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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)

FRACTAL ANALYSIS OF IGNITED DIESEL SPRAY STRUCTURES

Raffaele Ragucci
Istituto di Ricerche sulla Combustione, CNR, P.le Tecchio 80, 80125 Naples, Italy

Antonio Cavaliere
Dipartimento di Ingegneria Chimica, Università di Napoli "Federico II", Naples, Italy

C. Noviello
D.I.M.E.(Dipartimento di Ingegneria Meccanica per l’Energetica), Universitá Federico II, Naples, Italy

A. Rizzo
Dip Ingegneria Chimica, Universita Federico II, Napoli, Italy

G. Vanacore
Dip Ingegneria Meccanica, Universita Federico II, Napoli, Italy

Abstract

Counting box techniques, used in the fractal analysis of turbulent field are used for the study of the spatial distribution of soot clouds produced during the combustion of a diesel spray. The main counting box techniques, available for this analysis, are introduced and their physical implications are discussed.
Even though the experimental images obtained from the laser light scattering imaging technique are not "true" fractals, the investigation tools, provided from the fractal analysis of two-dimensional patterns, can give a synthetic description of the spatial distribution of the soot clouds.
A main characteristic length of the soot cloud in the order of 1 mm identified and a nearly uniform scattering intensity distribution inside the clouds is revealed. These results suggest that the fuel droplets or fragment produced in the diesel spray, presented in this paper, are not well dispersed and, as a consequence, the droplets inside a cloud vaporize and pyrolyze all together in the same time originating nearly uniform concentrations of carbonaceous particulates.
The purpose of the paper was not only to give information on the diesel combustion process, but also to introduce the counting box techniques as new pattern recognition tools that can be used in the analysis of any random process linked to isothermal and burning sprays.