Experimental study on bubble behaviors in microgravity pool boiling
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摘要: 采用图像分析方法，对实践十号返回式科学实验卫星沸腾气泡实验项目获得的微重力单气泡过冷沸腾实验图像进行研究，提取并分析了微重力条件下单个气泡的生长过程.实验中观察到气泡激发形成、稳定黏附生长和滑移三个阶段，其中气泡稳定黏附生长又可分为底部扩张与回退两个子阶段.在气泡稳定黏附生长的底部扩张子阶段，气泡半径可以表示为时间的指数函数，时间指数从初期小气泡时的0.42减小到中期的0.28，最终趋于0.气泡尺寸在气泡底部收缩之初略有回调，随后再次缓慢增大，直到过冷液体完全侵入气泡底部，使气泡与加热面脱离，并在外界扰动作用下在加热面上滑移.相关数据可以作为沸腾现象中气泡热动力学分析的依据.Abstract: In this paper, the image analysis method is used to study the experimental data of the single bubble subcooled boiling experiment aboard the Chinese recoverable satellite SJ-10. The growth process of single vapor bubble in microgravity is extracted and analyzed. The bubble formation by the pulse excitation, steady growth of the bubble adhering to the excitation point, and its sliding over the heating surface are observed. Among the above three stages, the stage of steady growth of the bubble adhering to the excitation point can be divided into two sub-stages, i.e. expansion and retreat of the bubble base. During the bubble base expansion sub-stage, its radius can be expressed as an exponential function of time. The exponent decreases from 0.42 for the smaller size to 0.28 for the medium one, and finally to 0. The bubble size slightly retraces at the beginning of the bubble base retreat, and then slowly increases again until the subcooled liquid penetrated the bottom of the bubble completely, causing the bubble to detach from the heating surface and then slid on the heating surface under the external disturbance. The results can be used as the basis for the analysis of bubble thermal dynamics in boiling phenomena.
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Key words:
- Microgravity /
- Single bubble boiling /
- Bubble thermal dynamics
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