JP6570947B2 - Hydraulic machine suction pipe device - Google Patents

Description

  Embodiments of the present invention relate to a suction pipe device of a hydraulic machine.

  As shown in FIG. 7, in a general Francis turbine 40, during power generation operation, the water flow that flows in from the upper pond (not shown) through the hydraulic iron pipe passes through the casing 41 and the stay vane 42, and the flow rate is adjusted. It flows to the runner 44 through the guide vane 43 to be performed. The pressure energy of the water flow is converted into the rotational energy of the runner 44, and the rotational driving force of the runner 44 is transmitted to the generator 47 coupled through the main shaft 46 to generate power. The water flow that has passed through the runner 44 passes through the suction pipe 50 and is discharged to a water discharge channel (not shown). During such power generation operation, the flow rate of water flowing into the runner 44 is adjusted by changing the opening of the guide vane 43 to change the power generation amount.

  Such a Francis turbine 40 is designed so that the hydraulic loss is minimized in an operation state (design point) assuming a flow rate and a drop with a high operation frequency. For this reason, at the design point, the water flow flowing from the casing 41 through the stay vane 42 and the guide vane 43 into the runner 44 is an ideal flow with little separation and secondary flow.

  As shown in FIG. 7, the suction pipe 50 includes an upper draft 51 provided on the runner 44 side and an enlarged pipe 53 connected to the upper draft 51 via an elbow 52. The water flow that has passed through the runner 44 flows downstream in the suction pipe 50 along the main flow direction indicated by the thick arrow in FIG.

US Pat. No. 6,729,843

  However, the elbow 52 of the suction pipe 50 is formed to bend the water flow greatly. For this reason, an inertial force acts on the water flow in the suction pipe 50, and the water flow in the suction pipe 50 can be a flow biased toward the outer peripheral wall portion 52 b of the elbow 52. In this case, as shown in FIG. 8, a low speed region 55 in which the speed of the water flow decreases can be formed on the inner peripheral wall portion 52 a side of the elbow 52, and in the direction perpendicular to the main flow direction inside the elbow 52. A secondary flow 54 may be generated that flows along a flow path wall that defines a flow path within the elbow 52. For this reason, this low speed area | region 55 can detach | leave from the inner peripheral wall part 52a, and a peeling flow can be formed. In this way, a separation region 56 where a separation flow exists may be formed on the inner peripheral wall portion 52a side of the elbow 52 and the upper wall portion 53a side of the expansion tube 53. As a result, large hydraulic loss and hydraulic vibration may occur.

  The present invention has been made in consideration of such points, and at the design point, a suction pipe device for a hydraulic machine that can suppress the occurrence of hydraulic loss and hydraulic vibration due to the separation flow in the suction pipe. The purpose is to provide.

  The suction pipe device of the hydraulic machine according to the embodiment is for flowing a water flow that has passed through a runner that is rotationally driven by the flowing water flow. The suction pipe device of this hydraulic machine connects the upper pipe arranged on the runner side, the enlarged pipe arranged on the side opposite to the runner side, the upper pipe and the enlarged pipe, and has a flow path for water flow. A bent pipe that is bent, and includes a bent pipe having an inner peripheral wall portion and an outer peripheral wall portion. A protruding wall that protrudes toward the outer peripheral wall portion is provided at the center in the width direction of the inner peripheral wall portion of the bent pipe.

  In addition, the suction pipe device of the hydraulic machine according to the embodiment is for flowing a water flow that has passed through a runner that is rotationally driven by the flowing water flow. The suction pipe device of this hydraulic machine connects the upper pipe arranged on the runner side, the enlarged pipe arranged on the side opposite to the runner side, the upper pipe and the enlarged pipe, and has a flow path for water flow. A bent pipe that is bent, and includes a bent pipe having an inner peripheral wall portion and an outer peripheral wall portion. Further, the suction pipe device of the hydraulic machine is provided at a central portion in the width direction of the inner peripheral wall portion of the bent pipe, and the water flow is divided into a hollow elastic body having an internal space partitioned from the internal space of the hollow elastic body. A fluid supply / discharge portion for supplying and discharging fluid. When a predetermined amount of fluid is supplied to the internal space, the hollow elastic body forms a protruding wall that protrudes toward the outer peripheral wall portion.

  According to the present invention, it is possible to suppress the occurrence of hydraulic loss and hydraulic vibration due to the separation flow in the suction pipe at the design point.

FIG. 1 is a schematic cross-sectional view showing the overall configuration of the Francis turbine according to the first embodiment. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a diagram showing hydraulic loss of the suction pipe of FIG. FIG. 4A is a view corresponding to the cross section taken along the line AA of FIG. 1 during low flow rate operation in the suction pipe according to the second embodiment. FIG. 4B is a view corresponding to the cross section taken along the line AA of FIG. 1 at the design point in the suction pipe according to the second embodiment. FIG. 5 is a schematic cross-sectional view for explaining the flow in the suction pipe of FIG. 2 during the low flow rate operation. FIG. 6A is a view corresponding to a cross section taken along line AA of FIG. 1 during low flow rate operation in the suction pipe according to the third embodiment. FIG. 6B is a view corresponding to the cross section taken along the line AA of FIG. 1 at the design point in the suction pipe according to the third embodiment. FIG. 7 is a schematic cross-sectional view showing the overall configuration of a general Francis turbine. 8 is a cross-sectional view taken along the line BB in FIG.

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

(First embodiment)
A suction pipe device for a hydraulic machine according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

  Here, a Francis turbine equipped with a suction pipe device will be described as an example of a hydraulic machine with reference to FIG. FIG. 1 is a schematic cross-sectional view showing the overall configuration of a Francis turbine.

  As shown in FIG. 1, the Francis turbine 1 includes a spiral casing 2 into which water flows from a top pond through a hydraulic iron pipe (none of which is shown), a plurality of stay vanes 3, and a plurality of guides during power generation operation. A vane 4 and a runner 5 are provided. Of these, the stay vane 3 is for guiding the water flow that has flowed into the casing 2 to the guide vane 4 and the runner 5. The stay vane 3 is arranged at a predetermined interval in the circumferential direction, and a flow path through which the water flow flows between the stay vanes 3. Is formed. The guide vanes 4 are used to guide the inflowing water flow to the runner 5, are arranged at a predetermined interval in the circumferential direction, and a flow path through which the water flow flows is formed between the guide vanes 4. The guide vane 4 is configured to be rotatable, and the flow rate of water flowing into the runner 5 can be adjusted by rotating the guide vane 4 to change the opening degree. In this way, the power generation amount of the generator 7 described later can be adjusted.

  The runner 5 is configured to be rotatable about the rotation axis X with respect to the casing 2 and is rotationally driven by a water flow flowing from the casing 2 during a power generation operation. That is, the runner 5 is for converting pressure energy of water flowing into the runner 5 into rotational energy. The runner 5 in the present embodiment is configured to rotate clockwise (clockwise) when viewed from above.

  A generator 7 is coupled to the runner 5 via a main shaft 6. The generator 7 is configured to generate power by transmitting the rotational energy of the runner 5 during power generation operation.

  On the downstream side of the runner 5, a suction pipe 8 that constitutes a suction pipe device 8 </ b> A that allows the water flow that has passed through the runner 5 to flow into the water discharge path 9 is provided. When the suction pipe 8 is connected to a lower pond (not shown) and the generator 7 also has a function as an electric motor, the generator 7 is runner by being supplied with electric power. You may be comprised so that 5 may be rotationally driven. In this case, the water in the lower pond can be sucked through the suction pipe 8 and discharged to the upper pond, and the Francis turbine 1 can be pumped.

  Next, the above-described suction pipe device 8A will be described in more detail with reference to FIGS. Here, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, that is, a cross-sectional view showing an elbow 12 described later in a cross section orthogonal to the main flow direction of the water flow, and FIG. 3 shows the suction pipe 8 of FIG. It is a figure which shows a hydraulic loss.

  As shown in FIG. 1, the suction pipe device 8 </ b> A includes a suction pipe 8. The suction pipe 8 includes an upper draft 10 (upper pipe) arranged on the runner 5 side, an enlarged pipe 11 arranged on the water discharge section 9 side (opposite side of the runner 5), and an upper draft 10 And an elbow 12 (bent pipe) that connects the expansion pipe 11 and bends the flow path of the water flow.

  The upper draft 10 is formed so that the main flow direction of the water flow flowing through the upper draft 10 (direction of the water flow when viewed globally, see the bold arrow in FIG. 1) is substantially vertical. The main flow direction of the water flow flowing through the expansion pipe 11 is formed substantially horizontally (so as to extend horizontally or to extend at a desired swing angle with respect to the horizontal). The elbow 12 is formed so as to bend the main flow direction of the water flow flowing through the elbow 12 in order to connect the upper draft 10 and the expansion pipe 11.

  The expansion tube 11 extends so that the cross-sectional area of the flow channel increases toward the downstream side. The expansion pipe 11 attempts to recover the pressure of the water flow by decelerating the flow velocity of the water flow.

  As shown in FIG. 1, the elbow 12 in the present embodiment has an inner peripheral wall portion 12a provided on the inner peripheral side with respect to the main flow direction to be bent, and an outer peripheral wall portion 12b provided on the outer peripheral side. doing. As shown in FIG. 2, the inner peripheral wall portion 12a and the outer peripheral wall portion 12b are connected by side walls 12c and 12d, and the elbow 12 forms a closed shape in a cross section orthogonal to the main flow direction of the water flow. ing.

  A protruding wall 13 that protrudes toward the outer peripheral wall portion 12 b is provided at the center in the width direction of the inner peripheral wall portion 12 a of the elbow 12. The protruding wall 13 is formed in a V shape so as to be convex toward the outer peripheral wall portion 12b when viewed in the cross section shown in FIG. 2, and on both sides in the width direction of the protruding wall 13, A channel wall that defines a channel in the elbow 12 is formed so as to be recessed toward the inner peripheral side (upper side in FIG. 2). The protruding wall 13 preferably extends from the elbow 12 into the expansion tube 11 along the main flow direction. Here, the width direction is a direction orthogonal to the main flow direction of the water flow, and means a horizontal direction (horizontal direction) when viewed in the cross section shown in FIG.

As shown in FIG. 2, when the elbow 12 has a protruding dimension of the protruding wall 13 as h and a dimension from the inner peripheral wall part 12a to the outer peripheral wall part 12b as H,
0 <h / H <0.3
It is preferable that More specifically, the dimension h indicates the distance between the portion of the wall surface of the inner peripheral wall portion 12a located on the innermost peripheral side (the upper side in FIG. 2) and the lower end of the protruding wall 13. Moreover, the dimension H has shown the distance of the part located in the innermost peripheral side among the wall surfaces of the inner peripheral wall part 12a, and the wall surface of the outer peripheral wall part 12b.

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

  When the power generation operation is performed in the Francis turbine 1 according to the present embodiment, as shown in FIG. 1, water flows into the casing 2 from the upper pond (not shown) through the hydraulic iron pipe. The water flowing into the casing 2 flows into the runner 5 from the casing 2 through the stay vanes 3 and the guide vanes 4. The runner 5 is rotationally driven by the water flowing into the runner 5. As a result, the generator 7 coupled to the runner 5 is driven to generate power. The water flowing into the runner 5 is discharged from the runner 5 through the suction pipe 8 to a lower pond (not shown).

  The water flow at the outlet of the runner 5 can change greatly depending on the difference in operating point such as a head or output. For this reason, the water that has passed through the runner 5 and has flowed into the suction pipe 8 passes through the elbow 12 in various flows. By the way, the elbow 12 has a bent shape in order to bend the flow path of the water flow. As a result, an inertial force acts on the water flow in the elbow 12, and the water flow in the elbow 12 is biased toward the outer peripheral wall portion 12 b of the elbow 12 at the design point. For this reason, while the low speed area | region 15 in which the speed of a water flow falls can be formed in the inner peripheral wall part 12a side of the elbow 12, inside the elbow 12 in the direction orthogonal to the mainstream direction of a water flow inside the elbow 12. A secondary flow 14 along the flow path wall can be generated.

  The generated secondary flow 14 flows from the outer peripheral wall portion 12b side to the inner peripheral wall portion 12a side along the outer peripheral wall portion 12b and the side walls 12c and 12d, as shown in FIG. And the secondary flow 14 flows to the width direction center side along the inner peripheral wall part 12a. At this time, the secondary flow 14 flows along the protruding wall 13 provided in the inner peripheral wall portion 12a. That is, the secondary flow 14 is inclined and flows toward the outer peripheral wall portion 12b. As a result, the secondary flow 14 flows toward the low velocity region 15 and can supply water to the low velocity region 14. For this reason, it can suppress that the low speed area | region 15 detach | leaves from the protrusion wall 13, and the flow biased to the outer peripheral wall part 12b side can be eased.

  The water flow that has passed through the elbow 12 flows into the expansion pipe 11, and after the pressure is recovered by reducing the flow velocity of the water flow, the water flow is discharged into the water discharge channel 9. Even when flowing through the expansion tube 11, similarly to the flow in the elbow 12 described above, the low-speed region that can be formed in the expansion tube 11 is prevented from detaching from the protruding wall 13 extending in the expansion tube 11. It is possible to alleviate the uneven flow.

  Further, the protruding wall 13 according to the present embodiment satisfies 0 <h / H <0.3 as described above. Here, the hydraulic loss of the suction pipe 8 is shown in FIG. The horizontal axis in FIG. 3 indicates h / H, and the vertical axis indicates hydraulic loss. If h is increased, the change in momentum of the flow in the elbow 12 can be increased, and the average flow velocity in the cross section perpendicular to the main flow direction can be increased. Therefore, the hydraulic loss is lower than the case where the protruding wall 13 is not provided. Can also be larger. However, as described above, by setting h / H to less than 0.3, it is possible to suppress an increase in hydraulic loss due to an increase in momentum change or an increase in average flow velocity.

  Thus, according to this Embodiment, the protrusion wall 13 which protrudes toward the outer peripheral wall part 12b is provided in the width direction center part of the inner peripheral wall part 12a of the elbow 12. As shown in FIG. Thus, the secondary flow 14 flowing along the inner peripheral wall portion 12a of the elbow 12 in a direction orthogonal to the main flow direction of the water flow can be inclined along the protruding wall 13 toward the outer peripheral wall portion 12b. For this reason, it can suppress that the low-speed area | region 15 which can be formed in the inner peripheral wall part 12a side of the elbow 12 can detach | leave from the protrusion wall 13, and the bias | inclination of the flow which generate | occur | produces in the elbow 12 can be eased. As a result, generation of a separation region in the elbow 12 can be suppressed, and generation of hydraulic loss and hydraulic vibration due to the separation flow in the suction pipe 8 can be suppressed at the design point.

  Further, according to the present embodiment, in the cross section orthogonal to the main flow direction of the water flow, the relationship between the protruding dimension h of the protruding wall 13 and the distance H between the inner peripheral wall portion 12a and the outer peripheral wall portion 12b is 0 <h. /H<0.3 is satisfied. This can effectively reduce hydraulic loss.

(Second Embodiment)
Next, a suction pipe device for a hydraulic machine according to a second embodiment of the present invention will be described with reference to FIGS. 4A to 5.

  In the second embodiment shown in FIG. 4A to FIG. 5, the hollow elastic body is provided on both sides in the width direction of the protruding wall and has a partitioned internal space, and the internal space of the hollow elastic body. The main difference is that it is further provided with a fluid supply / discharge section for supplying and discharging fluid, and other configurations are substantially the same as those of the first embodiment shown in FIGS. 4A to 5, the same parts as those in the first embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 4A and 4B, the suction pipe device 8A according to the present embodiment is provided on both sides of the protruding wall 13 in the width direction, and has a hollow elastic body 17 having an internal space 16 partitioned from a water flow, A fluid supply / discharge portion 20 that supplies and discharges fluid to and from the internal space 16 of the elastic body 17. Among these, as the material of the hollow elastic body 17, strong rubber such as hard rubber can be used.

  The hollow elastic body 17 can be expanded by supplying a fluid described later to the internal space 16. As shown in FIG. 4A, the expanded hollow elastic body 17 expands to the vicinity of the lower end of the protruding wall 13. Accordingly, in the cross section orthogonal to the main flow direction, the flow path wall on the inner peripheral wall portion 12a side can be formed in a substantially linear shape extending in the width direction by the hollow elastic body 17 and the protruding wall 13. . In this case, the channel wall in the elbow 12 in the cross section has a substantially rectangular shape as a whole.

  On the other hand, the hollow elastic body 17 can be contracted by discharging a fluid described later from the internal space 16. As shown in FIG. 4B, the contracted hollow elastic body 17 has a shape along the inner peripheral wall portion 12a. As a result, on both sides in the width direction of the protruding wall 13, the flow path wall on the inner peripheral wall portion 12 a side is recessed toward the inner peripheral side (upper side in FIG. 4B), and in the elbow 12 in a cross section orthogonal to the main flow direction. The flow path wall can be roughly similar to the shape shown in FIG. 2 in the first embodiment.

  Fluid supply / discharge of the fluid to / from the internal space 16 of the hollow elastic body 17 is performed by the fluid supply / discharge unit 20. The fluid supply / discharge unit 20 includes a fluid storage unit 21 that stores fluid supplied into the internal space 16, a pump 22 that supplies fluid to the internal space 16, and a pipe 23 that connects the fluid storage unit 20 and the internal space 16. And have. The pipe 23 is provided with a pump 22, and the pump 22 supplies the fluid stored in the fluid storage unit 21 to the internal space 16. The fluid may be a gas such as air or a liquid such as water as long as the hollow elastic body 17 can be expanded.

  When supplying the fluid, the pump 22 is driven, and the fluid stored in the fluid storage unit 21 is supplied to the internal space 16 of the hollow elastic body 17 through the pipe 23 and filled. In this case, the fluid is supplied to the internal space 16 to such an extent that the pressure of the fluid in the internal space 16 is higher than the pressure of the water flow in the elbow 12.

  On the other hand, when the fluid is discharged, the pump 22 is stopped, and the fluid filled in the internal space 16 is discharged and returned to the fluid storage unit 21 via the pipe 23. In this case, the fluid is discharged from the internal space 16 to the extent that the pressure of the fluid in the internal space 16 is lower than the pressure of the water flow in the elbow 12. When the fluid is discharged, the fluid filled in the internal space 16 may be discharged outside the system (not shown).

  During power generation operation at the design point, as shown in FIG. 4B, the fluid is discharged from the internal space 16, and the pressure of the fluid in the internal space 16 becomes low. As a result, the hollow elastic body 17 contracts under the pressure of the water flow. At this time, the flow path wall in the elbow 12 can be roughly shaped similar to the shape shown in FIG. 2 in the first embodiment described above.

  On the other hand, at the time of low flow rate operation, as shown in FIG. As a result, the pressure of the fluid in the internal space 16 increases, and the hollow elastic body 17 expands.

  Here, during the low flow operation, as shown in FIG. 5, the water flow in the elbow 12 may swirl along the rotation direction of the runner 5, and the swirling flow 18 may be generated. At this time, a vortex 19 may be generated on the downstream side (left side shown in FIG. 5) of the protruding wall 13 when viewed in the flow direction of the swirl flow 18. In this case, hydraulic loss may occur due to the generated vortex 19.

  In contrast, in the present embodiment, during the low flow rate operation, the hollow elastic body 17 is expanded as described above. As a result, as shown in FIG. 4A, the hollow elastic body 17 and the protruding wall 13 can form the flow path wall on the inner peripheral side wall 12a side in a substantially linear shape extending in the width direction. . For this reason, generation | occurrence | production of the vortex 19 as shown in FIG. 5 can be suppressed. The hollow elastic body 17 is preferably provided along the protruding wall 13 so as to extend in the mainstream direction. Thereby, generation | occurrence | production of the vortex 19 at the time of low flow operation can be suppressed further.

  In addition, even at the time of high flow operation, it is possible to suppress the generation of vortices as in the case of low flow operation. That is, during high flow operation, the water flow in the elbow 12 generates a swirl flow that swirls in a direction opposite to the swirl flow 18 (see FIG. 5) during low flow operation, and when viewed in the flow direction of the swirl flow. A vortex may occur on the downstream side of the protruding wall 13. However, if the suction pipe device 8A according to the present embodiment is used, the hollow elastic body 17 can be expanded to suppress the generation of vortices.

  Thus, according to the present embodiment, the hollow elastic body 17 can be expanded by supplying the fluid to the internal space 16. As a result, the flow path wall on the inner peripheral wall portion 12a side can be formed in a substantially linear shape extending in the width direction by the hollow elastic body 17 and the protruding wall 13. For this reason, it is possible to suppress the occurrence of the vortex 19 on the downstream side in the flow direction of the swirling flow 18 with respect to the protruding wall 13 during the low flow rate operation or the high flow rate operation, thereby suppressing hydraulic loss.

  Further, according to the present embodiment, the hollow elastic body 17 can be contracted by discharging the fluid from the internal space 16. Thereby, in the cross section orthogonal to the main flow direction, the flow path wall in the elbow 12 can be made to have a shape substantially similar to the shape shown in FIG. 2 in the first embodiment. For this reason, generation | occurrence | production of the hydraulic loss resulting from the peeling flow in the suction pipe 8 and a hydraulic pressure vibration can be suppressed in a design point.

  Furthermore, according to the present embodiment, the fluid supplied to the internal space 16 of the hollow elastic body 17 is stored in the fluid storage unit 21. As a result, a fluid required for expanding the hollow elastic body 17 can be secured in advance, and the hollow elastic body 17 can be smoothly expanded.

(Third embodiment)
Next, a suction pipe device for a hydraulic machine according to a third embodiment of the present invention will be described with reference to FIGS. 6A and 6B.

  In the third embodiment shown in FIGS. 6A and 6B, the hollow elastic body is provided at the center in the width direction of the inner peripheral wall portion of the bent tube, and when a predetermined amount of fluid is supplied to the internal space, the hollow elastic body The main difference is that the body forms a protruding wall that protrudes toward the outer peripheral wall, and other configurations are substantially the same as those of the second embodiment shown in FIGS. 4A to 5. 6A and 6B, the same parts as those of the second embodiment shown in FIGS. 4A to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 6A and 6B, the hollow elastic body 17 of the suction pipe device 8A according to the present embodiment is provided at the center in the width direction of the inner peripheral wall portion 12a of the elbow 12. When a predetermined amount of fluid is supplied to the internal space 16, the hollow elastic body 17 forms a protruding wall 24 that protrudes toward the outer peripheral wall portion 12b. That is, the protruding wall 13 is not provided on the inner peripheral wall portion 12a according to the present embodiment. For this reason, in the cross section orthogonal to the mainstream direction, the inner peripheral wall portion 12a is formed in a substantially linear shape. And the protruding wall 24 formed when the hollow elastic body 17 expand | swells has a function similar to the protruding wall 13 shown to FIG. 4A etc. in above-mentioned 2nd Embodiment.

  As shown in FIG. 6A, the contracted intermediate elastic body 17 has a shape along the inner peripheral wall portion 12a. Thereby, in the cross section orthogonal to the main flow direction, the flow path wall on the inner peripheral wall portion 12a side can be formed in a substantially linear shape extending in the width direction by the hollow elastic body 17. In this case, the channel wall in the elbow 12 in the cross section has a substantially rectangular shape as a whole.

  On the other hand, as shown in FIG. 6B, the expanded hollow elastic body 17 forms a protruding wall 24 that protrudes toward the outer peripheral wall portion 12b. As a result, on both sides in the width direction of the protruding wall 24, the flow path wall on the side of the inner peripheral wall portion 12a becomes recessed toward the inner peripheral side (upper side in FIG. 6B), and in the cross section orthogonal to the main flow direction, The flow path wall can be roughly similar to the shape shown in FIG. 4B in the second embodiment described above.

Similarly to the second embodiment, when the hollow elastic body 17 is expanded, the elbow 12 has a protruding dimension of the protruding wall 24 as h and a dimension from the inner peripheral wall part 12a to the outer peripheral wall part 12b as H. sometimes,
0 <h / H <0.3
It is preferable that More specifically, the dimension h indicates the distance between the portion of the wall surface of the inner peripheral wall portion 12a located on the innermost peripheral side (the upper side in FIG. 6B) and the lower end of the protruding wall 24.

  During power generation operation at the design point, as shown in FIG. 6B, fluid is supplied and filled in the internal space 16. As a result, the pressure of the fluid in the internal space 16 increases, and the hollow elastic body 17 expands. At this time, the flow path wall in the elbow 12 can be made substantially similar to the shape shown in FIG. 4B in the second embodiment described above.

  On the other hand, at the time of low flow operation, as shown in FIG. 6A, the fluid is discharged from the internal space 16, and the pressure of the fluid in the internal space 16 becomes low. As a result, the hollow elastic body 17 contracts under the pressure of the water flow. At this time, the flow path wall in the elbow 12 can be roughly shaped similar to the shape shown in FIG. 4A in the second embodiment described above.

  Thus, according to the present embodiment, the hollow elastic body 17 can be expanded by supplying the fluid to the internal space 16. As a result, the hollow elastic body 17 can form the protruding wall 24, and in the cross section orthogonal to the main flow direction, the flow path wall in the elbow 12 is schematically shown in FIG. 4B in the second embodiment described above. The shape can be the same as the shape shown in FIG. For this reason, generation | occurrence | production of the hydraulic loss resulting from the peeling flow in the suction pipe 8 and a hydraulic pressure vibration can be suppressed in a design point.

  Further, according to the present embodiment, the hollow elastic body 17 can be contracted by discharging the fluid from the internal space 16. Thereby, in the cross section orthogonal to the main flow direction, the flow path wall on the side of the inner peripheral wall portion 12a can be formed in a substantially linear shape extending in the width direction. For this reason, at the time of low flow rate operation or high flow rate operation, it is possible to suppress the occurrence of vortices on the downstream side in the swirl flow direction with respect to the protruding wall 24 and to suppress hydraulic loss.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof. Moreover, as a matter of course, these embodiments can be partially combined as appropriate within the scope of the present invention.

  Furthermore, in the above-described embodiment, the Francis turbine has been described as an example of the hydraulic machine. However, the hydraulic machine is not limited to this, and any hydraulic machine including a suction pipe device having an elbow (bent pipe) may be used. The suction pipe device of the hydraulic machine according to the present invention can also be applied to a hydraulic machine other than the Francis turbine.

DESCRIPTION OF SYMBOLS 5 Runner 8A Suction pipe apparatus 10 Upper draft 11 Expansion pipe 12 Elbow 12a Inner peripheral wall part 12b Outer peripheral wall part 13 Projection wall 16 Internal space 17 Hollow elastic body 20 Fluid supply / discharge part 21 Fluid storage part 22 Pump 24 Projection wall

Claims (2)

A suction pipe device of a hydraulic machine for flowing the water flow that has passed through a runner that is rotationally driven by an inflowing water flow,
An upper tube disposed on the runner side;
An expansion tube disposed on the opposite side of the runner;
A bent pipe that connects the upper pipe and the expansion pipe and bends the flow path of the water flow, and has a inner peripheral wall portion and an outer peripheral wall portion;
The water stream is a hollow elastic body having a partitioned internal space;
A fluid supply / discharge portion that supplies and discharges fluid to and from the internal space of the hollow elastic body ,
A protruding wall that protrudes toward the outer peripheral wall portion is provided at a central portion in the width direction of the inner peripheral wall portion of the bent pipe ,
The suction pipe device for a hydraulic machine, wherein the hollow elastic body is provided on both sides of the protruding wall in the width direction . In a cross section perpendicular to the main flow direction of the water flow, when the projecting dimension of the projecting wall is h, and the dimension from the inner peripheral wall part to the outer peripheral wall part is H,
0 <h / H <0.3
The suction pipe device for a hydraulic machine according to claim 1, wherein:

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