低Weber数射流撞击雾化的数学模型

通过分析低Weber数无粘射流撞击形成液膜雾化的特征, 由质量守恒和动量守恒, 并借鉴前人的理论和实验结果, 推导出Taylor心形波作用下计算液膜厚度和形状的近似解析式, 数值计算结果与文献所给实验数据基本吻合一致。结合矩形喷孔形成的扇形液膜的破碎理论, 进一步计算了不同撞击角下雾化形成液滴尺寸的大小及分布。 

A METHEMATICAL MODEL OF IMPINGING JETS ATOMIZATION AT LOW WEBER NUMBER

The characteristics of the spray produced by impinging jets atomization is theoretically analyzed.Depending on Weber number,two breakup regimes of sheet are considered with transition occurring at Weber numbers between 500 and 2000.In the low Weber number regime ( We ≤2000),the sheet breakup is due to Taylor cardioidal waves.While in the high Weber number regimes,the sheet disintegration is caused by growth of Kelvin-Helmholtz instability waves.The model uses an analogy with the oblique impact of a liquid jet on a wall.At Weber number less than 2000,mathematical expressions to predict the sheet thickness and shape during formation of nonviscous liquid sheet are derived from mass conservation and momentum conservation equations by reference to theoretical results and empirical correlations reported in the literature.The numerical results are in good agreement with experimental data available in the literature.Predictions of the spray droplet size and distribution formed by the disintegration of the viscous liquid sheets are also obtained by use of the mathematical formulation developed for fan spray injectors.This model can be used to estimate the size range and distribution of droplets formed by impinging jets atomization in quasi static surroundings.