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Atomization and Sprays

Journal of the International Institutes for Liquid Atomization and Spray Systems

ISSN for PRINT: 1045-5110

Institutional price:	$787.00
Issues per year:	8

Best Paper Award Selection - Editorial Board Site

2004, Volume14

99 pages

Issue price - $85.00

THE FRACTAL GEOMETRY OF ROUND TURBULENT CRYOGENIC NITROGEN JETS AT SUBCRITICAL AND SUPERCRITICAL PRESSURES

B. Chehroudi
Engineering Research Corporation, P.O. Box 1718, Lancaster, California, USA

Douglas Talley
AFRL/PRSA Propulsion Directorate, Air Force Research Laboratory, Edwards Air Force Base, California, USA

ABSTRACT

Box-counting and Euclidean distance mapping (EDM) methods were used to measure the fractal dimension of round turbulent cryogenic nitrogen jets at pressures ranging from subcritical to supercritical pressures. Both methods produced similar trends, with close quantitative agreement for a suitably small box-counting scale. At subcritical pressures, the fractal dimension was found to be consistent with the fractal dimension of a spray in the second wind-induced atomization regime. The fractal dimension tended to increase as pressure increased, until at supercritical pressures the fractal dimension was found to be consistent with that of gas jets and mixing layers. The results constitute additional quantitative evidence for the hypothesis that subcritical jets exhibit mainly spraylike behavior, while supercritical jets exhibit mainly gaslike behavior. This appears to have been the first time pressure effects on the fractal dimension of turbulent jets have been measured.