Chemically-passive suppression of laminar premixed hydrogen flames in microgravity

Li Qiao, Yongxian Gu, Werner J.A. Dahm, Gerard M. Faeth, Elaine S. Oran

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Effects of chemically-passive Tire suppressants on laminar premixed hydrogen flames were investigated by combined use of microgravity experiments and computations. The experiments used a short-drop free-fall laboratory facility that provides at least 450 ms of 10-2 g. Near-limit laminar burning velocities were measured for outwardly propagating spherical stoichiometric hydrogen-air flames with varying concentrations of He, Ar, N 2 and CO2 as suppressants. Burning velocities were also computed using the steady, one-dimensional laminar premixed flame code PREMIX. Both measured and computed results showed the suppressants to increase in effectiveness in the order He, Ar, N2 to CO2. The differences in effectiveness are shown to result from increased quenching of reactions by the increased specific heat due to the suppressant and from changes in the transport rates near the flame. The addition of suppressant generally decreased Markstein numbers, which made the flames more susceptible to preferential-diffusion instability. This effect increases flame speeds and tends to counteract the effect of suppressant to reduce laminar burning velocities. The concentration needed for each suppressant to prevent flame propagation was also determined. Far from this flammability limit, agreement between measured and computed laminar burning velocities was good, but for near-limit flames the computed velocities were significantly lower than measured values. These near-limit differences may be due to third-body recombination rates for H+O 2+M=HO2+M reactions, and in particular to the third-body chaperon efficacy of various species M.

Original languageEnglish (US)
Title of host publicationCollection of Technical Papers - 44th AIAA Aerospace Sciences Meeting
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
Number of pages15
ISBN (Print)1563478072, 9781563478079
StatePublished - 2006
Externally publishedYes
Event44th AIAA Aerospace Sciences Meeting 2006 - Reno, NV, United States
Duration: Jan 9 2006Jan 12 2006

Publication series

NameCollection of Technical Papers - 44th AIAA Aerospace Sciences Meeting


Other44th AIAA Aerospace Sciences Meeting 2006
Country/TerritoryUnited States
CityReno, NV

ASJC Scopus subject areas

  • Space and Planetary Science
  • Aerospace Engineering


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