3.6. Correlation on the ignition delay time
Fig. 9 gives the measured ignition delay times of methane–air mixtures. Good linear dependence of logarithmic ignition delay times upon 1000/T BMS-538203 noted under different test conditions. Therefore, fitting correlations of ignition delay times as a function of p, ? and T for the methane–air mixture are correlated through regression as follows:equation(6)τ=1.09×10-3p-0.68?-0.04exp40.98±0.51kcal·mol-1RT,R2=0.983where τ is ignition delay time in μs, p is pressure in atm, ? is equivalence ratio, R = 1.986 × 10−3 kcal/(mol K) is the universal gas constant, and T is temperature in K. Eq. (6) gives good regression (R2 > 0.98) on the measured ignition delay times. Because of the experimental range of latitudinal gradient study, this correlation is applicable to the temperature range of 1300–1900 K, pressure range of 1.0–10 atm, equivalence ratio range of 0.5–2.0.