Wave amplification in chemically active bubble media

Abstract

A numerical simulation is performed for shock propagation in chemically active two‐phase “liquid‐explosive gas bubbles” media. It is established experimentally that this process is accompanied by formation of a stationary disturbance of the wavetrain form. It propagates with constant velocity exceeding essentially the equilibrium velocity characteristic of the main disturbance. Its maximum amplitude is practically constant and exceeds significantly the amplitude of an incident wave. Such a wave is called a bubble detonation wave or secondary detonation. The basis of this effect is the mechanism of separation of the shock wave in a bubble medium into the main disturbance and precursor [V. K. Kedrinskii, PMTF 4, 29–34 (1968)]. The latter decays quickly. However, in chemically active media these losses are compensated for by the bubble explosion energy, thereby providing the existence of a self‐sustaining regime. The present study is concerned with two approaches. The first one considers the interaction of a strong plane shock wave with a single spherical bubble filled in with a one‐to‐one molar acetylene‐oxygen mixture. It is shown that the refracted wave can initiate this mixture's detonation [V. K. Kedrinskii and Ch. Mader, Proc. XVI Int. Symp. on Shock Tubes and Waves, July 1987, Aachen, Federal Republic of Germany]. The mixture ignition due to adiabatic bubble compression by a weak shock wave is analyzed within the framework of relatively simple kinetics. The second approach is based on a two‐phase model and considers the process of formation of the stationary disturbance in a semi‐infinite active bubble medium. The results obtained are in good agreement with the experimental data [A. I. Sychev and A. V. Pinayev, FGV 3, 22 (1986)].A numerical simulation is performed for shock propagation in chemically active two‐phase “liquid‐explosive gas bubbles” media. It is established experimentally that this process is accompanied by formation of a stationary disturbance of the wavetrain form. It propagates with constant velocity exceeding essentially the equilibrium velocity characteristic of the main disturbance. Its maximum amplitude is practically constant and exceeds significantly the amplitude of an incident wave. Such a wave is called a bubble detonation wave or secondary detonation. The basis of this effect is the mechanism of separation of the shock wave in a bubble medium into the main disturbance and precursor [V. K. Kedrinskii, PMTF 4, 29–34 (1968)]. The latter decays quickly. However, in chemically active media these losses are compensated for by the bubble explosion energy, thereby providing the existence of a self‐sustaining regime. The present study is concerned with two approaches. The first one considers the interaction of a...