AP/HTPB laminate propellant flame structure: Fuel-lean intrinsic instability

R. P. Fitzgerald, M. Q. Brewster

Research output: Contribution to journalConference articlepeer-review


Two-dimensional laminate propellant flames of ammonium Perchlorate (AP) and hydroxyl-terminated polybutadiene (HTPB) have been observed using infrared (IR) and ultraviolet (UV) emission and transmission imaging. Under fuel-lean conditions and at slightly elevated pressures (4 atm), intrinsic instability has been observed in the form of a leading-edge flame kernel whose location oscillates laterally about the central fuel binder layer. A mechanistic explanation for this behavior is described in terms of local gas-phase equivalence ratio, surface geometry, and gas-solid thermal coupling. The flame structure under these conditions is unique in having a leading-edge flame kernel that appears to be more spatially distinct from the trailing diffusion flame than under nonoscillatory conditions. Other results are reported, including gas-phase rotational and vibrational temperature estimates based on HCl emission imaging spectroscopy. These results add to a growing set of flame and burning surface observations being assembled for the purpose of comprehensive validation of multi-dimensional AP composite propellant computational combustion models.

Original languageEnglish (US)
Pages (from-to)2071-2078
Number of pages8
JournalProceedings of the Combustion Institute
Volume31 II
Issue number2
StatePublished - Jan 1 2007
Event31st International Symposium on Combustion - Heidelberg, Germany
Duration: Aug 5 2006Aug 11 2006


  • Diffusion flames
  • Flame instability
  • Heterogeneous propellants
  • IR spectroscopy

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

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