A Theoretical and Experimental Investigation of the Ignition of Fuel Droplets

Sangiovanni, J.J.; Kesten, A. S.

doi:10.1080/00102207708946793

Cited by 61 publications

(19 citation statements)

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“…The slightly earlier onset of the flame at high momentum is attributed to the increased relative velocity between the ambience and the droplet, which results in faster attainment of a flammable mixture due to mixing. 33,34 Because pure oxygen constitutes the ambient atmosphere, such that the flame size is small, it is also expected that the instantaneous flame-to-droplet diameter ratio should attain a constant value, suggesting a CQS process. 24 However, Figure 5b shows that the ratio varies as combustion proceeds.…”

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confidence: 99%

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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confidence: 99%

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

et al. 2013

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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].…”

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%

“…Specifically, droplets present a large radial component and a very small axial component, whereas the opposite holds for the seed particles. The method to generate the monodisperse droplet stream used in the present investigation is similar to the one implemented by Sangiovanni and Kesten [14]. A homemade vibrating orifice atomizer [17] provides a collimated, monodisperse stream of methanol droplets.…”

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confidence: 99%

“…The rate at which droplets are injected into the flame is controlled by an electrostatic charging/deflection mechanism that periodically selects a droplet from the main stream. Differently from [14], the charging of the droplets is obtained by induction using a plate positioned at the jet break-up. The frequency at which droplets are extracted from the main stream varies from 50 to 500 Hz.…”

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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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Ignition characteristics of liquid hydrocarbon fuels as single droplets

Bergeron

Hallett

1989

Can J Chem Eng

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An investigation into the effects of fuel boiling point and chemical type on the autoignition of single droplets of a number of pure hydrocarbons is reported. Ignition delay times were measured using the suspended droplet technique, and a numerical model was developed to extract reaction rate constants for the fuels. The results show that both fuel boiling point and chemical kinetics are important contributors to the ignition delay.Une Ctude sur les effets du point d'ibullition et du type chimique du carburant sur l'allumage de gouttelettes individuelles de nombreux hydrocarbures, est presentke. Le dClai d'allumage fut mesurC pour des gouttelettes suspendues, et un modele mathCmatique fut dkveloppk pour dCterminer les cokfficients de rCaction pour chaque carburant. Les risultats dCmontrent que le point d'Cbullition ainsi que la cinktique chimique contribuent largement au dklai d'allumage.

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A Theoretical and Experimental Investigation of the Ignition of Fuel Droplets

Cited by 61 publications

References 11 publications

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

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

The extinction behavior of small interacting droplets in cross-flow

Ignition characteristics of liquid hydrocarbon fuels as single droplets

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