Reduced Gravity Combustion of Propanol Droplets in Oxygen-Inert Environments

Abstract

Reduced gravity combustion experiments were performed with individual fiber-supported propanol droplets that were initially about 1 mm in diameter. The environment was composed of an oxygen-inert mixture. Helium, argon, xenon, nitrogen, and carbon dioxide were used as inerts, the oxygen mole fraction was 0.21, and the pressure was 0.03, 0.1, or 0.3 MPa. Use of helium caused extinction at 0.03 MPa and 0.1 MPa, but extinction was not observed in other oxygen-inert experiments within the 2.2 s reduced-gravity time available. Burning rates and sooting behaviors varied appreciably with the inert gas and the ambient pressure. Flame standoff ratios were generally quasisteady, and experimental flame standoff ratio data are compared with simplified theoretical predictions.

Keywords:

• liquid droplets
• microgravity flame phenomena

ACKNOWLEDGMENTS

This research was supported by the NASA Microgravity Combustion Program. The Technical Monitor was Dr. D. L. Dietrich. Gratitude is also expressed to E. Baumann, A. G. Birchenough, G. C. Blank, M. Camargo, L. A. Casco, D. L. Dietrich, C. Hampton, D. Kralj, M. McMillan, J. C. Owens, S. Rogers, L. Ross, and J. Wessel for their assistance at the NASA Glenn Research Center at Lewis Field.

Notes

Initial droplet diameters in mm are listed in parentheses.