ИСТИНА

The report presents the results of numerical simulation of two-dimensional laminar flows near a regular system of cylinders, forming a plane lattice perpendicular to the velocity vector of the oncoming supersonic flow. A multi-block computing technology is applied using local curvilinear grids adapted to the surface of bodies and having finite areas of overlap with a global rectangular grid. With a sequential increase and decrease in the Mach number of the oncoming flow, several rearrangements of the flow structure near the grid were found. A multiple hysteresis was revealed, which is expressed in the fact that the flow structure and aerodynamic loads on the lattice elements depend not only on the Mach number, but also on the history of its change. Four flow patterns were revealed, the new of which was a pattern with unsteady periodic self-oscillations of the flow in the near wake behind the lattice elements. The implemented flow patterns and the boundaries of transition from one flow pattern to another depend on the pre-history of the change in the Mach number. Using the example of the flow around the finite lattice of cylindrical rods with a permeability of 80%, three ranges of flow ambiguity and the corresponding hysteresis of the Mach number characteristics were revealed. The first is associated with restructuring between the collective and local flow regimes of the lattice elements. The second is conditioned by the restructuring of the near wake behind the cylindrical elements as a result of interaction with local shock-wave systems from neighboring lattice elements. The third type of hysteresis is associated with the occurrence of unsteady periodic flow in the wake of the lattice elements. The work was carried out with a partial financial support of the Russian Foundation for Basic Research (Project No. 19-01-00242) and partially under the state task of the ICAD RAS. The calculations were carried out on MVS-100 K at Interdepartmental supercomputer center of the Russian Academy of Sciences.