SOOT DISTRIBUTION IN TURBULENT BLUFF BODY NEAR WAKE NON PREMIXED FLAMES

2018 ◽  
Author(s):  
Suzane Nascimento ◽  
Juan Jose Cruz Villanueva ◽  
Luís Fernando Figueira da Silva
Keyword(s):  
Bluff Body ◽  
Premixed Flames ◽  
Near Wake ◽  
Soot Distribution

scholarly journals Modelling of a Bluff-Body Stabilised Premixed Flames Close to Blow-Off

Computation ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 43
Author(s):  
Shokri Amzin ◽  
Mohd Fairus Mohd Yasin
Keyword(s):  
Bluff Body ◽  
Fluid Dynamic ◽  
Premixed Flames ◽  
Pollutant Emissions ◽  
Moment Closure ◽  
Recirculation Region ◽  
Scalar Dissipation ◽  
Average Error ◽  
Conditional Moment ◽  
Lean Premixed

As emission legislation becomes more stringent, the modelling of turbulent lean premixed combustion is becoming an essential tool for designing efficient and environmentally friendly combustion systems. However, to predict emissions, reliable predictive models are required. Among the promising methods capable of predicting pollutant emissions with a long chemical time scale, such as nitrogen oxides (NOx), is conditional moment closure (CMC). However, the practical application of this method to turbulent premixed flames depends on the precision of the conditional scalar dissipation rate,. In this study, an alternative closure for this term is implemented in the RANS-CMC method. The method is validated against the velocity, temperature, and gas composition measurements of lean premixed flames close to blow-off, within the limit of computational fluid dynamic (CFD) capability. Acceptable agreement is achieved between the predicted and measured values near the burner, with an average error of 15%. The model reproduces the flame characteristics; some discrepancies are found within the recirculation region due to significant turbulence intensity.

scholarly journals Turbulent flame-vortex dynamics of bluff-body premixed flames

2021 ◽  
Vol 223 ◽  
pp. 28-41
Author(s):  
Marissa K. Geikie ◽  
Cal J. Rising ◽  
Anthony J. Morales ◽  
Kareem A. Ahmed
Keyword(s):  
Vortex Dynamics ◽  
Bluff Body ◽  
Turbulent Flame ◽  
Premixed Flames

scholarly journals Dynamics of lean premixed flames stabilized on a meso-scale bluff-body in an unconfined flow field

2018 ◽  
Vol 13 (6) ◽  
pp. 48 ◽  
Author(s):  
Yu Jeong Kim ◽  
Bok Jik Lee ◽  
Hong G. Im
Keyword(s):  
Bluff Body ◽  
Proper Time ◽  
Premixed Flames ◽  
Narrow Channel ◽  
Flame Stabilization ◽  
Inflow Velocity ◽  
Lean Premixed Flames ◽  
Lean Premixed ◽  
The Mean ◽  
Meso Scale

Two-dimensional direct numerical simulations were conducted to investigate the dynamics of lean premixed flames stabilized on a meso-scale bluff-body in hydrogen-air and syngas-air mixtures. To eliminate the flow confinement effect due to the narrow channel, a larger domain size at twenty times the bluff-body dimension was used in the new simulations. Flame/flow dynamics were examined as the mean inflow velocity is incrementally raised until blow-off occurs. As the mean inflow velocity is increased, several distinct modes in the flame shape and fluctuation patterns were observed. In contrast to our previous study with a narrow channel, the onset of local extinction was observed during the asymmetric vortex shedding mode. Consequently, the flame stabilization and blow-off behavior was found to be dictated by the combined effects of the hot product gas pocket entrained into the extinction zone and the ability to auto-ignite the mixture within the given residence time corresponding to the lateral flame fluctuations. A proper time scale analysis is attempted to characterize the flame blow-off mechanism, which turns out to be consistent with the classic theory of Zukoski and Marble.

The Effects of Fuel and Air Mixtures in Non-Premixed Combustion for a Bluff-Body Flame

2015 ◽  
Author(s):  
Lu Chen ◽  
Francine Battaglia
Keyword(s):  
Bluff Body ◽  
Numerical Study ◽  
Premixed Flames ◽  
Turbulence Models ◽  
Premixed Combustion ◽  
Oh Radicals ◽  
No Emission ◽  
Combustion Modeling ◽  
High Specific Heat ◽  
Low Levels

The bluff-body stabilized flame is used in a numerical study of the non-premixed flames. This paper shows numerical investigations on the effects of hydrogen compositions and nonflammable diluent mixtures on the combustion and NO emission characteristics of syngas non-premixed flames for a bluff-body burner. The assessment of turbulent non-premixed combustion modeling techniques is presented and discussed. The simulations study the predictive capabilities of five turbulence models and are compared with the experiments of Correa and Gulati [1] for a non-premixed flame of 27.5%CO/32.3%H2/40.2%N2 and air. The Realizable k-ε and the Reynolds Stress (RSM) models were found to perform the best. Based on this, a numerical study to assess the effects of hydrogen component on syngas non-premixed combustion was performed. As a result, hydrogen addition caused the radial velocity and strain rate to decrease, which was important for mixing to decrease NO. Also, the effectiveness of nonflammable diluent mixtures, including N2, CO2 and H2O, were characterized in terms of the ability to reduce NO emission in syngas non-premixed flames. Results indicated that CO2 was the most effective diluent to reduce NO emission and H2O was more effective than N2. CO2 diluent produced low levels of OH radical, which makes CO2 the most effective diluent. Although H2O increased OH radicals, it was still effective to decrease the thermal NO because of its high specific heat.

Blowoff mechanism of harmonically forced bluff body stabilized turbulent premixed flames

2012 ◽  
Vol 159 (2) ◽  
pp. 638-640 ◽  
Author(s):  
Swetaprovo Chaudhuri ◽  
Stanislav Kostka ◽  
Michael W. Renfro ◽  
Baki M. Cetegen
Keyword(s):  
Bluff Body ◽  
Premixed Flames ◽  
Turbulent Premixed Flames ◽  
Turbulent Premixed
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