摘要
尾迹云广泛出现在空中交通工具活动中,为了描述尾迹云的形状、数密度以及尺寸分布等特性,以同轴喷管为研究对象,采用了基于求积矩方法的欧拉-欧拉法以及k-ωSST湍流模型对伴随异质凝结过程的同轴喷管自由射流进行数值模拟,分析了尾迹云的形成机理以及凝结射流流场的流动特性,并获取了尾迹云的特性参数.结果表明,颗粒在湍流扩散作用下,颗粒的数密度在射流主体段与气相组分具有近似的扩散现象;异质凝结过程中颗粒尺度增长剧烈,消耗大量的水蒸气,使得射流中水蒸气组分降低,以及颗粒数密度分布与颗粒相体积分数的分布出现错位现象,但水蒸气绝对含量小,凝结放热最高仅将射流温度提高了0.5 K,对射流发展的影响几乎可以忽略;由于计算域内颗粒体积的增长率远远大于其缩小率,冰晶颗粒不会在计算域内发生明显消逝,而将在远离射流的大气中缓慢消亡;计算域内的尾迹云形状随射流发展先呈圆环状,再呈鸭梨状,最后呈圆锥状,其粒径分布从分散向集中发展,最后呈近似正态分布,粒径主要集中在0.8–2.0μm,该范围的颗粒约占尾迹云内颗粒的83%.
Contrails frequently appear in the activities of air vehicles.The Euler-Euler approach based on the quadrature method of moments with the k-ωSST turbulence model is used to simulate the free jet of the coaxial nozzle with heterogeneous condensation to explain the shape,number density,and size distribution of contrails.The investigation analyzes the formation mechanism of the contrail and the flow characteristics of the free jet and obtains the parameters of the contrail.The results reveal that considering the turbulence effect on the particle phase,the diffusion of the particles and the gaseous species has a similar performance in the main section of the jet.With heterogeneous condensation,which consumes a component of the vapor,the particle sizes sharply increase,causing the vapor mass fraction of the jet to considerably decrease and the particle number density and volume fraction distributions to become dislocated.The absolute content of vapor is too small;therefore,the condensation heat release only increases the jet temperature by0.5 K,whose effect on the jet development can be ignored.The formed ice crystals almost do not disappear inside the computational domain because the increase rate of the particle sizes is far greater than the reduction rate in the computational domain.The particle size distribution develops from dispersion to concentration,finally presenting an approximately normal distribution,whose particle sizes are mainly concentrated in 0.8–2.0μm,accounting for approximately 83%of the particle total in the contrail,as the contrail shape develops in the computational domain from a ring shape to a pear shape,finally presenting a cone shape.
作者
曾培高
姜毅
杨哩娜
ZENG PeiGao;JIANG Yi;YANG LiNa(School of Aerospace Engineering,Beijing Institute of Technology,Beijing 100081,China)
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2022年第6期77-91,共15页
Scientia Sinica Physica,Mechanica & Astronomica
关键词
尾迹云
同轴喷管
求积矩方法
异质凝结
自由射流
contrail
coaxial nozzle
quadrature method of moments
heterogeneous condensation
free jet
作者简介
联系人:杨哩娜,E-mail:Yangln@bit.edu.cn。
