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Published 2013 | public
Journal Article

Dynamics of excited hydroxyl radicals in hydrogen-based mixtures behind reflected shock waves


The chemiluminescence originating from OH∗, the excited hydroxyl radical, is one of the most extensively used diagnostics to characterize auto-ignition delay time of gaseous mixtures behind reflected shock waves. We have carried out new experiments and modeling of this diagnostic as well as analyzed previous results for hydrogen-based mixtures, including H_2–O_2, H_2O_2–H_(2)O, H_2–N_(2)O and H_2–O_2–N_(2)O. The experiments were analyzed with a detailed chemical reaction model which included mechanisms for OH∗ creation, quenching and emission. Simulations of the reaction behind reflected shock waves were used to predict OH∗ emission profiles and compare this with measured results as well as profiles of temperature and the ground state concentrations of OH. Analysis of OH∗ rates of progress demonstrates that a quasi-steady state approximation is applicable and an algebraic model for OH∗ concentrations can be derived that relates emission to the product of concentrations of O and H for H_2–O_2 and H_(2)O_2 mixtures and an additional contribution by the product of H and N_(2)O when N_(2)O is an oxidizer.

Additional Information

© 2012 The Combustion Institute. Published by Elsevier Inc. Available online 21 July 2012. The authors acknowledge Aurélien Demenay, Université d'Orléans, and Jason Damazo, Caltech, for their help in setting-up the shock-tube at the Explosion Dynamics Laboratory at Caltech.

Additional details

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October 23, 2023