【作者】 郑彬；

【导师】 杜永平； 常秋英；

【作者基本信息】 北京交通大学 ， 安全科学与工程， 2015， 硕士

【摘要】 随着飞行器的迅速发展,气动加热成为高超声速飞行器设计和研制的重点研究问题。当飞行器以超声速甚至高超声速飞行时,由于空气的粘性阻滞作用,壁面边界层内具有很大的速度梯度,导致各气流层产生了强烈的摩擦,强烈的气动摩擦使壁面附近的气温急剧升高,而高温气体又不断向飞行器低温壁面传热,进而引起很强的气动加热,有很大的可能致使飞行器的结构外形发生烧蚀、结构强度以及刚度等发生改变,对高超声速飞行器的正常飞行以及安全问题带来极为严重的影响。而近年来微结构减阻技术的研究取得巨大的进步,本文对国内外微结构减阻技术的研究现状及进展进行总结,通过对湍流产生机理及近壁面湍流结构模型的分析,从“第二涡群”和“突出高度”理论两个方面分别阐述了微结构减阻的机理,发现大量的试验和实际应用证明了微结构减阻的可行性。本文尝试将微结构技术应用在高超声速飞行器的表面,通过仿真,来研究表面微结构对高超声速气动热的影响。首先,通过二维的模拟仿真,发现直角三角形微结构,以100m/s入口处速度为例,可以将前壁面的平均速度降低到v=15.67m/s,后壁面的平均速度降低到v=24.49m/s,大大减小了壁面摩擦阻力。然后,采用CFD分析软件Fluent对某一型号的飞行器进行了整体气动热的分析,并对比不同飞行马赫数以及飞行环境参数下飞行器的气动热情况。在上述研究的基础上,在舵翼处增加表面微结构,研究了表面微结构的存在对绕流流场特性尤其是近壁面处边界层内流动的影响,进而分析表面微结构对气动加热热流的影响。结果发现增加顺流向贯通微结构的舵翼平均温度为909K,与未增加微结构的933K相比降低了24K,降温率达到2.57%。并通过对比不同尺寸及形状的表面微结构,得到降温效果最佳的微结构为顺流向三角形肋条状贯通微结构。论文所完成的有关表面微结构湍流边界层减阻的机理分析以及数值模拟仿真计算,对将来进一步深入开展该领域的研究工作具有重要的参考和指导意义。更多还原

【Abstract】 With the rapid development of the vehicle, the aerodynamic heating becomes the key research question of hypersonic vehicles’design and development. When the vehicle flies by supersonic or hypersonic, due to the viscous blocking effect of air, the air in the boundary layer has a large velocity gradient which leads to the air layer produce strong friction. The strong aerodynamic friction makes the temperature near the wall rise sharply. The high temperature air keeps transferring heat to low temperature wall of the vehicle, then causes the strong aerodynamic heating. This may lead to the vehicle’s structure shape ablation, structural strength and stiffness changing. This brings serious impact on the normal flight of hypersonic vehicle and security issues.Recently the micro-structure drag reduction technology has made great progress. In this paper, research status and progress of the micro-structure of the drag reduction technology were summarized. By analyzing the mechanism of turbulence and structure of the model of turbulence near the wall, the mechanism of drag reduction from micro-structure was discussed in two aspects,"the Second Vortex" theory and "the Protrusion Height Theory". A lot of testing and practical applications proved the feasibility of drag reduction of micro-structures. This paper attempted to apply micro-structure technology to the surface of hypersonic vehicle, and observed the effect of surface micro-structure on hypersonic vehicle heating reduction.Firstly, we found that when using triangle micro-structure, with two-dimensional simulation, the average velocity of front wall reduced to15.67m/s; the average velocity of rear wall reduced to24.49m/s. So using triangle micro-structure can greatly reduce the wall friction drag.In addition, the paper adopted the soft of Computational Fluid Dynamics, Fluent to simulate overall aerothermal of a certain type vehicle, and compared the vehicle aerothermal situation with different environmental parameters and flight Mach number.Finally, based on these studies, we added the surface micro-structure on the rudder wing and researched the effect of the existence of surface micro-structure to the flow field characteristics, especially the impact of the boundary layer near the wall. And then analyzed of surface micro-structure’s effects on aerodynamic heat flux. Throw the simulation, we found when adding along-flow-through micro-structure of the rudder the average temperature was909K, compared to non-micro-structure(933K), the temperature reduced24K, the cooling rate was2.57%. By comparing different sizes and shapes of the surface micro-structure, finally obtained the best cooling effect of the micro-structure.All analysis on mechanism of surface micro-structure turbulent boundary drag and numerical simulation calculations in the paper, there will be important significance and reference to the further research in this field.更多还原