Turbulent mixing in three-dimensional droplet arrays

Zoby, M. R. G.; Navarro‐Martinez, S.; Kronenburg, A.; Marquis, A. J.

doi:10.1016/j.ijheatfluidflow.2011.03.006

Cited by 19 publications

(3 citation statements)

References 30 publications

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“…The data samples are taken from a line in the transverse direction at two downstream positions of l 1 = 2.3D and l 2 = 1.3D from the droplet centre, as shown in figure 10(a). It is known that the fuel-vapour field in the Z space in the wake of a droplet takes a similar form to the gaseous fuel field of a laminar diffusion flame in the Z space (Zoby et al 2011a). The conditional mean χ 1 | Z 1 , or simplified as χ | Z in this subsection, downstream of an evaporating fuel droplet has been modelled using an error function profile as (Peters 2000;Hasse & Peters 2005;Zoby et al 2011a) is the inverse complementary error function and Z max is the maximum mixture fraction value.…”

Section: 22mentioning

confidence: 99%

“…The conditional mean χ 1 | Z 1 , or simplified as χ | Z in this subsection, downstream of an evaporating fuel droplet has been modelled using an error function profile as (Peters 2000;Hasse & Peters 2005;Zoby et al 2011a) is the inverse complementary error function and Z max is the maximum mixture fraction value. Another proposed model is (Zoby et al 2011a) χ…”

Section: 22mentioning

confidence: 99%

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Puffing-enhanced fuel/air mixing of an evaporating -decane/ethanol emulsion droplet and a droplet group under convective heating

et al. 2016

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Puffing of a decane/ethanol emulsion droplet and a droplet group under convective heating and its effects on fuel/air mixing are investigated by direct numerical simulation that resolves all of the liquid/gas and liquid/liquid interfaces. With distinct differences in the boiling point between decane and ethanol, the embedded ethanol sub-droplets can be superheated and boil explosively. Puffing, i.e. ejection of ethanol vapour, occurs from inside the parent decane droplet, causing secondary breakup of the droplet. The ejected ethanol vapour mixes with the outer gas mixture composed of air and vapour of the primary fuel decane, and its effects on fuel/air mixing can be characterised by the scalar dissipation rates (SDRs). For the primary-fuel SDR, the cross-scalar diffusion due to ethanol vapour puffing plays a dominant role in enhancing the micromixing. When the vapour ejection direction is inclined towards the wake direction, the wake is elongated, but the shape of the stoichiometric mixture fraction isosurface is not changed much, indicating a limited effect on droplet grouping in a spray. On the other hand, when the ejection direction is inclined towards the transverse direction, the stoichiometric surface is pushed further away in the transverse direction, and its topology is changed by the puffing. The trajectories of ejected ethanol vapour pockets can be predicted by the correlation obtained for a jet in cross-flow, and the vapour pockets may reach a few diameters away from the droplet. Therefore, in a multiple-droplet configuration, the transverse ethanol vapour ejection due to puffing may transiently change the droplet grouping characteristics. In simulation cases with multiple droplets, the interaction changing the droplet grouping due to puffing has been confirmed, especially for droplets in the most upstream position in a spray. This implies that puffing should be accurately included in the mixing and combustion modelling of such a biofuel-blended diesel spray process.

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Section: 22mentioning

confidence: 99%

Section: 22mentioning

confidence: 99%

Puffing-enhanced fuel/air mixing of an evaporating -decane/ethanol emulsion droplet and a droplet group under convective heating

et al. 2016

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“…[26,27,28]. The other approach fully-resolves the liquid phase with the limitation of only simulating a few tiny droplets [29,30,31,32,33].…”

Section: Introductionmentioning

confidence: 99%

Identification of local extinction and prediction of reignition in a spark-ignited sparse spray flame using data mining

Wandel

2018

Combustion and Flame

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Direct Numerical Simulations (DNS) of droplet fields which are ignited using a spark are investigated to deduce any behaviour that distinguishes between the cases where successful flame propagation occurs and where a flame ignites but subsequently extinguishes. At the instant the spark was deactivated, some of the studied cases displayed no local extinction, others showed some local extinction (one with reignition and the rest with global extinction) and the rest showed global extinction. The gaseous field at this instant was analysed using the data mining technique the Gaussian Mixture Model on each case separately; this method groups data points, enabling distinction between the various behaviours. The results from this analysis showed that in the case with local extinction-reignition, the regions of space near the flame kernel which produced local quenching were caused by evaporating droplets. These regions of local quenching were relatively small compared to the strong flame front surrounding them; the regions of local quenching were also relatively far from the centre of the flame kernel. In contrast, in cases with local then global extinction, the droplets created regions which were extensions of the relatively-small flame front, and these regions behaved in a similar manner to the flame propagation. As a consequence, these cases were unable to support a self-sustaining flame. Such distinctive behaviour promises opportunities to detect situations where global extinction is imminent and implement appropriate control strategies to prevent global extinction.

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A Resolved Simulation Study on the Interactions Between Droplets and Turbulent Flames Using OpenFOAM

Wang

Chu

Kronenburg

et al. 2018

High Performance Computing in Science and Engineering ' 17

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Turbulent mixing in three-dimensional droplet arrays

Cited by 19 publications

References 30 publications

Puffing-enhanced fuel/air mixing of an evaporating -decane/ethanol emulsion droplet and a droplet group under convective heating

Puffing-enhanced fuel/air mixing of an evaporating -decane/ethanol emulsion droplet and a droplet group under convective heating

Identification of local extinction and prediction of reignition in a spark-ignited sparse spray flame using data mining

A Resolved Simulation Study on the Interactions Between Droplets and Turbulent Flames Using OpenFOAM

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