ICLASS 97
Proceedings of the Seventh International Conference on Liquid Atomization and Spray Systems

ISBN Print: 89-950039-2-8

An Experimental Study on Droplet Interactions

DOI: 10.1615/ICLASS-97.480
pages 393-400

Abstract

This paper describes a basic experiment on rectilinear monosized droplets stream allowing the improvement of the understanding of the physical processes (droplet-droplet interaction, droplet evaporation,...) occuring in dense sprays. The droplet stream is investigated at different locations downstream by optical measurements to get the droplet diameter, temperature and velocity with or without combustion. To study the droplet stream in low interaction an electrostatic droplet deflector has been developed to increase the droplet spacing. Ethanol was the simulation fluid used during these experiments. The droplet stream was investigated in cold conditions to study the influence of droplet spacing on the drag coefficient. The distance parameter is defined by the ratio of droplet spacing to droplet size. The results are compared to the correlations of Mulholland and Zhu. These correlations overestimate the drag coefficient for distance parameters lower than 20. We propose a new correlation to improve the prediction of the drag coefficient for a large range of spacing parameter 2 < C < 40. The droplet stream was ignited as it passes through an electrically heated coil. The experimental results are compared to the classical D2 law, which overestimates the droplet evaporation in strong interaction. The preliminary results concern a burning droplet stream with an initial droplet diameter Dg0 = 124 μm and velocity Vg0 = 8.3 ms-1 and C0 = 2. For a distance parameter C = 12, the results do not match the D2 law showing the usefulness of the droplet deflector.