三面加热窄矩形通道内单汽泡生长过程可视化研究

Visualization Research of Single Bubble Growth Process in a Narrow Rectangular Channel Heated on Three Sides

本文以去离子水为工质,对三面加热窄矩形通道内单汽泡生长过程进行实验研究,利用可视化手段拍摄三面加热窄矩形通道内汽泡生长状态图像。通过汽泡周期曲线与图像进行对照,分析汽泡生长的物理过程及产生机理。实验过程中发现4种汽泡行为:窄矩形通道内窄边处汽泡分为浮升、聚合、连续性生长三大类,中间加热面仅观测到一类单汽泡快速生长。与传统单面加热面相比,窄边处的汽泡脱离直径更大,汽泡发生的变形更明显。本文重点分析了不同过冷度下汽泡的生长机理、影响因素、直径变化规律、以及汽泡脱离点。实验研究发现,在高过冷度下汽泡底部最先开始发生变形,在中过冷度下汽泡的底部和顶部都发生不同程度的变形,而在低过冷度下汽泡的生长形态保持一致。

In this paper, the grow process of single bubble in a narrow rectangular channel heated on three sides is experimentally investigated. Deionized water is used as working medium and the image of bubble growth state in the narrow rectangular channel heated on three sides is photographed by visualization method. By comparing the cycle curve of bubble with the image, the physical process and mechanism of the bubble growth are analyzed. Four kinds of bubble behaviors are found in the experiment: The bubbles at the narrow edge of the narrow rectangular channel can be divided into three states: buoyancy lift, coalescence and continuous growth. Single bubble is observed on the middle heating surface. Comparing with the bubbles on the traditional single-side heating surface, the departure diameter of bubble on the middle heating surface at the narrow edge is larger and the deformation of the bubble is more pronounced. In this paper, the growth mechanism, influencing factors, diameter variation law, and bubble detachment point of the bubbles under different supercooling are analyzed. The experimental results show that the deformation first begins at the bottom of bubbles under high subcooling, and the bottom and top of the bubbles are deformed to varying degrees under moderate undercooling but the growth pattern of bubbles remains the same under low undercooling.