JPS6361604B2 - - Google Patents

Description

Claim 1: A member having leading and trailing edges disposed with side surfaces parallel to the direction of fluid flow and extending across the fluid flow; and means for forming breakaway corners for generating Karman vortices in the vortex array, the member being a narrow elongated plate member 10, the leading edge 16 of which The breakaway corners 32 are adapted to generate a substantially laminar boundary layer near the leading edge 16 , with each of the breakaway corners 32 extending over at least one of the front opening edges 28 of the opening 26 , i.e., at least one of the sides 20 of the elongated plate member 10 . Apparatus characterized in that the opening 26 is formed by two intersecting recesses and the opening 26 is near the leading edge 16 of the elongated plate member 10.

2. The maximum distance d from the front opening edge 28 of the opening 26 to the rear opening edge 30 along the fluid flow direction is between 5 and 5 of the thickness w of the elongated plate member 10.
Apparatus according to claim 1 within the range of 30 times.

3. The length a from the front edge 16 of the elongated plate member 10 to the front opening edge 28 is the length a of the elongated plate member 10.
3. A device according to claim 1 or 2, wherein the thickness w is less than 5 times, preferably less than 3 times.

4. The device according to any one of claims 1 to 3, wherein the front opening edge 28 has a substantially continuous arcuate portion in a plane that includes one side of the elongated plate member 10. .

5. A member having a leading edge and a trailing edge arranged to have side surfaces parallel to the direction of the fluid flow and extending across the fluid flow, and a member having a vortex array in a direction substantially parallel to the fluid flow. and means for forming a breakaway corner for generating a Karman vortex in a fluid flow, said member being a narrow elongated plate member 10, said leading edge 16 being a part of said leading edge 16. The breakaway corner 32 is attached to the leading edge 16 of the elongate plate member 10 and is adapted to generate a boundary layer in the vicinity of substantially laminar flow. A device characterized in that it is formed by a wire member 36 oriented upstream of said leading edge 16.

6. The apparatus of claim 5, wherein said wire member (36) is connected to said leading edge (16) at two points and is arcuate with respect to said leading edge (16) to define said opening (26).

7. The distance i from the wire member 36 to the leading edge 16 along the fluid flow direction is within a range of 5 to 30 times the thickness w of the elongated plate member 10. The device according to item 6.

8 The length L of the elongated plate member 10 in the direction of the fluid flow is equal to the thickness w of the elongated plate member 10.
8. A device according to any one of claims 1 to 7, which is within the range of 15 to 100 times.

9. The side surface 20 of the elongated plate member 10 is gradually tapered toward the leading edge 16 and intersects to form the leading edge 16. The device according to item 1.

10 The separation corner portion 32 protrudes on a plane perpendicular to the direction of the fluid flow, and the elongated plate member 1
10. The device according to claim 1, wherein the device has an effective vortex generation length c that is 2 to 9 times the zero thickness w.

11. The apparatus of any one of claims 1 to 10, wherein the side surface 20 of the elongated plate member 10 is tapered toward the trailing edge 18 of the elongated plate member 10.

12. Claims 1 to 11, in which each of the side surfaces 20 has a surface break 52 arranged symmetrically with respect to the breakaway corner 32 for generating boundary layer turbulence in the fluid flow. The device according to any one of the following.

13 The elongated plate member 10 is disposed in the channel 34 and has a diameter of 1/5 or less, preferably 1/1 of the diameter D of the channel 34.
Claims 1 to 12 that close 5 or less
Apparatus according to any one of paragraphs.

BACKGROUND OF THE INVENTION It is well known that a fluctuating flow field consisting of vortices exists behind objects in relatively moving fluids. That is, when an object is passing through a fluid, or when a fluid is passing through an object, a fluctuating flow field consisting of vortices created alternately from each side of the object appears. This fluctuating flow field is more commonly referred to as a Karman vortex street or trace.
Also, as is well known, the rate at which vortices develop after an object is related to the relative velocity between the object and the fluid flow.

Vortex generators known in the art include objects of circular, triangular or rectangular cross section. Generally, such vortex generators are sufficiently large or blunt relative to other cross-sectional dimensions to generate a stable vortex train.
It has a cross section with dimensions perpendicular to the direction of flow. Similarly, when existing vortex generators are installed within a restricted fluid path, such as a pipe, a stable vortex train is often generated only when the generator produces a specified closure ratio for the fluid path. For example, some vortex generators currently available on the market perform well when occluding 30 percent of the cross-sectional area of the flow path.

Unfortunately, although existing vortex generators are designed to make the vortex train as stable as possible, vortex stability and related measurement accuracy are inherently limited due to the geometry of the generator used. limited to. In some respects, the particular geometry of existing generators creates disturbances that make measurements inaccurate.

Regarding the above, it is well known that a ponding area appears on the upstream face of an object immersed in a relatively moving fluid. This deliberation zone constitutes a pressure zone near the upstream face. The size of the ponding zone and the magnitude of the associated pressure depend on the geometry of the upstream surface. As the fluid moves against the object, the thinking zone tends to move away from the lateral surface centered on the upstream surface, thereby creating a pressure difference, while a flow-induced pressure gradient is generated downstream along the object surface. . The magnitude of the pressure difference as the thinking zone moves is important because the point and timing of the departure of the vortex from the immersed object depend on these pressure gradients. The clearance zone created by the relatively rounded upstream face of existing generators accelerates the pressure differential and causes non-uniform shedding of the vortices from the generator. Such non-uniformity results in erroneous measurements of vortex generation rate.

Also, the geometry of existing generators produces highly turbulent wakes. The more turbulent the flow, the larger the wake, which adds pressure resistance to the generator and fluid. This pressure resistance adversely affects the velocity of the fluid and the vortices generated at a proportional velocity. Therefore, turbulence caused by existing vortex generators has a detrimental effect on flow measurements.

Various types of existing flow meters, including those that measure velocity and/or fluid flow rate, utilize vortex generators to measure flow rate. However, many vortex generators are unable to generate vortex streets with significant stability over a wide range of fluid flow rates. the result,
The vortices are either not measured or "missing" if the vortices were detected. (Applicants acknowledge that the "stability" of a vortex depends on the strength of the vortex formation and the sensitivity of the equipment used to detect the vortex. However, "stability" as used herein refers to the quality of the vortex for a constant or stationary detection device, i.e. the production of a continuous and fairly well-formed vortex representing the fluid flow rate.) The vortex train obtained by existing generators is unstable , the vortex count measurements must be averaged over time to accurately represent the flow rate. The longer the averaging time interval, the less accurate the instantaneous flow measurement.

It is therefore an object of the embodiments of the invention described below to provide a device for generating stable vortices.

The benefit of these embodiments is that they ensure a stable vortex with reduced wake-induced pressure differences in the area of the vortex generator.

Another benefit of embodiments of the present invention is the ability to accurately measure the rate of Karman vortex development.

Regarding the above, viscosity causes the velocity of the fluid to zero at points along the surface of the generator plate used in the preferred embodiment. However, at a very small distance from the surface of the generator plate, the fluid velocity reaches the general velocity characteristic of fluid flow. A thin fluid layer, known as a boundary layer, therefore forms on the surface of the immersion plate, containing a large velocity gradient.

The boundary layer initially starts with virtually no thickness at the leading edge of the plate (formed in the direction of fluid flow). Near the leading edge, the boundary layer flow is essentially laminar. The boundary layer increases in thickness in the downstream direction as the viscous effects increase due to the increase in plate area. However, as the boundary layer thickens and the flow rate increases, it becomes unstable and the flow within the layer breaks down or “cuts”.
The flow becomes turbulent. This change from a layered to a turbulent boundary layer is not an abrupt change, but rather occurs through a boundary layer transition zone where both viscous and turbulent effects are present. In fact, the viscous effects in the transition zone eventually replace the turbulent effects and become a purely turbulent boundary layer.

The particular point along the surface of the plate at which the transition zone occurs is related to the Reynolds number. In this regard, the Reynolds number at any point downstream from the leading edge of the plate depends on both the velocity of the fluid and the distance of that point from the leading edge. It is recognized that the transition zone occurs at a Reynolds number of approximately 105 in flat plates. Therefore,
Points along the surface of the plate that have a Reynolds number in this vicinity are generally in the boundary layer transition zone.

The location of the boundary layer transition area is not necessarily constant. That is, a plate has a transition area that is associated with a first range of surface points for a first velocity of fluid flow, but the transition area is associated with a second range of surface points for a second velocity of fluid flow. Move to.

However, irrespective of whether the boundary layer transition zone is along a flat plate immersed in the fluid flow, the transition zone is associated with unfavorable frictional resistance. This frictional resistance is significant and, due to its erratic nature, generally has an unintended impact on the fluid flow velocity in the transition area.

As is clear from the above discussion, if the boundary layer displacement zone occurs near the detection or aperture zone of a device such as a vortex flowmeter, then the irregular frictional drag can significantly disturb the rate and/or pattern of vortex formation, resulting in Measurements based on this will be extremely inaccurate. For example, the structure of any vortex generator may limit the boundary layer transition area to a specific environment.
If the structure appears near the sensing area or aperture of the flow meter for fluid flow velocity at a flow rate, the flow meter's measurement of that fluid velocity will be inaccurate.

Therefore, another object of the embodiments of the present invention is to provide a vortex train generator capable of generating a stable vortex train over a predetermined fluid flow velocity range in a given environment. Such embodiments advantageously eliminate the occurrence of boundary layer transition zones at critical locations along the originating device, such as those that occur over a range of fluid flow speeds.

SUMMARY In accordance with the principles of the present invention, a number of structural embodiments are provided for generating Karman vortices. According to one embodiment, the vortex generator has a narrow generator plate that is immersed in the fluid flow to generate the Karman vortices. The generator plate is oriented with its axis of extension parallel to the direction of fluid flow. The sides of the generator plate are essentially parallel to the direction of fluid flow. These sides have shed areas forming open corners where the vortices leave the generator plate. Moreover, the various embodiments separately exhibit different shapes of the leading edge and the aperture area of the generator plate.

According to another embodiment, the generator member is attached to the leading edge of the generator plate. The generator member is oriented upstream parallel to the axis of extension of the generator plate.

According to another aspect of the invention, the sides of the generator plate are provided with at least one radial slot or the like for introducing boundary layer turbulence into the fluid flow, in order to eliminate the creation of possible boundary layer transition zones. It has two surface breaks or discontinuities.

[Brief explanation of drawings]

These and other objects, features and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments, which are illustrated in the accompanying drawings. In the accompanying drawings, the same reference numerals indicate the same parts in each figure. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

1A to 1F are side views of vortex generating devices according to various embodiments of the present invention; FIGS. 2A to 2B are plan views of vortex generating devices according to various embodiments of the present invention; FIG. 3A is a top view of a vortex generating device according to various embodiments of the present invention; FIG. 3 is a front view of the device shown in FIG. 3A inserted into a flow path; FIGS. 4A and 4B are respective top views of an embodiment of the present invention; FIG. side view; Figures 5A and 5B are top views of a vortex generator according to an embodiment of the invention, where the generator is inserted into a flow path between a transmitting device and a receiving device attached to the flow path; and a front view; FIGS. 6A and 6B are a plan view and a side view, respectively, of a vortex generator according to an embodiment of the invention with a sensor attached to the rear opening edge; FIGS. 7A and 7B are a diagram showing a detection device FIG. 8 is a side view of a vortex generator according to another embodiment of the invention; FIG. 9 is a 9- 9 is a cross-sectional view of the embodiment of FIG. 9 taken along line 9; FIG. 10 is a side view of a vortex generator according to another embodiment of the invention; and FIG. 11 is a cross-sectional view of the embodiment of FIG. 10 taken along line 11--11. FIG. 3 is an example cross-sectional view.

DETAILED DESCRIPTION OF THE DRAWINGS Figures 1A to 1F illustrate vortex generators (such as generator plates 10a to 10f) according to various embodiments of the present invention. FIGS. 2A to 2C show (generator plate 10
In addition to illustrating a top view of yet another embodiment according to the invention (comprising 10g, 10h, and 10i), the axis of extension 12 for each generator plate 10 in the various embodiments disclosed herein is also selectively shown. extension axis 12;
Each generator plate 10 thus has an arrow 14 (from left to right)
oriented parallel to the direction of fluid flow as shown in . In addition, in each figure except FIG. 3A, FIG. 3B, and FIG. 5B, the fluid flows in the direction from the left to the right.

Generator plate 10 according to the present invention may be made of any material or combination of materials, including plastic or metal. Although the generator plate 10 is mounted in a stand-up aerodynamic configuration, embodiments of the invention may also be incorporated into an surrounding fluid flow, such as a pipe.

In the direction of flow, each generator plate has a leading edge 16 and a trailing edge 18. When entering the extension axis 12,
The leading edge 16 of the generator plate 10 is separated by a length L from the trailing edge 18.
separated from As shown in FIGS. 2A-2C, each generator plate 10 also has a width W essentially perpendicular to the axis of extension 12. As shown in FIGS. The generator plate 10 is a narrow elongated member, and its length to width ratio L:W is preferably 15:
It ranges from 1 to 100:1. Ratio L in this range:
W gives the generator a streamlined shape to reduce wake turbulence and associated pressure drop.

Each generator plate 10 has two side surfaces 20 extending from the leading edge 16 to the trailing edge 18. The side surface 20 is the second A
The side surface 20, which is primarily parallel to the extension axis 12 as shown in FIG. and rear part 2
4, in which the figures of FIGS. 2A, 2B and 2C show different embodiments in which the front portion 22 of the side surface 20 has a different profile.

In the embodiment of FIG. 2A, the front portion 22g of the side surface 20g is essentially straight when viewed from above, and the leading edge is intersected by the extension axis 12 at an angle alpha α preferably in the range of 5 to 30 degrees. Forms 16g.

In the embodiment of FIG. 2B, the front portion 22h of the side surface 20h tapers inwardly to form a leading edge 16g.

In the embodiment of FIG. 2C, the front section 22i remains substantially parallel to the axis of extension 12, but the front section 22i' intersects the front section 22i at an angle beta β, preferably in the range of 5 degrees to 30 degrees. .

Each of the embodiments shown in FIGS. 1A to 1F shows a height dimension h that is perpendicular to both the length dimension L and the width dimension W. In this regard, the leading edge 16 of each generator plate 10 according to the invention has an essentially straight leading edge 16 with respect to the height dimension h, or
As shown in FIG. 1E, it has a leading edge 16e that is curved relative to the height h.

Generator plate 10 according to a different embodiment of the invention has an aperture section consisting of an aperture 26 that intersects side surface 20 and extends through generator plate 10 along width dimension W. In this regard, the aperture 26 may be a suitable recess in the side surface 20, or the aperture 26 may extend completely through the generator plate 10.

Although the aperture 26 can take on a number of geometric shapes, as described below for the embodiment of FIGS. 1A-1D, the aperture 26 in each embodiment
As shown, it has a front opening edge 28 and a rear opening edge 30 in the flow direction. The front opening edge 28 is the generation plate 1
An opening corner 32 that is as sharp as possible is formed so as to intersect with the side surface of 0 and can be seen from above in FIGS. 2A to 2C. However, from Figure 1A
As seen from the side in Figure D, the front opening edge 28 is preferably a continuous curve without sharp discontinuities.

As mentioned above, the apertures 26 are shown in FIGS. 1A to 1D.
Several exemplary geometrical shapes are presented as shown in the figure. The embodiment of FIG. 1A shows a circular aperture 26a; the embodiment of FIG. 1B shows a substantially elliptical aperture 26b having a major axis parallel to the extension axis 12; The embodiment of FIG. 1B shows a substantially elliptical opening 26c having a vertical major axis; and the embodiment of FIG. Intersecting substantially “D” shaped openings 2
6d is shown.

1A through 1D show distance d, which is the longest distance from the front opening edge 28 to the rear opening edge 30. FIGS.
That is, the distance d is from the most upstream portion of edge 28 to edge 3.
This is the distance to the most downstream part of 0. Regarding the width W of the generator plate 10, the ratio d:W is preferably from 5:1.
Set the range to 30:1.

In each embodiment of FIG. 1A to FIG. 1D,
The opening corner portion 3
2 effectively extends only partially along the front opening edge 28. The length c is different for each example, but in each example, the length c is (represented by b)
The height dimension h must be shorter than the protrusion length from the front opening edge 28. If the portions of the front opening edge 28 that are not included within the distance c are sloped smoothly as shown, these portions of the front opening edge 28 can advantageously have as little disturbance as possible. Generator plate 10
The ratio c:W is preferably in the range of 2:1 to 9:1.

The distance from the most upstream point of the front opening edge 28 must be sufficiently downstream from the leading edge 16 of the plate 20 to accommodate the front portion 22 of the sides. In this regard, the front portion 22 (projects beyond the extension axis 12)
has a length a, such that the ratio of length a to width W (a:W) is preferably less than 5:1, more preferably less than 3:1 (fluid pressure, temperature and Fluctuations due to kinematic and viscous effects (such as changes in humidity) must be minimized as much as possible.

As previously mentioned, any of the embodiments of the invention described herein may be utilized as a stand-up aerodynamic profile (as shown in FIG. 3A) or as a stand-up aerodynamic profile (as shown in FIG.
(such as the pipe 34 shown in the front sectional view of Figure B) is incorporated into the flow path. Specifically for this flow path, although the flow path 34 in FIG. 3B is shown as a circular cross-sectional pipe of diameter D, many geometric configurations for the flow path 34 may be used. The generator plate 10 of FIG. 3B has a flow path blocking area equal to the product of its height h and width W. Unlike existing vortex generators used in suitable channel flow meters, the generator plate 10 in various embodiments according to the invention operates while blocking less than one-fifth of the cross-sectional area of the channel 34, and preferably ,
It operates while blocking 1/15 or less of the flow path 34.
Moreover, the generator plate 10 in various embodiments according to the invention reliably generates stable vortices over a wide range of flow velocities.

As mentioned above, the side surface 20 of the generator plate is aligned with the extension axis 1
2, but the rear portion 24 of the side surface 20 is sloped inwardly with respect to the rear edge 18 of the generator plate 10.
In this regard, the taper is very gradual as shown in the rear section 24h of FIG. 2B;
It is sharpened as shown by 4g.

4A and 4B show another embodiment of the invention, in which the side surface 20j of the generating plate 10j is the front edge 1.
6j and the trailing edge 18j. The generating member 36, preferably a wire, is attached to the front edge 16j of the generating plate 10j so as to extend upstream along the extension axis 12.
can be attached to. As shown in FIG. 4B, the generating member 36 is preferably arcuate so that it is attached to the leading edge 16j at two points. However, generating member 36 may include a substantially straight line segment and may have a variety of geometrical configurations.

A small depression 3 is formed on the leading edge 16j as shown in FIG. 4B.
8, the arcuate member 36 and the small depression 38 circumscribe the opening 26j, where the generating member 36 is the front opening edge and the small depression 38 is the rear opening edge.

In many respects, the embodiment shown in FIGS. 4A and 4B is similar to the previously described embodiments. For example, considering the length dimension L extending from the most upstream portion of the generating member to the trailing edge 18j, the above dimensional ratios also apply to the embodiments of FIGS. 4A and 4B. Further, for example, the leading edge 16j and the trailing edge 18j may be sloped in any manner described above.

Embodiments of the invention may advantageously utilize various types of sensors provided in many configurations. For example, FIGS. 5A and 5B show a generator plate 1 provided in a flow path 34 such that the extension axis 12 of the generator plate 10 is parallel to the fluid flow direction as indicated by an arrow 14.
Indicates 0. Although FIG. 5B shows a passageway 34 having a circular cross-section, the passageway 34 may be any suitable passageway.

The flow passage 34 shown in FIGS. 5A and 5B has a first passage wall 40 and a second passage wall 42, both parallel to the direction of fluid flow and facing each other. The first passage wall 40 has a transmitting transducer 44
is attached, and a receiving transducer 46 is attached to the second passage wall 42. The transducers 44, 46 are mounted on opposing passage walls such that the signal passing between them passes through the aperture 26 in the generator plate 10. The transmit transducer 44 and the receive transducer 46 are connected to appropriate electrical circuitry that determines the relative velocity of the fluid flow and the generator plate 10. In this regard, as an example of a suitable electrical circuit comparable to embodiments of the present invention, Joy et al.
No. 3680375 is cited here.

6A and 6B illustrate yet another embodiment of the invention in which a sensor 48 is attached to the rear opening edge 30 of the generator plate 10. Figure 7A and Figure 7
FIG. B shows how the sensor 50 is attached to a portion of the generator plate 10 between the rear opening edge 30 and the rear edge 18 of the generator plate 10. FIG.

Various sensor devices may be used as sensors in the embodiments of FIGS. 6 and 7. For example, sensors 48 and/or 50 may be hot wire devices or capacitor devices. Although the generator plate 10 in the embodiments of FIGS. 6 and 7 is shown positioned within the flow path 34, these embodiments may also have a erectable aerodynamic profile.

The embodiment shown in FIG. 1F is one of the features of each of the above embodiments.
It has a generator plate 10f that is a combination of two or more. Additionally, the embodiment of FIG. 1F has a surface discontinuity 52 on each side 20f. The characteristics of this surface discontinuity are
By Mahany et al. cited here.
U.S. Patent Application No. filed December 28, 1979
It is explained in No. 108066. Although the surface discontinuity 52 may take various forms such as a protruding portion or a raised portion, the surface discontinuity shown in FIG. 1F is a hole passing through the width W of the plate 10f.

In operation, each generator plate 10 according to various embodiments of the invention is oriented such that its axis of extension 12 is parallel to the direction of fluid flow indicated by arrow 14. When the fluid flows, Figure 2A, Figure 2B or Figure 2C
The essentially sharp leading edge 16 of the generator plate 10 having a profile according to any of the embodiments shown in the figures allows the plate 10 to
Avoid the formation of a significant ponding area on the upstream surface of the Therefore, the pressure changes associated with movement of the thinking zone are reduced, and their effect on the pressure gradients that affect vortex shedding is reduced.

After the fluid flows in a layer around the leading edge 22 of the side surface 20, the vortex (indicated at 54 in each figure) leaves the generator plate 10 at the aperture corner 32 that lies along the front aperture edge 28 of the aperture 26. do. The preferably sharp corners 32 of the front opening edge 28 allow for the formation of a well-shaped stabilizing vortex. When the vortex projects onto a plane perpendicular to the side surface 20 of the plate 10, it leaves the front opening edge 28 along an opening height that is preferably a length C shorter than the height b of the opening 26. Front opening edge 28
Since the tips of the tips are essentially continuous curves with no sharp discontinuities, the disturbances created at the tips are very small and vortices are generated only along the portion of the front opening edge 28 corresponding to the distance C.

After the vortex leaves the open corner 32, one or more sensors located on either of the contours detect the rate of vortex development. For example, Figures 5A and 5B
In the illustrated embodiment, transmit transducer 44 sends a signal, such as an acoustic signal, to vortex 54 near aperture 26 .
Receive transducer 46 receives the vortex modulated signal and uses this signal as an indication of the relative velocity of the fluid in the manner described in Joy et al., US Pat. No. 3,680,375. Various embodiments of the present invention may be utilized with many types of sensors in the aforementioned procedures, including sensors for velocity and/or flow measurement. In this regard, the sensor attached to the generator plate 10 may be a sensor that determines parameters other than the vortex generation rate.

A narrow, elongated generating plate generally produces laminar flow in the area near the open corner 32. The action of the portion of the generator plate 10 extending from the trailing opening edge 30 to the trailing edge 18 separates the two sides of the vortex array, thereby preventing the vortices from interacting after leaving. It is believed that the side surface 20 downstream from the trailing opening edge 30 dissipates the vortices due to viscous action, reducing the effect of the vortex array on the overall flow. This results in a reduced pressure drop across the generator plate 10 compared to conventional aperture objectives.

The rear portion 24 of the surface 20 is tilted to form the generator plate 10.
Reduce the size of the turbulent aperture after . this is,
There is a practical effect in reducing pressure drop and eliminating audible noise (such as whistling) that normally occurs at blunt terminations.

The operation of the embodiment shown in FIGS. 4A and 4B is very similar to that described above, except that generator member 36 is the most upstream portion of generator plate 10j. Therefore, the narrow generation member 36 does not generate a large thinking area, and forms a vortex train by quickly creating a vortex. Again, the sensor may be mounted in a variety of configurations, including the variant of FIG. 4B, i.e., the generator plate 10j may be mounted in a variety of ways (FIGS. 5A and 5B) such that the signal is transmitted through the vortex array near the aperture 26j. (in the procedure according to the example).

In the structure shown in FIG. 8, the side surface 2c of the generator plate 10
has at least one surface break or discontinuity 52. Although the surface break 52 may take various forms, such as a protrusion (i.e., a protrusion or ridge) or a circular hole, the surface break 52 shown in FIG. 8 is a radial slot in the side surface 20. In this exemplary embodiment, the radial slot is
It is formed on the side surface 20 so that its larger diameter is parallel to the direction of fluid flow. According to one exemplary configuration of the structure shown in FIG.
0.5 inch and the length dimension is 1.5 inch.

For the above, the surface break-up, such as a hole or slot, passes completely through the recess in the side surface 20 or the width of the generator plate 10, as shown in FIG. Furthermore, these surface splits are preferably arranged symmetrically with respect to the opening 26.

The device of Figure 10 is similar in structure to Figures 4A and 4B. Here again, the generation plate 10j is on its side surface 2.
It has at least one surface split or discontinuity 52 at 0j. As in the device of FIG. 8 above, the surface split portion 52 can be of several types. In this regard, FIG. 10 also shows the surface splits as radial slots.

In operation, a boundary layer appears along the side surface 20 of the generator plate 10 from the leading edge 16 to the trailing edge 18.

Further, within the surface split portion 52 of the present invention, the side surface 20
Depending on the Reynolds number for each point along the boundary layer, the boundary layer can be layered, transitional, or disordered. A wholly laminar or wholly disordered boundary layer does not adversely affect the vortex array produced by the open corner 32 or generating member 36. However, if a boundary layer transition zone occurs along the side surface 20, the frictional resistance will have a detrimental and unexpected impact on the fluid flow rate.

The surface discontinuities or surface break-ups 52 on the sides 20 of the generator plate 10 create boundary layer disturbances that eliminate the formation of boundary layer transition zones and allow the flow velocity shape to form without further disturbance. The surface discontinuities 52 are provided so that the boundary layer is not cut away from the generator plate to create the vortex sections in each embodiment.

The incorporation of 52 isosurface discontinuities results in a vortex generator capable of generating a stable vortex train over the range of fluid flow velocities of interest for a given flowmeter environment. Therefore, measurements from the generated vortices are highly accurate over a wide range of fluid flow rates.

Although the invention has been particularly shown and described with respect to preferred embodiments thereof, those skilled in the art will recognize that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Embodiments of the invention in which exclusive ownership or privilege is claimed are described below.