Ethylene combustion studied over a wide temperature range in high-temperature shock waves

The initiation of ethylene combustion (at φ=1 and φ=1.5) was studied over a wide range of temperatures (∼800-1620 K) in shock waves. Ignition delay data showed the presence of two or three different chemically controlling regimes in the combustion. At low temperatures (∼900-1000 K) the time development of a combustion bubble was tracked via Schlieren techniques and was observed to grow slowly. Unburnt gas between the bubble and end wall that was compressed and heated by the latter exploded and gave rise to a strong combustion wave that traveled back through the partially burning gas. Emission measurements showed the presence of CH∗, OH∗, C 2 ∗, and a continuum emission attributed to CO 2 ∗ flame bands. C 2 ∗ was found to be only important in richer mixtures. CH∗ was formed only microseconds ahead of the other diatomics.