横向射流中煤油雾化特性的数值研究

Numerical Study on Spray Characteristics of Kerosene Jet in a Crossflow

关键词:  一次雾化  二次雾化  射流轨迹  索泰尔平均直径  动态自适应网格  煤油雾化

Key words:  Primary breakup  Secondary breakup  Jet trajectory  SMD  Adaptive mesh refinement  Kerosene atomization

摘要:

为了研究燃油射流雾化过程中的破碎形态及发展轨迹，实现燃油雾化过程的精确数值仿真，本文对直射式喷嘴喷入横向气流中的雾化特性进行数值模拟。计算采用耦合的多相流模型VOF和离散相模型DPM，研究煤油的一次雾化中射流破碎形态及发展过程，二次雾化过程中油滴的索泰尔平均直径（SMD）空间分布特性。应用动态网格自适应技术，精确捕捉到液体结构和射流表面的波动。数值计算结果表明，射流破碎过程中主要发生的是液柱破碎和表面剪切破碎；韦伯数对破碎模态的影响较大，液-气动量比对射流轨迹影响较大；在不同气动进口条件下，燃油射流轨迹以及液滴空间分布特性与经典经验关系式以及试验数据具有较好的一致性。

Abstract:

In order to study the fragmentation shape and development track of fuel jet atomization process， and realize the accurate numerical simulation of fuel atomization process， atomization characteristics of a direct jet in a cross flow were numerically investigated. A couped Volume-of-Fluid （VOF） and discrete phase model （DPM） method was adopted to study the deformation and development of jet in the process of primary breakup， and to track the spatial distribution characteristics of Sauter mean diameter （SMD） of fuel droplets in the process of secondary. The adaptive mesh refinement （AMR） technique was applied to accurately capture the liquid structures and wave behaviour on liquid surface. The numerical results show as follows：column breakup and surface shearing breakup are dominant in primary breakup process of liquid jet. Breakup modes are highly influenced by Weber number， and the jet trajectory is obviously affected by the momentum ratio of liquid to gas. The fuel jet trajectory and droplet spatial distribution are in good agreement with the classical empirical relations and experimental data under different aerodynamic inlet conditions.