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Journal of Flow Visualization and Image Processing

ISSN Print: 1065-3090
ISSN Online: 1940-4336

Journal of Flow Visualization and Image Processing

DOI: 10.1615/JFlowVisImageProc.2014011273
pages 47-64

EVALUATION OF A LIQUID JET FLOW BY MEANS OF IMAGE ANALYSIS

Daisuke Akayama
Graduate School of Maritime Sciences, Kobe University, Japan
Shigeru Nishio
Graduate School of Maritime Sciences, Kobe University, 5-1-1, Fukaeminami, Higashinada, Kobe 658-0022, Japan
Akira Sou
Graduate School of Maritime Sciences, Kobe University, 5-1-1, Fukaeminami, Higashinada, Kobe 658-0022, Japan

ABSTRACT

The correlation between the development of atomization and flow field in a liquid jet was investigated. A fuel injector is widely used for internal combustion engines, and injection with high-quality atomization is vital for better thermal efficiencies. The present study aims at establishing a research approach for finding the fundamental mechanism of atomization enhancement. A simple two-dimensional nozzle was designed and a liquid jet flow was visualized by using a high-speed camera system. An evaluation index of atomization by means of image analysis was proposed. The proposed approach is based on an idea that the essence of atomization in fuel injection will be the ratio between the surface area and the volume of a fuel. The evaluation index enables us to know the degree of atomization quantitatively, so that the procedure of atomization enhancement has been clarified. The velocity field was obtained by applying the PIV analysis to a visualized image, and the correlation with atomization enhancement was examined. Fine linear relationships between the progress rate of atomization and standard deviation of velocity gradients were found. The fundamental mechanism of the atomization enhancement was discussed based on the obtained evaluation results.