Accession Number:

ADA091852

Title:

Convective Ignition of Propellant Cylinders in a Developing Cross-Flow Field.

Descriptive Note:

Final rept. Oct 75-Aug 80,

Corporate Author:

PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENGINEERING

Personal Author(s):

Report Date:

1980-09-01

Pagination or Media Count:

194.0

Abstract:

The sensitivities of ignition delay time and site to the ambient conditions i.e., flow velocity, pressure, temperature and gas composition were investigated under high heat flux conditions e.g., 100 calcm2-s. A shock tunnel was used to provide up to 20 ms of flowing heated gas at 1 to 22 mpa, 1800 to 2300 k, 5 to 300 ms. test gases were 100N2. 10O290N2 and 50O250N2. Instrumentation included radiation detectors, high-speed shadowgraph sequences, pressure probes and heat flux gauges. Most of the tests were conducted with nitrocellulose-based propellants. The effect of high heating rates accompanying the initial flow transients and boundary layer development were very prominent in producing sub-millisecond ignition delays for oxygen-containing flows. Indeed, during their brief period on the order of 0.2 ms the heat fluxes are 4 to 5 times higher than corresponding well developed flow values. Flame blow-off occurred for high Reynolds numbers e.g., 16,000, low free stream oxygen content flows. Depending on the flow conditions first ignition occurred distinctly at the leading edge, trailing edge or at the flow separation region. Compared to triple-based propellant, single-based and double-based propellants ignited more rapidly in oxygen-containing flows. The experimental results indicate clearly that for the range of ambient conditions tested, the ignition is a gas phase process. The ignition processes in nonsteady reactive boundary layer flows were analyzed for the front stagnation flow region. The solution includes the boundary layer development and the transition and quasi-steady burning. Author

Subject Categories:

  • Ammunition and Explosives
  • Combustion and Ignition

Distribution Statement:

APPROVED FOR PUBLIC RELEASE