Radiative effects in space-based methanol/water droplet combustion experiments

A comprehensive mechanism for methanol oxidation

“…In addition, detailed liquid transport [68], chemiluminescent flame emission [69], and spectral radiative transport effects [71] have been investigated using methanol droplet combustion. Transient droplet burning rate, flame stand-off, and droplet burning extinction phenomena compare favorably with microgravity experiments performed using unsupported droplets [71] in ground-based droptower facilities and with fiber supported droplet experiments performed in a glovebox experiment aboard the Space Shuttle [72]. The reader is referred to these publications for detailed results and discussions regarding calculated flame structure and chemical aspects of droplet diffusion flames employing the present mechanism.…”

Comprehensive study of initial diameter effects and other observations on convection-free droplet combustion in the standard atmosphere for n-heptane, n-octane, and n-decane

“…For large D o where radiative losses from the flame to the ambience are more important than diffusive transport (regime III) an energy balance (discussed in Appendix A ) on the flame leads to an inverse power relationship, K ∝ D −n o ( n = 2/7 from the scaling analysis). Effects such as radiative extinction [9,25,26,36] and LTC phenomena as first postulated by Nayagam et al . in 2015 [37] and subsequently analyzed with detailed numerical modeling [38][39][40][41] may also be important in this regime.…”

“…Though the burning rate is predicted to be constant and independent of time and droplet size, experiments show that the burning rate decreases as the initial droplet diameter increases and that it depends on time [3,13,14,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] . This trend has not been fully explained, owing in part to the inability to model all of the important processes in droplet burning (i.e., unsteady transport, variable properties, soot formation, radiation, complex combustion chemistry).…”

Effects of Carbon Dioxide on Unsteady Combustion of Isolated Fuel Droplet in Microgravity

“…Researches measuring characteristic parameters of droplet combustion such as burning rate constant and flame standoff ratio have been widely conducted and a large part of their analysis have been based on classical d 2 -law 1,2) . However, experimental results show that the actual characteristic parameters of the droplet burning deviates from those under quasi-steady assumption [3][4][5] . Experimental evidence shows that the burning rate constant decreases as the initial droplet diameter increases and the flame standoff ratio increases as the droplet diameter decreases with time in microgravity 3,6,7) .…”