JP2010043609A - Runner structure of hydraulic machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a runner structure which allows a shape of a runner cone to be freely designed, and suppresses occurrence and development of a whirl. <P>SOLUTION: The runner structure of hydraulic machinery consists of a main shaft 2, a runner blade 1a, a runner crown 1b, a runner vane 1c, and a runner cone 1d. The runner cone 1d is fastened by a joining means 8 which does not transmit rotation torque to the center of the runner crown 1b, or to the main shaft 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a runner structure of a hydraulic machine, and more particularly to a runner structure of a hydraulic machine in which a runner cone is attached to the downstream side of the runner.

  The runner of the hydraulic machine is a prime mover for generating electric power by rotating the energy generated by the water flowing in from upstream and transmitting the power generated at this time to the generator at the top of the runner. A runner structure of a conventional Francis type turbine suitable for use from a high head to a medium head will be described with reference to FIG. 8 (Patent Document 1).

  The runner 1 of the Francis type turbine transmits power from the main shaft 2 to the generator. Water from the upper pond (not shown) is guided to the casing 3 and rectified by the steven 4 and the guide vane 5 and flows into the runner 1. Water flowing out of the runner 1 flows into the upper suction pipe 6 and flows out to the lower pond through the suction pipe.

  The runner 1 includes a runner blade 1a for receiving a water flow, a runner crown 1b for connecting the main shaft 2 for supporting and fixing the runner blade 1a and transmitting power, a runner band 1c for fastening the runner blade 1a outside, The runner cone 1d is connected to the lower part from the crown 1b. In recent years, it has become common to individually manufacture these components and integrate them by welding.

Here, the runner crown 1b and the runner cone 1d will be described in detail.
The runner crown 1b is shaped like a truncated cone for fixing the main shaft on the inner side and the runner blade 1a on the outer side, and has sufficient inner and outer diameters relative to the size of the runner blade 1a. The runner blades 1a are joined along the outer surface, and water flows from an upper part having a large diameter to a lower part having a small diameter, and the flowing water is smoothly formed so as not to cause a flow loss.

  However, at the lowermost end, which is the end point of the runner crown 1b, the flow path is cut off and the shape of the flow path is abruptly changed, so that the loss of running water accompanying the rapid expansion of the flow path increases. In general, in order to prevent this loss, a member for smoothly extending the shape of the flow path called the runner cone 1d is attached to the lower end surface of the runner crown 1b, and the water discharged from the runner 1 is smoothly supplied to the upper suction pipe. It leads.

The runner cone 1d has a certain length, and extending the tip of the runner cone 1d to the center of the main shaft is an effective measure to reduce the loss of water flowing in the runner 1, but the runner cone 1b rotates together with the runner 1. Therefore, the shape and length are restricted. In particular, the longer the length, the higher the risk from the viewpoint of stability as a rotating body. For this reason, the runner cone 1b is generally a truncated cone provided with a flat portion at the bottom so as not to hinder the rotational movement (Patent Document 1), and has an appropriate length in view of performance and manufacturing cost. The correct shape is selected.
JP-A-4-72468

A phenomenon and problems occurring in the runner 1 of the conventional Francis type turbine described above will be described.
In general, in a Francis type turbine, a rope-like vortex called a whirl is generated at the center of the runner 1 at a partial load operation point and an overload operation point that are operation points away from a design point. The whirling swirls with the rotation of the runner 1, causing fluctuations in the pressure inside the suction pipe, and generating noise and vibration when this whirl extends downstream and collides with the suction pipe wall surface. It is often important to take measures to avoid this phenomenon.

The generation mechanism of this whirl will be described.
The shape of the runner blades is designed so that the water discharged from the runner 1 flows into the upper suction pipe as a so-called swirling flow having no rotational speed at the design point. On the other hand, at the non-design point, the balance between the rotational speed of the runner 1 and the speed of water in the runner 1 is lost, and the swirl speed component at the runner outlet becomes dominant, so that a whirl is generated. The size of this whirl depends on the magnitude of the turning speed component, and as the turning speed component increases as the distance from the design point increases, the swing becomes larger.

  In addition, since the amount of water flowing in the runner 1 is reduced relative to the design point at an operating point such as a partial load, the outside flows with respect to the inside of the runner 1 due to the centrifugal force action caused by the rotation of the runner 1. Due to the increased amount of water, this whirl has a thick and robust form. The lower end of the runner crown 1b, which is the blade outlet of the runner 1, serves as a base point for this whirl.

  Accordingly, the size of the runner cone 1d and the shape of the flow surface of the runner cone 1d influence the development of the whirl. As a special turbine, in the case of a tandem type turbine having another runner at the top of one runner 1, there is a penetrating main shaft between the runner and the runner. In this case, the whirl may not develop. It has been found that the shape of the central portion of the runner 1 avoids the development of the whirl.

  Although it is possible to suppress the development of the whirl by the shape of the runner cone 1d as described above, in the conventional runner structure, the runner cone 1d rotates at a high speed together with the runner 1, so that the shape cannot be freely designed. It has been difficult to take measures to suppress whirl amplification in the shape of the runner cone 1d itself.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a runner structure that can freely design the shape of a runner cone and can suppress the generation and development of a whirl.

  In order to achieve the above object, the runner structure of a hydraulic machine according to the present invention is a runner structure of a hydraulic machine comprising a main shaft, a runner blade, a runner crown, a runner barn, and a runner cone, wherein the runner cone is a central portion of the runner crown or the runner crown The main shaft is fastened by a connecting means that does not transmit rotational torque.

  According to the present invention, it is possible to freely design the shape of the runner cone by fastening the runner cone to the central portion or the main shaft of the runner crown by a connecting means that does not transmit rotational torque. It is possible to provide a runner structure that can suppress the generation of vibration noise and pressure pulsation due to the whirl.

An embodiment of a runner structure for a hydraulic machine according to the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is an overall configuration diagram of a runner structure according to a first embodiment of the present invention.

  The runner cone 1d according to the first embodiment has a conical shape, and the cross-sectional shape on the lower end side is a perfect circle. In the present embodiment, the runner crown 1b and the runner cone 1d are fastened together from the center of the runner crown 1b or the end of the main shaft 2 instead of integrally forming both the conventional welding and bolt fastening. To do.

  A main shaft 2 for transmitting the power generated by the runner 1 to the upper generator is connected to the center of the runner crown 1b. The lower portion of the center portion of the runner crown 1b or the lower end portion of the main shaft 2 and the runner cone 1d are fastened by, for example, connecting means including a connecting fitting 8 having a universal joint 7. This connecting means transmits axial force but does not transmit rotational force, and is like a general thrust bearing and requires a capacity to support the weight of the runner cone 1d.

  A sufficient gap 9 is provided between the lower end of the runner crown 1b and the upper end portion of the runner cone 1d so that they do not contact each other.

  With this configuration, when the runner 1 rotates due to the force of water, the rotation motion is not transmitted to the runner cone 1d. That is, since the runner cone 1d does not rotate with the runner 1, the runner cone 1d can be designed with a high degree of freedom, and the acceleration and amplification of the whirl caused by the rotation of the runner cone 1d can be suppressed. be able to.

  According to the first embodiment, the runner cone 1d does not synchronize with the rotational motion of the runner 1 and becomes a non-rotating body. Therefore, the shape of the runner cone 1d can be freely designed, and the conventional As described above, the whirl generated at the center of the runner 1 is not accelerated / amplified by the rotation of the runner cone 1d, and the generation of vibration noise and pressure pulsation due to the whirl can be suppressed.

[Second Embodiment]
Next, a runner structure according to a second embodiment of the present invention will be described with reference to FIGS.
In the runner cone 1d according to the second embodiment, the cross-sectional shape on the lower end side is not a perfect circle but a non-circular shape made of, for example, a polygon.

As a modification, as shown in FIG. 3, a non-circular runner cone 1d may be formed in which both side surfaces on the downstream side of the runner cone 1d shown in FIG. 1 or 2 are cut off and flat portions are formed on both sides.
The operation of the non-circular runner cone 1d will be described.

  The whirl is generated by the flow flowing out of the runner 1 and its behavior changes depending on the operating conditions, but the flow flowing out of the running runner 1 can be regarded as periodic and stable. . In other words, if the operating conditions do not change, the whirl also flows away downstream with a stable rotational motion with a certain period.

  Therefore, the whirling force of the whirl is suppressed by making the shape of the runner cone 1d non-circular and playing a role like a resistor.

  In the example of FIG. 2, the cross-sectional shape near the lower end of the runner cone is a hexagon, but a polygon other than a hexagon may be used in consideration of the manufacturing surface and workability.

  Further, as shown in FIG. 3, it is also effective to prevent the amplification of the whirl by increasing the effectiveness as a resistor by cutting off both sides of the runner cone 1d and providing a flat portion.

  According to the second embodiment, the runner cone 1d is not synchronized with the rotational motion of the runner 1, is a non-rotating body, and the shape of the runner cone 1d is non-circular, so that a whirl is generated. However, since this whirling force is not amplified, the generation of vibration noise and pressure pulsation due to the whirl can be further reduced.

[Third Embodiment]
Next, a runner structure according to a third embodiment of the present invention will be described with reference to FIGS.
The runner cone 1d according to the third embodiment is obtained by extending the lowermost position Lk of the runner cone 1d sufficiently downstream from the lower end position L of the runner band 1c. That is, in order to smoothly change the area of the flow path formed between the runner cone 1d and the upper suction pipe 6, the lowest position of the runner cone 1d is extended downstream from at least the lower end position of the runner band 1c. The outer shape of 1d is adjusted according to the shape of the upper suction pipe.

  Note that it is expected that the entire runner cone 1d becomes unstable by increasing the overall length of the runner cone 1d. In this case, however, as shown in FIG. By attaching the support member 10, it is possible to improve the stability without losing its functionality. The runner cone 1d support member 10 is mainly intended to prevent the runner cone 1d from swinging, and is preferably three or more.

  By adopting a structure in which the runner cone 1d is not rotated in this way, the runner cone 1d can be made long. On the other hand, it is the area change of the area surrounded by the runner cone 1d and the upper suction pipe 6 immediately after flowing out from the runner 1 that occupies a large ratio as a factor causing the loss in the runner 1. Although it is important that this area changes smoothly, in the conventional runner structure in which the runner cone 1d rotates, it is impossible to adjust the flow path area by the runner cone 1d, which causes an increase in loss.

  Therefore, in the present embodiment, the length Lk of the runner cone 1d is set to be at least larger than the height L value of the runner band 1c so that the area change can be adjusted by the shape of the runner cone 1d that is a non-rotating body. .

  In the example shown in FIG. 4, the shape of the runner cone 1d changes in two steps with the DR portion as a boundary. It is possible to design runner cones 1d of various shapes to achieve the change.

  According to the third embodiment, the bottommost position of the runner cone 1d is extended downstream from at least the lower end position of the runner band 1c, is stably supported by the support member 10, and the shape of the runner cone 1d is adjusted appropriately. As a result, the area change from the runner outlet to the suction pipe 6 can be made appropriate, so that the loss generated in the flow in the runner can be reduced.

  Further, since the runner cone 1d is completely accommodated in the whirl during operation, it is possible to sufficiently exhibit the effect of suppressing the whirling of the whirl, so that a highly efficient and stable water turbine operation can be realized.

[Fourth Embodiment]
A runner structure according to a fourth embodiment of the present invention will be described with reference to FIG.
In the fourth embodiment, the inside of the support member 10 that supports the runner cone 1d has a hollow structure and communicates with the outside of the upper suction pipe 6. Specifically, the hollow support member 10 is communicated with a pipe provided outside the upper suction pipe 6, and air from the outside is guided into the runner cone 1d through the hollow portion 11 inside the hollow support member 10, This air is injected from the gap 9 at the boundary between the runner crown 1b and the runner cone 1d into the flow channel downstream of the runner.

  Further, a valve 12 is provided in the pipe outside the upper suction pipe 6 and air is supplied to the runner cone 1d by opening and closing the valve 12 as necessary. The valve 12 is controlled to be opened and closed by an automatic control system linked to the driving conditions of the water turbine or a control system that is always open during the water turbine operation.

The operation of the fourth embodiment will be described.
A whirl is generated in the center of the runner, and this whirl is swung greatly or slightly depending on the driving conditions. Since the density of the injected air is small and the pressure at the center of the runner where the whirl is generated is lower than the surrounding pressure, the air injected near the center of the runner gathers in the center and gradually enters the interior of the whirl. It works to penetrate and increase the pressure in the whirl. As a result, the whirl that was shaken with a strong turning force changes to an umbrella-shaped stable form.

  By the way, when injecting air into the whirl, instead of injecting air from the inside of the runner cone 1d as in the present invention, when injecting air from the outside using an air supply pipe or the like protruding from the upper suction pipe 6, Since it is affected by the suction height of each power plant, the intake characteristics at the tip of the supply pipe are inferior, and therefore, equipment such as a compressor that is a device for creating high-pressure air may be required.

On the other hand, in the fourth embodiment, air can be injected in a timely manner at a point where a whirl is generated without requiring equipment such as a compressor.
According to the fourth embodiment, only the support member 10 of the runner cone 1d, which is a non-rotating body, has a hollow structure, and a large-scale air supply and injection device is not provided for the whirl generated in the water turbine operation region. However, since air can be efficiently injected by valve control, even if a whirl occurs, the generation of vibration noise and pressure pulsation can be suppressed, and a stable water turbine operation is possible.

[Fifth Embodiment]
A runner structure according to a fifth embodiment of the present invention will be described with reference to FIG.
In the fifth embodiment, the cross-sectional shape of the support member 10 of the third and fourth embodiments is a streamline type. Since the support member 10 is opposed to the flowing water flowing out from the runner 1 at a right angle, the thickness t ₁ of the upstream end portion and the thickness t ₁ of the downstream end portion of the current plate are reduced for the purpose of reducing fluid resistance. ₂ is made thinner than the maximum wall thickness tmax in the vicinity of the center so as not to be resistant to water flow. Of course, this shape can be applied even when the communication port 11 is provided inside.

  According to the fifth embodiment, since the fluid resistance can be minimized with respect to the fluid flowing out of the runner 1, it is possible to secure the fixing strength of the support member 10, and also according to the support member 10. Since significant loss increase can be prevented, stable water turbine operation and high efficiency operation are possible.

[Sixth Embodiment]
A runner structure according to a sixth embodiment of the present invention will be described with reference to FIG.
In the sixth embodiment, at least one rectifying plate 13 is provided radially on the outer wall surface of the runner cone 1d in the third embodiment. In FIG. 7, a plurality of rectifying plates 13 are radially attached to the outer wall surface of the runner cone 1d in parallel with the flowing water direction.

  During the operation of the water wheel, a whirl is generated around the runner cone 1d, and the whirl is shaken largely or slightly depending on the operating conditions. The rectifying plate 13 suppresses the whirling force. It also plays a role of rectifying the flow in an operating state where no whirl is generated.

  According to the sixth embodiment, by providing the rectifying plate 13 on the outer wall surface of the runner cone 1d, the whirling force of the whirl can be suppressed against the whirl generated in the water turbine operation region, and the development of the whirl Generation of vibration noise and pressure pulsation caused by Further, since there is an effect of rectifying the flow in the runner, stable water turbine operation and high efficiency operation are possible.

(A) is the runner structure figure based on the 1st Embodiment of this invention, (b) is the figure which looked at the runner cone from the lower end side. (A) is the runner structure figure concerning the 2nd Embodiment of this invention, (b) is the figure which looked at the runner cone from the lower end side. (A) is the modification of the runner structural drawing which concerns on the 2nd Embodiment of this invention, (b) is the figure which looked at the runner cone from the lower end side, (c) is the side view of a runner cone. The runner structure figure concerning the 3rd embodiment of the present invention. The runner structure figure which has the supporting member which concerns on the 3rd Embodiment of this invention. (A) is a runner structure figure concerning a 4th embodiment of the present invention, and (b) is a sectional view of a support member concerning a 5th embodiment of the present invention. The runner structure figure which has the supporting member which concerns on the 6th Embodiment of this invention. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... runner, 1a ... runner blade, 1b ... runner crown, 1c ... runner band, 1d ... runner cone, 2 ... main shaft, 3 ... casing, 4 ... steven, 5 ... guide vane, 6 ... upper suction pipe, 7 ... universal joint , 8 ... connecting metal fittings, 9 ... runner crown and runner cone gap, 10 ... support member, 11 ... communication port, 12 ... valve, DR ... runner cone intermediate part diameter, L ... runner band lower end position, Lk ... runner cone lower end position.

Claims (9)

  In the hydraulic machine runner structure comprising a main shaft, a runner blade, a runner crown, a runner burner, and a runner cone, the runner cone is fastened by a connecting means that does not transmit rotational torque to the central portion of the runner crown or the main shaft. Runner structure of hydraulic machine.   The runner structure for a hydraulic machine according to claim 1, wherein the downstream shape of the runner cone is conical or polygonal.   The runner structure for a hydraulic machine according to claim 2, wherein at least one flat portion is provided on the downstream side of the runner cone.   The runner structure for a hydraulic machine according to any one of claims 1 to 3, wherein a lowermost position of the runner cone is located downstream of a lower end position of the runner band.   5. The runner structure for a hydraulic machine according to claim 1, wherein the shape of the runner cone changes in a plurality of stages along the flow direction. 6.   The runner structure for a hydraulic machine according to any one of claims 1 to 5, wherein a plurality of support members for supporting the runner cone are arranged between the runner cone and the upper suction pipe.   The inside of the support member has a hollow structure so that air can be introduced into the runner cone from the outside of the upper blowing pipe, and the air can be injected into the flow channel under the runner from the gap between the runner cone and the runner crown. The runner structure of a hydraulic machine according to claim 6.   The runner structure for a hydraulic machine according to claim 6 or 7, wherein a cross-sectional shape of the support member is streamlined.   The runner structure for a hydraulic machine according to any one of claims 1 to 8, wherein one or a plurality of rectifying plates are provided radially on a part of an outer wall surface of the runner cone.

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