JP2021179183A - Runner cone and hydraulic machine - Google Patents

Abstract

To reduce water pressure pulsation.SOLUTION: A runner cone is provided at the center part of a runner which is rotationally driven around a rotation axis by inflowing water. The runner cone comprises a cylindrical part formed in a cylindrical shape extending in a direction along the rotation axis, and a plurality of slits provided in the cylindrical part, the plurality of slits extending from the downstream end of the cylindrical part.SELECTED DRAWING: Figure 2

Description

Embodiments of the present invention relate to runner cones and hydraulic machines.

In recent years, equipment stability has been emphasized in the operation of hydraulic machines, and there is a demand for low vibration of hydraulic machines. The vibration in the hydraulic machine is mainly due to the pressure pulsation (hydraulic pulsation) in the flow path of the hydraulic machine. It is generally known that hydraulic pulsation is generated by the swinging spiral vortex generated on the downstream side of the runner. In order to reduce the vibration of hydraulic machines, it is desirable to reduce this hydraulic pulsation.

Japanese Unexamined Patent Publication No. 2011-247160 Japanese Unexamined Patent Publication No. 2009-115061 Japanese Unexamined Patent Publication No. 2013-234621

It is an object of the present invention to provide a runner cone and a hydraulic machine capable of reducing hydraulic pulsation.

The runner cone according to the embodiment is provided in the center of the runner which is rotationally driven around the rotation axis by the inflowing water. The runner cone includes a cylindrical portion formed in a cylindrical shape extending in a direction along the rotation axis, and a plurality of slits provided in the cylindrical portion, which are a plurality of slits extending from the downstream end of the cylindrical portion.

Further, the hydraulic machine according to the embodiment includes a runner having a crown, a band, and a plurality of runner blades provided between the crown and the band, and the above-mentioned runner cone provided in the center of the crown. , Equipped with.

According to the present invention, hydraulic pulsation can be reduced.

FIG. 1 is a cross-sectional view of the meridional surface of a Francis turbine according to an embodiment. FIG. 2 is a schematic front view of the runner cone of FIG. FIG. 3 is a front sectional view of the runner cone of FIG. FIG. 4 is a cross-sectional view taken along the line AA of FIG. FIG. 5 is a diagram for explaining the generation of a spiral vortex in a general Francis turbine. FIG. 6 is a cross-sectional view showing a modified example (first modified example) of FIG. FIG. 7 is a front sectional view showing a modified example (second modified example) of FIG. FIG. 8 is a cross-sectional view taken along the line BB of FIG. FIG. 9 is a front sectional view showing a modified example (third modified example) of FIG.

Hereinafter, the runner cone and the hydraulic machine according to the present embodiment will be described with reference to the drawings. Here, first, a Francis turbine, which is an example of a hydraulic machine, will be described with reference to FIG.

As shown in FIG. 1, the Francis turbine 1 includes a spiral casing 2 in which water flows from an upper pond through a penstock (none of which is shown) during operation of the turbine, a plurality of stay vanes 3, and a plurality of guides. It has a vane 4, a runner 5, and a runner cone 20.

The stay vane 3 is configured to guide the water flowing into the casing 2 to the guide vane 4 and the runner 5, and is arranged at a predetermined interval in the circumferential direction. A flow path through which water flows is formed between the stay vanes 3.

The guide vanes 4 are configured to guide the inflowing water to the runner 5, and are arranged at predetermined intervals in the circumferential direction. A flow path through which water flows is formed between the guide vanes 4. Each guide vane 4 is configured to be rotatable, and the flow rate of water flowing into the runner 5 can be adjusted by rotating each guide vane 4 to change the opening degree. In this way, the amount of power generated by the generator 7, which will be described later, can be adjusted.

The runner 5 is configured to be rotatable about the rotation axis X with respect to the casing 2. The runner 5 is rotationally driven in the rotation direction R about the rotation axis X by the water flowing from the casing 2 during operation of the water turbine. That is, the runner 5 converts the pressure energy of the water flowing into the runner 5 into rotational energy. The runner 5 has a crown 9 connected to the main shaft 6, a band 10 provided on the outer peripheral side of the crown 9, and a plurality of runner blades 11 provided between the crown 9 and the band 10. There is. The runner blades 11 are arranged at predetermined intervals in the circumferential direction, and are joined to the crown 9 and the band 10, respectively. A flow path (inter-blade flow path) through which water flows is formed between the runner blades 11. Further, a runner cone 20, which will be described later, is provided at the center of the crown 9.

A generator 7 is connected to the runner 5 via a spindle 6. The generator 7 is configured to generate electricity by transmitting the rotational energy of the runner 5 when the water turbine is operated.

A suction pipe 8 is provided on the downstream side of the runner 5 when the water turbine is operated. The suction pipe 8 is connected to a lower pond or a drainage channel (not shown), and the water obtained by rotationally driving the runner 5 recovers the pressure and is discharged to the lower pond or the drainage channel.

The generator 7 also has a function as an electric motor, and may be configured to rotationally drive the runner 5 by supplying electric power. In this case, the water in the lower pond can be sucked up through the suction pipe 8 and discharged to the upper pond, and the Francis turbine 1 can be pumped (pumped) as a pump turbine. At this time, the opening degree of the guide vane 4 is changed so as to have an appropriate pumping amount according to the pump head.

Next, the runner cone 20 according to the present embodiment will be described with reference to FIGS. 2 to 4.

As shown in FIG. 2, the runner cone 20 includes a truncated cone portion 22 formed in a truncated cone shape, a cylindrical portion 24 formed in a cylindrical shape, and a plurality of slits 26 provided in the cylindrical portion 24. ing.

As shown in FIG. 2, the truncated cone portion 22 is formed in a truncated cone shape so that the outer diameter becomes smaller toward the downstream side (lower side in FIG. 2). The upstream end 22a of the truncated cone portion 22 is connected to the central portion of the crown 9 via the connecting portion 21. The truncated cone portion 22 is fixed to the crown 9 by bolts or the like. As a result, the runner cone 20 also rotates with the rotation of the runner 5. The downstream end 22b of the truncated cone portion 22 is connected to the upstream end 24a of the cylindrical portion 24 described later.

As shown in FIG. 3, the truncated cone portion 22 is formed to be hollow. As shown, the inner diameter of the upstream end 22a of the truncated cone 22 may be smaller than the inner diameter of the downstream end 22b of the truncated cone 22. In this case, the inner peripheral surface of the truncated cone portion 22 is an inner wall surface 22c extending from the upstream end 22a in the direction along the rotation axis X of the runner 5, and an inner wall surface extending from the downstream end 22b in the direction along the rotation axis X of the runner 5. 22d and may be included. Further, the inner wall surface 22c and the inner wall surface 22d may be connected by a step 22e. The truncated cone portion 22 is arranged so that the center line of the truncated cone portion 22 coincides with the rotation axis X of the runner 5.

As shown in FIG. 2, the cylindrical portion 24 extends in a direction along the rotation axis X of the runner 5. As described above, the upstream end 24a of the cylindrical portion 24 is connected to the downstream end 22b of the truncated cone portion 22. That is, the cylindrical portion 24 extends downstream from the downstream end 22b of the truncated cone portion 22 along the rotation axis X of the runner 5. The outer diameter at the upstream end 24a of the cylindrical portion 24 may be equal to the outer diameter at the downstream end 22b of the truncated cone portion 22.

As shown in FIG. 3, the cylindrical portion 24 is formed to be hollow. As shown, the inner diameter of the upstream end 24a of the cylindrical portion 24 may be equal to the inner diameter of the downstream end 24b of the cylindrical portion 24. In this case, the inner peripheral surface 24d of the cylindrical portion 24 may extend from the upstream end 24a to the downstream end 24b along the rotation axis X of the runner 5. Further, the inner diameter of the upstream end 24a of the cylindrical portion 24 may be equal to the inner diameter of the downstream end 22b of the truncated cone portion 22. The cylindrical portion 24 is arranged so that the center line of the cylindrical portion 24 coincides with the rotation axis X of the runner 5.

The truncated cone portion 22 and the cylindrical portion 24 may be joined by welding or the like, but may be integrally formed seamlessly.

As shown in FIG. 2, the dimension L of the cylindrical portion 24 in the direction along the rotation axis X of the runner 5 is 0.04 times or more and 0.38 times or less the outlet diameter E of the runner 5 (see FIG. 1). May be good. Further, the outer diameter (diameter) D of the cylindrical portion 24 may be 0.16 times or more and 0.38 times or less the outlet diameter E of the runner.

As shown in FIGS. 2 to 4, a plurality of slits 26 are provided in the cylindrical portion 24. The slit 26 extends from the downstream end 24b of the cylindrical portion 24. As shown in FIGS. 2 and 3, the slit 26 may extend in a direction along the rotation axis X of the runner 5. Further, each slit 26 may extend so as to be parallel to each other. As shown in FIG. 4, the slit 26 penetrates from the outer peripheral surface 24c of the cylindrical portion 24 to the inner peripheral surface 24d. As shown in FIG. 4, the slit 26 may be oriented in the radial direction when viewed in the direction along the rotation axis X of the runner 5. That is, the center line of the slit 26 may extend in the radial direction. Further, the slits 26 may be arranged at equal intervals in the circumferential direction.

As shown in FIG. 2, the dimension S of the slit 26 in the direction along the rotation axis X of the runner 5 is 0.3 times or more and 1.0 times the dimension L of the cylindrical portion 24 in the direction along the rotation axis X of the runner 5. It may be as follows. Further, as shown in FIGS. 2 and 4, the dimension T of the slit 26 in the circumferential direction of the outer peripheral surface 24c of the cylindrical portion 24 is 0.05 times or more and 0.3 times the peripheral length of the outer peripheral surface 24c of the cylindrical portion 24. It may be as follows.

Next, the operation and effect of the present embodiment having such a configuration will be described.

When the Francis turbine 1 according to the present embodiment is operated, water flows into the guide vane 4 from the upper pond (not shown) through the penstock, the casing 2 and the stay vane 3, and the water flows from the guide vane 4 into the runner 5. do. The runner 5 is rotationally driven by the water flowing into the runner 5. The rotary drive runner 5 transmits rotational energy to the generator 7 via the connected spindle 6, and the generator 7 generates electricity. After that, the water flows in from the runner 5 and is discharged to a lower pond (not shown) through the suction pipe 8.

The water flowing into the runner 5 flows along the runner blade 11 from the inlet side to the outlet side during operation of the turbine. During this time, the pressure on the pressure surface of the runner blade 11 is increased by the flow of water, and the runner 5 is rotated in the rotation direction R. Along with the rotation of the runner 5, the runner cone 20 also rotates in the rotation direction R.

Here, since the runner blade 11 is fixed to the crown 9 and the band 10, when the opening degree of the guide vane 4 is changed to adjust the flow rate, the inflow angle of water to the runner blade 11 changes. do. In this case, a part of the fluid energy of the water flow is not converted into rotational energy, and as a result, a swirling flow may occur on the downstream side of the runner 5.

In a general Francis turbine, a spiral vortex may be generated on the downstream side of the runner 5 due to this swirling flow. More specifically, when the operation is performed at a flow rate lower than the flow rate at the design point, that is, the partial load operation is performed, the flow rate is small. Therefore, on the downstream side of the runner 5, as shown in FIG. The flow is biased to the outer outer region A, and the flowing water flows while swirling around the outer region A at high speed. At this time, the central region B in the central portion of the flow path becomes almost a dead water region. Therefore, a spiral vortex can be generated by the shearing force generated by the velocity difference between the outer region A and the central region B. This spiral vortex swings in the same direction as the rotation direction R of the runner 5.

On the other hand, even when the operation is performed at a flow rate higher than the flow rate at the design point, that is, the overload operation is performed, the flow velocity is high because the flow rate is large, and a spiral vortex is likely to be generated on the downstream side of the runner 5. In particular, in the case of a high-head turbine, since the flow rate is relatively small even in overload operation, the flow is biased to the outer region A on the downstream side of the runner 5, as shown in FIG. Therefore, a spiral vortex core is generated in the central region B, and a larger spiral vortex can be generated due to the development of the pressure gradient in the spiral core. This spiral vortex swings in the direction opposite to the rotation direction R of the runner 5.

Such a spiral vortex may generate a strong hydraulic pulsation, hit the wall surface of the suction pipe 8 violently, and cause resonance with other equipment or structures of the power plant. This causes vibration and noise in the power plant, which can affect stable operation.

On the other hand, according to the present embodiment, the runner cone 20 provided at the center of the runner 5 includes a cylindrical portion 24 formed in a cylindrical shape extending in a direction along the rotation axis X of the runner 5. As a result, the cylindrical portion 24 of the runner cone 20 can enter the central region B, which is a dead water area. Therefore, during the partial load operation, the rotation of the runner cone 20 can impart a turning speed component to the central region B, and the speed difference between the outer region A and the central region B can be reduced. As a result, the generation of spiral vortices can be suppressed. Further, during the overload operation, the development of the pressure gradient in the vortex core of the spiral vortex can be suppressed by imparting the swirling speed component to the central region B. As a result, the generation of spiral vortices can be suppressed. As described above, in the operating range from the partial load operation to the overload operation, the generation of the spiral vortex can be suppressed and the hydraulic pulsation can be reduced.

In particular, according to the present embodiment, the cylindrical portion 24 is provided with a plurality of slits 26 extending from the downstream end 24b. As a result, the resistance of the runner cone 20 during rotation can be increased by allowing water to enter the slit 26. Therefore, during the partial load operation, a larger turning speed component can be applied to the central region B, and the speed difference between the outer region A and the central region B can be further reduced. As a result, the generation of spiral vortices can be suppressed more effectively. Further, during the overload operation, the development of the pressure gradient in the vortex core of the spiral vortex can be more effectively suppressed by imparting a larger turning speed component to the central region B. As a result, the generation of spiral vortices can be suppressed more effectively. Further, since a plurality of slits 26 are provided in the cylindrical portion 24, small-scale vortices are induced in advance from each slit 26, but these vortices have the same rotation direction. They can cancel each other out and suppress the development of large-scale vortices. As described above, in the operating range from the partial load operation to the overload operation, the generation of the spiral vortex can be suppressed more effectively, and the hydraulic pulsation can be further reduced.

Further, according to the present embodiment, the dimension L of the cylindrical portion 24 in the direction along the rotation axis X of the runner 5 is 0.04 times or more and 0.38 times or less the outlet diameter E of the runner 5, and the cylindrical portion. The diameter D of 24 is 0.16 times or more and 0.38 times or less of the outlet diameter E of the runner 5. By setting the dimension L and the diameter D of the cylindrical portion 24 within such a range, the turning speed component can be more effectively imparted to the central region B. Therefore, the generation of spiral vortices can be suppressed more effectively, and the hydraulic pulsation can be further reduced.

Further, according to the present embodiment, the dimension S of the slit 26 in the direction along the rotation axis X of the runner 5 is 0.3 times or more the dimension L of the cylindrical portion 24 in the direction along the rotation axis X of the runner 5. It is 0.0 times or less. By setting the dimension S of the slit 26 within such a range, it is possible to impart a larger turning speed component to the central region B in a wide range in the direction along the rotation axis X of the runner 5. Further, the dimension T of the slit 26 in the circumferential direction of the outer peripheral surface 24c of the cylindrical portion 24 is 0.05 times or more and 0.3 times or less the peripheral length of the outer peripheral surface 24c of the cylindrical portion 24. By setting the dimension T of the slit 26 within such a range, the turning speed component can be more effectively imparted to the central region B.

(First modification)
In the above-described embodiment, an example is shown in which the slit 26 faces the radial direction when viewed in the direction along the rotation axis X of the runner 5 (see FIG. 4). However, the present invention is not limited to this, and as shown in FIG. 6, the slit 26 may be inclined with respect to the radial direction when viewed in the direction along the rotation axis X of the runner 5.

That is, as shown in FIG. 6, the center line C of the slit 26 may have an inclination angle α with respect to the radial direction. The inclination angle α may be 15 degrees or more and 45 degrees or less. As shown in the figure, each slit 26 may be tilted at the same tilt angle α with respect to the radial direction. However, the present invention is not limited to this, and each slit 26 may be tilted at a different inclination angle as long as it is within the above numerical range. Further, in the example shown in FIG. 6, the slit 26 is inclined in the direction opposite to the rotation direction R of the runner 5 (clockwise in FIG. 6), but the slit 26 is the rotation direction R of the runner 5. It may be tilted counterclockwise in FIG.

According to this modification, since the slit 26 is inclined with respect to the radial direction, the strength of the turning speed component applied to the central region B, which is a dead water region, can be adjusted. That is, by inclining the slit 26 in the direction opposite to the rotation direction R of the runner 5, the resistance of the runner cone 20 at the time of rotation can be increased. This makes it possible to impart a larger turning speed component to the central region B. Therefore, the generation of spiral vortices can be suppressed more effectively, and the hydraulic pulsation can be further reduced. Further, by inclining the slit 26 in the rotation direction R of the runner 5, the resistance of the runner cone 20 during rotation can be reduced. This makes it possible to suppress a decrease in the rotational efficiency of the runner 5.

(Second modification)
Further, in addition to the configuration of the above-described embodiment, as shown in FIGS. 7 and 8, the runner cone 20 may further include a protruding portion 27 protruding from the outer peripheral surface 24c of the cylindrical portion 24. The protrusion 27 according to this modification extends in the direction along the rotation axis X of the runner 5.

That is, as shown in FIGS. 7 and 8, the protruding portion 27 is provided on the outer peripheral surface 24c of the cylindrical portion 24 so as to protrude from the outer peripheral surface 24c of the cylindrical portion 24. As shown in FIG. 7, the protrusion 27 may extend so as to be parallel to the slit 26. The protrusion 27 may extend from the downstream end 24b to a portion on the upstream end 24a side of the slit 26. As shown in FIG. 8, the protruding portion 27 may be formed in a thin plate shape having two main surfaces in the circumferential direction.

Further, as shown in FIGS. 7 and 8, a plurality of projecting portions 27 may be provided on the outer peripheral surface 24c of the cylindrical portion 24. As shown in FIG. 7, each protrusion 27 may extend so as to be parallel to each other. Further, as shown in FIG. 8, the projecting portions 27 may be arranged at equal intervals in the circumferential direction, and may be arranged one by one between the slits 26.

According to this modification, the resistance of the runner cone 20 during rotation can be increased by providing the protruding portion 27 on the outer peripheral surface 24c of the cylindrical portion 24. This makes it possible to impart a larger turning speed component to the central region B. Therefore, the generation of spiral vortices can be suppressed more effectively, and the hydraulic pulsation can be further reduced. Further, in the overload operation, a peeling vortex is generated due to the separation of the flow at the protrusion 27 when the runner cone 20 is rotated, and the development of the pressure gradient of the vortex core of the spiral vortex can be suppressed by this separation vortex. Therefore, it is possible to more effectively suppress the generation of spiral vortices and further reduce the hydraulic pulsation, especially during overload operation.

(Third modification example)
Further, in addition to the configuration of the above-described embodiment, as shown in FIG. 9, the runner cone 20 may further include a protruding portion 28 protruding from the outer peripheral surface 24c of the cylindrical portion 24. The protruding portion 28 according to this modification is formed in a spiral shape extending in a direction opposite to the rotation direction R of the runner 5 toward the downstream end 24b of the cylindrical portion 24.

That is, as shown in FIG. 9, the protruding portion 28 is provided on the outer peripheral surface 24c of the cylindrical portion 24 so as to be wound in the direction opposite to the rotation direction R of the runner 5 from the upstream end 24a to the downstream end 24b. Has been done. As shown in FIG. 9, when viewed from the front of the runner cone 20, the protrusion 28 may have an inclination angle of 15 degrees or more and 45 degrees or less with respect to the radial direction (horizontal direction in FIG. 9). .. The protrusion 28 may be formed in a thin plate shape having two main surfaces in the circumferential direction.

According to this modification, by providing the spiral protrusion 28 on the outer peripheral surface 24c of the cylindrical portion 24, in addition to the turning speed component, the downstream side in the axial direction (lower side in FIG. 9) is provided in the central region B. It is possible to impart a velocity component toward. As a result, a flow can be generated in the central region B, and the dead water area can be reduced. Therefore, the generation of spiral vortices can be suppressed more effectively, and the hydraulic pulsation can be further reduced. Further, during overload operation, a tip vortex is generated at the end of the protrusion 28 when the runner cone 20 is rotated, and the tip vortex can suppress the development of the pressure gradient of the vortex core of the spiral vortex. Therefore, it is possible to more effectively suppress the generation of spiral vortices and further reduce the hydraulic pulsation, especially during overload operation.

(Other variants)
Further, in the above-described embodiment, an example is shown in which the runner cone 20 includes a truncated cone portion 22 formed in a truncated cone shape (see FIG. 2). However, the present invention is not limited to this, and the runner cone 20 may not be provided with the above-mentioned truncated cone portion 22. In this case, the upstream end 24a of the cylindrical portion 24 may be connected to the central portion of the crown 9.

Further, in the above-described embodiment, an example is shown in which the slit 26 extends in the direction along the rotation axis X of the runner 5 (see FIG. 2). However, the present invention is not limited to this, and the slit 26 may be inclined with respect to the rotation axis X of the runner 5. That is, the slit 26 may extend in a direction intersecting the rotation axis X of the runner 5.

Further, in the above-mentioned second modification, an example is shown in which the protruding portion 27 extends in the direction along the rotation axis X of the runner 5 (see FIG. 7). However, the present invention is not limited to this, and the protrusion 27 may be inclined with respect to the rotation axis X of the runner 5. That is, the protrusion 27 may extend in a direction intersecting the rotation axis X of the runner 5.

Even in such a case, it is possible to suppress the generation of spiral vortices and reduce the hydraulic pulsation in the operating range from the partial load operation to the overload operation.

According to the embodiment described above, the hydraulic pulsation can be reduced.

Although embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1: Francis turbine, 5: runner, 9: crown, 10: band, 11: runner blade, 20: runner cone, 24: cylindrical part, 24b: downstream end, 26: slit, 27, 28: protrusion, R: rotation Direction, X: Rotation axis

Claims (9)

It is a runner cone provided in the center of the runner that is rotationally driven around the rotation axis by the inflowing water.
A cylindrical portion formed in a cylindrical shape extending in the direction along the rotation axis, and a cylindrical portion.
A runner cone comprising a plurality of slits provided in the cylindrical portion, the plurality of slits extending from the downstream end of the cylindrical portion. The runner cone according to claim 1, wherein the slit extends in a direction along the rotation axis. The size of the cylindrical portion in the direction along the rotation axis is 0.04 times or more and 0.38 times or less the outlet diameter of the runner, and the diameter of the cylindrical portion is 0.16 times the outlet diameter of the runner. The runner cone according to claim 1 or 2, which is 0.38 times or more. The dimension of the slit in the direction along the rotation axis is 0.3 times or more and 1.0 times or less the dimension of the cylinder portion in the direction along the rotation axis, and the dimension in the circumferential direction of the outer peripheral surface of the cylinder portion. The runner cone according to any one of claims 1 to 3, wherein the dimension of the slit is 0.05 times or more and 0.3 times or less the peripheral length of the outer peripheral surface of the cylindrical portion. The runner cone according to any one of claims 1 to 4, wherein the slit is inclined with respect to the radial direction when viewed in a direction along the rotation axis. The runner cone according to any one of claims 1 to 5, further comprising a protruding portion protruding from the outer peripheral surface of the cylindrical portion. The runner cone according to claim 6, wherein the protruding portion extends in a direction along the rotation axis. The runner cone according to claim 6, wherein the protruding portion is formed in a spiral shape extending in a direction opposite to the rotation direction of the runner toward the downstream end of the cylindrical portion. A runner having a crown, a band, and a plurality of runner blades provided between the crown and the band.
The hydraulic machine provided with the runner cone according to any one of claims 1 to 8 provided in the center of the crown.

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