Studies on the outwardly and inwardly propagating spherical flames with radiative heat loss

Outwardly propagating spherical flame (OPF) and inwardly propagating spherical flame (IPF) with radiative heat loss have been investigated with emphasis placed on studying the effects of radiative heat loss and preferential diffusion on the flammability limit, flame propagating speed, and Markstein length of propagating spherical flame. The flame propagating speed for OPF and IPF at different Lewis numbers is found to change in opposite trends. The flammability region is shown to be extended/reduced for OPF with small/large Lewis number and IPF with large/small Lewis number. Furthermore, it is found that the Markstein length is strongly affected by radiative heat loss and the thermal-diffusion instability is enhanced by radiation for mixture with small Lewis number.