Ignition and Combustion of Energetic Particles at Ultra-high Pressures and Heating Rates

Open Access
Author:
Lee, Garrett Powell
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
August 15, 2012
Committee Members:
  • Kenneth K Kuo, Thesis Advisor
  • Laura Pauley, Thesis Advisor
  • Karen Ann Thole, Thesis Advisor
Keywords:
  • aluminum combustion
  • nickel coating
  • ballistic compressor
  • particle ignition
  • thermobaric weapon modeling
Abstract:
Aluminum combustion research is a field of great interest currently, and has been for quite some time. To date, however, all research into the field of aluminum combustion has taken place at relatively low pressures, either near atmospheric or pressures found in rocketry environments, which are orders of magnitude less than the pressures to be found in a post-detonation environment such as with thermobaric weaponry. To address this lack of data, a ballistic compressor was modified to produce peak pressures of 100,000 psi and maximum heating rates exceeding 106 K/sec to simulate a post-detonation environment. A series of tests was run with 9 and 32 μm Al particles, both with and without a nickel coating. The two sizes of particles were chosen to explore the effect of diffusion versus kinetically controlled combustion at high pressures. Previous research indicated that a nickel coating on aluminum particles lowered the ignition temperature, and the Ni-coated particles were to determine if this held true at higher pressures. These tests were run at peak test pressures of 20,000, 40,000, and 60,000 psi. The results of the testing regimen demonstrated that the nickel coating did indeed lower ignition delay when compared with the uncoated particles, and overall had higher observed intensities. The 9 μm particles also had a substantially shorter ignition delay than their 32 μm counterparts. The 20,000 psi experiments produced notably lower observed light intensities in the 32 μm uncoated particles than the 40,000 psi tests, indicating that many more particles were burning at the higher pressures. The fact that the Ni-coated 32 μm particles had high observed light intensity values in both the 20 and 40,000 psi tests indicates that the nickel coated particles can burn at much lower pressures. Unfortunately, the 60,000 psi tests produced inconclusive results due to damage to the sapphire viewing windows.