Visualization of Two Phase Flow inside an Effervescent Atomizer

Article type: Research Article

Authors: Huang, X.^; | Wang, X. | Liao, G.

Affiliations: State Key Lab. of Fire Science, University of Science and Technology of China, Hefei, 230026, P. R. China. E-mail: wxs@ustc.edu.cn | Tianjin Fire Research Institute, the Ministry of Public Security, Tianjin, 300381, P. R. China

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.

Keywords: Visualization, Water mist, Effervescent atomization, Two phase flow

Journal: Journal of Visualization, vol. 11, no. 4, pp. 299-308, 2008