Measuring and testing – Volume or rate of flow – By measuring vibrations or acoustic energy
Patent
1982-04-09
1984-01-10
Goldstein, Herbert
Measuring and testing
Volume or rate of flow
By measuring vibrations or acoustic energy
G01F 132
Patent
active
044247141
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
Embodiments of the invention hereinafter described pertain to devices for the generation of Karman Vortices.
U.S. patent application Ser. No. 06/108,196, filed Dec. 28, 1979 by Thorne et al, now U.S. Pat. No. 4,312,237 issued Jan. 26, 1982, discloses numerous embodiments of narrow, elongate generator plates used for the generation of Karman vortices in a fluid stream. In one embodiment of the 4,312,237 patent, a generator plate has a shedding section wherein an aperture intersects side surfaces of the generator plate to form a leading aperture edge which serves as a shedding corner for the generation of vortices.
U.S. patent application Ser. No. 06/108,066, filed Dec. 28, 1979 by Mahany et al, now U.S. Pat. No. 4,312,236 issued Jan. 26, 1982, discloses an improvement in the generator plates of the 4,312,237 patent wherein a surface disruption is provided on side surfaces of the generator plate in order to eliminate the occurrence of a boundary-layer transition region which would otherwise occur for a range of fluid flow velocities of interest.
Devices constructed in accordance with the teachings of the aforementioned applications have reliably produced remarkably stable vortices over a wide range of fluid flow rates. These devices have functioned particularly well when operated in accordance with the acoustical techniques disclosed in U.S. Pat. No. 3,680,375 to Joy et al. However, tests conducted with these devices using more sophisticated testing equipment have indicated a very slight signal deviation in a neighborhood of one or two flow rates. When using acoustical techniques, these signal deviations appear to be accompanied by a slight audible whistle. Although the signal deviations are so slight as to be imperceptible--and hence negligible--for practically all environments of usage, nevertheless in some exacting environments elimination of the signal deviations is desirable.
DISCLOSURE OF THE INVENTION
In accordance with principles of this invention, numerous structural embodiments are provided for the generation of Karman vortices. According to one embodiment, a vortex generating device includes a narrow generator plate which is immersed in a fluid flow to generate Karman Vortices. The generator plate is oriented with an axis of elongation parallel to the direction of flow of the fluid stream. The generator plate has side surfaces essentially parallel to the direction of fluid flow. The side surfaces have a shedding region wherein an aperture intersects the side surfaces to form a leading aperture edge which serves as a shedding corner at which vortices detach from the generator plate. The aperture further intersects a trailing edge of the generator plate. The aperture includes the leading aperture edge, which may be either curved or linear, and an aperture portion which extends substantially from the leading aperture edge to a point where it intersects the trailing edge of the generator plate.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of preferred embodiments as illustrated in the accompanying drawings in which reference characters refer to the same parts throughout the various views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
FIGS. 1A, 1B, and 1C are side views of vortex generating devices according to differing embodiments of the invention;
FIGS. 2A, 2B and 2C are top views of FIGS. 1A, 1B, and 1C, respectively;
FIG. 3A is a top view of an air flow meter in accordance with an embodiment of this invention including block electronic components coupled to a flow channel with channel walls and sensors for a sonic signal; and
FIG. 3B is a perspective view of the air flow meter of FIG. 3A.
BEST MODES FOR CARRYING OUT THE INVENTION
FIGS. 1A through 1C illustrate side views of generating devices (such as generator plates 10a through 10c) according to various embodiments of
REFERENCES:
patent: 3940986 (1976-03-01), Johnson
patent: 4312236 (1982-01-01), Mahany et al.
patent: 4312237 (1982-01-01), Thorne et al.
Abolins Peter
Ford Motor Company
Goldstein Herbert
Sanborn Robert D.
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