Control of frictional and total drag by porous media at high Reynolds number wall turbulence conditions

Effective control of frictional drag on a model surface is crucial for achieving total drag reduction at high Reynolds number conditions. This study presents wind tunnel tests at high Reynolds numbers, employing two sets of flat plate models with identical external dimensions. The tests cover incoming Mach numbers ranging from 0.3 to 0.85, corresponding to Reynolds numbers from 2.52 × 106 to 6.35 × 106. The velocity distributions and statistical properties within the turbulent boundary layer were measured using a combination of hot-wire probes and total pressure probes. Total model drag was assessed using a high-precision balance. The results demonstrate that the application of porous media significantly reduces frictional drag, with the cavity arrangement yielding superior drag reduction compared to the non-cavity arrangement. As the Reynolds number increases, the effectiveness of friction drag control diminishes. Moreover, the arrangement of porous media with appropriately chosen parameters can effectively reduce the total drag of the model. Flow field analysis reveals that porous media alter the vortex structure distribution within the boundary layer, increasing small-scale vortex structures and mitigating the impact of large-scale streamwise vortices on the wall, thereby reducing frictional drag. These findings provide important technical support and experimental evidence for the application of porous media in drag reduction at high Reynolds number conditions.