Near-threshold soot formation in premixed flames at elevated pressure

Mi, Xiaotong; Saylam, Ahmad; Endres, Torsten; Schulz, Christof; Dreier, Thomas

doi:10.1016/j.carbon.2021.05.014

Cited by 11 publications

(9 citation statements)

References 65 publications

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“…Studies such that of Gu et al [21] and of Liu et al [40] realise that the pressure increasing enhances all the soot formation processes (precursors forming, nucleation, coalescence and agglomeration processes) and thus the final soot volume fraction (fV) showed an approximate power-law relation with pressure. The pressure exponent for laminar premixed ethylene/air flame is found to be in the range of 1.4-2 depending to pressure and to HAB [6,7,22,23]. At this point, it is important to note that Heidermann et al [7] attributed the appearance of luminous soot streaks in high-pressure sootingflames to the non-planarity and inhomogeneity of the burner matrix.…”

Section: Introductionmentioning

confidence: 95%

“…To study the effect of pressure on soot formation several enclosed burner designs were employed [1][2][3][4][5][6][7]. Generally, these burners are often equipped with multi-optical ports allowing flame investigation using various optical diagnostic techniques.…”

Section: Introductionmentioning

confidence: 99%

“…The more common one is by shielding the target sooting-flame by an inert-gas coflow at relatively high velocity near to those of the hot burned gases [15]. The second one, which is more efficient to limit the heat transfer with the surrounding, is the protection of the target sooting-flame by another well selected co-annular flame, which is often a slightly fuel-rich non-sooting methane/air flame [1][2][3][4][5][6]. Therefore, the inner matrix of target sooting-flame is surrounded by a co-annular one to envelop the shielding coflow of an inert gas or other premixed non-sooting flame mixture.…”

Section: Introductionmentioning

confidence: 99%

“…As the aim of this work is to investigate the second order effect of burner optical ports and EIM and the first one of pressure on the soot formation evaluation and premixed sooting-flame behaviour, especially that of the appearance of luminous soot streaks in high-pressure sooting-flames, we first investigate by 3D-simulations the ability to justify 2D-and/or 1D-simulations to predict the centerline profiles of gas temperature, species and soot concentration and particle size for the investigation of laminar premixed sooting-flames in an enclosed high-pressure burner. 2D-and 1D-simulation predictions of ethylene/air sooting-flames data conducted using the same enclosed burner by Mi et al [6] are then performed as a demonstration study. Afterword, the justified 2D-simulation approach is implemented to investigate the target effects of EIM and pressure on sootingflame evaluation and behaviour.…”

Section: Introductionmentioning

confidence: 99%

“…Afterword, the justified 2D-simulation approach is implemented to investigate the target effects of EIM and pressure on sootingflame evaluation and behaviour. The highest pressure, 10 bar, experimentally investigated by Mi et al [6] is chosen for the high-pressure study in order to obtain a distinct effect of pressure on the sooting-flame compared to atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%

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Behaviour of Premixed Sooting-Flame in A High-Pressure Burner

Saylam¹

2023

Preprint

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The second-order factor effect of burner optical ports and Edge inter-matrices (EIM) and the first one of pressure on soot formation process and behaviour of premixed sooting-flame in a high-pressure burner are numerically investigated here. Three-dimensional CFD simulations of a premixed flame C2H4/air at p = 1.01 and 10 bar using one-step chemistry approach are first performed to justify satisfied predictability of prospective axisymmetric bi-dimensional (2D) and one- dimensional (1D) simulations. The justified 2D-simulation approach shows the generation of an axial vorticity around the EIM and axial multi-vorticities due to the high expansion rate of burnt gases at the high-pressure of 10 bar. This leads to the development of axial multi-sooting zones, which are manifested experimentally by visible luminous soot streaks, and to boosting soot formation conditions of relatively low-temperature field, < 1800 K, and high-mixing rate of gases in combustion around and above the EIM location. Nevertheless, tolerable effect on the axial soot volume fraction (fV) profile, fV < 3%, is manifested only at high heights above burner of the atmospheric sooting-flame C2H4/air phi = 2.1 and early at the high-pressure 10 bar of this flame, fV < 10%. Enhancing the combustion process reactivity by decreasing the rich equivalence ratio of fuel/air mixture and/or rising the pressure results prior formation of soot precursors which shifts the sooting zone upstream.

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Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Behaviour of Premixed Sooting-Flame in A High-Pressure Burner

Saylam¹

2023

Preprint

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Simultaneous application of soot and temperature measurements in a pressurized turbulent flame by laser-induced incandescence and coherent anti-Stokes Raman scattering for particle sizing

Geigle¹,

Scheffold²,

Nau³

et al. 2023

Appl. Phys. B

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Simultaneous application of multi-channel laser-induced incandescence (LII) and shifted vibrational coherent anti-Stokes Raman scattering (SV-CARS) to study sooting flames is demonstrated for the first time. The potential of this diagnostics combination is evaluated on the basis of characterization of soot particles and correlation of soot presence with temperature. For that purpose, a sooting swirl flame operated at three bars has been employed with ethylene as fuel. The novel combination of CARS and time-resolved LII (TiRe LII) enables the estimation of particle size and correlation of this quantity with local gas temperature; simultaneously acquired 2D LII images provide information on the soot distribution in the ambience of the measurement volume which is used by CARS and TiRe LII. Even if the used LII model is approximative in some respect, the detected LII decay times indicate very small particle size throughout the flame relative to an atmospheric laminar diffusion flame which was used for comparison. In most instances, soot presence relates to local gas temperatures in a range between 1600 and 2400 K. Rare soot events at cooler temperatures occur near the nozzle exit and are attributed to transported soot. Comparison of the peak soot temperatures during the LII process shows a significant decrease in the turbulent pressurized flame relative to the laminar atmospheric reference flame. This is attributed to a less-efficient LII heat-up process at turbulent pressurized conditions due to beam steering. The background blackbody temperature, which can be derived by evaluating the signal captured in the different color channels of the LII system towards the end of the LII process, has been identified to be mostly controlled by hotter soot filaments between the laser plane and the detector. Thus, the LII signal tail is not a good measure of the local gas temperature in the measurement volume for this type of configuration.

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