【作者】 曹广州；

【导师】 吉洪湖；

【作者基本信息】 南京航空航天大学 ， 航空宇航推进理论与工程， 2011， 博士

【摘要】 当飞机进入含有过冷水滴的云层时,机翼和发动机进口等迎风表面会产生结冰现象,导致机翼升力减小阻力增大、发动机推力降低甚至损坏等,给飞行安全带来很大的危害,因此关于飞机/发动机迎风表面的积冰研究受到了很大的关注。目前,国外对二维积冰的研究已经比较成熟,但对三维积冰(如机翼两端以及发动机进口等)的研究还在进行之中;国内关于二维积冰的数值研究已有较多的文献报道,但对三维积冰的数值模拟研究尚处于探索阶段。本文将研究三维积冰的数学模型,发展相应的计算方法,开发三维积冰的数值模拟程序。本文首先发展了一个三维积冰模型,并据此开发了相应的积冰模拟程序。该积冰模型考虑了霜冰积冰、明冰积冰和不结冰三种情况;对明冰表面的未凝结薄水膜建立了控制方程,通过数值求解模拟其流动,克服了传统Messinger模型对水膜流动处理过于粗糙的缺点;模型中还考虑了两个相交表面角区的耦合积冰。据此所开发的积冰模拟程序可以自动判断不同来流条件下的积冰形态,并给出不同时刻的冰层厚度和水膜流动信息。其次,本文发展了一套将自主开发程序与商业软件相结合的三维积冰计算方法,提高了三维积冰数值模拟的效率。即:利用自主开发程序进行局部水收集系数的计算以及冰层生长和冰层表面水膜流动的数值模拟,借助于ICEM、CFX和UG等软件进行网格划分、稀疏两相流场计算和三维冰形构建等工作,实现了整个积冰数值模拟过程—“网格自动划分-两相流场自动更新-冰层生长和水膜流动模拟-冰层表面坐标确定和冰形构建”—的循环。再次,本文对冰层-空气对流换热、冰层-基底导热、水膜回流区以及水膜前锋区的处理等具体问题进行了细致的研究,并据此进一步完善了所开发的积冰模拟程序。在上述工作的基础上,本文通过对文献提供的一些典型对比算例的计算,初步验证了本文所建立的三维积冰模型是合理的,所发展的计算方法是可行的,据此所开发的积冰模拟程序是基本可靠的。最后,本文数值模拟了机翼-机身、机翼自由端、发动机进口支板和整流罩等部件的简化模型上的积冰过程,初步揭示了这些典型迎风表面上三维积冰的特点,显示了本文所开发程序的三维积冰模拟能力,为飞机/发动机迎风表面的积冰预测提供了一种方法和手段。更多还原

【Abstract】 When the aircraft flys into the clouds with supercooled water droplets, ice accretion occurs on the up-wind surfaces, such as airfoil and engine-inlet. The ice on the airfoil leads to lift decrease and drag increase. The ice on the engine-inlet leads to thrust lost and even engine damage. All these reduce the safty of the flight. So, much attention has been paid on the study of the ice accretion on up-wind surfaces. The simulation of 2D ice accretion has been well done while the 3D simulation is just under research in the abroad. Many papers about 2D icing simulation have been published while the 3D icing simulation is just at the beginning in our country. The current research aims at developing an icing model and corresponding calculational methodology for 3D ice accretion, and also developing a 3D ice simulating program.Firstly, a 3D icing model and the simulating program is developed. The model concerns three cases: rime ice, glaze ice and no ice. In this model, the control equations for the shallow water film flow are built. So the water flow is numerically simulated based on the equations. This is a big progress compared to the Messinger icing model in which the water flow is simply treated. The ice accretion on the corner of two intersecting surfaces is also concerned in the current model. The 3D ice simulating program is developed based on the icing model. The program can estimate which kind of ice will accrete uder different climate conditions. And it can provide the ice thickness and the informations of water flow at different time.Secondly, a calculational methodology for the 3D ice simulation is developed. In this methodology, the water collection efficiency, the ice accretion and water flow on the ice layer are simulated with the program developed in this paper. The grid genetation, two-phase flow computation and ice surface construction are done with ICEM, CFX and UG respectively. The ice simulation process, grid generation-twophase flow computation-ice accretion and water flow simulation-ice surface construction, is completed with the program and softwares. So the 3D icing simulation efficiency is enhanced.Thirdly, some improvements are added into the ice simulating program based on some detailed research about the heat convection between air flow and ice layer, the conduction between substrate and ice layer, the water flow in the reback area, the“front”of the water film, et al.Then, many icing examples are simulated and the results are compared to that provided in the published papers. Good agreement proves the icing model is logical, the calculational methodology is feasible, and the program developed in this paper is credible.Finally, the ice accretion on three simplified structures is numerically simulated. These three structures simulate the airfoil-the body of aircraft, the airfoil tip, the fairing and its strut in the engine-inlet respectively. The primary results show the characteristics of icing on these up-wind surfaces. The simulation work also shows the 3D ice simulating ability of the program developed in this paper. The research in this paper provides an approach for predicting the ice on the up-wind surfaces of the aircraft/aero-engine.更多还原