【作者】 侯玉柱；

【导师】 董葳；

【作者基本信息】 上海交通大学 ， 航空宇航推进理论与工程， 2009， 硕士

【摘要】 飞机在含有过冷水微滴的云层中飞行时,机身部件如风挡玻璃、机翼和垂尾等,可能会出现结冰现象。这对于飞机是非常危险的,因为它会改变其原有的气动外形,使得整机升力下降,阻力增加,操控性变差。飞机发动机也存在相似的问题。对涡轴发动机来说,其进气道中导向叶片上的积冰会引起进气状况恶化,脱落的积冰也可能进入发动机内部而使其损坏。为了减小结冰问题带来的危害,现代飞机上通常都装备有防冰系统。本文以目前应用较广的热气防冰系统为研究对象,在前人工作的基础上,对现有飞机热气防冰系统热平衡分析模型加以改进,力求使得模型分析结果更为准确,能够为飞机及发动机的防冰系统性能分析提供更为可靠的计算方法。本文的工作主要包括热气防冰系统引气管路流动仿真,二维水撞击特性的数值计算、热平衡分析模型的改进、防冰部件壁面温度计算程序的编写及结果分析四部分。论文对现有防冰系统的热平衡方程进行理论分析并加以改进,在热平衡分析模型中引入表面湿润系数F构建新的数学模型,在此基础上利用某发动机导向叶片作为算例,对其进行流场分析。在流场计算分析基础上,通过编写专用程序计算叶片壁面的温度场分布。论文最后对基于新旧两种数学模型下的温度场分布作比较分析。通过以上分析建模以及计算,得出表面湿润系数F=0.2时计算出的温度场要高于表面湿润系数F=1.0时的温度场,计算结果说明原有不考虑表面湿润系数的方法低估了壁面温度,会造成防冰系统引入过量的热空气,从而降低发动机的效率。同时,论文通过比较防冰系统热气防冰过程中各项热流所占比例,发现水微滴动能转变而来的热流所占总热流值的比例很小,因而可以在精度要求不是很高的前提下忽略。更多还原

【Abstract】 Ice accretions may occur on certain exposed parts of an airplane, such as the windscreen, the aerofoil, and the tail when the airplane flies in clouds which contain super-cooled water droplets. This is very dangerous since ice accretions can seriously degrade aircraft performance and handling characteristics. Similar problem also exists on aircraft engines. For turbo-shaft engine, ice accumulated on the inlet guide vane of the engine can worsen air ingestion. In addition, shed ice may be sucked into the engine and induces serious damage. In order to reduce the hazards caused by in-flight icing, most modern airplanes have been equipped with anti-icing systems.This thesis investigates a widely used hot air anti-icing system and makes improvement of current computation model in order to get better results, trying to find a simple and effective method to evaluate its performance. The work is carried out in simulating air intake pipelines of the hot air anti-icing system, presenting a numerical method for calculating the water droplet impingement efficient, improving the thermal balance analysis model, developing a program for calculating the surface temperature. First, the current thermal balance model is improved by introducing a factor—wetness factor F. Then the guide vane is modeled, fluid field around the guide vane is also analyzed, followed by a program for calculating surface temperature is developed. At the end, the results are analyzed and compared with those based on the former model. In conclusion, it is found that the surface temperature is higher than that based on the previous way, which means the previous way is a waste of hot air. According to the new results, less hot air is needed, which will significantly improve the engine performance. The heat transfer from the kinetic energy of the droplets can be ignored because it just takes a small count of the total by comparing the percent of different heat flux.更多还原