Shock Tube Ignition Delay Measurements of Decalin/Air Mixtures at High Temperatures

Abstract

Ignition delay measurements of gas-phase decalin/air mixtures were performed in a shock tube at temperatures of 950-1395 K, pressures of 1.82×10 to 6.56×10 Pa, and equivalence ratios of 0.5, 1.0, and 2.0. The ignition delay time was determined using the reflected shock wave pressure and CH* emission monitored at the sidewall. The effects of temperature, pressure, and equivalence ratio on the ignition delay time of decalin were investigated systematically. The results show that increasing the temperature or pressure decreases the ignition delay time. Opposite ignition delay dependences on the equivalence ratio were observed for decalin/air at high and low pressures, for the first time. At 15.15×10 Pa, the fuel-rich mixture showed the shortest ignition delay time, and the fuel-lean mixture gave the longest one. However, at 2.02×10 Pa, the fuelrich mixture had the longest ignition delay time. Comparisons of the experimental data with predictions based on the available kinetic mechanism were made; the trends in the experimental data were in good agreement with the predictions under all conditions studied. A sensitivity analysis was performed to obtain insights into the effects of the equivalence ratio on the ignition delay time at low and high pressures. The results show that ignition is mainly controlled by the reaction H+O2=OH+O at 2.02×10 Pa. However, the reactions involving decalin and its corresponding radicals play important roles at 15.15×10 Pa. 836 HE Jiu-Ning et al.: Shock Tube Ignition Delay Measurements of Decalin/Air Mixtures at High Temperatures No.5