基于微观物理现象的飞机结冰特性研究

发布时间：2018-05-17 11:51

本文选题：飞机结冰 + 数值模拟　；参考：《南京航空航天大学》2016年硕士论文

【摘要】：飞机在飞行过程中遇到特定气象条件时,会发生结冰并改变原来的外形,从而对其气动特性、操纵性以及稳定性等造成破坏,给飞行安全带来隐患。实际的结冰是一个多学科综合的复杂物理过程,对该过程进行数值模拟时需要建立相对应良好的模型才能获得较为准确的结果。现阶段国内外大部分学者采用的都是基于Messinger思想的数值模型,这类模型普遍有着简单、准确、易于计算等优势,但是由于模型的连续性,使其在结冰的微观现象捕捉方面有所不足。因此本文在考虑单个水滴离散运动的情况下,采用了一种基于Szilder思想的新模型来进行结冰预测数值模拟。文中的主要工作有:(1)采用高效的CFD软件Fluent对机翼绕流流场进行模拟,并将计算所得的机翼表面压力系数与相关试验数据进行了对比,说明了该方法的可行性。(2)为了考察数值模拟冰形在研究结冰对机翼气动特性影响中的有效性,对一组试验冰形和基于Messinger模型的数值模拟冰形在ICEM中进行了结构化网格划分,并在Fluent中分别进行了两种冰形在不同攻角情况下的升阻力系数计算,通过对结果的分析说明了数值模拟冰形在计算结冰后的机翼气动特性时存在一定的误差。(3)利用欧拉法建立了水滴运动特性的控制方程,进行了几组不同直径下的水滴撞击特性的计算,得到了结冰机翼表面的水滴收集系数,为结冰预测提供了初始条件。(4)基于一种新的思想建立了随机结冰模型,其中包括水滴的随机发射模型、随机运动模型以及结冰概率模型。编写了模拟结冰的程序,并对不同条件下的结冰进行了数值预测,最后将模拟冰形与试验值以及基于Messinger模型的CIRAMIL的计算结果进行了对比,并对随机结冰模型的优劣提出了评价。
[Abstract]:In the course of flight, the aircraft will freeze and change its original shape, which will destroy its aerodynamic characteristics, maneuverability and stability, and bring hidden trouble to flight safety. The actual icing is a complex physical process which is synthesized by many subjects. In order to obtain more accurate results, a good corresponding model is needed for numerical simulation of the process. At present, most scholars at home and abroad adopt numerical models based on Messinger thought. These models generally have the advantages of simple, accurate and easy to calculate, but because of the continuity of the model, It is insufficient in catching the microscopic phenomenon of ice formation. In this paper, a new model based on Szilder is used to simulate the ice formation in the case of discrete motion of single water droplet. The main work in this paper is: (1) the flow field around the wing is simulated by using the efficient CFD software Fluent, and the calculated surface pressure coefficient of the wing is compared with the experimental data. The feasibility of this method is illustrated. In order to investigate the effectiveness of numerical simulation ice shape in studying the effect of icing on the aerodynamic characteristics of wing, a group of experimental ice shapes and numerical simulation ice shapes based on Messinger model are divided into structured meshes in ICEM. The lifting resistance coefficient of two ice shapes at different angles of attack is calculated in Fluent. The analysis of the results shows that there is a certain error in the calculation of the aerodynamic characteristics of the frozen wing in the numerical simulation of the ice shape. The Euler method is used to establish the governing equation of the motion characteristics of the water droplets. In this paper, several groups of water droplets with different diameters are calculated, and the water droplet collection coefficients on the surface of the frozen wing are obtained. The initial conditions for ice prediction are provided. (4) based on a new idea, a stochastic icing model is established. These models include the random emission model of water droplets, the random motion model and the icing probability model. The program of simulating icing is compiled, and the ice formation under different conditions is predicted numerically. At last, the simulated ice shape is compared with the experimental data and the calculated results of CIRAMIL based on Messinger model, and the merits and demerits of stochastic icing model are evaluated.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V321.229

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