An experimental study of effect of inert gases on extinction of laminar diffusion flames

Ishizuka, Satoru; Tsuji, Hiroshi

doi:10.1016/s0082-0784(81)80074-4

Cited by 93 publications

(60 citation statements)

References 9 publications

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“…39 Also, correlations of strain effects for turbulent flames 40 employ global strain rate estimates based on the coldgas conditions. Furthermore, most early experiments on strained flames, e.g., Ishizuka and Tsuji, 7 reported only global strain rates, and most theoretical works on edge-flames and instabilities of stretched flames 12,14,15,16 have used the constant-density assumption, thereby sidestepping the issue of flow-field modification near the flame edge due to thermal expansion.…”

Section: Insulationmentioning

confidence: 99%

“…It is well known theoretically and experimentally that both premixed flames 1,2,3,4,5,6 and nonpremixed flames 7,8,9 exhibit diffusive-thermal instability (DTI) that leads to cellular flame structures at low Lewis number (Le) of the stoichiometrically limiting reactant (fuel or oxidant). Here Le is defined as the ratio of the thermal diffusivity of the bulk mixture to the mass diffusivity of the reactant.…”

Section: Introductionmentioning

confidence: 99%

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Diffusive-thermal instability of counterflow flames at low Lewis number

Kaiser¹,

Liu²,

Ronney³

2000

38th Aerospace Sciences Meeting and Exhibit

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The effects of hydrodynamic strain on diffusivethermal instabilities at low Lewis number were studied experimentally using a counterflow slot-jet apparatus with H 2 -O 2 -N 2 mixtures. Three configurations were examined:single premixed, twin premixed and nonpremixed flames. For all three configurations a wide variety of nonplanar flame structures were observed. Two extinction limits, one at very high strain (corresponding to a residence time limitation) and one at low strain (corresponding to a heat loss extinction) were found.For premixed flames, nonplanar structures occurred for a wide range of mixtures. In many cases, near extinction the flame structures reduced to a single "flame tube" elongated in the direction of extensional strain. An examination of stoichiometry effects revealed a critical equivalence ratio for instability similar to that known to exist for flame balls. At low flow velocities a transition to flames attached to the jet exits in complicated ways was noted, and at high flow velocities transition to turbulent flow was noted. For nonpremixed flames, nonplanar flame structures were observed only for near-extinction conditions, but the resulting flame shapes were quite similar to those of premixed flames. These results are compared to recent theoretical predictions.

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Section: Insulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Diffusive-thermal instability of counterflow flames at low Lewis number

Kaiser¹,

Liu²,

Ronney³

2000

38th Aerospace Sciences Meeting and Exhibit

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“…The air-borne water droplets can extinguish flames with sufficiently high droplet concentration and small droplet size [5,6], and sufficient water fluxes realized on the burning surfaces can suppress the fires at their origin [7]. It is well known that an aerodynamically-stretched flame is easier to extinguish [8,9]. It has been shown that, as the shear exerted on the flames increases, the required water mist flux for flame extinction decreases [10].…”

Section: Introductionmentioning

confidence: 99%

Physical Scaling of Water Mist Suppression of Pool Fires in Enclosures

Yang¹

2011

Fire Safety Science - Proceedings of the 10th International Sym

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A series of fire suppression experiments was conducted in two geometrically similar enclosures of 1:3 ratio to evaluate whether the Froude-modeling-based scaling methodology could reasonably reproduce the pool fire development under water mist application in different scales. The parameters considered in the evaluation were: enclosure size, door opening size, water mist spray condition, fire size, fire location and fire-shielding condition. The two enclosures measured 1.22 × 1.22 × 1.22 m and 3.66 × 3.66 × 3.66 m. Two door opening sizes were tested for each enclosure: 0.30 × 0.61 m high and 0.61 × 0.61 m for the Scale-1 enclosure, and 0.91 × 1.83 m high and 1.83 × 1.83 m for the Scale-3 enclosure. Two heptane fire sizes were selected for each enclosure. The quasi-steady heat release rates of the two pool fires for the Scale-1 enclosure were 25 and 57 kW, and the corresponding heat release rates were 380 and 860 kW for the two pool fires used in the Scale-3 experiments. Besides matching the quasi-steady heat release rates according to the scaling requirement, the fire developments under free-burn were also carefully scaled. Two water mist nozzles were used to produce the water mist sprays in the Scale-1 and Scale-3 enclosures; these two nozzles were operated at the designated pressures of 13.8 bar and 41.4 bar, respectively. In each enclosure, nine ceiling-mounted nozzles were arranged in a 3 × 3 pattern with equal nozzle-to-nozzle and nozzle-to-wall spacing. The experiments showed that the fire development in terms of heat release rate could be reasonably reproduced during free-burn and water mist application in the Scale-1 and Scale-3 enclosures, as well as the oxygen concentration inside the enclosure.

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“…Researches on diffusion flames include (1) researches on counterflow diffusion flames that are subject only to stretching due to the velocity gradient Yamaoka, 1967, 1969;Otsuka and Niioka, 1973;Ishizuka and Tsuji, 1981;Smooke et al, 1986;Chelliah et al, 1990;Sung et al, 1995;Chen et al, 2007); (2) experimental and numerical research on convex flames subject to a microjet blown into the center of counterflow diffusion flames (Takagi et al, 1996;Yoshida and Takagi, 1998;Finke and Grunefeld, 2000); and (3) research on cylindrical diffusion flames that stretch in the axial direction by Wang et al (2007), Hu et al (2007Hu et al ( , 2009, and the authors (2010,2011).…”

Section: Introductionmentioning

confidence: 99%

Influences of stretch and curvature on the temperature of stretched cylindrical diffusion flames

Suenaga

Yanaoka

Momotori

2016

JTST

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The structure of a counterflow-type cylindrical diffusion flame was studied experimentally to determine the effect of stretch and curvature. The cylindrical flame used in this study had a concave curvature with respect to the fuel stream. The fuels used were propane and methane, diluted with nitrogen, argon or helium. Diluent gases were used to change the Lewis number, Lef, of the fuel. Our results indicated that (1) the fuel was preheated to a high temperature by the concentric inward heat flow from the flame because the flame shape is concave curvature with respect to the fuel flow; (2) at constant flame stretch, flame temperature increased with a decrease in flame radius when Lef > 1, but decreased when Lef < 1; and (3) at constant flame radius, flame temperature decreased with increased flame stretch rate when Lef > 1, but increased when Lef < 1.

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An experimental study of effect of inert gases on extinction of laminar diffusion flames

Cited by 93 publications

References 9 publications

Diffusive-thermal instability of counterflow flames at low Lewis number

Diffusive-thermal instability of counterflow flames at low Lewis number

Physical Scaling of Water Mist Suppression of Pool Fires in Enclosures

Influences of stretch and curvature on the temperature of stretched cylindrical diffusion flames

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