Characterization of aluminum at the surface of fine-AP/HTPB composite propellants

J. C. Mullen, M. Q. Brewster

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


Aluminum surface behavior-accumulation, agglomeration and ignition - is studied in a unique, wide-distribution ammonium perchlorate/hydroxyl-terminated polybutadiene (AP/HTPB) propellant formulation that results in low Al agglomeration, even at low pressures (1-30 atm). A fuel-rich binder matrix highly loaded with fine (2-μm) AP (FAP) at 75/25:FAP/binder is found to have premixed flame conditions that produce minimal agglomeration (without ignition) of 15-μm Al. Coarse AP (CAP) is added to the system in the form of either particles (200 or 400 μm) or pressed-AP laminates (simulated CAP). In the 2D laminate system the CAP/matrix flame structure is seen to be similar to that previously described for non-aluminized laminates with split (diffusion) and merged (premixed) flame regimes depending on pressure and fuel-matrix thickness. Both laminate and particulate systems show that with CAP present, Al can agglomerate more extensively on CAP via lateral surface migration from fuel matrix to the CAP region. The particulate CAP system also shows that Al can accumulate/agglomerate via settling on CAP from above (in the direction of burning). Both systems, but more clearly the 2-D laminates, show that with CAP present, Al is ignited by the outer CAP/matrix canopy flames. Thus a propellant formulation is proposed for reducing overall Al agglomeration through intrinsically reduced agglomeration in the fuel-matrix and a reduced number of CAP-particle agglomerates via higher FAP/CAP ratio.

Original languageEnglish (US)
Title of host publication44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
ISBN (Print)9781563479434
StatePublished - 2008

Publication series

Name44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit

ASJC Scopus subject areas

  • Aerospace Engineering
  • Control and Systems Engineering
  • Space and Planetary Science
  • Energy(all)
  • Electrical and Electronic Engineering
  • Mechanical Engineering


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