Numerical experiments on the vortex-flame interactions in a jet diffusion flame

Takahashi, Fumiaki; Katta, Vishwanath R.

doi:10.2514/6.1993-456

Cited by 6 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The flame base, presumably sustained by a laminar premixed flame structure, cannot propagate against the incoming flow and is ultimately blown off or lifted. On the other hand, the OH* chemiluminescence imaging suggests that the flame detachment mechanism in the decreasing region is controlled by local flame extinction due to high hydrodynamic strain, which is in line with previous observations underlining the importance of shear-generated vortices in the stability of diffusion jet flames [44]. In the latter case, downstream extinction by strain occurs close to the break point of the turbulent jet before reaching lean flammability conditions in the burner rim wake, hence explaining the annular flame structure observed in Fig.…”

Section: 3supporting

confidence: 76%

Stability characteristics of non-premixed turbulent jet flames of hydrogen and syngas blends with coaxial air

Hwang

Bouvet

Sohn

et al. 2013

International Journal of Hydrogen Energy

View full text Add to dashboard Cite

Section: 3supporting

confidence: 76%

Stability characteristics of non-premixed turbulent jet flames of hydrogen and syngas blends with coaxial air

Hwang

Bouvet

Sohn

et al. 2013

International Journal of Hydrogen Energy

View full text Add to dashboard Cite

“…Consequently, it would be important to characterize the effect of replacing ambient air by ambient nitrogen on the structure of RC and IC flames. 21 We intend to examine this issue in a future investigation. Figure 6 contains a comparison of the phase-matched experimental and simulated images for an IC flame established at conditions corresponding to Figs.…”

Section: Global Flame Structurementioning

confidence: 99%

A numerical and experimental investigation of “inverse” triple flames

Puri

Qin

2001

Physics of Fluids

View full text Add to dashboard Cite

Tribrachial or triple flames represent a class of partially premixed flames that generally contain three spatially distinct but synergistically coupled reaction zones, namely a rich premixed, a lean premixed, and a nonpremixed reaction zone. The generally considered flow arrangement for burner-stabilized triple flames involves a rich mixture issuing from a central port and a lean mixture from two outer ports, which we call a reference configuration ͑RC͒. Herein, we examine an inverse configuration ͑IC͒ in which a fuel-lean stream is flanked by two fuel-rich streams. The reaction zone topology in this configuration is richer and more complex compared to that in a RC flame. A numerical-experimental investigation is conducted to characterize the fundamental differences and similitude between the RC and IC methane-air triple flames in both spatial and mixture fraction based coordinates. The detailed structure of IC triple flames and their response to variations in the rich and lean equivalence ratios are examined. Finally, the transient behavior of the flames in both configurations is described. The IC and RC flames have markedly different spatial structures. In the inverse configuration, the global flame contains five reaction zones. The predicted and measured topologies of the various reaction zones are in excellent agreement. The modified mixture fraction ͑͒ is found to be effective in characterizing the structure of both RC and IC flames. The scalar profiles in terms of clearly illustrate the similitude between the two flames. The three reaction zones in the RC flame have a structure that is similar to that of the corresponding five reaction zones of the IC flame. The two nonpremixed ͑or the two rich premixed reaction zones͒ in the IC flames are not differentiated in terms of. Both the flames are subjected to a buoyancy-induced instability at normal gravity that generates large vortex structures, which cause the reaction zones to flicker. The flame-vortex interaction is initiated in the nonpremixed reaction zone for the IC flame and in the lean premixed reaction zone for the RC flame. Consequently, the IC flame flickers with higher amplitude but lower frequency as compared to the RC flame. There is good agreement between the measured and predicted flickering frequencies for the two flames. As rich is increased, the height of the two rich premixed reaction zones in the IC flames increases, their tips open, and the chemical activity in these zones decreases. While the oscillation frequency is essentially constant, the oscillation amplitude increases as rich is increased. The effect of increasing lean is to enhance chemical activity in the lean premixed zone. However, the two rich premixed zones and the outer nonpremixed zone are relatively unaffected by variations in lean. The oscillation amplitude and frequency also remain unaffected by variations in lean .

show abstract

“…The flame-vortex interactions contains many of the fundamental aspects of the coupling between fluid dynamics and combustion that could be investigated with more controllable conditions than are possible under direct investigations of turbulent flames [9]. In addition, the interactions between the large vortices generated in the shear layer and flame zone are of essential importance because they are related to various aspects of combustion phenomena such as instability and transient effects of a turbulent flame, flame stability, and local extinction [10]. Thus, many investigations have looked closely at the interactions between flames and single vortices; this system has characteristics similar to those of turbulent flames [11,12].…”

Section: Introductionmentioning

confidence: 99%