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Atomization and Sprays
IF: 1.189 5-Year IF: 1.596 SJR: 0.814 SNIP: 1.18 CiteScore™: 1.6

ISSN Print: 1044-5110
ISSN Online: 1936-2684

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Atomization and Sprays

DOI: 10.1615/AtomizSpr.2018020984
pages 1-21

DYNAMICS OF NEAR-FIELD AND FAR-FIELD SPRAY FORMED BY LIQUID JET IN OSCILLATING CROSSFLOW

A. Sharma
Department of Aerospace Engineering and Engineering Mechanics University of Cincinnati, Cincinnati, Ohio 45221-0070, USA
Jong Guen Lee
Department of Aerospace Engineering and Engineering Mechanics University of Cincinnati, Cincinnati, Ohio 45221-0070, USA

ABSTRACT

The effect of crossflow oscillations on the near-field and the far-field spray is studied. Experiments are conducted over a range of Weber numbers ranging from 18 to 250, covering various breakup regimes. The crossflow is modulated in the frequency range of 90−450 Hz, with modulation level varying between 5% and 20% of mean crossflow velocity. The response of the near-field spray is quantified in terms of the ratio of the observed fluctuation of momentum flux ratio extracted from a correlation of upper penetration to the expected fluctuation of momentum flux ratio corresponding to the oscillating crossflow velocity. The strength of the response is found to be mainly dependent on the crossflow oscillation frequency, with the strength of response decreasing with increase in frequency. The mean momentum flux ratio and the modulation level of crossflow are found to have relatively negligible effects on the level of normalized spray response. In the far field, the spray is found to respond to crossflow oscillations by exhibiting an "up-and-down flapping" behavior at low crossflow modulation frequency and its mode switches to the "on-and-off mode" as the crossflow modulation frequency increases. The spray width and height also fluctuate in the presence of crossflow oscillation: the amplitude of spray height fluctuation is greater for low frequency and becomes less with an increase in frequency. A comparison of the near-field and far-field response suggests that the initial response of the liquid jet fades away as the spray convects downstream, and the far-field spray response is weakened a lot more quickly as the modulation frequency increases.