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ICLASS 94<br>Proceedings of the Sixth International Conference on Liquid Atomization and Spray Systems

ISBN:
978-1-56700-019-1 (Print)
978-1-56700-445-5 (Online)

RELATION OF SPRAY STRUCTURE AND TURBULENCE OF AIR WITHIN SPRAY EJECTED FROM INTERNAL MIXING TWIN FLUID ATOMIZER OF ORIFICE-TYPE

Takashi Sakai
Department of Bio-Chemical Engineering, Gunma University, Kiryu, Gunma, Japan

D. Q. Zhao
Department of Chemical Engineering, Nanjing Institute of Chemical Technology, Nanjing, P. R. China

M. Iijima
Department of Bio-Chemical Engineering, Gunma University, Gunma, Japan

Masahiro Saito
Department of Mechanical System Engineering, Gunma University, Kiryu, Gunma, Japan

Abstract

The role of turbulence of air on the disintegration of two-phase jets ejected from a twin-fluid atomizer of internal mixing type with orifice, TFA-IM-O, was studied experimentally. The relationship between mixing and flow patterns in the mixing chamber and atomization patterns of the ejected two-phase jets were observed and it was found that complete mixing of air and liquid within the mixing chamber generated fine atomization. The structure of TFA-IM-O spray was studied using a PDP A and novel characteristics of this spray were defined. The central zone was filled with finer droplets of dense flux and the outer zone was coarse and sparse. Change of the drop mean diameters and numbers from near the nozzle port toward downstream was analyzed and it was found that the most intense disintegration of liquid occured near the nozzle port around the axial zone within two-phase jets.
Turbulent flow characteristics of air within air jets and spray jets issued from TFA-IM-O were measured by LDV and compared with that from a circular tube, CT. It was found that the turbulent intensity of TFA-IM-O immediately after ejection was greater than about six times that from CT.
From the experimental results, it was considered that the turbulence of air within two-phase jets which came from turbulent mixing within the mixing chamber, would promote liquid disintegration at the inside zone of spray jets by Reynolds stress, though disintegration by relative velocity proceeds at the outer zone.