Passive Skin Friction Control Near Turbulent Separation – Preliminary Results

Abstract

The paper deals with experimental analysis of passive skin friction control method applied for a high Reynolds number turbulent boundary layer close to separation. A proposed new method is based on the mechanism of scale interaction observed in the wall bounded flows known as amplitude modulation of small scales by large-scale motion. The applied control technique introduces artificially amplification of the modulation mechanism using a corrugated surface in the direction of flow at specific ratio of surface waving parameters. Preliminary results show that the method can be use in an efficient way to postpone the turbulent boundary layer separation for high Reynolds number, where methods based on classical turbulizers fail. This method introduces reorganization of turbulence production, which introduces asymmetry between sweep and ejection events. This results in positive skewness of streamwise fluctuations and additionally increases the momentum near the wall. The momentum is increased only in the inner part of boundary layer. The persistent of the developed flow control method is permanent farther downstream the corrugated wall.