Stability characteristics of non-premixed turbulent jet flames of hydrogen and syngas blends with coaxial air

► Detachment stability of H2/CO syngas non-premixed jet flames is investigated. ► Critical fuel velocity decreases with increasing CO for single jet flame. ► Non-monotonic (ascending/descending) trends are observed in the velocity domain. ► Ascending/descending branches are understood by OH∗ chemiluminescence imaging. ► Ascending trends for all cases are collapsed in a single line in mass flux domain.