Burning times of linear fuel droplet arrays: A comparison of experiment and theory

Sangiovanni, J.J.; Labowsky, M.

doi:10.1016/0010-2180(82)90086-4

Cited by 77 publications

(25 citation statements)

References 11 publications

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“…Since the single/multiple droplets combustion is considered as a basic unit of the spray combustion, a number of articles have been published so far on this subject [ex. [1][2][3][4][5][6][7][8][9][10]. Theoretical works of the single droplet combustion have been progressed by taking advantage of its symmetric nature.…”

Section: Impact Of Microgravity Environment For Studies On Droplet Comentioning

confidence: 99%

“…Early theoretical works on the interaction have been found in 60's, successfully showing that the flame-flame interaction could modify not only the flame shape but also the combustion characteristics (e.g., life time of droplets) [5][6][7]. To validate these theories, a series of corresponding experiment of single/multiple droplet(s) combustion have been performed, but the most of successful ones were done after 80's [8][9][10]; nearly two-decades later. The reason for this "long delay" is because a difficulty of performing experiment under an ideal condition which the most of theories need to assume; namely, the flame must be perfectly spherical without any disturbance.…”

Section: Impact Of Microgravity Environment For Studies On Droplet Comentioning

confidence: 99%

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Development of "Tiny" Droplet Flame Simulator: "Super-Stabilized" Micro-Jet Flame in a Hot Air

Fujiwara

Nakamura

Hirasawa

2011

JTST

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An attempt to form a "tiny" spherical flame over the small jet burner (so called microflame) as a model of a tiny droplet flame was made experimentally without any assistance brought by large facilities which could eliminate/minimize buoyancy effect. Using ceramic burner and high-temperature air effectively suppresses the quenching distance and such "super-stabilized" micro-jet flame would be fairly close to 1-D (droplet) flame. The temperature of air (up to 770 K) and the fuel (methane) flow rate were varied as experimental parameters. Fundamental characteristics of limiting and near-extinction behavior of methane-air microflame in high-temperature air are investigated. Results show that the flame shape under high-temperature air condition is hardly affected by the external disturbance and the quenching distance is minimized due to the increase of the temperature at burner tip. It is found that the theory developed by Kuwana et al., to predict the limiting behavior of small-scale flame would be applicable even for the one formed in high-temperature air. Minimum flame size achieved in high-temperature air is predicted as an order of hundreds micron; interestingly, this is identical to what is predicted with ideal adiabatic burner (i.e., no conductive and radiative heat loss to/from the burner) in our previous numerical work.

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Section: Impact Of Microgravity Environment For Studies On Droplet Comentioning

confidence: 99%

Section: Impact Of Microgravity Environment For Studies On Droplet Comentioning

confidence: 99%

Development of "Tiny" Droplet Flame Simulator: "Super-Stabilized" Micro-Jet Flame in a Hot Air

Fujiwara

Nakamura

Hirasawa

2011

JTST

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“…Even for arrays in convective conditions, this parameter has been used as a measure of droplet to droplet interaction [14,15]. Characteristic limiting values of ᐉ for interaction to occur have been measured approximately to 20 to 30 droplet diameters [15]. However, droplet clouds are considered to be more effective in preventing single droplet burning, with values of interdroplet distance reaching 50 diameters in laminar sprays of monodisperse droplets [3].…”

Section: S Russo and A Gomezmentioning

confidence: 99%

Section: S Russo and A Gomezmentioning

confidence: 99%

“…They ignited as they emerged from the flame, burned and subsequently extinguished. The array configuration provided a convenient and well-controlled way to carry out these interaction experiments and was widely used in the past to study flame structure [10] [11] [12], fluid dynamics interactions [13], ignition properties [14], and droplet burning time [15]. In the present study we identify the controlling parameter for the onset of interactive effects on the droplet extinction phenomenon and analyze the effect of the oxidizer mass fraction on the extinction of alcohol droplets.…”

Section: Introductionmentioning

confidence: 99%

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The extinction behavior of small interacting droplets in cross-flow

Russo¹,

Gomez²

2002

Combustion and Flame

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Experiments were conducted on monodisperse streams of small (Ͻ100 m) methanol and ethanol droplets, injected perpendicularly to the axis of an axisymmetric methane diffusion flame. After crossing the methane flame, the droplets ignited and continued to burn outside of the "domain of influence" of the gaseous flame till they eventually extinguished. The extinction behavior was studied as a function of droplet spacing, oxidizer concentration and velocity, and droplet velocity by measuring droplet size and velocity at the time of extinction using a commercial Phase Doppler Anemometer. The onset of droplet interaction effects on extinction was found at interdroplet distances well above the limits reported in the literature. The interaction is attributed to the vitiated atmosphere left behind by the leading droplet that affects the extinction conditions of the trailing one. The ratio between interdroplet time and convection time normal to the droplet direction of travel was found to be the controlling parameter. Results were correlated in terms of a critical Damköhler number that was found to scale as dY o,ϱ no /v, where d is the droplet diameter, Y o,ϱ is the oxidizer mass fraction, v is the droplet velocity, and n o is 0.5 and 0.75 for methanol and ethanol, respectively.

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Disruptive burning of precursor/solvent droplets in flame‐spray synthesis of nanoparticles

et al. 2013

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Flame spray pyrolysis is an established technique for synthesizing nanoparticles in the gas phase through aerosol combustion of precursor/solvent droplets. The combustion characteristics of isolated micron-sized precursor/solvent droplets are investigated experimentally. Pure solvent droplets burn uniformly and classically quasisteady, whereas precursor/ solvent droplets manifest disruptive combustion behavior. The fast onset of droplet disruption, which occurs only for solutions with dissolved metal precursors, is not due to solid-particle precipitation within the droplet. Instead, the mechanism of disruptive droplet burning is similar to that of slurry droplets, consisting of three main steps: (1) diffusioncontrolled burning of the high-volatile solvent, (2) viscous-shell formation due to decomposition of the low-volatile metal precursor, and (3) subsequent disruption due to heterogeneous nucleation. The time sequence of the three steps depends on the concentration and decomposition characteristics of the metal precursor, shortening with increased concentration and higher incremental decomposition temperature.

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Burning times of linear fuel droplet arrays: A comparison of experiment and theory

Cited by 77 publications

References 11 publications

Development of "Tiny" Droplet Flame Simulator: "Super-Stabilized" Micro-Jet Flame in a Hot Air

Development of "Tiny" Droplet Flame Simulator: "Super-Stabilized" Micro-Jet Flame in a Hot Air

The extinction behavior of small interacting droplets in cross-flow

Disruptive burning of precursor/solvent droplets in flame‐spray synthesis of nanoparticles

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