JP7185503B2 - Fluid machinery and method of refurbishing fluid machinery - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to a fluid machine, a seal member, and a repair method for the fluid machine.

2. Description of the Related Art Some fluid machinery used for hydraulic power generation and the like has a runner as a rotating member and upper and lower covers as stationary members that cover the runner. In such a fluid machine, a space called a back pressure chamber is formed between the runner and the upper cover, and a space called a side pressure chamber is formed between the runner and the lower cover.

The runner rotates under the pressure of the water stream at its runner blades to generate power for hydroelectric power generation. However, during such operation, there is a water flow that passes through the above-described back pressure chamber and side pressure chamber without passing through the runner.

Since the water flow that does not pass through the runner does not apply fluid force to the runner blades, the efficiency of the fluid machine decreases as the flow rate of the water flow that passes through the back pressure chamber and the side pressure chamber increases. The water flow flowing through the back pressure chamber and the side pressure chamber is generally called leakage flow, and the loss caused by the leakage flow is generally called leakage loss.

There are various techniques for suppressing leakage loss. For example, a minute gap is formed between the runner and the stationary member within the range of structurally permissible dimensions, and the minute gap prevents the flow of leakage flow. There are known a seal structure that suppresses this, and a seal structure that narrows the gap by forming rectangular or thread-shaped projections on the seal surface on the side of the stationary member.

A seal structure is also known in which circumferential grooves are formed in the wall portions of the rotating members or the wall portions of the stationary members facing each other. In this seal structure, the flow path area of the gap is expanded and reduced by the grooves, so that the leakage flow is decelerated and then immediately accelerated, and a sealing effect can be obtained by collision, friction with the wall surface, and the like.

Japanese Utility Model Laid-Open No. 54-53145 Japanese Patent No. 5835687

By the way, the leakage flow flowing through the gap between the rotating member and the stationary member has a large circumferential velocity component when passing through the gap due to friction with the rotating member. Although the seal structure in which circumferential grooves are formed in the wall portion of the rotating member or the wall portion of the stationary member described above can effectively decelerate the axial velocity component of leakage flow, There is room for improvement in terms of deceleration.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a fluid machine, a sealing member, and a fluid machine capable of improving the sealing effect against fluid passing between a rotating member and a stationary member and effectively suppressing leakage loss. The purpose is to provide a repair method for

A fluid machine according to one embodiment includes a rotating member that rotates due to fluid pressure, and a stationary member that covers the rotating member. At least one of the wall portion of the rotating member and the wall portion of the stationary member facing each other has a groove extending in the circumferential direction and a damming portion positioned to partially fill the groove. .

A fluid machine according to one embodiment includes a rotating member that rotates due to fluid pressure, and a stationary member that covers the rotating member. Between the wall portion of the rotating member and the wall portion of the stationary member facing each other, there is a first gap and a second gap spaced apart from the first gap in both the radial direction and the axial direction. , and a third gap positioned between the first gap and the second gap and coupled to both the first gap and the second gap so as to form a bent shape. there is At least one of the wall portion of the rotating member and the wall portion of the stationary member has a blocking portion positioned to partially fill the third gap.

A sealing member according to one embodiment includes a rotating member that rotates by fluid pressure and a stationary member that covers the rotating member, and the wall portion of the rotating member and the wall portion of the stationary member facing each other are included. is a seal member used in a fluid machine having a circumferentially extending groove. The seal member is arranged inside the groove and is provided so as to partially fill the groove.

A method for repairing a fluid machine according to one embodiment includes a rotating member that rotates by the pressure of a fluid and a stationary member that covers the rotating member. At least one of the parts is a modification method of a fluid machine having a groove extending in a circumferential direction. The refurbishment method includes a step of preparing a damming portion, and a step of providing the damming portion inside the groove so as to partially fill the groove.

ADVANTAGE OF THE INVENTION According to this invention, the sealing effect with respect to the fluid which passes between a rotating member and a stationary member can be improved, and leakage loss can be suppressed effectively.

1 is a meridional cross-sectional view of a Francis turbine as a fluid machine according to a first embodiment; FIG. 2 is an enlarged meridional cross-sectional view of a seal structure formed between a runner and a lower cover of the Francis turbine according to the first embodiment; FIG. FIG. 3 is a schematic view of a portion on the lower cover side that constitutes the seal structure in the first embodiment when viewed in the direction of arrow III in FIG. 2; (A) is a diagram for explaining a fluid machine according to a second embodiment, and is a view of a portion on the lower cover side that constitutes the seal structure when viewed in the same direction as the direction of arrow III in FIG. and (B) and (C) are diagrams showing modifications. FIG. 10 is a diagram for explaining a fluid machine according to a third embodiment, and is a schematic diagram of a portion on the lower cover side that constitutes the seal structure when viewed in the same direction as the direction of arrow III in FIG. 2 ; . FIG. 10 is a diagram for explaining a fluid machine according to a fourth embodiment, and is a schematic diagram of a portion on the lower cover side constituting the seal structure when viewed in the same direction as the direction of arrow III in FIG. 2; . FIG. 11 is a diagram for explaining a fluid machine according to a fifth embodiment, and is a schematic diagram of a portion on the lower cover side that constitutes the seal structure when viewed in the same direction as the direction of arrow III in FIG. 2 ; . FIG. 8 is a cross-sectional view along line VIII-VIII of FIG. 7; FIG. 10 is a diagram for explaining a fluid machine according to a sixth embodiment, and is a meridional cross-sectional view of the seal structure. FIG. 10 is a cross-sectional view along line XX of FIG. 9;

Each embodiment will be described in detail below with reference to the accompanying drawings.

<First embodiment>
FIG. 1 is a meridional cross-sectional view of part of a Francis turbine 1 as a fluid machine according to the first embodiment. Although the Francis type water turbine 1 will be described as an example of the fluid machine here, the fluid machine is not limited to the water turbine. In addition, in FIG. 1, for convenience of explanation, the hatching of the constituent members of the Francis type water turbine 1 is omitted.

In the Francis type water turbine 1 shown in FIG. 1, water flow from the casing 10 flows into the runner 2, which is a rotating member, through the stay vanes 11 and the guide vanes 12, and the runner 2 rotates due to the pressure of the water flow. It rotates around the axis C1.

In the following description, simply referring to the axial direction means the direction on the rotation axis C1 or the direction along the rotation axis C1. The term "circumferential direction" means the direction along the direction in which the runner 2 rotates about the rotation axis C1, and the term "radial direction" means the direction orthogonal to the rotation axis C1.

The runner 2 includes a plurality of runner blades 3 arranged so as to be arranged in a circumferential direction, a crown 4 that is an annular member that fixes the plurality of runner blades 3 from one side in the blade height direction, and a crown 4 that fixes the plurality of runner blades 3 from the other side. and a band 5, which is an annular member that

Reference numeral 6 in the drawing denotes a lower cover as a stationary member that covers the runner 2, particularly the band 5, from the outside in the radial direction. A side pressure chamber 7 that is a space is formed between the band 5 and the lower cover 6 . Although not shown, an upper cover as a stationary member is provided above the crown 4 to cover the crown 4 from above, and a back pressure chamber, which is a space, is formed between the upper cover and the crown 4 .

In this embodiment, a seal structure 20 is formed in a portion downstream of the side pressure chamber 7 in the direction of water flow, and the seal structure 20 forms a minute gap that narrows the space between the band 5 and the lower cover 6. This makes it difficult for leakage flow to pass through.

FIG. 2 is an enlarged meridional cross-sectional view of the seal structure 20. As shown in FIG. As shown in FIG. 2, the seal structure 20 according to the present embodiment includes a seal liner 21 attached to a downstream portion of the lower cover 6 in the direction of water flow and covering the band 5 from the outside in the radial direction; and the downstream portion of the band 5 . In the seal structure 20, the wall portion 21A of the seal liner 21 and the wall portion 5A of the band 5, which face each other in the radial direction, narrow the gap from the upstream side to form a minute gap. A minute gap between the wall portion 21A of the seal liner 21 and the wall portion 5A of the band 5 extends continuously in the circumferential direction to form an annular shape.

The wall portion 21A of the seal liner 21 has a groove 22 extending in the circumferential direction, and the groove 22 in this embodiment is formed in an annular shape extending over the entire circumference in the horizontal plane. However, groove 22 need not be annular and may be arcuate. Although three grooves 22 are formed in FIG. 2, the number of grooves 22 is not particularly limited. Furthermore, the cross-sectional shape of the groove 22 in the present embodiment is rectangular in the meridional cross-section, but the cross-sectional shape is not particularly limited, and may be, for example, trapezoidal or semicircular.

FIG. 3 shows a schematic view of the portion of the seal structure 20 on the side of the lower cover 6, specifically the seal liner 21, viewed in the direction of arrow III in FIG. As shown in FIGS. 2 and 3, the runner 2 according to the present embodiment is provided with a damming portion 23 that partially fills the groove 22 . Although one damming portion 23 is provided in each groove 22 in the present embodiment, a plurality of damming portions 23 may be provided in one groove 22 . Also, some of the plurality of grooves 22 may not be provided with the damming portion 23 .

The damming portion 23 functions as a sealing member for enhancing the sealing effect in cooperation with the groove 22 . The damming portion 23 exemplified in the present embodiment completely fills the space between the walls of the grooves 22 facing each other in the axial direction, but is arranged so as to provide a gap between the walls of the grooves 22 facing each other in the axial direction. may be provided. Moreover, although the shape of the damming portion 23 is rectangular when viewed in the radial direction, the shape is not particularly limited. The method of forming the damming portion 23 is not particularly limited, and it may be formed as an integral part of the seal liner 21, or may be formed as a separate part of the seal liner 21 and welded to the seal liner 21. may be attached.

Next, the operation of this embodiment will be described with reference to FIGS. 2 and 3. FIG.

During operation of the water turbine, when the water flow from the casing 10 flows into the runner 2, which is a rotating member, through the stay vanes 11 and the guide vanes 12, the runner blades 3 of the runner 2 rotate due to the pressure of the water flow. At this time, a leak flow, which is a part of the water flow, flows into the side pressure chamber 7 .

The leakage flow in the side pressure chamber 7 is suppressed from passing downstream by the minute gap between the wall portion 21A of the seal liner 21 and the wall portion 5A of the band 5 in the seal structure 20, and the groove 22 reduces the flow path area. Passage to the downstream side is further suppressed by repeating deceleration and acceleration due to the increase and decrease of . However, at this time, the leakage flow in the minute gap is affected by the rotation of the band 5 as indicated by the arrow α in FIG. Then, a situation may arise in which the circumferential velocity of the leakage flow cannot be sufficiently suppressed only by the grooves 22, and the leakage flow tries to flow out from the seal structure 20 while maintaining a high velocity.

At this time, in the present embodiment, the damming portion 23 positioned so as to partially fill the groove 22 is provided, so that the leakage flow having the above-described circumferential velocity flows through the groove 22 in the minute gap. When passing, it collides with the damming portion 23 and is dammed. As a result, the leakage flow is rapidly and largely decelerated, and passage of the leakage flow is suppressed as compared with the case where only the grooves 22 are provided.

As described above, according to the present embodiment, the sealing effect against the water flow (leakage flow) passing between the runner 2 and the seal liner 21 can be improved, and the leakage loss can be effectively suppressed.

In this embodiment, it is assumed that the damming portion 23 is provided when manufacturing a new fluid machine. It may be provided for the purpose of modification to the fluid machine. In this case, the damming portion 23 may be prepared, and the damming portion 23 may be provided inside the existing circumferential groove to partially fill the groove.

<Second Embodiment>
Next, a second embodiment will be described. The same reference numerals are assigned to the same components in the present embodiment as those in the first embodiment, and the description of the common parts may be omitted.

In this embodiment, as shown in FIG. 4A, a plurality of grooves 22 are provided in the seal liner 21 at intervals in the axial direction, and damming portions 23 are provided corresponding to each of the plurality of grooves 22. .

At least a portion of the plurality of damming portions 23 located downstream in the direction of the water flow indicated by the arrow F is greater than the damming portion 23 located upstream in the direction of rotation of the runner 2 . They are arranged so as to be located on the opposite side of R. Moreover, the damming portions 23 adjacent in the axial direction overlap each other in the axial direction.

In this embodiment as well, the leakage flow in the minute gap between the wall portion 21A of the seal liner 21 and the wall portion 5A of the band 5 has a circumferential component as indicated by the arrow α. The collision reduces the circumferential velocity. After this, the decelerated leakage flow exits the groove 22 and tries to flow in the axial direction.

Here, in the present embodiment, the damming portion 23 on the downstream side is located on the reverse side in the rotational direction R from the damming portion 23 on the upstream side. As a result, when the leakage flow decelerated by the damming portion 23 on the upstream side flows out of the groove 22 and tries to flow in the axial direction, the pressure inside the groove 22 on the damming portion 23 on the downstream side becomes higher than that in the groove 22 . Passage is constrained by the area in which it is located. As a result, the leakage flow is effectively suppressed, so the leakage loss can be effectively reduced.

Note that FIGS. 4B and 4C show modifications of the second embodiment. In the modification shown in FIG. 4B, the length of the damming portion 23 in the circumferential direction is longer toward the downstream side. As a result, at least a portion of the damming portion 23 positioned downstream in the water flow direction is positioned on the opposite side in the rotational direction R of the runner 2 than the damming portion 23 positioned upstream.

Further, in FIG. 4C, at least part of the damming portion 23 positioned downstream in the direction of water flow is positioned on the opposite side in the rotational direction R of the runner 2 than the damming portion 23 positioned upstream thereof. However, axially adjacent damming portions 23 are circumferentially separated and do not overlap each other in the axial direction.

<Third Embodiment>
Next, a third embodiment will be described. Of the components in this embodiment, those that are the same as those in the first and second embodiments are given the same reference numerals, and the description of the common parts may be omitted.

As shown in FIG. 5 , in this embodiment, a plurality of grooves 22 are provided in the seal liner 21 at intervals in the axial direction, and damming portions 23 are provided corresponding to each of the plurality of grooves 22 .

The end surface 23A of the damming portion 23 facing the opposite side of the rotation direction R of the runner 2 is inclined so as to extend in the opposite side of the rotation direction R as it extends from upstream to downstream in the direction of the water flow indicated by the arrow F. is doing.

In the present embodiment, after the circumferential velocity is decelerated by colliding with the damming portion 23, the leakage flow in the axial direction is further dammed and decelerated by the inclined end surface 23A. As a result, the leakage flow is effectively suppressed, so the leakage loss can be effectively reduced.

<Fourth Embodiment>
Next, a fourth embodiment will be described. Of the components in this embodiment, those that are the same as those in the first to third embodiments are denoted by the same reference numerals, and the description of the common parts may be omitted.

As shown in FIG. 6 , in this embodiment, a plurality of grooves 22 are provided in the seal liner 21 at intervals in the axial direction, and damming portions 23 are provided corresponding to each of the plurality of grooves 22 . The groove 22 is inclined at an angle β with respect to the horizontal direction so as to extend both in the circumferential direction and in the axial direction.

The angle β is set greater than 0°, and preferably set between 10° and 45° in consideration of the effect of leakage flow.

Also in this embodiment, the same effect as in the first embodiment can be obtained.

<Fifth Embodiment>
Next, a fifth embodiment will be described. Of the components in this embodiment, those that are the same as those in the first to fourth embodiments are denoted by the same reference numerals, and the description of the common parts may be omitted.

As shown in FIG. 7, in this embodiment, a plurality of grooves 22 are provided in the seal liner 21 at intervals in the axial direction, and damming portions 23 are provided corresponding to each of the plurality of grooves 22 .

As shown in FIG. 8, the damming portion 23 has a through hole 23B for passing a bolt 24, and is fixed inside the groove 22 by a bolt 24 as a fastening member. As shown in FIG. 8 , a bolt hole 25 is formed in the seal liner 21 and a bolt 24 is fastened to the bolt hole 25 . In the illustrated example, the bolt 24 is fastened so as not to protrude from the wall 21A of the seal liner 21, but the bolt 24 may protrude from the wall 21A. In the illustrated example, the bolt 24 does not pass through the seal liner 21, but the bolt 24 passes through the seal liner 21 and penetrates radially outward from the seal liner 21, and a nut is tightened on the exposed tip portion of the bolt 24. Thus, the damming portion 23 may be fixed.

When the damming portion 23 is formed in the groove 22, for example, the damming portion 23 can be formed by shaving at the same time as the groove 22 is cut. This leads to an increase in the number of grooving processes. This increases significantly as the number of locations where the damming portions 23 are provided increases. On the other hand, in the present embodiment, the damming portion 23 is fixed by the bolt 24 after the groove 22 has been formed, so that it is possible to shorten the process of forming the groove.

In addition, since the leakage flow in the side pressure chamber 7 may contain earth and sand, the damming portion 23 is worn out by the leakage flow containing the earth and sand, and the effect of damming the flow cannot be obtained over time, resulting in the effect of suppressing leakage loss. is considered to decrease. In such a case, in the present embodiment, the damming portion 23 can be replaced, so that the work load of the restoration work can be reduced.

<Sixth Embodiment>
Next, a sixth embodiment will be described. Of the components in this embodiment, those that are the same as those in the first to fifth embodiments are denoted by the same reference numerals, and the description of the common parts may be omitted.

As shown in FIG. 9, in this embodiment, a stepped seal structure is formed between the seal liner 21, which is a stationary member, and the band 5, which is a rotating member. The seal liner 21 has a stepped shape, and has a wall surface facing radially inward, a wall surface facing upstream of the water flow in the axial direction, and a wall surface facing radially inward in the direction of the water flow from upstream to downstream. The band 5 facing the seal liner 21 is also formed with a stepped shape.

between the seal liner 21 and the band 5 is a first gap 31 located upstream and forming a small radial gap; A second gap 32 that is positioned downstream of the first gap 31 and forms a minute gap in the radial direction, and a first gap 31 that is positioned between the first gap 31 and the second gap 32 . and the second gap 32 are formed to form a third gap 33 which is joined to form a bent shape, and each gap forms a sealing structure.

Each of the first gap 31, the second gap 32 and the third gap 33 has an annular shape. Also, the radial dimension of the third gap 33 is larger than those of the first gap 31 and the second gap 32 .

A damming portion 23 positioned to partially fill the third gap 33 is provided in the seal liner 21 . In the present embodiment, the damming portion 23 is provided on the wall surface of the seal liner 21 facing the upstream side of the water flow in the axial direction. may be provided.

The leakage flow in the first gap 31 functioning as a minute gap is affected by the rotation of the band 5 and becomes a flow having a circumferential velocity in the same direction as the rotation direction as indicated by the arrow α in FIG. , the flow entering the third gap 33 also has a circumferential velocity in the same direction as the direction of rotation. In the present embodiment, the damming portion 23 that partially fills the third gap 33 dams the leakage flow having a circumferential velocity, thereby rapidly decelerating the flow. Thereby, the sealing effect can be improved and the leakage loss can be effectively suppressed.

In this embodiment, the case where one damming portion 23 is provided to fill the third gap 33 is illustrated, but the number is not particularly limited.

Although each embodiment has been described above, each of the above embodiments is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and its equivalents.

For example, in the above-described first to fifth embodiments, the groove 22 and the damming portion 23 are provided in the seal liner 21, which is a stationary member, but the groove 22 may be provided on the band 5 side. . Also, the groove 22 and the damming portion 23 may be provided on both the rotating member and the stationary member.

DESCRIPTION OF SYMBOLS 1... Francis type water turbine, 2... Runner, 3... Runner blade, 4... Crown, 5... Band, 5A... Wall part, 6... Lower cover, 7... Side pressure chamber, 10... Casing, 11... Stay vane, 12... Guide vane , 20 Seal structure 21 Seal liner 21A Wall portion 22 Groove 23 Damping portion 23A End face 23B Through hole 24 Bolt 25 Bolt hole 31 First gap , 32... second gap, 33... third gap, C1... rotation axis

Claims (4)

a rotating member that rotates about a rotation axis by the pressure of a water stream and includes a plurality of runner blades and a band that fixes the plurality of runner blades; and a stationary member that covers the rotating member;
At least one of the wall portion of the band of the rotating member and the wall portion of the stationary member facing each other in a radial direction perpendicular to the axis of rotation has a plurality of grooves extending in the circumferential direction, and a portion of the groove. a damming portion positioned so as to be substantially buried;
The plurality of grooves are spaced apart in the axial direction,
The damming portion is provided corresponding to each of the plurality of grooves,
Of the damming portions provided in the grooves that are adjacent in the axial direction, some of the damming portions positioned downstream in the direction of flow of the water flow are positioned more upstream than those positioned upstream in the direction of rotation of the rotating member. The fluid machine, wherein the damming portions located on opposite sides and adjacent in the axial direction overlap each other in the axial direction. 2. The fluid machine according to claim 1, wherein said groove extends in said circumferential direction and is inclined so as to extend in said axial direction. 3. The fluid machine according to claim 1, wherein said damming portion is fixed inside said groove by a fastening member. A rotary member that rotates about a rotation axis by the pressure of a water stream and includes a plurality of runner blades and a band that fixes the plurality of runner blades; and a stationary member that covers the rotation member, and is perpendicular to the rotation axis At least one of the wall portion of the band of the rotating member and the wall portion of the stationary member, which are diametrically opposed to each other, has a plurality of grooves extending in the circumferential direction, and the plurality of grooves are configured to extend in the axial direction. A method for refurbishing a fluid machine that is spaced in a direction , comprising:
preparing a dam;
providing the damming portion inside each of the plurality of grooves so as to partially fill the grooves;
Of the damming portions provided in the grooves that are adjacent in the axial direction, some of the damming portions positioned downstream in the direction of flow of the water flow are positioned more upstream than those positioned upstream in the direction of rotation of the rotating member. A method for repairing a fluid machine, wherein the damming portions are provided so that the damming portions located on opposite sides and adjacent in the axial direction overlap each other in the axial direction.

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