Flame-controlling continuation method for extinction of counterflow sooting flames with detailed chemistry

Abstract

The generation of S-curves for the extinction of counterflow sooting flames has been accomplished by implementing a flame-controlling continuation method inclusive of soot model. The code can generate solutions for augmented flamelets databases, including soot scalars, useful for Flamelet Progress Variable (FPV) tabulations for sooting turbulent simulations. Indeed, the inclusion of all S-curve's branches brings substantial improvements in the reproduction of extinction/re-ignition regimes or flame/acoustic interactions. In this context, developing a reliable tool for S-curve generation, with coupled reproduction of gas-phase and soot characteristics, is of great importance. The algorithm calculates the flamelet states through a 2-point flame-controlling continuation method with control on species mass fractions. Soot calculation is coupled with gas kinetics at every continuation so that flamelet states are inclusive of soot formation effects on precursors' consumption and flame temperature. The flame and soot features can be correctly predicted along the whole curve with smooth transitions between branches. A brief introduction on general S-curve properties is given, using the implementation on hydrogen flames with different oxidizer's inlet temperatures. Besides, soot characteristics are thoroughly investigated on ethylene flames at different pressures.