超声激励平板振型分布对液滴群去除特性影响

doi:10.11949/0438-1157.20251016

摘要/Abstract

摘要：

实验研究了超声激励平板振型分布对液滴群去除特性的影响。首先，基于超声扫频的平板表面铜粉分布结果表明，特定频率下各平板表面均会出现高-过渡-低振幅交替的半谐振特征，方、矩、圆、椭四种平板的低振幅区域分别呈中心对称4D型、轴对称4弧型、同心2圆型、中心对称4弧型分布。其次，在特定半谐振频率下针对各平板开展液滴群去除实验，发现液滴群均经历铺展雾化、运动合并、回落凝结、二次雾化四个阶段后，以微液滴形式残留且形状与各平板低振幅区域一致。再次，定量分析了超声振幅对各平板液滴去除特征的影响，结果表明随振幅增大，方、矩、圆三种平板离中心较近的微液滴残留区宽度单调递减，椭圆板液滴残留区则无明显变化规律；各振幅下椭圆板的微液滴残留区面积占比均最小，40%振幅下椭板比方、圆、矩板残留区域占比分别小17.59%、14.32%、6.98%，表明有多个焦点的平板形状可能更利于液滴群去除。预期本文结果将丰富超声波除液滴以及热泵空调增效领域的研究。

关键词: 超声波, 液滴群, 雾化, 聚结, 蒸发, 表面

Abstract:

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 showed distinct spatial patterns,namely a centrally symmetric four-D type, an axially symmetric four-arc type, a concentric double-ring type, and a centrally symmetric four-arc type, respectively. Droplet group removal experiments were performed for each plate at its specific semi-resonant frequency. It was found that after the droplet group went through four stages, namely spreading and atomizing, moving and merging, falling and condensing, and secondary atomizing, it remained in the form of microdroplets with a shape consistent with the low amplitude region 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. These findings provide new insights into ultrasonic droplet removal mechanisms and may offer valuable guidance for efficiency enhancement in heat pump air-conditioning systems.

Key words: ultrasound, droplets, atomization, coalescence, evaporation, surface

中图分类号:

TN 752.6

赵日晶, 谢锃, 许桐瑞, 吴永帅, 黄东, 姜学斌. 超声激励平板振型分布对液滴群去除特性影响[J]. 化工学报, DOI: 10.11949/0438-1157.20251016.

Rijing ZHAO, Zeng XIE, Tongrui XU, Yongshuai WU, Dong HUANG, Xuebin JIANG. Effect of ultrasonic excitation vibration mode distribution of plates on droplet group removal characteristics[J]. CIESC Journal, DOI: 10.11949/0438-1157.20251016.

图/表 10

图1 超声激励平板振动特性和液滴群去除实验台

Fig.1 Ultrasonic excitation plate vibration characteristics and droplet group removal test platform

图2 四种形状平板结构

Fig.2 Four shapes of flat plate structures

图3 接触式超声激励下平板表面振动类型

Fig.3 Vibration types of plate surface under contact ultrasonic excitation

图4 不同超声振幅激励下方形板表面滴定液滴群去除特性

Fig.4 Removal characteristics of titration droplet groups on square plate surface under different ultrasonic amplitude excitations

图5 不同超声振幅下方形板液滴去除各阶段时间分布

Fig5 Time distribution of each stage of droplet removal on a square plate under different ultrasonic amplitudes

图6 方形板超声雾化2s后液滴残留区位置及宽度分布

Fig.6 Position and width distribution of the droplet residual area after 2s of ultrasonic atomization on a square plate

图7 矩形板超声雾化2s后液滴残留区位置及宽度分布

Fig.7 Position and width distribution of droplet residual area after 2s of ultrasonic atomization on a rectangular plate

图8 圆形板超声雾化2s后液滴残留区位置及宽度分布

Fig.8 Position and width distribution of droplet residual area after 2s of ultrasonic atomization on a circular plate

图9 椭圆形板超声雾化2s后液滴残留区位置及宽度分布

Fig.9 Position and width distribution of the droplet residual area after 2s of ultrasonic atomization on an elliptical plate

表1 不同振幅下超声激励四种平板后的液滴残留面积占比

Table 1 Residual area fraction after ultrasonic excitation of four types of plates under different amplitudes

	10%	20%	30%	40%
方形板	-	41.30%	34.38%	28.90%
矩形板	-	39.34%	24.14%	18.28%
圆形板	-	-	27.67%	25.63%
椭圆形板	13.30%	13.33%	12.27%	11.30%

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