超声激励平板振型分布对液滴群去除特性影响OA

An experimental study was conducted to investigate the effect of ultrasonic excitation mode shapes on the droplet group removal characteristics of flat plates.Based on the distribution of copper powder on the plate surfaces during ultrasonic frequency sweeping,it was found that all plates exhibited a semi-resonant vibration pattern characterized by alternating high-transition-low amplitude regions at specific frequencies.The low-amplitude regions of the square,rectangular,circular,and elliptical plates were distributed in a centrally symmetric 4D pattern,an axisymmetric 4-arc pattern,a concentric 2-circle pattern,and a centrally symmetric 4-arc pattern,respectively.Droplet group removal experiments were performed for each plate at its specific semi-resonant frequency.It was found that the droplet swarms underwent four stages:spreading and atomization,movement and merging,falling and condensing,and secondary atomization,before remaining as microdroplets with shapes consistent with the low-amplitude regions of each plate.A quantitative analysis of the effect of ultrasonic amplitude revealed that with increasing amplitude,the width of the residual microdroplet zones near the plate center decreased monotonically for the square,rectangular,and circular plates,while the elliptical plate showed no distinct trend.At all tested amplitudes,the elliptical plate exhibited the smallest residual area fraction of microdroplets.At 40％of the maximum excitation amplitude,its residual area fraction was 17.59％,14.32％,and 6.98％lower than those of the square,circular,and rectangular plates,respectively.This suggests that the shape of a flat plate with multiple foci may be more favorable for droplet group removal.