Measurements of temperature and concentration fluctuations in turbulent diffusion flames using pulsed raman spectroscopy

Drake, Michael C.; Lapp, M.; Penney, C. M.; Warshaw, S. D.; Gerhold, B.W.

doi:10.1016/s0082-0784(81)80154-3

Cited by 51 publications

(17 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In both cases the peak in the acetylene formation layer is slightly to the rich side of stoichiometric, as expected. Figures 4,5,6,7,8,9 and 10 show the corresponding plots for, respectively, Hydrogen radical H, Hydrogen molecule H 2 , Oxygen radical O, Hydroxyl radical OH, Carbon monoxide CO, Carbon dioxide CO 2 , and water vapour H 2 O.…”

Section: Comparative Dns Study Of the Effect Of Non-unity Lewis Numbersmentioning

confidence: 99%

See 1 more Smart Citation

The Effect of Preferential Diffusion on the Soot Initiation Process in Ethylene Diffusion Flames

Malik

Løvås

Mauß

2011

Flow Turbulence Combust

View full text Add to dashboard Cite

The influence of differential diffusion of chemical species in the soot initiation process in turbulent flows is investigated through Direct Numerical Simulations coupled to a compact global chemical mechanisms for ethylene (C 2 H 4 ) flame combustion (Løvås et al., Combust Sci Tech 182(11):1945-1960 featuring the important reaction steps for acetylene production. Our focus is on the formation of acetylene (C 2 H 2 ) which is one of the most important species indicative of soot formation layers, especially in relation to the location of the H and H 2 layers. The effect of preferential diffusion is assessed by comparison of results from unity and non-unity Lewis number simulations. The results indicate that under moderate turbulent conditions, where preferential diffusion effects become prominent, and with the global scheme used preferential diffusion greatly enhances the spread of the radical H whose peak value in mass fraction is reduced by a factor of about two; the spread of H 2 is also enhanced though to a lesser extent. Importantly, the H and H 2 spread into a range of mixture fraction Z between 0.2 and 0.3 which contains the soot formation range, supporting the hypothesis that soot formation is enhanced by preferential diffusion. Nevertheless, the acetylene formation layers themselves show little adjustment in the presence of non-unity Lewis numbers suggesting that the acetylene formation is dominated under the current conditions by the direct thermal Flow Turbulence Combust (2011) 87:293-312 decomposition of ethylene to acetylene in the global chemistry used. The specific F i factors that appear in flamelet models are explicitly computed; only F H , F H2 and F CO show appreciable differences on the fuel lean range of mixture fraction due to nonunity Lewis numbers, suggesting that the effects of non-unity Lewis numbers could be incorporated by a selective inclusion of only a few of the F i factors in order to save computational time.

show abstract

Section: Comparative Dns Study Of the Effect Of Non-unity Lewis Numbersmentioning

confidence: 99%

“…Drake et al [8] found that differential diffusion affected hydrogen and nitrogen concentrations in H2-air diffusion flames of low turbulence levels. Smith et al [28] observed differential diffusion effects on hydrogen element mixture fraction at Reynolds numbers up to Re = 30, 000.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Preferential Diffusion on the Soot Initiation Process in Ethylene Diffusion Flames

Malik

Løvås

Mauß

2011

Flow Turbulence Combust

View full text Add to dashboard Cite

show abstract

“…4'68 The evidence for this, however, is limited and the difference between conventional and density-weighted averages can be large The behavior of a particular species or density depends on the state relationship of the reactant system; therefore, we consider mixture fraction as a representative scalar property to examine the differences between these averages. From the basic definitions (f-.7")If= -(TIJ'Xp'Ip)R,,:,.. (14) At the fast-reaction limit, the difference can also be conveniently stated in terms of mixture fraction and the state relationship for density, as follows:…”

Section: Other Scalar Propertiesmentioning

confidence: 99%

Fast reaction nonpremixed combustion

Faeth

Samuelsen

1986

Progress in Energy and Combustion Science

View full text Add to dashboard Cite

Abstract--Recent measurements in turbulent, single-phase, reacting flows are reviewed. Attention is confined to nonpremixed flows at the fast reaction limit, which is defined as conditions where rates of reaction are fast enough to maintain local equilibrium. Reactant combinations considered include: hydrogen/air, carbon monoxide/air, hydrogen/fluorine, nitric oxide/ozone, acid/base (in liquids) and the dissociation of nitrogen tetroxide in warm air. Criteria for the fast-reaction limit, as well as the laminar flamelet concept, are discussed in some detail. Other aspects of measurements in these systems are also discussed, e.g. effects of initial and boundary conditions; types of averaging; and the interpretation of velocity, temperature and other scalar property measurements. Existing measurements in round free jets, plane free shear layers and wall boundary layers are summarized and discussed.

show abstract

“…28,29 Experimental studies of differential diffusion are reported for both reacting and non-reacting flows. For example, differential diffusion in non-reacting flows is explored by Drake et al 30,31 , Masri et al 32 , Smith et al 33 and Dibble and Long 34 . While reacting flows are considered by Smith et al 35 and Bergmann et al 36 Most of the above cited works are for non-premixed combustion, which is also the focus of the present research, but it is noted that the effect of differential diffusion on premixed flames are significant and discussed in many publications (e.g., Kuznetsov and Sabelnikov 15 ) but not specifically considered here.…”

Section: Introductionmentioning

confidence: 99%

A multiple mapping conditioning model for differential diffusion

2014

View full text Add to dashboard Cite

This work introduces modeling of differential diffusion within the multiple mapping conditioning (MMC) turbulent mixing and combustion framework. The effect of differential diffusion on scalar variance decay is analyzed and, following a number of publications, is found to scale as Re−1/2. The ability to model the differential decay rates is the most important aim of practical differential diffusion models, and here this is achieved in MMC by introducing what is called the side-stepping method. The approach is practical and, as it does not involve an increase in the number of MMC reference variables, economical. In addition we also investigate the modeling of a more refined and difficult to reproduce differential diffusion effect – the loss of correlation between the different scalars. For this we develop an alternative MMC model with two reference variables but which also makes use of the side-stepping method. The new models are successfully validated against DNS results available in literature for homogenous, isotropic two scalar mixing.

show abstract

Measurements of temperature and concentration fluctuations in turbulent diffusion flames using pulsed raman spectroscopy

Cited by 51 publications

References 7 publications

The Effect of Preferential Diffusion on the Soot Initiation Process in Ethylene Diffusion Flames

The Effect of Preferential Diffusion on the Soot Initiation Process in Ethylene Diffusion Flames

Fast reaction nonpremixed combustion

A multiple mapping conditioning model for differential diffusion

Contact Info

Product

Resources

About