Strong ignition limits for methane-hydrogen mixtures

A study of the auto-ignition behind relected shock in eleven mixtures of CH/sub 4/-O/sub 2/, H/sub 2/-O/sub 2/, and CH/sub 4/-H/sub 2/-O/sub 2/ covering a temperature range of 900 to 2400/sup 0/K and pressure range of 1 to 3 atm was carried out. The induction times were correlated with an equation of the Arrhenius form that was found to be quite satisfactory. All the strong ignition limits determined could be expressed in terms of a constant value expressed in terms of the partial derivative of induction time with respect to temperature at constant pressure, deduced for each mixture from the correlation equation being quite insensitive to variations in initial mixture compositions for the induction time. The values for the strong ignition limits for all test mixtures used were grouped around -0.5 ..mu..sec/K and thermodynamic conditions. This leads to the conclusion that the dominating factor in establishing the actual level of the strong ignition limit is the sensitivity of the induction time to temperature. Comparison of the strong ignition limit of the present H/sub 2/-O/sub 2/ mixture with 90% A dilution to that of the undiluted mixture measured in an earlier study of Meyer and Oppenheim showed that the addition of diluent caused the strong ignition value to decrease from -1.5 ..mu..sec/K to -0.5 ..mu..sec/K