Active control of turbulent boundary layer-induced sound transmission through the cavity-backed double panels

Turbulent boundary-layer control with plasma actuators.

This paper reviews turbulent boundary-layer control strategies for skin-friction reduction of aerodynamic bodies. The focus is placed on the drag-reduction mechanisms by two flow control techniques-spanwise oscillation and spanwise travelling wave, which were demonstrated to give up to 45 per cent skin-friction reductions. We show that these techniques can be implemented by dielectric-barrier d...

Active/Passive Control of Sound Radiation from Panels using Constrained Layer Damping

Active Control of Cavity Shear Layer Oscillation

Influence of externally forced initial flow conditions on axisymmetric cavity shear layer were studied. A sinusoidally heated strip upstream of the cavity excited Tollmien-Schlichting waves which, after amplification by the boundary layer, were introduced to the cavity shear layer. By choosing forcing frequencies within the range of shear layer receptivity, it was possible to control frequency ...

Turbulent Boundary-Layer Separation

This article summarizes our present understanding of the physical behavior of two-dimensional turbulent separated flows, which occur due to adverse pressure gradients around streamlined and bluff bodies. The physical behavior of turbulence is flow dependent, so detailed experimental infor­ mation is needed for understanding such flows and modeling their physics for calculation methods. An earli...

Turbulent boundary layer equations

We study a boundary layer problem for the Navier-Stokes-alpha model obtaining a generalization of the Prandtl equations conjectured to represent the averaged flow in a turbulent boundary layer. We solve the equations for the semi-infinite plate, both theoretically and numerically. The latter solutions agree with some experimental data in the turbulent boundary layer.