Diagnosis of iso-octane combustion in a shock tube by emission spectroscopy

Ultraviolet–Visible emission from iso-octane combustion was measured behind reflected shock waves. OH∗, CH∗ and C2∗ were recorded as the major intermediate species. When the equivalence ratio increases, the emission intensity ratio of OH∗/CH∗ decreases and that of C2∗/OH∗ increases. Rotational and vibrational temperatures were determined by comparing the measured emission spectra with the simulated ones of CH∗ and C2∗. The rotational temperatures are in good agreement with the calculated adiabatic flame temperatures and the vibrational temperatures are significantly higher. Furthermore, ignition delay times were obtained to provide a database for the validation of the kinetic mechanism.