# The Period of Ignition Delay for Methane-Air Mixture with Hydrogen and Ethylene Additives
## 5 Influence of Mixture Composition and Initial Conditions on the Ignition Delay Period  
The article presents the set of calculations and defines the regularities of changing the ignition delay period \(\tau\) of methane and additives mixture depending on the mass fractions of combustible components at pressures P = 1-8 bar and at initial temperatures T = 900-1100 K. The following ignition conditions are considered for the most characteristic modes:  
- mode \(N\) 1-P = 1 bar, T= 1100 K;  
- mode \(N\) 2-P = 2 bar, T= 1000 K;  
- mode \(N\) 3-P = 2 bar, T= 1100 K;  
- mode \(N\) 4-P = 2 bar, T= 1200 K;  
- mode \(N\) 5-P = 4 bar, T= 900 K;  
- mode \(N\) 6-P = 8 bar, T= 900 K.  
The results obtained by the ignition of methane + hydrogen + ethylene mixture with air at the oxidizer excess coefficients \(\alpha\) = 0.5-2 are presented in Tables 2-4. Note that when processing the results, it is assumed that the ignition delay period should not exceed 0.5 s. In the case of calculated excess of this value, it is considered that the mixture is difficult to ignite and is excluded from further consideration. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{3}{c}{**Mass Fraction**} & \multicolumn{1}{c}{**Mode**} & \multicolumn{1}{c}{**Mode**} & \multicolumn{1}{c}{**Mode**} & \multicolumn{1}{c}{**Mode**} & \multicolumn{1}{c}{**Mode**} & \multicolumn{1}{c}{**Mode**} \\ \hline
**CH\({}_{4}\)** & **H\({}_{2}\)** & **C\({}_{2}\)H\({}_{4}\)** & **N 1** & **N 2** & **N \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Mass Fraction**} & \multicolumn{2}{c}{**Mode**} & \multicolumn{2}{c}{**Mode**} & \multicolumn{2}{c}{**Mode**} & \multicolumn{2}{c}{**Mode**} & \multicolumn{2}{c}{**Mode**} & \multicolumn{2}{c}{**Mode**} & \multicolumn{2}{c}{**Mode**} \\ \hline
**CH4** & **H2** & **C2H4** & **N^1**1** & **N^2**2** & **N^3**3** & **N^4**4** & **N^5**5**5 & **N^6**6** \\ \hline  
\hline \hline \end{tabular}
\end{table} 
Table 4: The period of the ignition delay for the mixture of methane + hydrogen + ethylene with air for different modes at \(\alpha\) = 2.0. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Mass Fraction**} & \multicolumn{2}{c}{**Mode**} & \multicolumn{2}{c}{**Mode**} & \multicolumn{2}{c}{**Mode**} & \multicolumn{2}{c}{**Mode**} & \multicolumn{2}{c}{**Mode**} \\ \hline
**CH4** & **H2** & **C2H4** & **N^1**1** & **N^2**2** & **N^3**3** & **N^4** & **N^5**5** & **N^6**6** \\ \hline
1.000 & - & - & 0.3390 & - & 0.1682 & 0.0413 & 0.4612 & 0.2040 \\
0.980 & 0.020 & - & 0.2749 & 0.4549 & 0.1368 & 0.0354 & 0.4315 & 0.1967 \\
0.960 & 0.040 & - & 0.2224 & 0.3545 & 0.1113 & 0.0303 & 0.4084 & 0.1910 \\
0.940 & 0.060 & - & 0.1803 & 0.2825 & 0.0909 & 0.0256 & 0.3893 & 0.1862 \\
0.920 & 0.080 & - & 0.1464 & 0.2290 & 0.0745 & 0.0218 & 0.3731 & 0.1820 \\
0.900 & 0.100 & - & 0.1194 & 0.1879 & 0.0611 & 0.0185 & 0.3589 & 0.1784 \\
0.980 & - & 0.020 & 0.2690 & 0.4622 & 0.1340 & 0.0339 & 0.4361 & 0.1915 \\
0.960 & - & 0.040 & 0.2132 & 0.3621 & 0.1067 & 0.0278 & 0.4110 & 0.1802 \\
0.940 & - & 0.060 & 0.1692 & 0.2900 & 0.0854 & 0.0227 & 0.3866 & 0.1695 \\
0.920 & - & 0.080 & 0.1345 & 0.2369 & 0.0683 & 0.0189 & 0.3634 & 0.1598 \\
0.900 & - & 0.100 & 0.1070 & 0.1970 & 0.0552 & 0.0154 & 0.3417 & 0.1506 \\
0.980 & 0.005 & 0.015 & 0.2697 & 0.4581 & 0.1344 & 0.0343 & 0.4356 & 0.1928 \\
0.960 & 0.010 & 0.030 & 0.2134 & 0.3553 & 0.1068 & 0.0278 & 0.4121 & 0.1827 \\
0.940 & 0.015 & 0.045 & 0.1684 & 0.2817 & 0.0851 & 0.0232 & 0.3906 & 0.1736 \\From Tables 2-4, it can be seen that the value of the ignition delay period in the air of the fuel based on methane with the addition of hydrogen and ethylene can be reduced up to 3 times relative to the ignition delay period of pure methane with air. It is shown that the minimum values of the ignition delay period were obtained for a mixture of methane with hydrogen.