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

Baudoin, Eric; Bai, Xue‐Song; Yan, Beibei; Liu, C.; Yu, Rixin; Lantz, Andreas; Hosseini, Seyed Mohammad; Li, B.; Elbaz, Ayman M.; Sami, Mohamed; Li, Zhongshan; Collin, Robert; Chen, G.; Fuchs, László; Aldén, Marcus; Mansour, Mohy S.

doi:10.1007/s10494-012-9414-z

Cited by 17 publications

(12 citation statements)

References 33 publications

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“…[4,[15][16][17][18][19] for different flame conditions were without co-flow stabilization. In the present work, we introduced a co-flow parameter in order to extend this study and observe its effect on the flame stabilization mechanism within the CFCN burner at different degree of partial premixing.…”

Section: Rementioning

confidence: 99%

“…Measurements and numerical study were conducted inside and downstream the conical nozzle in order to explore the stabilization mechanism and investigate the flame structure of partially premixed flames [17,18] under different equivalence ratios and degrees of partial premixed. They [17,18] Reynolds number flames was due to a stream of air being entrained along the conical nozzle wall and heated by the flame before being entrained into the early region of the flame. Additionally, they observed a recirculation zone of hot combustion products at the conical nozzle base.…”

Section: Introductionmentioning

confidence: 99%

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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: Rementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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 track the flame front propagation, a transport equation of progress variable C is solved. The model has been applied to many simple combustor-like burners [2,[13][14][15][16][17][18], but far less attention has been paid on the performance of this model in a realistic combustor. In addition, there is a lack of comparative studies on the performance of partially premixed combustion and non-premixed models in complicated flow configurations and most comparisons are only performed in a simplified burner which provides limited confidence for applying these models to realistic gas turbine combustors.…”

mentioning

confidence: 99%

Comparative study of non-premixed and partially-premixed combustion simulations in a realistic Tay model combustor

Zhang

Ghobadian

Nouri

2017

Applied Thermal Engineering

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A comparative study of two combustion models based on non-premixed assumption and partially premixed assumptions using the overall models of Zimont Turbulent Flame Speed Closure Method (ZTFSC) and Extended Coherent Flamelet Method (ECFM) are conducted through Reynolds stress turbulence modelling of Tay model gas turbine combustor for the first time. The Tay model combustor retains all essential features of a realistic gas turbine combustor. It is seen that the non-premixed combustion model fails to predict the combustion completely due to an incorrect assumption of diffusion flame scenario invoking infinitely fast chemistry in complicated flow environments while the two partially premixed combustion models accurately predict the flame pattern in the primary region of the combustor. The ZTFSC model outperformed the ECFM model by producing a better temperature agreement with the experimental result. The latter model predicts lower temperature due to the underestimation of reaction progress. Additionally, a cross-comparison of the present RSM prediction invoking ZTFSC model with LES prediction reported in the literature is conducted. The former produces more accurate species concentration and flame pattern than the latter. This is mainly due to the incorrect assumption of nonpremixed combustion used in LES prediction reported in the literature. It is interesting to find that when nonpremixed combustion model is used for both RSM and LES predictions, the LES predicts higher temperature closer to the injection nozzle of combustor than the RSM model, though the flame shape in both cases is incorrect. This is mainly due to the fact that the traditional RANS model dissipates the energy of swirling flow too fast in the primary region of the combustor. The weaker centre recirculation zone (CRZ) created by vortex breakdown recirculate less air to the area near the injection nozzle resulting in fuel rich combustion. It indicates that the temperature difference between predicted results using RSM in conjunction with ZTFC model and experimental results can be improved by using less energy dissipating turbulence models such as scale resolving simulation (SRS). 1. Introduction The advent of Gas-Turbine for military purposes tracks back to 1940s, and it is subsequently used for aviation and later for ground level power [1]. The main challenge of aviation industries nowadays is the efficiency, stability of combustion and pollutant control, such as the emission of carbon dioxide (CO2), nitrogen oxide, sulphur dioxide and etc. In order to design combustors with desired features and meet with relevant criteria, improved understanding of turbulent combustion through both realistic experimental observation and numerical simulation and validation is required. The former alone is expensive for industries before a more cost-effective numerical prediction is performed. However, the accuracy of the numerical simulation is doubtful as it is highly dependent on the turbulence and combustion models, i.e. the mixing and chemical reactions. To i...

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“…A study [15] was conducted to investigate the effect of the premixing level on the local extinction and stabilization characteristics of the methane-air flames. Simultaneous OH-PLIF/PIV techniques and Large Eddy Simulation (LES) were used in this study.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Flame Characteristics and Stability for Conical Nozzle Burner

Dakka¹

2019

Journal of Thermal Engineering

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The stability and the mean structure of methane partially premixed conical burner flames was investigated numerically using ANSYS Fluent. The study presents and discusses the stability curves of the partially premixed flame and maps the mean flame structure based on contours of mass fraction of O2, CO and temperature. From the data obtained, it can be concluded that both premixed and non-premixed flames are less stable than the partially premixed flames. An optimum level of partially premixing was found and the flames beyond this threshold were found to be less stable. This optimum level was found, when the ratio of the mixing length to the nozzle diameter is equal to 5. At this specific degree of partially premixing, the flame exhibited triple interaction reaction zones. It was found that with an increase of the angle of the cone of the burner, the air entrainment increases which, in turns breaks the stabilization core and hence cause a reduction in the flame stability limit. The main role of the cone is to provide a protection from the surrounding environment at early phase of the reaction near the jet exit where turbulence with high intensity was observed.

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

Cited by 17 publications

References 33 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

Comparative study of non-premixed and partially-premixed combustion simulations in a realistic Tay model combustor

Numerical Analysis of Flame Characteristics and Stability for Conical Nozzle Burner

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