scholarly journals Analysis of direct numerical simulations of ignition fronts in turbulent non-premixed flames in the context of conditional moment closure

2007 ◽  
Vol 31 (1) ◽  
pp. 1683-1690 ◽  
Author(s):  
E.S. Richardson ◽  
N. Chakraborty ◽  
E. Mastorakos
Keyword(s):  
Numerical Simulations ◽  
Premixed Flames ◽  
Direct Numerical Simulations ◽  
Moment Closure ◽  
Conditional Moment ◽  
Conditional Moment Closure

Conditional Moment Closure for Turbulent Premixed Flames

2012 ◽  
Vol 184 (10-11) ◽  
pp. 1743-1767 ◽  
Author(s):  
S. Amzin ◽  
N. Swaminathan ◽  
J. W. Rogerson ◽  
J. H. Kent
Keyword(s):  
Premixed Flames ◽  
Moment Closure ◽  
Turbulent Premixed Flames ◽  
Conditional Moment ◽  
Conditional Moment Closure ◽  
Turbulent Premixed

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 Modelling of Conditional Scalar Dissipation Rate in Turbulent Premixed Combustion

Computation ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 26 ◽  
Author(s):  
Shokri Amzin ◽  
Mariusz Domagała
Keyword(s):  
Dissipation Rate ◽  
Premixed Flames ◽  
Moment Closure ◽  
Navier Stokes ◽  
Scalar Dissipation ◽  
Flame Surface ◽  
Scalar Dissipation Rate ◽  
Turbulent Premixed Flames ◽  
Conditional Moment ◽  
Turbulent Premixed

In turbulent premixed flames, for the mixing at a molecular level of reactants and products on the flame surface, it is crucial to sustain the combustion. This mixing phenomenon is featured by the scalar dissipation rate, which may be broadly defined as the rate of micro-mixing at small scales. This term, which appears in many turbulent combustion methods, includes the Conditional Moment Closure (CMC) and the Probability Density Function (PDF), requires an accurate model. In this study, a mathematical closure for the conditional mean scalar dissipation rate, <Nc|ζ>, in Reynolds, Averaged Navier–Stokes (RANS) context is proposed and tested against two different Direct Numerical Simulation (DNS) databases having different thermochemical and turbulence conditions. These databases consist of lean turbulent premixed V-flames of the CH4-air mixture and stoichiometric turbulent premixed flames of H2-air. The mathematical model has successfully predicted the peak and the typical profile of <Nc|ζ> with the sample space ζ and its prediction was consistent with an earlier study.

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