考虑水膜效应的防冰表面流动换热研究

发布时间：2018-06-25 14:12

本文选题：飞机防冰 + 水膜流动　；参考：《上海交通大学》2015年硕士论文

【摘要】：飞机及发动机进口部件结冰是影响飞行安全的重大隐患之一。通常认为,结冰发生的原因是云层中含有温度低于冰点的亚稳态液态水,当飞机穿越由这些过冷水滴组成的云团时,便会在迎风部件表面发生结冰现象。研究表明,飞机结冰会破坏飞机的气动外形,并影响其操纵性和稳定性;严重的结冰可能造成机毁人亡的重大飞行事故。为了保证飞行安全,现代飞机的设计都严格执行相关部门颁布的结冰条件适航规定,采用防、除冰系统来保障结冰环境条件下的安全飞行。目前在大型商用飞机上,普遍采用热气防冰系统。热气防冰系统通常从飞机发动机的压气机中引出带有一定压力的热空气,加热需要防冰的部件,保证部件表面的温度在冰点以上,从而避免撞击到部件表面的过冷水滴在其表面发生冻结。对于不完全蒸发热气防冰系统,当过冷水滴撞击到热气防冰表面后,未完全蒸发的液态水在气动力作用下沿机翼表面向后流动形成溢流水。溢流水的流动换热特性对确定热防冰系统的加热区域和加热功率具有重要的影响。因此,研究考虑水膜效应的防冰表面流动换热现象具有十分重要的理论意义和工程实用价值。本文主要围绕飞机防冰表面的水膜流动换热现象展开,对考虑水膜效应的防冰表面流动换热机理进行研究。主要研究内容如下:首先,本文对国内外水膜流动换热研究进展进行了简要的回顾,介绍了研究所涉及的一些基本概念和基本研究方法。在此基础上,以ANSYS FLUENT软件作为平台,实现了空气流场计算和水滴撞击特性计算,为进一步开展防冰表面的水膜流动换热研究创造了条件。其次,本文基于机翼表面水膜及空气相互作用机理,建立了水膜与空气的流动换热模型。防冰表面水膜流动换热模型考虑了气动剪切力对水膜流动的驱动效应、水膜表面的对流换热和汽化潜热,得到了溢流水膜及空气边界层流动换热的控制方程。通过与相关实验数据的对比,对所提出的计算模型的准确性进行了验证,并为进一步研究不同防冰状态下的水膜流动换热过程奠定了基础。再次,在防冰表面水膜流动换热模型的基础上,提出了连续水膜破裂后溪流流动的物理模型以及水膜破裂模型,并将计算结果与实验翼型表面溪流流态分布的测量结果进行对比,验证了水膜破裂模型的有效性。最后,基于本文提出的二维水膜流动换热模型以及水膜破裂模型,研究了不同防冰条件对水膜流动换热、水膜破裂和溪流形态的影响。本文所提出的分析方法及结果在一定程度上对防冰系统的设计可以提供参考和借鉴。由于水膜流动现象涉及多学科的交叉,物理机理非常复杂,因此本文所建立的二维水膜流动换热模型及水膜破裂模型必定还有需要完善及扩展之处。
[Abstract]:The icing of aircraft and engine inlet parts is one of the major hidden dangers affecting flight safety. It is generally believed that ice formation occurs because the clouds contain metastable liquid water with temperatures below the freezing point. When an aircraft passes through a cloud consisting of these subcooled water droplets, it will freeze on the surface of the upwind components. The research shows that the aircraft icing will destroy the aerodynamic shape of the aircraft and affect its maneuverability and stability. In order to ensure flight safety, modern aircraft design strictly implements the airworthiness regulations of icing conditions promulgated by relevant departments, and adopts anti-icing and deicing systems to ensure safe flight under the conditions of icing environment. At present, hot air ice-proof system is widely used on large commercial aircraft. The hot air anti-ice system usually draws hot air with a certain pressure from the compressor of the aircraft engine to heat the parts that need to be ice-proof, so as to ensure that the surface temperature of the parts is above freezing point. In order to avoid the impact on the surface of the subcooled water droplets frozen on its surface. For the incomplete evaporative hot gas anti-ice system, when the subcooled water droplets hit the hot air anti-ice surface, the incomplete evaporated liquid water flows backward along the wing surface under the aerodynamic force to form overflow water. The flow heat transfer characteristics of overflow water play an important role in determining the heating region and heating power of thermal ice proof system. Therefore, it is of great theoretical significance and practical value to study the flow heat transfer on ice-resistant surface considering the effect of water film. In this paper, the heat transfer mechanism of the anti-ice surface flow heat transfer considering the water film effect is studied. The main research contents are as follows: firstly, the research progress of water film flow heat transfer at home and abroad is briefly reviewed, and some basic concepts and research methods involved in the study are introduced. On this basis, using ANSYS fluent software as the platform, the calculation of air flow field and water droplet impact characteristics is realized, which creates the conditions for further research on the flow heat transfer of water film on the ice-proof surface. Secondly, based on the mechanism of water film and air interaction on the wing surface, a flow heat transfer model of water film and air is established. The driving effect of aerodynamic shear force on water film flow is considered in the model of water film flow heat transfer on ice-proof surface. The governing equations of heat transfer of overflow water film and air boundary layer are obtained by convection heat transfer and latent heat of vaporization on water film surface. By comparing with the experimental data, the accuracy of the proposed model is verified, and the foundation is laid for the further study of the flow heat transfer process of water film under different ice-resistant conditions. Thirdly, on the basis of the heat transfer model of water film flow on ice-proof surface, the physical model of stream flow after continuous water film rupture and the water film rupture model are proposed. The validity of the water film rupture model is verified by comparing the calculated results with the measured results of stream flow distribution on the surface of the experimental airfoil. Finally, based on the two-dimensional water film flow heat transfer model and the water film rupture model, the effects of different anti-ice conditions on the water film flow heat transfer, water film rupture and stream morphology are studied. The analytical methods and results presented in this paper can be used for reference in the design of anti-ice system to some extent. Because the phenomenon of water film flow involves the intersection of many disciplines and the physical mechanism is very complex, the two-dimensional water film flow heat transfer model and the water film rupture model established in this paper must be perfected and expanded.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V244.15;V233.94

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