Impinging flame jets have been widely studied
because of their importance in a range of
applications such as materials processing and fire
safety. The purpose here was to determine the
importance of radiation, convection, and
thermochemical heat release (TCHR) under a range of
conditions. Natural gas was premixed with oxidants
ranging from air to pure oxygen in a round burner
that produced uniform exit conditions. Flames
impinged perpendicular to a water-cooled flat disk
segmented into 6 concentric calorimeteric sections
to measure radial heat flux distribution.
Many parameters were varied such as firing rate,
burner-to-disk spacing, oxidant composition and
disk surface treatment. Untreated, polished,
blackened, alumina-coated and platinum-coated disk
surfaces made of stainless steel, copper or brass
were tested. High (blackened) vs. low (polished)
emissivity surfaces showed nonluminous gaseous
radiation was less than 10% of the total heat flux.
Noncatalytic (alumina) vs. catalytic (platimum)
surfaces showed that TCHR was only important for
high O2 oxidants. The radial location of the highest
heat flux depended on oxidant composition.