JP2003314425A - Pump turbine with splitter runner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pump turbine having a splitter runner wherein a low lift operating range is expanded to increase a pump efficiency by effectively suppressing a cavitation occurring on a runner vane during a low lift operation. <P>SOLUTION: This pump turbine having the splitter runner is formed so that the edge lines of short vanes 18 and a band 21 on the connection point side among the edge lines LE of the short vanes 18 in height direction at the front edge 19 during the operation of the pump are positioned in a direction reverse to the rotating direction of the runner during the operation of the pump on the basis of the connection point J<SB>1</SB>of a radial radiating line RL<SB>1</SB>radially extending from the center line of a spindle in radial direction through the connection point J<SB>1</SB>between the short vanes 18 and a crown 20 with the short vanes 18 and the crown 20. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump turbine having a splitter runner in which long blades and short blades are alternately arranged along a circumferential direction, and in particular, a short blade pump. The present invention relates to a pump-turbine provided with a splitter runner for improving the shape of an inlet-side edge during operation. 2. Description of the Related Art Generally, a pump-turbine can be freely switched between a power generation operation and a pump operation by changing the rotation direction of a runner. [0003] During power generation operation, a pump turbine guides running water flowing into a spiral casing to a runner through a guide vane, where the runner is driven to rotate, and the rotational torque generated at that time is passed through a main shaft. The power is given to the generator. Further, during the operation of the pump, the pump-turbine rotates the runner by the driving force of the generator motor in a direction opposite to the power generation operation, and guides the flowing water of the suction pipe to the runner chamber, where the water flows from the runner to the flowing water. Energized, upper pond (not shown) through guide vanes and spiral casing
It is designed to be pumped. As described above, the runner of the pump turbine capable of freely switching between the power generation operation and the pump operation is provided with a plurality of runner vanes arranged at a constant pitch along the circumferential direction. Are supported between the crown provided on the main shaft (rotating shaft) side and the band provided on the suction pipe side. As shown in FIG. 6, a pump-turbine having a runner having such a structure is provided with six runner vanes 7 of the same length fixed to a crown 8 along the circumferential direction of the runner 3.
It is common to install two sheets (Japanese Patent Laid-Open No. 2000-1367).
66 gazette), and the use results thereof are increasing. However, in recent pump-turbines, high-efficiency operation is enabled even when the head or flow rate changes during the operation of the turbine, or the water is generated at the inlet side of the runner vane 7 during the operation of the turbine or the pump. For the purpose of suppressing cavitation, for example, as shown in FIGS. 7 and 8,
A so-called splitter runner in which the runner vane 7 of the short wing 11 is arranged between the runner vane 7 of the long wing 10 fixed to the crown 8 and the runner vane 7 of the adjacent long wing 10 has been proposed (Japanese Patent Application Laid-Open No. 2001-90650). ). FIG. 8 is a projection diagram of such a splitter runner projected on a plane perpendicular to the rotation axis and viewed from the side of the suction pipe. The solid line is the runner vane 7 of the long blade 10, and the broken line is the broken line. Is the runner vane 7 of the short wing 11. As shown in FIG. 8, in such a splitter runner, the projection of the long wing 10 and the end of the crown 8 from the center point O of the main axis, which is the axis of rotation, in a projection onto a plane perpendicular to the axis of rotation. radial radiation RL through the connection point P ₁ parts
₁ and the leading edge (long edge pump inlet edge curve) 12 of the long blade 10 during pump operation often coincide with each other, and the center point O of the main shaft, the connection between the long blade 10 and the end of the crown 8 The point P ₁ and the connection point Q ₁ between the long wing 10 and the end of the band 9 are configured to be arranged on the radial radiation RL ₁ . The same applies to the short wing 11, and the connection point P between the short wing 11 and the end of the crown 8 from the center point O of the main axis, which is the rotation axis, on the projection onto a plane perpendicular to the rotation axis. radial radiation RL ₂ through _2, it is often the leading edge (short blade pump inlet edge curve) 13 short blades 11 of pump operation are the same, the center point of the main shaft O, and short blade 11 The connection point P ₂ between the end of the crown 8 and the connection point Q ₂ between the short wing 11 and the end of the band 9 are arranged on the radial radiation RL ₂ . In the splitter runner, the long wing 10,
By alternately providing 4 to 6 short blades 11 each, the number of runner vanes 7 is increased as compared with a normal pump-turbine to reduce the blade load per runner vane 7 and, particularly, on the inlet side during pump operation. In this case, the flow path between the runner vanes 7 can be prevented from becoming extremely narrow. However, if the length of the short wing 11 is too short, the blade load of the short wing is reduced during operation of the water turbine and does not effectively act as the runner vane 7, or the cavitation characteristics on the inlet side of the short wing deteriorate. Therefore, the length of the short blades 11 is increased within a range that does not interfere with the inlet port formed between the adjacent long blades 10 on the inlet side during pump operation (ie, the outlet side during turbine operation). Preferably
It is often 70% to 80% of the long wing 11. FIG.
FIG. 3 is a schematic development view of the arrangement of the runner vanes 7 on the band side of the conventional splitter runner as viewed from the outside. As shown in FIG. Is located downstream from the virtual leading edge line ILE connecting the leading edge 12 of the adjacent long wing 10 and the leading edge 12 of the adjacent long wing 10 during the pump operation. As described above, the pump turbine having the splitter type runners 3 in which the long blades 10 and the short blades 11 are alternately arranged along the circumferential direction of the runner 3 reduces the blade load per runner vane. In recent years, it has the advantage of improving the rectification effect of flowing water, suppressing the pressure drop on the blade negative pressure surface, and increasing the efficiency of converting the energy of flowing water into power (rotary torque) and suppressing cavitation. R & D is being promoted. As shown in FIG. 9, in a pump-turbine provided with a splitter type runner 3, when the pump is operated, the flowing water flows with respect to the long blades 10 at a relative speed W at the time of design.
When flowing in with a vector of ₀ (broken line), cavitation is not generated because there is little discrepancy between the inlet installation angle of the long blade 10 and the flowing water inflow angle. However, when the operation state changes and the pump turbine operates at a low head, the pumping amount increases, so that flowing water flows into the pump turbine at a vector (solid line) of the relative speed W ₀ to the long blade 10. Become like Therefore, the cavitation CA is formed around the leading edge 12 of the pressure surface 14 of the long wing 10.
V tends to occur, but this tendency is particularly remarkable on the band 9 side. Such cavitation CAV generated on the pressure surface on the band 9 side at the inlet of the runner vane 7 at the time of pump operation at a low head is caused by a pump turbine having only the long blade 10,
This occurs regardless of the pump turbine provided with the splitter runner, but in the pump turbine provided with the splitter runner, FIG.
As shown in (1), since the flow path width FW between the runner vane 7 of the long wing 10 and the runner vane of the adjacent short wing 11 is narrow, the flow path in this portion is easily blocked by the occurrence of cavitation CAV. For this reason, in the pump turbine provided with the conventional splitter runner, the pump efficiency is significantly reduced during such a low head operation, and as a result, there is a problem that the operating range of the pump operation on the low head side is narrowed. . The present invention has been made in view of such circumstances, and more effectively suppresses cavitation generated in the runner vanes during low-head operation, and as a result, further widens the low-head operation width. An object of the present invention is to provide a pump-turbine provided with a splitter-type runner for improving pump efficiency. According to a first aspect of the present invention, there is provided a pump-turbine provided with a splitter-type runner according to the present invention. In a pump-turbine provided with a splitter runner that supports and alternately arranges long blades and short blades along the circumferential direction of the runner, an edge line at a leading edge of the short blade during a pump operation includes the edge line and the band. The connection point side of the splitter runner is formed so as to be located in the direction opposite to the rotation direction of the splitter runner during pump operation with reference to a straight line passing from the rotation center of the splitter runner to the connection point between the edge line and the crown. Is what is done. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a pump-turbine equipped with a splitter runner according to the present invention will be described with reference to the drawings and reference numerals attached to the drawings. FIG. 1 is a view showing a first embodiment of a pump-turbine provided with a splitter runner according to the present invention. FIG. 1 shows a plane perpendicular to the center line of the main shaft (rotation axis),
It is a runner projection diagram projected when it sees from a draft tube side. The pump-turbine provided with the splitter runner according to the present embodiment includes a crown 20 and a band 21 and a runner 15 including a plurality of runner vanes 16 supported between the crown 20 and the band 21 and arranged along the circumferential direction. It is configured. The runner vanes 16 include long blades 17 indicated by solid lines and short blades 18 indicated by broken lines. The long blades 17 and the short blades 18 are alternately arranged along the circumferential direction of the runner 15. The short wings 18 of the long wings 17 and the short wings 18 alternately arranged in this manner form an edge line LE of a leading edge (short wing pump inlet edge) 19 on the inlet side of the water flow during the pump operation. From the crown 20 to the band 21, it is formed so as to face in the opposite direction (counterclockwise) to the rotation direction RV of the runner 15 during the pump operation with respect to the radiation direction from the center point O of the main shaft (rotation axis). . That is, in the present embodiment, the edge line LE of the leading edge (short blade pump inlet edge) 19 during the pump operation of the short blade 18 is defined by the connection point K ₁ between the edge line LE and the band 21. through the connection point J ₁ of the short blade 18 and the crown 20 from the center point O of the (rotary shaft), so as to be positioned in the runner rotating direction RV opposite direction during pump operation to the radial direction radiation RL extending radially Is formed. With such a configuration, in the pump-turbine equipped with the splitter runner of this embodiment, the blade length of the short blade 18 on the band 21 side is shorter than before. FIG. 2 is an exploded schematic view showing the arrangement of the runner vanes 16 on the band 21 side of the runner 15 according to the present embodiment, as viewed from the outside. It can be seen that the position of the short blade 18 is moved in the direction opposite to the rotation direction of the runner 15 compared to the conventional short blade 18a indicated by a broken line on the inlet side of the blade 18 during the pump operation. And by this, long wing 17
The short wing 18 does not exist near the leading edge 22 of
A sufficient width of the flow path can be obtained. Therefore, in the present embodiment, when the pump turbine is operated at a low head due to a change in the operation state,
Even if the flowing water changes so as to flow at the relative speed W from the relative speed W ₀ at the time of the design, and the cavitation CAV is generated around the leading edge 22 of the pressure surface 23 on the band 21 side of the long wing 17, the water grows and grows. Since the width of the flow channel at this portion is sufficiently ensured, the flow channel is unlikely to be blocked. That is, according to the present embodiment, the efficiency is unlikely to decrease even during the low head operation, and as a result, the operating range of the pump operation on the low head side can be widened, and the pump efficiency can be improved. In the present embodiment, the leading edge 19 of the short wing 18 during the pump operation is formed by moving the connection point with the band 21, so that the blade length on the crown 20 side is the same as that of the conventional short wing 18a. Does not change much. Therefore, simply short wing 1
Unlike the wings having a shorter wing length, the crown 20 can have a relatively longer wing length on the side of the crown 20, so that the influence on the wing load and cavitation characteristics of the short wing 18 during operation of the water turbine is minimized. The efficiency during pump operation is improved. [0024] Here, the connection point _{K 1} of the edge line LE and the band 21 of the leading edge 19 of the short blade 18, and the center point O of the spindle (rotation axis) and the origin, and this and edge line LE and the band 21 An angle θ _k1 formed by a virtual straight line connecting the connection points K ₁ on the plane perpendicular to the main axis (rotation axis) with respect to the radial ray RL is _{expressed as follows} : It is desirable to determine so that In determining the rotation angle θ _k1 , the effect of improving the cavitation characteristics during the operation of the pump at a low head, the distribution of the blade load on the short blades 18 during the operation of the turbine, and the cavitation generated on the inlet side during the operation of the turbine. The optimum value is set in consideration of the influence on the characteristics. However, empirically, when the edge line LE is formed linearly on a projection diagram on a plane perpendicular to the main axis (rotation axis), 5 ° ≦ θ _k1 ≦ 10 °
When it comes to the best balance. FIG. 3 shows a second embodiment of the pump-turbine equipped with the splitter runner according to the present invention. As in FIG. 1, the pump-turbine is projected on a plane perpendicular to the center line of the main shaft (rotary shaft) to draw the suction pipe. It is the runner projection line figure seen from the side. The same components as those of the first embodiment are denoted by the same reference numerals. The pump turbine provided with the splitter runner according to the present embodiment also has a short wing 18 in the runner 15.
Leading edge (short wing pump inlet edge) 1 during pump operation
9 is connected to a connection point K ₁ between the edge line LE and the band 21.
Is the edge line LE of the short wing 18 from the center point O of the main shaft (rotation axis).
And through the connection point J ₁ of the crown 20, that are formed so as to be located in the runner rotating direction RV opposite direction during pump operation to the radial direction radiation RL extending radially in the first embodiment Similar, but in this embodiment,
The shape of the edge line LE is a curved line that is convex in the rotation direction RV of the runner 15. That is, in the present embodiment, the edge line L
The polar coordinate display K (r, θ) on a plane perpendicular to the main axis (rotation axis) of E is the connection point J ₁ (r ₀ =
(0, θ ₀ = 0) as a base point, and from this point to the connection point K ₁ (r ₁ , θ ₁ ) with the band 21, the rotation direction RV of the runner 15 is defined as the positive direction of θ. It is configured so that As described above, in the present embodiment, the edge line LE of the leading edge 19 during the pump operation of the short blade 18 is bulged toward the rotation direction RV of the runner 15 compared to the first embodiment. That is, the curve is a convex curve in the rotation direction RV of the runner 15. This makes it possible to keep the blade length of the short wing 18 not particularly short on the crown 20 side and to make the gap between the adjacent long wings 17 sufficiently wide on the band 21 side. That is, according to this embodiment, the short wing 1
Since the length of the turbine 8 does not need to be shortened more than necessary, the load distribution acting on the short wing 18 during the operation of the turbine and the influence on the cavitation characteristics on the inlet side during the operation of the turbine are minimized, and at the same time, at a low head. Due to the cavitation generated on the pressure surface at the leading edge of the long wing 17 on the band 21 during the operation of the pump, the flow path between the long wing 17 and the adjacent short wing 18 can be hardly blocked. As a result, a decrease in efficiency is unlikely to occur even during the pump operation at a low head. As a result, the operating range of the pump operation on the low head side can be widened, and the pump efficiency can be improved. Further, the present embodiment is not limited to this example. For example, as shown in FIG. 4, the edge line LE of the leading edge 19 during the pump operation of the short wing 18 is projected onto a projection plane perpendicular to the main axis (rotation axis). Above, the connection point J ₁ (r ₀ = 0, θ ₀ ) with the crown 20
= 0) to the connection point K ₁ (r ₁ , θ ₁ ) with the band 21, and the intermediate point K _m (r _m , θ _m ) is formed on the straight line of the radial radiation RL, and from there. The tip may be configured to be a curve that is convex in the rotation direction RV of the runner 15. FIG. 5 shows a third embodiment of the pump-turbine equipped with the splitter runner according to the present invention. As in FIG. 1, the pump-turbine is projected on a plane perpendicular to the center line of the main shaft (rotary shaft) to draw the suction pipe. It is the runner projection line figure seen from the side. The same components as those of the first embodiment are denoted by the same reference numerals. The pump turbine having the splitter runner according to the present embodiment also has a short wing 18 in the runner 15.
Leading edge (short wing pump inlet edge) 1 during pump operation
9, the connection point between the edge line LE and the band 21 is
Spindle through the connection point J ₁ of the edge line LE and the crown 20 of the short blade 18 from the center point O of the (rotary shaft), runner rotating direction RV in pump operation with respect to the radial radiation RL extending radially opposite The point that is formed to be located in the direction
In the present embodiment, the shape of the edge line LE is changed in the rotation direction RV of the runner 15 in the same manner as the embodiment and the second embodiment.
It is characterized by having a concave curve. That is, in the present embodiment, the edge line L
The polar coordinate display K (r, θ) on a plane perpendicular to the main axis (rotation axis) of E is the connection point J ₁ (r ₀ =
0, θ ₀ = 0) to the connection point K ₁ (r ₁ ,
θ ₁ ), when the rotation direction of the runner 15 is defined as the positive direction of θ with respect to the curve concave with respect to the rotation direction RV of the runner 15, that is, the connection point J ₁ between the edge line LE and the crown 20. 3] It is formed so that it becomes. [0034] Here, among the edge lines LE, crown 20 and intermediate _{K m (r m, θ m} ) points located in the band 21 is provided, the connection point between the crown _{20 J 1 (r 0 = 0} , θ ₀ =
Points from 0) _K m _{(r m,} up to theta _m) and a concave curve with respect to the rotational direction of the runner 15, the main shaft from the point _{K m} to a connection point between the band _{21 J 2 (r 1, θ} 1) It may be formed so as to be a straight line on a projection on a plane perpendicular to the (rotation axis). With this configuration, as in the second embodiment, the length of the short wings 18 is not reduced so much on the crown 20 side, and the adjacent long wings 17 on the band 21 side. The space between the wings can be made sufficiently wide. In particular, according to this embodiment, the edge line LE of the short wing 18
Is formed in a concave shape with respect to the rotation direction RV of the runner on a projection onto a plane perpendicular to the main axis (rotation axis), so that not only the band 21 side of the leading edge of the long blade 17 but also the crown 20 side during pump operation. (The center point O of the spindle (rotary axis))
Even if cavitation occurs on the side), the cavitation characteristics can be greatly improved. On the side of the crown 20 where cavitation hardly occurs during the operation of the pump, the length of the short wing 18 is made longer.
8 can have a relatively small effect on the load distribution and the cavitation characteristics on the inlet side during the operation of the turbine. That is, according to the present embodiment, the short wing 1 adjacent to the long wing 17 is formed by cavitation generated on the pressure surface of the leading edge of the long wing 17 on the band 21 at the time of pump operation at a low head.
8 can be made less likely to be blocked, so that even during pump operation at a low head, a decrease in efficiency due to cavitation hardly occurs, and as a result, the operating range of the pump operation on the low head side is reduced. Widely used to improve pump efficiency. In the above-described embodiments, the edge line L of the leading edge (short blade pump inlet edge) 19 of the short blade 18 during the pump operation is used.
The E, the connection point of the edge line LE and the band 21, the main shaft passes through the connection point J ₁ from the center point O of the (rotation axis) and the short blade 18 and the crown 20, with respect to the radial radiation RL extending radially And the runner rotation direction RV during the pump operation is formed in the opposite direction.
Although various straight lines or curved lines are formed on a projection line plane with respect to a plane perpendicular to the main axis (rotation axis), the shape of the edge line LE on a flat projection plane perpendicular to the main axis (rotation axis) is defined by the pump water turbine. Depending on the characteristics determined by the location, a straight line, a curve that is convex with respect to the rotation direction RV, or a curve that is concave with respect to the rotation direction RV may be selected and applied. In other words, by applying the shape of the short wing 18 that is optimal to the conditions such as the head and the flow rate determined from the location of the pump turbine according to each of the above-described embodiments, it is possible to minimize the influence on the characteristics during the operation of the turbine.
In addition, it is possible to provide the runner 15 in which the efficiency does not easily decrease even during the pump operation at a low head. As a result, the operating range of the pump operation on the low head side can be widened, and the pump efficiency can be improved. As described above, the pump-turbine equipped with the splitter type runner according to the present invention has a short wing when the long wing and the short wing are alternately arranged along the circumferential direction of the runner. The height edge of the leading edge of the band is arranged at a position opposite to the runner rotation direction during pump operation, and the distance from the height edge of the band-side leading edge of the adjacent long blade is determined. Since the wing is further expanded, even if cavitation occurs on the pressure surface of the long blade, it is difficult to block the flowing water, and the width of the low head operation can be expanded.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment of a pump-turbine equipped with a splitter runner according to the present invention, in which the runner is projected onto a plane perpendicular to a main axis (rotation axis) and viewed from a suction pipe side. Partially notched runner projection diagram. FIG. 2 is an exploded schematic view of the arrangement of runner vanes on the band side of the runner of FIG. 1 as viewed from the outside. FIG. 3 shows a second embodiment of the pump-turbine equipped with the splitter runner according to the present invention, and is a partially cut-out runner projection diagram viewed from the suction pipe side by projecting onto a plane perpendicular to the runner and the main shaft (rotation axis). . FIG. 4 shows a modified example of the second embodiment of the pump-turbine equipped with the splitter runner according to the present invention, and shows a partially cut-out runner projected on a plane perpendicular to the runner and the main shaft (rotation axis) and viewed from the suction pipe side. Projection diagram. FIG. 5 shows a third embodiment of the pump-turbine equipped with the splitter runner according to the present invention, in which the runner is projected onto a plane perpendicular to the main axis (rotation axis) and a partially cut-out runner projection diagram viewed from the suction pipe side. . FIG. 6 is a perspective view showing a runner of a conventional pump-turbine with a band removed from the suction pipe side. FIG. 7 is a plan view showing a splitter runner of a conventional pump-turbine with a band removed from the suction pipe side. FIG. 8 is a partially cut-out runner projection diagram showing a conventional pump-turbine equipped with a splitter runner, projected onto a plane perpendicular to a main shaft (rotation axis) and viewed from a suction pipe side. FIG. 9 is a developed schematic view of the arrangement of runner vanes on the band side of the runner of FIG. 8 as viewed from the outside. DESCRIPTION OF SYMBOLS 3 Runner 7 Runner vane 8 Crown 9 Band 10 Long wing 11 Short wing 12, 13 Front edge 14 Pressure surface 15 Runner 16 Runner vane 17 Long wing 18, 18a Short wing 19 Front edge 20 Crown 21 Band 22 Front edge 23 Pressure surface

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Kotaro Tezuka             2-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa               Toshiba Keihin Works Co., Ltd. (72) Inventor Yasuyuki Enomoto             2-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa               Toshiba Keihin Works Co., Ltd. (72) Inventor Hidetada Arai             1-1-1 Shibaura, Minato-ku, Tokyo Co., Ltd.             Toshiba head office F-term (reference) 3H072 AA17 BB20 CC45 CC85

Claims (1)

Claims: 1. A pump-turbine having splitter runners, both ends of which are supported by a crown and a band, and long blades and short blades are alternately arranged along the circumferential direction of the runner. The edge line at the leading edge during the pump operation is such that the connection point side between the edge line and the band is based on a straight line passing from the rotation center of the splitter runner to the connection point between the edge line and the crown. A pump-turbine provided with a splitter runner formed so as to be located in a direction opposite to the rotation direction of the splitter runner at the time.