[Using instantaneous spectra to determine dominant species in the DDT process of epoxypropane]

After solving problems of weak light detection, the calibration of the spectral sensitivity of the measuring system, and the synchronization of the measuring system, instantaneous emission spectra of epoxypropane in the process of deflagration to detonation transition (DDT) with the exposure time of 2-8 micros and the resolution of 0. 2 nm were acquired from six different side windows of an explosion shock tube. Using the corrected spectral data, curves of the optical radiant intensity of main reaction products versus the DDT distance from the ignition point were obtained. These curves provided information about the evolution of the reaction and the products during the DDT process. Results indicate that the chemical reaction rate of the gaseous fuel and the corresponding concentrations of intermediate products increased gradually at the deflagration stage, but at the moment of deflagration to detonation transition, the reaction rate increased rapidly and the concentrations! of products increased sharply. Among these main products, concentration increments of molecule CO, and radicals CHO and OH were greater than other products, which means that CO, CHO and OH are the dominant species that affect the DDT process greatly.