Structure of Reacting and Non-Reacting Swirling Air-Assisted Sprays

Abstract

A detailed characterization of a methanol spray produced by an air-assist atomizer with swirling atomizing air has been conducted. This study is the third of a series which examines the structure of sprays produced by a standardized atomizer which can be operated in three modes, pressure swirl, non-swirling air-assist, and swirling air-assist. Measurements of drop size and three components of velocity, three components of the gas phase velocity, the concentration of hydrocarbons within the spray, and time resolved droplet measurements are obtained at axial locations of 7·5, 15, 25, 35, 50, 75, and 100 mm. These measurements are obtained for both reacting and non-reacting cases. In addition, the atomizing air flow in the absence of the spray is characterized. Primary observations from the present study are that (1) the presence of the drops alters the structure of the gas phase turbulence, including the degree of isotropy, (2) the presence of reaction strongly impacts the axial and radial velocity components, while having little impact on the azimuthal component, (3) reaction reduces the mean diameter of the distributions at all locations. (4) a strong dependence of the axial and radial velocity upon drop size exists, whereas little dependency is observed for the azimuthal component, and (5) detailed examination of the droplet arrival indicates clustering of drops. Finally, it is observed that the findings from the present study both agree and contradict with the results of others. This is indicative of the inherent complexity of reacting sprays, and suggests that a more methodical approach to studying the impact of swirl and geometrical changes is required to understand the effects of atomizing air. swirl, vaporization, and phase interaction such as that undertaken in the present effort.

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Notes on contributors

M. ADACHI

Visiting Scientist, Horiba Ltd.