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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)

THE ROLE OF ORIFICE FLOW PATTERN IN FUEL ATOMIZATION

Zhen Huang
Key Laboratory of Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Minhang District, 200240 Shanghai, People's Republic of China

Y.M. Shao
Chongqing Institute of Communications, Chongqing, PR China

Siichi Shiga
Department of Mechanical Engineering, Faculty of Engineering, Gunma University, Gunma, Japan

Hisao Nakamura
Department of Mechanical Engineering, Faculty of Engineering, Gunma University, Gunma, Japan

Takao Karasawa
Department of Mechanical Engineering, Faculty of Engineering, Gunma University, Gunma, Japan

Abstract

In order to develop a better understanding of the controlling mechanism of fuel atomization, an investigation was carried out to evaluate orifice flow pattern and its effect on fuel atomization. Experiments were performed under atmospheric conditions on scaled−up model nozzles and metal nozzles with different orifice entrance configuration and nozzle L/D ratio. The orifice flow pattern and the jet appearance were observed by photographic technique and the Sauter mean diameter was measured by light scattering technique. It was found that the orifice flow, which usually exhibits two characteristic patterns, the flow with contraction and reattachment, and the flow free from the wall, will lead to distinct jet appearances near the nozzle exit. For a certain injection velocity at the nozzle exit, the pattern with flow contraction and reattachment will yield smaller droplet size than the pattern with flow free from the wall. The orifice flow pattern and the injection velocity at the nozzle exit are two predominant factors in the fuel atomization.