Numerical study of the effects of gravity on soot formation in laminar coflow methane/air diffusion flames under different air stream velocities

Fire safety in space – Investigating flame spread interaction over wires

“…In a similar manner, the interaction among spreading flames has been the subject of several studies [13,14] but still merits further scientific investigation, in particular, for microgravity and low characteristic forced velocities conditions. The absence of natural convection allows a significant increase of the time scales associated with transport and combustion processes, increasing both soot concentration [15] and radiative emissions, especially from the soot continuum [16]. Transport thus changes the nature of the combustion processes and the interaction between the flame and the solid fuels in a manner that is still not fully understood.…”

Effects of Gravity on Soot Formation in a Coflow Laminar Methane/Air Diffusion Flame

“…At low coflow air velocity the Fig. 4 Comparison of predicted soot volume fraction distributions under different gravity level with the peak values indicated flame height in microgravity is obviously taller than that at normal gravity (Kong and Liu 2009). This is in qualitative agreement with the experimental results that the observed microgravity flames are taller than their normal gravity counterparts (Bahadori et al 1990) where the fuel jet is issued into a quiescence environment.…”

“…Uniform inlet temperatures were assumed for both the fuel and the air streams: T F = 300 K, T A = 300 K. Uniform inlet coflow air velocity was assigned at ν A = 77.6 cm/s. The influences of the coflow air velocities on the flame structure and soot formation at different levels of gravity was discussed in another paper (Kong and Liu 2009), where three coflow air velocities of 77.6, 30, and 5 cm/s were investigated. The results showed that the coflow air velocity had significant effects on the flame structure and soot formation.…”

Proceeding of the 6th International Symposium on Radiative Transfer

“…It is noticed that the flame investigated by Kong and Liu is relatively large, being about 9 cm tall at microgravity. The importance of radiation absorption in microgravity flames, however, was not investigated in the study of Kong and Liu [10].…”

“…Although the enhanced importance of radiation heat loss in microgravity has been recognized [9], adequate quantitative understanding of the effects of thermal radiation transfer on laminar coflow diffusion flames is still lacking. A very recent numerical study by Kong and Liu [10] demonstrated that radiation transfer in microgravity laminar coflow methane/air diffusion flame can be so important that the flame temperature is lowered by more than 800 K due to radiation heat loss and the flame experiences partial extinction in the centerline region under certain conditions of their study. It is noticed that the flame investigated by Kong and Liu is relatively large, being about 9 cm tall at microgravity.…”