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Flow Structures Around Micro-bubbles During Subcooled Nucleate Boiling |
| WANG Hao;PENG Xiao-Feng;David M. Christopher;WANG Bu-Xuan |
| Laboratory of Phase Change and Interfacial Transport Phenomena, Department of Thermal Engineering, Tsinghua University, Beijing 100084 |
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| Cite this article: |
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WANG Hao, PENG Xiao-Feng, David M. Christopher et al 2005 Chin. Phys. Lett. 22 154-157 |
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Abstract The flow structures were investigated around micro bubbles on extremely thin wires during subcooled nucleate boiling. Jet flows emanating from the bubbles were observed visually with the fluid field measurement using high-speed photography and a PIV system. The jet flows induced a strong pumping effect around a bubble. The multi-jet structure was further observed experimentally, indicating the evolution of flow structure around micro bubbles. Numerical simulations explore that the jet flows were induced by a strong Marangoni effect due to high temperature gradients near the wire. The bubble interface with multi-jet structure has abnormal temperature distribution such that the coolest parts were observed at two sides of a bubble extending into the subcooled bulk liquid rather than at the top. Evaporation and condensation on the bubble interface play important roles not only in controlling the intensity of the jet flow, but also in bringing out the multi-jet structure.
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| Keywords:
47.55.Dz
44.90.+c
47.20.Dr
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Published: 01 January 2005
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