Active Control of Ionized Boundary Layers

Active control of ionized boundary layers

The challenging problems, in the field of control of chaos or of transition to chaos, lie in the domain of infinite-dimensional systems. Access to all variables being impossible in this case and the controlling action being limited to a few collective variables, it will not in general be possible to drive the whole system to the desired behaviour. A paradigmatic problem of this type is the cont...

Control of turbulent boundary layers

The objective of this paper is to give an overview of recent progress on boundary layer control made by the author’s research group at University of California, Los Angeles. A primary theme is to highlight the importance of a certain linear mechanism and its contribution to skin-friction drag in turbulent boundary layers—and the implication that significant drag reduction can be achieved by alt...

Numerical Studies of Active Control of Turbulent Boundary Layers Using Transverse Travelling Waves

Turbulence control in the form of transverse wall motion is employed numerically (direct numerical simulation). Results from a turbulent boundary layer subjected to spanwise wall forcing in the form of a streamwise travelling wave are presented for the first time. Both total and phase averaging have been utilized to examine the statistical behaviour of the turbulence affected by the wall forcin...

A Comparison of Active and Passive Methods for Control of Hypersonic Boundary Layers on Airbreathing Configurations

Active and passive methods for control of hypersonic boundary layers have been experimentally examined in NASA Langley Research Center wind tunnels on a Hyper-X model. Several configurations for forcing transition using passive discrete roughness elements and active mass addition, or blowing, methods were compared in two hypersonic facilities, the 20-Inch Mach 6 Air and the 31-Inch Mach 10 Air ...

Micro Electro Kinetic Actuator (MEKA) Arrays for Active Sublayer Control of Turbulent Boundary Layers