液滴倾斜撞击液膜传热特性研究

doi:10.11949/0438-1157.20250408

摘要/Abstract

摘要：

利用超疏水导轨稳定生成了具有特定撞击角度的液滴，实验研究了液滴倾斜撞击液膜过程中的传热特性，并利用壁面冷却系数最大值及其标准差来综合评估整个观测区域的冷却效果。研究发现，壁面冷却过程可以划分为快速冷却阶段和恢复阶段，快速冷却阶段的时间尺度远小于恢复阶段。壁面冷却系数最大值和标准差的峰值随Weber数和撞击角度的增加而减小，随加热功率的增加而增加。在恢复阶段，同一时间的壁面冷却系数最大值和标准差随Weber数和撞击角度增加而减小，参数变化速率随加热功率增加而增加。

关键词: 液滴, 倾斜撞击, 液膜, 流动, 传热, 两相流

Abstract:

In industrial and agricultural settings, obliquely impacting droplets on a liquid film is a common phenomenon with significant scientific and practical importance. However, due to limitations in experimental techniques, the heat transfer characteristics associated with this oblique impact have not been systematically explored. In this study, we address this gap by employing a superhydrophobic guide rail to stably generate droplets at controlled impact angles, enabling a detailed experimental investigation into the heat transfer behavior of oblique droplet impact on a liquid film. The cooling performance across the observed region is quantitatively evaluated using the peak value and standard deviation of the wall cooling coefficient. The experimental results indicate that the wall cooling process can be divided into a rapid-cooling phase and a subsequent recovery phase, where the timescale of the former is much shorter than that of the latter. Both the peak value and standard deviation of the wall cooling coefficient decrease with increasing Weber number and impact angle, while they increase with higher heating power. During the recovery phase, at any given time, both parameters continue to decrease with larger Weber numbers and impact angles, and their rate of change grows more pronounced with increasing heating power.

Key words: droplet, oblique impact, liquid film, flow, heat transfer, two-phase flow

中图分类号:

TK 124

鲍民乐, 龚路远, 郭亚丽, 沈胜强. 液滴倾斜撞击液膜传热特性研究[J]. 化工学报, DOI: 10.11949/0438-1157.20250408.

Minle BAO, Luyuan GONG, Yali GUO, Shengqiang SHEN. Heat transfer characteristics of oblique droplet impact on liquid film[J]. CIESC Journal, DOI: 10.11949/0438-1157.20250408.

图/表 7

图1 实验平台的示意图

Fig.1 Schematic diagram of the experimental system

表1 实验参数的不确定度

Table 1 Uncertainty of experimental parameters

实验参数	测量方法	不确定度
液滴直径d_drop	图像分析法	± 2.7%
液滴撞击速度u_drop	图像分析法	± 1.9%
液滴撞击角度θ	图像分析法	± 3.3%
液膜厚度h	白光共焦位移传感器测量	± 1.5%
电压值U	直流电源读数	± 1.0%
电流值I	直流电源读数	± 2.0%
Weber数We	间接测量	± 4.7%
加热功率q_in	间接测量	± 2.2%
壁面冷却系数 η	间接测量	± 18.7%

图2 撞击冷却区随时间的演变及对应的液体流动状态

Fig. 2 Evolution of the impact cooling zone and the corresponding liquid flow state

图3 壁面冷却系数最大值和标准差随时间的变化

Fig. 3 Variation of the maximum and standard deviation of the wall cooling coefficient over time

图4 Weber数对壁面冷却系数最大值和标准差的影响

Fig. 4 Effect of Weber number on the maximum and standard deviation of the wall cooling coefficient

图5 撞击角度对壁面冷却系数最大值和标准差的影响

Fig. 5 Effect of impact angle on the maximum and standard deviation of the wall cooling coefficient

图6 加热功率对壁面冷却系数最大值和标准差的影响

Fig. 6 Effect of heating power on the maximum and standard deviation of the wall cooling coefficient

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