Imaging of premixed flames in microgravity

Kostiuk, Larry W.; Cheng, R.K.

doi:10.1007/bf00209361

Cited by 25 publications

(8 citation statements)

References 7 publications

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“…Power spectral analysis based on the data collected with the PM and the microphones show that the main peak in both cases corresponds to the oscillation frequency f = 16 ± 1 Hz. These measurements are in agreement with the flickering frequency deduced from the correlation of(Kostiuk and Cheng 1994):…”

supporting

confidence: 88%

“…where the superscripts(•) and (•) ′ are used to represent the mean and fluctuating componentsrespectively. This may not be the case in some practical configurations, but it is admitted here.For laminar flames stabilized on the rim of a burner, buoyancy effects induce a low frequency oscillation of the hot plume without significant change of temperature and composition of the burned gases before the flame tip(Kostiuk and Cheng 1994;Durox et al 1997b). This results in turn in small perturbations in heat release rate and fluctuations of the burned gases volume.…”

mentioning

confidence: 99%

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Determination of Heat Release Rate Disturbances in Unconfined Flames Based on Fluctuations in the Travel Time of Ultrasonic Waves

Li¹,

Richecoeur²,

Schuller³

2012

Combustion Science and Technology

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supporting

confidence: 88%

mentioning

confidence: 99%

Determination of Heat Release Rate Disturbances in Unconfined Flames Based on Fluctuations in the Travel Time of Ultrasonic Waves

Li¹,

Richecoeur²,

Schuller³

2012

Combustion Science and Technology

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“…It is found that the flame flickering under normal gravity originates primarily due to Kelvin-Helmholtz type instability in the buoyancy induced shear layer surrounding the flame surface [4]. The flickering frequency is observed to remain between 10 and 20 Hz in premixed flames [5,6] due to the instability at the interface be-* Corresponding author.…”

Section: Introductionmentioning

confidence: 97%

Effects of fuel type and equivalence ratios on the flickering of triple flames

Sahu

Kundu

Ganguly

et al. 2009

Combustion and Flame

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“…This compact module (0.9m x 0.9m x 0.45m) was originally fitted with laser schlieren for drop tower experiments [9]. In conversion to LDV, a 2 axes computer controlled translation stage had been added to move the burner relative to the fixed LDV probe.…”

Section: µG Experimental Setup and Ldv Systemmentioning

confidence: 99%

Effects of buoyancy on lean premixed v-flames, Part II. VelocityStatistics in Normal and Microgravity

Cheng¹,

Bédat²,

Yegian³

1999

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The field effects of buoyancy on laminar and turbulent premixed v-flames have been studied by the use of laser Doppler velocimetry to measure the velocity statistics in +1g, -1g and µg flames. The experimental conditions covered mean velocity, U o , of 0.4 to 2 m/s, methane/air equivalence ratio, φ, of 0.62 to 0.75. The Reynolds numbers, from 625 to 3130 and the Richardson number from 0.05 to 1.34. The results show that a change from favorable (+1g) to unfavorable (-1g) mean pressure gradient in the plume create stagnating flows in the farfield whose influences on the mean and fluctuating velocities persist in the nearfield even at the highest Re we have investigated. The use of Richardson number < 0.1 as a criterion for momentum dominance is not sufficient to prescribe an upper limit for these buoyancy effects. In µg, the flows within the plumes are non-accelering and parallel. Therefore, velocity gradients and hence mean strain rates in the plumes of laboratory flames are direct consequences of buoyancy. Furthermore, the rms fluctuations in the plumes of µg flames are lower and more isotropic than in the laboratory flames to show that the unstable plumes in laboratory flames also induce velocity fluctuations. The phenomena influenced by buoyancy i.e. degree of flame wrinkling, flow acceleration, flow distribution, and turbulence production, can be subtle due to their close coupling with other flame flow interaction processes. But they cannot be ignored in fundamental studies or else the conclusions and insights would be ambiguous and not very meaningful.

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Imaging of premixed flames in microgravity

Cited by 25 publications

References 7 publications

Determination of Heat Release Rate Disturbances in Unconfined Flames Based on Fluctuations in the Travel Time of Ultrasonic Waves

Determination of Heat Release Rate Disturbances in Unconfined Flames Based on Fluctuations in the Travel Time of Ultrasonic Waves

Effects of fuel type and equivalence ratios on the flickering of triple flames

Effects of buoyancy on lean premixed v-flames, Part II. VelocityStatistics in Normal and Microgravity

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