JPH11166469A - Hydraulic machinery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress pulsation of water pressure, emission of noise, generation of vibration, etc., resulting from a whirl without drop of the efficiency of a hydraulic wheel while the construction costs are suppressed to possible minimum. SOLUTION: A resilient material layer 11 is furnished on the inner surface which forms the water flowing surface of a suction pipe 7 to lead the water from a runner 4 to a discharge conduit. Accordingly a whirl 8 generated in the suction pipe 7 will never collide directly with the pipe surface consisting of metal, and the collisional energy of the whirl 8 is absorbed by the resilient material layer 11, which should suppress the pulsation of water pressure, emission of noise, generation of vibration, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic machine having a suction pipe, and more particularly to a hydraulic machine for reducing water pressure pulsation in a suction pipe.

[0002]

2. Description of the Related Art Generally, in a hydraulic machine such as a water turbine or a pump turbine, when the hydraulic machine is operated at a partial load, a pressure lower than the atmospheric pressure is applied to a central portion of a suction pipe by a swirling flow from a runner outlet. A spiral cavity called whirl (hereinafter called whirl) is generated. When the whirl sways in the suction pipe, the water pressure pulsation increases, and the abnormal sound and vibration generated when the whirl collides with the inner wall of the pipe and collapses become a factor inhibiting the stable operation of the hydraulic machine.

FIG. 15 is a vertical sectional view of a general Francis turbine. When water is rectified by a stay vane 2 and a guide vane 3 from a casing 1 and flows into a runner chamber, a runner 4 is driven to rotate and is driven through a main shaft 5. Thus, the generator 6 is driven. On the other hand, the water that has driven the runner 4 flows through the suction pipe 7 to a water discharge passage (not shown).

[0004] The guide vanes 3 have an important role in that the amount of water corresponding to the amount of power generation flows into the runner by changing the opening of each guide vane. Then
The water flowing out of the runner exhibits various behaviors depending on the operation state of the turbine. Especially, the rotational speed component (turning speed) is the same as the runner on the low drop side and the partial load area, and the high speed is higher than the efficiency point. On the head side and in the overload region, there is a speed component in the reverse rotation direction. Further, since this swirling flow does not have a uniform distribution from the inner diameter side to the outer diameter side of the runner, an unbalanced flow is caused in the flow in the suction pipe, and the whirling 8 is generated near the lower end of the runner cone 4a.

FIGS. 16 (a), (b), (c), (d)
Is a diagram showing an example of the generation behavior of this whirl, and the operating conditions (head, guide vane opening) of the hydraulic machine
The generated behavior changes greatly, and the generated whirl behavior affects the pressure change in the suction pipe.

That is, when the generated whirl oscillates greatly inside the suction pipe, a large hydraulic pulsation is caused. In addition, when colliding with the pipe wall of the suction pipe, noise and vibration are caused, and these water pressure pulsation, impact sound, and vibration may affect not only the suction pipe but also the entire power plant,
The operation of the power plant may be hindered.

[0007]

SUMMARY OF THE INVENTION
As a means for reducing water pressure pulsation, noise, and vibration due to whirl generated inside the suction pipe, a method of injecting air into the suction pipe to stabilize the whirl, or as shown in FIG. A method of suppressing the whirl by attaching the swirling flow prevention member 9 as described above has been proposed.

However, in the case of the former, it is an absolute condition that air having a pressure higher than the pressure in the suction pipe is supplied. Is difficult under natural circumstances, which requires a dedicated compressor for generating high-pressure air, which is problematic in terms of construction costs.

On the other hand, in the latter case, it is necessary to make the swirling flow prevention member large enough to fit the water turbine in order to exert the effect of suppressing the whirl. For this reason, when applied to a large water turbine, the swirl flow prevention member itself becomes large in size.Therefore, not only the manufacturing method, but also a mounting method that takes into account the prevention of falling off during operation into the suction pipe becomes a problem. There is a problem that the swirling flow prevention member cannot be attached depending on the structure.

In view of the foregoing, the present invention provides a hydraulic power plant capable of effectively suppressing generation of water pressure pulsation, noise, vibration, etc. due to whirl without reducing the construction cost and reducing the efficiency of the water turbine. The aim is to get the machine.

[0011]

According to the first aspect of the present invention,
In a hydraulic machine having a suction pipe for guiding water flowing out of a runner to a water discharge channel, an elastic material layer is provided on an inner surface of the suction pipe forming a water flow surface.

The invention according to a second aspect is characterized in that, in the first aspect, the elastic material layer is formed by sealing a gas in a hollow body made of an elastic material.

[0013] The invention according to claim 3 is the invention according to claim 1 or 2.
In the invention described above, a plurality of elastic material layers are provided on the inner surface of the suction pipe at appropriate intervals in the flowing water direction.

The invention described in claim 4 is the first or second invention.
In the invention described above, the elastic material layer is locally provided on the inner surface of the curved portion of the suction pipe.

Further, the invention according to claim 5 is characterized in that an elastic material is interposed between the suction pipe and the concrete portion covering the suction pipe.

[0016] The invention according to claim 6 is characterized in that water having a pressure relatively higher than the pressure in the suction pipe is injected into the suction pipe to suppress the whirl generated by the swirling flow from the runner outlet. I do.

Further, the invention according to claim 7 is the same as the invention according to claim 6.
In the described invention, one or more water inlets are provided in the pipe wall of the suction pipe, and high-pressure water is injected into the suction pipe from the water injection port.

According to an eighth aspect of the present invention, in the invention of the sixth aspect, a high-pressure water supply hole for injecting high-pressure water into a suction pipe is provided on a main shaft connecting the runner and the generator.

According to a ninth aspect of the present invention, in the invention of the seventh or eighth aspect, an automatic control valve for controlling water injection timing is provided in a water supply pipe route for supplying high-pressure water into the suction pipe. It is characterized by being.

According to a tenth aspect of the present invention, in the ninth aspect of the present invention, the automatic control valve is opened when the operating state of the guide vane is in the range of 40 to 70% of the guide vane opening corresponding to the rated output of the turbine. In other operating states, the closed state is maintained.

Further, in the invention according to claim 11, in the invention according to claim 9, an operation state monitoring device is installed on the suction pipe tube wall, and the measured vibration value and noise value are set in advance. The automatic control valve is opened when the set value is exceeded.

According to the twelfth aspect of the present invention, there is provided the sixth to first aspects.
The invention according to any one of the first to eighth aspects, characterized in that high-pressure water is taken from a casing or a penstock.

Further, according to a thirteenth aspect of the present invention, in the invention according to any one of the sixth to twelfth aspects, an air mixing device is connected to a water injection pipe route for supplying high-pressure water into the suction pipe. In addition, air is mixed into high-pressure water to be injected.

[0024]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, pressurized water from a casing 1 flows into a runner 4 via a stay vane 2 and a guide vane 3, and drives the runner 4 to rotate. Then, the running water flowing out of the runner 4 is discharged to a water discharge passage (not shown) via the suction pipe 7. The suction pipe 7 includes an upper suction pipe 7a, a bent pipe 7b, and an enlarged pipe 7c. In the case of a hydroelectric power plant, the suction pipe 7 is generally buried in concrete 10.

An elastic material layer 11 is attached to the inner surface of the suction pipe 7 forming the flowing water surface by a plurality of attachment bolts 12, as shown in FIG.
The elastic material layer 11 is attached to the inside of the suction pipe 7 so as not to cause a step, so that the water turbine performance is not adversely affected. The thickness of the elastic material layer 11 may be a minimum thickness capable of absorbing the collision energy.

Generally, the water flowing out of the runner 4 exhibits various behaviors depending on the operation state of the water turbine as described above.
In particular, the speed component in the rotation direction has a speed component in the same rotation direction as the runner on the low drop side and the partial load region and a reverse rotation direction in the high drop side and the overload region near the maximum efficiency point. Since this swirling flow is not uniform from the inner diameter side to the outer diameter side of the runner 4, an unbalanced flow is generated in the flow in the suction pipe 7, and a spiral cavity (whirl) is generated near the lower end of the runner. In particular, when the turbine is operated at a partial load, the whirl 8 oscillates in the suction pipe 7 to increase the water pressure pulsation, and collides with the inner wall of the suction pipe 7 so that the water wheel collapses. cause.

According to the present invention, however, since the elastic material layer 11 is layered on the inner surface of the suction pipe 7 forming the water flow surface, the above-mentioned whirl 8 directly collides with the metal surface constituting the suction pipe 7. Therefore, it collides with the elastic material layer 11, and the collision energy generated at the time of the collision is absorbed by the deformation of the elastic material layer. Therefore, Whirl 8
The water pressure pulsation, the impact sound and the vibration generated at the moment when the water directly collides with the metal part on the flowing surface of the suction pipe are effectively reduced.

In the above-described embodiment, the elastic material layer 11 may be formed uniformly over the entire surface, or may be formed in a hollow shape by using an elastic material and a gas is sealed in the hollow. Thus, in this case, an excellent cushioning effect is generated due to the flexibility of the gas, and the ability to absorb the collision energy generated by the collision of the whirl 8 is further improved. Further, since the gas is sealed in the elastic material layer, the weight can be reduced and the cost can be reduced.

FIG. 1 shows a structure in which the elastic material layer 11 is provided on the entire inner surface of the suction pipe 7, but as shown in FIG. 3, the elastic material layer is divided into a plurality of elastic material layers 11a and 11b. It may be divided and attached piecewise to the inner surface of the suction pipe 7. In this case, the optimum mounting position is determined based on observation results such as a model test. Also in this case, the same performance as that shown in FIG. 1 is exhibited, and by dividing the elastic material layer into a plurality, the use amount of the elastic material can be reduced, which is economical.

FIGS. 4 and 5 are views showing another embodiment of the present invention. The elastic material layer 11 is attached only to the flowing water surface on the inner diameter side and the outer diameter side of the bent pipe portion 7b of the suction pipe 7. ing.

Generally, a whirl 8 generated at the lower end of the runner
In the case of a curved flow path, there is a characteristic that the flow cannot be faithfully performed along the curved shape. For this reason, most of the whirl collides with the inner wall surface of the bent pipe portion. Therefore,
In the present invention, since the elastic material layer 11 is provided on the inner and outer flowing water surfaces of the bent pipe portion 7b where the whirl is likely to collide, the whirl collision phenomenon is reduced by this elastic material layer. Vibration and noise can be reduced. Further, since the elastic material layer 11 is provided locally, the amount of the elastic material layer used can be reduced, which is economical. Further, the inner diameter side and the outer diameter side of the bent pipe portion of the suction pipe are not shown in FIG. As shown in FIG. 5, since the location is relatively close to a plane in shape, the mounting work is also easy.

FIG. 6 is a view showing still another embodiment of the present invention, wherein an elastic material layer 11 is interposed between a suction pipe 7 and a concrete portion 10 provided so as to cover the suction pipe 7. Have been. Therefore, the collision energy due to the whirl is absorbed by the deformation of the elastic material layer 11 and does not affect the concrete in close contact with the outer surface of the elastic material layer, and vibration is induced in the peripheral equipment of the draft tube and the entire power plant building. Nothing.

FIG. 7 is a view showing another embodiment of the present invention. One or a plurality of water inlets 20 are provided on the wall surface of the suction pipe 7, and the suction pipe 7 is passed through the water inlet 20. High-pressure water is injected into the inside of the. Since the pressure in the suction pipe is equal to the water level of the discharge channel, a pressure higher than the water level of the discharge channel is used.

However, by injecting the high-pressure water into the suction pipe, the whirl shape changes from a thin string-like vortex to a stable shape having a large cavity inside, and the whirl that oscillates largely disappears. The flow shifts to a flow in which the water flow is reduced, and the water pressure pulsation value in the suction pipe can be greatly reduced.

FIGS. 8 (a) and 8 (b) are diagrams showing changes in behavior of the whirl generated from the lower end of the runner before and after injecting high-pressure water into the suction pipe as described above, and FIG. Of the water pressure pulsation value (ΔH) is expressed as a ratio to the effective head (H) on the horizontal axis of the turbine output, where A indicates the case where water injection is not performed and B indicates the case where water injection is performed.

FIG. 9 is a view showing a modification of the hydraulic machine shown in FIG. 7, in which a high-pressure water supply hole 21 reaching the runner cone 4a is provided inside a main shaft 5 connecting the runner 4 and the generator 6. A water injection pocket 22 communicating with the high-pressure water supply hole 21 is provided on the outer periphery of the main shaft 5, and a water injection pipe 23 for supplying high-pressure water from outside is connected to the water injection pocket 22. The high-pressure water supply hole 21 has a size such that the main shaft strength does not decrease.
It is desirable to provide three. Further, the high-pressure water to be injected needs to have a higher pressure than the pressure in the suction pipe.

When high-pressure water is supplied from the water supply pipe 23 to the high-pressure water supply hole 21 via the water injection pocket 22, the high-pressure water is injected into the suction pipe 7. Therefore, the high pressure water suppresses the whirl 8 generated by the swirling flow from the runner outlet, stabilizes the whirl 8 generated in the suction pipe, and greatly reduces the water pressure pulsation value in the suction pipe.

Further, as shown in FIG.
In the middle of 3, an automatic control valve 24 for controlling high-pressure water injection timing is provided. Thus, the high-pressure water can be injected into the suction pipe 7 with good timing by the automatic control valve 24, and the whirl 8 in the suction pipe 7 can be accurately suppressed.

By the way, as can be seen from the hydraulic pressure pulsation change diagram in the suction pipe shown in FIG. 8C, the water pressure pulsation rapidly increases from around 70% of the turbine output when the turbine output is small, based on the turbine output. Is evident. In addition, the water turbine output 40
%, The whirl does not form a thin vortex, so that water pressure pulsation, vibration and noise due to the whirl are significantly reduced. Therefore, this water pressure pulsation value increases sharply.
It is more effective to inject high-pressure water only in the operation range of 0% to 40% turbine output.

Therefore, as shown in FIG. 11, an arithmetic unit 25 is connected to the automatic control valve 24. The arithmetic unit 25 controls the flow rate of the water turbine through the arithmetic unit 25 in relation to the opening degree of the guide vane 3. The opening of the automatic control valve 24 may be controlled. Therefore, in this case, water injection corresponding to the water turbine operation state is performed, and accurate whirl suppression is performed. Further, as shown in FIG. 12, an operation state monitoring device 26 for monitoring the operation state of the water turbine is attached to the pipe wall of the suction pipe 7, and a whirl 8 is generated in the suction pipe 7.
When it is detected that any of the water pressure pulsation value, the noise value, and the vibration value measured in Step 6 is equal to or higher than a predetermined rated value, the automatic control valve 24 may be opened. it can. In this case, the whirl generated inside the suction pipe can be immediately suppressed by linking the automatic control valve 24 and the operation state monitoring device 26.

As the high-pressure water, it is sufficient to use a high-pressure water having a pressure higher than the discharge channel water level. As shown in FIG. 13, the water injection pipe 23 is connected to the penstock 27, and the high-pressure water is supplied from the penstock 27. You may take water. The same effect can be obtained by taking water from the casing 1 instead of the penstock 27. In this case, external equipment for generating high-pressure water is unnecessary compared with the air supply system that controls the whirl by injecting high-pressure air generated by the compressor into the suction pipe, which is a great advantage in terms of construction costs. is there.

FIG. 14 is a view showing another embodiment of the present invention. The automatic control valve 24 is connected to an air mixing machine 28, and a certain amount of high-pressure water injected into the suction pipe 7 is supplied to the automatic control valve 24. Of air is mixed. The amount of air to be mixed is controlled by the air mixing machine 28. In addition, by forming a throttle portion having a low pressure temporarily in the internal path of the air mixing machine, air can be easily mixed.

Generally, the flow inside the suction pipe is unbalanced due to the difference in the speed of the swirling flow between the inner diameter side and the outer diameter side, as described above. Further, when air having a low specific gravity is injected into the rotating water, there is a characteristic that the air instantaneously moves to the inner diameter side. This embodiment utilizes this principle, and instantly stabilizes the whirl generated on the inner diameter side of the suction pipe by injecting a certain amount of air into high-pressure water and pouring it into the suction pipe. Can be done. Therefore, water pressure pulsation, noise, and vibration generated by the whirl can be effectively reduced.

In FIGS. 10 to 14, a description has been given of the case where high-pressure water is supplied from the high-pressure water supply hole 21 provided on the main shaft, but the high-pressure water is supplied from the inlet provided on the wall of the suction pipe 7. Also applicable to

[0045]

As described above, the present invention can reduce water pressure pulsation, noise, and vibration caused by whirl generated during partial load operation of a hydraulic machine, or can reduce swirling flow from a runner outlet. Can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a hydraulic machine showing a first embodiment of the present invention.

FIG. 2 is a plan sectional view taken along the line AA of FIG. 1;

FIG. 3 is a longitudinal sectional view showing another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing still another embodiment of the present invention.

FIG. 5 is a plan sectional view taken along line AA of FIG. 4;

FIG. 6 is a longitudinal sectional view showing another embodiment of the present invention.

FIG. 7 is a longitudinal sectional view showing still another embodiment of the present invention.

FIGS. 8A and 8B are diagrams showing behavior changes of a whirl generated from a lower end of a runner before and after water injection,
(C) is a diagram showing a change in a water pressure pulsation value at that time.

FIG. 9 is a longitudinal sectional view showing another embodiment of the present invention.

FIG. 10 is a view showing another modification of FIG. 9;

FIG. 11 is a view showing another modification of FIG. 10;

FIG. 12 is a view showing still another modified example of FIG. 10;

FIG. 13 is a longitudinal sectional view showing another embodiment of the present invention.

FIG. 14 is a longitudinal sectional view showing still another embodiment of the present invention.

FIG. 15 is a longitudinal sectional view of a general Francis turbine.

FIGS. 16 (a), (b), (c), and (d) are diagrams showing how whirl occurs.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 2 Stay vane 3 Guide vane 4 Runner 5 Main shaft 6 Generator 7 Suction pipe 8 Whirl 10 Concrete 11 Elastic material layer 20 Water inlet 21 High pressure water supply hole 22 Water pouring pocket 23 Water pouring pipe 24 Automatic control valve 25 Arithmetic unit 26 Operating state Monitoring device 27 Penstock 28 Air mixing machine

Claims (13)

[Claims] 1. A hydraulic machine having a suction pipe for guiding water flowing out of a runner to a water discharge channel, wherein an elastic material layer is provided on an inner surface of the suction pipe forming a water flow surface. 2. The hydraulic machine according to claim 1, wherein the elastic material layer is a hollow body made of an elastic material, and a gas is sealed therein. 3. The hydraulic machine according to claim 1, wherein a plurality of elastic material layers are provided on the inner surface of the suction pipe at appropriate intervals in a flowing water direction. 4. The hydraulic machine according to claim 1, wherein the elastic material layer is provided locally on the inner surface of the curved portion of the suction pipe. 5. A hydraulic machine having a suction pipe for guiding water flowing out of a runner to a discharge channel, wherein an elastic material layer is interposed between the suction pipe and a concrete portion covering the suction pipe. Hydraulic machine. 6. A hydraulic machine having a suction pipe for guiding water flowing out of a runner to a water discharge passage, wherein water having a pressure relatively higher than the pressure in the suction pipe is injected into the suction pipe, and swirling flow from a runner outlet is used. A hydraulic machine characterized by suppressing the generation of whirl. 7. The hydraulic machine according to claim 6, wherein one or a plurality of water inlets are provided in a pipe wall of the suction pipe, and high-pressure water is injected into the suction pipe from the water injection port. 8. The hydraulic machine according to claim 6, wherein a high-pressure water supply hole for injecting high-pressure water into the suction pipe is provided on a main shaft connecting the runner and the generator. 9. The hydraulic machine according to claim 7, wherein an automatic control valve for controlling water injection timing is provided in a water injection pipe route for supplying high-pressure water into the suction pipe. 10. The automatic control valve opens during an operation state in a range of 40 to 70% of the guide vane opening corresponding to the rated output of the turbine, and is kept closed in other operation states. The hydraulic machine according to claim 9, wherein: 11. An operation state monitoring device is installed on a wall of the suction pipe, and an automatic control valve is opened when a measured vibration value and a noise value exceed predetermined values. The hydraulic machine according to claim 9, wherein: 12. The hydraulic machine according to claim 6, wherein the high-pressure water is taken from a casing or a penstock. 13. A water injection pipe route for supplying high-pressure water into the suction pipe, wherein an air mixing device is connected to mix air into the high-pressure water to be injected. The hydraulic machine according to any one of the above.