Influence of ignition criterion and dilution gas on ignition delay of ethylene

Ignition delay of ethylene (C2H4) are measured under different temperatures in a rectangle shock tube to recognize the effects from diluent gases (nitrogen or argon) and criteria which is identified by pressure, bulk and radical chemiluminescences of OH and CH at specified wavelengths. Pressures were recorded by piezoelectric sensors (PCBs), and bulk chemiluminescence was detected by a photomultiplier (PMT) and an optical fiber. The chemiluminescences of OH and CH radicals were grated by spectrometer first, and then recorded by the PMT. The ignition delay is determined from the pressure and intensity histories of bulk and radical chemiluminescences at the points which share the same distances from the close end. Ignition delay database was built for mixture of C2H4/O2/N2 and C2H4/O2/Ar. Measurement and methodology are verified by the repeated experimental data under the same conditions. In the case of stoichimetric equivalence and pressure at 0.2 MPa, ignition delays were obtained and fitted with temperature as Arrhenius formula for mixtures of C2H4/O2/N2 and C2H4/O2/Ar at temperature ranging from 905 K to 1 489 K. Results show that the relative error of ignition delays is about 15%. Based on pressure, bulk and radical chemiluminescences, the relationships between the ignition delay and temperature remain the same although the ignition delay from single measurement is a bit different. Basically, the ignition delay of C2H4/O2/N2 is greater than that of C2H4/O2/Ar. The fitting relationship between ignition delay and temperature of C2H4/O2 /Ar in high temperature zone and low temperature zone is different, and the turning temperature is about 1 121 K. © 2020, Editorial Staff of EXPLOSION AND SHOCK WAVES. All right reserved.