The localised forced ignition and early stages of flame development in a turbulent planar jet

d’Auzay, Charles Turquand; Chakraborty, Nilanjan

doi:10.1016/j.proci.2020.07.148

Cited by 8 publications

(16 citation statements)

References 28 publications

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“…Moreover, the flame structure resulting from localised forced ignition of turbulent gaseous mixing layer and droplet-laden mixtures using single-step Arrhenius-type chemistry 24,55,56 are qualitatively similar to those obtained from detailed chemistry simulations. 57,58 It was demonstrated by Turquand d'Auzay et al 31 that the edge flame propagation statistics for forced ignition of turbulent mixing layers for the chemical and transport models used in this article have been found to be qualitatively similar to the detailed chemistry DNS studies. [59][60][61] It is worth noting that pioneering analytical studies [62][63][64][65][66] on ignition have been conducted for singlestep irreversible Arrhenius type chemistry.…”

Section: Thermo-chemistrysupporting

confidence: 53%

“…This is attributed to the lower flame speed of the stoichiometric diluted mixture, which directly affects the resulting edge flame speed (see equation ( 19)) and the height at which an equilibrium can be found between the flame and flow movements in a mean sense as detailed below. In particular, the onset of stabilisation was reported by Turquand dAuzay and Chakraborty 31 for the undiluted mixture, but a clear indication of flame stabilisation cannot be ascertained for the cases with ψ = 0.1 and ψ = 0.2. This also suggests that the probability of obtaining flame stabilisation for CH 4 /CO 2 jet flames is likely smaller than that in the case of undiluted methane-air jets.…”

Section: Evolution Of the Flame Heightmentioning

confidence: 90%

“…CO 2 concentration in the fuel blend) on the kernel growth and its transition towards a fully stable flame resulting from the forced ignition of a turbulent jet. This is achieved by extending the present authors' previous DNS analysis of the localised forced ignition of a turbulent planar jet 31 to the use of various compositions in the fuel stream. The effects of CO 2 concentration in the fuel blend on the reaction kinetics are accounted for by using a two-step chemical mechanism.…”

Section: Introductionmentioning

confidence: 86%

“…Ahmed and Mastorakos 28 also demonstrated the importance of edge flame propagation on the flame development and stabilisation, which has been confirmed by various DNS studies of lifted jet flames. 29–33 This experimental database has also been extensively used to assess the validity of various ignition and flame propagation models within the Large Eddy Simulation (LES) 34–37 and Reynolds-Averaged Navier-Stokes frameworks. 38,39 Previous numerical studies looked at ignition of shear layers and highlighted the importance of edge flame on the kernel growth using DNS 40,41 as well as the kernel position in mixture fraction space using LES.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A direct numerical simulation analysis of localised forced ignition in turbulent slot jets of CH4/CO2 blends

d’Auzay

Chakraborty

2023

International Journal of Spray and Combustion Dynamics

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The early stages of flame evolution following successful localised forced ignition of different CH[Formula: see text]/CO[Formula: see text] blends in a slot jet configuration have been analysed using three-dimensional direct numerical simulations. The simulations have been conducted for three different concentration levels of CO[Formula: see text] in the fuel blend composed of CH[Formula: see text] and CO[Formula: see text] (ranging from 0% to 20% by volume). The effects of CO[Formula: see text] concentration have been analysed based on five different energy deposition scenarios which include situations where the mean mixture composition at the ignitor varies, but not its location in space, whereas other cases represent the scenarios where the mean mixture composition within the energy deposition region remains constant, but its spatial location changes with CO[Formula: see text] concentration. The most favourable region for successful flame development following thermal runaway, from the mixture composition standpoint (i.e. the highest flammability factor), has been found to be displaced close to the nozzle with an increase in CO[Formula: see text] concentration. The flame development following thermal runaway exhibits initial growth of hot gas kernel followed by downstream advection and eventual flame propagation along with radial expansion with a possibility of flame stabilisation irrespective of the level of CO[Formula: see text] concentration. The triple flame propagation has been found to play a key role in the upstream flame propagation and eventual stabilisation. The orientation of the local flame normal plays a key role in the flame stabilisation. The lift off height has been found to increase with increasing CO[Formula: see text] concentration which also adversely affect flame stabilisation for high levels of CO[Formula: see text] concentration.

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Section: Thermo-chemistrysupporting

confidence: 53%

Section: Evolution Of the Flame Heightmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A direct numerical simulation analysis of localised forced ignition in turbulent slot jets of CH4/CO2 blends

d’Auzay

Chakraborty

2023

International Journal of Spray and Combustion Dynamics

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“…A number of analytical (Dold 1989;Hartley and Dold 1991;Ruan et al 2012;Buckmaster 2002), experimental (Chung 2007;Ko and Chung 1999;Takita et al 2003Takita et al , 2004Won et al 2005) and numerical (Echekki and Chen 1998;Chen 1999, 2001;Yoo and Im 2005) studies have focused on the structure and propagation characteristics of the flames arising from the localised forced ignition of laminar inhomogeneous mixtures. This type of flames is characterised by a self-propagating edge flame stabilised around the stoichiometric mixture fraction surface and plays a pivotal role in flame stabilisation and extinction (Chung 2007;Domingo and Vervisch 1996;Karami et al 2015;Turquand d'Auzay and Chakraborty 2021;Karami et al 2016). In the presence of low strain rates, the flame is tribrachial with a leading edge stabilised between two premixed flames (one rich and one lean) with tail of non-premixed (diffusion) flame.…”

Section: Introductionmentioning

confidence: 99%

Effects of Biogas Composition on the Edge Flame Propagation in Igniting Turbulent Mixing Layers

Turquand

Papapostolou

Chakraborty

2020

Flow Turbulence Combust

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Three-dimensional compressible Direct Numerical Simulations have been used to investigate the localised forced ignition of statistically planar biogas/air mixing layers for different levels of turbulence intensity and biogas composition. The biogas is represented by a $$\hbox {CH}_4$$ CH 4 /$$\hbox {CO}_2$$ CO 2 mixture and a two-step mechanism capturing the variation of the unstrained laminar flame speed with equivalence ratio and $$\hbox {CO}_2$$ CO 2 dilution was used. The mixture composition was found to significantly affect the flame kernel development which was reflected in the diminished growth rate of the burned gas volume with increasing $$\hbox {CO}_2$$ CO 2 dilution. A successful ignition of $$\hbox {CH}_4$$ CH 4 /$$\hbox {CO}_2$$ CO 2 /air mixing layer gives rise to a tribrachial flame structure involving fuel-rich and lean premixed branches on either side of the diffusion flame stabilised on the stoichiometric mixture fraction iso-surface. The most probable edge flame speed decreases in time and converges to a value that is at most equal to its laminar theoretical limit, and can even locally become negative for large values of the dilution and/or turbulence intensity. The decomposition of the edge flame speed showed a negligible or negative contribution of the mixture fraction surface displacement speed, while the displacement speed of the fuel mass fraction surface appeared as the dominant contributor. Finally, the edge flame speed dependences to the fuel mass fraction and mixture fraction gradients, fuel mass fraction iso-surface curvature and tangential strain rate have been analysed and found, within the dilution values considered, qualitatively similar to those of undiluted mixtures regardless of the amount of $$\hbox {CO}_2$$ CO 2 , although quantitative differences were observed.

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A-Priori Validation of Scalar Dissipation Rate Models for Turbulent Non-Premixed Flames

Sitte

Turquand

Giusti

et al. 2020

Flow Turbulence Combust

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The modelling of scalar dissipation rate in conditional methods for large-eddy simulations is investigated based on a priori direct numerical simulation analysis using a dataset representing an igniting non-premixed planar jet flame. The main objective is to provide a comprehensive assessment of models typically used for large-eddy simulations of non-premixed turbulent flames with the Conditional Moment Closure combustion model. The linear relaxation model gives a good estimate of the Favre-filtered scalar dissipation rate throughout the ignition with a value of the related constant close to the one deduced from theoretical arguments. Such value of the constant is one order of magnitude higher than typical values used in Reynolds-averaged approaches. The amplitude mapping closure model provides a satisfactory estimate of the conditionally filtered scalar dissipation rate even in flows characterised by shear driven turbulence and strong density variation.

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The localised forced ignition and early stages of flame development in a turbulent planar jet

Cited by 8 publications

References 28 publications

A direct numerical simulation analysis of localised forced ignition in turbulent slot jets of CH4/CO2 blends

A direct numerical simulation analysis of localised forced ignition in turbulent slot jets of CH4/CO2 blends

Effects of Biogas Composition on the Edge Flame Propagation in Igniting Turbulent Mixing Layers

A-Priori Validation of Scalar Dissipation Rate Models for Turbulent Non-Premixed Flames

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