The effect of exit Reynolds number on soot volume fraction in turbulent non-premixed jet flames

Mahmoud, Saleh; Nathan, Graham J.; Alwahabi, Zeyad T.; Sun, Zhiwei; Medwell, Paul R.; Dally, Bassam B.

doi:10.1016/j.combustflame.2017.08.020

Cited by 33 publications

(44 citation statements)

References 31 publications

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“…However, ex situ diagnostics are extractive processes that perturb the flow, and the method of extraction can alter the physical and chemical properties of the soot particles so that they are no longer representative of combustion environments. Additionally, probes are most widely used with laminar flames, and while they can be used to measure size distributions in turbulent flames (Boyette et al 2017), they cannot measure the high levels of spatial and temporal intermittency of soot formation in turbulent flames identified in many studies (Wang et al 2019a, b;Lammel et al 2007;Geigle et al 2019;Stöhr et al 2019;Geigle et al 2011Geigle et al , 2013Geigle et al , 2017Bartos et al 2017;Qamar et al 2005Qamar et al , 2009Mahmoud et al 2017Mahmoud et al , 2018Köhler et al 2011;Narayanaswamy and Clemens 2013). These techniques can be used as an accompaniment to in situ laser diagnostics that are currently the main diagnostic techniques used to characterize sooting behavior in turbulent flames.…”

Section: Introductionmentioning

confidence: 99%

“…Turbulent flames exhibit spatial and temporal fluctuations not present in laminar flames, as well as shorter residence times that add a level of complexity to soot studies (Wang et al 2019a, b;Lammel et al 2007;Geigle et al 2011Geigle et al , 2013Geigle et al , 2017Geigle et al , 2019Stöhr et al 2019;Bartos et al 2017;Qamar et al 2005Qamar et al , 2009Mahmoud et al 2017Mahmoud et al , 2018Köhler et al 2011;Narayanaswamy and Clemens 2013). Qamar et al (2005) investigated soot volume fraction in simple jets (SJ), precessing jets (PJ), and bluff body flames (BB).…”

Section: Introductionmentioning

confidence: 99%

“…They then expanded their work to cover piloted turbulent jet non-premixed flames showing the intermittency of soot, and that turbulence reduces peak soot volume fractions compared to those in laminar flames (Qamar et al 2009). Mahmoud et al presented work on non-premixed turbulent jet flames that were operated at different exit strain rates (Mahmoud et al 2017(Mahmoud et al , 2018. Their work revealed that soot volume fraction is inversely proportional to exit strain rate, but that the location of maximum soot volume fraction is independent of strain rate (Mahmoud et al 2017(Mahmoud et al , 2018.…”

Section: Introductionmentioning

confidence: 99%

“…Mahmoud et al presented work on non-premixed turbulent jet flames that were operated at different exit strain rates (Mahmoud et al 2017(Mahmoud et al , 2018. Their work revealed that soot volume fraction is inversely proportional to exit strain rate, but that the location of maximum soot volume fraction is independent of strain rate (Mahmoud et al 2017(Mahmoud et al , 2018. Köhler et al (2011) investigated the interaction between turbulence and soot formation on a turbulent ethylene-air jet flame.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of Soot Production and Oxidation in a Lab-Scale Rich–Quench–Lean (RQL) Burner

Helou

Skiba

Mastorakos

2020

Flow Turbulence Combust

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Swirl-stabilized, turbulent, non-premixed ethylene-air flames at atmospheric pressure with downstream radially-injected dilution air were investigated from the perspective of soot emissions. The velocity and location of the dilution air jets were systematically varied while the global equivalence ratio was kept constant at 0.3. The employed laser diagnostics included 5 kHz planar laser-induced fluorescence (PLIF) of OH, 10 Hz PAH-PLIF, and 10 Hz laser-induced incandescence (LII) imaging of soot particles. OH-PLIF images showed that the reaction zone widens with dilution, and that regions with high OH-LIF signal shift from the shear layer to the axis of the burner as dilution increases. Dilution is effective at mitigating soot formation within the central recirculation zone (CRZ), as evident by the smaller PAH-containing regions and the much weaker LII signal. Dilution is also effective at halting PAH and soot propagation downstream of the dilution air injection point. The high momentum dilution air circulates upstream to the root of the flame and reduces fuel penetration lengths, induces fast mixing, and increases velocities within the CRZ. Soot intermittency increased with high dilution velocities and dilution jet distances up to two bluff body diameters from the burner inlet, with detection probabilities of < 5% compared to 50% without dilution. These results reveal that soot formation and oxidation within the RQL are dependant on the amount and location of dilution air injected. This data can be used to validate turbulent combustion models for soot.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental Investigation of Soot Production and Oxidation in a Lab-Scale Rich–Quench–Lean (RQL) Burner

Helou

Skiba

Mastorakos

2020

Flow Turbulence Combust

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“…The shear-type instabilities bring variation in the rate of aerodynamic stress on the exit flow from the burner, and is defined in terms of strain rate (Du et al 1989). The strain rate at the exit of the nozzle influences soot formation processes and has been studied substantially by many researchers as discussed in the work done by Mahmoud et al (2018), Qamar et al (2005Qamar et al ( , 2009 Kent and Bastin (1984) In a relatively more recent study, Qamar (2009) performed a detailed simulation of the distribution of SVF from a piloted turbulent jet non-premixed flame (Delft Flame 3).…”

Section: Flow Regimes Of Turbulent Non-premixed Flamesmentioning

confidence: 99%

Application of an Optical Diagnostic (LII/ELS) to Measure Soot Formation Trends within Turbulent Buoyant Non-Premixed Flames

Sethi¹

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Flaring in the upstream oil and gas industry generates black carbon, which adversely affects human health and is an important positive climate forcer. Experiments were performed to investigate soot formation and oxidation within these large, flare-type, turbulent, nonpremixed, buoyant flames. An optical measurement technique combining simultaneous auto-compensating Laser-Induced Incandescence (LII) and Elastic Light Scattering (ELS) measurements was used to measure the instantaneous soot volume fraction (fv), primary particle diameter (dp), and mean aggregate radius of gyration (Rgm1) of soot black carbon within an optical probe volume. Measurements were completed on two comparable turbulent buoyant flames emanating from a 50.8 mm diameter pipe (lab-scale flare) with and without an internal turbulence generating grid. Centreline profiles of fv, dp, and Rgm1 were determined within rigorously quantified uncertainties obtained via Monte Carlo analysis. Results show that, for the conditions investigated, internal pipe turbulence has only a minor effect on the soot formation trends within the flame, suggesting that internal turbulence is likely less important than other factors when modelling and predicting soot formation in flare flames. iii Acknowledgements Foremost, I would like to thank my supervisor Prof. Matthew Johnson and co-supervisor Dr. Brian Crosland for supporting me continuously throughout my master's research and helping me out by answering my never-ending questions. With their guidance, I was able to conclude my research and present this thesis. I could not have imagined having better advisors and mentors for my master's research.

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Statistical study on soot volume fractions of buoyant turbulent diffusion fires

Gao

et al. 2022

Fire and Materials

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The statistical soot properties of buoyant turbulent diffusion propane fire were experimentally and theoretically studied with different fuel sooting tendencies by nitrogen addition. Results show that nitrogen addition decreases the instantaneous soot volume fraction and increases soot intermittency. The combination of these two factors together leads to a decrease in mean soot volume fraction when nitrogen is added. Both radially integrated and the total soot volume fraction decrease with nitrogen addition. The radially integrated soot volume fraction is found to be a function of fuel concentration. A dimensionless correlation is proposed to predict the total soot volume fraction based on theoretical analysis and in good agreement with the experimental data. The results could provide guidance for predicting soot yield for buoyant turbulent fires.

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The effect of exit Reynolds number on soot volume fraction in turbulent non-premixed jet flames

Cited by 33 publications

References 31 publications

Experimental Investigation of Soot Production and Oxidation in a Lab-Scale Rich–Quench–Lean (RQL) Burner

Experimental Investigation of Soot Production and Oxidation in a Lab-Scale Rich–Quench–Lean (RQL) Burner

Application of an Optical Diagnostic (LII/ELS) to Measure Soot Formation Trends within Turbulent Buoyant Non-Premixed Flames

Statistical study on soot volume fractions of buoyant turbulent diffusion fires

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