Accession Number:

AD0763515

Title:

Ignition of Aluminum Particle Streams,

Descriptive Note:

Corporate Author:

WATERLOO UNIV (ONTARIO) DEPT OF MECHANICAL ENGINEERING

Personal Author(s):

Report Date:

1972-08-17

Pagination or Media Count:

7.0

Abstract:

The ignition of aluminum particle streams was studied in a steady-flow experiment in which aluminum powder carried in oxygen was ignited by a propane-oxygen pilot flame. Two measured particle size distributions were used, with average diameters of 25 micrometers and 120 micrometers. Particle-to-gas weight fractions were in the range from 0.1 to 0.5. Ignition times were deduced from flame photographs and high-speed motion pictures were used to follow the ignition event. A simple thermal ignition model was used to predict particle ignition times. The model takes into account the radiation from the burning stream of particles to the unignited particle, as well as to the heating of this particle by a finite volume of hot gas. The measured ignition times were independent of metal concentration. The stream with 35 micrometers mean size ignited at 0.5 ms and the stream with 120 micrometers mean size at 1.1 ms after injection into the flame, both independent of the metal flow rate. Comparison with the predicted ignition times for the two particle-size distributions shows that the ignition of the smallest particles masks the ignition of the other particles in the stream. Author

Subject Categories:

  • Metallurgy and Metallography
  • Combustion and Ignition

Distribution Statement:

APPROVED FOR PUBLIC RELEASE