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Secondary atomization in the combustion of electrostatic spraysThe combustion of electrosprays in a laminar counterflow diffusion flame has been experimentally studied by measuring droplet size and velocity distributions and gas-phase temperature. Detailed examination of the evolution of droplet size distribution as droplets approach the flame shows that, if substantial evaporation occurs before droplets 'interact' with the flame, the size distribution becomes bimodal. A secondary, sharp peak, in fact, develops in correspondence of diameters about one order of magnitude smaller than the mean. No evaporation mechanism can account for the development of such bimodality, that can be explained only in terms of a disintegration of droplets into finer fragments of size much smaller than the parent ones. This fission is of electric nature and it occurs when the repulsion of electric charges overcomes the surface tension cohesive force ultimately leading to a disintegration into finer fragments at or about the so-called Rayleigh limit. We here report on the first observation in combustion environments of such 'explosions'. If, on the other hand, droplets enter the very high temperature region before exploding, there appears to be no evidence of bimodality in their size distribution. In this case, in fact, flame chemi-ions may neutralize the charge on the droplets and thus prevent disruption.
Document ID
19930066113
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Gomez, Alessandro
(NASA Lewis Research Center Cleveland, OH, United States)
Chen, Gung
(Yale Univ. New Haven, CT, United States)
Date Acquired
August 16, 2013
Publication Date
June 1, 1993
Subject Category
Inorganic And Physical Chemistry
Report/Patent Number
AIAA PAPER 93-2332
Meeting Information
Meeting: AIAA, SAE, ASME, and ASEE, Joint Propulsion Conference and Exhibit
Location: Monterey, CA
Country: United States
Start Date: June 28, 1993
End Date: June 30, 1993
Sponsors: ASEE, ASME, AIAA, SAE
Accession Number
93A50110
Funding Number(s)
CONTRACT_GRANT: NAG3-1259
Distribution Limits
Public
Copyright
Other

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