Possibility of Physical Detonation in the Flow of Vibrationally Preexcited Hydrogen in a Shock Tube

Abstract

The direct simulation Monte Carlo method was used to numerically simulate processes in the shock wave front in vibrationally excited hydrogen flowing in the shock tube. The cases of partially and completely excited hydrogen were considered. Equilibrium hydrogen was applied as a pusher gas, but its concentration was 50 times higher than the hydrogen concentration in the low-pressure channel. In addition, the strength of the shock wave was varied by heating the pusher gas. Number of employed processor was equal to 274. The modeling domain was split into 274 sub-domains, in each of which the evolution of the system was simulated with a single processor. The parameters of the wave in the case of physical detonation become dependent on the vibrational-to-thermal energy conversion and independent of the way of its initiation. This served as a criterion for the appearance of the physical detonation in the numerical experiment. It turned out that this phenomenon occurs until the degree of pre-excited hydrogen is not less than 85% in the low pressure channel. And the vibrational temperature is not less than 2800 K.