Accession Number : ADA313427

Title :   High Pressure Boron Ignition and Combustion.

Descriptive Note : Final rept. 21 Jul 93-20 Jul 96,

Corporate Author : ILLINOIS UNIV AT URBANA DEPT OF AERONAUTICAL AND ASTRONAUTICAL ENGINEERING

Personal Author(s) : Burton, R. L. ; Krier, H.

PDF Url : ADA313427

Report Date : 01 SEP 1996

Pagination or Media Count : 49

Abstract : The high potential energy release of boron makes it a prime candidate for a high enthalpy fuel or as a fuel additive to solid propellant formulations, as well as a prospective additive for tailoring energy release rates of explosive grains. The problem of long ignition delays at atmospheric and lower pressures, caused by a combination of factors which include the necessity to remove a combustion-retarding oxide layer from the particles, a high vaporization temperature for the pure boron substrate, and slow condensation kinetics, have generally precluded the use of boron for energetic fuel applications at these pressures. This report summarizes experiments which measure an order of magnitude shorter ignition delays than previously published 1 atm data, for pure and reduced oxygen and oxygen mixtures with water vapor and fluorine compounds (H, HF) over 8.5 to 34 atm and 2000 to 3000 K. Ignition delays in the 300 to 500 microsecond range are observed in a shock tube, decreasing with increasing temperature, and increasing twofold when oxygen concentrations are reduced to 5% in Ar. Fluorine, from dissociated 1% SF6 in O2, is seen to decrease ignition delays by a factor of 1.7 compared to pure oxygen. A combustion chamber is used at a peak pressure of 157 atm and temperature in excess of 2800 K to study ignition delays at higher pressures than are possible in the shock tube. Endwall emission spectra of BO2 are recorded for comparison with boron ignition models.

Descriptors :   *HIGH PRESSURE, *EXPLOSIVES, *OXYGEN, *COMBUSTION, *DELAY, *IGNITION, *BORON COMPOUNDS, HIGH TEMPERATURE, EMISSION SPECTRA, LOW PRESSURE, SUBSTRATES, ENERGY TRANSFER, MIXTURES, HIGH ENERGY, PARTICLES, KINETICS, POTENTIAL ENERGY, ENERGETIC PROPERTIES, ENTHALPY, CONCENTRATION(CHEMISTRY), WATER VAPOR, CONDENSATION, SHOCK TUBES, FLUORINE COMPOUNDS, FORMULATIONS(CHEMISTRY), SOLID PROPELLANTS, FUEL ADDITIVES.

Subject Categories : Electric and Ion Propulsion
      Inorganic Chemistry
      Ammunition and Explosives

Distribution Statement : APPROVED FOR PUBLIC RELEASE