Turbulent Spray Flames of Acetone and Ethanol Approaching Extinction

Masri, Assaad R.; Gounder, James D.

doi:10.1080/00102200903467754

Cited by 62 publications

(26 citation statements)

References 12 publications

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“…6 that the instantaneous conditional temperature images are mostly uniform in all flames shown here. This is consistent with the broad flame front observed in previous OH-LIF imaging (Masri and Gounder 2010) and implies that evaporation has little, if any, direct influence on the structure of the flame front. Neither the temperature images in Fig.…”

Section: Instantaneous Imagessupporting

confidence: 90%

Temperature imaging of turbulent dilute spray flames using two-line atomic fluorescence

et al. 2014

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This paper reports the first application of nonlinear excitation regime two-line atomic fluorescence imaging (NTLAF) of indium to measure temperature in turbulent flames of dilute sprays. Indium chloride is dissolved in acetone fuel which is atomised with an ultrasonic nebuliser and supplied with carrier air into a standard piloted burner. It is found that the indium fluorescence signal is not affected by scattering from the droplets or fuel vapour and that no changes to the optical arrangement used with gaseous flames were required. Notwithstanding the lower temperature thresholds of 800 K imposed by the population of excitation species for the NTLAF method and of 1,200 K imposed by the mechanism of releasing gas-phase indium from its salt, the comparisons of conditional and pseudo-unconditional means with thermocouple measurements performed in a range of turbulent spray flames are quite favourable. The NTLAF signal quality deteriorates on the jet centreline at upstream locations and on the lean side of the flame, the former being largely due to insufficient conversion of indium chloride to indium atoms and the latter potentially due to indium oxidation. Nevertheless, the signal-to-noise ratios obtained in the reaction zone regions are good and the results reveal the expected temperature trends in the turbulent spray flames tested here. Further developments are necessary to resolve the mechanism of indium formation and to broaden the temperature range.

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Section: Instantaneous Imagessupporting

confidence: 90%

Temperature imaging of turbulent dilute spray flames using two-line atomic fluorescence

et al. 2014

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“…Examples include gas turbine engines where fuel injection occurs slightly upstream of the combustor's exit plane such that the fuel issues partially premixed with the swirling air stream [1,2]; gasoline direct injection engines where various strategies are employed to control mixture stratification in ways that promote topology. Even in simple laboratory-scale geometries, lifted gaseous flames [10] and spray flames [11,12] are known to exhibit both premixed and diffusion modes in different parts of the overall flame.…”

Section: Introductionmentioning

confidence: 99%

Local extinction and near-field structure in piloted turbulent CH4/air jet flames with inhomogeneous inlets

Barlow

Meares

Magnotti

et al. 2015

Combustion and Flame

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a b s t r a c tLine-imaged measurements of temperature and major species, based on well-established Raman/Rayleigh/CO-LIF techniques, are used to better understand the scalar structure of piloted CH 4 /air jet flames with inhomogeneous inlets. Recent studies using a variant of the Sydney piloted burner have demonstrated that the blowoff velocity of a partially-premixed jet flame of CNG or CH 4 and air can be increased significantly by tailoring the mixture fraction profile at the burner exit. This is done by adding a small, retractable central tube within the main tube of the burner and separately supplying fuel and air for partial premixing. Both tubes are located within the pilot annulus. When the central tube is retracted far upstream of the burner exit, the flame has the same stability as that of the original burner with homogeneous fuel-air composition at the jet exit. However, when the inner tube supplies fuel and is retracted an optimal distance (10-13 times the main tube diameter) the blowoff velocity is increased by nearly 40%. Previous results indicated that combustion very close to the burner exit occurs in a stratified-premixed mode, augmenting the stabilizing effect of the pilot. This is followed by transition to a diffusion-dominated mode of burning within the first ten main tube diameters.The present paper provides a detailed examination of a series of piloted CH 4 /air jet flames with different inlet conditions and with a pilot flame that matches the composition and adiabatic flame temperature of CH 4 /air. It addresses trends in local extinction as well as differences in near-field flame structure. The evolution in the local mode of combustion is traced using instantaneous line-imaged realizations where the change in mixture fraction across a 1000 K interval is used as a conditioning variable. Doubly conditioned means of selected species mass fractions confirm that the flames with inhomogeneous inlet profiles undergo transition from a stratified-premixed mode of combustion to a diffusion-dominated mode of combustion within the first ten jet diameters. Calculations of strained laminar partially-premixed flames are used to gain insight on the effects of strain rate and fuel-side equivalence ratio on flame structure and the rate of heat release. These turbulent jet flames may serve as interesting test cases for models aimed at predicting the performance of practical burners that operate with mixed combustion modes.

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“…Few experimental studies focused on ethanol turbulent round spray flames. Marley et al [15] and Gounder et al [11] investigated the flame structure, Masri and Gounder [16] studied the ethanol and acetone spray flames' behavior in various regimes of instability, and O'Loughlin and Masri [17] analyzed auto-ignition of ethanol and acetone spray flames. There are even fewer numerical studies of ethanol turbulent spray flames.…”

Section: List Of Symbolsmentioning

confidence: 99%

Numerical simulation of an ethanol turbulent spray flame with RANS and diffusion combustion model

Filho

Fukumasu

Krieger

2013

J Braz. Soc. Mech. Sci. Eng.

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A detailed numerical simulation of ethanol turbulent spray combustion on a rounded jet flame is presented in this article. The focus is to propose a robust mathematical model with relatively low complexity submodels to reproduce the main characteristics of the coupling between both phases, such as the turbulence modulation, turbulent droplets dissipation, and evaporative cooling effect. A RANS turbulent model is implemented. Special features of the model include an Eulerian-Lagrangian procedure under a fully two-way coupling and a modified flame sheet model with a joint mixture fractionenthalpy b-PDF. Reasonable agreement between measured and computed mean profiles of temperature of the gas phase and droplet size distributions is achieved. Deviations found between measured and predicted mean velocity profiles are attributed to the turbulent combustion modeling adopted.

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Turbulent Spray Flames of Acetone and Ethanol Approaching Extinction

Cited by 62 publications

References 12 publications

Temperature imaging of turbulent dilute spray flames using two-line atomic fluorescence

Temperature imaging of turbulent dilute spray flames using two-line atomic fluorescence

Local extinction and near-field structure in piloted turbulent CH4/air jet flames with inhomogeneous inlets

Numerical simulation of an ethanol turbulent spray flame with RANS and diffusion combustion model

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