Computer simulation of the interaction between a shock wave and a wall shielded by an inhomogeneous gas suspension layer

In modern technologies of pneumatic transport, fluidization, and polymer spraying, gas-dispersed media are widely used. Of particular interest, from the point of view of dynamic loading of structures, are shock-wave processes in gas-dispersed mixtures in the vicinity of the walls. The use of computer modeling methods makes it possible to reduce time and material costs for improving designs and optimizing technological process parameters. A hybrid large-particle method of second order approximation with a nonlinear correction, Superbee at the Eulerian stage and VanLeer at the Lagrangian stage, was used for the calculations. The algorithm is implemented as multi-threaded solver code, with processing of graphical results in a separate parallel process. A detailed numerical simulation of the characteristic stages of the interaction of a shock wave with a wall shielded by a layer of finely dispersed gas suspension with a cylindrical region of increased particle density was carried out. The beginning of the process (before the interaction of a plane shock wave passing into the layer of gas suspension with inhomogeneity) is one-dimensional in nature. Further development of the physical picture is associated with a significant restructuring of the flow. The shock wave enveloping the cylindrical boundary of the inhomogeneity converges to the plane of symmetry with the formation of a focusing effect. Due to baroclinic instability (mismatch of pressure and density gradients), a vortex zone is formed on the surface of the highdensity boundary. As shown by a detailed analysis of the calculation results, the most significant (more than an order of magnitude relative to the initial state) surges in pressure and density of the gas suspension are caused by the interactions of a focused shock wave that has passed into the inhomogeneity, and then an incident reflected composite shock wave pulse. The results obtained have theoretical and applied significance. New physical effects of shock wave reflection from a wall shielded by a layer of gas suspension with a cylindrical region of increased density of the dispersed fraction have been revealed. The reasons for the sequence of bursts in pressure and density of the mixture, which can lead to ignition and detonation of the combustible dispersed phase, are determined. The developed numerical algorithm and computer modeling technique can form the basis for the analysis of shock wave phenomena in the vicinity of the walls of structures and the justification of rational parameters of technological gas-powder technologies.

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