Flame structure in aluminized wide-distribution AP composite propellants

M Quinn Brewster, J. C. Mullen

Research output: Contribution to journalArticle

Abstract

Flame structure in wide-distribution ammonium-perchlorate (AP), hydroxyl-terminated-polybutadiene (HTPB) binder, aluminum (Al) composite propellants is studied using 2-D laminates with oxygenated binder. Very fine (2-μm) AP (FAP) is used to produce fuel-rich, matrix propellant (oxygenated binder) with a FAP/binder ratio of 75/25. Coarse AP (CAP) is simulated by pressed AP lamina. A flame-structure regime map for the CAP/oxy-fuel matrix interaction flame is generated as a function of oxy-fuel matrix thickness and pressure using high-speed video imaging analysis. The flame structure is found to be similar to that previously described using UV and IR imaging for non-aluminized laminates with split (diffusion) flame structure at high pressures (P) and low fuel thicknesses (L) and merged (partially premixed) flame structure for low P and L. The CAP/matrix flame regime boundary is shown to be correlated by Peclet number, indicating the relevance of conserved-scalar (Shvab-Zeldovich) theory with simple, global AP/hydrocarbon chemistry to describe the CAP/matrix diffusion-flame stoichiometry. Other findings include a slight stabilizing effect of Al on the 1-D premixed combustion of the marginally stable fuel-rich matrix. Also, when burning in 2-D laminates assisted slightly by the CAP/matrix interaction flame, the 75/25 matrix is found to burn flat (perpendicular to regression direction) even in the split-flame regime, in contrast to lower FAP/binder ratio matrices, which protrude into the gas-phase. Findings such as these are essential for developing a fundamental understanding of and truly predictive simulation capability for combustion of wide-distribution AP propellants, including plateau, mesa and bi-plateau propellants.

Original languageEnglish (US)
Pages (from-to)2340-2347
Number of pages8
JournalCombustion and Flame
Volume157
Issue number12
DOIs
StatePublished - Dec 1 2010

Keywords

  • Flame structure
  • Solid propellant

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Physics and Astronomy(all)

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