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Quasi-steady flame standoff ratios during methanol droplet combustion in microgravity

Published on Jan 1, 2010in Combustion and Flame4.12
· DOI :10.1016/j.combustflame.2009.09.012
Vedha Nayagam13
Estimated H-index: 13
(Glenn Research Center)
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Abstract
Abstract Recently, Aharon and Shaw developed a simplified analytical expression to predict quasi-steady flame stand-off ratios for alkane fuels. Their analysis is strictly valid only for alkane-type fuels where there is no reabsorption of flame generated species back into the droplet. In this note we show that Aharon and Shaw’s analysis can be extended to methanol droplet combustion where water generated at the flame-sheet is absorbed back into the droplet. The model predictions are shown to compare well with available experimental results.
  • References (5)
  • Citations (4)
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References5
Newest
Published on Jan 1, 1999in Combustion and Flame4.12
Fernando Fachini Filho2
Estimated H-index: 2
(INPE: National Institute for Space Research)
A process for producing a printed wiring board, particularly an interposer for a chip size package, which comprises the steps of (1) forming an outer insulator layer 22 having outer via-holes 24 on a substrate 32, (2) forming conducting passages 31 through the outer via-holes 24 by plating with metal up to substantially the same level as the upper surface of the outer insulator layer 22, (3) forming a thin metal film 29 on the outer insulator layer 22 and on the conducting passages 31, (4) formi...
Published on Apr 1, 1996in Combustion and Flame4.12
Anthony J. Marchese23
Estimated H-index: 23
(Princeton University),
Frederick L. Dryer66
Estimated H-index: 66
(Princeton University)
Abstract The time-dependent combustion of isolated, bicomponent liquid droplets of methanol and water is simulated using a spherosymmetric, finite-element, chemically reacting flow model. The computations consider multi-component molecular transport and detailed chemical kinetics (19 species, 89 forward reactions) in the gas phase; semiempirically formulated vapor-liquid equilibrium with water vaporization/condensation at the liquid surface; and liquid species mass transfer and energy conservati...
Published on Mar 1, 1991in Combustion Science and Technology1.56
Ishwar K. Puri35
Estimated H-index: 35
(UCSD: University of California, San Diego),
Paul A. Libby36
Estimated H-index: 36
(UCSD: University of California, San Diego)
Abstract The combustion of spherical droplets burning in a quiescent oxidizing atmosphere is considered. Chemical reactions are localized in a flame sheet at which the water-gas shift reaction is taken to be in equilibrium. Since nitrogen exists in relatively large concentrations throughout the flowfield, the diffusive properties of each species are described in terms of its binary coefficient with nitrogen. The chemistry model results in molecular hydrogen being present throughout the flow with...
Published on Jul 1, 1985in Acta Astronautica2.48
F.A. Williams2
Estimated H-index: 2
(Princeton University)
Abstract The spherically symmetrical combustion of a fuel droplet in an oxidizing atmosphere is considered. Theoretical results are given concerning the ignition, gas-phase unsteadiness, liquid-phase unsteadiness, quasisteady burning, disruptive burning and extinction phenomena encountered. Experimental methods for testing theoretical predictions are presented.
Published on Jan 1, 1977in Combustion and Flame4.12
Chung K. Law77
Estimated H-index: 77
(NU: Northwestern University),
H.K. Law1
Estimated H-index: 1
(NU: Northwestern University)
Abstract A previously formulated variable-property theory for a class of heat and mass transfer problems, exemplified by droplet vaporization and combustion, is generalized herein such that in addition to the previous features that the specific heats C , the thermal conductivity k , and the binary diffusion coefficient D ij are temperature dependent whereas C and k are further concentration-weighted, in the present formulation the D ij 's are also distinct for all species pairs. Explicit express...
Cited By4
Newest
Published on Sep 1, 2013in Combustion and Flame4.12
Inkant Awasthi2
Estimated H-index: 2
,
George Gogos17
Estimated H-index: 17
,
T. Sundararajan29
Estimated H-index: 29
(Indian Institute of Technology Madras)
Abstract Results are presented from numerical simulations of the combustion process of an isolated methanol droplet in a nearly quiescent ambient air ( T ∞ = 1200 K, and p ∞ = 1 atm.). The focus is on the effects of size variation for droplets which are present in a practical spray. We show a gradual transition from a kinetically controlled regime of small droplets to a diffusion controlled regime of large droplets. The analysis underlines the importance of accurate chemical kinetics, especially...
Published on Oct 9, 2012
Vedha Nayagam13
Estimated H-index: 13
,
Daniel L. Dietrich13
Estimated H-index: 13
+ 2 AuthorsForman A. Williams48
Estimated H-index: 48
Motivated by the need to understand the flammability limits of condensed-phase fuels in microgravity, isolated single droplet combustion experiments were carried out in the Combustion Integrated Rack facility onboard the International Space Station. Experimental observations of methanol droplet combustion and extinction in oxygen/carbon-dioxide/nitrogen mixtures at 0.7 and 1 atmospheric pressure in quiescent microgravity environment are reported for initial droplet diameters varying between 2 mm...
Published on Jan 1, 2012in Combustion and Flame4.12
Tanvir Farouk17
Estimated H-index: 17
(Princeton University),
Frederick L. Dryer66
Estimated H-index: 66
(Princeton University)
Abstract Tethered methanol droplet combustion in carbon dioxide enriched environment is simulated using a transient one-dimensional spherosymmetric droplet combustion model that includes the effects of tethering. A priori numerical predictions are compared against recent experimental data. The numerical predictions compare favorably with the experimental results and show significant effects of tethering on the experimental observations. The presence of a relatively large quartz fiber tether incr...
Published on Oct 1, 2011in Combustion Science and Technology1.56
Benjamin D. Shaw13
Estimated H-index: 13
(UC Davis: University of California, Davis),
J. B. Wei4
Estimated H-index: 4
(UC Davis: University of California, Davis)
Reduced gravity and normal gravity combustion experiments were performed with individual fiber-supported n-heptane and 1-propanol droplets with initial diameters in the 1-mm size range. Experiments were performed with air-inert mixtures at 0.1 MPa or 0.3 MPa and about 298 K, where helium, carbon dioxide, or xenon were separately used as inerts. The amount of inert gas required to suppress combustion was generally higher in reduced gravity than normal gravity, and higher mole fractions of xenon w...