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首页> 外文期刊>Journal of Heat Transfer >Dynamics of Bubble Motion and Bubble Top Jet Flows From Moving Vapor Bubbles on Microwires
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Dynamics of Bubble Motion and Bubble Top Jet Flows From Moving Vapor Bubbles on Microwires

机译：在微丝上移动蒸气气泡产生的气泡运动和气泡顶部喷射流的动力学

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摘要

Rapid bubble sweeping along heated wires was observed during subcooled nucleate boiling experiments on very fine wires with jet flows emanating from the tops of the vapor bubbles for a variety of conditions. This paper presents experimental results with a numerical analysis of the physical mechanisms causing the experimentally observed bubble motion and jet flows. The results show that the moving bubble creates a nonuniform temperature distribution in the wire by cooling the wire as it moves along the wire with significant heat transfer in the wake behind the bubble. The results verify that the bubble motion is driven by the temperature difference from the front to the back of the bubble, which causes Marangoni flow. The Marangoni flow then thrusts the bubble forward along the wire with the calculated bubble velocities agreeing well with experimental measurements. In addition, the temperature difference from the bottom to the top of the bubble creates a vertical component to the Marangoni flow that results in the jet flows from the bubble tops. Comparisons with experimental observations suggest that the condensation heat transfer at the bubble interface is restricted by noncondensable gases that increase the surface temperature gradient and the resulting Marangoni flow. The numerical results also show that the heat transfer from the wire due to the Marangoni flow is significantly larger than the heat transfer due to the evaporation under the bubble.
机译：在非常细的金属丝上进行过冷的核沸腾实验期间，观察到了沿加热丝的快速气泡扫掠，在各种条件下，气泡都从气泡的顶部散发出来。本文通过对引起实验观察到的气泡运动和射流的物理机理进行数值分析，给出了实验结果。结果表明，移动的气泡通过冷却金属丝沿金属丝移动时在金属丝中产生不均匀的温度分布，从而在气泡后面的尾流中产生明显的热传递。结果验证了气泡运动是由气泡前后之间的温差驱动的，这导致了Marangoni流动。然后，Marangoni流动将气泡沿金属丝向前推，计算出的气泡速度与实验测量值非常吻合。此外，气泡底部到顶部的温差会产生与Marangoni流垂直的分量，从而导致从气泡顶部流出的射流。与实验观察结果的比较表明，气泡界面处的冷凝传热受到不可冷凝气体的限制，这些不冷凝气体会增加表面温度梯度和所产生的Marangoni流量。数值结果还表明，由于Marangoni流动而引起的来自金属丝的传热明显大于由于气泡下的蒸发而产生的传热。

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