ID#: 225
Abstract Title: Ethylene Combustion Studied Over a Wide Temperature Range in High Temperature Shock Waves
Session Title: Shock Ignition
Session Date: 7/31/01
Session Start Time: 11:20 AM
Contributing Author: Cadman, P.
Organization: University of Wales
Country: U.K.
Authors: P. Cadman, J. Bambrey, G.O. Thomas , S.K. Box
Short Abstract: The initiation of ethylene combustion (at 0 = 1 and 1.5) was studied over a wide range of temperatures (800-2273K) in shock waves. Ignition delay data showed the presence of 2 or 3 different chemically controlling regimes in the combustion. Figure 1 shows the temperature dependence of the ignition delays of ethylene in N2/O2 mixtures. These were done on two different shock tubes under different conditions with a large amount of fuel (75 and 50% N2 , O2 and fuel making up the _ = 1 and 1.5). At low temperatures (T~900-1000K) the time development of a combustion bubble was tracked via Schlieren techniques and was seen to grow slowly. It was formed away from the backwall of the shock tube at the lower temperatures, a result which was unexpected. Unburnt gas, between the bubble and endwall which was compressed and heated by the latter, exploded and gave rise to a strong combustion wave which travelled back through the partially burning gas. Emission measurements showed the presence of CH*, OH*, C2* and a continuum emission attributed to CO2 * flame bands. C2* was found to be only important in richer mixtures. CH* was formed only ~µsecs ahead of the other diatomics. The spectra of CH* C2* and OH * was tracked from the initial developing combustion bubble. Further work and results on this system will be presented.