Lewis number effects on edge-flame propagation in lifted turbulent flames

Abstract

Three turbulent lifted slot-jet flames of different fuel Lewis numbers are studied using direct numerical simulation (DNS). To reduce the computational cost, a one-step chemistry model is employed with a mixture-fraction dependent activation energy reproducing the dependence of the laminar flame speed on the equivalence ratio which is representative of hydrocarbon fuels. In addition to turbulent flames, axisymmetric laminar jet flames with a same chemistry model to that of turbulent flames are simulated. It is found that the maximum reaction rate decreases as the Lewis number increases in the laminar cases. Analysis of the turbulent cases reveals that the extinction limit is affected by the ..