Jet formation in shock-heavy gas bubble interaction

Abstract

The influences of the acoustic impedance and shock strength on the jet formation in shock-heavy gas bubble interaction are numerically studied in this work. The process of a shock interacting with a krypton or a SF 6 bubble is studied by the numerical method VAS2D. As a validation, the experiments of a SF 6 bubble accelerated by a planar shock were performed. The results indicate that, due to the mismatch of acoustic impedance, the way of jet formation in heavy gas bubble with different species is diversified under the same initial condition. With respect to the same bubble, the manner of jet formation is also distinctly different under different shock strengths. The disparities of the acoustic impedance result in different effects of shock focusing in the bubble, and different behaviors of shock wave inside and outside the bubble. The analyses of the wave pattern and the pressure variation indicate that the jet formation is closely associated with the pressure perturbation. Moreover, the analysis of the vorticity deposition, and comparisons of circulation and baroclinic torque show that the baroclinic vorticity also contributes to the jet formation. It is concluded that the pressure perturbation and baroclinic vorticity deposition are the two dominant factors for the jet formation in shock-heavy gas bubble interaction.

Numerical study on the jet formation of simple-geometry heavy gas inhomogeneities

“…A common explanation is that the jet formation is a result of the shock focusing. Zhai et al 28 and Zou et al 29 discussed the effects of the shock strength and gas species on the jet formation and qualitatively concluded that it is the relative position of the shock focusing and leeward surface of the gas bubble that determines the jet formation. Georgievskiy et al 30 summarized the shock focusing locations based on numerical simulations using elliptical bubbles with different elongation ratios and density ratios, under different incident shock strengths.…”

Shock wave interaction with a transcritical fuel droplet

“…Later, these cases were numerically modelled highlighting the feature of the shock-bubble interactions [31]. Since then, many additional cases have been considered, including the bubble composition of SF6 and Krypton [33][34][35][36]. However, these studies are all conducted at atmospheric pressure and room temperature where the fluids are in a gaseous state.…”