ANALYSIS OF THE TURBULENT BOUNDARY LAYER AND SKIN-FRICTION DRAG REDUCTION OF A FLAT PLATE BY USING THE MICRO-BLOWING TECHNIQUE
Hasan Najafi Khaboshan, Elnaz Yousefi, Jelena Svorcan
Abstract
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 $$\text{M}=0.2{-}0.5$$ (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 $$\text{M}=0.4$$ and blowing fraction of 0.008. Additionally, the skin-friction coefficient decreases as the blowing fraction and Mach number increase.