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Journal of Combustion
Volume 2013, Article ID 154202, 6 pages
Research Article

Combustion of Submillimeter Heptane/Methanol and Heptane/Ethanol Droplets in Reduced Gravity

1Mechanical and Aerospace Engineering Department, University of California, Davis, CA 95616, USA
2Rafael, Haifa 31021, Israel
3Tesla Motors, 3500 Deer Creek Road, Palo Alto, CA 94304, USA

Received 29 September 2012; Revised 8 January 2013; Accepted 8 January 2013

Academic Editor: Constantine D. Rakopoulos

Copyright © 2013 I. Aharon et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Reduced-gravity experiments were performed on combustion of droplets composed of n-heptane mixed with methanol or ethanol. The initial alcohol mass fraction in a droplet was 0% (pure heptane) or 5%. The experiments were performed at 0.1 MPa and 25°C with air or with ambients of oxygen and helium with oxygen mole fractions of 0.3 or 0.4. Initial droplet diameters were in the range 0.67 mm to 0.92 mm. After considering measurement uncertainties, burning rates decreased appreciably as the initial droplet diameter increased for combustion in air but not for combustion in the oxygen/helium environments. It was also found that addition of either methanol or ethanol did not influence burning rates appreciably and that burning rates were larger for the oxygen/helium environments than for air if initial droplet diameter dependences were accounted for.