JPH0718399B2 - Turbine flow adjustment structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reaction turbine such as a Francis turbine, a propeller turbine, and a mixed flow turbine, and more particularly to a flow rate adjusting structure capable of maintaining optimum efficiency regardless of the flow rate.

[0002]

2. Description of the Related Art Water turbines used for power generation and the like are roughly classified into reaction type and impulse type. Impulsive turbines include Pelton turbines, Targo impulse turbines and cross-flow turbines. The advantage is that the jet of water acts directly on the runner, so almost all the water can be used effectively and the flow rate decreases. However, the efficiency does not decrease so much.

On the other hand, reaction turbines such as Francis turbines, propeller turbines, and mixed-flow turbines have much higher hydraulic energy conversion efficiency and larger specific speed than impulsive turbines, and therefore can be miniaturized. Further, since the runner rotates in water, the head from the installation surface of the water turbine to the discharge surface can be recovered from the suction pipe downstream of the runner, and the water head can be effectively used. In the case of the impulse type, a vertical structure may not be available in some cases, whereas in the reaction type, both a vertical type structure and a horizontal type structure can be adopted, which is a big difference.

As described above, the reaction type and the impulse type water turbines have a relationship in which they have advantages and disadvantages in terms of efficiency and structure. For example, when designing the design flow rate value, the reaction turbine has a higher value than the impulse turbine in terms of efficiency, whereas the impulse turbine reversely reacts when operated at a flow rate outside the design flow value. It is more efficient than a water mill.

[0005]

In the reaction type water turbine, a plurality of guide vanes for adjusting the flow rate are provided between the water intake port and the runner. These guide vanes change their postures in conjunction with each other, and the amount of water supplied to the runner is adjusted by widening or narrowing the flow path between adjacent guide vanes.

However, in the flow rate adjustment by the guide vanes, high efficiency can be obtained when the guide vanes are set at the inflow angle determined with respect to the design flow rate. On the other hand, when the flow rate is smaller than the design flow rate, the attitude of the guide vanes is changed so that the flow path is narrowed, so that the inflow angle of water is also reduced. For this reason, the inflow angle due to the guide vanes deviates from the designed value, and the inflow angle of water into the runner changes, resulting in a significant decrease in efficiency. Also,
When the flow rate is larger than the design flow rate, the guide vanes are set in such a posture that the inflow angle becomes large, and similarly, the value becomes lower than the efficiency at the design flow rate.

Further, when the guide vanes are incorporated into the casing, it is necessary to provide a clearance between the inner wall of the casing and the end surface of the guide vanes so that the guide vanes can move.

However, the water is supplied from this clearance toward the runner, and the flow of the supplied water is disturbed by the inflow angle set by the guide vanes. For this reason, it affects the flow of water having an optimum incident angle to the runner with respect to the set flow rate, which causes a decrease in efficiency. In particular, when the flow rate is low, the amount of water flowing from the clearance to the runner occupies a high proportion of the total flow rate, so that the efficiency is significantly reduced.

As described above, the reaction type and impulse type water turbines have many inadequate points in order to be able to operate with high efficiency against changes in the flow rate.

The problem to be solved in the present invention is to provide a flow rate adjusting structure which can always operate with high efficiency even if the amount of supplied water changes.

[0011]

According to the present invention, in a reaction type water turbine having a guide vane in a flow path from a casing to an inside where a runner is housed, the guide vane has an optimum inflow angle with respect to the runner. A flow rate adjusting ring that is integrally fixed to the inner wall of the flow channel and that crosses the flow channel between the guide vane and the runner is disposed so as to be movable coaxially with the runner, and the flow rate adjusting ring moves in the axial direction. The flow passage area of the flow passage extending from the guide vane to the runner is made variable.

[0012]

Since the guide vanes that give the optimum inflow angle to the runner are fixed and the flow passage area is changed by the movement of the flow rate adjusting ring, the inflow angle by the guide vanes does not change even if the flow passage is arbitrarily changed. Therefore, the inflow angle is maintained at an optimum value regardless of the flow rate value, and a highly efficient output can be obtained as compared with the conventional structure in which the attitude of the guide vanes is changed to adjust the flow rate.

Further, by integrating the guide vanes with the inner wall of the flow path, the gap between the vane and the inner wall is eliminated, and the generation of the flow that disturbs the streamline due to the guide vane is prevented.

[0014]

1 is a longitudinal sectional view showing a main part of a Francis turbine equipped with a flow rate adjusting structure of the present invention, and FIG. 2 is a transverse sectional view taken along the line AA of FIG. Further, FIG. 3 is a perspective view showing each member in an exploded manner except for the casing.

In the figure, a spiral casing 3 is incorporated between an upper cover 1 and a lower cover 2, and the upper cover 1, the lower cover 2 and the casing 3 are coaxially and integrally connected to each other. And the upper and lower covers 1,
A runner 4 is rotatably arranged in an internal space formed by 2, and an output shaft 4a thereof projects from the upper cover 1 to the outside.

The casing 3 is integrated by communicating its internal flow path into the upper and lower covers 1 and 2, and is provided with a plurality of stay vanes 3a corresponding to the position of the runner 4.

The upper cover 1 has these stay vanes 3
A plurality of guide vanes 1a is provided at a position inside a and surrounding the runner 4. These guide vanes 1
All of a are integrated with the upper cover 1 and are fixed in the posture shown in FIG. Then, the inflow angle α of water from the casing 3 determined by the attitude of the guide vane 1 a is set to a value that provides the optimum incident angle with respect to the runner 4.

The lower cover 2 has a flange 2a at one end,
The other end surface is arranged so as to abut against the tip surface of the guide vane 1a. As a result, the water from the casing 3 is removed from the lower cover 2
A flow path structure can be obtained which is supplied to the runner 4 side through the guide vanes 1a partitioned by.

In the upper and lower covers 1 and 2, a flow rate adjusting ring 5 which is movable coaxially is incorporated. This flow rate adjusting ring 5
As shown in FIG. 3, it has a hollow cylindrical sleeve 5a and a double tubular flange 5b at one end thereof. The outer peripheral surface of the sleeve 5a is watertightly connected to the inner peripheral surface of the lower cover 2 and is slidable in the axial direction.
Further, a slit 5c into which the guide vane 1a formed integrally with the upper cover 1 is inserted is provided on the end surface of the flange 5b. As shown in FIG. 2, these slits 5c have a shape that is substantially equal to the cross-sectional shape of the guide vane 1a and the clearance is as small as possible. Due to the relationship between the slit 5c and the guide vane 1a, the flow rate adjusting ring 5 can be moved in the axial direction with respect to the fixed guide vane 1a and its position can be arbitrarily changed.

Incidentally, in order to reduce the resistance of water when moving the flow rate adjusting ring 5, an appropriate number of holes 5e are formed in the flange 5b. These holes 5e allow water to flow in and out when the flow rate adjusting ring 5 moves, thereby reducing the resistance. Further, an outer sleeve 5f is provided on the outer peripheral edge of the flange 5b coaxially with the sleeve 5a,
The outer sleeve 5f can be slid between the casing 3 and the lower cover 2 via a packing 5g.

In order to move the flow rate adjusting ring 5 in its axial direction, a cylinder 7 is incorporated between the lower cover 2 and the draft tube 6 provided below it. This cylinder 7
Around the sleeve 5a of the flow rate adjusting ring 5, both ends in the axial direction thereof are respectively covered with the lower cover 2 and the draft tube 6.
It is connected to. Then, two ports 7a, 7b communicating with an external hydraulic pressure source P using, for example, a pump or the like are opened in the peripheral wall, and the working fluid can be supplied and discharged through these ports 7a, 7b.

On the other hand, the piston 8 is fixed to the outer periphery of the sleeve 5a of the flow rate adjusting ring 5 by a lock nut 8b,
The packing 8a provided on the outer peripheral surface of the cylinder 7 can be closely attached to the inner peripheral surface of the cylinder 7. Therefore, if the hydraulic pressure source P is operated to supply hydraulic fluid to the port 7a side and drain the hydraulic fluid from the chamber on the port 7b side, as shown in the right half of FIG. As a result, the piston 8 rises, and the flow rate adjusting ring 5 also moves upward. Conversely, if hydraulic oil is supplied from the port 7b side and the hydraulic fluid is discharged from the chamber on the port 7a side, as shown in the left half of FIG.
Goes down.

In the above structure, when the flange 5b is lowered until it abuts the upper end of the lower casing 2 as shown in the left half of FIG. The maximum flow rate of water is supplied to the 4th side. When the hydraulic pressure source P is operated to raise the piston 8 in the cylinder 7, the flow rate adjusting ring 5
The guide vane 1a comes into the slit 5c. Therefore, the flow path around the guide vane 1a is narrowed in the axial direction by the flange 5b of the flow rate adjusting ring 5, and the amount of water supplied from the casing 3 is reduced.

In this way, by moving the flow rate adjusting ring 5 in the axial direction, the casing 3 and the runner 4 are moved.
The flow rate to the side can be changed. That is, in the conventional structure, the overall flow rate is changed by the operation of changing the attitude of the guide vane 1a, but the guide vane 1a is fixed and always maintains the same attitude, and the flow passage area due to the movement of the flow rate adjusting ring 5 is changed. Change the total flow rate by changing. Even if the flow rate is the maximum value and is reduced by reducing the flow rate value, the guide vane 1a has an optimum posture predesigned as shown in FIG. A streamline with the optimum value as designed can be obtained. Therefore, in the case of adjusting the flow rate by changing the attitude of the guide vane 1a, it is inevitable that the efficiency decreases due to the change of the inflow angle, but the operation can be always performed with high efficiency.

Further, since the upper end of the guide vane 1a in the axial direction is integrated with the upper cover 1 and the lower end is seated on the upper surface of the lower cover 2, the guide vane 1a and the upper and lower covers 1 and 2 are separated from each other. There is no gap between them. For this reason, the water from the casing 3 passes through only the flow path between the guide vanes 1a toward the runner 4, and becomes a streamline with a uniform inflow angle. Therefore, in the case where there is a gap between the movable vane and the cover as in the conventional movable guide vane, the leakage interferes with the flow of water guided by the guide vane, resulting in a decrease in efficiency. High efficiency can be maintained without the occurrence of such flow interference.

In this example, the guide vanes 1a are integrated with the upper cover 1, but instead of this, guide vanes are provided on the end faces of the lower cover 2 in the same arrangement, and these end faces are covered with the upper cover 1. Alternatively, the flow passage area around the guide vane may be changed by the flow rate adjusting ring 5 so that the assembly structure is configured to be seated at 1.

FIG. 4 is a vertical cross-sectional view of the essential part showing an example in which the movement of the flow rate adjusting ring 5 is changed to the hydraulic drive of the previous example and the chain is manually operated. The same members as those shown in FIGS. 1 to 3 are designated by the common reference numerals, and detailed description thereof will be omitted.

In the figure, the sleeve 5a of the flow rate adjusting ring 5 is shown.
A male screw 5d is engraved on the outer peripheral surface of and the sprocket 9 is screwed onto the male screw 5d. The sprocket 9 is a chain 9 driven by an external drive device or a manually operated handle.
It can be rotated by a. Further, the lower cover 2 has an annular collar 9b to which the sprocket 9 is connected.
And the sprocket 9 is rotatably supported by the collar 9b.

Also in this structure, when the sprocket 9 is rotated by the chain 9a, the sprocket 9 moves up and down in the figure. Then, since the sprocket 9 is supported by the collar 9b, the rotation of the sprocket 9 is not transmitted to the flow rate adjusting ring 5, and the flow rate adjusting ring 5 moves only in the axial direction thereof as in the previous example. Therefore,
If the position of the flow rate adjusting ring 5 is set to match the flow rate of water from the casing 3, highly efficient operation can be performed.

FIG. 5 is a vertical cross-sectional view of a main part in which a flow rate adjusting structure of the present invention is applied to a propeller or a Kaplan turbine as another example of a reaction turbine.

In this example, only the runner is different from that shown in FIGS. 1 to 3, and the other configurations are exactly the same.
That is, the runner 10 is of a propeller type, and the flow rate adjusting ring 5 is provided around the runner 10 so as to be vertically movable coaxially with the runner 10, and the flow rate adjusting ring 5 has its flange 5b portion operated by the operation of the hydraulic pressure source P. The flow rate area can be adjusted by changing the flow passage area around the guide vane 1a. The attitude of the guide vanes 1a is fixed to the optimum one at the design stage, and the runner 10 can be rotationally driven with high efficiency regardless of the magnitude of the flow rate.

[0032]

According to the present invention, water can be supplied to the runner side by the guide vanes that have a relationship with the runner having an optimum inflow angle regardless of the flow rate. For this reason, in a configuration in which the attitude of the guide vane is changed and the flow rate is changed like in the conventional reaction turbine, the efficiency is lowered due to the change in the flow rate, whereas the output with high efficiency is obtained even if the flow rate value is changed. To be

Further, since the guide vanes are fixed, there is no gap between the guide vanes and the inner wall of the cover, and there is no leak that disturbs the flow line of the flow due to the guide vanes. Therefore, the operation with even higher efficiency becomes possible by combining with the maintenance of the optimum inflow angle by the guide vanes.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part showing an example in which a flow rate adjusting structure of the present invention is applied to a Francis turbine.

2 is a cross-sectional view taken along the line AA of FIG.
It is a figure which shows arrangement | positioning of a guide vane and a slit.

FIG. 3 is an exploded perspective view showing each member except a casing.

FIG. 4 is a vertical cross-sectional view of a main part showing an example of an operation structure of a flow rate adjusting ring with a sprocket and a chain.

FIG. 5 is a vertical cross-sectional view of a main part of an example in which the flow rate adjusting structure of the present invention is applied to a propeller or Kaplan type turbine.

[Explanation of symbols]

 1 Upper cover 1a Guide vane 2 Lower cover 2a Flange 3 Casing 4 Runner 5 Flow rate adjusting ring 5a Sleeve 5b Flange 5c Slit 6 Draft tube 7 Cylinder 8 Piston 9 Sprocket 9a Chain 10 Runner

Claims (1)

[Claims] 1. A reaction type water turbine having a guide vane in a flow path from a casing to an inside where a runner is accommodated, wherein the guide vane has an optimum inflow angle with respect to the runner and is provided on an inner wall of the flow path. A flow rate adjusting ring, which is fixed integrally and traverses the flow path between the guide vane and the runner, is movably arranged coaxially with the runner, and is moved from the guide vane to the runner by moving the flow rate adjusting ring in the axial direction. A flow rate adjusting structure for a water turbine, characterized in that the flow passage area of the flow passage is variable.