Dong Soo Kim

US Patent:

39531260, Apr 27, 1976

Filed:

Nov 8, 1974

Appl. No.:

5/522368

Inventors:

Dong Guen Kim - Xenia OH
Gary Arnold Dubro - Dayton OH

Assignee:

The United States of America as represented by the Secretary of the Air
Force - Washington DC

International Classification:

G01P 336

US Classification:

356 28

Abstract:

The velocity of a fluid flowing through a flow channel, relative to the flow channel, is measured by passing parallel rays of light through the fluid perpendicular to the flow and through an artificially-introduced transfer function device such as a grating or double reflective mirror, and then focusing the light on a photodetector. The basic principle by which embodiments of the invention operate involves the spatial convolution of the light intensity pattern established by the artificially-introduced transfer function with the flowing stream. The transfer function is associated with a known spatial alteration of the light beam. The light intensity pattern resulting from variations in the properties of the flowing stream is characterized by fluctuations which are transported with the flow velocity. These variations of the flowing stream are manifested as localized changes in density, and absorptivity and reflectivity of the light as it traverses the flow channel. This convolution generates a new response function that appears at the electrical output of the photodetector which is periodic and whose base frequency is directly proportional to the flow velocity.