Jet flows from bubbles during subcooled pool boiling on micro wires
An experimental investigation was conducted on subcooled nucleate boiling on ultra-small wires having diameters of 25―100 m. High-speed photography and laser PIV (Particle Image Velocimetry) technology were used to visually observe the bubble dynamics. For highly subcooled boiling at moderate heat fluxes, the bubbles generally remained attached to the micro heating wires and bubble-top jet flows were clearly observed. Smaller bubbles usually had stronger bubble-top jet flows, while larger bubbles seemed to produce multi-jet flows. The structures of the bubble-top jet flows, as well as multi-jet flows, were proposed from the experimental observation. A model was developed to describe jet flow phenomena from bubbles on micro wires. Numerical simulations for bubbles having diameter of 0.03 and 0.06 mm showed that both the bubble-top and multi-jet flows were induced by a strong Marangoni effect due to high temperature gradients near the wire. The predicted velocity magnitudes and flow structures agreed very well with experimental measurements. The bubble size relative to the wire is an important factor affecting the jet flow structure. For a 0.03 mm bubble on a 0.1 mm wire, only a bubble-top jet flow forms, while a complex multi-jet flow pattern forms around the bubble with a weak bubble-top jet and two side jet flows for a 0.06 mm bubble.
作 者： WANG Hao D.M.Christopher PENG Xiaofeng WANG Buxuan 作者单位： Laboratory of Phase Change and Interfacial Transport Phenomena, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China 刊 名： 中国科学E辑（英文版） SCI 英文刊名： SCIENCE IN CHINA SERIES E ENGINEERING & MATERIALS SCIENCE 年，卷(期)： 2005 48(4) 分类号： Q94 关键词： subcooled boiling bubble multi-jet jet flow PIV Marangoni CFD