Abstract
This study is focused on the propagation behavior and attenuation characteristics of a planar incident shock wave when propagating through an array of perforated plates. Based on a density-based coupled explicit algorithm, combined with a third-order MUSCL scheme and the Roe averaged flux difference splitting method, the Navier–Stokes equations and the realizable k-ε turbulence model equations describing the air flow are numerically solved. The evolution of the dynamic wave and ring vortex systems is effectively captured and analyzed. The influence of incident shock Mach number, perforated-plate porosity, and plate number on the propagation and attenuation of the shock wave was studied by using pressure- and entropy-based attenuation rates. The results indicate that the reflection, diffraction, transmission, and interference behaviors of the leading shock wave and the superimposed effects due to the trailing secondary shock wave are the main reasons that cause the intensity of the leading shock wave to experience a complex process consisting of attenuation, local enhancement, attenuation, enhancement, and attenuation. The reflected shock interactions with transmitted shock induced ring vortices and jets lead to the deformation and local intensification of the shock wave. The formation of nearly steady jets following the array of perforated plates is attributed to the generation of an oscillation chamber for the inside dynamic wave system between two perforated plates. The vorticity diffusion, merging and splitting of vortex cores dissipate the wave energy. Furthermore, the leading transmitted shock wave attenuates more significantly whereas the reflected shock wave from the first plate of the array attenuates less significantly as the shock Mach number increases. The increase in the porosity weakens the suppression effects on the leading shock wave while increases the attenuation rate of the reflected shock wave. The first perforated plate in the array plays a major role in the attenuation of the shock wave.
Highlights
Introduction published maps and institutional affilWhen a shock wave propagates through a porous barrier, it is accompanied by a series of complex shock wave propagation and interaction behaviors
It is of great significance to study the propagation behavior of a shock wave when it passes through a perforated-plate array and reveal the mechanisms that lead to the change in the shock wave intensity
The results showed that the shock wave attenuation strongly relied on the porosity and the angle of inclination of the perforated plates
Summary
Three-dimensional time-averaged Navier–Stokes equations were used to describe the high-speed, compressible, viscous, and unsteady air flow field. The governing continuity, momentum, and energy equations are expressed as follows:. Where ρ is the density; t is the time; V is the velocity vector; τ is the viscous stress tensor;. The realizable k-ε turbulence model [23] was adopted in this study because of its high reliability and accuracy, and short computational time relative to other most popular turbulence models including the standard k-ε model, RNG k-ε model, SST k-w model, and RSM in simulations of complex flow fields such as round jets and multiple jets [24], and transient, compressible, and viscous turbulent flows [25]. The turbulent kinetic energy and the rate of turbulent dissipation transport equations are respectively expressed as follows:. The molecular viscosity of air is calculated with the three-coefficient Sutherland formula
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