JPH0433418Y2 - - Google Patents

Description

[Detailed explanation of the invention] <Industrial application field> This invention eliminates the negative pressure that occurs in the ventral channel of the guide vane when the opening degree of the guide vane is small in a split guide vane type once-through turbine, and improves cavitation. Regarding a once-through water turbine that prevents the occurrence of

<Prior Art> FIGS. 4 and 5 are partially sectional perspective views of a conventional split guide vane type once-through water turbine, and FIG. 5 is a sectional view taken along the line X--X in FIG. 4.

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, 30a and 30b
are divided guide vanes that adjust the water flow to 1/3 and 2/3, respectively, 31 is a guide vane shaft, 32 is a guide vane lever, 40 is a partition plate, 50 is an inlet pipe, 60 is a water turbine cover, and 70 is an air suction valve, 71
80 is an air suction valve cover, 80 is an outlet pipe, and 90 is a nozzle.

Generally, in a split guide vane type once-through water turbine, the width of the guide vane is divided at a ratio of 1:2, and a 30a guide vane is used when the water volume is small, and when the water volume increases, the 30b guide vane is activated to further increase the water volume. When this happens, use both guide vanes. In a once-through turbine with this structure, water that flows into the turbine casing from the inlet pipe is divided into an upper water flow and a lower water flow according to the opening degree of the guide vanes, passes through the guide vanes, and then joins again inside the runner 20. After flowing into the runner plate 22 and applying rotational force to the runner 20, the runner 2
Water is discharged from the bottom of 0 to the outside through an outlet pipe 80.

<Problems to be solved by the invention> However, in the once-through turbine having the above-described structure, when the opening degree of the guide vane 30a or 30b is made small, the waterway width d formed by the lower end surface of the guide vane 30a and the inner wall of the casing 10 becomes small; The width of the channel is widening further downstream. 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. As a result, ○a decreases in water turbine efficiency, ○b generates noise, and ○ erosion of guide vanes and runner blades due to vibration occurs.

This idea was developed in the range of small guide vane opening in a split guide vane type once-through turbine.
The present invention aims to provide a through-flow water turbine using a guide vane having a structure capable of eliminating negative pressure generated in an enlarged waterway formed between the ventral surface of the guide vane and the inner wall of a water turbine casing.

<Means and effects for solving the problem> The split guide vane type once-through water turbine of this invention is different from the conventional structure of the split guide vane type once-through water turbine in terms of the position of the split guide vane installed in the casing. However, the split guide vane to be installed should be installed within the expanded waterway downstream of the position where the channel width between the lower end ventral surface of one guide vane and the inner wall surface of the turbine casing is minimum. It has a tip opening on the ventral surface of the guide vane near the position where cavitation first occurs when small, and passes through the guide vane shaft and from the shaft end to the shaft of the other opposing guide vane. An opening formed on the ventral surface of the other guide vane in the expanded waterway downstream of the position where the channel width between the lower end ventral surface of the other guide vane and the inner wall surface of the turbine casing is the minimum. The device is characterized in that it is constructed with a communication path leading to the.

By configuring the guide vane structure of the split guide vane type once-through water turbine as described above, the first guide vane is operated in a range where the amount of water is small, and when the amount of water increases, the second guide vane is used.
When the amount of water increases, it operates to use both. When operating the first guide vane to reduce the flow rate, the first guide vane is opened and the second guide vane is closed to operate the once-through water turbine. Therefore, water flows only to the first guide vane side, and when the opening degree of the guide vane is small and negative pressure is generated on the ventral side of the guide vane, air flows to the tip opening of the second guide vane. is supplied to the opening side of the tip of the first guide vane.

In addition, when increasing the flow rate beyond the flow rate of the first guide vane, if the first guide vane is closed and the second guide vane is opened, water will be generated in the enlarged channel on the ventral side of the second guide vane. In response to the negative pressure generated, air is supplied from the ventral end opening side of the first guide vane to the ventral opening of the second guide vane, so that generation of negative pressure can be prevented.

Furthermore, if the flow rate is increased beyond the flow rate by the second guide vane, the first and second guide vanes will be opened, but since the opening degree of the guide vane is sufficient, the air supply is not necessary. There isn't.

<Example> An example of the present invention will be described below with reference to the drawings.

Figures 1 to 3 show the schematic configuration of a once-through water turbine using the split guide vane system according to the present invention.
2 is a perspective view showing the structure of the divided guide vane, and FIGS. 3A to 3B are diagrams showing the operating state of the once-through water turbine shown in FIG. 1.

In these figures, 10 is the water turbine casing. 30a
is a guide vane with a flow rate of 1/3, and 30b is a guide vane with a flow rate of 2/3.
The guide vanes 31a and 31b are the guide vane shafts of the guide vanes 30a and 30b, respectively.
32 is a guide vane bearing, 33 is a bearing frame, 34a
and 34b are guide vanes 30a and 30b
35 is a communication path with openings 34a and 34b, 40 is a partition plate, and 40a is a bearing. The divided guide vanes 30a and 30b are arranged on both sides of the partition plate 40, respectively, and the opening and closing operation of the guide vanes allows the through-flow turbine to be opened. It functions to regulate the flow rate of flowing water.

Cavitation is first performed in the range where the opening degree of the guide vane is small in the expanded waterway downstream of the position where the channel width between the lower end ventral surface of the guide vanes 30a and 30b and the inner wall surface of the turbine casing reaches the minimum value d. It has tip openings 34a and 34b at or near the generating position, and is perforated in the guide vane bodies 30a and 30b in the direction of the guide vane shafts 31a and 31b, respectively, passing through the shaft ends of the guide vane shafts 31a and 31b on the other side. Communication passages 35b, 35 of guide vanes 30b, 30a
It has a structure that communicates with a.

Therefore, in the range where the water flow rate is to be reduced, the guide vane 30b is closed and the guide vane 30a is used, and when the water flow rate is increased beyond that, the guide vane 30a is closed and the guide vane 30b is used, and when the water flow rate is further increased, both guide vanes are used. Guide vanes 30a and 30b are used.

When only the guide vane 30a is used, water flows in the direction of the arrow () as shown in FIG. Then, air is supplied from the opening 34b on the 30b side through the communication path 35 in the direction of the arrow (←).

In addition, when increasing the water flow rate, the guide vane 30a is closed and the guide vane 30a is
When moving b, the guide vane 30a moves in the opposite direction to A.
It is supplied from the side and blown out from the opening on the guide vane system 30b side.

In order to further increase the flow rate to 66% or more (2/3 or more), both guide vanes 30a and 30b will be opened, but in this state the guide vanes are already fully open. , there is no need to supply air.

In the above embodiments, the communication passage formed in the guide vane shaft is closed from one shaft end, but in some cases, a communication passage structured to penetrate both ends of the guide vane shaft may be used. It may be a set-up. At this time, it is preferable to provide a dustproof net at the end of the guide vane shaft to prevent dust from entering. Also, in this case, it is better to also provide a check valve.

<Effects of the invention> As is clear from the above explanation, the divided guide vanes can be structured to have a communicating path that opens from the ventral side of one guide vane to the ventral side of the local guide vane, as in the present invention. This makes it convenient to supply air to the guide vane side where it is needed.

Since there are no openings on the outside, even if a malfunction occurs, there will be no accidents such as water leakage.

By simply providing a communication path within the guide vane body, no special equipment is required, and the structure is simple.
Operation is reliable and simple.

Since the flow of air inside the guide vane is reversed, there is an advantage that even if the passage hole becomes clogged, it will be discharged during the reverse rotation.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main parts of a split guide vane type once-through water turbine according to the present invention, Fig. 2 is a perspective view showing the schematic structure of the split guide vane of the once-through water turbine shown in Fig. 1, and Figs. 3 A and B. is a cross-sectional view of the main parts showing the operating status of the once-through water turbine in Figure 1, Figure 4 is a perspective view of a conventional split guide type once-through water turbine, and Figure 5 is a cross-sectional view taken along the line X-X in Figure 4. . In the drawing, 10...water turbine casing, 30a...
Guide vane with flow rate 1/3, 30b...Water flow rate 2/3
guide vane, 31a...guide vane 30a
Guide vane shaft, 31b...guide vane 30
b guide vane shaft, 32... guide vane bearing, 33... bearing frame, 34a... guide vane 3
0a side opening, 34b...Guide vane 30b side opening, 35...Communication path.

Claims (1)

[Scope of utility model registration request] In a split guide vane type once-through turbine, the opening degree of the guide vane is adjusted in the expanded waterway downstream of the position where the waterway width between the lower end ventral surface of one guide vane and the inner wall surface of the turbine casing is the minimum. When small, the guide vane has a tip opening on the ventral surface of the guide vane near the position where cavitation first occurs, and passes through the shaft of the guide vane,
An expanded waterway passing from the shaft end through the shaft of the other opposing guide vane, downstream of the position where the waterway width between the lower end ventral surface of the other guide vane and the inner wall surface of the turbine casing is the minimum. A split guide vane type once-through water turbine, characterized in that a communication passage is provided inside the guide vane to reach an opening formed on the ventral surface of the other guide vane.