title: [Research on the Time-Histories of Exited Radicals during the Combustion of Methylcyclohexane by Emission Spectroscopy].
abstract: By using three monochromator! detecting systems, the light emissions of excited-state OH*, CH* and C* radicals during the transient combustion of methylcyclohexane at high temperatures behind the reflected shock wave have been measured. The dependence of the time-history and the relative intensity of excited radicals on the temperature have been obtained. The reflected shock temperatures are 1 200-1 700 K, the shock pressure is 1.5 atm, the mole fraction of methylcyclohexane is 0.1% and the equivalence ratio is 1.0. At the beginning of the combustion process, these three radicals were produced at the same time. The durations of these radicals became shorter when the temperature increases. At the same ignition temperature, the durations of CH* and OH* are longer than that of C2*. The C2* signal disappears below 1 400 K. The emission intensities of OH* and CH* are not sensitive to the temperature at T < 1 400 K. However, at high temperature (T > 1 400 K), the peak intensity of CH* increases rapidly as temperature increases, while C2* and OH* increase slowly. Current results were compared to the simulation results of corresponding chemical reaction mechanism. The obtained time-history of OH* radical matches well with the prediction of mechanism at low temperatures, but shows difference at high temperatures. The time-history of CH* radical matches well between experimental and simulated results at high temperatures, however, the simulated durations of CH* are longer than the experimental results at low temperatures. Current work provides experimental data to validate and optimize corresponding chemical reaction mechanism containing excited-state species.
authors.forename: You-liang
authors.initials: YL
authors.lastname: Li
authors.forename: Jiu-ning
authors.initials: JN
authors.lastname: He
authors.lastname: Zhang Chang-hua
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Xiang-yuan
authors.initials: XY
authors.lastname: Li