JP3347978B2 - Underwater vortex prevention device for closed pump suction tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is generally used in large pump stations, etc., and prevents underwater eddies in closed pump suction water tanks in which generation of underwater eddies is prevented even when the flow velocity near the pump suction port is high. It is about.

[0002]

2. Description of the Related Art Generally, an open pit type suction water tank having a free water surface is used in a medium-sized pumping station, and a closed type suction water tank having no free water surface is generally used in a large pumping station. The flow path of this closed type suction water tank is such that an appropriate flow rate change is given to the inflow water and introduced into the pump.
Appropriate cross section changes are given. 6A and 6B show an example of a conventional closed suction water tank, in which FIG. 6A is a front view in which a side wall of the water tank is cut away, and FIG. 6B is a cross-sectional view of FIG.

In FIG. 6, a suction water tank 10 is provided with a partition wall 12.
Thus, two flow passages 14a and 14b are provided, and the partition wall 12 is cut off at the end thereof to form one flow passage, and a pump suction port 16 is provided vertically upward. The pump suction port 16 is provided with a pump impeller 18 of the pump. The downstream side of the pump suction port 16 of the suction water tank 10 is closed by a water tank side wall 10b. Further, the bottom surface 10a of the water tank 10 of the suction water tank 10 facing the pump suction port 16.
Further, a projection 20 whose horizontal cross-sectional area gradually decreases toward the pump suction port 16 is provided. This protrusion 2
One example of 0 is formed of two truncated cones and one cone stacked coaxially as shown in FIG.

The projections 20 allow the flow paths 14a, 14a
The flowing water from b is rectified and directed to the pump suction port 16 to prevent the occurrence of underwater vortex.

[0005]

In recent years, in a drainage station constructed near a big city, the amount of wastewater handled tends to increase. Therefore, if the size of the suction water tank 10 is increased in accordance with an increase in the amount of drainage, there is a problem that the space required for the construction is widened, the depth is increased, and the construction cost is increased. As one of the techniques for solving such a problem, it has been considered to increase the processing capacity without increasing the size by increasing the speed of flowing water in the suction water tank 10. However, when the flow velocity is increased, the drift and swirling flow due to the water tank side wall 10b provided downstream in the vicinity of the pump suction port 16 become strong, and the strong swirling flow causes a problem that the underwater vortex 22 is easily generated. For example, when the flow velocity V1 near the pump suction port 16 is less than 1.3 m / s, no underwater vortex is generated, but when it becomes 1.3 m / s or more,
As shown in FIG. 6A, the occurrence of a water vortex 22 is observed. When the underwater vortex 22 is generated, the pump generates vibrations and noises, which causes a problem that the pump operation is seriously hindered.

The present invention has been made in view of the circumstances of the prior art described above, and provides an underwater eddy prevention device for a closed type pump suction water tank in which underwater eddies are not generated even when the running water speed is increased, and a control method therefor. The purpose is to do.

[0007]

The underwater eddy prevention device for a closed pump suction water tank according to the present invention has been made in order to achieve the above-mentioned object, and is provided from the bottom of the water tank facing the vertical pump suction port. A projection having a horizontal sectional area gradually reduced toward the pump suction port is provided. The opening angle is symmetrical with respect to the flow direction of the suction water tank when viewed from a plane, and the opening angle toward the downstream side is in a range of 30 ° to 100 °. Two surfaces are protruded from the protrusion so as to face a swirling flow by a water tank side wall on the downstream side of the protrusion, and the two surfaces are provided on a bottom outer peripheral edge of the protrusion or on the bottom surface of the water tank. It is configured to abut.

[0008] The ridges of the two surfaces that do not contact the protrusion may be formed as oblique sides connecting the apex of the protrusion and the outer peripheral edge of the bottom or the bottom of the water tank.

[0009] The ridges of the two surfaces that do not contact the protrusion may be constituted by a horizontal side and a vertical side connecting the apex of the protrusion and the outer peripheral edge of the bottom or the bottom of the water tank.

Further, the two flat members are substantially symmetrical with respect to the flow direction from the projection and viewed from a plane with respect to the flow direction, and the opening angle is in the range of 30 ° to 100 ° toward the downstream side. It may be arranged vertically in a V-shape.

Further, the two surfaces are substantially V-shaped and are symmetrical with respect to the flow direction from the projections when viewed from a plane, and have an opening angle in the range of 30 ° to 100 ° toward the downstream side. It is also possible to arrange and arrange members.

[0012]

FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 shows a first embodiment of an underwater eddy prevention device for a closed pump suction water tank of the present invention,
(A) is a front view in which the side wall of the water tank is cut away, and (b) is a cross-sectional view taken along the line BB of (a). In FIG. 1, FIG.
The same or equivalent members are denoted by the same reference numerals, and duplicate description will be omitted.

FIG. 1 differs from FIG. 6 in that
As shown in FIG. 1B, two flat plates are symmetrical with respect to the flow direction of the suction water tank 10 from the vertical center axis of the projection 20 and open at an angle of 45 ° toward the downstream side as viewed from above. The members 30a and 30b have a substantially V-shape and are arranged so as to face the swirling flow of the water tank side wall 10b. Each of the flat plate members 30a and 30b has a substantially triangular shape having a ridge abutting on and fixed to the peripheral surface of the projection 20, and an oblique ridge connecting the apex of the projection 20 and the bottom peripheral edge or the water tank bottom surface 10a. Yes, it is arranged to be vertical.

When a test was conducted in such a configuration,
When the flow velocity V1 near the pump suction port 16 was 2 m / s or less, it was confirmed that no underwater vortex was generated. Protrusion 20
It is considered that the swirling flow due to the water tank side wall 10b provided in the vicinity of the downstream side is suppressed or prevented by the substantially V-shaped flat plate members 30a, 30b, and as a result, the generation of the underwater vortex 22 is prevented. . Therefore, according to the present invention, the maximum flow velocity V1 can be increased to 2 m / s, whereas the maximum flow velocity V1 for preventing generation of the underwater vortex was 1.3 m / s or less. Thus, it has about 1.5 times the processing capacity.

Further, as shown in FIG. 2, the present inventors conducted a test in a second embodiment in which the shape of the flat plate member was substantially square. Here, FIG. 2 shows a second embodiment of the underwater eddy prevention device for the closed pump suction water tank of the present invention, wherein (a) is a front view in which the side wall of the water tank is cut away, and (b) is (a). C-
It is C sectional arrow view. In FIG. 2, the flat plate members 32a,
32b is a ridge abutting and fixed on the peripheral surface of the projection 20;
It is a substantially square shape having a square-shaped ridge formed by a horizontal side and a vertical side connecting a with each other, and its opening angle is about 45 ° with respect to the flow so as to form a vertical plane.

In a test using such a configuration, it was confirmed that no underwater vortex was generated if the flow velocity V1 near the pump suction port 16 was 2 m / s or less, as in the first embodiment shown in FIG. .

Further, the present inventors carried out experiments by changing the opening angles of the two flat plate members 30a and 30b shown in FIG. 1 and the opening angles of the two flat plate members 32a and 32b shown in FIG. It is clear from the superposition that underwater flow velocity V1 near the pump suction port 16 is 2 m / s or less, and if these opening angles are in the range of 30 ° to 100 °, no underwater vortex is generated. Was.

By the way, the present inventors set the opening angle of the plate members 30a and 30b in the embodiment shown in FIG.
As ゜, experiments were carried out by disposing them orthogonally to the flow direction as shown in FIG. 3 and disposing them parallel to the flow direction as shown in FIG. In any of FIGS. 3 and 4, when the flow velocity V1 was 1.3 m / s or more, generation of the underwater vortex 22 was confirmed, and the structure was unable to prevent the generation of the underwater vortex 22.

Further, the present inventors, as shown in FIG.
The test was performed in the third embodiment using one substantially V-shaped member instead of the two flat plate members in the embodiment. Here, FIG. 5 shows a third embodiment of a submersible eddy prevention device for a closed pump suction water tank of the present invention, wherein FIG. 5 (a) is a front view of the water tank side wall cut away, and FIG. 5 (b) is (a). It is an FF sectional view seen from the arrow. In FIG. 3, one V-shaped member that is symmetrical with respect to the flow direction of the suction water tank 10 from the protrusion 20 as viewed from a plane as shown in FIG. 3
4 are provided. The V-shaped one member 34 is provided so as to face the swirling flow generated by the underwater side wall 10b and to be perpendicular to the surface.

[0020] Even in the test in such a configuration, FIG.
As in the case of the first embodiment shown in FIG. 5, it was confirmed that no underwater vortex was generated when the flow velocity V1 near the pump suction port 16 was 2 m / s or less.

[0021]

As described above, the underwater eddy prevention device for the closed pump suction water tank according to the present invention is constructed, so that the following special effects can be obtained.

According to the first aspect of the present invention, there is provided an apparatus for preventing underwater vortex of a closed pump suction water tank, wherein the opening angle of the suction pump is 30 ° to 100 ° which is symmetrical with respect to the flow direction of the suction water tank when viewed from above and viewed downstream. Since the two surfaces protrude from the protrusion provided on the bottom surface of the water tank in the range of ゜, and these two surfaces are disposed so as to abut on the outer peripheral edge of the bottom of the protrusion or the bottom surface of the water tank, the protrusion is provided. The swirling flow due to the water tank side wall on the downstream side can be suppressed in two planes having an opening angle of 30 ° to 100 °,
Even if the flow velocity is increased so much, no underwater vortex is generated due to the swirling flow. Therefore, by setting the flow velocity high, the processing flow rate can be increased without increasing the size of the closed pump suction water tank. Thus, an increase in installation space and construction costs can be suppressed.

According to a fourth aspect of the present invention, there is provided an underwater eddy prevention device for a closed pump suction water tank, wherein two vertical surfaces for suppressing the generation of underwater vortices are formed into a substantially V-shaped two plate member. Since it is arranged and configured, its structure is relatively simple. In addition, the existing suction water tank can be easily modified.

Further, in the underwater eddy prevention device for the closed pump suction water tank according to the fifth aspect, since one V-shaped member is provided downstream of the projection, the strength of the projection is reduced accordingly. The structure becomes robust and can easily obtain a structure that can sufficiently withstand the water pressure caused by the high-speed running water.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a submersible eddy prevention device for a closed pump suction water tank according to the present invention, wherein FIG. 1 (a) is a front view in which a side wall of the water tank is cut away, and FIG. FIG.

FIGS. 2A and 2B show a second embodiment of the underwater eddy prevention device for a closed pump suction water tank of the present invention, wherein FIG. 2A is a front view in which the side wall of the water tank is cut away, and FIG. It is C sectional arrow view.

3A and 3B show an example of an experiment of an underwater vortex prevention device for a closed-type pump suction water tank, wherein FIG. 3A is a front view in which a side wall of the water tank is cut away, and FIG. 3B is a sectional view taken along the line DD of FIG. FIG.

4A and 4B show another example of the experiment of the underwater eddy prevention device for the closed pump suction water tank, wherein FIG. 4A is a front view of the water tank with a side wall cut away, and FIG. 4B is an EE cross section of FIG. It is an arrow view.

5A and 5B show a third embodiment of the underwater eddy prevention device for a closed pump suction water tank according to the present invention, wherein FIG. 5A is a front view of the water tank with its side wall cut away, and FIG. It is an F sectional view.

6A and 6B show an example of a conventional underwater eddy prevention device for a closed pump suction water tank, wherein FIG. 6A is a front view in which a side wall of the water tank is cut away, and FIG. 6B is a sectional view taken along line AA of FIG. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Suction water tank 10a Water tank bottom face 10b Water tank side wall 16 Pump suction port 20 Projection 30a, 30b, 32a, 32b Plate member 34 One V-shaped member

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-308400 (JP, A) JP-A-55-123398 (JP, A) JP-A-63-183397 (JP, U) JP-A-52-1 92404 (JP, U) Fully open 1984-58,798 (JP, U) Fully open, 58-167704 (JP, U) Fully open, 58-130784 (JP, U) Fully open, 63-183398 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) F04D 29/66 F04D 29/54 F04D 13/00 F04D 13/16 F15D 1/12

Claims (5)

(57) [Claims] 1. A projection whose horizontal cross-sectional area gradually decreases from a bottom surface of a water tank facing a vertical pump suction port toward the pump suction port, and which is symmetrical when viewed from a plane with respect to a flow direction of the suction water tank. And the opening angle toward the downstream side is 30
In the range of {100}, two surfaces are protruded from the protrusion so as to face the swirling flow of the water tank side wall on the downstream side of the protrusion, and the two surfaces are outside the bottom of the protrusion. An underwater eddy prevention device for a closed pump suction water tank, wherein the apparatus is configured to abut on a peripheral portion or the bottom of the water tank. 2. The underwater eddy prevention device for a closed pump suction water tank according to claim 1, wherein a ridge not contacting the projection on the two surfaces is a vertex of the projection and a bottom outer peripheral edge or the water tank. An underwater eddy prevention device for a pump suction tank, which is a hypotenuse connecting a bottom surface. 3. The underwater eddy prevention device for a closed pump suction water tank according to claim 1, wherein a ridge not contacting the protrusion on the two surfaces is a vertex of the protrusion and a bottom peripheral edge or the water tank. An underwater eddy prevention device for a pump suction tank, comprising a horizontal side and a vertical side connecting a bottom surface. 4. The underwater eddy prevention device for a closed-type pump suction water tank according to claim 1, wherein the two surfaces are symmetrical with respect to the flow direction from the projection and open to the downstream side with respect to a plane. An underwater vortex prevention device for a pump suction tank, wherein two flat plate members are vertically arranged in a substantially V-shape in an angle range of 30 ° to 100 °. 5. The underwater eddy prevention device for a closed pump suction water tank according to claim 1, wherein the two surfaces are symmetrical with respect to the flow direction from the projection and open toward the downstream from the plane. Approximately V whose angle is in the range of 30 ° to 100 °
Submersible eddy prevention device for a pump suction tank characterized by comprising one member shaped like a letter