Experiments on Submillimeter Free Droplet Flame Extinction

Abstract

Flame extinction of n-heptane, n-decane, and n-hexadecane droplets freely falling through hot gases from a flat flame burner was investigated. Initial droplet diameters were in the range 270–285 µm. The hot gases from the flat flame burner were injected into straight and contoured flow tubes, providing flow environments that had various degrees of convection. Transport properties were modified through inert gas substitution as an efficient means of adjusting both quasisteady burning rates and extinction conditions to satisfy experimental constraints. The experiments suggest that within the uncertainty of the measurements, external convective flows do not significantly influence extinction diameters for the droplet Reynolds number range 0.01 ≤ Re ≤ 0.1.

Keywords:

• Droplet
• Microgravity

Notes

The O₂, CO₂, H₂O, and N₂ molar percentages, which are for the post-combustion gases from the flat-flame burner, were calculated assuming equilibrium.

*Tube configurations:.

C Contoured Tube Configuration.

S Straight Tube Configuration.

^#Droplet Extinction Criteria:.

1 Based upon disappearance of the flame.

2 Based upon a sudden change of the slope of the square of the droplet diameter vs. time.

The present affiliation for D. F. Wang is GE Energy, Atlanta, Georgia, USA.