Investigation of the influence of local inhomogeneities on wave diffraction during energy deposition

Аuthors

Snazin A. A.^*, Sevchenko V. I.

Mlitary spaсe Aсademy named after A.F. Mozhaisky, St. Petersburg, Russia

*e-mail: alexandersnzn@mail.ru

Abstract

The diffraction of a compression wave generated by localized impulsive energy deposition in a channel with an open outlet was investigated in the presence of periodic geometric obstacles. The relevance of this problem is determined by the fact that the geometry of internal elements can affect pressure redistribution and the structure of reflected flows, and therefore influence the regimes of unsteady gas-dynamic interaction in channels. The aim of the study was to identify how different types of periodic obstacles modify front dynamics, local compression and rarefaction zones, as well as the pressure distribution. To this end, numerical simulations were performed in a two-dimensional unsteady formulation for a viscous compressible gas based on the Navier–Stokes equations with LES closure. The problem was formulated to compare configurations under identical initial and boundary conditions, which made it possible to isolate the contribution of the geometric factor specifically. Three configurations were considered: a smooth channel, a channel with a step expansion, and a channel with successive contractions and expansions. It was shown that the introduction of obstacles qualitatively changes the flow pattern: the step expansion produces a pronounced back-pressure region upstream of the obstacle, whereas the series of contractions and expansions intensifies multiple wave reflections and reduces local peak pressure values while promoting a broader spatial redistribution of energy. Thus, it has been established that a change in the shape of the obstacles leads not only to local deformation of the wavefront but also to a reorganization of the overall wave propagation regime in the channel. The obtained results demonstrate that obstacle geometry acts as a controlling factor in channel wave dynamics.

Keywords:

diffraction; compression waves; energy deposition

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