Convective Ignition of Propellant Cylinders in a Developing Cross-Flow Field.
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 cal/cm2-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 m/s. test gases were 100%N2. 10%O2/90%N2 and 50%O2/50%N2. 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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1980
- Accession Number
- ADA091852
Entities
People
- Aviezer Birk
- Leonard H. Caveny
Organizations
- Princeton University