A Model for the Effects of Mixing on the Autoignition of Turbulent Flows

Mastorakos, Epaminondas; Cruz, A. Pires da; Baritaud, T.; Poinsot, Thiérry

doi:10.1080/00102209708935661

Cited by 36 publications

(21 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…First-order closure for autoignition problems has been found accurate to within 10-20% [26,30] because the first appearance of autoignition sites are related to low values of the scalar dissipation rate, the fluctuations of which generate substantial conditional fluctuations of the temperature. In practice, because quite complex chemistry must be used for autoignition and because practical calculations are costly, especially if emphasis is put on the spatial resolution and the physical-space transport of the conditional averages, it is useful to examine first order initially.…”

Section: Governing Equationsmentioning

confidence: 98%

“…Successful use of CMC for autoignition problems in simplified flow fields with both first- [25] and second-order [26] closure of the chemical source term has been reported, whereas its applicability to spray autoignition with first-order closure has also been shown [27,28]. In principle, a proper account of turbulence-chemistry interactions throughout the autoignition phase needs to include fluctuations of the scalar dissipation rate [29,30], as in second-order CMC [26]. In practice, however, the computationally simpler first-order closure must be explored for engine calculations before the added complexity and cost of the second-order approach are justified.…”

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Simulations of spray autoignition and flame establishment with two-dimensional CMC

Wright¹,

Paola²,

Boulouchos³

et al. 2005

Combustion and Flame

116

View full text Add to dashboard Cite

Section: Governing Equationsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

Simulations of spray autoignition and flame establishment with two-dimensional CMC

Wright¹,

Paola²,

Boulouchos³

et al. 2005

Combustion and Flame

116

View full text Add to dashboard Cite

“…On the other hand, Mastorakos et al [2] demonstrated by performing simulations with the same DNS code as in Ref. [1] that enhanced turbulence (that is shorter τ turb ) promoted a slight acceleration of autoignition.…”

Section: Introductionmentioning

confidence: 99%

“…Simulations have been performed with simple and complex chemistry in two- [1][2][3][4][5][6][7], but also three-dimensional turbulence [8,9]. Specifically, the DNS revealed that autoignition was always observed at a well-defined value inhibiting/delaying effect on the pre-ignition chemistry, and hence on the appearance of autoignition, depending on the evolution of the scalar dissipation and its fluctuations".…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Effects of Turbulence and Mixing on Autoignition Chemistry

Markides

Mastorakos

2010

Flow Turbulence Combust

View full text Add to dashboard Cite

The autoignition of acetylene released into a turbulent coflow of hot air has been the object of a recent experimental study to supplement previous work for hydrogen and n-heptane. As with hydrogen and n-heptane, autoignition appears in the form of localised spots. Here, we present new information concerning the effects of turbulence intensity, turbulent lengthscale and injector diameter on the location of autoignition. The effects of these parameters on inhomogeneous autoignition have not been investigated experimentally before. The present study establishes that increasing the bulk velocity, while keeping the lengthscale constant, increases autoignition length.For the same turbulence intensity, the autoignition length increases as the injector diameter increases and as the turbulent lengthscale decreases. A simultaneous decrease in turbulence intensity and increase in lengthscale causes a reduction in autoignition length. Further, the frequency of appearance of the autoignition spots was measured. It was found to increase when autoignition occurred closer to the injector, and also at higher velocities. The observed trends are consistent with expectations arising from the dependence of the mixture fraction and scalar dissipation on the geometrical and flow parameters. The data can be used for the validation of turbulent combustion models.

show abstract

“…Modelling work was carried by Mastorakos et al [6] to evaluate the effect of mixing on autoignition. The results for laminar autoignition from Liñan and Crespo [7] and Thevenin and Candel [8] were extended to turbulent flows.…”

mentioning

confidence: 99%

Second-Order Conditional Moment Closure Simulations of Autoignition of an n-heptane Plume in a Turbulent Coflow of Heated Air

Paola

Kim

Mastorakos

2008

Flow Turbulence Combust

Self Cite

View full text Add to dashboard Cite

Autoignition of an n-heptane plume in a turbulent coflow of heated air has been studied using the conditional moment closure (CMC) method with a secondorder closure for the conditional chemical source term. Two different methodologies have been considered: (i) the Taylor expansion method, in which the second order correction was based on the solution of the full covariance matrix for the 31 reactive species in the chemical mechanism and hence was not limited to a few selected reactions, and (ii) the conditional PDF method, in which only the temperature conditional variance equation has been solved and its PDF assumed to be a β-function. The results compare favorably with experiment in terms of autoignition location. The structure of the reaction zone in mixture fraction space has been explored. The relative performance of the two methodologies is discussed.

show abstract

A Model for the Effects of Mixing on the Autoignition of Turbulent Flows

Cited by 36 publications

References 26 publications

Simulations of spray autoignition and flame establishment with two-dimensional CMC

Simulations of spray autoignition and flame establishment with two-dimensional CMC

Experimental Investigation of the Effects of Turbulence and Mixing on Autoignition Chemistry

Second-Order Conditional Moment Closure Simulations of Autoignition of an n-heptane Plume in a Turbulent Coflow of Heated Air

Contact Info

Product

Resources

About