JP6523857B2 - Runner and hydraulic machine - Google Patents

Description

  Embodiments of the present invention relate to a runner and a hydraulic machine.

  The Francis turbine is known as an example of a hydraulic machine. In a general Francis turbine, a runner is fixed to the lower end of the water turbine main shaft, and a plurality of guide vanes and stay vanes are circumferentially arranged side by side in a parallel flow path formed on the outer peripheral side of the runner . Moreover, a casing is arrange | positioned at the outer peripheral side of a stay vane. In this configuration, the water led from the hydraulic iron pipe flows through the casing all around the plurality of stay vanes. Water flowing out of the stay vanes is guided to the runner through the guide vanes to rotationally drive the runner. As a result, the water turbine main shaft rotates, and the generator connected to the water turbine main shaft is driven. On the other hand, the water which rotated the runner is discharged to the lower pond through the suction pipe. In addition, by changing the opening degree of the guide vanes at the time of water wheel operation, the amount of water flowing into the runner can be adjusted, and the amount of power generation can be changed.

  Since the runner blades in the runner of the Francis turbine are fixed blades, the collision loss is small and the most efficient when the relative angle β1 of the flow from the guide vane to the runner coincides with the inlet angle βb of the runner blades. However, the Francis turbine is not always operated at the optimal operating condition because it is operated at various operating conditions which deviate from such a most efficient design point.

  FIG. 7 shows the flow in the high-fall operation away from the design point, and FIG. 8 shows the flow in the low-fall operation off the design point. In FIG. 7 and FIG. 8, Cu1 indicates the circumferential velocity of the runner, Cv1 indicates the absolute velocity of the flow, and Cw1 indicates the relative velocity of the flow. The relative angle β1 is determined from the circumferential velocity Cu1 and the relative velocity Cw1. Also, Rd indicates the rotation direction of the runner.

  For example, as shown in FIG. 7, at the high-falling operating point, the relative angle β1 of the flow flowing into the runner blade 40 of the runner becomes larger than the inlet angle βb of the runner blade 40, resulting in a flow angle mismatch. As a result, cavitation ca is easily generated on the inlet side of the negative pressure surface 40 n of the runner blade 40. Such cavitation may cause corrosion of the water surface of the runner blades, which is a problem in terms of equipment reliability.

  Further, as shown in FIG. 8, at the operating point on the low drop side, the relative angle β1 of the flow flowing into the runner blade 40 of the runner becomes smaller than the inlet angle βb of the runner blade 40, causing a mismatch in flow angle. As a result, the separation vortex wh is easily generated from the pressure surface 40 p side of the runner blade 40. Such separation vortices are accompanied by a popping sound unlike cavitation that may occur in high-end operation. Even if this separation vortex is generated, it does not lead to harmful erosion unless it extends downstream and adheres to, for example, the running surface of the other runner blades. Therefore, peeling vortices do not pose a major problem compared to cavitation. However, in the case where the separation vortex adheres to the flowing water surface or is accompanied by noise, it is desirable to design the runner appropriately so that the generation limit does not fall within the normal operation range as much as possible.

  The generation limit of cavitation and separation vortices as described above can be shown on the water turbine performance chart as an initial line and may be used as a standard for limiting the operation. FIG. 10 shows an example of a typical Francis turbine water turbine performance diagram. In this diagram, the horizontal axis shows a drop and the vertical axis shows a flow rate. An alternate long and short dash line L11 indicates an initial line of cavitation on the inlet side of the negative pressure surface of the runner blade, and an alternate long and short dash line L12 indicates an initial line of separation vortex on the inlet side of the pressure surface of the runner blade. Also, a plurality of broken lines indicate equal efficiency lines. In the diagram shown in FIG. 10, a part of the hatched operating range includes the ranges indicated by two primary lines L11 and L12, and cavitation and peeling vortices occur at such operating points. Driving may be limited due to fear.

  Francis turbines are particularly high-speed, low-head-flow, high-specific-speed type water turbines, when operation is required under conditions where the water level changes in the dam are large to increase operation efficiency, and the output change width It is required to suppress the occurrence of cavitation and peeling vortices when it is required to increase the operating range of the device by enlarging it.

  For example, as one of the measures, as shown by the broken line in FIG. 9, the inlet side of the negative pressure surface of the runner blade 40 has a shape (code 40a) expanded more than the normal shape (the shape shown by the solid line in the figure). Can be mentioned. With regard to such a bulging portion, conventionally, techniques etc. have been proposed for reducing the hydraulic loss and suppressing the peeling by defining the shape by numerical limitation.

JP, 2006-291865, A Patent No. 4094495

  However, as a measure to suppress the occurrence of cavitation and peeling vortices, even if the swelling portion is formed on the inlet side of the suction surface of the runner blade as described above, the flow changes rapidly downstream from the most overhanging portion Because cavitation often occurs, it is difficult to completely suppress cavitation. In particular, in the high specific velocity type runner, since the blade length from the inlet to the outlet of the runner blade is short, the load is high at the inlet and cavitation suppression becomes more difficult than in the low specific velocity type runner. In addition, when defining the shape of the bulging portion, it is necessary to search for the optimum shape in a trial and error manner taking into consideration the influence of the curvature of the band surface shape of the runner, etc., which takes time for design.

  In addition, when the bulging portion is formed on the inlet side of the suction surface of the runner blade, although cavitation that may occur in the high-fall operation can be suppressed, both cavitation on the high-fall side and peeling vortices on the low-fall side It is difficult to suppress.

  The present invention has been made in view of such circumstances, and a runner and a hydraulic machine capable of sufficiently expanding the operating range of a hydraulic machine by effectively suppressing the occurrence of cavitation and / or peeling vortices. Intended to provide.

The runner according to the embodiment is a runner of a hydraulic machine, and is a blade body, and an inlet-side blade forming member provided inside the inlet side of the blade body and exposing a part of the blade body to the outside. And a runner blade having The part of the inlet-side blade forming member exposed to the outside of the blade main body forms an inlet side water surface continuous with a negative pressure surface or a pressure surface of the blade main body. The inlet-side blade forming member is formed to change the shape of the inlet-side water surface in response to a change in pressure around it.
Moreover, the hydraulic machine by embodiment is provided with the said runner.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of cavitation and / or peeling vortices can be suppressed effectively and the operating range of a hydraulic machine can fully be expanded.

1 is a schematic view of a Francis turbine according to a first embodiment. It is a sectional view which meets a diameter direction of a runner blade in a runner of a Francis turbine concerning a 1st embodiment. It is sectional drawing in alignment with the radial direction of the runner blade | wing in the runner of the Francis turbine concerning 2nd Embodiment. It is sectional drawing in alignment with the radial direction of the runner blade | wing in the runner of the Francis turbine concerning 3rd Embodiment. It is sectional drawing in alignment with the radial direction of the runner blade | wing in the runner of the Francis turbine concerning 4th Embodiment. It is a water turbine performance diagram for demonstrating the effect of each embodiment. It is a figure explaining the relationship between the relative angle of the flow in the high drop side driving | operation of a general Francis turbine, and the inlet angle of a runner blade, Comprising: It is the figure which showed a mode that cavitation generate | occur | produced. It is a figure explaining the relationship between the relative angle of the flow in the low head side operation of a general Francis turbine, and the entrance angle of a runner blade, and is a figure showing a situation of generation of exfoliation vortices. It is a figure which shows the runner blade | wing formed in the shape which expanded the inlet side of the suction surface. It is the figure which showed an example of the water turbine performance diagram of a general Francis turbine.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the respective embodiments, the same reference numerals are used for the same components as the common Francis turbine described with reference to FIGS. 7 to 10 and the common matters.

First Embodiment
FIG. 1 shows a Francis turbine 100 as a hydraulic machine according to a first embodiment of the present invention. The Francis turbine 100 includes a spiral casing 1 in which water flows in from the upper pond (not shown) through an iron pipe, a plurality of stay vanes 2, a plurality of guide vanes 3, and a runner 4. A parallel flow path consisting of an upper cover and a lower cover (not shown) is formed between the casing 1 and the runner 4 disposed on the inner peripheral side, and a plurality of stay vanes 2 and a parallel flow path are formed in this parallel flow path. A plurality of guide vanes 3 are arranged. The runner 4 is provided rotatably with respect to the casing 1 about the rotation axis C1.

  The plurality of stay vanes 2 are for guiding water flowing out of the casing 1 to the guide vanes 3, and on the inner circumferential side of the casing 1, a predetermined distance in the circumferential direction (hereinafter referred to as circumferential direction) with respect to the rotation axis C1. It is placed open. The plurality of guide vanes 3 are for guiding the inflowing water to the runner 4, and are arranged at predetermined intervals in the circumferential direction on the inner peripheral side of the stay vane 2. Each of the guide vanes 3 is rotatable, and the amount of water flowing into the runner 4 can be adjusted by changing the degree of opening.

  The runner 4 has a crown 11, a band 12, and a plurality of runner blades 13 provided between the crown 11 and the band 12. The plurality of runner blades 13 are arranged at predetermined intervals in the circumferential direction.

  A generator 7 is connected to the runner 4 via a water wheel main shaft 6, and the generator 7 generates power by being rotated by the runner 4. Further, on the downstream side of the runner 4, a suction pipe 5 is provided. The water flowing out of the runner 4 is discharged to the lower pond through the suction pipe 5.

  As shown in FIG. 2, the runner blade 13 in the present embodiment is provided inside the blade body 14 and the inlet side of the blade body 14 (that is, the inflow side of water at the time of water wheel operation). And an inlet-side blade forming member 15 exposed to the outside of the main body 14. In the present embodiment, a part of the inlet-side blade forming member 15 exposed to the outside of the blade main body 14 forms an inlet-side water surface 15 n continuous with the negative pressure surface 14 n of the blade main body 14. That is, the negative pressure surface of the runner blade 13 is configured by the negative pressure surface 14 n of the blade main body 14 and the inlet-side flowing water surface 15 n.

  On the other hand, the other part of the inlet-side vane forming member 15 different from the inlet-side flowing water surface 15 n is covered with the inner surface of the accommodation portion 14 C for accommodating the inlet-side vane forming member 15 formed in the vane main body 14. It is in a state of In the present embodiment, the housing portion 14C is formed in an elongated shape in which the longitudinal direction extends in the flowing direction of the blade main body 14 in a cross-sectional view along the radial direction of the runner 4 and is open on the negative pressure surface side. The inlet-side blade forming member 15 is fixed by press-fitting or the like in the housing portion 14C, and the dropout from the blade main body 14 is prevented.

  In the present embodiment, the inlet-side blade forming member 15 is formed of a hollow elastic body, and the longitudinal direction of the blade body 14 in the flowing water direction is a cross-sectional view along the radial direction of the runner 4 so as to be aligned with the accommodation portion 14C. It is formed in a substantially rectangular shape extending and has an internal space 16. The internal space 16 is sealed and its pressure is set to a first predetermined value.

  As an example, the first predetermined value described above is operated by the Francis turbine 100 at the most efficient design point (design head and design flow rate) at which the relative angle of the flow entering the runner 4 matches the inlet angle of the runner blade 13 The pressure value of the water flowing on the negative pressure surface 14 n side is the same value as that of the negative pressure surface. In the present embodiment, in order to set the pressure of the internal space 16 to such a first predetermined value, the fluid (air, high-pressure water, etc.) whose pressure is adjusted is sealed in the internal space 16 in advance. In the runner 4, a control mechanism may be provided to adjust the pressure of the internal space 16 to an arbitrary value.

  Such an inlet side blade forming member 15 is formed to change the shape of the inlet side water surface 15n in accordance with the pressure change around it. Specifically, the inlet side vane forming member 15 has a shape of the inlet side water surface 15n on the side in contact with the main flow of water, for example, according to the relationship (difference) between the surrounding pressure condition and the pressure condition of the internal space 16 as shown in FIG. It is possible to change to the state shown by the broken line. In addition, the inlet-side water surface 15n of the present embodiment and the negative pressure surface 14n of the blade main body 14 are smooth as shown by the solid line in FIG. It is configured to be continuous and streamlined.

  The operation of the present embodiment will be described.

  In the Francis turbine 1 according to the present embodiment, the water led from the upper pond is led to the casing 1 through the iron pipe. The water is homogenized in the circumferential direction by the casing 1 and flows into the runner 4 through the stay vanes 2 and the guide vanes 3 disposed on the inner peripheral side of the casing 1. The runner 4 is rotated by the pressure energy of the passing water, and drives the generator 7 connected via the water wheel main shaft 6. Thus, the generator 7 generates power. Water flowing out of the runner 4 is discharged to the lower pond through the suction pipe 5.

  When the Francis turbine 100 is operated with the design head and the design flow rate, the pressure of the internal space 16 of the inlet-side blade forming member 15 and the pressure of the water flowing on the negative pressure surface 14 n balance each other. As shown by the solid line, the inlet side water surface 15n and the suction surface 14n of the blade body 14 are smoothly and continuously streamlined.

  On the other hand, when it becomes the high drop side operation point, as shown in FIG. 2, the relative angle β1 of the flow flowing into the runner blade 13 becomes larger than the inlet angle βb of the runner blade 13 and the flow angle mismatch As a result, the pressure on the inlet side of the suction surface 14 n in the runner blade 13, that is, the pressure around the inlet water surface 15 n is reduced. At this time, the pressure in the internal space 16 of the inlet-side vane forming member 15 is higher than the pressure around the inlet-side water surface 15n, so the inlet-side water surface 15n is the mainstream water as shown by the broken line in FIG. Get out to the side. At the time of extension, the shape of the inlet side water surface 15n deforms along the flow around it.

  Thus, according to the present embodiment, when the inlet angle βb of the runner blade 13 approaches the relative angle β1 as shown by the arrow A1 in the figure, the occurrence of cavitation due to the mismatch of the flow angles is suppressed. In addition, the shape of the inlet side water surface 15n is deformed along the flow around the inlet side water surface, so that rapid pressure changes are prevented before and after the inlet side water surface 15n, thereby, in particular, the inlet side water surface The occurrence of cavitation on the downstream side of 15 n is suppressed.

  Therefore, according to the present embodiment, the occurrence of cavitation can be effectively suppressed, and the operating range of the Francis turbine 100, which is a hydraulic machine, can be sufficiently expanded. FIG. 6 shows a water turbine performance diagram for explaining the operation and effect of the present embodiment. In FIG. 6, an alternate long and short dash line L11 indicates an initial line of cavitation when the inlet-side blade forming member 15 is not provided, and an alternate long and short dash line L12 indicates an initial line of separation vortex. Specifically, according to the present embodiment, the primary line L11 of FIG. 6 can be separated to the high drop side as the primary line L1 of the solid line in the figure. As a result, the operating range can be expanded more widely as shown by the arrow α in the figure.

  In the present embodiment, by providing the inlet-side blade forming member 15 on the negative pressure surface side, cavitation that may occur in the high-fall operation can be suppressed, but the shape of the blade main body 14 is the low-fall operation. The inlet-side blade forming member 15 may be combined with such a blade main body 14 by forming into a shape capable of suppressing a separation vortex which may occur. In this case, it is possible to suppress the occurrence of cavitation that may occur on the high drop side and the generation of separation vortices that may occur on the low drop side, and the operating range can be expanded more widely.

Second Embodiment
Next, a second embodiment will be described. The same components as the components of the first embodiment in the present embodiment are assigned the same reference numerals and descriptions thereof will be omitted. In addition, a part of description of the same operation and effect as the first embodiment is also omitted.

  As shown in FIG. 3, in the present embodiment, the communication passage 18 communicating the internal space 16 from the portion of the pressure surface 14 p of the blade main body 14 facing the inlet side blade forming member 15 in the blade thickness direction is It is formed across the blade main body 14 and the inlet side blade forming member 15. In other words, it extends from the portion of the pressure surface 14 p of the blade main body 14 facing the inlet-side blade forming member 15 in the blade thickness direction to the internal space 16 to circulate water between the pressure surface 14 p and the internal space 16. A communication passage 18 to be allowed is formed across the blade main body 14 and the inlet side blade forming member 15.

  The communication passage 18 includes a first hole 18A extending from the pressure surface 14p to the housing 14C, and a second hole 18B formed in a surface of the inlet-side blade forming member 15 facing the pressure surface 14p. It is done. The first hole 18A and the second hole 18B are continuous with each other.

  Therefore, the internal space 16 is not sealed but is open to the pressure surface 14p. Thereby, when the Francis turbine 100 is operated, the water on the pressure surface 14 p side of the blade main body 14 flows into the internal space 16. Further, in the state where water on the pressure surface 14 p side flows into the internal space 16 at the time of operation of the Francis turbine 100 at the design head difference and the design flow rate, the inlet side flowing water surface 15 n and the suction surface 14 n of the blade main body 14 in this embodiment. As shown by a solid line in FIG. 3, it is configured so as to form a smooth and continuous streamline.

  The operation of the present embodiment will be described.

  In the present embodiment, when the high drop side operation point is reached, as shown in FIG. 3, the relative angle β1 of the flow flowing into the runner blade 13 becomes larger than the inlet angle βb of the runner blade 13 and the flow Due to the angle mismatch, the pressure around the inlet side of the suction surface 14 n, ie, the inlet side water surface 15 n in the runner blade 13 is reduced. At this time, the pressure of the water flowing into the inner space 16 of the inlet-side blade forming member 15 is higher than the pressure around the inlet-side water surface 15n, so the inlet-side water surface 15n is a broken line in FIG. As shown, push into the mainstream water side. At the time of extension, the shape of the inlet side water surface 15n is deformed to follow the flow around it, as in the first embodiment.

  Thus, according to the present embodiment, the occurrence of cavitation due to the mismatch of the flow angles is suppressed by the fact that the inlet angle βb of the runner blade 13 approaches the relative angle β1 even in the high-fall operation. In addition, the shape of the inlet side water surface 15n is deformed along the flow around the inlet side water surface, so that rapid pressure changes are prevented before and after the inlet side water surface 15n, thereby, in particular, the inlet side water surface The occurrence of cavitation on the downstream side of 15 n is suppressed.

  On the other hand, when the operating point on the low head side is reached, as shown in FIG. 8, the relative angle β1 of the flow flowing into the runner blade 13 becomes smaller than the inlet angle βb of the runner blade 13, and the flow angle Due to the mismatch, the flow separates at the inlet side of the pressure surface 14p at the runner blade 13, and the pressure around the inlet side of the pressure surface 14p drops sharply. At this time, the pressure of the water flowing into the inner space 16 of the inlet-side blade forming member 15 also decreases, and the pressure around the inlet-side water surface 15n becomes higher than the pressure of the water in the inner space 16. The side water surface 15n is indented toward the pressure surface 14p.

  Thereby, according to the present embodiment, even in the low-fall operation, the generation of the separation vortex due to the mismatch of the flow angles is suppressed by the fact that the inlet angle βb of the runner blade 13 approaches the relative angle β1. .

  Therefore, in the present embodiment, the occurrence of cavitation and separation vortices can be effectively suppressed, and the operating range of the Francis turbine 100, which is a hydraulic machine, can be sufficiently expanded. Specifically, according to the present embodiment, the primary line L11 of FIG. 6 can be separated to the high drop side as the primary line L1 of the solid line in the figure. Further, the primary line L12 can be separated to the low drop side as shown by the solid primary line L2 in the figure. As a result, the operating range can be expanded more widely, as shown by the arrows α and β in the figure.

  Moreover, in the present embodiment, since the pressure surface 14p of the blade main body 14 and the internal space 16 communicate with each other, the pressure on the inlet side water surface 15n can be appropriately adjusted without adjusting the pressure of the internal space 16 according to the operating condition. The shape changes. Therefore, since there is no need to install an operation for adjusting the pressure in the internal space 16 or a mechanism for adjusting the pressure, it is possible to obtain an advantage regarding the manufacturing cost.

Third Embodiment
Next, a third embodiment will be described. The same components as the components of the first and second embodiments in the present embodiment are given the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 4, also in the present embodiment, the runner blade 13 is provided inside the blade body 14 and the inlet side of the blade body 14, and the inlet side that exposes a part thereof to the outside of the blade body 14. A part of the inlet side blade forming member 15 exposed to the outside of the blade body 14 forms an inlet side water surface 15p continuous with the pressure surface 14p of the blade body 14; There is. That is, the pressure surface of the runner blade 13 is constituted by the pressure surface 14 p of the blade main body 14 and the inlet-side water surface 15 p.

  The inlet-side blade forming member 15 in the present embodiment is formed of a hollow elastic body, and the blade main body 14 is viewed in cross section along the radial direction of the runner 4 so as to be aligned with the accommodation portion 14C formed in the blade main body 14 It is formed in a substantially rectangular shape in which the longitudinal direction extends in the flowing water direction, and has an internal space 16. The internal space 16 is sealed and its pressure is set to a second predetermined value. The housing portion 14C in the present embodiment is open to the pressure surface side.

  As the second predetermined value, as an example, the Francis turbine 100 is operated at the most efficient design point (design head and design flow rate) at which the relative angle of the flow entering the runner 4 matches the inlet angle of the runner blade 13 The pressure value of the water flowing on the pressure surface 14 p side is the same value as the pressure value of the water flowing on the pressure surface 14 p side. In the present embodiment, in order to set the pressure of the internal space 16 to such a second predetermined value, a fluid whose pressure is adjusted in the internal space 16 (air or high pressure as in the first embodiment) Water etc. are enclosed in advance.

  The inlet-side vane forming member 15 in the present embodiment has, for example, the shape of the inlet-side water surface 15p on the side in contact with the main flow of water according to the relationship (difference) between the surrounding pressure conditions and the pressure conditions of the internal space 16, as shown in FIG. It is possible to change to the state shown by the broken line of. The inlet side water surface 15p of this embodiment and the pressure surface 14p of the blade main body 14 are smooth as shown by a solid line in FIG. 4 when the Francis turbine 100 is operated at the design head and the design flow rate. It is configured to be continuous and streamlined.

  The operation of the present embodiment will be described.

  In the present embodiment, when the Francis turbine 100 is operated at the design height and the design flow rate, the pressure of the internal space 16 of the inlet side blade forming member 15 and the pressure of water flowing on the pressure surface 14p side By balancing, as shown by the solid line in FIG. 4, the inlet-side water surface 15 p and the pressure surface 14 p of the blade main body 14 form a smooth and continuous streamline.

  On the other hand, when the operating point is on the low head side, as shown in FIG. 4, the relative angle β1 of the flow flowing into the runner blade 13 becomes smaller than the inlet angle βb (not shown) of the runner blade 13 Due to the flow angle mismatch, the flow separates on the inlet side of the pressure surface 14p in the runner blade 13, and the pressure around the inlet side of the pressure surface 14p, that is, the inlet side water surface 15p drops sharply. At this time, the pressure in the internal space 16 of the inlet-side vane forming member 15 is higher than the pressure around the inlet-side water surface 15p, so the inlet-side water surface 15p is the mainstream water as shown by the broken line in FIG. Get out to the side. At the time of extension, the shape of the inlet side water surface 15p deforms along the flow around it.

  Thereby, according to the present embodiment, the generation of the separation vortex due to the mismatch of the flow angles is suppressed by the fact that the inlet angle βb of the runner blade 13 approaches the relative angle β1 as shown by the arrow A2 in the figure. Further, the shape of the inlet side water surface 15p is deformed along the flow around the inlet side water surface, so that the occurrence of a rapid pressure change before and after the inlet side water surface 15p is alleviated.

  Therefore, according to the present embodiment, it is possible to effectively suppress the generation of the separation vortex and sufficiently expand the operating range of the Francis turbine 100 which is a hydraulic machine. Specifically, according to the present embodiment, the primary line L12 of FIG. 6 can be separated to the low drop side as the primary line L2 of the solid line in the figure. As a result, the operating range can be expanded more widely as shown by the arrow β in the figure.

Fourth Embodiment
Next, a fourth embodiment will be described. The same components as the components of the first to third embodiments in the present embodiment are assigned the same reference numerals and explanation thereof is omitted. In addition, a part of the description will be omitted also regarding the same operation and effect as the third embodiment.

  The inlet-side vane forming member 15 of the present embodiment is provided at the same position as that of the third embodiment. On the other hand, as shown in FIG. 5, in the present embodiment, the communication passage 18 communicating the internal space 16 from the portion of the suction surface 14n of the blade main body 14 facing the inlet side blade forming member 15 in the blade thickness direction. Is formed straddling the blade body 14 and the inlet-side blade forming member 15.

  The communication passage 18 includes a first hole 18A extending from the suction surface 14n to the housing 14C, and a second hole 18B formed in a surface of the inlet-side blade forming member 15 facing the suction surface 14n. It is done. The first hole 18A and the second hole 18B are continuous with each other.

  Therefore, the internal space 16 is not sealed but is open to the negative pressure surface 14 n side. Thus, when the Francis turbine 100 is in operation, water on the negative pressure surface 14 n side of the blade main body 14 flows into the internal space 16. Further, in the state where water on the negative pressure surface 14 n side flows into the internal space 16 during operation of the Francis turbine 100 at the design head difference and the design flow rate, between the inlet side flowing water surface 15 p of this embodiment and the pressure surface 14 p of the blade main body 14. As shown by a solid line in FIG. 5, it is configured so as to form a smooth and continuous streamline.

  The operation of the present embodiment will be described.

  In the present embodiment, when the operating point on the low head side is reached, as shown in FIG. 5, the relative angle β1 of the flow flowing into the runner blade 13 is greater than the inlet angle βb (not shown) of the runner blade 13 As the flow angle becomes smaller and the flow angle mismatches, the flow separates at the inlet side of the pressure surface 14p in the runner blade 13, and the pressure around the inlet side of the pressure surface 14p, that is, the inlet side water surface 15p drops sharply. At this time, the pressure in the internal space 16 of the inlet-side vane forming member 15 is higher than the pressure around the inlet-side water surface 15p, so the inlet-side water surface 15p is the mainstream water as shown by the broken line in FIG. Get out to the side. At the time of extension, the shape of the inlet side water surface 15p deforms along the flow around it.

  Thus, according to the present embodiment, even in the low-drop operation, as in the third embodiment, the inlet angle βb of the runner blade 13 is a relative angle β1 as shown by the arrow A2 in the figure. As a result, the generation of separation vortices due to the flow angle mismatch is suppressed. Further, the shape of the inlet side water surface 15p is deformed along the flow around the inlet side water surface, so that the occurrence of a rapid pressure change before and after the inlet side water surface 15p is alleviated.

  On the other hand, when it becomes the high drop side operation point, as shown in FIG. 7, the relative angle β1 of the flow flowing into the runner blade 13 becomes larger than the inlet angle βb of the runner blade 13 and the flow angle The mismatch reduces the pressure around the inlet side of the suction surface 14 n in the runner blade 13. At this time, the pressure of the water flowing into the inner space 16 of the inlet-side blade forming member 15 also decreases, and the pressure around the inlet-side water surface 15p becomes higher than the pressure of the water in the inner space 16. The side water surface 15p is indented toward the negative pressure surface 14n side.

  Thus, according to the present embodiment, the occurrence of cavitation due to the mismatch of the flow angles is suppressed by the fact that the inlet angle βb of the runner blade 13 approaches the relative angle β1 even in the high-fall operation.

  Therefore, according to the present embodiment, the occurrence of cavitation and separation vortices can be effectively suppressed, and the operating range of the Francis turbine 100, which is a hydraulic machine, can be sufficiently expanded. Specifically, according to the present embodiment, the primary line L11 of FIG. 6 can be separated to the high drop side as the primary line L1 of the solid line in the figure. Further, the primary line L12 can be separated to the low drop side as shown by the solid primary line L2 in the figure. As a result, the operating range can be expanded more widely, as shown by the arrows α and β in the figure.

  As mentioned above, although embodiment of this invention was described, said embodiment is shown as an example, and it is not intending limiting the range of invention. This novel embodiment can be implemented in other various forms, and various omissions, replacements and changes can be made without departing from the scope of the invention. While this embodiment and its modification are included in the range and subject matter of invention, they are included in the invention indicated to the claim, and the equivalent range.

  For example, in each of the embodiments described above, the inlet-side blade forming member 15 has the internal space 16, but instead, the inlet-side blade forming member 15 is a solid having substantially no internal space. It may be formed of an elastic body that expands and contracts in response to changes in pressure around it. A porous elastic body etc. are mentioned as an example of such a member.

Reference Signs List 1 casing, 2 stay vane, 3 guide vane, 4 runner, 5 suction pipe, 6 water turbine main shaft, 7 generator, 11 crown, 12 band, 13 runner blade, 14 blade main body, 14C housing portion, 14n negative pressure surface, 14p pressure surface , 15 inlet side blade forming member, 15n inlet side water surface, 15p inlet side water surface, 16 internal space, 18 communication passage, 18A first hole, 18B second hole, 100 Francis turbine (hydraulic machine).

Claims (5)

It is a runner of a hydraulic machine,
A runner blade having a blade body, and an inlet-side blade forming member provided inside the inlet side of the blade body and exposing a part of the blade body to the outside;
Wherein the portion that is exposed to the outside of the blade body of said inlet-side blade formation member forms an inlet-side flow water surface continuous to the negative pressure surface of the blade body,
The inlet-side blade forming member has a sealed internal space, and the pressure of the internal space is set to a predetermined value,
The inlet side blade forming member is formed to change a shape of the inlet side water surface according to a pressure change around the inlet side blade forming member. It is a runner of a hydraulic machine,
A runner blade having a blade body, and an inlet-side blade forming member provided inside the inlet side of the blade body and exposing a part of the blade body to the outside;
Wherein the portion that is exposed to the outside of the blade body of said inlet-side blade formation member forms an inlet-side flow water surface continuous to the negative pressure surface of the blade body,
The inlet side vane forming member has an internal space,
A communication passage communicating the internal space from the pressure surface of the blade body is formed straddling the blade body and the inlet-side blade forming member,
The inlet side blade forming member is formed to change a shape of the inlet side water surface according to a pressure change around the inlet side blade forming member . It is a runner of a hydraulic machine,
A runner blade having a blade body, and an inlet-side blade forming member provided inside the inlet side of the blade body and exposing a part of the blade body to the outside;
The part of the inlet-side blade forming member exposed to the outside of the blade main body forms an inlet side water surface continuous with the pressure surface of the blade main body,
The inlet-side blade forming member has a sealed internal space, and the pressure of the internal space is set to a predetermined value,
The inlet side blade forming member is formed to change a shape of the inlet side water surface according to a pressure change around the inlet side blade forming member . It is a runner of a hydraulic machine,
A runner blade having a blade body, and an inlet-side blade forming member provided inside the inlet side of the blade body and exposing a part of the blade body to the outside;
The part of the inlet-side blade forming member exposed to the outside of the blade main body forms an inlet side water surface continuous with the pressure surface of the blade main body,
The inlet side vane forming member has an internal space,
A communication passage communicating the internal space from the suction surface of the blade main body is formed straddling the blade main body and the inlet side blade forming member,
The inlet side blade forming member is formed to change a shape of the inlet side water surface according to a pressure change around the inlet side blade forming member .
The runner according to claim 1, characterized in that. A hydraulic machine comprising the runner according to any one of claims 1 to 4 .

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