超声速气流中液体横向射流雾化破碎模型改进

Modification of Atomization Breakup Model for Liquid Jet into Supersonic Crossflow

关键词:  横向射流  二次破碎  线性不稳定性  雾化  KH/RT模型

Key words:  Jet into crossflow  Secondary breakup  Linear instability  Atomization  KH/RT model

摘要:

为研究超声速气流中液体横向射流的雾化过程，根据可压缩条件下线性稳定性分析解推导出的不稳定增长率和波数间的色散关系，对KH/RT模型进行了改进，并调整了离散相液滴的追踪算法，利用改进的KH/RT模型对1.94Ma气流条件下水横向射流过程进行模拟。研究表明，数值模拟中液滴的实际追踪数对计算结果有较大影响，而改进的液滴追踪算法有效增加了液滴数，提高了计算准确性；改进的KH/RT模型扩大了Weber数的适用上限至4000，可用于超声速流场；利用改进的KH/RT破碎模型得到的液雾穿透深度与试验测量结果基本一致，而液雾展向和近壁区的分布与试验有一定差异。

Abstract:

In order to study the atomization process of liquid jet into supersonic crossflow，the original KH/RT model was improved，which was based on the dispersion relation between the unstable growth rate and wave number，according to the compressible linear stability analysis theory. And the tracking algorithm of the dispersed phase droplets was also modified to adjust the supersonic condition. The modified KH/RT model was used to simulate the atomization process of liquid jet into a 1.94 Mach supersonic crossflow. The obtained results indicate that，the tracking number of the droplets in simulation has a great influence on the results，and the new droplet tracking algorithm improves the calculation accuracy，by increasing the tracking number of droplets. Besides，the improved KH/RT model expands the upper limit of liquid Weber number to 4000，which makes the model more suitable for supersonic flow. The liquid penetration height obtained by the modified KH/RT model matches experimental measurement well; however，there is still some difference in the spanwise direction and the near wall region of particles distribution.