British Technology Group USA

Garry L Brown

Daniel M Nosenchuck

A lifting body moves relative to a fluid, thereby creating a vortex field in the fluid downstream of the lifting body. The lifting body has a predetermined lift distribution along the length thereof which enhances the velocity component of the fluid flow directed outwardly from the centroid of the vortex field to reduce the strength of trailing vortices. In a preferred embodiment, the lifting body is a wing with a perturbation proximate to the tip end of the wing planform trailing edge.

Lifting body with reduced-strength trailing vortices

The boundary layer of a fluid travelling in a mean-flow direction relative to a surface of a wall of a body is controlled by generating in the fluid a magnetic field B having flux lines along the surface of the wall and an electric current density J traversing the magnetic flux lines in the fluid to form a control region. The magnetic field B and the electric current density J create in the control region a force J.times.B that can stabilize or destabilize flow in the boundary layer. A plurality of such control regions can be arranged in an two-dimensional array of control tiles that are periodically actuated in a controlled, predetermined pattern at a critical frequency that provides boundary layer control over a given area.

Multiple electromagnetic tiles for boundary layer control

The boundary layer of a fluid travelling in a mean-flow direction relative to a surface of a wall of a body is controlled by generating in a near-wall region of the flow a magnetic field B having flux lines parallel to the surface of the wall and an electric current density J traversing the magnetic flux lines in the fluid. An electrolyte or other conductivity-enhancing material is introduced into the flow to provide an electrical conductivity gradient in the near-wall region. The magnetic field B and the electric current density J create in the fluid a force J.times.B having a component normal to the surface of the wall that because of the increased conductivity gradient near the surface can stabilize or destabilize flow in the boundary layer. Numerous aspects of the fluid flow and its interaction with the body can thus be controlled. As examples, shear stress in the fluid at the wall can be decreased, with a corresponding reduction in viscous drag, the characteristics of the acoustic and pressure fields in the fluid surrounding the body can be controlled to reduce noise and fatigue, and boundary layer separation can be inhibited or induced.

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Princeton, NJ, United States of America

Garry L Brown