JP2009127572A - Suction tube for hydraulic machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suction tube of a hydraulic machine capable of reducing loss generated in the suction tube by inhibiting formation of horseshoe swirl which may be formed at a pier leading edge. <P>SOLUTION: The suction tube is constructed in such a manner that an expansion rate of the suction tube at a wake flow side of an upstream side end part 4 of the pier 3 is greater than an expansion rate of the suction tube at an upstream side of the upstream side end part 4 of the pier 3. In other words, when a section at the upstream side end part 4 of the pier 3 is represented by S0, channel section area of a section S2 at an upstream side of the section S0 is represented by AS2, channel section area of a section S1 at a position of which distance from the section S2 is R is represented by AS1, channel section area of a section S3 at a downstream side of the section S0 is represented by AS3, and channel section area of a section S4 at a position of which distance from the section S3 is R is represented by AS4, the suction tube is constructed to satisfy an inequality: (AS2-AS1)/R<(AS4-AS3)/R. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a suction pipe for a hydraulic machine having a peer (or partition plate).

  The suction pipe of the hydraulic machine is installed on the downstream side of the runner of the hydraulic machine, and guides a flow accompanied by swirling out of the runner to a drain outlet. At this time, the cross-sectional area inside the suction pipe gradually increases toward the downstream, and plays a role of reducing the kinetic energy to be discharged by decelerating the flow inside the suction pipe and increasing the pressure. .

  The suction pipe of the hydraulic machine may be buried in the ground or installed in the water depending on the use situation. Therefore, there is a possibility of deformation or damage due to the difference between the internal pressure and the external pressure. In order to avoid such a problem, a strength member called a peer is installed inside the suction pipe of the hydraulic machine.

  Since the pier has a thickness and a length that can withstand the force from the outside, a loss occurs due to collision, friction, secondary flow, and the like, and the performance of the entire hydraulic machine is degraded. Therefore, various methods have been proposed in order to suppress performance degradation due to the installation of a peer. Examples include Patent Document 1 and Patent Document 2. However, most of them attempt to mitigate the non-uniformity of the flow in the channel partitioned by the peers.

Japanese Patent Application Laid-Open No. 7-54754 JP-A-7-158550

  It is known that the flow flowing along the wall surface while gradually decelerating like the flow near the inner wall of the suction pipe is likely to cause boundary layer separation. Further, when a dull object such as a peer exists in the boundary layer, a characteristic vortex called a horseshoe vortex is generated in the vicinity of the junction between the object and the wall surface.

  Inside the suction pipe having the pier, a horseshoe vortex is formed at the junction between the leading edge of the peer and the suction pipe. This formation of a horseshoe vortex induces massive boundary layer separation around the front edge of the pier, causing significant loss. Therefore, suppressing the formation of horseshoe-shaped vortices and boundary layer separation at the leading edge of the peer is extremely important for loss reduction.

  The present invention has been made in view of such circumstances. A suction pipe for a hydraulic machine capable of suppressing the formation of a horseshoe vortex that can occur at the leading edge of the peer and reducing loss generated inside the suction pipe is provided. The purpose is to provide.

  In order to achieve the above object, the present invention provides a suction pipe in which the expansion ratio of the suction pipe on the downstream side from the upstream end of the peer is steeper than the expansion ratio on the upstream side of the upstream end of the peer. It is characterized by comprising.

  More specifically, the present invention relates to a suction of a hydraulic machine having a pier installed on the downstream side of a runner rotatably supported and on the upstream side of a water outlet and supported at at least one place on the inner wall. In the pipe, the section perpendicular to the central axis of the suction pipe, which is in contact with the upstream end of the pier and perpendicular to the central axis of the suction pipe, is S0 and is upstream of the cross section S0. The area of the flow path portion to be cut out is AS2, and exists between the cross section S2 and the rear end of the runner, and the distance of the cross section S2 measured along the central axis of the suction pipe is R. The area of the flow path part cut by the cross section S1 perpendicular to the central axis is AS1, and the flow path part cut by the cross section S3 perpendicular to the central axis of the suction pipe is downstream of the cross section S0. AS as area And a cross-section perpendicular to the central axis of the suction pipe through the position measured along the central axis of the suction pipe from the upstream end of the peer and approximately half the distance from the downstream end of the peer Is a section S4 that exists between the sections S3 and S5 and is perpendicular to the center axis of the suction pipe at a position where the distance from the section S3 measured along the center axis of the suction pipe is R. Assuming that the area of the flow path part cut out by AS4 is AS4, the suction pipe is configured so that (AS2-AS1) / R <(AS4-AS3) / R is satisfied.

  Further, according to the present invention, the area of the flow channel portion, which is located upstream of the upstream end portion of the pier and is cut by a cross section perpendicular to the central axis of the suction pipe, is substantially constant at any position. And the suction pipe is configured such that the cross-sectional area of the flow path gradually increases from the vicinity of the upstream end of the pier toward the downstream.

  According to the present invention, on the upstream side of the upstream end portion of the pier, the deceleration of the internal flow of the suction pipe is suppressed, so that the boundary layer on the inner wall of the suction pipe is unlikely to peel off. As a result, the thickness of the boundary layer on the upstream side of the upstream end of the pier becomes thinner, the formation of horseshoe vortices at the joint between the pier and the suction pipe is suppressed, and the loss in the suction pipe of the hydraulic machine is reduced. It is possible to improve hydraulic performance such as turbine efficiency and pump efficiency.

  Hereinafter, embodiments of a suction pipe of a hydraulic machine according to the present invention will be described with reference to the drawings.

[First Embodiment (Example 1)]
1 and 2 show a hydraulic plant (such as a runner and a suction pipe of a hydraulic machine) to which the present invention is applied (illustration of components (such as a generator) of a hydraulic machine other than the runner is omitted). Although FIG.1 and FIG.2 has shown the example applied to the horizontal axis Kaplan turbine (valve turbine or tubular turbine) as an example of a hydraulic machine, it is not limited to this. FIG. 1 is a top view of a runner, a suction pipe, a peer, and a drain outlet of a hydraulic machine according to the present invention as seen from a direction perpendicular to the flow, and FIG. 2 is a runner, a suction pipe of the hydraulic machine according to the present invention. , Pier, and drain outlet viewed from a direction perpendicular to the flow.

  As shown in FIG. 1 and FIG. 2, the suction pipe 2 of the hydraulic machine is installed on the downstream side of the runner 1 supported so as to be freely rotatable, and a flow 20 accompanied by swirling out of the runner 1 is discharged to the drain port 5. Leading to. At this time, the cross-sectional area inside the suction pipe gradually increases toward the downstream, and plays a role of reducing the kinetic energy to be discharged by decelerating the flow inside the suction pipe and increasing the pressure. . Further, as will be described in detail with reference to FIGS. 3 and 5, the suction pipe 2 is configured such that the enlargement ratio of the flow path cross-sectional area increases in the wake from the position of the upstream end 4 of the pier 3. . Inside the suction pipe 2 of the hydraulic machine, a pier that is a strength member is installed. The pier 3 is supported at at least one location on the inner wall of the suction pipe (in this embodiment, it is supported at two locations at the top and bottom).

  Next, this embodiment will be described in detail with reference to FIGS. In the present embodiment, the rate of increase of the channel cross-sectional area is different between the upstream side and the downstream side from the cross-section S0 in contact with the upstream end 4 of the peer, and the downstream side is rapidly expanding.

  On the upstream side of the cross-section S0, the flow-path cross-sectional areas AS1 and AS2 (the cross-sectional shapes are shown in FIG. In the drawings showing the channel cross sections, only the cross-sectional shape is shown in the same manner.), And the distance R from each other on the downstream side of the cross-section S0. The configuration of the suction pipe of the present embodiment is represented by using flow path cross-sectional areas AS3 and AS4 (the cross-sectional shapes of the cross section S3 and the cross section S4 are shown in FIG. 6) perpendicular to the central axis of the suction pipes that are separated from each other. (AS2-AS1) / R <(AS4-AS3) / R. At this time, the cross-section S3 and the cross-section S4 pass through the position measured along the central axis of the suction pipe 2 from the upstream end 4 of the pier, and the central axis of the suction pipe passes through approximately half the distance from the downstream end. Exists on the upstream side of the cross section S5 perpendicular to.

  FIG. 7 is a comparison of the cross-sectional area inside the suction pipe between this embodiment and the conventional configuration. Here, the horizontal axis is the position along the central axis of the suction pipe. Thus, the enlargement ratio of the channel cross-sectional area is different at the position of the upstream end of the peer, that is, the enlargement ratio on the downstream side of the upstream end of the peer is upstream of the upstream end of the peer. It can be confirmed that the ratio is larger than the enlargement ratio. However, in many cases, the pier 3 is made of concrete, and therefore the upstream end of the pier cannot be sharply pointed due to processing restrictions. For this reason, in this embodiment, the evaluation is made with respect to the portion excluding the vicinity of the upstream end portion of the peer (the range understood in relation to the processing constraints).

  FIG. 8 is an enlarged view of the vicinity of the joint between the upstream end 4 of the peer and the suction pipe 2 when the embodiment shown in FIG. 3 is viewed from the side. In the vicinity of the junction between the upstream end 4 of the pier and the suction pipe 2, a vortex structure called a horseshoe vortex 10 is generated. The horseshoe vortex 10 promotes separation of the boundary layer and causes a secondary flow with a strong backflow 11 in the boundary layer. In the case of the embodiment shown in FIG. 3, on the upstream side of the upstream end portion 4 of the pier, the deceleration of the internal flow of the suction pipe is suppressed, so that the boundary layer is hardly separated on the inner wall of the suction pipe. As a result, the thickness of the boundary layer on the upstream side of the upstream end portion 4 of the pier becomes thinner, and the formation of the horseshoe vortex 10 at the junction between the pier 3 and the suction pipe 2 is suppressed. Moreover, in the conventional form, peeling of the boundary layer is further promoted by the influence of the formed horseshoe vortex 10, but the embodiment of the present invention also has an effect of suppressing this. From the above, the secondary flow loss in the vicinity of the upstream end 4 of the peer is reduced.

  FIG. 9 shows a comparison of the total pressure loss inside the suction pipe using the general-purpose viscous turbulent flow analysis code in the conventional configuration and the embodiment of the present invention. The horizontal axis indicates the coordinate in the flow direction, and the vertical axis indicates the total pressure loss. From this, it can be seen that the increase in the loss in the vicinity of the upstream end 4 of the peer can be suppressed by configuring the suction pipe as in the embodiment of the present invention.

  FIG. 10 shows the ratio (AS2-AS1) / (AS4-AS3) of the channel cross-sectional area expansion amount upstream of the upstream end of the pier and the downstream channel cross-sectional area expansion amount on the horizontal axis. The area expansion ratio (AS2-AS1) / R and the ratio of (AS4-AS3) / R) is a graph in which the vertical axis represents the total pressure loss in the suction pipe. Thus, the smaller the (AS2-AS1) / (AS4-AS3), the smaller the loss. By making (AS2-AS1) / (AS4-AS3) smaller than 1, the loss can be greatly reduced. In addition, it can be confirmed that the loss is the smallest among (AS2-AS1) / (AS4-AS3) to 0.7 among the three kinds of conditions evaluated.

[Second Embodiment (Example 2)]
Another embodiment according to the present invention is shown in FIG. In the first embodiment of the present invention described above, the suction pipe continues to expand monotonically from the upstream end 4 of the pier to the drain 5. However, as the flow inside the suction pipe is enlarged, the flow velocity gradually decreases, and boundary layer separation and secondary flow are likely to occur.

  Therefore, in the present embodiment, as shown in FIG. 11, after suddenly expanding in the vicinity of the upstream end portion 4 of the peer, the expansion ratio is further suppressed at the downstream position S10. By comprising in this way, boundary layer peeling and backflow in the downstream from the upstream edge part 4 of a peer can be suppressed. In this case, the form described in the first embodiment must be provided in the range from the end portion on the downstream side of the runner to the S10 cross section. Alternatively, the condition of (AS2-AS1) / R <(AS4-AS3) / R when the S10 cross section is regarded as the S5 cross section must be satisfied. At this time, since the expansion ratio can be abruptly expanded in the range from the upstream end of the peer to the S10 cross section, the ratio of (AS2-AS1) / (AS4-AS3) can be reduced, and the loss Can be reduced.

  Alternatively, as shown in FIG. 12, a plurality of cross sections S11, S12, and S13 are taken downstream from the upstream end portion 4 of the peer, and the cross-sectional area is expanded most rapidly in the section from the cross section S0 to the cross section S11. It may be configured. In this case, in the range from the rear end of the runner to the S11 cross section, the form described in Example 1 must be used. Alternatively, the condition of (AS2-AS1) / R <(AS4-AS3) / R when the S11 cross section is regarded as the S5 cross section must be satisfied. At this time, since the expansion ratio can be abruptly expanded in the range from the upstream end of the peer to the S11 cross section, the ratio of (AS2-AS1) / (AS4-AS3) can be reduced, and the loss Can be reduced.

  Alternatively, as shown in FIG. 13, the suction pipe may be formed with a smooth free-form surface. In this case, the conditions described in Example 1 must be satisfied. Alternatively, there must be at least one combination of the sections S1, S2, S3, S4 perpendicular to the central axis of the suction pipe that satisfies the condition (AS2-AS1) / R <(AS4-AS3) / R. .

[Third Embodiment (Example 3)]
Another embodiment according to the present invention is shown in FIG. In this embodiment, the cross-sectional area on the upstream side from the position in contact with the upstream end 4 of the peer is formed to be substantially constant. Further, the suction pipe is configured so that the cross-sectional area of the flow path gradually increases from the vicinity of the upstream end of the pier toward the downstream. As described above, when the cross-sectional area of the suction pipe is substantially constant on the upstream side of the upstream end portion 4 of the peer, the flow velocity hardly decreases on the upstream side of the upstream end portion 4 of the peer. For this reason, the horseshoe vortex formed in the vicinity of the junction between the upstream end 4 of the pier and the suction pipe 2 is effectively suppressed, and the secondary flow loss at this position is effectively reduced. In addition, if the flow path cross-sectional area satisfies the condition of 0 ≦ (AS2−AS1) /R≦0.2, it is effective in suppressing the formation of horseshoe vortex.

  Further, when the flow passage cross-sectional area is configured to gradually increase from the vicinity of the upstream end portion of the pier toward the downstream, the enlargement ratio may be changed as in the second embodiment.

[Fourth Embodiment (Example 4)]
The present invention regulates the distribution of the channel cross-sectional area, and there is no particular restriction on the shape thereof. Therefore, as long as the distribution of the cross-sectional area is the same as that in any one of the first to third embodiments, the shape of each cross-section may be formed vertically or horizontally. In the present embodiment, when the vertical direction on the drawing of FIG. 15 is the vertical direction, the cross sections S0, S1, S2, S3, and S4 are formed in a vertically long shape as shown in FIGS. As can be seen from FIGS. 15 and 16, in this embodiment, on the upstream side of the upstream end portion 4 of the peer 3, only the direction seen from the top view of FIG. 4 on the upstream side of the pier 3 by increasing the expansion ratio of the channel cross-sectional area by expanding in both the direction seen from the top view of FIG. 15 and the direction seen from the side view of FIG. The suction pipe is configured to be large on the wake side of 4.

The top view which looked at the runner, the suction pipe, the peer, and the drain outlet of the hydraulic machine which concerns on this invention from the direction perpendicular | vertical to a flow. The side view which looked at the runner, the suction pipe, the peer, and the drain outlet of the hydraulic machine which concerns on this invention from the direction perpendicular | vertical to a flow. The top view which looked at the suction pipe, the peer, and the drain outlet from the direction perpendicular | vertical to a flow about 1st Embodiment of the hydraulic machine which concerns on this invention. Sectional drawing in S1, S2 of the suction pipe shown in FIG. Sectional drawing in S0 of the suction pipe shown in FIG. Sectional drawing in S3 and S4 of the suction pipe shown in FIG. The figure which compared the relationship between the cross-sectional area inside a suction pipe, and a flow direction coordinate about the conventional form and 1st Embodiment of this invention. The side view which expanded the upstream end part vicinity of the peer about 1st Embodiment of the hydraulic machine which concerns on this invention. The figure which calculated and compared the total pressure loss in a suction pipe using the viscous turbulent flow analysis code | cord | chord about the conventional form and the 1st Embodiment of this invention. The figure showing the loss in a suction pipe with respect to the ratio of the flow-path cross-sectional area increase amount in an upstream from the edge part of the upstream of a pier, and the flow-path cross-sectional area increase in a downstream. The figure showing an example at the time of making the cross section which relieves rapid expansion into one place about 2nd Embodiment of the hydraulic machine which concerns on this invention. The figure showing an example at the time of making 2 or more the cross section which relieves rapid expansion about 2nd Embodiment of the hydraulic machine which concerns on this invention. The figure showing an example at the time of forming 2nd Embodiment of the hydraulic machine which concerns on this invention using a free-form surface. The top view which looked at the suction pipe, the peer, and the drain outlet from the direction perpendicular | vertical to a flow about 3rd Embodiment of the hydraulic machine which concerns on this invention. The top view which looked at the suction pipe, the peer, and the drain outlet from the direction perpendicular | vertical to a flow about 4th Embodiment of the hydraulic machine which concerns on this invention. The side view which looked at the suction pipe, the peer, and the drain outlet from the direction perpendicular | vertical to a flow about 4th Embodiment of the hydraulic machine which concerns on this invention. Sectional drawing in S1, S2 of the suction pipe shown in FIG. Sectional drawing in S0 of the suction pipe | tube shown in FIG. Sectional drawing in S3 and S4 of the suction pipe shown in FIG.

Explanation of symbols

1 runner 2 suction pipe 3 pier 4 upstream end 5 of pier 5 drain port 10 horseshoe vortex 11 backflow 20 flow

Claims (6)

In the suction pipe of the hydraulic machine installed on the downstream side of the runner of the hydraulic machine and upstream of the drain,
Having a peer supported at at least one location on the inner wall of the suction pipe;
The suction pipe of a hydraulic machine, characterized in that the expansion ratio of the suction pipe on the downstream side from the upstream end of the peer is steeper than the expansion ratio of the suction pipe on the upstream side of the upstream end of the peer. . In a suction pipe of a hydraulic machine having a pier installed on the downstream side of a runner supported for rotation and upstream of a drain outlet and supported by at least one place on the inner wall,
S0 is a cross section perpendicular to the central axis of the suction pipe at the position of the upstream end of the peer,
AS2 is an area of a flow path portion cut by a cross section S2 perpendicular to the central axis of the suction pipe at a position upstream of the position of the cross section S0.
The position between the position of the cross section S2 and the rear end of the runner is a distance R from the cross section S2 measured along the central axis of the suction pipe, and is perpendicular to the central axis of the suction pipe. Let AS1 be the area of the channel portion cut by the cross section S1,
AS3 is an area of a flow path portion cut by a cross section S3 perpendicular to the central axis of the suction pipe at a position downstream of the position of the cross section S0,
The distance measured along the central axis of the suction pipe from the upstream end of the peer passes through a position approximately half the distance from the downstream end of the peer and is perpendicular to the central axis of the suction pipe. The cross section is S5,
And, at a position where the distance from the cross section S3 measured along the central axis of the suction pipe between the cross section S3 and the cross section S5 is R, the cross section S4 is perpendicular to the central axis of the suction pipe. If the area of the channel part to be cut is AS4,
A suction pipe for a hydraulic machine, wherein (AS2-AS1) / R <(AS4-AS3) / R is established. In the suction pipe of the hydraulic machine installed on the downstream side of the runner of the hydraulic machine and upstream of the drain,
Having a peer supported at at least one location on the inner wall of the suction pipe;
The suction pipe is configured such that the area of the flow path portion cut by a cross section perpendicular to the central axis of the suction pipe is substantially constant at any position upstream from the upstream end of the peer. ,
A suction pipe for a hydraulic machine, wherein the suction pipe is configured such that a cross-sectional area of a flow path increases from the vicinity of an upstream end portion of the pier toward a wake. In the suction pipe of the hydraulic machine installed on the downstream side of the runner of the hydraulic machine and upstream of the drain,
Having a peer supported at at least one location on the inner wall of the suction pipe;
S0 is a cross section perpendicular to the central axis of the suction pipe at the position of the upstream end of the peer,
AS2 is an area of a flow path portion cut by a cross section S2 perpendicular to the central axis of the suction pipe at a position upstream of the position of the cross section S0.
In addition, the distance between the position of the cross section S2 and the rear end portion of the runner is R from the cross section S2 measured along the central axis of the suction pipe, and is perpendicular to the central axis of the suction pipe. When the area of the flow path portion cut out by a simple cross section S1 is AS1,
0 ≦ (AS2-AS1) /R≦0.2
The suction pipe is configured so that
A suction pipe for a hydraulic machine, wherein the suction pipe is configured such that a cross-sectional area of a flow path increases from the vicinity of an upstream end portion of the pier toward a wake.   5. The expansion ratio according to claim 1, wherein the expansion ratio of the suction pipe downstream from the upstream end of the peer is increased in a plurality of stages so that the expansion ratio decreases toward the downstream side. A hydraulic machine suction pipe characterized by a change.   A hydraulic power plant having a hydraulic machine having a runner supported so as to freely rotate, a suction pipe according to any one of claims 1 to 4, and a drain port connected to the suction pipe.

Images