Analysis of the turbulent boundary layer and skin-friction drag reduction of a flat plate by using the micro-blowing technique

Numerical analyses of turbulent boundary layer parameters and skin-friction drag reduction on a flat plate under the effect of air micro-blowing with the use of the SST $k{-}\omega$ turbulence model are performed. The macroscale characteristics of a huge number of microjets are simulated by using a microporous wall model (MPWM) incorporated into ANSYS FLUENT by user-defined functions. Numerical results obtained within the Mach number range $\mathrm{M}=0.2{-}0.5$ (Reynolds number $\mathrm{Re}=2.88\cdot 10^6{-}7.20\cdot 10^6$) confirm the experimental data of other researchers. Furthermore, a slight increase in the boundary layer thickness, displacement thickness, and momentum thickness, as well as a decrease in the velocity gradient and shear friction are well captured. In comparison to a simple flat plate, applying air micro-blowing reduces the skin-friction coefficient by $51 \%$ at the Mach number $\mathrm{M}=0.4$ and blowing fraction of $0.008$. Additionally, the skin-friction coefficient decreases as the blowing fraction and Mach number increase.