JP3029665B2 - Ring vortex flow meter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a ring vortex flowmeter, and more particularly, to a ring vortex flowmeter in which a plurality of concentric ring vortex generators having different diameters are arranged in a circular channel cross section. .

As is well known, a vortex flowmeter is provided with a vortex generator facing a flow in a flow path to be measured, detects a generated vortex, and detects a flow rate from the number of vortices generated per unit time. When the flow meter has a dimensional ratio between the vortex generator and the flow path within a predetermined range, a stable and strong vortex is generated, and the vortex frequency at this time is proportional to the ratio of the flow velocity to the representative length of the vortex generator. The Strouhal number, which is a proportional coefficient, is used as a constant within a predetermined Reynolds number range. However, looking at the situation of vortex generation, the vortices alternately separate from both sides of the vortex generator and flow out as vortices almost parallel to both sides of the vortex generator fixed at both ends to the wall in the flow path However, this vortex is a vortex tube having vortex ends that are open at both ends, and does not have a shape that is closed at both ends.

Furthermore, the vortex generator is a columnar body, and the flow in the flow path in the longitudinal direction with respect to the vortex generator of the columnar body has a non-uniform flow distribution, and the vortex becomes columnar only under predetermined conditions and separates.

The vortex flow meter having the ordinary columnar vortex generator has the above-mentioned problems. However, in order to make the vortex yarn a stable closed curve, the vortex generator is formed into a ring, and the ring vortex generator is used. A ring vortex flowmeter in which the body is arranged concentrically in a circular channel has been proposed.

As a known document relating to the present invention, there is JP-A-58-77620 (Kalman vortex flowmeter), which was proposed by one of the present inventors. In this flowmeter, a cone-shaped central structure is disposed on a central axis of a flow path formed of a circular pipe, and is supported in the flow path by a vane-shaped support structure. Is concentrically supported.

Since the above-mentioned ring vortex flow meter has a ring-shaped vortex generator (hereinafter referred to as a ring vortex generator), the vortex flowing out of the ring vortex generator is closed, and the vortex instability factor There is no vortex end, and it has advantages such as being suitable for axisymmetric flow such as a pipe flow because of its axially symmetric shape.

Problems of the Prior Art As described above, in the ring vortex flowmeter, the ring-shaped vortex generator is disposed at the center of the circular pipe flow path. And the vortex is closed, so that a stable ring vortex can be obtained.However, the vortex intensity is not always sufficient, and turbulent components in the fluid are mixed, and the frequency spectrum of the vortex signal , The half width was not necessarily small.

Furthermore, since the ring vortex generator is supported by the plate-shaped vane in the annular flow path formed by the cone-shaped central structure and the circular pipe flow path, the flow axis in the flow path, There were problems such as being easily affected by the posture.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. In order to generate a more powerful and stable ring vortex, (1) concentric and different radii are formed in a flow path cross-sectional view of a circular flow path. A ring vortex flowmeter characterized by disposing a plurality of ring-shaped vortex generators and detecting a flow rate from the number of ring vortices flowing out of the plurality of ring vortex generators per unit time, further comprising: In (2) and (1), a plurality of ring vortex generators having different radii are provided on a plurality of support means fixed to an inner peripheral portion of the plate-shaped ring in (2) and (1). A rig vortex flowmeter characterized in that the rig vortex flowmeter is concentrically supported and integrally formed so as to be able to be interposed and sandwiched in an external flow path pipe, and in (3), (1) or (2), The cross section of the ring vortex generator has a similar shape, and the cross section has a side facing the flow, and the length of the side is 3. The ring vortex flowmeter according to claim 1 or 2, wherein a plurality of the vortex flowmeters have a trapezoidal shape decreasing toward the downstream side. The ring vortex generator has two trapezoidal shapes, such as a peripheral shape having a length of B, and the side of the ring vortex generator having a cross section flowing therethrough. The distance between the ring vortex generator and the inner circumference of the plate-shaped ring is equal to G, and the distance between the inner ring vortex generator and the center axis of the ring is r. 4. The ring vortex flowmeter according to claim 1, 2 or 3, further comprising (2) two or more ring vortex generators in (1) or (2). The cross sections of the vortex generators are circles having the same diameter D, and the distance between the ring vortex generators and the distance between the outer ring vortex generator and the inner circumference of the plate-shaped ring are equal intervals G, and the inner ring The distance between the vortex generator and the central axis of the plate-shaped ring is represented by r. The object of the present invention is to provide a ring vortex flowmeter characterized by the following.

Embodiment FIGS. 1 (a), 1 (b) and 1 (c) are views showing a configuration for explaining an embodiment of a ring vortex flowmeter according to the present invention, and FIG. 1 (a) is a line YY FIG. 2B is a plan view seen from the upstream side (arrow Q), and FIG. 2C is a plan view seen from the downstream side. In the figure, 1 is a plate-shaped ring, 1a is a ring channel, 1b
Is a bolt hole, 2 is an outer ring vortex generator, 3 is an inner ring vortex generator, 4 is a support plate, 1a is a concave portion, 5 is a holding plate, 5a is a convex portion, and 6 is a screw.

In the drawing, the outer ring vortex generator 2 and the inner ring vortex generator 3 are rings having different diameters, and are arranged in the plate-shaped ring 1 with the axis OO as a common axis. A plurality of support plates 4 are for supporting and fixing the outer ring vortex generator 2 and the inner ring vortex generator 3 in the above-described arrangement, and one end is fixed to the plate-like ring 1. Are radially arranged toward the axis OO, and the other end is a free end. The outer ring vortex generator 2 and the inner ring vortex generator 3 are fitted into recesses of the support plate 4 and fixed by the holding plate 5. The pressing plate 5 is provided with a convex portion 5a, and the convex portion 5a presses the outer and inner ring vortex generators 2, 3 in the concave portion on the downstream side of the concave portion.
It is fixed with screws 6, but in order to stably press and fix
It is preferable to use an elastic material for 5a. The plate-shaped ring 1 is screwed into a pipe flange (not shown) at a bolt hole 1b to form a digital orifice.

The outer and inner ring vortex generators 2 and 3 are the main parts that generate ring vortices, respectively.The cross-section shown in the figure has a side facing the flow, and the length of the side becomes smaller on the downstream side and the flow is reduced. It has a trapezoidal shape symmetric to the direction. Note that the trapezoid includes a triangle, and the side is not necessarily a straight line.

Each ring vortex generator with a trapezoidal cross section generates a strong ring vortex stably even when used alone, but the cost of manufacturing is high. Can be used as a vortex flowmeter.

2 (a) and 2 (b) are diagrams showing a flow pattern of ring vortex generation of the ring vortex flowmeter of the present invention, and FIG. 2 (a) is a diagram showing a flow pattern of ring vortex generation of the same phase. (B) is a diagram showing the flow pattern of ring vortex generation in antiphase, where 2a is the outer edge of the outer ring vortex generator, 2b is the inner edge of the outer ring vortex generator, and 3a is the inner ring vortex generation. The outer edge of the body, 3b, is the inner edge of the inner ring vortex generator, and the parts which have the same effect as in FIG. 1 are given the same reference numbers.

In the drawing, the plate-like ring 1 represents only the upper half of the axis OO, and accordingly, the outer and inner ring vortex generators 2, 3 also show only the upper cross section. Assuming that the flow is a uniformly distributed flow in the direction of arrow Q, at a certain moment, in the flow pattern of ring vortex generation having the same phase as shown in FIG.
Ring vortex circulation gamma ₂ in clockwise is generated from the outer ring vortex shedder 2, ring vortex circulation gamma ₃ of clockwise flows out generated from the inner ring vortex generator 3 at the same time. Also, at the next moment, the ring vortex has a phase opposite to that of the ring vortex, that is,
Ring vortex of the circulating-gamma ₂ in the counterclockwise is generated from the outer ring vortex shedder 2, ring vortex circulation-gamma ₃ left around are generated from the inside of the ring vortex generator 3. This is sequentially repeated to emit rings in phase. When a vortex is generated in the same phase from the outer ring vortex generator 2 and the inner ring vortex generator 3, the inner edge 2 b of the outer ring vortex generator 2 and the outer edge 3 a of the inner ring vortex generator 3 are formed. The ring vortices generated from the portions are synchronized in frequency to be in a resonance state, and both the outer ring vortex generator 2 and the inner ring vortex generator 3 generate stable strong ring vortices.

In the flow pattern of the ring vortex generation of the opposite phase in FIG.
Γ _Two ring vortices are generated, and at the same time, the inner ring vortex generator 3
Generates a ring vortex in circulation # ₃ clockwise. As described above, the ring vortices generated from the outer ring vortex generator 2 and the inner ring vortex generator 3 flow out in opposite phases to each other, but also in this case, the circulation generated at the inner edge 2b of the inner ring vortex generator 2 a ring vortex-gamma _2, ring vortex generated from the portion of the outer edge 3a of the inner ring vortex generator 3 generates a stable strong ring vortex was become a resonant state where the vortex frequency are synchronized.

FIG. 3 is a view showing the arrangement of a ring vortex flowmeter according to the present invention. In the drawing, the parts which operate in the same manner as in FIG. 2 are denoted by the same reference numerals.

As described above, in the ring vortex flowmeter of the present invention, the outer ring vortex generator 2 and the inner ring vortex generator 3 generate mutually corrected strong ring vortices. There is an optimum range between the distance and the flow path wall of the annular flow path 1a.If they are too close to each other, no ring vortex will be generated, and if they are too close to the wall of the annular flow path 1a, the vortex strength will be affected by the wall surface. Decay. According to the experimental results of the present inventors, 1) The distance G between the wall surface of the annular flow path 1a and the outer ring vortex generator 2 and the distance between the outer ring vortex generator 2 and the inner ring vortex generator 3 are equal to each other. 2) The width of the outer and inner ring vortex generators 2, 3 is B, 3) the distance between the edge 3b of the inner ring vortex generator and the axis OO is r, 4) the radius of the annular flow path 1a is R. Under the condition of R = 2G + 2B + r (1) obtained, The best stable and strong ring vortex is generated in the range of
Particularly, it was remarkable in a low Reynolds number region.

FIG. 4 is a view showing an arrangement for explaining another embodiment of the present invention. In the figure, reference numeral 7 denotes an outer ring vortex generator, 8 denotes an inner ring vortex generator, and Have the same reference numerals as in FIG. In the figure, the outer and inner ring vortex generators 7, 8 are annular rings having circular cross sections, and as described above, the annular rings having circular cross sections are easy to manufacture and inexpensive.

Also in this case, there is a condition for stable generation of the ring vortex, and the diameter of the outer and inner ring vortex generators 7 and 8 is set as a representative length D, and R = 2G + 2D + r (3) Under the conditions of A strong ring vortex is generated in a stable range.

In the above description, the ring vortex generator has been described with respect to the outer and inner double rings, but a plurality of annular rings having different diameters may be arranged on a plane perpendicular to the flow,
Ring vortices generated from opposing edges of each of the ring vortex generators configured as described above become resonant and stable ring vortices having the same vortex frequency. can get.

Effects As is clear from the above description, the ring vortex flowmeter of the present invention has the following effects.

(1) A ring vortex generator concentrically arranged on the same surface generates a mutually compensated ring vortex, so that the ring is more stable and powerful than the conventional ring vortex flowmeter which is single-arranged. A vortex is generated, and the flow rate range is widened, and the characteristics particularly in the low Reynolds number range are improved.

(2) Since the ring vortex generator is housed in the plate-shaped ring with a width smaller than the thickness in the plate-shaped ring, the shape is simple, the ring vortex generator can be interposed between pipe flanges, and the flow rate range is wide. It can be a digital orifice.

(3) Since there is no component that affects the flow component, a flow meter with little installation effect can be provided.

[Brief description of the drawings]

FIG. 1 is a view showing a configuration for explaining one embodiment of a ring vortex flowmeter of the present invention, FIG. 1 (a) is a sectional view taken along the line YY,
FIG. 2 (b) is a plan view from the upstream side, FIG. 2 (c) is a plan view from the downstream side, and FIGS. 2 (a) and 2 (b) show a flow pattern of ring vortex generation of the ring vortex flowmeter of the present invention. FIG. 3A is a diagram showing a flow pattern of ring vortex generation in the same phase, FIG. 3B is a diagram showing a flow pattern of ring vortex generation in the opposite phase, and FIG. 3 is a diagram illustrating an embodiment of the present invention. FIG. 4 is a view for explaining another embodiment of the present invention. 1 ... plate-shaped ring, 2 ... outer ring vortex generator, 3 ... inner ring vortex generator, 4 ... support plate, 5 ... holding plate.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01F 1/32

Claims (5)

(57) [Claims] A plurality of concentric ring vortex generators having different radii are arranged in a cross section of a flow path having a circular cross section, and a ring vortex flowing out of the even number of ring vortex generators per unit time. A ring vortex flowmeter, characterized by detecting a flow rate from the number of vortices. 2. A flow path having a circular cross section is a plate-like ring, and a plurality of ring vortex generators having different radii are concentrically supported by a plurality of support means fixed to the inner periphery of the plate-like ring. 2. The structure as claimed in claim 1, wherein said outer passage tube is integrally formed so as to be interposed therebetween.
The described ring vortex flowmeter. 3. A cross section of the plurality of ring vortex generators is similar to the above, and the cross section has a side facing the flow,
3. The ring vortex flowmeter according to claim 1, wherein the side has a trapezoidal shape in which the length of the side decreases toward the downstream side. 4. A plurality of ring vortex generators as described above, wherein the cross-sectional shape of the ring vortex generators is a trapezoidal shape having the same shape as the side facing the flow having a length B, and each ring has a shape. The distance between the vortex generators and the distance between the outer ring vortex generator and the inner circumference of the plate-shaped ring are equal to G, and the distance between the inner ring vortex generator and the center axis of the ring is r. The ring vortex flowmeter according to claim 1, 2 or 3, wherein: 5. A plurality of ring vortex generators in the above, wherein the cross section of the vortex generators is a circle of the same diameter D, the interval between each ring vortex generator and the outer ring vortex generator. The interval to the inner circumference of the plate-shaped ring is equal to G, the interval between the inner ring vortex generator and the center axis of the plate-shaped ring is r, The ring vortex flowmeter according to claim 1 or 2, wherein: