BURNING AND SOOTING BEHAVIOR OF ETHANOL DROPLET COMBUSTION UNDER MICROGRAVITY CONDITIONS

Abstract

In an effort to gain a better understanding of the burning and sooting behavior of ethanol, isolated droplet combustion experiments were performed in the 2.2-s drop tower at NASA Glenn Research Center. The measurement of the burning rate, soot standoff ratio, and soot volume fraction are described in which initial droplet diameter, oxygen concentration, and ambient pressure were varied. The experiments reveal that while ethanol droplets burn in 1-atm air without soot formation, luminous radiation from soot particles is observed at higher pressures, with increased sooting at higher oxygen volume fraction. Increases in the oxygen concentration at elevated pressures results in a nonmonotonic behavior in the measured soot volume fraction. These experiments provide the first quantitative measurements of the soot volume fraction for ethanol droplet burning under microgravity conditions.

Keywords:

• ethanol
• droplet combustion
• soot
• microgravity

We gratefully acknowledge the insights and helpful discussions provided by Dr. Paul Ferkul of the NASA Glenn Research Center (GRC). Support from NASA through Grant NCC3-822 is gratefully acknowledged. The support of the NASA GRC staff is sincerely appreciated.