JPS60212675A - S type tubular water turbine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention relates to a low head water turbine in which the kinetic energy of the flow at the runner outlet is extremely large, and the diffuser function that can efficiently convert the energy of this flow into pressure energy. Bend the suction pipe, especially the suction pipe, into an S-shape and
The present invention relates to an S-shaped tubular water turbine having a bent portion and a second bent portion that is reversed to the bent portion.

[Prior art and its problems]

Recently, the development of ultra-low head hydraulic energy with a head of 20 m or less has attracted attention7, but bulb turbines or S-type tubular turbines are generally not accepted as ultra-low head aquatic plants, but valve turbines and small The capacity machine uses an S-type tubular water turbine.

In Japan, the economic efficiency of S-type tubular water turbines was reviewed, and the first unit (Niigata Prefectural Tainai No. 3 Power Plant, output 2.15 MW, head 14.12 m) went into operation in 1983.

This S-type tubular water turbine is a type of tubular water turbine in which the suction pipe is bent into an S-shape and passes through the water wheel shaft, and a generator is installed downstream of the water turbine. In these ultra-low head turbines, the velocity energy at the suction pipe inlet, which is the outlet of the runner, is large and reaches 50% of the right dynamic head, so the suction pipe has a large influence on the turbine efficiency.

In general, the efficiency characteristics of S-type tubular water turbines are basically the same as those of pulp water turbines, but in large flow areas they are lower than pulp water turbines with straight suction pipes (see Figure 2).

Therefore, as a result of analyzing the amount of S formed in the S type tubular turbine and the flow state inside the pipe, it was found that the flow separated from the inner wall on the inside of the second half of the first bend on the upstream side, and as a result, a large amount of kinetic energy of the flow at the runner exit was sucked out. It was discovered that the reason why the efficiency of S-type tubular water turbines is lower than that of pulp water turbines, which have straight, unbent pipes, was revealed because pressure energy cannot be efficiently converted into pressure energy using pipes (see Figure 3).

In order to reduce this separation and improve efficiency, it is necessary to increase the horizontal length L of the suction pipe < (TyD≧6.5, where D is the runner diameter), and the exit cross-section relative to the inlet cross-section of the suction pipe. The suction pipe cross-sectional area expansion rate AR, which is the area ratio, is decreased (
It is clear from the theory of known diffusers that it is necessary to suppress AR≦3.5), and this problem 8-1:
Therefore, in the S-type tubular water storage, the kinetic energy at the outlet of the suction pipe cannot be made sufficiently small, and the efficiency of the water turbine, that is, the output of the power plant, is correspondingly low.

[Purpose of the invention]

Therefore, in view of the above points, this invention focuses on the fact that separation can be prevented by injecting a small amount of high-energy fluid into the position immediately after the separation of the fluid in the suction pipe, and aims to improve the efficiency of the S-type tubular water turbine. The purpose of the present invention is to provide an S-type tubular water turbine in which the length of the suction pipe is shortened to the extent that separation does not occur, and the area ratio of the suction pipe is six times smaller.

[Key points of the invention]

The present invention achieves the above object by bending the suction pipe double into an S-shape and inverting the first bent part on the upstream side to the second bent part on the downstream side.
In the S-type tubular water turbine having a bent portion, the first bent portion of the suction pipe and the discharge channel are 3≦≠≦6. This can be achieved by setting the area ratio A'fL between the inlet and outlet of the suction pipe to 4≦AR≦8. In addition, the position where the first bent part is communicated is preferably on the inside of the curve in the latter half of the bend, and it is more preferable that the communication pipe is disposed outside the suction pipe and provided with a valve or throttle that can adjust the flow rate inside the pipe.

That is, since separation occurs when low-energy fluid gathers on the inner wall of the bend due to the secondary flow within the first bend, the separation can be eliminated by injecting a small amount of high-energy fluid into this position.

Furthermore, it is important to inject the high-energy fluid immediately after the peeling, since the amount of S formed and the point at which the tube peels off are limited to the inner wall of the bend at the center of the first bend.

Note that the pressure in the diffuser increases as it goes downstream.

Therefore, in order to inject the high pressure (high energy) (5) water at the outlet of the suction pipe into the low pressure separation section upstream of the suction pipe, all that is required is piping and no power equipment is required.

In addition, when a large amount of water is injected, the kinetic energy at the outlet of the suction pipe increases, so it is preferable to attach a regulating valve or throttle to the pipe so that the amount of water injected can be adjusted to 15 times less than the flow rate of the water turbine.

In other words, this invention is an S-type tubular water turbine in which the area ratio can be increased as long as the suction pipe is long, but the length of the suction pipe is shortened to prevent separation while increasing the area ratio and improving performance.

[Embodiments of the invention]

The present invention will be explained below with reference to drawings showing embodiments.

FIG. 1 shows a sectional view of an S-type tubular water turbine according to the present invention. In the figure, the water wheel installed in the waterway includes an outer casing 2, an inner casing 4 supported by stay vanes 3 on the outer casing 2, a runner 5 supported by the inner casing 4, and an upstream side of the runner 5. The guide vane 6 adjusts the amount of water in the waterway and shuts it off using a mechanism that does not
The suction pipe 7 is bent double in an S-shape, and the water wheel shaft 8 passes through this S-shaped suction pipe 7 to form the water turbine 1.
The generator 9 is connected to a generator 9 installed on the downstream side of the generator. Note that the S-shaped suction pipe 7 has a first bent portion 7a on the upstream side and a second bent portion 7b that reverses the first bent portion 7a on the downstream side. 8 is the spillway.

The above is the same as the known S-type tubular water turbine, but in addition to the above, this invention connects the inner side of the second half of the bend of the first bent portion 7a of the suction pipe and the vicinity of the outlet 7c of the suction pipe to the pipe 9.
This pipe 9VC communicates with the outside of the waterway, and is further provided with a valve 10 that can adjust the flow rate within the pipe.

With the above configuration, high-pressure water near the outlet of the suction pipe flows backward through the pipe 9 and is injected into the separation area 7d of the water flow in the suction pipe, thereby suppressing the separation phenomenon. This injection water erosion is preferably less than 15 times the channel water flow, and can be adjusted by the valve 10.

〔Effect of the invention〕

(7) The S-shaped tubular water turbine according to the present invention aims to improve the efficiency of the turbine by suppressing the separation phenomenon by injecting high-pressure water on the outlet side of the discharge pipe into the separation area of the water flow in the S-shaped suction pipe. Furthermore, the length of the suction tube can be shortened without causing water flow separation within the suction tube, and the area ratio between the inlet and the outlet of the suction tube can be increased.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an S-type tubular water turbine according to the present invention.
Figures 2 and 3 show characteristic diagrams of a conventional S-type tubular water turbine, respectively. Figure 2 is a flow rate-efficiency characteristic diagram, and Figure 3 is a flow velocity diagram of a cross-section of the second half of the first bend of the suction pipe. It is. ■... Water turbine, 2... Outer casing, 3... Stay vane, 4... Inner casing, 5... Runner,
6... Guide vane, 7... Suction pipe, 7a...
1st bent part, 7b...2nd bent part, 7c...near the suction pipe outlet, 7d...separation area, 8...discharge channel, 9...
・Pipe, 10... Valve, V/Vm... Axial velocity ratio (
Flow velocity/axial direction of suction pipe inlet”; IT diagram a waste amount (%) f2 genius 3 songs

Claims (1)

[Scope of Claims] 1) In an S-shaped tubular water turbine having a suction pipe doubled in an S-shape and having a first bent part on the upstream side and a second bent part reversed to the second bent part on the downstream side, The first bent part and the vicinity of the outlet of the discharge channel or the suction pipe are communicated outside the water channel, and the ratio of the horizontal length L of the suction pipe to the runner diameter is set to 3≦%≦6.
and an S-type tubular water turbine characterized in that the area ratio AR between the inlet and outlet of the suction pipe is 4≦8≦8K. 2. The S-type tubular water turbine according to claim 1, wherein the position where the first bending portion is communicated is on the inner side of the rear half of the bend. 3) The S-type tubular water turbine according to claim 1 or 2, characterized in that the communicating pipe is provided with a button outside the suction pipe, and the limb pipe is provided with a valve or throttle for adjusting the flow rate inside the pipe. S type tubular water turbine.