Purpose

The purpose of this study is to investigate the effect of the injection angle α on the spray structures of an air-blast atomizer and help enhance the understanding of droplet-gas mixing process in such atomizers in the engineering domain.

Design/methodology/approach

The phenomena in the air-blast atomizer were numerically modelled using the computational fluid dynamics software Fluent 17.2. The Euler-Lagrange approach was applied to model the droplet tracking and droplet-gas interaction in studied cases. The standard k-ε model was used to simulate the turbulent flow. A model with a modified drag coefficient was used to consider the effects of the bending of the liquid column and its penetration in the primary breakup region. The Kelvin-Helmholtz, Rayleigh-Taylor model was applied to consider the secondary breakup of the droplets.

Findings

The basic spatial distribution and spray structures of the droplets corresponding to the angled liquid jet (α = 60°) were similar to those reported in liquid jets injected transversely into a gaseous crossflow studies. The injection angle α did not considerably influence the averaged Sauter to mean diameter (SMD) of the cross-sections. However, the spray structures pertaining to α = 30°, α = 60° and α = 90° were considerably different. In the case of the atomizer with multiple injections, a “collision region” was observed at α = 60° and characterized by a higher ci and larger averaged SMD in the central parts of the cross-sections.

Originality/value

The injection angle α is a key design parameter for air-blast atomizers. The findings of this study can help enhance the understanding of the droplet-gas mixing process in air-blast atomizers. Engineers who design air-blast atomizers and face new challenges in the process can refer to the presented findings to obtain the desired atomization performance. The code has been validated and can be used in the engineering design process of the gas-liquid jet atomizer.

中文翻译：

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喷射角度对鼓风雾化器喷雾结构影响的数值研究

目的

本研究的目的是研究喷射角 α 对鼓风雾化器喷雾结构的影响，并有助于提高工程领域对此类雾化器中液滴-气体混合过程的理解。

设计/方法/方法

使用计算流体动力学软件 Fluent 17.2 对鼓风雾化器中的现象进行了数值模拟。欧拉-拉格朗日方法用于模拟研究案例中的液滴跟踪和液滴-气体相互作用。标准 k-ε 模型用于模拟湍流。使用修正阻力系数的模型来考虑液柱弯曲及其在初级破碎区的渗透的影响。应用 Kelvin-Helmholtz、Rayleigh-Taylor 模型来考虑液滴的二次破碎。

发现

与成角度的液体射流 ( α = 60°)相对应的液滴的基本空间分布和喷雾结构与横向注入气体横流研究中的液体射流中报道的相似。注入角α对横截面的平均索特平均直径 (SMD) 没有显着影响。然而，与α = 30°、α = 60°和α = 90°有关的喷雾结构有很大不同。在具有多次喷射的雾化器的情况下，在α = 60°处观察到“碰撞区域” ，其特征在于横截面中心部分的较高 ci 和较大的平均 SMD。

原创性/价值

喷射角α是鼓风雾化器的关键设计参数。这项研究的结果有助于加深对鼓风雾化器中液滴-气体混合过程的理解。设计鼓风雾化器并在此过程中面临新挑战的工程师可以参考所呈现的发现来获得所需的雾化性能。该代码已经过验证，可用于气液喷射雾化器的工程设计过程。