JP2015140515A - movable weir - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a movable weir capable of preventing the occurrence of a water drop, and capable of relieving an upstream side water level variation by a flow rate variation, by automatically adjusting opening of a weir body, while holding an upstream side water level by resistance of a weir body of a submerged weir type.SOLUTION: The movable weir is interposed in a water passage, and includes at least the weir body and a set of support links for forming an acute angle to the horizontal direction and having mutually the equal length in parallel. One end of the set of support links is respectively joined by a hinge to the weir body, and the other end of the set of the support links is respectively joined by a hinge to an immovable point.

Description

  More particularly, the present invention relates to a movable weir capable of maintaining a water level difference between an upstream side and a downstream side of a water channel substantially constant regardless of increase or decrease in flow rate. .

In a water discharge channel or the like of a power plant, it may be necessary to keep the upstream water level higher than the downstream water level (eg sea level).
In this case, it is common to install a resistor such as a weir in the water channel to ensure a difference in water level between the upstream side and the downstream side (hereinafter simply referred to as “water level difference”). As a result, the mixing of bubbles on the downstream side becomes a problem.

The methods for preventing the water surface foaming are roughly classified into the following two approaches.
(A) A method of reducing the amount of foaming while allowing water to fall.
(B) A method that does not cause the water falling phenomenon itself.
As inventions employing these methods, there are inventions described in the following patent documents.

  The water discharge pit described in Patent Document 1 corresponding to (a) has a perforated plate and a sill interposed between the upstream water tank and the downstream water tank to weaken the falling water and reduce the amount of bubbles generated. It is.

  As a method corresponding to the above (b), as in the water discharge facility described in Patent Document 2, a flap type gate is installed as a water level adjusting means at the water discharge port of the downstream water discharge channel, There is a method in which when a predetermined water level difference is exceeded, the gate is automatically opened by water pressure, and the upstream water level is adjusted by fluctuations in the opening of the gate. This is effective in that the resistance of the conventional diving weir is roughly proportional to the square of the flow velocity, so that the problem that the rising gradient of the upstream water level with respect to the increase in flow rate is high can be avoided.

  In addition, as another method corresponding to the above (b), there is a method of mechanically adjusting the flow rate by providing a movable valve in the water discharge channel.

JP 2001-004787 A JP 2001-329520 A

  However, the conventional method described above may have at least one of the following problems.

(1) Viewpoint of foam suppression function In the method according to Patent Document 1, it is only possible to reduce mixing of bubbles, and water surface foaming cannot be completely prevented.

(2) Viewpoint of water level adjustment function In the case of the method of installing a flap type gate as in Patent Document 2, although the amount of fluctuation in the water level is reduced, the force acting on the gate (upstream side) It is necessary to increase the water pressure. Therefore, as the flow rate increases, the difference in water level between the upstream side and the downstream side inevitably increases, and the wall height must be set according to the fluctuation range of the water level.
Therefore, it is desired to realize a method that can maintain a state where the water level difference between the upstream side and the downstream side is small even when the flow rate is increased.

(3) Viewpoint of maintenance and management When a movable valve is provided in the water discharge channel and the flow rate is adjusted mechanically, a method for controlling the opening degree by the flow rate and maintenance are required, and maintenance and labor are required.

  In other words, in the present invention, in suppressing the generation of bubbles due to falling water, the opening of the weir body is automatically adjusted while maintaining the water level on the upstream side by the resistance of the submerged weir body. An object of the present invention is to provide a movable weir capable of preventing generation and mitigating upstream water level fluctuations due to flow fluctuations.

  The invention of the present application to solve the above problems is a movable weir interposed in a water channel, and a weir body and a set of support links that form an acute angle with respect to the horizontal direction and are parallel to each other and are equal in length. The one end of the set of support links is hinge-coupled to the dam body, and the other end of the set of support links is hinge-coupled to the fixed point. .

  According to the present invention, at least one of the effects described below can be obtained.

(1) Viewpoint of foam suppression function Since the weir body automatically floats or sinks according to the difference in water level between the upstream side and the downstream side, the upstream water level does not exceed the top of the weir body.
Therefore, foaming due to falling water can be reliably prevented without increasing the height of the dam body more than necessary or providing an opening / closing mechanism such as a gate at the bottom.

(2) Viewpoint of water level adjustment function Unlike conventional methods, the fluctuation range of the difference in water level between the upstream side and the downstream side is small as the flow rate on the upstream side increases.
Therefore, a substantially predetermined water level difference can be maintained without being affected by the increase or decrease in the flow rate on the upstream side, which is advantageous for fluctuations in the water level in the upstream facility.

(3) From the viewpoint of maintainability Since the main body of the weir automatically floats or sinks according to the water level difference between the upstream side and the downstream side, maintenance of control mechanisms such as movable valves and flaps is required as in the conventional method. do not do.

The model figure which shows the movable weir of 1st Example which concerns on this invention. The model figure which shows the variable of the calculation formula which shows the operation | movement basis of a weir body. Schematic which shows the state transition (bottoming state) of the movable weir which concerns on this invention. Schematic which shows the state transition (floating state) of the movable weir which concerns on this invention. Schematic which shows the state transition (from a sedimentation to a stationary state) of the movable weir which concerns on this invention. The comparison figure which shows the fluctuation | variation of the water level difference with respect to increase / decrease in the flow volume in the movable weir etc. which concern on this invention. The model figure which shows the movable weir of 2nd Example which concerns on this invention.

  Hereinafter, embodiments of the movable weir according to the present invention will be described with reference to the drawings.

<1> Overall Configuration The movable weir according to the present invention mainly maintains the water level difference between the upstream side X and the downstream side Y of the water channel substantially constant by automatically changing the opening degree of the weir body according to the flow rate. The target structure.

In FIG. 1, the model figure which shows the movable weir of 1st Example which concerns on this invention is shown.
The movable dam A according to the present embodiment is provided in the water channel and includes at least a dam body 1 and a set of support links 2 that connect the dam body 1 so as to be movable up and down.
Details of each component will be described below.

<2> Weir body The weir body 1 is a member for holding a water level difference in the water channel by a resistance of the weir body as a so-called diving weir.
The weir body 1 adopts a known structure and shape, and detailed description thereof is omitted.

<3> A set of support links A set of support links 2 is a member for supporting the weir body.
From the viewpoint of stabilizing the posture of the dam body 1, the support links constituting the set of support links 2 require at least two when viewed from the side, but the number is not particularly limited and is appropriately determined in a desirable design aspect. be able to.
In the present embodiment, the set of support links 2 is composed of two support links (2a, 2b) in a side view.

<3.1> Arrangement of Support Links Each support link 2a, 2b has the same length and is arranged parallel to each other when viewed from the side.
Further, the support links 2a and 2b are arranged so as to maintain a state inclined at an acute angle with respect to the horizontal direction. More specifically, the dam body is inclined at an acute angle with respect to the horizontal direction in a state where the dam body is bottomed.
In this embodiment, the end portions 22 of the support links 2a and 2b are arranged on a virtual line (virtual vertical line 3a) drawn in a substantially vertical direction.

<3.2> Connection with Weir Body One end 21 of the pair of support links 2 is coupled to the weir body 1 via a rotation mechanism such as a hinge or a pin. In this embodiment, a hinge 41 is used.
What is necessary is just to determine a connection position with the dam main body 1 suitably on a design.

<3.3> Connection with Fixed Point The other end 22 of the pair of support links 2 is coupled to the fixed point 5 via the rotating mechanism. In this embodiment, a hinge 42 is used.
The fixed point 5 is used in the sense that the position of the point is fixed without moving, and is set to a side wall of a water channel (not shown), a member extending in the width direction or the front-rear direction of the water channel, and the like. Can do.

<3.4> Structure after Connection According to the above-described connection mode, the movable weir according to the present invention is a virtual vertical line 3a that connects between the pair of support links 2 and the ends of the pair of support links 2. And a parallelogram is formed in a side view with the plane of the dam body 1.
And since the edge part of each support link 2a, 2b is couple | bonded by the hinges 41 and 42, the above-mentioned parallelogram will exhibit the parallel crank mechanism Z which made the said virtual vertical line 3a look like a stationary node. .
With this parallel crank mechanism Z, the dam body 1 can be moved up and down while maintaining a vertical state, and an opening B can be formed between the dam body 1 and the bottom of the water channel.

<4> Calculation Example of Operation Principle Hereinafter, a calculation formula relating to the grounds on which the movable weir according to the present invention transitions to a floating operation or a subsidence operation due to a change in the water level difference is shown.

FIG. 2 is a model diagram showing variables used in the following calculation formula.
The weir body in this model diagram is assumed to be thin enough that buoyancy can be ignored for convenience of explanation.

<4.1> Relationship between water level difference and support link angle Assuming hydrostatic pressure as the water pressure, the following equation holds from the balance of forces in the vertical and horizontal directions and geometrical conditions.

Here, when F1 + F2 = F is set, equations (1) and (2) are

From equation (4)

Substituting into equation (5)

Substituting equation (3) into this,

以上、式（９）より、ｈ０を一定とした場合のθとΔｈの関係が導かれる。 And put

As described above, the relationship between θ and Δh when h0 is constant is derived from the equation (9).

<4.2> Relationship between water level difference and flow rate Next, ignoring the velocity head and assuming that the loss coefficient f is substantially constant, the following equation holds.

よって、式（１１）により、θ、Δｈに対するｑが求められる。 Substituting equation (3)

Therefore, q with respect to θ and Δh is obtained by the equation (11).

<5> Details of Operation Principle Details of the operation principle of the movable weir according to the present invention will be described with reference to the state transition diagrams shown in FIGS. 3A to 3C.

<5.1> No upstream flow rate (flow rate = 0)
FIG. 3A shows a state where the movable weir is bottomed and there is no upstream flow rate.
In FIG. 3A, (a) is a schematic view of a conventional flap-type dive weir, (b) is a schematic view of a movable weir according to the present invention, and (c) is a view in (a) and (b) above. It is a graph which shows the relationship between a flow volume and a water level difference.
The horizontal force due to the water level difference in each support link shown below will be described on the premise that the horizontal force is decomposed from the overall horizontal force due to factors such as the number of support links and mounting positions. The same applies to other values.

The movable weir A is in contact with the bottom surface of the water channel, and a model diagram of the force at the hinge at one end of a certain support link is indicated by P0 which is the resultant force of the horizontal force F0 due to the water level difference and the own weight Pd of the weir body. The angle of the resultant force P0 is θ0.
In this state, since the horizontal force F0 based on the water level difference is insufficient, the weir body 1 sinks due to its own weight Pd and remains grounded on the bottom surface of the water channel.

<5.2> Ascent start state (when flow rate = Q1)
FIG. 3B shows a state in which the flow rate is obtained on the upstream side and the movable weir starts to rise due to an increase in the water level difference.
When the upstream flow rate increases from the state where the water channel is blocked by the weir body 1, the upstream water level rises (h0 → h1), and the water level difference also increases (Δh0 → Δh1).
When the water level difference increases, the horizontal force due to the water pressure difference between the upstream side and the downstream side also increases (F0 → F1).
Due to the increase in the horizontal force, the angle θ1 of the resultant force P1 with the own weight Pd becomes smaller than the angle δ0 of the support links 2a and 2b.
Due to the resultant force P1, the pair of support links 2 starts to rotate counterclockwise in FIG. 3B from the time when a certain water level difference is reached, and the weir body 1 makes a transition in the direction of rising while maintaining the vertical state. It will be.

<5.3> Settling start state (flow rate = Q1)
FIG. 3C shows a state in which the movable weir starts to sink due to a decrease in the water level difference due to the rising of the weir body 1 (return of the water channel).
When the weir body 1 transitions to the floating side due to the increase in the water level difference described above, an opening is formed between the bottom surface of the water channel and the weir body 1, and the water that has been dammed on the upstream side starts to flow to the downstream side.
Due to this water flow, the upstream water level stops rising and begins to transition in a decreasing direction.
When the water level on the upstream side starts to decrease and the horizontal force starts to decrease (F1 → F1 ′ → F1 ″), the angle of the resultant force with the own weight Pd gradually increases.
With this resultant force, the pair of support links 2 rotate clockwise in FIG. 3C, and the weir body 1 transitions in the direction of sinking while maintaining the vertical state.

<5.4> Balanced state (flow rate = Q1)
Still referring to FIG.
When the lowering of the water level on the upstream side and the settling of the weir body progress, at a certain point, the angle θ1 ″ of the horizontal force F1 ″ and the resultant force P1 ″ of the own weight Pd and the angle δ1 of each of the support links 2a and 2b. "Matches. At this time, the weir body becomes stationary at the water level h1 ″.
Therefore, when the flow rate is Q1, the water level difference between the upstream side and the downstream side is stabilized at Δh1 ″.

<5.5> Transition of water level difference at different flow rates (flow rate = Q2, Q3 ...)
FIG. 4 shows a comparative view showing the fluctuation of the water level difference with respect to the increase / decrease in the flow rate in the conventional flap type dive weir and the movable weir of the present invention.
FIG. 5 shows a simulation of fluctuations in the water level difference when the flow rate (Q1) set in <5.1 to 5.4> is further increased (in the case of flow rate = Q2, Q3,...). It is a thing.
As shown in FIG. 5, even if the flow rate increases or decreases, the operation of the movable weir does not change, and ascends and sinks repeatedly to settle down to a predetermined water level difference (Δh2 ″, Δh3 ″,...).
The gradient connecting the water level differences is gentler than the conventional flap type fixed weir.
Therefore, the movable weir according to the present invention can suppress the fluctuation range of the water level difference to a narrower range than the conventional flap type fixed weir.
This water level difference can be adjusted by setting the length of the support link 2 and the angle θ of the support link 2, and can be appropriately set by an allowable water level difference and structural limitations.

<5.6> Summary As described above, the movable weir according to the present invention appropriately designs the length of the support link, the mounting position, and the weight of the weir body, so that the water level between the upstream side and the downstream side of the water channel can be obtained. The dam body can be configured to move (float or sink) so that the angle of the resultant force between the horizontal force generated in the dam body due to the difference and the weight of the dam body is equal to the inclination angle of the support link.
According to this movable weir, even if the water level increases on the upstream side, no water falls over the weir body. And regardless of the increase or decrease of the flow rate, the water level difference between the upstream side and the downstream side can be kept substantially constant.

A movable weir according to a second embodiment of the present invention will be described.
In the present invention, as shown in FIG. 5, the movable weir can be configured such that each other end (fixed point 5) of the pair of support links 2 arranged in a substantially horizontal direction is arranged in the air.
If comprised in this way, since one set of support link 2 is installed in the air, maintainability becomes favorable.
At this time, since the imaginary line connecting one end of the pair of support links 2 is also in the substantially horizontal direction, the dam main body 1 may be further bent in the vertical direction from the hinged portion.

In the parallel crank mechanism Z in the movable weir according to the present invention, the line connecting the one ends 21 of the pair of support links 2 is limited to a substantially vertical direction or a substantially horizontal direction as in the first and second embodiments. is not.
For example, when the line connecting the one end 21 of the pair of support links 2 forms a certain angle with respect to the vertical direction, the dam body 1 starts from the location where the one end 21 of the pair of support links 2 is hinged. Further, the shape may be bent in the vertical direction.

A movable weir B opening X upstream Y downstream Z parallel crank mechanism 1 weir body 2 a set of support links 2a and 2b support link 21 one end 22 the other end 3a virtual vertical line 3b virtual horizontal line 41 and 42 hinge 5 fixed point

Claims (1)

A movable weir intervening in a waterway,
A weir body,
A pair of support links that form an acute angle with respect to the horizontal direction and are parallel to each other and are the same length;
One end of the set of support links is hinged to the weir body,
The other end of the set of support links is hinged to a fixed point, respectively.
A movable weir characterized by that.

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