相邻离心式喷嘴液膜撞击雾化过程仿真

Simulation on Liquid Films Impact Atomization Process of Adjacent Pressure Swirl Injectors

关键词:  离心式喷嘴  锥形液膜撞击  雾化过程  数值仿真

Key words:  Pressure swirl injector  Conical liquid film impact  Atomization process  Numerical simulation

摘要:

基于Gerris软件建立的锥形液膜雾化破碎过程数值仿真方法，对相邻多个离心式喷嘴液膜撞击雾化过程进行了数值仿真，可视化展示了喷雾场三维形态和结构特征，并做了流场分析，讨论了喷嘴之间的相互干扰作用，获得了液滴空间分布，对相邻不同数目的喷嘴雾化效果进行了比较。结果表明:双喷嘴液膜撞击会形成一个类似互击式射流撞击形成的扇形区域，但又与其不同；锥形液膜的撞击效果主要依赖径向速度而不是切向速度，液滴平均粒径与撞击液膜间的旋向几乎无关。多喷嘴液膜撞击会使得液滴空间分布发生大的变化，液膜破碎长度会缩短。多喷嘴液膜撞击后的雾化特性是否改善与单喷嘴原先的雾化特性以及喷嘴间的距离密切相关。对于文中特定的喷嘴结构、喷嘴间距及排列方式，双喷嘴的液滴SMD均比单喷嘴的增大约4.8%～6.1%；四喷嘴的液滴SMD比单喷嘴的增大约7.3%，比双喷嘴的增大约2.4%。

Abstract:

Based on the numerical simulation method of conical liquid film atomization and breakup process established by Gerris，the atomization process of impact among liquid films formed by adjacent multiple pressure swirl injectors was simulated. The three-dimensional shape and structure characteristics were showed visually and were analyzed in the spray field. Besides，the interaction among the nozzles was discussed，and the spatial distribution of droplets was obtained statistically. The spray characteristics of films impact among the different number of nozzles were also compared. The results show that the films impact between two nozzles forms a fan-shaped region that is similar with the spray field of impinging jets injector，but both are not exactly same. The impact effects of conical liquid films are mainly determined by the radial velocity component of films rather than the tangential velocity component of ones，which also results in that the droplets average diameter almost has nothing to do with the rotation direction of impacting liquid films. The impact of liquid films among the adjacent multiple nozzles would make some remarkable changes to the spatial distribution of droplets，and the breakup length of liquid film is shortened. For the adjacent multiple nozzles，the improvement of atomization characteristics is closely associated with the single nozzle original atomization characteristics and the distance among nozzles. Ultimately，when the geometry structure of nozzles，the distance among nozzles and the position layout of nozzles were given in this article，the droplets SMD of the adjacent double nozzles is more than that of single nozzle，which increased by approximately 4.8%～6.1%. The droplets SMD of the adjacent four nozzles is about 7.3% larger than that of the single nozzle，and is about 2.4% larger than that of the double nozzles.