液体雾化效果的检测及流体力学模拟

Acoustic emission detection and CFD simulation of a liquid spray process

为获得一种快速灵敏的液体雾化效果检测方法,利用置于挡板后方的声发射传感器,采集液体喷雾撞击挡板产生的声信号并进行多次扫描累加的快速傅里叶变换,得到不同流量下的声能量值和功率谱图.通过对实验结果的分析,提出临界良好雾化状态的声能量判据,即随着流量的增加,当液滴撞击挡板产生的声能量趋于平稳并开始缓慢上升,雾化准数由缓慢增加转变为迅速增大以及声能量均方差开始上升并趋于平稳时,液体喷雾处于良好雾化的临界状态,进一步增大流量,雾化效果的提升不明显.同时,对雾化效果采用摄像法测定和基于Eulerian-La-grangian耦合算法的计算流体力学(CFD)模拟,结果与声发射实验的结果吻合很好,由此说明采用声发射方法对液体雾化效果进行定性检测具有较强的可行性与准确性.

In order to acquire a fast and sensitive detecting method of liquid spray performance,the acoustic emission（AE） signals originated from impact of liquid spray on the baffle were collected by the transducer located behind the baffle,and processed by multiple scanning accumulated Fast Fourier Transform.By analyzing the acoustic energy and power spectrum,a new criterion to determine the critical state in which the atomization performance became satisfied was proposed.When acoustic energy variation tended to be stable and began to rise,and the atomization dimensionless number started to grow rapidly,meanwhile the mean square deviation of acoustic energy began to ascend and become stable as the liquid flow rate increased,the liquid spray achieved the critical state of excellent atomization.After that,the improvement of atomization performance would be unconspicuous if the liquid flow rate increased further.Simultaneously,the liquid spray process was detected through image pickup and calculated by Eulerian-Lagrangian computational fluid dynamics（CFD） simulation method.The criterion was verified by the images of spray field and the simulation results,which indicated the acoustic emission detection could measure the liquid spray performance qualitatively.