NASA Logo, External Link
Facebook icon, External Link to NASA STI page on Facebook Twitter icon, External Link to NASA STI on Twitter YouTube icon, External Link to NASA STI Channel on YouTube RSS icon, External Link to New NASA STI RSS Feed AddThis share icon
 

Record Details

Record 2 of 119
Stationary premixed flames in spherical and cylindrical geometries
Author and Affiliation:
Ronney, P. D.(University of Southern California, Los Angeles, CA, United States)
Whaling, K. N.(Princeton University, Princeton, NJ, United States)
Abbud-Madrid, A.(Princeton University, Princeton, NJ, United States)
Gatto, J. L.(Princeton University, Princeton, NJ, United States)
Pisowiscz, V. L.(Princeton University, Princeton, NJ, United States)
Abstract: Stationary source-free spherical flames ('flame balls') in premixed combustible gases were studied by employing low-gravity (micro-g) environments in a drop tower and an aircraft flying parabolic trajectories to diminish the impact of buoyancy-induced convective flow. Flame balls were found in all mixture families tested when: (1) the Lewis number Le of the deficient reactant was sufficiently low; and (2) the compositions were sufficiently close to the flammability limits. Probably as a consequence of the reduction in buoyant convection, the flammability limits at micro-g were significantly more dilute than those at Earth gravity; for example, 3.35% H2 vs 4.0% H2 in lean H2-air mixtures. By comparison with analytical and computational models, it is inferred that the phenomenon is probably related to diffusive-thermal effects in low-Le mixtures in conjunction with flame-front curvature and radiative heat losses from the combustion products. The chemical reaction mechanism appears to play no qualitative role. In the aircraft experiments, the gravity levels (approximately equal 10(exp -2)g(sub 0)) were found to cause noticeable motion of flame balls due to buoyancy, which in turn influenced the behavior of flame balls. At these g levels, a new type of transient, nearly cylindrical flame structure, termed 'flame strings,' was observed.
Publication Date: Mar 01, 1994
Document ID:
19950054566
(Acquired Dec 28, 1995)
Accession Number: 95A86165
Subject Category: PROPELLANTS AND FUELS
Document Type: Journal Article
Publication Information: AIAA Journal (ISSN 0001-1452); 32; 3; p. 569-577
Publisher Information: United States
Contract/Grant/Task Num: NAG3-965; NAG3-1242; NAG3-1523
Financial Sponsor: NASA; United States
Organization Source: NASA Lewis Research Center; Cleveland, OH, United States
Description: 9p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: AIR; BUOYANCY; CARBON DIOXIDE; FLAME PROPAGATION; FLAMMABLE GASES; HYDROGEN; METHANE; MICROGRAVITY; PREMIXED FLAMES; SULFUR HEXAFLUORIDE; C-135 AIRCRAFT; CAMERAS; CONVECTIVE FLOW; DROP TOWERS; FLAMMABILITY; LEWIS NUMBERS; PARABOLIC FLIGHT; RADIATIVE HEAT TRANSFER
Imprint And Other Notes: AIAA Journal vol. 32, no. 3 p. 569-577 March 1994
Availability Source: Other Sources
› Back to Top
Find Similar Records
NASA Logo, External Link
NASA Official: Gerald Steeman
Site Curator: STI Program
Last Modified: August 19, 2011
Contact Us