基于动态识别柴油喷雾破碎特征的ELSA改进算法

Dynamic Identification of Diesel Spray Breakup Model Feature Based on Improved ELSA Algorithm

欧拉-拉格朗日实时耦合的喷雾(ELSA)方法是雾化破碎的前沿算法,其中模型转换是该方法的关键技术之一;作为ELSA转换研究中常用的固定网格分区方法,需要根据试验来确定近场稠密区与远场边界的位置,以及作为改进而采用的液滴距离以及液相体积比等方法来实现动态ELSA转换.在现有的ELSA转化研究基础上,笔者对在液柱前锋液膜破碎时产生的欧拉液相团块进行动态捕捉,以球形度与粒子直径为判据,将符合条件的液相团块转化为拉格朗日粒子,获得了完整的液柱、一次破碎以及二次破碎过程,结果表明:初始液滴来自液膜破碎过程,以球形度与粒子直径为判据的ELSA方法能够在保证喷雾仿真精度前提下精确地模拟液柱破碎为液滴的过程.

The Euler-Lagrangian spray and atomization(ELSA)method is currently the leading edge algorithm for atomization and fragmentation,and the model conversion is one of the key techniques.In the current ELSA model,model transformation is based on dividing the mesh into fixed areas.This method needs to determine the position of near-field dense area and far-field boundary according to the experimental results.As an improvement,there is a dynamic transformation criterion based on the droplet distance and liquid-phase volume ratio.Base on the existing ELSA transformation thought,We dynamically captures the Euler liquid mass produced when the liquid film at the front of the liquid column breaks,and takes the sphericity and particle diameter as the criteria to convert the qualified liquid mass into Lagrangian particles,and obtains the complete process of liquid column,primary breaking and secondary breaking.The results show that the initial droplet comes from the liquid membrane crushing process.The ELSA method based on the criterion of sphericity and particle diameter can simulate the process of liquid column crushing to droplet more accurately under the premise of ensuring the accuracy of spray simulation.