Runners and hydraulic machinery

Abstract

The problem that this invention aims to solve is to provide a runner for a hydraulic machine that can reduce runner losses. [Solution] In order to achieve the above objectives, the runner of the hydraulic machine of this embodiment is characterized in that, of the inlet end of the runner blade provided between the crown and the band, at least one of the following is formed: a crown-side curved portion formed on the crown side of the inlet end and curving radially inward toward the crown-side connection point, which is the connection point between the inlet end and the crown; and a band-side curved portion formed on the band side of the inlet end and curving radially inward toward the band-side connection point, which is the connection point between the band and the inlet end.

Description

Technical Field

[0001] Embodiments of the present invention relate to a runner of a hydraulic machine and a hydraulic machine.

Background Art

[0002] During the operation of a Francis turbine, which is a type of hydraulic machine, water flowing from an upper pond through a penstock into a casing enters the runner through the casing, stay vanes, and guide vanes. When the runner is rotationally driven by the water flowing into it, a generator connected to the runner via a main shaft is driven to generate electricity. Subsequently, the water that has rotationally driven the runner flows out from the runner through a draft tube into a lower pond or a discharge channel.

[0003] FIG. 7 is a schematic configuration diagram around a runner 110 provided in a conventional Francis turbine 100. As shown in FIG. 7, the conventional runner 110 includes a crown 130 connected to a main shaft 120 to transmit the rotational energy of the runner 110 to a generator (not shown), a band 140 provided on the outer side and at an opposing position of the crown 130, and a plurality of runner blades 150 provided at regular intervals in the circumferential direction between the crown 130 and the band 140. The runner blades 150 form a water flow path between adjacent runner blades 150, have an inlet end 170 on the guide vane 160 side (upstream side), and an outlet end 190 on the draft tube 180 side (downstream side). That is, the runner blades 150 are formed such that water flowing into the inlet end 170 flows out from the outlet end 190. Further, the runner blades 150 are configured to rotate by receiving pressure from the water flowing into the inlet end 170. That is, the runner blades 150 are configured to convert the pressure energy received from the water flowing into the inlet end 170 into rotational energy for rotationally driving the generator.

[0004] Figure 8 is a cross-sectional view taken along the line AA in Figure 7. Figure 8 shows the velocity triangle near the point of maximum efficiency at the inlet end 170 of the runner blade 150. As shown in Figure 8, the velocity triangle at the inlet end 170 is represented by the circumferential velocity U1, which is the circumferential velocity component of the inlet end 170; the absolute velocity V1, which is the actual velocity component of the water flowing into the inlet end 170; the relative velocity W1, which is the relative velocity component of the water with respect to the circumferential velocity U1; and the meridian velocity Vm1, which is the velocity component that serves as a design indicator for determining the water flow velocity. The direction of the relative velocity W1, i.e., the angle β1 (relative angle β1) between the relative velocity W1 and the meridian velocity Vm1, is often designed to approximately coincide with the angle β0 (inlet angle β0) between the radius R1 of the runner 110 and the camber line 170a of the inlet end 170.

[0005] Figure 9 is an enlarged view of region B in Figure 7. As shown in Figure 9, between the guide vane 160 and the inlet end 170, there is a region C where the effect of friction with the wall surface is large, located near the wall surface on the crown 130 side and near the wall surface on the band 140 side. In addition, there is a region D where the effect of friction with the wall surface is small, located away from the wall surface on the crown 130 side and the wall surface on the band 140 side. The velocity of water flowing in region C tends to be slower due to the effect of friction, while the velocity of water flowing in region D tends to be faster as it is less affected by friction.

[0006] Figure 10 is a cross-sectional view taken along the EE arrow in Figure 7. In the case of the upper panel, the velocity triangle in region D (near the point of highest efficiency) in Figure 9 is often the same as the velocity triangle shown by the dotted line in Figure 10 (equivalent to the velocity triangle shown in Figure 8). However, the velocity triangle in region C (not near the point of highest efficiency) in Figure 9 may be the same as the velocity triangle shown by the solid line in Figure 10. That is, although the periphery velocity U2 is the same as the periphery velocity U1, the absolute velocity V2 and meridian velocity Vm2 are smaller than the absolute velocity V1 and meridian velocity Vm1 due to the effect of friction with the wall. As a result, the relative velocity W2 becomes larger, and the angle β2 (relative angle β2) between the relative velocity W2 and the meridian velocity Vm2 becomes larger than the relative angle β1. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 6132708 [Patent Document 2] Patent No. 6884672 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] As described above, near the wall surface, friction with the wall surface can cause a discrepancy between the relative inflow angle of the water flowing into the runner 110 and the inflow angle β0 of the inlet end 170. This discrepancy could sometimes cause losses in the runner.

[0009] The problem that this invention aims to solve is to provide a runner for a hydraulic machine that can reduce runner losses. [Means for solving the problem]

[0010] The runner of the hydraulic machine according to this embodiment is characterized in that at least one of the following is formed on the crown side of the inlet end of the runner blade provided between the crown and the band, and curves radially inward toward the crown side connection point which is the connection point between the inlet end and the crown, and the band side of the inlet end, and curves radially inward toward the band side connection point which is the connection point between the band and the inlet end. [Brief explanation of the drawing]

[0011] [Figure 1] Cross-sectional view of a Francis-type turbine. [Figure 2] Enlarged view of region P in Figure 1. [Figure 3] Enlarged view of region Q in Figure 2. [Figure 4] Cross-sectional view taken along arrow BB in Figure 2. [Figure 5] Enlarged view of region Q in Figure 2. [Figure 6] A schematic diagram created based on the flow analysis results. [Figure 7] A schematic diagram of the runner area of ​​a conventional Francis turbine. [Figure 8] Cross-sectional view taken along arrow AA in Figure 7. [Figure 9] Enlarged view of region B in Figure 7. [Figure 10] Cross-sectional view taken along arrow EE in Figure 7. [Modes for carrying out the invention]

[0012] Hereinafter, a runner and hydraulic machine according to embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments shown below are illustrative examples of embodiments of the present invention and are not intended to limit the scope of the invention. Furthermore, in the drawings referenced in the embodiments, the same or similar reference numerals are used for identical parts or parts having similar functions, and their descriptions may be omitted. Also, the dimensional ratios in the drawings may differ from the actual ratios, and some components may be omitted from the drawings.

[0013] (First embodiment) A Francis turbine 1, a type of hydraulic machine, will be described using Figures 1 and 2. Figure 1 is a vertical cross-sectional view of the Francis turbine 1. Figure 2 is an enlarged view of region P in Figure 1. As shown in Figure 1, the Francis turbine 1 comprises a casing 2, stay vanes 3, guide vanes 4, runner 5, main shaft 6, generator 7, and draft tube 8. In the following description, the axial direction of the main shaft 6 of the Francis turbine 1 will be referred to as axial direction X, with the upper side of axial direction X simply being referred to as the upper side, and the lower side of axial direction X simply being referred to as the lower side. Furthermore, in the following description, the radially outer side centered on axial direction X will be simply referred to as radially outer, and the radially inner side centered on axial direction X will be simply referred to as radially inner.

[0014] The casing 2 is a volute-shaped member through which water flows in from the upper pond through a penstock (both not shown) during the operation of the waterwheel. The casing 2 guides the water flowing into the casing 2 to the stay vanes 3.

[0015] The stay vanes 3 are members provided on the inner side in the radial direction of the casing 2. A plurality of stay vanes 3 are arranged at regular intervals in the circumferential direction centered on the axial direction X (hereinafter referred to as the circumferential direction). The stay vanes 3 form a water flow path between adjacent stay vanes 3. The stay vanes 3 guide the water flowing into the stay vanes 3 to the guide vanes 4.

[0016] The guide vanes 4 are members provided on the inner side in the radial direction of the stay vanes 3. A plurality of guide vanes 4 are arranged at regular intervals in the circumferential direction. The guide vanes 4 form a water flow path between adjacent guide vanes 4. The guide vanes 4 guide the water flowing into the guide vanes 4 to the runner 5. Further, the guide vanes 4 are configured to be able to change the opening degree by a guide ring (not shown). Thereby, the guide vanes 4 are configured to be able to adjust the flow rate of the water guided to the runner 5 by changing the opening degree.

[0017] The runner 5 is a member provided on the inner side in the radial direction of the guide vanes 4. The runner 5 is connected to the lower end of the main shaft 6 and is configured to be rotatable about the rotation axis X. The runner 5 receives pressure from the water flowing into the runner 5 and is rotationally driven about the rotation axis X. That is, the runner 5 converts the pressure energy of the water received by the runner 5 into rotational energy. The runner 5 includes a crown 10, a band 11, and runner blades 12.

[0018] The crown 10 is a disk-shaped member connected to the main shaft 6. The crown 10 is a member for transmitting the rotational energy of the runner 5 generated by the water flowing into the runner 5 to the main shaft 6.

[0019] The band 11 is an annular member that is connected to the upper end of the suction tube 8 and is positioned radially outward from the crown 10 and opposite to the crown 10.

[0020] The runner blades 12 are multiple components provided between the crown 10 and the band 11 at regular intervals in the circumferential direction. The runner blades 12 form water channels between adjacent runner blades 12. Specifically, as shown in Figure 2, the runner blades 12 have an inlet end 13 on the radially outward side and an outlet end 14 on the radially inward side, and are configured to allow water flowing in from the inlet end 13 to flow out from the outlet end 14. The runner blades 12 are configured to rotate when pressure is applied by the incoming water.

[0021] The main shaft 6 is the rotation axis of the runner 5. The main shaft 6 connects the runner 5 and the generator 7. The main shaft 6 transmits the rotational energy of the runner 5 to the generator 7.

[0022] The generator 7 is a device that generates electricity when the turbine is in operation. The generator 7 is connected to the runner 5 via the main shaft 6. The generator 7 is rotationally driven by the rotational energy of the runner 5 transmitted through the main shaft 6, and generates electricity. The generator 7 may also function as an electric motor and be able to rotate the runner 5 by supplying power. In other words, the Francis turbine 1 may be made capable of pumping water from the lower reservoir (not shown) and releasing it into the upper reservoir (pumping operation).

[0023] The suction pipe 8 is a component located on the lower side of the runner 5. The suction pipe 8 is connected to a lower reservoir or discharge channel (not shown) and discharges the water that flows out of the runner 5 into the lower reservoir or discharge channel.

[0024] Next, the runner blade 12 according to the first embodiment will be further described with reference to Figures 3 and 4. Figure 3 is an enlarged view of region Q in Figure 2. Figure 4 is a cross-sectional view taken along the arrow BB in Figure 2.

[0025] As shown in Figure 3, the runner blade 12 has a crown-side fitting portion 12a, a band-side fitting portion 12b, and a main body portion 12c.

[0026] The crown-side fitting portion 12a is a portion that can be fitted with the upper recessed fitting portion 10a formed on the lower surface of the crown 10.

[0027] The band-side fitting portion 12b is a portion that can be fitted with the fitting portion 11a, which is formed on the upper surface of the band 11 and has a recess on the lower side.

[0028] The main flow section 12c is located between the crown-side fitting section 12a and the band-side fitting section 12b, and is the part that connects the crown-side fitting section 12a and the band-side fitting section 12b. In other words, the main flow section 12c is located between the lower surface of the crown 10 and the upper surface of the band 11, and is the part of the runner vane 12 that serves as the water flow path. The inlet end 13 of the main flow section 12c has a crown-side curved section 13a, a band-side curved section 13b, and an intermediate section 13c.

[0029] The crown-side curved portion 13a is formed on the side of the inlet end 13 that is on the crown 10 side. The crown-side curved portion 13a is formed in the area of ​​the inlet end 13 that is near the lower surface of the crown 10 (near the wall surface on the crown 10 side). The area near the lower surface of the crown 10 (near the wall surface on the crown 10 side) refers to the area (boundary layer) that is greatly affected by the frictional force generated between the water flowing into the inlet end 13 and the wall surface on the crown 10 side. The crown-side curved portion 13a is formed to curve radially inward toward the crown-side connection point 13a-1, which is the connection point between the crown 10 and the inlet end 13. Specifically, the crown-side curved portion 13a is formed to curve radially inward toward the crown-side connection point 13a-1, starting from the crown-side curvature start point 13a-2, which is located in the boundary layer that is greatly affected by the frictional force generated between the water flowing into the inlet end 13 and the wall surface on the crown 10 side. In other words, the crown-side curved portion 13a is formed such that its outer diameter decreases as it moves from the crown-side curvature starting point 13a-2 towards the crown-side connection point 13a-1.

[0030] The band-side curved portion 13b is formed on the side of the inlet end 13 that is on the band 11 side. The band-side curved portion 13b is formed in the vicinity of the upper surface of the band 11 (near the wall surface on the band 11 side) within the inlet end 13. The area near the upper surface of the band 11 (near the wall surface on the band 11 side) refers to the area (boundary layer) that is greatly affected by the frictional force generated between the water flowing into the inlet end 13 and the wall surface on the band 11 side. The band-side curved portion 13b is formed to curve radially inward toward the band-side connection point 13b-1, which is the connection point between the band 11 and the inlet end 13. Specifically, the band-side curved portion 13b is formed to curve radially inward toward the band-side connection point 13b-1, starting from the band-side curvature start point 13b-2, which is located in the area that is greatly affected by the frictional force generated between the water flowing into the inlet end 13 and the wall surface on the band 11 side. In other words, the band-side curved portion 13b is formed such that its outer diameter decreases as it moves from the band-side curvature initiation point 13b-2 toward the band-side joining point 13b-1.

[0031] In this first embodiment, the crown-side coupling point 13a-1 is located radially inward from the band-side coupling point 13b-1. The crown-side curving start point 13a-2 is located radially outward from the crown-side coupling point 13a-1 and radially inward from the band-side coupling point 13b-1. Furthermore, the band-side curving start point 13b-2 is located radially outward from the band-side coupling point 13b-1.

[0032] The intermediate section 13c is the portion of the inlet end 13 located between the crown-side curved section 13a and the band-side curved section 13b. The intermediate section 13c connects the crown-side curved start point 13a-2 and the band-side curved start point 13b-2. In the first embodiment, the intermediate section 13c is formed such that its outer diameter increases as it moves from the crown-side curved start point 13a-2 to the band-side curved start point 13b-2. The line connecting the crown-side curved start point 13a-2 and the band-side curved start point 13b-2 may be a straight line or a curve.

[0033] Next, we will describe the velocity triangle when the crown-side curved portion 13a and the band-side curved portion 13b are formed.

[0034] As shown in Figure 4, the length from the rotation axis X to the crown-side curved portion 13a in the runner blade 12 of the first embodiment is smaller than the length from the rotation axis X to the inlet end 170 in the conventional runner blade 150. That is, the radius R3 of the circle traced circumferentially by the crown-side curved portion 13a of the first embodiment due to the rotation of the runner 5 during turbine operation is smaller than the radius R2 of the circle traced circumferentially by the conventional inlet end 170. Therefore, when the rotational speed of the runner 5 of the first embodiment and the rotational speed of the conventional runner 110 are both set to rotational speed N, the peripheral speed U3 (=2πR3N) of the crown-side curved portion 13a of the first embodiment is smaller than the peripheral speed U2 (=2πR2N) of the conventional inlet end 170. On the other hand, the meridian velocity Vm3 and absolute velocity V3 of the water flowing into the crown-side curved portion 13a of the first embodiment increase in inverse proportion to the decrease in radius, and are therefore larger than the meridian velocity Vm2 and absolute velocity V2 of the water flowing into the conventional inlet end 170. In this case, the directions of the peripheral velocities U3 and U2, the directions of the meridian velocities Vm3 and Vm2, and the directions of the absolute velocities V3 and V2 are approximately the same. Therefore, the relative velocity W3 of the water flowing into the crown-side curved section 13a in the first embodiment is smaller than the relative velocity W2 of the water flowing into the conventional inlet end 170. Thus, the angle β3 (relative angle β3) between the relative velocity W3 and the meridian velocity Vm3 on the velocity triangle represented by the crown-side curved section 13a in the first embodiment is smaller than the relative angle β2 on the velocity triangle represented by the conventional inlet end 170. That is, the relative angle β3 approaches the angle β0 (inlet angle β0) between the radius R3 of the runner 5 and the camber line 13d of the inlet end 13.

[0035] In Figure 4, the crown-side curved portion 13a of the inlet end 13 of the first embodiment was described, but the same applies to the band-side curved portion 13b of the inlet end 13 of the first embodiment.

[0036] As described above, in the runner blade 12 according to the first embodiment, the crown-side curved portion 13a and the band-side curved portion 13b are formed at the inlet end 13 of the runner blade 12. The outer diameters of the crown-side curved portion 13a and the band-side curved portion 13b are designed so that the relative angle β3, represented by the velocity triangle, substantially coincides with the inlet angle β0 of the inlet end 13. As a result, the discrepancy between the relative inflow angle of the water flowing into the runner 5 and the inlet angle β0 of the inlet end 13 near the wall surface can be reduced. In other words, the loss of the runner 5 can be reduced. Furthermore, it is no longer necessary to adjust the angle of the inlet end 13 in accordance with the change in the relative inflow angle of the water flowing into the runner 5 (change in relative angle), and the shape of the runner blade 12 can be easily designed.

[0037] Furthermore, in the first embodiment, the runner blade 12 is fixed by fitting the crown-side fitting portion 12a into the fitting portion 10a formed on the crown 10, and fitting the band-side fitting portion 12b into the fitting portion 11a formed on the band 11. Normally, the runner blade is joined to the crown and band by casting or welding, so a root radius R may be formed at the joint. For this reason, it may be difficult to form the crown-side curved portion 13a and the band-side curved portion 13b directly near the wall surface. However, if the runner blade 12 is inserted into the crown 10 and the band 11 and fixed, as in the first embodiment, a root radius R is not formed at the joint, so the crown-side curved portion 13a and the band-side curved portion 13b can be formed.

[0038] In the first embodiment, the runner blade 12 was described as being fixed by fitting the crown-side fitting portion 12a of the runner blade 12 into the fitting portion 10a formed on the crown 10, and fitting the band-side fitting portion 12b of the runner blade 12 into the fitting portion 11a formed on the band 11, but the embodiment is not limited to this case. For example, the runner blade 12 may be fixed to the crown 10 and the band 11 by bolts or the like. Also, for example, the runner blade 12 may be welded to the crown 10 and the band 11. Furthermore, for example, the runner 5 according to the first embodiment may be made of integrally cast steel. This is also the case in subsequent embodiments.

[0039] Furthermore, although the first embodiment described an example where both the crown-side curved portion 13a and the band-side curved portion 13b are formed at the inlet end 13 of the runner blade 12, the embodiment is not limited to this case. For example, either the crown-side curved portion 13a or the band-side curved portion 13b may be formed at the inlet end 13 of the runner blade 12. This is also true in subsequent embodiments.

[0040] Furthermore, in the first embodiment, the case where the crown-side connection point 13a-1 is located radially inward from the band-side connection point 13b-1, the crown-side curvature initiation point 13a-2 is located radially outward from the crown-side connection point 13a-1 and radially inward from the band-side connection point 13b-1, and the band-side curvature initiation point 13b-2 is located radially outward from the band-side connection point 13b-1 was illustrated as an example, but the embodiment is not limited to this case. For example, the crown-side connection point 13a-1 may be located radially inward from the band-side connection point 13b-1, the crown-side curvature initiation point 13a-2 may be located radially outward from the band-side connection point 13b-1, and the band-side curvature initiation point 13b-2 may be located radially outward from the crown-side curvature initiation point 13a-2. Furthermore, for example, the band-side connection point 13b-1 may be located radially inward from the crown-side connection point 13a-1, and the band-side curvature initiation point 13b-2 may be located radially outward from the band-side connection point 13b-1 and radially inward from the crown-side connection point 13a-1, with the crown-side curvature initiation point 13a-2 being located radially outward from the crown-side connection point 13a-1. Moreover, for example, the band-side connection point 13b-1 may be located radially inward from the crown-side connection point 13a-1, and the band-side curvature initiation point 13b-2 may be located radially outward from the crown-side connection point 13a-1, with the crown-side curvature initiation point 13a-2 being located radially outward from the band-side curvature initiation point 13b-2. Furthermore, for example, the crown-side connection point 13a-1 and the band-side connection point 13b-1 may be positioned such that they have the same diameter when centered on the axial direction X. This is also true in subsequent embodiments.

[0041] (Second Embodiment) Next, the runner blade 12 according to the second embodiment will be described using Figures 5 and 6. Figure 5 is an enlarged view of region Q in Figure 2. Figure 6 is a schematic diagram created based on the flow analysis results. Hereafter, the differences from the first embodiment will be described, and parts that are the same as in the first embodiment will be given the same figure numbers and their descriptions will be omitted.

[0042] As shown in Figure 5, the runner blade 22 has a crown-side fitting portion 12a, a band-side fitting portion 12b, and a main body portion 22c.

[0043] The main flow section 22c is located between the crown-side fitting section 12a and the band-side fitting section 12b, and is the part that connects the crown-side fitting section 12a and the band-side fitting section 12b. In other words, the main flow section 22c is located between the lower surface of the crown 10 and the upper surface of the band 11, and is the part of the runner vane 22 that serves as the water flow path. The inlet end 23 of the main flow section 22c has a crown-side curved section 23a, a band-side curved section 23b, and an intermediate section 23c.

[0044] The crown-side curved portion 23a is formed on the crown 10 side of the inlet end 23. The crown-side curved portion 23a is formed in the vicinity of the lower surface of the crown 10 (near the wall surface on the crown 10 side) of the inlet end 23. The crown-side curved portion 23a is formed to curve radially inward toward the crown-side connection point 23a-1, which is the connection point between the crown 10 and the inlet end 23. Specifically, the crown-side curved portion 23a is formed to curve radially inward toward the crown-side connection point 23a-1, starting from the crown-side curving start point 23a-2, which is located in the vicinity of the wall surface on the crown 10 side and is the point where the curving toward the crown-side connection point 23a-1 begins. In other words, the crown-side curved portion 23a is formed such that its outer diameter decreases as it moves from the crown-side curving start point 23a-2 toward the crown-side connection point 23a-1.

[0045] The band-side curved portion 23b is formed on the side of the inlet end 23 that faces the band 11. The band-side curved portion 23b is formed in the vicinity of the upper surface of the band 11 (near the wall surface on the band 11 side) within the inlet end 23. The band-side curved portion 23b is formed to curve radially inward toward the band-side connection point 23b-1, which is the connection point between the band 11 and the inlet end 23. Specifically, the band-side curved portion 23b is formed to curve radially inward toward the band-side connection point 23b-1, starting from the band-side curving start point 23b-2, which is located in the vicinity of the wall surface on the band 11 side and is the point where the curving toward the band-side connection point 23b-1 begins. In other words, the band-side curved portion 23b is formed such that its outer diameter decreases as it moves from the band-side curving start point 23b-2 toward the band-side connection point 23b-1.

[0046] In this second embodiment, the crown-side coupling point 23a-1 is located radially inward from the band-side coupling point 23b-1. The crown-side curving initiation point 23a-2 is located radially outward from the crown-side coupling point 23a-1 and radially inward from the band-side coupling point 23b-1. Furthermore, the band-side curving initiation point 23b-2 is located radially outward from the band-side coupling point 23b-1.

[0047] The intermediate section 23c is the portion of the inlet end 23 located between the crown-side curved section 23a and the band-side curved section 23b. The intermediate section 23c connects the crown-side curve initiation point 23a-2 and the band-side curve initiation point 23b-2. In the second embodiment, the intermediate section 23c is formed such that its outer diameter increases as it moves from the crown-side curve initiation point 23a-2 to the band-side curve initiation point 23b-2. The line connecting the crown-side curve initiation point 23a-2 and the band-side curve initiation point 23b-2 may be a straight line or a curve.

[0048] Next, the range in which the crown-side curved portion 23a and the band-side curved portion 23b are formed will be described.

[0049] Figure 5 shows the flow path height 33, which is the height between the crown-side connection point 23a-1 and the band-side connection point 23b-1 (the height between the lower surface of the crown 10 and the upper surface of the band 11), the range 33a in which the crown-side curved portion 23a is formed relative to the flow path height 33, and the range 33b in which the band-side curved portion 23b is formed relative to the flow path height 33. Figure 6 shows a schematic diagram created based on the flow analysis results, where the vertical axis is the relative position value with respect to the flow path height 33, with the upper surface of the band 11 being 0.0 and the lower surface of the crown 10 being 1.0, and the horizontal axis is the relative inflow angle (relative angle β) of the water flowing into the runner 5.

[0050] As shown in Figure 6, near the wall surface on the crown 10 side, the relative inflow angle (relative angle β) of the water flowing into the runner 5 tends to change due to the effect of friction with the wall surface. In particular, the relative angle β tends to be larger in the range of 0.92 to 1.0 of the flow path height 33. Therefore, the crown-side curved section 23a is formed in the range of 0.92 to 1.0 of the flow path height 33 (range 33a) to adjust for this deviation in relative angle β. That is, the crown-side curved section 23a is formed in a range where the height is within 8% of the height from the crown-side connection point 23a-1 (within 8% of the height from the bottom surface of the crown 10) relative to the flow path height 33. Specifically, the crown-side curved starting point 23a-2 is located in a range where the height is within 8% of the height from the crown-side connection point 23a-1 (within 8% of the height from the bottom surface of the crown 10) relative to the flow path height 33. Furthermore, the crown-side curved portion 23a is formed to curve radially inward from the crown-side curving start point 23a-2 toward the crown-side joining point 23a-1, within a range where the height is within 8%. In this way, it is preferable that the crown-side curved portion 23a is formed in a range where the relative angle β changes near the lower surface of the crown 10.

[0051] Furthermore, as shown in Figure 6, near the wall surface on the band 11 side, the relative inflow angle (relative angle β) of the water flowing into the runner 5 tends to change due to the effect of friction with the wall surface. In particular, the relative angle β tends to be larger in the range of 0.0 to 0.08 of the flow path height 33. Therefore, the band-side curved section 23b is formed in the range of 0.0 to 0.08 of the flow path height 33 (range 33b) to adjust for this deviation in relative angle β. That is, the band-side curved section 23b is formed in a range where the height is within 8% of the band-side connection point 23b-1 relative to the flow path height 33 (within 8% of the height from the top surface of the band 11). Specifically, the band-side curved start point 23b-2 is located in a range where the height is within 8% of the band-side connection point 23b-1 relative to the flow path height 33 (within 8% of the height from the top surface of the band 11). Furthermore, the band-side curved portion 23b is formed to curve radially inward from the band-side curving start point 23b-2 toward the band-side joining point 23b-1, within a range where its height is within 8%. In this way, it is preferable that the band-side curved portion 23b is formed in a range where the relative angle β changes near the upper surface of the band 11.

[0052] In the runner vane 22 according to the second embodiment, the crown-side curved portion 23a is formed in a range of 8% from the lower surface of the crown 10 relative to the flow path height 33, and the band-side curved portion 23b is formed in a range of 8% from the upper surface of the band 11 relative to the flow path height 33. As a result, it exhibits the same effects as the first embodiment, and can more effectively adjust the discrepancy that occurs near the wall surface between the relative inflow angle (relative angle β) of the water flowing into the runner 5 and the inflow angle β0 of the inlet end 13. In other words, it can more effectively reduce the loss of the runner 5.

[0053] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, modifications, and combinations are possible without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as described in the claims. [Explanation of Symbols]

[0054] 1...Francis turbine, 2...Casing, 3...Stay vanes, 4...Guide vanes, 5...Runner, 6...Main shaft, 7...Generator, 8...Draw-out tube, 10...Crown, 10a...Matching section, 11...Band, 11a...Matching section, 12...Runner blades, 12a...Crown side fitting section, 12b...Band side fitting section, 12c...Main flow section, 13...Inlet end, 13a...Crown side curved section, 13a-1...Crown side connection point, 13a-2...Crown side curved start point, 13b...Band side curved section, 13 b-1...band side connection point, 13b-2...band side curving start point, 13c...intermediate section, 13d...camber line, 14...outlet end, 22...runner vane, 22a...crown side fitting section, 22b...band side fitting section, 22c...main stream section, 23...inlet end, 23a...crown side curved section, 23a-1...crown side connection point, 23a-2...crown side curving start point, 23b...band side curved section, 23b-1...band side connection point, 23b-2...band side curving start point, 33...flow path height.

Claims

1. The inlet end of the runner vane provided between the crown and the band is formed on the crown side and has a crown-side curved portion that curves radially inward toward the crown-side connection point, which is the connection point between the inlet end and the crown, Of the aforementioned inlet end, a band-side curved portion is formed on the band side and curves radially inward toward the band-side connection point, which is the connection point between the band and the inlet end, A runner for a hydraulic machine, characterized in that at least one of the following is formed.

2. At least the crown-side curved portion is formed at the inlet end, The runner for a hydraulic machine according to claim 1, characterized in that the crown-side curved portion is formed to curve radially inward from a crown-side curving start point located in an area that is greatly affected by the frictional force generated between the water flowing into the inlet end and the wall surface on the crown side toward the crown-side joint point.

3. At least the crown-side curved portion is formed at the inlet end, The runner for a hydraulic machine according to claim 1, characterized in that the crown-side curved portion is formed to curve radially inward toward the crown-side connection point, starting from a crown-side curvature initiation point located within a range of 8% of the height from the crown-side connection point with respect to the flow path height which is the height between the crown-side connection point and the band-side connection point.

4. At least the band-side curved portion is formed at the inlet end, The runner for a hydraulic machine according to claim 1, characterized in that the band-side curved portion is formed to curve radially inward from a band-side curving start point located in an area that is greatly affected by the frictional force generated between the water flowing into the inlet end and the wall surface on the band side, toward the band-side coupling point.

5. At least the band-side curved portion is formed at the inlet end, The runner for a hydraulic machine according to claim 1, characterized in that the band-side curved portion is formed to curve radially inward toward the band-side connection point, starting from a band-side curvature initiation point located within a range of 8% of the height from the band-side connection point with respect to the flow path height which is the height between the crown-side connection point and the band-side connection point.

6. The runner for a hydraulic machine according to any one of claims 1 to 5, characterized in that the crown-side coupling point is located radially inward from the band-side coupling point.

7. The crown-side joint point is located radially inward from the band-side joint point. The runner for a hydraulic machine according to claim 2 or 3, characterized in that the crown-side curvature initiation point is located radially outward from the crown-side connection point and radially inward from the band-side connection point.

8. The band-side bonding point is located radially outward from the crown-side bonding point. The runner for a hydraulic machine according to claim 4 or 5, characterized in that the band-side curvature initiation point is located radially outward from the band-side coupling point.

9. The aforementioned runner blades are, The crown has a fitting portion formed on it and a crown-side fitting portion that can be fitted into it. A fitting portion formed on the band and a fitting portion on the band side that can be fitted, The main body portion located between the crown-side fitting portion and the band-side fitting portion, Equipped with, A runner for a hydraulic machine according to any one of claims 1 to 5, characterized in that at least one of the crown-side curved portion and the band-side curved portion is formed at the inlet end of the main flow portion.

10. A hydraulic machine characterized by comprising a runner for a hydraulic machine according to any one of claims 1 to 5.

Images