An improved approach to predict thermal NO from jet flames in multiple regimes

Researchers : Junghun Oh, Minsung Park, Daehyun Han

Importance of NOx prediction

    •Environmental issues have arisen, which motivates reducing NOx emission

    •Accurate prediction of NOx emission is necessary

 Main mechanisms of NO formation

Fenimore mechanism (prompt NO)

             - Fast time scale & Flame front

Zel’dovich mechanism (thermal NO)

             - Slow time scale & Post-flame region 

Different types of turbulent flames

• Premixed flame (TSF-Ar) 

• Nonpremixed flame (DLR-A)

• Partially premixed flame (Darmstadt flame)   

Laminar premixed, non-premixed and partially premixed triple flame simulations are performed to analyze flame characteristic

    • Comparison of NO source terms between DNS data and look-up from different tables

Multiple regimes in partially premixed flame were identified

    •  Primary reactions which occurs in lean premixed zone :

            O2+H+M⟺HO2+M

            HO2+OH⟺H2O+O2

    •  Black line denotes H2O and red-colored zone in left-side of contours presents high temperatures (over                       2000K)

Regime indicator by Knudsen (2012) is regarded to distinguish which regime is present at a particular mesh cell and particular point in time.

A need of modeling NO source using NOMANI model is confirmed

    •    To predict thermal NO better when we consider existing multi-regime models are based on flamelet-progress variable approach