OH Concentration and Burning Velocity in Counterflow Premixed Flames

Abstract

In this study, we have simulated counterflow premixed flames to discuss burning velocity and OH concentration. Two-types of flow configuration are considered. One is twin premixed flames in symmetric counterflow premixed mixtures. The other is a single-flame in counterflows consisted of premixed mixture and air. The fuel is propane, and the equivalence ratio is 0.7 to 1.0. The detailed chemical kinetics model of GRI-Mech 3.0 using 53 species and 325 reactions is adopted. To change the stretch rate, the inflow velocity is varied from 0.5 to 3.5 m/s. The distance between two inflow boundaries is 15 mm. Based on the reaction rate, we have estimated the burning velocity at different stretch rates. Results show that the burning velocity is decreased with an increase of stretch rate. The burning velocity of the single-flame is smaller than that of twin flames at the same equivalence ratio and stretch rate. The clear relationship between maximum OH concentration in the flame zone and burning velocity is observed especially in the case of single-flame.