A Concentric Flow Conical Nozzle Burner for Highly Stabilized Partially Premixed Flames

Mansour, Mohy S.

doi:10.1080/00102200008952130

Cited by 45 publications

(25 citation statements)

References 17 publications

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“…The stability characteristics of an earlier version of the CFCN burner indicated that partially premixed flames are more stable than premixed or non-premixed flames, and that the level of partial premixing is a critical flame stability parameter [4]. The flames created within the CFCN burner exhibit high stability levels because of the conical shape of the nozzle and the degree of partial premixing.…”

Section: Stability Limits Selected Flames and Flame Appearancementioning

confidence: 99%

“…Different techniques have been used to stabilize these flames at the nozzle exit. Examples of these techniques include the partially premixed flames [2][3][4][5], the swirl flame [6][7][8][9], the pilot flame for non-premixed [10,11]; premixed [12], and flame holder [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…PPF's contain multiple reaction zones which are spatially separated but actually coupled through turbulence-chemistry interactions between them, and the flame structure is strongly dependent upon these interactions [1]. Partially premixed flames are likely to be more stable than premixed or non-premixed flames [2][3][4]. Different techniques have been used to stabilize these flames at the nozzle exit.…”

Section: Introductionmentioning

confidence: 99%

“…A Concentric Flow Conical Nozzle (CFCN) burner has been developed and modified by Mansour [4,15] in order to create well-controlled and highly stabilized partially premixed flames. The higher stability characteristic of the CFCN burner, as compared to a nozzle jet burner, is due to the conical shape of the nozzle and control of the level of partial premixing.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow

Elbaz

Zayed

Samy

et al. 2016

Experimental Thermal and Fluid Science

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The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow KAUST Repository a b s t r a c tThe stability limits, the stabilization mechanism, and the flow field structure of highly stabilized partially premixed methane flames in a concentric flow conical nozzle burner with air co-flow have been investigated and presented in this work. The stability map of partial premixed flames illustrates that the flames are stable between two extinction limits. A low extinction limit when partial premixed flames approach non-premixed flame conditions, and a high extinction limit, with the partial premixed flames approach fully premixed flame conditions. These two limits showed that the most stable flame conditions are achieved at a certain degree of partial premixed. The stability is improved by adding air co-flow. As the air co-flow velocity increases the most stable flames are those that approach fully premixed. The turbulent flow field of three flames at 0, 5, 10 m/s co-flow velocity are investigated using Stereo Particle Image Velocimetry (SPIV) in order to explore the improvement of the flame stability due to the use of air co-flow. The three flames are all at a jet equivalence ratio (U j ) of 2, fixed level of partial premixing and jet Reynolds number (Re j ) of 10,000. The use of co-flow results in the formation of two vortices at the cone exit. These vortices act like stabilization anchors for the flames to the nozzle tip. With these vortices in the flow field, the reaction zone shifts toward the reduced turbulence intensity at the nozzle rim of the cone. Interesting information about the structure of the flow field with and without co-flow are identified and reported in this work.

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Section: Stability Limits Selected Flames and Flame Appearancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow

Elbaz

Zayed

Samy

et al. 2016

Experimental Thermal and Fluid Science

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“…To generate turbulent partially premixed flames at high turbulent intensities, the concentric flow conical flame burner described in [9][10][11] is adopted. Previous studies, at a particular partial premixing condition, have shown that the flame is stabilized in the cone due to the presence of a triple flame at the leading flame front in the recirculation region induced by the entrainment of ambient air to the cone [12,13].…”

Section: Introductionmentioning

confidence: 99%

Effect of Partial Premixing on Stabilization and Local Extinction of Turbulent Methane/Air Flames

Baudoin

Bai

Yan

et al. 2012

Flow Turbulence Combust

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The stabilization characteristics and local extinction structures of partially premixed methane/air flames were studied using simultaneous OH-PLIF/PIV techniques, and large eddy simulations employing a two-scalar flamelet model. Partial premixing was made in a mixing chamber comprised of two concentric tubes, where the degree of partial premixing of fuel and air was controlled by varying the mixing length of the chamber. At the exit of the mixing chamber a cone was mounted to stabilize the flames at high turbulence intensities. The stability regime of flames was determined for different degree of partial premixing and Reynolds numbers. It was found that in general partially premixed flames at low Reynolds numbers become more stable when the level of partial premixing of air to the fuel stream decreases. At high Reynolds numbers, for the presently studied burner configuration there is an optimal partial premixing level of air to the fuel stream at which the flame is most stable. OH-PLIF images revealed that for the stable flames not very close to the blowout regime, significant local extinction holes appear already. By increasing premixing air to fuel stream successively, local extinction holes grow in size leading to eventual flame blowout. Local flame extinction was found to frequently attain to locations where locally high velocity flows impinging to the flame. The local flame extinction poses a future challenge for model simulations and the present flames provide a possible test case for such study. IntroductionPartially premixed flames, defined as flames where the compositions of the mixture vary from fuel-rich to stoichiometry and fuel-lean [1], are found in many engineering applications. In modern internal combustion engines using multiple injections of fuel to control emissions, partially premixed charge are typically formed before ignition. Due to the presence of rich, lean and stoichiometric mixtures in partially premixed flames, lean and rich premixed flame fronts exist in the leading front followed by the main diffusion flame [2][3][4]. The combustion characteristics of partially premixed flames are not well understood and modeling of partially premixed flames is challenging [1,2,5].Local flame quenching and re-ignition in laminar and turbulent flames is an issue that has attracted the attention of recent research. Once a non-premixed flame is locally quenched, edge flame exists at the extremity of the reaction zones, where the flame progressively evolves to partially premixed flames [6]. The critical strain rate for quenching of partially premixed flames is influenced by the degree of partial premixing. For laminar flames, experimental and theoretical studies [7,8] using a counter flow configuration showed that partial premixing of fuel to the air stream can increase the quenching strain rate, whereas partial premixing of air to the fuel stream can decrease the critical quenching strain rate. In high Reynolds number turbulent flames, the quenching process is more complex. In an

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Effect of Multilateral Jet Mixing on Stability and Structure of Turbulent Partially-Premixed Flames

Thong

Dally

Medwell

et al. 2017

Flow Turbulence Combust

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A Concentric Flow Conical Nozzle Burner for Highly Stabilized Partially Premixed Flames

Cited by 45 publications

References 17 publications

The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow

The flow field structure of highly stabilized partially premixed flames in a concentric flow conical nozzle burner with coflow

Effect of Partial Premixing on Stabilization and Local Extinction of Turbulent Methane/Air Flames

Effect of Multilateral Jet Mixing on Stability and Structure of Turbulent Partially-Premixed Flames

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