Effect of Turbulence on Spatial Distribution and Group Behavior of Droplet in a Spray Flame

Abstract

This paper presents results of the study on the effect of turbulence on droplet dispersion and group behavior in liquid-fuel spray flame. Insertion of grids with different mesh sizes in front of the nozzle resulted in change of turbulence intensity, while the change of turbulence integral scale was negligible. For smaller mesh and lower turbulence intensity total vaporization rate is rapidly increasing, while the droplet size distribution remains practically unchanged. Measurements of combustion group number showed that decrease of average group combustion number is well correlated with increase of vaporization rate. Therefore, the reason for observed vaporization enhancement, could be explained by more uniform spatial distribution and weaker inter-droplet interactions, which usually strongly reduce vaporization rate of droplets in dense sprays. Contrary to observed increase of vaporization rate, flame length is growing. This phenomenon is attributed to reduction of mixing of evaporated fuel and ambient air for lower turbulence intensity and poorer mixing between two gaseous phases compared to mixing between the air and droplets in liquid phase.

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Notes on contributors

RAFAL J. SORNEK

Corresponding author: Rafal SORNEK, Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-8656 Tokyo, JAPAN. TEL: [phone], FAX: [phone],e-mail: [email protected]