DNS of spark ignition and edge flame propagation in turbulent droplet-laden mixing layers

Neophytou, A.; Mastorakos, Epaminondas; Cant, RS

doi:10.1016/j.combustflame.2010.01.019

Cited by 83 publications

(98 citation statements)

References 37 publications

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“…Furthermore, Re d is the droplet Reynolds number, Sc is the Schmidt number, B d is the Spalding mass transfer number, Sh c is the corrected Sherwood number and Nu c is the corrected Nusselt number, which are defined as [21,33]: The droplets are coupled to the gaseous phase via additional source terms in the gaseous transport equations, which may be generically written as [18][19][20][21][22][23][24][25][26][27][28][29][30][31]:…”

Section: Mathematical Backgroundmentioning

confidence: 99%

“…One can furthermore define a reaction progress variable,c, based on a species mass fraction and the mixture fraction such that c rises monotonically from zero in the unburnt reactants to one in the fully burnt products. In droplet combustion it is advantageous to employ an oxidiser-based reaction progress variable, which takes the following form [19,25,27,29]:…”

Section: Mathematical Backgroundmentioning

confidence: 99%

“…The present numerical investigation employs a widely-used three-dimensional compressible DNS code SENGA [19,25,27,29,39] which solves the standard transport equations of mass, momentum, energy and species in non-dimensional form. In SENGA the spatial discretisation for the internal grid points is carried out using a 10th order central difference scheme, but the order of differentiation drops gradually to a one-sided 2nd order scheme at the non-periodic boundaries [39].…”

Section: Numerical Implementationmentioning

confidence: 99%

“…In recent times, both single-step [18][19][20][21][22][23][24][25][26][27][28][29] or detailed [30,31] chemistry based DNS analyses have contributed significantly to the physical understanding and modelling of the combustion of turbulent droplet-laden mixtures. In the aforementioned DNS studies, the gaseous phase is treated in a typical Eulerian fashion and the droplets are considered as sub-grid particles which are tracked in a Lagrangian manner.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Flame Structure and Propagation in Turbulent Flame-Droplet Interaction: A Direct Numerical Simulation Analysis

Wacks

Chakraborty

2016

Flow Turbulence Combust

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Three-dimensional Direct Numerical Simulations (DNS) in canonical configuration have been employed to study the combustion of mono-disperse droplet-mist under turbulent flow conditions. A parametric study has been performed for a range of values of droplet equivalence ratio φ d , droplet diameter a d and root-mean-square value of turbulent velocity u . The fuel is supplied entirely in liquid phase such that the evaporation of the droplets gives rise to gaseous fuel which then facilitates flame propagation into the dropletmist. The combustion process in gaseous phase takes place predominantly in fuel-lean mode even for φ d > 1. The probability of finding fuel-lean mixture increases with increasing initial droplet diameter because of slower evaporation of larger droplets. The chemical reaction is found to take place under both premixed and non-premixed modes of combustion: the premixed mode ocurring mainly under fuel-lean conditions and the non-premixed mode under stoichiometric or fuel-rich conditions. The prevalence of premixed combustion was seen to decrease with increasing droplet size. Furthermore, droplet-fuelled turbulent flames have been found to be thicker than the corresponding turbulent stoichiometric premixed flames and this thickening increases with increasing droplet diameter. The flame thickening in droplet cases has been explained in terms of normal strain rate induced by fluid motion and due to flame normal propagation arising from different components of displacement speed. The statistical behaviours of the effective normal strain rate and flame stretching have been analysed in detail and detailed physical explanations have been provided for the observed behaviour. It has been found that the droplet cases show higher probability of finding positive effective normal strain rate (i.e. combined contribution of fluid motion and flame propagation), and negative values of stretch rate than in the stoichiometric premixed flame under similar flow conditions, which are responsible for higher flame thickness and smaller flame area generation in droplet cases.

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Section: Mathematical Backgroundmentioning

confidence: 99%

Section: Mathematical Backgroundmentioning

confidence: 99%

Section: Numerical Implementationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Flame Structure and Propagation in Turbulent Flame-Droplet Interaction: A Direct Numerical Simulation Analysis

Wacks

Chakraborty

2016

Flow Turbulence Combust

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“…Recently, the spray combustion behavior has been studied by means of two-or three-dimensional direct numerical simulations (DNSs) (e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]) or largeeddy simulations (LESs) (e.g., [19][20][21][22][23]). However, the mechanism of spray combustion has not been fully understood yet.…”

Section: Introductionmentioning

confidence: 99%

Evaporation and combustion of multicomponent fuel droplets

Kitano

Nishio

Kurose

et al. 2014

Fuel

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The effects of difference in fuel components on the droplet evaporation and combustion are numerically investigated. Jet-A is used as liquid fuel, and one (n-decane)-, two (n-decane and 1,2,4-trimethyl-benzene)-and three (n-dodecane, iso-octane and toluene)-component fuels are used as the surrogate fuels of Jet-A. The results show that the evaporation of the three-component surrogate fuel becomes faster and slower than those of the one-and two-component surrogate fuels in the initial and subsequent evaporating periods, respectively. The differences in the gas temperature evolution among these three different surrogate fuels are remarkable right after the ignition, but become small with time.

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