Friction Drag Reduction Mechanism Under DBD Plasma Control
This work aims to understand the mechanism behind friction drag reduction in a dielectric barrier discharge (DBD)-plasma-controlled flat-plate turbulent boundary layer (TBL). Streamwise-oriented DBD plasma actuators are deployed to generate streamwise counter-rotating vortices in the TBL. The variation in the local friction drag is measured using a single hotwire, and the change in the flow structure is captured using a high-speed PIV. At a voltage V a of only 4.25 kV, the drag reduction over an area (90 mm long and 200 mm wide) behind the plasma actuators reaches 14%. In fact, the drag reduction area stretches longitudinally to about 300 mm or 2000 wall units. The drag reduction is found to be linked to the decrease in the near-wall turbulent kinetic energy production, pointing to that the plasma-actuator-generated streamwise vortices interrupt effectively the turbulence generation cycle, thus stabilizing near-wall velocity streaks and resulting in friction drag reduction.
KeywordsTurbulent boundary layer Drag reduction Control mechanism DBD plasma control
C. W. Wong wishes to acknowledge support by the National Natural Science Foundation of China through grant 11502060 and from the Research Grants Council of the Shenzhen Government through grants JCYJ20160531193045101 and JCYJ20150513151706565.
- 3.Wong CW, Zhou Y, Li YZ, Zhang BF (2015) Skin friction drag reduction based on plasma-induced streamwise vortices. In: Fluid–structure-sound interactions and control. Springer, Berlin, Heidelberg, pp 139–144Google Scholar