Abstract
Effervescent atomization is one of the twin-fluid atomization methods while it has better performance in terms of smaller drop sizes and/or lower injection pressures. In order to investigate the effects of the internal flow patterns on droplet characteristics, a new kind of effervescent atomizer was designed and manufactured. The bubble forming process was visualized with a high-speed camera, while the droplet size was characterized with a LDV/PDA system. The experimental results show that there are three regimes of the two-phase flows inside the discharge orifice, one is bubbly flow, another is annular flow while the other is the intermittent flow. The flow patterns transfered from bubbly flow to intermittent flow and then to annular flow with decreasing of the water flow rate. In addition, with increasing of the working pressure or decreasing of the water flow rate, the SMD (Sauter mean diameter) of the droplets decreased and the axial mean velocity increased.
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Abbreviations
- A :
-
cross-sectional area of the mixing tube, m2
- d :
-
inside diameter of the mixing tube, m
- GLR:
-
gas to liquid mass flow-rate ratio, dimensionless
- j :
-
superficial velocity (the volumetric flow rate of fluid moving through a pipe
- M :
-
flow rate, kg/s
- P :
-
pressure, Pa
- SMD:
-
Sauter mean diameter, m
- t :
-
bubble development time, s
- t * :
-
normalized bubble development time, dimensionless
- v :
-
velocity, m/s
- v * :
-
normalized velocity, dimensionless
- ρ:
-
density, kg/m3
- τ:
-
periodicity, s
- τ* :
-
normalized periodicity, dimensionless
- B :
-
bubble
- g :
-
gas
- l :
-
liquid
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This work was partially presented on the 9th Asian Symposium on Visualization, Hong Kong, 4–8 June, 2007.
Huang Xin: He received his PhD. in 2007 from State Key Lab. of Fire Science, University of Science & Technology of China. He is currently an assistant professor of the Tianjin Fire Research Institute, the Ministry of Public Security of China. His research interests are modeling and experimental study on water mist fire suppression.
Wang Xishi: He received his M.Sc. degree in 1997 from Anhui Institute of Optic & Fine Mechanics of Chinese Academia Sinica and his PhD. in 2002 from University of Science & Technology of China. At the end of 2002, he worked at the Department of Chemical System Engineering of the University of Tokyo for 3 months as a visiting scientist. During 2003 to 2005, he worked as a postdoctor at the Department of
Mechanical Engineering of the Hong Kong University of Science & Technology. He is currently an associate professor of the State Key Lab. of Fire Science, University of Science & Technology of China. His current research focus on two/multi phase flows, laser based diagnostic techniques, fire suppression mechanisms and technologies.
Liao Guangxuan: He is currently a professor and executive director of the State Key Lab. of Fire Science, University of Science & Technology of China. His research interests include fire safety science and technology, simulation of fire process, fire suppression and extinction mechanisms by water mist, diagnostics of combustion flow field.
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Huang, X., Wang, X. & Liao, G. Visualization of two phase flow inside an effervescent atomizer. J Vis 11, 299–308 (2008). https://doi.org/10.1007/BF03182198
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DOI: https://doi.org/10.1007/BF03182198