采用商业软件Fluent对燃油直接喷射入横向气流中的破碎雾化过程进行数值模拟,选用欧拉-欧拉方法中的VOF(volume of fluid)耦合level-set方法模拟气液两相流动.数值模拟了横向气流中燃油直接喷射射流破碎雾化过程及其相应流场信息,分析了流场结构对液柱破碎雾化过程的影响,获得了横向气流中射流破碎点位置以及射流穿透深度,并与试验数据进行了对比.数值计算结果表明:①采用VOF耦合level-set算法能够较好地模拟射流喷入横向气流中燃油破碎雾化过程;②由于反向旋转的涡对的存在,使得液膜和液滴沿着展向(y向)输运,对于液滴的二次雾化起到促进作用;③射流液柱总是在喷嘴下游约8倍直径处开始破碎,且破碎点位置取决于喷嘴几何特性.
Abstract
In order to investigate the atomization process of a liquid jet injected into a crossflow
the Euler-Euler method in Fluent was used by numerical simulation. The VOF (volume of fluid) model coupled with level-set method was applied to simulate two-phase flow
and the numerical results showed the atomization process of liquid jet in crossflow and the flow field. The effects of flow fields on atomization process of a jet liquid column were studied. Breakup point and liquid jet penetration depth were gained and also compared with the experimental data. The numerical results show that:(1) The coupled level-set and VOF model can be used to simulate the atomization processes of liquid jet injected into crossflow.(2) Because of the counter-rotating vortex
the liquid film and the droplets are transported along the development direction (y)
playing a promoting role for secondary atomization. (3) The jet liquid column is always broken at about 8 times the diameter of the injector
and the location of the broken point is determined by the geometrical characteristics of the injector.