JPH0110441Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to a once-through water turbine having a structure that eliminates negative pressure generated in the ventral flow channel of the guide vane when the opening degree of the guide vane is reduced. .

<Prior art> Fig. 8 and Fig. 9 show the main structure of a typical conventional once-through water turbine. FIG.

In these figures, 10 is a water turbine casing, 20 is a runner, 21 is a runner shaft, 22 is a runner blade, 23 is a bearing, 24 is a bearing frame, 30 is a guide vane, 31 is a guide vane shaft, 32 is a rotating lever, and 50 is an inlet pipe, 60 is a cover, 70 is an air suction valve, 71 is an air suction valve cover, 80 is an outlet pipe,
90 is a nozzle.

In the once-through water turbine having the above structure, water flowing into the casing from the inlet pipe 50 is divided into an upper water flow and a lower water flow depending on the opening degree of the guide vane 30.
The water joins together again and flows into the runner 20, collides with the runner blades 22, imparts a rotational force to the runner 20, and is then discharged to the outside through the outlet pipe 80 from the lower part of the runner.

<Problems to be solved by the invention> However, in the once-through turbine having the above-mentioned structure, when the opening degree of the guide vanes 30 is reduced, the guide vanes 30
The width d of the waterway formed by the lower end of the casing 10 and the inner wall of the casing 10 is small, and the width of the waterway widens downstream from it.

Therefore, water flowing downstream from a narrow waterway (width d) suddenly expands in the expanded waterway, creating a strong negative pressure. Further, since the flow path also has a bend, a vortex flow occurs. Therefore, ○a decrease in water turbine efficiency, ○b noise generation, and ○ erosion of guide vanes and runner blades due to hydraulic vibration.

This invention aims to provide a through-flow water turbine that eliminates the negative pressure generated in the enlarged water channel between the vent side of the guide vane and the inner wall of the casing when the opening degree of the guide vane is small.

<Means and actions for solving the problem> The once-through turbine of this invention has the same position of the guide vane installed inside the casing as the conventional structure, but the amount of water supplied to the runner is controlled by the guide vane. In a once-through water turbine that is restricted by opening and closing, a first air circulation hole is provided that penetrates the guide vane shaft in the axial direction of the guide vane shaft and opens to the atmosphere, and is provided with a first air circulation hole that is closest to the inner wall of the water turbine casing. A tip portion opens on the ventral surface of the guide vane in the vicinity of a position where cavitation first occurs downstream of the ventral portion of the opposing guide vane, and a distal end portion communicates with the first air circulation hole. It is characterized by providing a second air circulation hole.

In a once-through turbine configured in this way, there is an air circulation hole through which outside air flows into the guide vane shaft, and the terminal end portion communicates with this air circulation hole, so that the outer surface of the lower end of the guide vane and the inside of the water turbine casing are connected to each other. At the opening degree where the inter-wall channel width forms the minimum width, the end opened on the ventral side of the guide vane near the position where cavitation first occurs in the enlarged channel downstream of the ventral side minimum channel width position. Since the second air circulation hole has an end opening, even if the opening degree of the guide vane is made small and negative pressure is generated in the ventral enlarged channel, the guide vane opens to the atmosphere. Air is introduced into the air circulation hole through the shaft end opening of the vane and acts to compensate for the negative pressure (with respect to atmospheric pressure) within the enlarged waterway, thereby preventing cavitation from occurring.

<Example> Hereinafter, an example of the present invention will be described using the drawings.

1 and 2 are a perspective view of a guide vane 30 constituting a once-through water turbine according to each invention, and a sectional view of a main part showing the relative positional relationship between the inner wall surface 10 of a water turbine casing and the guide vane 30.

Guide vane 30 of once-through water turbine based on this invention
, a circular hole 35 is bored in the guide vane shaft 31 from the shaft end in the direction of the central axis, and a circular hole 35 is formed in the guide vane body.
A plurality of (four in the figure) round holes 36 from 5 to 5 are bored toward the ventral side of the guide vane. Then, at the opening degree at which the channel width between the lower end outer surface of the guide vane 30 and the inner wall surface of the casing 10 forms the minimum width a, in the enlarged channel downstream of the minimum channel width position E on the ventral side of the guide vane. The ventral opening 36a of the round hole 36 described above is provided at the position where cavitation first occurs (downstream by a distance from position E), and the shaft end opening 3 of the guide vane is provided.
From 5a, air circulation holes are provided to allow air to flow into the ventral side of the guide vane.

Such air circulation holes 35 are provided in the guide vane shaft 31 and guide vane body of the guide vane 30.
By providing 36 and 36, when the opening degree of the guide vane is reduced, negative pressure generated in the enlarged channel on the ventral side of the guide vane can be eliminated, and cavitation can be prevented from occurring.

The shaft end opening of the guide vane shaft 31 of the guide vane shown in FIGS. 1 and 2 is exposed directly (or through a dustproof net) to the atmosphere, but as shown in FIG. In the hole of the shaft end 35a,
Using the rotary lever and check valve 37, the air pipe 3
A structure may also be adopted in which air is taken in from inside the cover 60 through 8. When you have a structure like this,
Air to be supplied to the ventral side of the guide vane 30 is sucked from within the cover of the once-through water turbine. The cover 60 normally sucks air through an air suction valve and has a structure that doubles as a muffler and a dustproof device, so even if the check valve 37 is damaged and water flows backwards,
Since water does not leak outside and no intake noise comes out, quieter operation is possible, and there is no chance of foreign matter getting in, so the filter can be cleaned without clogging the holes. No maintenance is required. Note that the rotation lever 32 and the air pipe 38 can be replaced with hoses made of rubber or the like, and the flexibility of the hoses can cope with the operation (swivel) of the guide vanes.

On the other hand, when the guide vane opening is 50 to 60% or more, air supply is no longer necessary;
If it is less than 30%, the water flow of the once-through turbine will decrease, so the amount of air will not be needed as much, and it will be sufficient to supply a certain amount of air commensurate with the guide vane opening.
This kind of guide vane opening (water wheel/water volume) q
The relationship between (%) and the air supply amount Q is shown in the characteristic diagram shown in FIG.

Therefore, it is possible to provide an air supply mechanism that can adjust the amount of air supplied from the air flow hole of the guide vane shaft 31 to the ventral flow channel of the guide vane 30 in accordance with the opening degree of the guide vane. ideal.

In order to satisfy such requirements, an air flow rate adjusting device having the structure shown in FIGS. 5 to 7 is attached to the shaft end of the guide vane shaft 31 of this embodiment described above, and the flow rate of the guide vane can be adjusted. Functions can be performed smoothly.

The main structure of a guide vane equipped with this air flow rate adjusting device is shown in FIGS. 5 to 7.

In Figs. 5 to 7, 30 is a guide vane;
31 is a guide vane shaft, 35 is a first air circulation hole provided in the guide vane shaft, 39 is a guide vane bearing fixed to the casing, 39a is a guide vane bearing frame, 100 is a rotary valve, 101 is a rotary valve 10
102 is an air passage provided at rotary valve 10.
0 is the valve space provided in the valve box, 111 is an opening provided in the valve box and has a wedge-shaped air passage as shown in FIG. 7, 120 is an air pipe connection joint, 38 is an air pipe, and 112 is a water leakage hole. Prevent packing.

FIG. 6 is a cross-sectional view taken along the Y-Y line in FIG. overlap, allowing a large amount of air to pass through. When the opening degree of the guide vane becomes large, the valve space 1 increases as shown by the arrow in Fig. 7.
02 and the air passage 101 will be reduced, and eventually the opening 111 of the valve box and the valve space 102 will no longer overlap, and water will no longer flow. In this device, the air pipe 38 can be opened to the atmosphere, but as in the case of FIG. 3, it can also be opened inside the water turbine cover to prevent intake noise from going outside. Further, a throttle valve is provided in the middle of the air pipe 38 to adjust the amount of air, and the relative position of the entire valve box 110 or the guide vane shaft 31 and the rotary valve 100 can be adjusted, so that the amount of air flow can be adjusted. You can also do that.

In addition, in the above embodiment, the valve body is a cylindrical valve, but the same type of valve such as a disc valve, butterfly valve, funnel-shaped funnel valve, or gate valve may be used to guide the adjustment and closing of the air amount. A structure may be adopted in which the operation is performed together with the vane operation. In the above embodiment, only a single guide vane was described, but the present invention is also applicable to a split guide vane structure.

<Effect of the invention> As is clear from the above explanation, the once-through water turbine of the invention has an air circulation hole from the guide vane shaft end to the ventral side of the guide vane, so that the opening degree of the guide vane can be adjusted. Even if a situation occurs where negative pressure is generated in the ventral enlarged channel due to a small amount of pressure, cavitation will not occur because air is injected from the atmosphere into the enlarged channel.

Therefore, the efficiency of the water turbine is improved and the noise is reduced.

Guide vane,
The runners will not be worn out.

Even in once-through water turbines, cavitation may occur in the runner blades, but since the guide vanes are injecting air, these air bubbles are mixed into the water flow, so cavitation in the blades can occur. Less wear and tear on the blade.

In addition, as in the embodiment shown in Fig. 3, by using a check valve and a rotary lever in the air circulation hole at the end of the shaft of the guide valve, and creating a structure in which air is taken in from inside the water turbine cover via an air pipe, If the air to be supplied into the enlarged ventral channel of the guide vane is suctioned from within the water turbine cover, air suction noise will not leak outside, allowing for quieter movement. Furthermore, since no dust or the like from the outside air is sucked in, clogging does not occur.

Furthermore, even if the check valve is damaged, water will not leak outside, increasing reliability.

In addition, as shown in Figures 5 to 7, if an air flow rate adjustment device is attached to the end of the air flow hole at the shaft end of the guide vane, the optimum amount of air can always be supplied, increasing efficiency. Can be maintained high.

○B There is no need for a structure with a check valve to prevent backflow of water when the guide vane is opened to a large degree.

○C The number of moving parts such as throttle valves is reduced, and the valve opening is automatically adjusted with guide vane operation.
High reliability and reliable operation.

○D The structure is simple, and since it is located at the end of the shaft (outside the machine), it is easy to disassemble and inspect, and has excellent maintainability.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the guide vanes constituting the once-through water turbine of the present invention, Fig. 2 is a diagram showing the relative positional relationship between the guide vanes shown in Fig. 1 and the inner wall of the water turbine casing, and Fig. 3 is a diagram of the once-through water turbine of the present invention. A perspective view of the main parts showing the arrangement of the air pipe connected to the shaft end of the guide vane,
Fig. 4 is a characteristic diagram showing the relationship between the opening degree of the guide vane and the air supply amount, and Fig. 5 is a cross-sectional view of the main part structure of the air flow rate adjustment device attached to the end of the guide vane shaft in the once-through water turbine according to the present invention. , FIG. 6 is a sectional view taken along the Y-Y arrow in FIG. 5, and FIG. 7 is an explanation showing the overlapping state of the valve space of the rotary valve and the opening of the valve body in the air flow rate adjusting device shown in FIG. 5. Figure, 8th
The figure is a partial cross-sectional perspective view of a conventional structure of a once-through water turbine.
The figure is a sectional view taken along the line X--X in FIG. 8. In the drawings, 21...Runner shaft, 30...Guide vane, 31...Guide vane shaft, 32...Rotary lever, 35...First air circulation hole, 35a...Shaft end opening, 36...Second Air circulation hole, 36a...
Air flow passage opening, 37... Check valve, 38... Air pipe, 39... Guide vane bearing, 39a...
Guide vane bearing frame, 100...Rotary valve, 101
... Air passage formed in the rotary valve, 102 ... Valve space, 110 ... Valve box, 111 ... Air passage in valve box, 120 ... Air pipe connection joint.

Claims (1)

[Scope of utility model registration request] In a once-through water turbine that limits the amount of water supplied to the runner by opening and closing guide vanes, a first air circulation hole is provided that penetrates the guide vane shaft in the axial direction of the guide vane shaft and opens to the atmosphere. , the tip part opens on the ventral surface of the guide vane in the vicinity of the position where cavitation first occurs downstream of the ventral part of the guide vane that faces the inner wall of the turbine casing most closely, and the distal end part opens in the vicinity of the position where cavitation first occurs. Said first
A through-water turbine characterized in that a second air circulation hole is provided that communicates with the air circulation hole.