Improving the Predictive Accuracy for Ketene in Diacetyl Laminar Premixed Flames: Experiment and Model Analysis

Ketene is an important species in core mechanisms for the combustion of hydrocarbon and oxygenated fuels, but direct experiments with ketene are challenging to conduct due to its high reactivity. Diacetyl can be used as a precursor of ketene, and abundant ketene is present in premixed flames of diacetyl. However, predictions of ketene in diacetyl flames with previous models have significant uncertainties. The study of Sun et al. [Sun, W.; Wang, J.; Huang, C.; Hansen, N.; Yang, B. Combust. Flame, 2019, 205, 11-21, DOI: 10.1016/j.combustflame.2019.03.037] shows that the flame structure measurements should be performed under certain conditions to improve the predictive accuracy of ketene in diacetyl flames. In this work, the structures of three laminar premixed flames of diacetyl under atmospheric pressure in a range of equivalence ratios are examined with flame-sampling molecular-beam mass spectrometry (MBMS). With the new experimental data and the data available in literature, Bayesian analysis is performed to optimize the kinetic model. The obtained optimized model is compared with the original one, and the results show that the optimized model agrees better with the experimental data than the original one. The uncertainties of the rate coefficients of some key reactions are constrained with these experimental data, which eventually leads to smaller modeling uncertainties for ketene concentrations under studied conditions.