Transient Emission Spectra from OH, CH and C2 Free Radicals in the Combustion Reaction of n-Decane
WANG Li-dong1, LI Ping1*, ZHANG Chang-hua1, TANG Hong-chang1, YE Bin1, LI Xiang-yuan2
1. Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China 2. College of Chemical Engineering, Sichuan University, Chengdu 610065, China
Abstract：Using an intensified spectroscopic detector CCD and a heated shock tube, transient emission spectra of n-decane in the combustion reaction were measured in a spectral range of 200~850 nm. Experiments were conducted at temperatures of 1 100~1 600 K, a pressure of 2.0 atm, an initial fuel mole fraction of 1.0% and an equivalence ratio of 1.0. Results show that the main emission bands are attributed to OH, CH and C2 radicals produced during the combustion process of n-decane. Emission intensities of the three radicals reached their maximums only after 5 μs from the onset of their ignitions. After about 30 μs had passed, the band of OH radical was still observed, but the bands of CH and C2 radicals almost disappeared. Time histories of spectral emission intensities represent the time histories of concentrations of the three radicals during the process of combustion. The emission peak ratio of OH(306.4 nm)/CH(431.4 nm) is approximately 27/100 in the combustion of n-decane, which is much greater than the corresponding ratio of about 7/100 in the combustion of n-heptane. This result reveals that the two fuels have different reaction mechanisms. High resolution characteristic spectra of CH and C2 were also acquired in the present experiment, the spectra show the rotational structures of the bands clearly. Current results are valuable for understanding the property and validating the mechanism of n-decane combustion reaction.
[1] Jahangirian S, Dooley S, Haas F M, et al. Combustion and Flame, 2012, 159(1): 30. [2] Zhukov V P, Sechenov V A, Starikovskii A Y. Combustion and Flame, 2008, 153(1-2): 130. [3] Olchanski E, Burcat A. International Journal of Chemical Kinetics, 2006, 38(12): 703. [4] Bikasa G, Peters N. Combustion and Flame, 2001, 126(1-2): 1456. [5] Titova N S, Torokhov S A, Starik A M. Combustion, Explosion, and Shock Wave, 2011, 47(2): 129. [6] Westbrook C K, Pitz W J, Herbinet O, et al. Combustion and Flame, 2009, 156(1): 181. [7] Zhukov V P. Combustion and Flame, 2009, 156(8):1674.
