Where [O2] denotes molar concentration of oxygen and A, B and C means constants. The ignition delay, 7τ, is calculated so that it satisfies the integral of Eq.(1). The temperature of gas, T, was estimated from the pressure measured in the cylinder assuming that the change of the gas obeys to the equation of state for ideal gas. The value of B was calculated on the basis of the results obtained in the fundamental experiment of ignition delay with a constant volume vessel [11].
B=1.16Tmx10-3 -2.45 (3)
Where the value of B is non-dimensional and Tm means the average temperature in Kelvin between the temperature at injection and ignition timings.
Tm=(Tinj +Tig)/2 (4)
The constant value of C was 4650 K, which refers the empirical equation proposed by Wolfer [1]. The value of A was changed for the kinds of gas induced in the intake port as shown in Table 2.
