimization uniformity is better set. (5) the airship nonlinear stress analysis based on the established goals the optimization model of airship, the optimization algorithm is proposed to improve the drag reduction of the airship, and multi-objective optimization of mechanical performance of weight. On this basis, the decision method based on signal-to-noise ratio, the most robust solution scheme to meet the design requirements on the optimization of the Pareto.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：V211.54

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