Suppression of Effectiveness Studies of Halon-Alternative Agents in a Detonation/Deflagration Tube
G. Gmurczyk, W L. Grosshandler
The paper constitutes a brief report on the research done under highly dynamic conditions to find alternatives to halon 1301 for application to aircraft in-flight fire protection. Experimental investigations of the effect of the presence of halon-alternative agents on the suppression of premixed high-speed turbulent flamedquasi-detonations have been carried out in a 7.5 m long, 50 mm diameter tube. Lean and stoichiometric C,H,/air mixtures in the absence of any halocarbon, initially at 100 kPa and 295 K, constitute the reference states. A primary objective of the work has been to determine the relative suppression effectiveness of different agents under highly dynamic situations, without the undue influence of either the ignition event or the mixing of the agent into the flame front. This was accomplished by generating a highly turbulent flamdquasi-detonation in the driver section, which contained no suppressant, followed by measurements of the velocity and pressure ratio as the shocWflame wave front entered the test section of the tube, which contained suppressant premixed with the same fuellair combination. A turbulence generator in the form of a spiral obstruction was used in the tube to broaden the gas dynamic conditions attainable by the flame. Flame and shock wave velocities up to 1300 m/s, pressure ratios across the shock fronts over 26: 1, and shock wave/flame spacings of the order of 10 cm were measured with piezo-electric pressure transducers and fast photodiodes. The experimental facility was successfully employed to clearly discriminate among the dynamic characteristics of the alternative compounds, revealing behavior distinct from what was observed in companion studies using atmospheric non-premixed flames. The suppression process is strongly influenced by the concentration of an agent, the structure and composition of an agent molecule, and the composition of the combustible mixture itself.
and Grosshandler, W.
Suppression of Effectiveness Studies of Halon-Alternative Agents in a Detonation/Deflagration Tube, Other, National Institute of Standards and Technology, Gaithersburg, MD, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=909901
(Accessed February 21, 2024)