NUMERICAL SIMULATION OF SPARK DETONATION INITIATION IN HIGH-PRESSURE HYDROGEN-OXYGEN MIXTURE BY VARIOUS EQUIVALENCE RATIOS

The influence of equivalence ratio on the detonation initiation by spark discharge in high-pressure hydrogenoxygen mixture in the critical mode was investigated. A one-dimensional gas-dynamic model in a chemically reacting gas was applied taking into account the influence of the delayed vibrational excitation of diatomic molecules behinds the shock wave on chemical reactions. The two gas mixture compositions were considered where equivalence ratios equaled α = 1 and α = 0.5. The minimal total energy of the spark discharge, causing the detonation initiation, reduces from 5.4 to 1.35 J when the equivalence ratio changes from α = 1 to α = 0.5. It was found out that a reduction in the total energy by decreasing in the equivalence ratio is caused by growth in the detonation sensitivity of the hydrogen-oxygen mixture via an acceleration of the vibrational excitation of diatomic molecules behinds the shock wave.