Underwater Electromagnetic Turbulent Velocimeter.
Patent Application, Filed 21 Jul 88,
DEPARTMENT OF THE NAVY WASHINGTON DC
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This patent application discloses a velocimeter, comprising a controlled magnetic field source and electric field sensors, the device being flush mounted in a vessel hull. The magnetic source comprises a drive coil which may be energized with either a DC current or an AC current at various desired frequencies. The turns-area product and applied current are selected based on desired sensitivity. When the drive coil is energized, a uniform magnetic field is produced near the surface of, and normal to, the hull. The thickness of the uniform region is governed by the thickness of the boundary layer in the turbulent region. The magnetic field returns through the vessel hull structure in such a way that divB O. Inside the coil, near the outboard external surface of the device, a pair of orthogonally disposed electric field sensors are located for measuring the electric field produced as a result of interaction between the magnetic field and the conductive fluid. Sensor output is then further processed to extract the tangential velocity components. jhd
- Magnetic and Electric Field Detection and Detectors