JP2010090844A - Waterwheel runner and waterwheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waterwheel runner and waterwheel which suppresses increase in the rate of a local flow at a corner formed between the blade of a runner vane and the stem to reduce a friction loss occurring with the increase in the flow rate, and thereby improving hydraulic power efficiency. <P>SOLUTION: The waterwheel runner 12 having: a runner boss 18 rotatably mounted around a runner rotation shaft 17 and provided with a runner boss side running water surface 19 formed by a part of a spherical surface with the center O and the radius Ro; and a plurality of runner vanes 20 disposed radially to the circumference of the runner boss and mounted with adjustable mounting angles, wherein the runner vane comprise a blade 21 and a stem 22 supporting the blade to the runner boss, a stem side running water surface 24 continuing to a runner boss side running water surface 19 is formed on the stem, and when an arbitrary point on the stem side running water surface is designated as P, the point P exists which satisfies the relational expression of Ro>OP between the length of the line segment OP connecting the center O and the point P and the radius Ro. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a runner vane movable turbine wheel runner in which a runner vane mounting angle can be adjusted, and a turbine equipped with the turbine runner.

  A Kaplan turbine, which is a type of axial flow turbine, has a runner vane movable turbine runner in which the runner vane mounting angle can be adjusted. The structure of the water turbine runner will be described with reference to a schematic configuration diagram shown in FIG. The water turbine runner 90 of the Kaplan water turbine is configured such that the mounting angle of the runner vane 91 can be adjusted with respect to the runner boss 93. The water surface formed by the stem 92 and the runner boss 93 that are the support portions of the runner vane 91 has a center Q and a radius S so that the flow path is smoothly connected even if the runner vane 91 rotates about the runner vane rotation shaft 94. The runner vane rotating shaft 94 is set so as to have the same spherical surface and pass through the center Q of the spherical surface. For this reason, even if the runner vane 91 is rotated around the runner vane rotation shaft 94 and the mounting angle thereof is adjusted, the water surfaces of the runner boss 93 and the stem 92 are always present on the same spherical surface. Does not disturb the flow of water.

  In the conventional runner vane movable turbine runner 90 designed as described above, a corner portion 96 (FIG. 10) is formed by the runner boss 93 and the vane 95 of the runner vane 91, and the stem 92 of the runner vane 91 and the vane 95 of the runner vane 91 are formed. As a result, a corner 97 (FIG. 10) is formed. Among these corner portions, the corner portion 97 of the stem 92 and the blade 95 of the runner vane 91 has a smooth curved fillet 98 between the water surface of the stem 92 and the surface of the blade 95 in order to avoid stress concentration. (FIG. 8) is formed.

As described above, Patent Document 1 describes the runner vane movable turbine runner 90 in which the mounting angle of the runner vane 91 can be adjusted. In addition, the code | symbol 99 in FIG. 8 shows the rotating shaft (runner rotating shaft) which the water turbine runner 90 rotates.
JP-A-1-203661

  As shown in FIG. 9, the fluid flowing from the upstream along the spherical runner boss 93 is bent and accelerated by the convex curved surface of the runner boss 93. As shown in FIG. 10, around the corner portions 96 and 97 formed by the blades 95 of the runner vanes 91, the runner bosses 93, and the stems 92, fluid flowing along the surfaces of the blades 95 is directed to the corner portions 96 and 97. Since the air may flow, local flow speed increases at the corners 96 and 97 become more prominent. As a result, the friction loss increases at the corner portions 96 and 97, particularly the corner portion 97 between the blade 95 and the stem 92, and the hydraulic efficiency of the water turbine runner 90 decreases.

  The object of the present invention has been made in consideration of the above-mentioned circumstances, and this flow velocity is suppressed by suppressing local flow acceleration at the corner portion formed between the runner vane blade and the stem. It is an object of the present invention to provide a turbine runner and a turbine that can reduce friction loss caused by an increase in the hydraulic power, and as a result, can improve hydraulic efficiency.

A water turbine runner according to the present invention is provided so as to be rotatable about a runner rotation axis, and includes a runner boss having a runner boss side water surface formed by a part of a spherical surface having a center O and a radius Ro, and a radial direction in the circumferential direction of the runner boss. A runner vane having a plurality of runner vanes provided with adjustable mounting angles, the runner vane comprising blades and a stem for supporting the blades on the runner boss, the stem Is formed with a stem-side water surface continuous with the runner boss-side water surface, and when an arbitrary point on the stem-side water surface is P, the length of the line segment OP connecting the center O and the point P is And the radius Ro,
[Equation 1]
Ro> OP
The point P that satisfies the above condition exists.

  Moreover, the water wheel according to the present invention includes the water wheel runner according to the present invention.

  According to the turbine runner and the turbine according to the present invention, the stem-side flow surface is set on the inner side of the runner-boss side flow surface (the center side of the runner-boss-side flow surface), and thus formed between the runner vane blades and the stem. The cross-sectional area of the corner portion can be enlarged. For this reason, local increase in flow rate at the corner portion can be suppressed, and friction loss generated as the flow rate increases can be reduced. As a result, hydraulic efficiency can be improved.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the present invention is not limited to these embodiments.

[A] First embodiment (FIGS. 1 to 3)
FIG. 1 is a configuration diagram schematically showing a part of a Kaplan water turbine to which a first embodiment of a water turbine runner according to the present invention is applied, along a meridian plane. FIG. 2 is a configuration diagram schematically showing a part of the water turbine runner of FIG. 1 along a plane including a runner vane rotation axis.

  As shown in FIG. 1, a Kaplan turbine 10 that is a kind of axial flow turbine is provided with a turbine runner 12 that is a rotating portion at a central position of a casing 11 that is a stationary portion that constitutes a flow path. A stay vane 13 and a flow rate adjusting guide vane 14 are sequentially arranged on the upstream side of the path, and a suction pipe 15 is connected to the downstream side.

  A plurality of turbine runners 12 are radially arranged in a circumferential direction on a runner boss 18 attached to a main shaft 16 and rotatably provided around a runner rotation shaft 17 and a runner boss side flowing water surface 19 which is an outer peripheral surface of the runner boss 18. And a runner vane 20 provided.

  As shown in FIG. 2, the runner boss side flowing water surface 19 is formed as a part of a spherical surface having a radius Ro at the center O. The fluid flowing in the casing 11 flows along the runner boss side flowing water surface 19. The main shaft 16 coupled to the runner boss 18 is coupled to a generator (not shown).

  The runner vane 20 includes a blade 21 and a stem 22 that supports the blade 21 on the runner boss 18. The runner vane 20 is configured to be rotatable about the runner vane rotation shaft 23 with respect to the runner boss 18. Adjustable. In the runner boss 18, a link mechanism (not shown) for rotating the runner vane 20 about the runner vane rotating shaft 23 is accommodated.

  In such a Kaplan turbine 10, as shown in FIG. 1, the fluid (water) from the upper pond passes through the flow path of the casing 11 and is accelerated by the stay vane 13, and the flow rate is adjusted through the guide vane 14. After reaching the runner vane 20 of the runner 12 and rotating the turbine runner 12 around the runner rotating shaft 17, the runner 12 flows out into the lower pond via the suction pipe 15. The rotational energy of the water turbine runner 12 is transmitted to the generator via the main shaft 16 and converted into electric energy.

  In this water wheel runner 12, since the mounting angle of the runner vane 20 is provided so as to be adjustable, the mounting angle of the runner vane 20 is adjusted and optimized with respect to the drop between the upper pond and the lower pond and the fluctuation of the fluid flow rate. It is possible to obtain highly efficient power generation characteristics over a wide operating range.

  As shown in FIGS. 2 and 3, the stem 22 of the runner vane 20 is formed with a stem-side flow surface 24 continuous with the runner boss-side flow surface 19. The fluid that has flowed along the runner boss side flow surface 19 continuously flows smoothly along the stem side flow surface 24. In FIG. 2, a part of the runner boss side water surface 19 is indicated by an imaginary line α (two-dot chain line).

  As described above, in the runner vane movable turbine wheel runner 12 in which the mounting angle of the runner vane 20 can be adjusted, the runner vane rotation shaft 23 passes through the center O of the spherical surface forming the runner boss side flowing water surface 19, and the runner vane rotation shaft 23 is the center. The stem 20 is formed in a disc shape so that the runner vane 20 can rotate. For this reason, as shown in FIG. 3, the shape of the boundary between the stem-side flow surface 24 and the runner boss-side flow surface 19 is a circle C, and the center A of this circle C is positioned on the runner vane rotating shaft 23.

  Further, a corner portion 25 is formed between the runner boss 18 and the vane 21 of the runner vane 20, and further, a corner portion 26 continuous with the corner portion 25 is formed between the stem 22 of the runner vane 20 and the vane 21. Among these, the corner portion 26 between the stem 24 and the blade 21 has a smooth curved surface with an appropriate radius between the stem-side water surface 24 of the stem 22 and the blade surface of the blade 21 in order to avoid stress concentration. Fret 27 (FIG. 2) is formed.

Further, in the runner vane 20, when an arbitrary point on the stem-side flow surface 24 is P, the length of the line segment OP connecting the center O of the spherical surface of the runner-boss flow surface 19 and the point P, and the runner-boss flow surface Between 19 spherical radii Ro,
[Equation 2]
Ro> OP
The stem side flowing water surface 24 of the stem 22 is formed such that there is a point P that satisfies the above. That is, the stem-side water surface 24 is set closer to the center O side of the runner boss side water surface 19 than the runner boss side water surface 19.

  Therefore, according to the present embodiment, the following effect (1) is obtained.

  (1) Between the length of a line segment OP connecting an arbitrary point P on the stem side water surface 24 and the center O of the spherical surface of the runner boss side water surface 19, and the radius Ro of the spherical surface of the runner boss side water surface 19; The stem side water surface 24 is formed so that there is a point P that satisfies Ro> OP, and the stem side water surface 24 is set closer to the center O side of the runner boss side water surface 19 than the runner boss side water surface 19. ing. Therefore, the flow path cross-sectional area of the corner portion 26 formed between the stem 22 of the runner vane 20 and the blades 21 can be enlarged as compared with the conventional water turbine runner 90 (FIG. 8). The local flow speed increase can be suppressed, and the friction loss generated with the increase in the flow velocity can be reduced. As a result, the hydraulic efficiency of the Kaplan turbine 10 can be improved.

[B] Second embodiment (FIG. 4)
FIG. 4 is a configuration diagram schematically showing a part of the second embodiment of the water turbine runner according to the present invention along a plane including the runner vane rotating shaft. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The difference between the turbine runner 31 of the Kaplan turbine 30 of the present embodiment and the first embodiment is the shape of the stem-side flow surface 34 of the stem 33 in the runner vane 32.

  That is, the stem side water surface 34 includes this circle C and is parallel to the runner rotating shaft 17 and orthogonal to the runner vane rotating shaft 23 when a circle formed at the boundary with the runner boss side water surface 19 is C. Formed by a flat surface. Thereby, the flow path cross-sectional area of the corner part 26 formed by the blade 21 of the runner vane 32 and the stem 33 of the runner vane 32 is enlarged.

  Therefore, according to the present embodiment, in addition to the same effect as the effect (1) of the first embodiment, the following effect (2) is achieved.

  (2) Since the stem side flow surface 34 of the stem 33 in the runner vane 32 is formed in a plane including the circle C at the boundary with the runner boss side flow surface 19, in the corner portion 26 between the blade 21 and the stem 33 in the runner vane 32. Enlarging the channel cross-sectional area can be realized by a simple method.

[C] Third embodiment (FIGS. 5 and 6)
FIG. 5 is a configuration diagram schematically showing a part of the third embodiment of the water turbine runner according to the present invention along a plane including the runner vane rotating shaft. In the third embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The difference between the turbine runner 41 of the Kaplan turbine 40 of the present embodiment and the first embodiment is that the runner vane 42 is set on the stem-side flow surface 44 of the stem 43 in the runner vane 42. An arbitrary point P is set only on the suction surface side of the runner vane 42.

  Usually, a phenomenon called cavitation often occurs in a passage of a water turbine at a location where the pressure drops and reaches a saturation vapor pressure or less. This cavitation causes various problems, such as vibration, noise, reduced turbine efficiency, and erosion, and the range of operation of the turbine is limited due to vibration, and the runner vane is damaged by erosion and the update interval is shortened. It is also the cause of serious situations.

  Here, as shown in FIG. 6, in a general Kaplan turbine 100, the suction surface of the runner vane 102 to the runner vane 103 in the rotating field of the runner vane movable turbine runner 101 that can adjust the mounting angle of the runner vane 103 with respect to the runner boss 102. When the fluid flows to the bottom, the pressure locally decreases on the suction surface side of the runner vane 103, and cavitation may occur.

  In particular, on the suction surface side of the runner vane 103, the corner portion 106 formed between the vane 104 of the runner vane 103 and the runner boss 102, and between the vane 104 of the runner vane 103 and the stem 105, the corner portion 106 is formed. Cavitation is likely to occur in the corner portion 107 that is continuous to the corner portion 107, particularly in the peripheral portion of the corner portion 107. This is because the upstream flow of the water turbine runner 101 flows along the curved surface of the runner boss 102 and the increased speed operation due to the flow along the blades 104 of the runner vanes 103 flowing into the corner portions 106 and 107. This is presumed to be due to the synergistic effect of the speed increasing action due to the low pressure on the suction surface side of the vane 104 of the runner vane 103 and a significant pressure drop locally.

In the turbine runner 41 of the Kaplan turbine 40 of the present embodiment shown in FIG. 5, an arbitrary point P set on the stem-side flow surface 44 of the stem 43 and the runner boss 18 in the runner boss 18 only on the negative pressure surface side of the runner vane 42. The line segment OP connecting the spherical surface center O of the side water surface 19 is between the radius Ro of the spherical surface of the runner boss side water surface 19 [Equation 3]
Ro> OP
Meet. That is, only the negative pressure surface side of the runner vane 42 on the stem side flow surface 44 is set to be closer to the center O side of the runner boss side flow surface 19 than the runner boss side flow surface 19.

  Therefore, according to the present embodiment, the following effects (3) and (4) are achieved.

  (3) Since the stem side water surface 44 is set closer to the center O side of the runner boss side water surface 19 than the runner boss side water surface 19 on the negative pressure surface side of the runner vane 42, the runner vane 42 on the negative pressure surface side of the runner vane 42. The channel cross-sectional area of the corner portion 26 formed by the 42 blades 21 and the stem 43 can be enlarged. For this reason, the local flow speed increase in the corner portion 26 can be suppressed, and the friction loss caused by the increase in the flow velocity can be reduced. As a result, the hydraulic efficiency of the Kaplan turbine 40 can be improved.

  (4) On the suction surface side of the runner vane 42, the flow path cross-sectional area of the corner portion 26 formed by the vane 21 and the stem 43 of the runner vane 42 is enlarged, and the local flow acceleration at the corner portion 26 is increased. Therefore, it is possible to reduce the pressure drop caused by the increase in the flow velocity. Thereby, generation | occurrence | production of the cavitation in the suction surface side of the runner vane 42 can be suppressed.

[D] Fourth embodiment (FIG. 7)
FIG. 7 is a configuration diagram schematically showing a part of the fourth embodiment of the water turbine runner according to the present invention along a plane including the runner vane rotating shaft. In the fourth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The turbine runner 51 of the Kaplan turbine 50 according to the present embodiment is different from the first embodiment in that an arbitrary point P on the stem-side flow surface 54 of the stem 53 is only on the negative pressure surface side of the runner vane 52. Similar to the third embodiment, Ro> OP is satisfied, and the fillet 55 on the pressure surface side and the fillet 56 on the suction surface side of the runner vane 52 are set in a predetermined shape.

That is, only on the suction surface side of the runner vane 52, a line segment OP connecting an arbitrary point P set on the stem-side water surface 54 and the center O of the spherical surface of the runner boss-side water surface 19 is formed on the runner boss-side water surface 19. Between the radius Ro of the sphere [Formula 4]
Ro> OP
Meet. In other words, only the negative pressure surface side of the runner vane 52 on the stem side flow surface 54 is set to be closer to the center O side of the runner boss side flow surface 19 than the runner boss side flow surface 19.

Further, on the pressure surface side of the runner vane 52, the radius Rp of the fillet 55 formed at the corner portion 26 between the blade 21 and the stem-side flow surface 54, and on the negative pressure surface side of the runner vane 52, the blade 21 and the stem-side flow water. The radius Rs of the fillet 56 formed in the corner portion 26 between the surface 54 and
[Equation 5]
Rp> Rs
It is configured to satisfy.

  At this time, the radius Rs of the fillet 56 is such that stress concentration does not occur between the blade 21 and the stem flow surface 54 on the suction surface side of the runner vane 52, and the stem 53 has a minimum thickness that does not hinder the strength. Is set as follows. Then, by setting the radius Rp of the fillet 55 on the pressure surface side of the runner vane 52 to be larger than the radius Rs of the fillet 56 on the suction surface side of the runner vane 52, the thickness on the suction surface side of the runner vane 52 in the stem 53 is set. The reduced thickness can be compensated by securing the thickness of the runner vane 52 on the pressure surface side.

  Therefore, according to the present embodiment, in addition to the same effects as the effects (3) and (4) of the third embodiment, the following effect (5) is achieved.

  (5) Since the radius Rp of the fillet 55 on the pressure surface side of the runner vane 52 is set larger than the radius Rs of the fillet 56 on the suction surface side of the runner vane 52 (Rp> Rs), the pressure of the runner vane 52 in the stem 53 Since the thickness on the surface side can be sufficiently maintained, the strength of the stem 53 can be sufficiently ensured.

The block diagram which shows typically a part of Kaplan water turbine to which 1st Embodiment of the water turbine runner concerning this invention was applied along a meridian surface. The block diagram which shows typically a part of watermill runner of FIG. 1 along the surface containing a runner vane rotating shaft. FIG. 3 is an III arrow view of the water wheel runner of FIG. 2 viewed from the runner vane rotation axis direction. The block diagram which shows typically a part of 2nd Embodiment of the water turbine runner which concerns on this invention along the surface containing a runner vane rotating shaft. The block diagram which shows typically a part of 3rd Embodiment of the water turbine runner which concerns on this invention along the surface containing a runner vane rotating shaft. Explanatory drawing explaining the cavitation which generate | occur | produces in the corner part formed with the blade | wing of a runner vane, a stem, and a runner boss | hub on the negative pressure surface of a runner vane. The block diagram which shows typically a part of 4th Embodiment of the turbine runner which concerns on this invention along the surface containing a runner vane rotating shaft. The block diagram which shows typically a part of turbine runner of the conventional Kaplan water turbine along the surface containing a runner vane rotating shaft. In the waterwheel runner of FIG. 8, explanatory drawing explaining the flow along a runner boss. FIG. 9 is an explanatory diagram for explaining the flow around the stem of the runner vane in the water turbine runner of FIG. 8.

Explanation of symbols

10 Kaplan turbine 12 Turbine runner 17 Runner rotation shaft 18 Runner boss 19 Runner boss side flow surface 20 Runner vane 21 Blade 22 Stem 24 Stem side flow surface 30 Kaplan turbine 31 Turbine runner 32 Runner vane 33 Stem 34 Stem side flow surface 40 Kaplan turbine 41 Water turbine runner 42 Runner vane 43 Stem 44 Stem side flow surface 50 Kaplan water wheel 51 Turbine runner 52 Runner vane 53 Stem 54 Stem side flow surface 55, 56 Fillet C Circle O Center P Point OP Line segment Ro, Rp, Rs Radius

Claims (5)

A runner boss provided with a runner boss side flowing water surface which is provided so as to be rotatable around the runner rotation axis and is formed of a part of a spherical surface having a center O and a radius Ro;
A runner vane that is radially arranged in the circumferential direction of the runner boss and has a runner vane that is provided so that the mounting angle can be adjusted.
The runner vane includes a blade and a stem that supports the blade on the runner boss,
The stem has a stem-side water surface that is continuous with the runner boss-side water surface, and when an arbitrary point on the stem-side water surface is P, a line segment OP connecting the center O and the point P And the radius Ro,
[Equation 1]
Ro> OP
A turbine runner characterized in that the point P satisfying The stem-side flow surface is formed by a plane including the circle C and parallel to the runner rotation axis, where C is a circle formed at the boundary with the runner boss-side flow surface. 1. The water wheel runner according to 1. The turbine runner according to claim 1, wherein an arbitrary point P on the stem-side flow surface is set on the suction surface side of the runner vane. A fillet radius Rp formed between the vane and the stem flow surface on the pressure surface side of the runner vane, and a fillet radius Rs formed between the blade and the stem flow surface on the suction surface side of the runner vane. And
[Equation 2]
Rp> Rs
The water turbine runner according to claim 3, wherein: A water wheel comprising the water wheel runner according to any one of claims 1 to 4.

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