Prediction of Composition Limits for Detonation of Hydrogen-Oxygen-Diluent Mixtures

Two different methods of predicting Chapman-Jouguet detonation limits in hydrogen-oxygendiluent mixtures are presented for a model of the detonation wave comprising a shock wave followed by an ignition delay region and a combustion legion. In the first method, a constant ignitiontemperature criterion for the gas behind the shock wave is employed to correlate experimental data; in the second method explosion limits determined from chain branching considerations are employed. Various degrees of rotational and vibrational relaxation behind the shock in the ignition delay region are assumed for both methods to obtain three sets of temperature and pressure conditions behind the shock wave. Both methods are employed to predict detonation limits for various mixtures for which experimentally determined values are available in the literature. It is shown tha t the constant temperature criterion computed for a gas having complete rotational relaxation but no vibrational relaxation provides the best statistical correlation with experimental values obtained from the literature.