Laser absorption measurements of H2O and CO2 time-histories in cyclopropane/O2/argon mixtures at high temperature behind reflected shock waves

Abstract

As the simplest cycloalkane, cyclopropane is a highly strained three-membered ring hydrocarbon that exhibits high reactivity. In this work, H2O and CO2 time-histories for cyclopropane/O2/argon mixtures at high temperature have been measured behind reflected shock waves in a shock tube using laser absorption spectroscopy. Experiments were conducted at pressures around 2 atm, temperatures ranging from approximately 1500 to 1770 K, and equivalence ratios of 0.5, 1.0, and 2.0. H2O and CO2 were monitored using IR diode laser absorption at 2550.96 nm and 4191.51 nm, respectively, with a fixed-wavelength method. The measured H2O and CO2 time-histories provide new and stringent kinetic targets to validate and refine kinetic mechanisms for cyclopropane. The experimental results have been compared with the predictions of two recently developed combustion mechanisms to validate the performance of mechanisms. Rate-of-production and sensitivity analyses for the measured species have been carried out to identify the key reactions that affect the measured species profiles. Modifications to the rates of selected key reactions have been proposed, which can significantly improve the mechanism predictions. To the best of the authors’ knowledge, this study provides the first species time-history measurements in shock tubes for cyclopropane combustion.