JP2015059512A - Hydraulic machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic machine capable of reducing an axial thrust force acting on a runner even if an aperture and the number of balance pipes increase.SOLUTION: According to one embodiment, a hydraulic machine includes: a runner converting energy of water flowing from a casing to rotational energy; a spindle transmitting the rotational energy of the runner to a generator; and a draft pipe into which the water driving the runner flows. The machine also includes a balance pipe including a first opening portion opening to a back pressure chamber adjacent to the runner and a second opening portion opening into the draft pipe. The machine further includes a pressure regulation mechanism provided near the second opening portion within the draft pipe, and generating an eddy of the water near the second opening portion so as to regulate an internal pressure of the back pressure chamber.

Description

  Embodiments described herein relate generally to a hydraulic machine.

  FIG. 9 is a longitudinal sectional view showing the structure of a general hydraulic machine. This hydraulic machine is equivalent to a Francis turbine.

  During the power generation operation, water flows from the casing 1 through the stay vane 2 and the guide vane 3 into the runner 4. The runner 4 includes a plurality of blades 4a, a crown 4b connected to the blades 4a from above, and a band 4c connected to the blades 4a from below. The runner 4 is rotationally driven by water flowing from the casing 1, and converts the energy of the water into rotational energy. A symbol R indicates the rotation direction of the runner 4. The water that has driven the runner 4 flows into the suction pipe 5 and flows out to the water discharge channel.

  The rotational energy of the runner 4 is transmitted to the generator 7 via the main shaft 6 that rotates together with the runner 4. Reference symbol Z indicates a rotation axis of the main shaft 6. The runner 4 is housed between the upper cover 8 and the lower cover 9, and a space called a back pressure chamber 10 exists between the back surface of the runner 4 and the upper cover 8.

  The hydraulic machine of FIG. 9 further includes a balance pipe 11 having a pipe inlet 11 a opened in the back pressure chamber 10 adjacent to the runner 4 and a pipe outlet 11 b opened inside the suction pipe 5. As a result, the back pressure chamber 10 and the inside of the suction pipe 5 are connected by the balance pipe 11. The hydraulic machine shown in FIG. 9 includes one balance pipe 11, but may include a plurality of balance pipes 11.

  FIG. 10 is a diagram showing a pressure distribution around a runner of a general hydraulic machine.

In a hydraulic machine, if there is an imbalance between the pressure applied to the upper side of the runner 4 and the pressure applied to the lower side of the runner 4, an axial thrust force (axial thrust force) is generated. Usually, since the force F ₁ for pushing down the runner 4 is stronger than the force F ₂ for pushing up the runner 4, a downward axial thrust force is applied to the runner 4. By supporting the runner 4 with a thrust bearing having a capacity suitable for the axial thrust force, the hydraulic machine can be stably operated. However, when the downward axial thrust force is large, the loss in the thrust bearing is increased, and a thrust bearing having a large capacity is required, which increases the price of the hydraulic machine.

  In order to reduce the axial thrust force, one or more balance pipes 11 that connect the back pressure chamber 10 and the inside of the suction pipe 5 may be installed to reduce the pressure in the back pressure chamber 10. In this case, the axial thrust force is reduced by increasing the diameter and number of the balance pipes 11 to increase the cross-sectional area of the balance pipe 11. However, when the cross-sectional area of the balance pipe 11 is excessively large, a decrease in the turbine efficiency due to an increase in the leakage flow rate is caused. Therefore, the balance pipe 11 adjusted to an appropriate cross-sectional area is usually attached.

  Moreover, when installing the balance pipe 11, it receives the restrictions on the structure of the building which accommodates a hydraulic machine. Therefore, there is a limit to increasing the diameter and number of the balance pipes 11, and the effect of reducing the axial thrust force by the balance pipe 11 is limited. In addition, since the balance pipe 11 is normally embedded in concrete when the hydraulic machine is installed, it is often impossible to increase the diameter and number of the balance pipes 11 after the embedding and the start of operation.

  In recent years, there is a case where a request to reduce the axial thrust force applied to the runner 4 may occur at the time of repairing an existing hydraulic machine. However, for the above reasons, it is often impossible to reduce the axial thrust force by increasing the diameter and number of the balance pipes 11. As a method for solving this, there is a method of providing a rectifier for increasing the flow rate of water in the suction pipe 5 in the vicinity of the pipe outlet 11b in order to increase the flow rate in the balance pipe 11. However, in this method, it is necessary to attach a relatively large plate to the suction pipe 5.

JP2012-92712A

  An object of the present invention is to provide a hydraulic machine capable of reducing the axial thrust force applied to the runner without increasing the diameter or number of balance pipes.

  According to one embodiment, the hydraulic machine drives a runner that converts energy of water flowing from the casing into rotational energy, a main shaft that transmits the rotational energy of the runner to a generator, and the runner. A suction pipe into which the water flows. Further, the machine includes a balance pipe having a first opening opened in a back pressure chamber adjacent to the runner and a second opening opened inside the suction pipe. Further, the machine is provided near the second opening inside the suction pipe, and adjusts the pressure in the back pressure chamber by generating a vortex of the water near the second opening. Provide mechanism.

It is a longitudinal cross-sectional view which shows the structure of the hydraulic machine of 1st Embodiment. It is an expanded vertical sectional view which shows the structure of the hydraulic machine of 1st Embodiment. It is a longitudinal cross-sectional view which shows the water flow in the suction pipe at the time of the small flow rate driving | operation of 1st Embodiment, the design point vicinity, and the high flow rate driving | operation. It is a graph which shows the relationship between the flow volume and flow angle in a general hydraulic machine. It is a graph which shows the relationship between the flow volume and axial thrust force in a general hydraulic machine. It is a graph which shows the relationship between the flow volume and axial thrust force in the hydraulic machine of 1st Embodiment. It is a longitudinal cross-sectional view which shows the structure of the hydraulic machine of 2nd Embodiment. It is a longitudinal cross-sectional view which shows the structure of the hydraulic machine of the modification of 2nd Embodiment. It is a longitudinal cross-sectional view which shows the structure of a general hydraulic machine. It is a figure which shows the pressure distribution around the runner of a general hydraulic machine.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings referred to in this specification, the same or similar components are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a longitudinal sectional view showing the structure of the hydraulic machine according to the first embodiment. This hydraulic machine is equivalent to a Francis turbine.

  This hydraulic machine includes a casing 1, a stay vane 2, a guide vane 3, a runner 4 having a plurality of blades 4a, a crown 4b, and a band 4c, a suction pipe 5, a main shaft 6, a generator 7, A cover 8, a lower cover 9, and a back pressure chamber 10 are provided.

  The hydraulic machine further includes a balance pipe 11 having a pipe inlet 11 a opened in the back pressure chamber 10 adjacent to the runner 4 and a pipe outlet 11 b opened inside the suction pipe 5. The pipe inlet 11a and the pipe outlet 11b are examples of first and second openings, respectively.

  The hydraulic machine further includes a pressure adjusting mechanism 12 provided in the vicinity of the pipe outlet 11b inside the suction pipe 5. The pressure adjustment mechanism 12 of the present embodiment is a protrusion protruding from the inner wall surface of the suction pipe 5 and is disposed on the upstream side of the pipe outlet 11b. The pressure adjustment mechanism 12 may be attached in advance when the hydraulic machine is newly installed, or may be attached when the hydraulic machine is repaired. Details of the pressure adjustment mechanism 12 will be described later.

  FIG. 2 is an enlarged longitudinal sectional view showing the structure of the hydraulic machine according to the first embodiment. 2A is a cross-sectional view of the pressure adjustment mechanism 12 as viewed in the direction A in FIG. 1, and FIG. 2B is a cross-sectional view of the pressure adjustment mechanism 12 as viewed from the same viewpoint as FIG. .

  The X axis indicates a direction parallel to the rotation direction of the runner 4. The + X direction corresponds to the rotation direction of the runner 4, and the −X direction corresponds to the reverse direction of the rotation direction of the runner 4. The Y axis indicates a direction parallel to the rotation axis Z of the main shaft 6. The + Y direction is a direction from the downstream side to the upstream side in parallel to the rotation axis Z, and the -Y direction is a direction from the upstream side to the downstream side in parallel to the rotation axis Z.

  The pressure adjustment mechanism 12 of the present embodiment has a plate shape, and a plane E parallel to the pressure adjustment mechanism 12 is inclined with respect to the Y axis. A symbol θ represents an inclination angle of the plane E with respect to the −Y direction. In this embodiment, the inclination angle θ is set to 45 degrees to 110 degrees (the positive direction of the inclination angle θ is the + X direction). That is, the plane E parallel to the pressure adjusting mechanism 12 is 45 degrees to 110 degrees in the rotation direction (+ X direction) of the runner 4 with respect to the direction from the upstream side to the downstream side (−Y direction) parallel to the rotation axis Z. Inclined. Details of the inclination angle θ will be described later.

  As shown in FIG. 2B, the pressure adjusting mechanism 12 of the present embodiment can adjust the pressure in the back pressure chamber 10 by generating a vortex of water near the pipe outlet 11b. Hereinafter, the function of the pressure adjustment mechanism 12 of this embodiment will be described.

  In a normal operation of a general hydraulic machine, since the force for pushing down the runner 4 is stronger than the force for pushing up the runner 4, a downward axial thrust force is applied to the runner 4. It is the pressure in the back pressure chamber 10 that greatly affects the axial thrust force. If the pressure in the back pressure chamber 10 can be reduced, the axial thrust force can be reduced.

  On the other hand, the balance pipe 11 is installed so as to communicate the back pressure chamber 10 and the inside of the suction pipe 5. Therefore, if the pressure in the vicinity of the pipe outlet 11b can be reduced, the pressure in the back pressure chamber 10 can be reduced and the axial thrust force can be reduced.

  Therefore, in the present embodiment, the pressure adjusting mechanism 12 is provided in the vicinity of the pipe outlet 11 b inside the suction pipe 5. When a water flow hits the pressure adjustment mechanism 12, a vortex is generated on the downstream side of the pressure adjustment mechanism 12. Since the pressure at the center of the vortex is lower than the surrounding pressure, the pressure is reduced downstream of the pressure adjusting mechanism 12. In some cases, the pressure on the downstream side of the pressure adjustment mechanism 12 decreases as cavitation occurs.

  The pressure adjusting mechanism 12 of the present embodiment is disposed on the upstream side of the pipe outlet 11b in the vicinity of the pipe outlet 11b. Therefore, the vortex is generated near the pipe outlet 11b. Therefore, the pressure in the vicinity of the pipe outlet 11b decreases due to the influence of the pressure decrease due to the vortex. As a result, the pressure in the back pressure chamber 10 is reduced, and the axial thrust force is reduced.

  Reference symbol D indicates the diameter of the pipe outlet 11b, and reference symbol L indicates the length of the pressure adjustment mechanism 12 in the direction parallel to the XY plane. The length L of the pressure adjusting mechanism 12 is preferably longer than the diameter D of the pipe outlet 11b, but is preferably not too long compared to the diameter D of the pipe outlet 11b. The reason is that if the length L is too short, a sufficiently large vortex does not occur, and if the length L is too long, the pressure adjusting mechanism 12 hinders the water flow.

  A symbol K indicates a direction perpendicular to the rotation axis Z of the main shaft 6. The pressure adjustment mechanism 12 of the present embodiment has a plate shape extending in a direction parallel to the XY plane and in the K direction.

  FIG. 3 is a longitudinal sectional view showing a water flow in the suction pipe 5 at the time of small flow rate operation, near the design point, and at the time of high flow rate operation of the hydraulic machine of the first embodiment.

  When the hydraulic machine is operating near the design point, the flow velocity of the water flow in the suction pipe 5 has almost no swirling component, and water flows in the vertical direction (see FIG. 3B). On the other hand, when the hydraulic machine is operating on the larger flow rate side than the design point, the water in the suction pipe 5 turns and flows in the direction opposite to the rotation direction of the runner 4 (see FIG. 3C). Further, when the hydraulic machine is operating at a smaller flow rate than the design point, the water in the suction pipe 5 swirls in the same direction as the rotation direction of the runner 4 (see FIG. 3A). Thus, the water flow in the suction pipe 5 changes according to the operating state of the hydraulic machine. The same applies to general hydraulic machines.

  FIG. 4 is a graph showing the relationship between the flow rate and the flow angle in a general hydraulic machine, and FIG. 5 is a graph showing the relationship between the flow rate and the axial thrust force in a general hydraulic machine.

  4 and 5 show relative flow rates when the flow rate of the water flow in the suction pipe 5 is 1 when the hydraulic machine is operating near the design point. 4 and 5 indicate the flow angle near the pipe outlet 11b and the axial thrust force applied to the runner 4 when the balance pipe 11 is installed in the hydraulic machine.

  When the relative flow rate is smaller than 1, the flow angle and the axial thrust force are small. As the flow rate increases, the flow angle and the axial thrust force increase. However, when the flow rate becomes larger than the design point flow rate (that is, when the relative flow rate becomes larger than 1), the axial thrust force gradually decreases.

  The pressure adjusting mechanism 12 of this embodiment is desirably installed so that the pressure in the vicinity of the pipe outlet 11b decreases during operation with a large axial thrust force. According to FIG. 5, the axial thrust force is large when the relative flow rate is greater than 0.55. Further, according to FIG. 4, when the relative flow rate is larger than 0.55, the flow angle is about 45 to 110 degrees.

  Therefore, in this embodiment, the inclination angle θ of the pressure adjustment mechanism 12 is set to 45 degrees to 110 degrees so that the pressure adjustment mechanism 12 faces a water flow having a flow angle of 45 degrees to 110 degrees. .

  As a result, when the hydraulic machine is operating near the design point or at a large flow rate, the water flow easily hits the pressure adjusting mechanism 12, and the pressure near the pipe outlet 11b can be reduced when the axial thrust force is large. In addition, during a small flow rate operation where the flow angle is less than 45 degrees, water generally flows along the pressure adjustment mechanism 12, so that the occurrence of loss due to the pressure adjustment mechanism 12 can be suppressed.

  FIG. 6 is a graph showing the relationship between the flow rate and the axial thrust force in the hydraulic machine of the first embodiment.

A curve C ₁ shows the axial thrust force when the pressure adjusting mechanism 12 is not installed. Curve C ₂ shows the axial thrust force when the pressure adjustment mechanism 12 is installed. In the case of the curve C ₂ , the inclination angle θ of the pressure adjustment mechanism 12 is set to 45 degrees to 110 degrees. According to FIG. 6, it can be seen that the shaft thrust force when the pressure adjustment mechanism 12 is installed is reduced compared to the shaft thrust force when the pressure adjustment mechanism 12 is not installed during operation with a large shaft thrust force.

  FIG. 3A shows the water flow in the suction pipe 5 during the small flow rate operation. During the actual operation, the direction of the water flow is generally parallel to the pressure adjustment mechanism 12. Therefore, since water flows along the pressure adjustment mechanism 12, the pressure drop near the pipe outlet 11b hardly occurs.

  FIG. 3B shows the water flow in the suction pipe 5 when the hydraulic machine is operating near the design point. During the actual operation, the water flow has a slight turning speed component. However, since the water flows at a large flow angle, the pressure decreases on the downstream side of the pressure adjustment mechanism 12.

  FIG.3 (c) shows the water flow in the suction pipe 5 at the time of a large flow rate driving | operation. During the actual operation, the water flow has a turning speed component in the direction opposite to the rotation direction of the runner 4. Therefore, since water flows so as to face the pressure adjustment mechanism 12, the pressure decreases on the downstream side of the pressure adjustment mechanism 12.

  As described above, the hydraulic machine of the present embodiment is provided in the vicinity of the pipe outlet 11b inside the suction pipe 5, and generates a vortex of water near the pipe outlet 11b to adjust the pressure in the back pressure chamber 10. An adjustment mechanism 12 is provided. Therefore, according to the present embodiment, the axial thrust force applied to the runner 4 can be reduced without increasing the diameter or number of the balance pipes 11. For example, according to the present embodiment, the axial thrust force of an existing hydraulic machine can be reduced by a simple construction in which the pressure adjusting mechanism 12 is attached when the hydraulic machine is repaired.

  In addition, the pressure adjustment mechanism 12 of the present embodiment is disposed to be inclined with respect to a direction parallel to the rotation axis Z, and specifically, the inclination angle θ is set to 45 degrees to 110 degrees. Therefore, according to the present embodiment, it is possible to suppress the occurrence of loss in an operating state with a small axial thrust force while reducing the axial thrust force in an operating state with a large axial thrust force.

Symbols S ₁ and S _{2 in} FIG. 1 indicate outer wall surfaces on the outer peripheral side and inner peripheral side of the suction pipe 5. The sign S ₃ of FIG. 1 shows an outer wall surface located between these surfaces S _1, S _2. Although the balance pipe 11 of the present embodiment is provided near the outer wall surface S ₁ , it may be provided near the outer wall surface S ₂ or near the outer wall surface S ₃ . Moreover, although the hydraulic machine of the present embodiment includes one balance pipe 11, the hydraulic machine may include a plurality of balance pipes 11.

(Second Embodiment)
FIG. 7 is a longitudinal sectional view showing the structure of the hydraulic machine according to the second embodiment. 7A is a cross-sectional view of the pressure adjustment mechanism 12 as viewed in the direction A in FIG. 1, and FIG. 7B is a cross-sectional view of the pressure adjustment mechanism 12 as viewed from the same viewpoint as FIG. .

  Similar to the first embodiment, the pressure adjustment mechanism 12 of the present embodiment is a protrusion protruding from the inner wall surface of the suction pipe 5 and is disposed on the upstream side of the pipe outlet 11b. However, the pressure adjusting mechanism 12 of the present embodiment has a curved shape along the pipe outlet 11b, and specifically has a shape obtained by cutting a tubular member in half.

  Since the pressure adjustment mechanism 12 of the present embodiment has a curved shape, the pressure adjustment mechanism 12 faces the water flow at various flow angles. Therefore, according to the present embodiment, the axial thrust force applied to the runner 4 can be effectively reduced.

The pressure adjustment mechanism 12 of the present embodiment, as the arrow P ₁ shown in FIG. 7 (a), and is rotatable in the circumferential direction of the pipe outlet 11b. Such a structure can be realized, for example, by providing a rail for moving the pressure adjusting mechanism 12 around the pipe outlet 11b and providing the driving unit and the remote control unit in the pressure adjusting mechanism 12. According to this embodiment, when there is no need to reduce the axial thrust force, the pressure adjusting mechanism 12 can be moved to a position where the amount of reduction of the axial thrust force becomes small.

The pressure adjusting mechanism 12 of this embodiment, as indicated by arrow P ₂ shown in FIG. 7 (b), the length of the perpendicular direction K to the rotation axis Z is telescopically configured to vary. That is, when the pressure adjustment mechanism 12 expands and contracts, the length of the pressure adjustment mechanism 12 in the K direction increases or decreases. According to this embodiment, when there is no need to reduce the axial thrust force, the length of the pressure adjusting mechanism 12 can be shortened to a length that reduces the reduction amount of the axial thrust force.

  FIG. 8 is a longitudinal sectional view showing the structure of a hydraulic machine according to a modification of the second embodiment. 8A is a cross-sectional view of the pressure adjustment mechanism 12 as viewed in the direction A of FIG. 1, and FIG. 8B is a cross-sectional view of the pressure adjustment mechanism 12 as viewed from the same viewpoint as FIG. .

  The pressure adjustment mechanism 12 of this modification is a protrusion protruding from the inner wall surface of the suction pipe 5 as in the first embodiment. However, the pressure adjustment mechanism 12 of the present modification has a tubular shape surrounding the pipe outlet 11b. According to this modification, the axial thrust force applied to the runner 4 can be effectively reduced by the pressure adjusting mechanism 12 facing the water flow at various flow angles.

  Further, in the pressure adjusting mechanism 12 of this modification, the length in the K direction perpendicular to the rotation axis Z is different between the upstream portion 12a and the downstream portion 12b of the pipe outlet 11b. Specifically, the length in the K direction of the downstream portion 12b of the pressure adjusting mechanism 12 is set to be shorter than the length in the K direction of the upstream portion 12a of the pressure adjusting mechanism 12. This makes it possible to give the pressure adjustment mechanism 12 of FIG. 8 the same function as the pressure adjustment mechanism 12 of FIG.

  The front end surface of the pressure adjusting mechanism 12 of this modification is a non-perpendicular plane with respect to the K direction. The symbol φ indicates the angle of the front end surface of the pressure adjusting mechanism 12 with respect to the K direction. The angle φ in this modification is set to 45 degrees or less. Thereby, the shape of the pressure adjustment mechanism 12 of FIG. 8 can be brought close to the shape of the pressure adjustment mechanism 12 of FIG.

The pressure adjustment mechanism 12 of this modification, as indicated by arrow P ₁ shown in FIG. 8 (a), and is rotatable in the circumferential direction of the pipe outlet 11b. The pressure adjusting mechanism 12 of this modification, as indicated by arrow P ₂ shown in FIG. 8 (b), the length of the perpendicular direction K to the rotation axis Z is telescopically configured to vary.

Note that the rotatable structure as indicated by the arrow P ₁ and the expandable and contractable structure as indicated by the arrow P ₂ are also applicable to the pressure adjusting mechanism 12 of the first embodiment.

  As described above, the hydraulic machine of the present embodiment is provided in the vicinity of the pipe outlet 11b inside the suction pipe 5, and generates a vortex of water near the pipe outlet 11b to adjust the pressure in the back pressure chamber 10. An adjustment mechanism 12 is provided. Therefore, according to the present embodiment, as in the first embodiment, it is possible to reduce the axial thrust force applied to the runner 4 without increasing the diameter or number of the balance pipes 11.

  Although several embodiments have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. The novel machine described herein can be implemented in a variety of other forms. In addition, various omissions, substitutions, and changes can be made to the machine configuration described in the present specification without departing from the scope of the invention. The appended claims and their equivalents are intended to include such forms and modifications as fall within the scope and spirit of the invention.

1: casing, 2: stay vane, 3: guide vane,
4: runner, 4a: blade, 4b: crown, 4c: band, 5: suction pipe,
6: main shaft, 7: generator, 8: upper cover, 9: lower cover, 10: back pressure chamber,
11: Balance pipe, 11a: Pipe inlet, 11b: Pipe outlet,
12: Pressure adjustment mechanism, 12a: Upstream portion, 12b: Downstream portion

Claims (7)

A runner that converts the energy of water flowing from the casing into rotational energy;
A main shaft that transmits the rotational energy of the runner to a generator;
A suction pipe into which the water that has driven the runner flows;
A balance pipe having a first opening opened in a back pressure chamber adjacent to the runner, and a second opening opened in the suction pipe;
A pressure adjusting mechanism provided in the vicinity of the second opening in the suction pipe, for adjusting the pressure in the back pressure chamber by generating a vortex of the water in the vicinity of the second opening;
With hydraulic machine.   The hydraulic machine according to claim 1, wherein the pressure adjustment mechanism is a protrusion protruding from an inner wall surface of the suction pipe.   The hydraulic machine according to claim 1, wherein the pressure adjustment mechanism is disposed on the upstream side of the second opening.   The hydraulic machine according to claim 3, wherein the pressure adjustment mechanism has a curved shape along the second opening.   The hydraulic machine according to claim 1, wherein the pressure adjustment mechanism has a tubular shape surrounding the second opening.   The hydraulic machine according to claim 1, wherein the pressure adjustment mechanism is rotatable in a circumferential direction of the second opening.   The hydraulic machine according to any one of claims 1 to 6, wherein the pressure adjusting mechanism can be expanded and contracted so that a length of the main shaft in a direction perpendicular to a rotation axis is changed.

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