### Mironov S. Поплавская Т.В. Кириловский С.В.

## Application of high-porous gas-permeable materials in supersonic aerodynamics

### Reporter: Mironov S.

Recently, in the field of supersonic aerodynamics, studies are under way to develop new methods for controlling the aerodynamic forces of aircraft using gas permeable highly porous cellular materials (HPCM). The use of inserts from the HCPM makes it possible to control the aerodynamic forces not only by mechanically changing the size of the gas-permeable insert, but also by the thermal action on the hydraulic resistance of the air flow in the pores of the material. The report presents the results of an experimental and calculated investigation of flow around of a streamwise cylinder with a front cylindrical gas-permeable insert from the HPCM by a supersonic flow (M = 4.85 and 7) and a thin-walled streamwise cylinder with inserted HPCM disks. In all experiments HPCM was used on the basis of a cellular-porous nickel with a 95% porosity value. Wind tunnel experiments with the first model showed that as the length of the insert increases, the model's resistance decreases the more, the larger the pore diameter of the material and the smaller the ratio of the diameter of the model to the pore diameter. The maximum reduction in resistance was obtained by 45%. The magnitude of the decrease in the resistance depends little on the Mach number and the Reynolds number calculated from the diameter of the model, but it depends significantly on the ratio of the diameter of the model to the diameter of the HPCM pores. The latter made it possible to reveal the existence of a geometric criterion for the similarity of flow past bodies with gas permeable porous inserts, in addition to the well-known Mach and Reynolds criteria. Numerical modeling of the flow past the cylinder with the front insert from the HPCM based on the discrete model of the porous-porous material showed good agreement with the data of the drag measurements and the schlieren-visualization of flow and also confirmed the formation of an effective body with a smaller wave drag due to redistribution of the oncoming flow by a porous insert and the exist-ence of a geometric similarity criterion. Experimental and computational studies of the effect of heating the front insert showed the possibility of thermal control of the wave drag of such a model within 12% when the porous insert is heated by 400 degrees. Another approach to controlling supersonic flow past bodies with porous inserts was realized in wind tunnel experiments with a second model. The experiments showed the possi-bility of controlling the aerodynamic drag of this model within 5-7% by heating 400 degrees gas permeable porous disks with a glowing electric discharge. In this case, the control of the aerodynamic drag is based on the thermal (by changing the viscosity) regulation of the transfer of a part of the air from the incoming flow through the porous disks to the bottom of the model and increasing the pressure there. This work was supported by the Russian Foundation for Basic Research (project 015-08-03867).

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