Experimental Study of Turbulent Drag Reduction on a Plate Using Microbubbles

A set of testing apparatus to study the effects of microbubbles drag reduction was designed in this paper. The turbulent boundary layer was formed on the surface of a 2D flat plate. The behaviors of the microbubbles were visualized quantitatively using the high speed camera. The skin-friction drag was measured using balances. The effects of the drag reduction with different air flow, free-stream velocity and buoyancy were analyzed. It shows that the microbubbles are effective in reducing the skin friction in high Reynolds number regime of 10⁶. It proves that microbubbles can significantly reduce skin-friction of the solid wall and the drag reduction radio is up to 36%. Results show that when the gas flow rate increases, the skin-friction reduction ratio increases.