JP2001329937A - Francis type pump-turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Francis type pump-turbine reducing occurrence of cavitation and expanding a low output operation range. SOLUTION: In this Francis type pump-turbine, short blades 9a, 9b are arranged in the positions shifted from the central position BCL, which is just in the middle between long blades 9a, 9a facing each other putting the short blades 9b, 9b between them, toward a negative pressure face 11 side of one long blade 9a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Francis-type pump-turbine runner, and more particularly to a Francis-type pump-turbine runner in which long blades and short blades are alternately arranged along the circumferential direction of the runner.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 7, a Francis type pump-turbine runner extends radially from an inner outlet EX to a spiral runner vane toward an outer inlet IN. 1, 1 is formed integrally with the runner 2, and a plurality of runner vanes 1, 1 are arranged along the circumferential direction of the runner 2, and the runner 2 is rotated by the power water W flowing from the inlet IN of the runner 2. With the rotation force, power (rotation torque) is applied to a rotation shaft (main shaft, not shown).

However, in the Francis type pump-turbine shown in FIG. 7, when the head of the motive water W is high, the motive water W flows from the pressure surfaces 3, 3 close to the runner crown side (not shown) of the runner vanes 1, 1. Phenomena appeared, causing cavitation and deteriorating hydraulic performance.

For this reason, the Francis type pump turbine is
As shown in FIG. 8, the runner vanes 1 and 1 are installed on a center position line BCL indicated by a broken line between a long wing 1a having a long camber line extending from the inlet IN to the outlet EX and an adjacent long wing 1a. The short wings 1b, 1b whose camber lines to the exit EX are relatively shorter than the long wings 1a, 1a are arranged, and the long wings 1a, 1a and the short wings 1b, 1b are arranged along the circumferential direction of the runner 2. There has been proposed a Francis-type pump-turbine runner provided with a so-called split-type intermediate blade that is alternately arranged.

The Francis type pump-turbine runner provided with the split-type intermediate blade has a low load per one long blade 1a and has a rectifying effect on the power water W to provide a partial load during the operation of the turbine. The efficiency of the pump is improved, and the pump efficiency is improved due to a decrease in slip at the pump outlet during the operation of the pump. The long blades 1a, 1a and the short blades 1b, 1b have the same blade cross section (profile), and differ only in the length of the camber line.

[0006]

The Francis type pump turbine having the split type intermediate wing shown in FIG. 8 has some inconveniences and disadvantages, one of which is cavitation. There are occurrences.

The Francis type pump-turbine equipped with this split type intermediate blade has a circulation strength based on the blade load on the long blades 1a, 1a during the operation of the turbine, as shown in FIG.
₁ and the strength of the circulation based on the blade load in the short blades 1b, 1b Γ ₂
And Γ ₁ > Γ ₂ , the flow of the motive water W to the runner 2 is reduced to the long blades 1 a, 1 a even if the long and short blades 1 a, 1 a, 1 b, 1 b have the same blade cross section. Angle (inflow angle) between the flow of the local power water W and the circumferential direction of the runner 2
α ₁ and the angle (inflow angle) α ₂ between the circumferential direction of the runner 2 and the local flow of the power water W to the short wings ₁ b, ₁ b are α ₁ > α
_{It has} a relationship of ₂ .

For this reason, in the short blades 1b, 1b, cavitation 4 is likely to be generated on the pressure surface 3 side during the operation of the water turbine, and the flow of the power water W is separated from the pressure surface 3 side, so that the hydraulic performance is reduced. It is a factor of decline. Although the cavitation 4 is likely to be generated during the operation of the turbine with a small output and a small head, the difference becomes more remarkable when the inflow angles α ₁ and α _{2 of} the power water W to the runner ₂ are different. ing.

Generally, in a Francis type pump turbine,
Quick response to fluctuations in power demand is one of the major missions, and usually operates at partial load (low output) and adopts many driving patterns that increase output when power demand increases rapidly. .

Therefore, it is desired to increase the lower limit output (low output) operation width and to improve the efficiency at the time of partial load operation over a long time operation in order to increase the power adjustment allowance.

However, in the Francis pump-turbine equipped with the split-type intermediate blade, the low-power operation in which cavitation is more likely to occur is considered in consideration of the fact that cavitation is generated more at the inlet side of the short blade. There has been a problem that it has become impossible to satisfy the demand for further expanding the low output operation width. In addition, the separation of the power water W on the negative pressure surface 5 of the short blade 1b has directly led to a reduction in efficiency.

The present invention has been made in view of such circumstances, and has as its object to provide a Francis-type pump-turbine runner that suppresses the occurrence of cavitation and further expands the low-power operation range. I do.

[0013]

According to a first aspect of the present invention, there is provided a Francis type pump-turbine which divides a runner vane into a long wing and a short wing in order to achieve the above object. In the Francis type pump turbine in which the long wings and the short wings are alternately arranged along the circumferential direction of the runner, the inlet end and the outlet end of the short wing are arranged in the middle between the long wings facing each other with the boundary therebetween. It is arranged at a position rotated from the center position line toward the suction side of one of the long blades.

According to a second aspect of the present invention, there is provided a Francis type pump-turbine which divides a runner vane into a long wing and a short wing, and separates the runner vane into a long wing and a divided long wing. In a Francis-type pump-turbine in which short wings are alternately arranged along the circumferential direction of the runner, the inlet end of the short wing is arranged on the center line of the middle between the long wings facing each other. The outlet end of the short blade is disposed at a position rotated toward the suction side of the one long blade.

According to a third aspect of the present invention, there is provided a Francis type pump-turbine which divides a runner vane into a long wing and a short wing. in short blade and a Francis pump turbine of which are alternately disposed along the circumferential direction of the runner, the inlet angle of the inlet end of the long wings and beta _1, the inlet angle of the entrance end of the short blades and beta ₂ At this time, the inlet angle β ₁ of the inlet end of the long wing and the inlet angle β of the inlet end of the short wing
₂ is set so that β ₁ > β ₂ , while the outlet end of the short wing is located at the suction surface side of one of the long wings from the center line between the long wings facing each other. It is arranged at a position rotated toward.

According to a fourth aspect of the present invention, there is provided a Francis-type pump-turbine, wherein an inlet end of a short blade passes through a center of rotation of a runner and is connected to the short blade. When the rotation angle from the reference line connected to the entrance end when the arrangement is on the center line between the long wings facing each other at the boundary is θ, and the total number of long and short wings is Zr, the rotation is Angle θ

(Equation 3) Is set in the range.

Further, in order to achieve the above object, the Francis type pump turbine according to the present invention, as described in claim 5, has an outlet end of the short blade passing through the center of rotation of the runner and passing through the short blade. When the rotation angle from the reference line connected to the outlet end when disposed on the center line between the long blades facing each other at the boundary is θ, and the total number of long blades and short blades is Zr, the rotation Angle θ

(Equation 4) Is set in the range.

Also, a Francis pump according to the present invention
The water turbine is described in claim 6 to achieve the above object.
As described above, the runner vanes are divided into long wings and short wings.
The divided long wing and short wing are alternately arranged along the circumferential direction of the runner.
The above-mentioned run
The runner is rotating from the contact point between the circumcircle of Navane and the above long wing
Draw a straight line in the heart, and the straight line intersects the suction surface of the long wing
The distance between a point and the contact point of the long blade is determined by the long blade inlet thickness t._eWhen
And the contact point between the circumcircle of the runner vane and the short wing
Draw a straight line around the runner rotation center, and the straight line
The distance between the point of intersection with the pressure surface and the
Mouth thickness t_sWhere the long blade inlet thickness t _eAnd short wing inlet thickness
Mi t_sAnd t_s> T_eIt is set to.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a Francis type pump-turbine runner according to the present invention will be described below with reference to the drawings and reference numerals attached to the drawings.

FIG. 1 is a meridional sectional view partially showing a first embodiment of a Francis type pump-turbine runner according to the present invention.

The Francis-type pump-turbine runner according to the present embodiment includes a plurality of runner vanes 9 supported by a runner crown 7 and a runner band 8 extending to a runner rotation center axis 6 and arranged along the circumferential direction. At the same time, when a flow path is formed between the plurality of runner vanes 9 and the power water W flowing from the inlet IN of the runner vane 9 flows through the flow path as the streamline SL toward the outlet EX, the power water W has The energy is converted into rotational torque and applied to the runner rotation center shaft 6 to drive the generator via the rotation shaft (main shaft).

On the other hand, as shown in FIG. 2, the runner vane 9 is divided into long blades 9a, 9a and short blades 9b, 9b, and the divided long blades 9a, 9a and short blades 9b, 9b are alternately runner-vane. It is configured to include a so-called split-type intermediate wing arranged along the circumferential direction of No. 10.

Further, the short wings 9b, 9b located between the long wing 9a and the adjacent long wing 9a have a center position line BC indicated by a broken line in the middle between the long wings 9a, 9a facing each other.
It is disposed on the negative pressure surface 11 side of one of the long blades 9a from L to the counterclockwise direction (runner rotation direction during pump operation).

Further, the exit end EXP of the short wings 9b, 9b
Passes through the runner rotational center O _10, short blade 9b, long blade 9a that faces each other the boundary of 9b, reference line Ls connecting to the outlet end of the case of arranging the middle of center lines on the BCL between 9a
, The long wings 9a, 9b and the short wings 9b, 9
When the total number of sheets with b is Zr, the rotation angle θ of the exit end EXP is

(Equation 5) Is set in the range. In the present embodiment,
For convenience of explanation, only the rotation angle θ of the outlet end EXP at the short blades 9b, 9b is described, but the same applies to the rotation angle θ at the inlet end INP.

[0025] In this case, through the runner rotational center O _10, and the inlet end INP from the reference line Ls connecting to the inlet end INP of when placed in a central position line on the BCL to the rotation angle theta.

FIG. 2 shows a pressure distribution line Pmin-1 acting on the pressure surface of the long wing and a pressure distribution line Pmin acting on the pressure surface of the short wing.
5 is a pressure distribution diagram comparing min-s with experimental data showing the minimum pressure Pmin on the vertical axis and the rotation angle θ on the horizontal axis. That is, in FIG. 2, when the rotation angle of the short wing is increased,
Although the minimum pressure Pmin acting on the inlet pressure surface of the long blade is reduced by an increase in the rotation angle, the minimum pressure acting on the inlet pressure surface of the short blade is increased, and the shortest pressure Pmin is shorter than that of the long blade. The wings can suppress cavitation that has been generated more frequently, and this means that cavitation can be suppressed more than before in consideration of the total of the long wing and the short wing. In FIG. 2, the rotation angle θ = 360 ×
If ({1 / Zr)-(1 / (Zr + 2))} [deg.] Exceeds this value, the flow path formed by the long blades and the short blades is an area that is too narrow to manufacture, so the upper limit is set. Is the limit.

As described above, in the present embodiment, the short wings 9b,
9b, the central position line BCL at the inlet end and the outlet end
And the rotation angle θ of the inlet end INP and the outlet end EXP of the short blades 9b, 9b is set to 0 <θ <360.
Since it is set in the range of {(1 / Zr)-(1 / (Zr + 2))}, cavitation can be further suppressed as compared with the related art, and the low output operation width can be further expanded.

FIG. 4 is a plan view showing a second embodiment of the Francis type pump-turbine according to the present invention. The first
The same reference numerals are given to the same parts as the constituent parts or corresponding parts shown in the embodiment.

The Francis pump-turbine according to the present embodiment has the inlet end I of the short blades 9b, 9b at the center position line BCL indicated by a broken line in the middle between the long blade 9a and the adjacent long blade 9a.
Established the NP long blade 9a, together to an equal distribution of the pitch P between 9a, as in the first embodiment, as the runner rotational center O _10, facing each other on the border short blades 9b, 9b, the sum of the Tsubasa Cho 9a, a rotational angle from the reference line Ls connecting the outlet end EXP when placed in the middle of the center line on the BCL between 9a and theta _1, the long blade 9a, 9a and short wings 9b, 9b When the number is Zr, the exit end EXP of the short wings 9b, 9b
To the negative pressure surface 11 side of one of the long blades 9a, and the rotation angle θ ₁ is

(Equation 6) Is set in the range. In the present embodiment,
The wing cross-sectional shape of the long wings 9a, 9a and the wing cross-sectional shape of the short wings 9b, 9b are different from each other, which is different from that shown in the first embodiment.

As described above, in the present embodiment, the short wing 9a is positioned on the center position line BCL between the long wing 9a and the adjacent long wing 9a.
The inlet ends INP of the short blades 9b and 9b are arranged so that the pitch P between the short blades 9a and 9b is equal to the inlet angle (mounting angle) of the short blades 9b and 9b. , The power water W can be guided to the inlet of the runner 10 satisfactorily, and the pressure surfaces 1 of the short blades 9b, 9b can be reduced.
2 can further reduce cavitation and prevent a decrease in hydraulic performance due to a separation phenomenon of the motive water W.

Further, this embodiment, like the first embodiment, the rotation angle and theta _1, the long blade 9a, 9a and short wings 9b, 9
When the total number of the short blades 9b and 9b is Zr, the outlet ends EXP of the short blades 9b and 9b are directed toward the negative pressure surface 11 of one of the long blades 9a.
And the rotation angle θ ₁

(Equation 7) , The strength of the circulation of the short wings 9b, 9b can be increased to approach the strength of the circulation of the long wings 9a, 9a, and the power water W You can do more work.

Therefore, in the present embodiment, the cavitation generated in the short wings is suppressed, and the wing load of the short wings is increased so that more work is performed by the power water W. It can be further expanded.

FIG. 5 is a plan view showing a third embodiment of the Francis type pump-turbine according to the present invention. The first
The same reference numerals are given to the same parts as the constituent parts or corresponding parts shown in the embodiment.

The pump-turbine of Francis according to the present embodiment, the long blade 9a, the inlet angle of the inlet end INP ₁ and beta ₁ in 9a, short blade 9b, the entrance angle of the inlet blades INP ₂ in 9b beta ₂ and In this case, a relational expression of β ₁ > β ₂ is provided between the inlet angle β ₁ of the inlet end INP ₁ of the long blades 9 a and 9 a and the inlet angle β ₂ of the inlet end INP ₂ of the short blades 9 b and 9 b. , as in the first embodiment and the second embodiment, the rotation angle and theta _2, the long wings 9a, 9a and short wings 9
Assuming that the total number of the short wings 9b and 9b is Zr,
b directs the negative pressure surface 11 side of one of the long blade 9a to the outlet end EXP from the center position line BCL the middle of the long blade 9a beside the long blades 9a of, and the rotation angle theta _2,

(Equation 8) Is set in the range. The pitch P between the inlet end INP ₂ at the inlet end INP ₁ and short wings 9b, 9b in the Tsubasa Cho 9a, 9a are isosteric may be any unequal distribution.

As described above, according to the present embodiment, the long wings 9a, 9
the inlet of the inlet end INP ₁ in a angle beta ₁ and short wings 9b, 9
b and the entrance angle β ₂ of the entrance end INP ₂ is β ₁ > β ₂
And the exit end EXP of the short wings 9b, 9b is set at the center position line BCL between the long wing 9a and the adjacent long wing 9a.
One was directed to the suction side 11 of the long blade 9a, and the rotation angle theta ₂ from

(Equation 9) , The motive power W can be guided to the inlet of the runner 10 satisfactorily to suppress cavitation, and the power of the wings 9b, 9b can be increased by increasing the wing load accompanying the increase in the circulation strength. More work can be done with water W.

Therefore, according to the present embodiment, the low-power operation width can be further expanded as compared with the related art by suppressing cavitation and increasing the blade load.

FIG. 6 shows a fourth embodiment of a Francis type pump-turbine according to the present invention, and is a partially cutaway partial view in which long blades and short blades are overlapped and compared for convenience of explanation. The same components as those in the first embodiment are denoted by the same reference numerals.

The Francis pump-turbine according to the present embodiment has a blade cross-sectional shape (profile) on the inlet side of the long blades 9a, 9a and the short blades 9b, 9b alternately arranged along the circumferential direction of the runner 10. It differs from the wing cross-sectional shape on the inlet side.

Of the long wings 9a, 9a and the short wings 9b, 9b alternately arranged along the circumferential direction of the runner 10, the long wings 9a, 9a are represented by broken lines, and
b and 9b are represented by solid lines.

The Tsubasa Cho 9a, 9a is a straight line is drawn circumscribed circle 13 and the long blade 9a of runner vanes 9, the contact point TPe of 9a in runner rotational center _{O 10,} the straight line Le is long blades 9a, 9
negative pressure surface 11 and the intersection between CPe and long blade 9a of a, the distance between 9a contacts TPe the long blades entry thickness _{t e.}

The short wings 9b, 9b are connected to the long wings 9a, 9a.
Similarly, the circumcircle 13 of the runner vane 9 and the short wings 9b, 9
from the contact TPs and b a straight line is drawn runner rotational center _{O 10,} the straight line Ls is short blades 9b, the suction surface 11 and the intersection between CPs and short wings 9b of 9b, 9b distance short wings entry thickness of the contact TPs of and t _s.

At this time, the relationship between the long blade inlet thickness t _e and the short blade inlet thickness t _s is

[Number 10] in which was set to _t s> _{t e.}

Generally, the long wings 9a, 9a and the short wings 9b, 9b
In the runner vane 9 having the split-type intermediate wing, the cavitation is largely caused by the cross-sectional shape of the wing on the inlet side of both the long wings 9a, 9a and the short wings 9b, 9b. It is considered that making the wing cross-sectional shape that has little effect on the change is an important technical matter in suppressing cavitation.

[0044] The present embodiment, attention is paid to this point, long blades entry thickness t of the relation between _e and the short wings entry thickness t _s, t _s> shorter blades 9b by setting t _e, Since the pressure drop of the power water W flowing on the pressure surface 12 of the short wing 9b is prevented, cavitation generated from the short wings 9b, 9b can be suppressed.

Therefore, in the present embodiment, since the occurrence of cavitation is suppressed, the low output operation width can be expanded. In particular, if at least one of the first to third embodiments is selected and combined with this embodiment, the low-output operation width can be further increased.

[0046]

As described above, the Francis-type pump turbine according to the present invention divides the runner vane into long blades and short blades, and separates the divided long blades and short blades along the circumferential direction of the runner. While having split-type intermediate wings arranged alternately, the wing load on the short wings was increased to allow more work to be done by the power water, and cavitation generated on the inlet side of the short wing where the power water flows in was suppressed. In addition, the low output operation width can be further expanded.

[Brief description of the drawings]

FIG. 1 is a meridional sectional view partially showing a first embodiment of a Francis type pump-turbine runner according to the present invention.

FIG. 2 is a plan view of the Francis-type pump-turbine runner according to the present invention as viewed along the streamline shown in FIG.

FIG. 3 is a pressure distribution diagram comparing a pressure distribution line acting on a pressure surface of a long blade with a pressure distribution line acting on a pressure surface of a short blade in a Francis type pump-turbine runner according to the present invention.

FIG. 4 shows a second embodiment of the Francis pump turbine according to the present invention.
FIG. 2 is a plan view showing the embodiment.

FIG. 5 shows a third embodiment of a Francis type pump turbine according to the present invention.
FIG. 2 is a plan view showing the embodiment.

FIG. 6 shows a fourth embodiment of the Francis pump turbine according to the present invention.
The partially cutaway partial view which showed embodiment and compared the long wing and the short wing by overlapping.

FIG. 7 is a plan view showing a conventional Francis type pump-turbine.

FIG. 8 is a plan view showing a Francis-type pump-turbine provided with a conventional split type intermediate blade.

FIG. 9 is a conceptual diagram used to explain a phenomenon occurring in a Francis type pump turbine having a conventional split type intermediate blade.

[Explanation of symbols]

 Reference Signs List 1 liner vane 1a long blade 1b short blade 2 runner 3 pressure surface 4 cavitation 5 suction surface 6 runner rotation center axis 7 runner crown 8 runner band 9 runner vane 9a long blade 9b short blade 10 runner 11 suction surface 12 pressure surface 13 circumscribed circle

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kotaro Tezuka 2-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside the Toshiba Keihin Works Co., Ltd. (72) Takaki Nakamura 2-chome, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa 4 Toshiba Corporation Keihin Plant (72) Inventor Hidetada Arai 1-1-1, Shibaura, Minato-ku, Tokyo F-term (reference) 3H072 AA07 BB20 BB31 CC44

Claims (6)

[Claims] 1. A Francis type pump turbine in which a runner vane is divided into long blades and short blades, and the divided long blades and short blades are alternately arranged along the circumferential direction of the runner. And a discharge end disposed at a position rotated from the center line between the long blades facing each other with the boundary toward the suction side of one of the long blades. . 2. A Francis type pump-turbine wherein a runner vane is divided into long blades and short blades, and the divided long blades and short blades are alternately arranged along the circumferential direction of the runner. Was arranged on the center line between the long wings facing each other, and the outlet end of the short wing was arranged at a position rotated toward the suction side of the one long wing. A Francis type pump-turbine characterized by that: 3. A Francis type pump-turbine wherein a runner vane is divided into long blades and short blades, and the divided long blades and short blades are alternately arranged along the circumferential direction of the runner. the inlet angle and beta _1, the when the entrance angle of the inlet end of the short blades and beta _2, the relationship between the inlet angle beta ₂ at the inlet end in the inlet angle beta ₁ and the short blades of the inlet end of the long wings Is set to β ₁ > β _2, and the outlet end of the short blade is rotated from the center line between the long blades facing each other to the suction surface side of the one long blade. A Francis-type pump-turbine, which is arranged at the position where it is set. 4. The inlet end of the short wing passes through the center of rotation of the runner, and is located on a center line between the long wings facing each other with the short wing as a boundary. When the rotation angle is θ and the total number of long and short blades is Zr, the rotation angle θ is given by: The Francis-type pump-turbine according to claim 1, wherein the pump-turbine is set in a range of: 5. An outlet end of the short blade passes through a center of rotation of the runner and is located on a center line between the long blades facing each other with the short blade as a boundary. When the rotation angle is θ and the total number of long and short blades is Zr, the rotation angle θ is given by: The Francis type pump-turbine according to claim 1, wherein the pump-turbine is set in the range of: 6. A Francis type pump-turbine wherein a runner vane is divided into long blades and short blades, and the divided long blades and short blades are alternately arranged along the circumferential direction of the runner. A straight line is drawn from the contact point with the long blade to the center of rotation of the runner, and the distance between the point where the straight line intersects the suction surface of the long blade and the contact point of the long blade is defined as the long blade inlet thickness t _e , When a straight line is drawn from the contact point between the circle and the short wing to the center of rotation of the runner, and the distance between the point where the straight line intersects the suction surface of the short wing and the contact point of the short wing is the short wing inlet thickness t _s , long blade entry thickness t _e and short wings inlet and thickness t _s, t _s> Francis pump-turbine, characterized in that set to t _e.