Speciation Measurements

The thermal decomposition and oxidation of fuels is brought about by thousands of elementary reactions that themselves produce a wide range of transient atomic or molecular species.

Tracking the evolution of these transient species and intermediates is key to the development of accurate chemical kinetic models for these fuels.

Combining laser absorption spectroscopy with shock tube experiments enables reliable, time-resolved, and quantitative measurement of radical and stable species in reacting systems.

By selecting suitable wavelengths targeting the species of interest, we have simultaneously measured the time-histories of six species at a time in a single shock tube experiment [1], as shown in the schematic above. This capability is unique to our lab and has enabled numerous fundamental chemical kinetic studies and the determination of rate constants of several key elementary reactions with extremely low uncertainty.

These rate constants form the backbone of modern detailed kinetic models that are being increasingly combined with computational fluid dynamics (CFD) codes to simulate engine and industrial operations over a wide range of conditions.

To learn more, check out some of our publications:

[1] S.J. Cassady, R. Choudhary, N.H. Pinkowski, J. Shao, D.F. Davidson, and R. K. Hanson, “The thermal decomposition of ethane,” Fuel, Vol. 268 (2020), p.117409. DOI: 10.1016/j.fuel.2020.117409

[2] R. Choudhary, V. Boddapati, S. Clees, J.J. Girard, Y. Peng, J. Shao, D.F. Davidson, and R.K. Hanson, “Shock tube study of ethanol pyrolysis I: Multi-species time-history measurements,” Combustion and Flame, Vol. 233 (2021), p.111553. DOI: 10.1016/j.combustflame.2021.111553