Laser-recoil response of AP-HTPB propellants (1-5 atm): Selective pyrolysis response

S. R. Hickman, M. Q. Brewster

Research output: Contribution to conferencePaper

Abstract

The combustion of HTPB propellants containing fine AP was investigated using laser-driven, combustion recoil at [l to 5 atm. At 1 atm, binder-rich (70 to 75% AP), monomodal fine-AP (2 to 50 μm) propellants exhibit a prominent secondary (non-QSHOD) laser-driven response peak at 100 to 300 Hz, with frequency varying inversely with AP size. Adding coarse AP (resulting in a wide, bimodal AP distribution) causes the secondary response to disappear at 1 atm. Raising the pressure to 2 atm causes the secondary response to reappear and increase in frequency to 600-800 Hz (2 μm AP). This oscillatory combustion behavior is attributed to time-varying selective or disproportionate pyrolysis of AP and HTPB, (unsteady accumulation and depletion of AP at the propellant surface) and the associated compositional (stoichiometric) fluctuations that occur in the fuel-rich, premixed gas phase reaction zone adjacent to the fine-AP/HTPB solid region. Low Peclet number appears to be a requirement of achieving this condition. Undriven combustion recoil and thermocouple measurements at 1 atm exhibited spontaneous combustion and gas phase temperature oscillations in the monomodal fine-AP propellants and corroborate the selective pyrolysis mechanistic interpretation of the externally excited (laser-driven) resonant response.

Original languageEnglish (US)
StatePublished - Jan 1 1999
Event37th Aerospace Sciences Meeting and Exhibit, 1999 - Reno, United States
Duration: Jan 11 1999Jan 14 1999

Other

Other37th Aerospace Sciences Meeting and Exhibit, 1999
CountryUnited States
CityReno
Period1/11/991/14/99

ASJC Scopus subject areas

  • Space and Planetary Science
  • Aerospace Engineering

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    Hickman, S. R., & Brewster, M. Q. (1999). Laser-recoil response of AP-HTPB propellants (1-5 atm): Selective pyrolysis response. Paper presented at 37th Aerospace Sciences Meeting and Exhibit, 1999, Reno, United States.