JPH0512345Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to a jet flow gate used in agricultural water transmission channels, etc., and is particularly concerned with jet flow gates that suppress the occurrence of unstable flow in the jet flow. Regarding gates.

<Conventional technology> Conventionally, jet flow gates have been installed in circular pipes for water supply connected to dams, etc., and can easily open and close high-pressure water using a sliding door body with a simple and robust structure. Due to its low vibration and cavitation, it is widely used as water intake and discharge equipment for agricultural water, industrial water supply, flood control, etc., and for regulating the flow rate of downstream rivers and waterways.

As shown in FIGS. 4 and 5, such a jet flow gate generally includes an expansion tube 2 connected to an upstream pipe line 1, and the downstream end of the expansion tube 2 has an inner side. A seal ring 30 is provided, which includes a ring base material 13 tapered at 45 degrees with respect to the water channel axis, and a nozzle 40 whose tip can be slightly displaced in the upstream and downstream directions. On the downstream side of the seal ring 30, a door body 50 that can be moved up and down has an inclined lip surface 50a.
A sharp lip edge 50b at the lowermost end is provided as an upstream end, and an energy reducing pipe 6 having an air supply pipe 7 is further provided. and nozzle 40
A sharp edge-shaped tip 40a is formed at the tip of the door 50, and is configured to prevent the high-speed jet stream released downstream from colliding with the door groove 16 of the door body 50. In addition, the energy reducing pipe 6
is provided to reduce the energy of the high-speed jet flow to normal flow so that it does not damage downstream structures.

<Problems to be solved by the invention> However, in a jet flow gate with such a conventional configuration, due to the high water pressure on the upstream side, the jet flow passing through the seal ring 30 suffers from an extreme contraction phenomenon. As a result, the entire area around the outer periphery of the vena contracta streamline 8 becomes negative pressure, and the flow condition becomes unstable as shown by the scattering streamline 8a, and a droplet flow 9 is generated at the vena contracta streamline 8 section. This droplet flow 9 will generate vibration and cavitation unless a large amount of air is sent through the air supply pipe 7.
Typically requires air at 80% or more of the flow rate. Therefore, the downstream deenergization pipe 6 of the door body 50 has a pipe cross section that is 1.8 times or more larger than that of the upstream pipe line 1. In addition, the viscosity of water mixed with air is low, and the friction and impact resistance between the water particles is small, so that the energy-reducing effect of the jet flow in the energy-reducing tube 6 is not sufficiently exerted. Therefore, the energy reducing pipe 6 becomes long, which, together with the above-mentioned increase in the cross-section of the pipe, becomes an uneconomical factor.

Furthermore, if the high-speed water flow contains wood chips, sand, gravel, etc., the tip 40a of the nozzle 40 may be damaged, and it cannot be used in waterways where dams accumulate sediment and require sand removal. There was a fatal problem.

<Means for solving the problem> This invention was made to solve the above problem, and consists of an expansion tube connected to the conduit and a tapered tube provided at the downstream end of the expansion tube. A jet flow gate comprising a seal ring and a door body provided vertically movably on the downstream side of the seal ring, wherein the seal ring is arranged on the downstream side so that its cross-sectional shape approaches asymptotically to the axis of the waterway. The jet is equipped with a curved part formed in a linear quadratic curve extending toward the waterway, and completes the flow contraction at this curved part, and discharges the jet flow in the axial direction of the waterway at the minimum cross section of the tip of the seal ring. It is a flow gate.

<Function> This device is constructed as described above, and the seal ring has a curved section whose cross-sectional shape is a quadratic curve that approximates the streamline of the jet flow, so that the streamline of the jet flow is approximately parallel to the waterway axis. As a result, negative pressure fluctuations in the droplet area are reduced.

As a result, the amount of air supplied also decreases, causing vibrations and
The occurrence of cavitation is suppressed.

<Example> Hereinafter, an example of this invention will be shown in Figures 1 to 3.
This will be explained based on the diagram.

Fig. 1 is an enlarged cross-sectional view of the seal ring that forms the main part of this invention, Fig. 2 is a longitudinal cross-sectional view showing a jet flow gate equipped with the seal ring, and Fig. 3 is a curved section of the seal ring. FIG. In addition, in the following, the parts that are the same as the conventional example are as follows.
The same reference numerals are used to omit the explanation.

In the figure, 3 is a seal ring consisting of a ring base material 13, a nozzle 4, etc., and a door body 5 that is vertically movable is provided on the downstream side of the seal ring 3. The nozzle 4 has a flange-like flange portion 4a.
and a vertical sealing surface 4b that comes into sliding contact with the skin plate 5b of the door body 5 and slightly protrudes from the back surface 4f.
It has a tapered portion 4c, a curved portion 4d, and a straight portion 4e that are in contact with the flow. The tapered part 4c forms an extension surface F of the tapered part of the ring base material 13, has an angle of 45 degrees with respect to the axis of the water channel axis, and has a curved part 4.
As will be described later, d is continuous with the tapered part 4c and is formed so as to approach the axis toward the downstream side, and further continues with a slight straight part 4.
e is formed.

The formation of the cross-sectional linear shape of the curved portion 4d is as shown in FIG.
is aligned with the extension line E of the back surface portion 4f, and the tapered portion 4
Extension line F extending from c in a direction intersecting extension line E
Let the point of contact between and the virtual ellipse A be the starting point H. Also,
The intersection of the extension line E and the lower outer periphery of the imaginary ellipse A is defined as an end point J, and a curved portion 4d along the outer periphery of the imaginary ellipse A is formed between the start point H and the end point J. Then, the straight part 4 continues tangentially with the tapered part 4c at the starting point H, and is parallel to the axis of the water channel axis at the ending point J.
Continued with e.

The seal ring 3 formed in this way has an O-ring 10 interposed between the ring base material 13 and the nozzle 4, and a bolt is inserted into a screw hole provided in the ring base material 13 via a retainer ring 11. 12 allows the nozzle 4 to be attached and detached. Note that 13a shown in FIG. 1 is a stopper portion of the ring base material 13.

The door body 5 has a lower end lip portion 5a formed on its lower surface, which has a cross section similar to the curved portion 4d of the nozzle 4 and bulges out in a quadratic curve toward the downstream side. Further, a skin plate 5b made of SUS304 or the like is attached to the upstream side surface of the door body 5 and the surface of the lower end lip portion 5a.

According to the jet flow gate equipped with this seal ring 3, as shown in FIG.
As a result, the direction of the jet flow is directed in the direction of the channel axis, and the flow condition of the jet flow is stabilized, resulting in a droplet flow 9.
The occurrence of is suppressed.

In a model experiment, when the jet flow velocity was 25 m/s, the amount of air mixed into the jet flow was approximately 40% due to the suppression effect of the droplet flow 9, reducing the amount of air mixed in to 1/2 compared to the conventional example. was confirmed.

Moreover, the quadratic curve shape of the lower end lip portion 5a of the door body 5 makes it possible to stabilize the flow condition downstream of the gate during opening and closing of the door body 5.

It should be noted that this invention is not limited to the above-mentioned explanation and illustrations, and its embodiments can be changed within a range that does not depart from the technical idea of this invention. For example, the nozzle 4 may have the straight portion 4e omitted. In that case, the curved part 4
The end point J of d is located at the corner that intersects with the sealing surface 4d.

Further, the curvature and curve length of the curved portion 4d are not defined by fixed numerical values, but may be a quadratic curve of acceleration changes depending on the flow velocity of the waterway, etc.

<Effects of the invention> With this invention, the jet flow gate has the above-mentioned hydraulic configuration and has greatly improved the drawbacks of the conventional example. In other words, the tip of the seal ring, which serves as the opening of the jet flow gate, is equipped with a quadratic linear curved section that approximately matches the contraction streamline of the jet flow. Pressure fluctuations are small and the flow condition of the jet flow is stabilized. Therefore, the streamlines after discharge are stabilized in the axial direction of the waterway, which reduces vibration and cavitation during opening and closing. Furthermore, the generation of droplet flow is suppressed, and the amount of air mixed into the jet flow is halved.

Therefore, the diameter and length of the energy reducing tube of the jet flow gate can be reduced, construction costs can be reduced, and a large economic effect can be achieved. Furthermore, since the amount of air supplied is small, the jet flow gate can be easily installed underwater, and its range of applications as an underwater discharge gate can be expanded.

In addition, since the tip of the seal ring is aligned with the contractile streamline, even if wood chips, sand, gravel, etc. are included in the high-speed water flow, they will flow down along the curved part and close to the seal ring. This has the effect of preventing damage, enabling mud removal from the dam, and extending the life of the dam.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view of a seal ring portion that forms the main part of a jet flow gate according to an embodiment of this invention.
Fig. 2 is a longitudinal sectional view of the jet flow gate, Fig. 3 is an explanatory diagram of the curved part of the seal ring, Fig. 4 is a longitudinal sectional view of the conventional jet flow gate, and Fig. 5 is the conventional seal. It is an enlarged sectional view of a ring part. 2... Expansion tube, 3... Seal ring, 4... Nozzle, 4c... Tapered part, 4d... Curved part, 5
... Door body, 5a ... Lower end lip part, 6 ... Energy reduction pipe.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) An expansion tube connected to a conduit, a tapered seal ring provided at the downstream end of the expansion tube, and a tapered seal ring provided downstream of the seal ring so as to be movable up and down. A jet flow gate is provided with a gate body, and the seal ring has a cross-sectional shape formed in a linear quadratic curve extending downstream so that the cross-sectional shape approaches the axis of the waterway. A jet flow gate characterized by comprising: (2) A seal ring with a linear curved part in the shape of a quadratic curve extending downstream so that the cross-sectional shape asymptotically approaches the axis of the waterway; The jet flow gate according to claim 1, which is a registered utility model, and further comprises a door body having a lower end lip portion formed in a linearly bulging manner.