JP2000320442A - Axial flow water wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain performance lowering of a moving blade by the changes in the operation condition and obtain a high efficiency by a moving blade support shaft and supporting the angle rotatably by a main shaft (water wheel rotation shaft), at an axial flow water wheel. SOLUTION: This water wheel is provided with a casing 4, having a guide vane on its outer periphery and storing a main shaft 21 of the water wheel on its inside and a hub, on whose outer periphery a moving blade 2a is provided and in whose inside a moving blade drive mechanism in which the moving blade 2a is rotatingly driven around a support shaft 17 of this moving blade 2a is stored. In the axial flow water wheel for driving this moving blade drive mechanism by the axial direction drive of the main shaft 21, the moving blade drive mechanism is provided with a drive mechanism for driving the support shaft 17, so as to vary the angle made by the support shaft 17 and main shaft 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an axial flow turbine,
In particular, the present invention relates to an axial flow turbine in which a mounting angle of a moving blade with respect to a main shaft is variable.

[0002]

14 and 15 are views showing a conventional axial-flow turbine. FIG. 14 is a sectional view of the conventional axial-flow turbine.
FIG. 5 is a plan view of the impeller seen from the AA direction in FIG. In these figures, 1 is a hub, 2 is a moving blade constituting an impeller, and 3 is a runner cone. The hub 1 has a plurality of moving blades, and a drive mechanism for rotating the moving blades around a support shaft thereof is provided inside the hub. Reference numeral 4 denotes a main shaft of the axial flow turbine and a casing for accommodating a generator connected to the main shaft, 12 denotes a main shaft position of the axial flow turbine, and 13 denotes a casing 12
Is a stay vane attached to the casing 12, 15 is a water flow formed on the outer periphery of the casing of the axial flow turbine, and 16 is a shaft for mounting the casing in the flow passage.

[0003] Casing 4 of an axial flow turbine incorporating a generator
Is installed in a flow path by a shaft 16, and a stay vane 14 for rectifying a water flow and a guide vane 13 for adjusting a flow rate are arranged in the flow path.

[0004] The impeller of the water wheel is composed of a plurality of propeller-like moving blades, and the impeller rotates by obtaining lift from the energy of the water flow 15. The rotation of the impeller causes the hub 1 and the runner cone 3 to rotate about the main shaft of the water turbine, and a generator mounted on the main shaft generates electric power and supplies the electric power to the outside via a cable (not shown).

FIG. 16 is a view showing a cross section taken along the line BB of FIG. In the figure, 43 is the direction of flow, 44 is the blade cross section, and 45 is the chord. The chord 45 is defined as a straight line connecting the front end in the rotation direction and the rear end in the rotation direction in the blade cross-sectional shape. Angle 46 is the angle between flow direction 43 and chord 45. Blade 2 in water flow
Is determined by the angle 46 between the flow direction 43 and the chord 45. That is, in order for the moving blade to exhibit high performance as a whole, in each cross section of the moving blade, the angle 46 between the flow direction 43 and the chord 45 is a maximum lift generation angle determined by the cross-sectional shape. is necessary.

Therefore, under the operating conditions where the operating frequency is the highest, the overall shape of the moving blade is designed so that the maximum lift generating angle can be obtained for all the moving blade sections from the root of the moving blade to the tip of the moving blade. The maximum efficiency can be obtained as a whole.

However, in actual operation of the axial flow turbine, it is necessary to operate in an operating state different from the operating condition with the highest operation frequency due to a change in the water level of the dam and a change in the amount of water used. At this time, the direction of the flow changes due to a change in the water level of the dam, a change in the amount of water used, and the like. Therefore, the flow direction 43 and the chord 4 in each section of the rotor blade
The angle 46 formed by 5 deviates from the maximum lift generation angle, the lift generated on the rotor blades is reduced, and the efficiency of the axial flow turbine is reduced.

Japanese Patent Application Laid-Open No. 3-151570 discloses that a rotating blade of an axial flow turbine is rotated around a rotating blade support shaft,
It is disclosed that the decrease in the efficiency is suppressed by changing the angle at which the rotor blade is attached to the hub and adjusting the angle between the flow direction and the chord so as to approach the maximum lift generation angle.

[0009]

Problems to be Solved by the Invention
In the technique disclosed in Japanese Patent No. 570, the moving blade is rotated around its support axis, so that the entire moving blade from the root to the tip of the moving blade changes by the same angle.

On the other hand, when the water flow changes due to the change in the operation state, the flow direction fluctuates. The fluctuation of the flow that occurs at this time does not always fluctuate by the same angle from the root portion of the moving blade to the tip portion of the moving blade, but a difference occurs in the amount of fluctuation between the root portion and the tip portion. The corners are larger than those at the tip.

As described above, the angle at which the flow fluctuates between the root portion and the tip portion is not constant. Regarding the water flow, even if the moving blade is rotated by a fixed angle, not all the moving blade sections from the root of the moving blade to the tip of the moving blade can be adjusted to the maximum lift generation angle. Therefore, the efficiency of the moving blade is reduced in the blade section in which the angle between the flow direction and the chord of the moving blade deviates from the maximum lift generation angle, and high efficiency cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an axial flow turbine capable of suppressing a decrease in performance of a rotor blade due to a change in operating conditions and obtaining high efficiency in a wide operating range.

[0013]

The present invention employs the following means in order to solve the above-mentioned problems.

A casing having a guide vane on the outer periphery and accommodating a main shaft of a water turbine therein, and a moving blade driving mechanism having a moving blade on the outer periphery and internally rotating the moving blade around a support shaft of the moving blade. An axial flow turbine that drives the moving blade drive mechanism by axial driving of the main shaft, the moving blade drive mechanism variably drives the angle between the support shaft and the main shaft. A driving mechanism that performs the driving.

Further, in the axial flow turbine, the blade driving mechanism drives the support shaft at a constant angle between the support shaft and an axis orthogonal to the main shaft.

Further, in the above axial flow turbine, the hub is provided with a groove in which the support shaft slides.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram showing a rotating part of an axial flow turbine according to an embodiment of the present invention. In the figure, reference numeral 2a denotes a rotor blade whose support shaft is rotatable and movable, 5
Is the support shaft position of the moving blade before movement, 6 is the moving blade before movement, 7 is the supporting shaft position of the moving blade after movement, 8 is the moving blade after movement, 9 is the moving blade position before movement, and 10 is the moving blade position before movement. The blade position 11 after the movement is a groove provided in the hub 1. The hub 1 has a spherical shape, and a groove 11 for sliding a support shaft of a rotor blade is formed in a curved shape on the spherical hub.

The moving blade 2a is rotatably mounted around its support shaft position 5. Further, the rotor blade support shaft is movably mounted so that the angle between the blade and the main shaft position 12 of the axial flow turbine changes.

When the moving blade 2a moves along the groove 11, the moving blade rotates around the moving blade support axis simultaneously with the movement. Therefore, before and after the movement of the moving blade, both the angle of rotation of the moving blade support shaft and the angle between the moving blade support shaft and the main shaft of the axial flow turbine change. In the drawing, the same portions as those shown in FIG. 14 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 2 is a view showing a moving blade according to the present embodiment. FIG. 2 (a) is a plan view, and FIG. 2 (b) is a cross-sectional view at the root position of the moving blade. In the figure, reference numeral 17 denotes a support shaft of the moving blade 2a, 18 denotes a root position of the moving blade, and 19 denotes a tip position of the moving blade. During the movement of the moving blade, the moving blade rotates around the support shaft 17.

FIGS. 3 and 4 are diagrams showing a change in position due to the movement of the moving blade. FIG. 3 shows the moving blade position (small flow rate position) before the moving, and FIG. Flow position). In these figures, reference numeral 20 denotes the chord of the rotor blade. In the drawings, the same portions as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted.

As shown in the drawing, the moving blade 2a is moved to the position 9 before the movement.
When moving to the post-movement position 10, the blade support shaft 17 rotates, and the angle between the chord 20 and the main shaft position 12 changes. At the same time, the angle between the support shaft 17 and the main shaft position 12 also changes.

5 to 9 are views showing a rotating and moving mechanism of the moving blade, FIG. 5 is a longitudinal sectional view of the rotating and moving mechanism of the moving blade, FIG. 6 is a sectional view taken along the line CC of FIG. 5, and FIG. DD sectional view of FIG.
8 is a sectional view taken along line EE of FIG. 5, and FIG. 9 is a sectional view taken along line FF of FIG. In these figures, reference numeral 21 denotes a main shaft of the axial-flow water turbine. The hub 1 is attached to one end of the main shaft 21 and a generator (not shown) is attached to the other end. 22 is a bearing mounted on the inner cylinder of the hub 1, 23 is a fixed support shaft, and 24 is a hub 1
25 is an arm 39 of the fixed support shaft 23
Reference numeral 26 denotes a connecting shaft rotatably mounted on the connecting shaft 25, and a connecting crank fixed to the connecting shaft 25 and rotatably mounted on the drive arm 27. Reference numeral 27 denotes a drive arm formed at one end of the main shaft 21, reference numeral 28 denotes an inner cylinder of the hub 1, reference numeral 29 denotes a gear fixed to the moving blade support shaft 17, and the moving blade support shaft 17 is rotatably attached to the arm 39. Reference numeral 30 denotes a gear rotatably attached to the fixed shaft 23, and reference numeral 31 denotes a gear fixed to the connection shaft.

Reference numeral 32 denotes a hydraulic case.
Supports the main shaft 21 rotatably and slidably in the axial direction. The hydraulic case 32 supports the hub 1 rotatably and restrains the axial movement. 33 and 34 are spaces in the hydraulic case, 35 and 36 are oil supply ports for supplying hydraulic pressure to the spaces 33 and 34 in the hydraulic case, respectively, and 37 is a support disk formed on the main shaft. The main shaft 21 is provided with a filler port 35 or a filler port 36.
By supplying the oil pressure from the controller, the actuator can be driven in the vertical direction as shown by the arrow 38.

When the main shaft 21 is driven in the vertical direction, the connecting shaft 25 can be driven in the direction shown by the arrow 40 via the connecting crank 26. When the connection shaft 25 is driven in the direction indicated by the arrow 40, the bucket support shaft 22 can be driven in the direction indicated by the arrow 40 via the arm 39 of the fixed support shaft.

When the main shaft 21 is further driven in the vertical direction,
The connecting shaft 25 rotates in the direction indicated by the arrow 41. When the connection shaft 25 rotates in the direction indicated by the arrow 41, the rotation is fixed to the bucket support shaft 17 via the gear 31 fixed to the connection shaft 25 and the gear 30 rotatably mounted on the fixed support shaft 23. This is transmitted to the gear 29 to drive the moving blade 2a in the direction indicated by the arrow 42.

As described above, the moving blade 2a has its support shaft 17
Is attached to the arm 39 of the fixed support shaft 23, and the fixed support shaft 23 is fixed to the hub 1 by bearings 22 and 24, and the moving blade rotates around the fixed shaft 23 when the moving blade rotates.

On the other hand, the fixed support shaft 23 is connected to a main shaft arm 27 via a connecting shaft 25 and a connecting crank 26. The spindle 21 has a spindle arm 27 at the tip of the spindle and a support disk 37 at the center of the shaft. The support disk 37 is rotatably supported by a hydraulic case 32. Also, when the turbine is rotating,
The main shaft 21, the hub 1, the rotor blade 2a, and the rotor blade rotation moving mechanism rotate integrally.

As described above, in this embodiment, the rotating movement of the moving blade is performed by the vertical movement of the main shaft. The inside of the hydraulic case 32 supporting the main shaft is divided into two by a supporting disk of the main shaft. Upper and lower spaces 33
And 34 are filled with oil through oil filler ports 35 and 36, and the vertical movement of the main shaft is adjusted by hydraulic pressure supplied from oil filler ports 35 and 36.

Next, the relationship between the vertical movement of the main shaft and the rotational movement of the moving blade will be described with reference to FIGS.

The vertical movement 38 of the main shaft 21 generated by supplying hydraulic pressure to the hydraulic case 32 is transmitted as vertical movement of the main shaft arm 27, and further transmitted to the connection shaft 25 via the connection crank 26. Since the connecting shaft 25 is attached to the arm 39 of the fixed support shaft, the vertical movement of the main shaft arm 27 is converted into a rotational motion 39 of the connecting shaft 25 about the fixed shaft 23. Therefore, the support shaft 17 of the moving blade attached to the arm 39 of the fixed support shaft rotates around the fixed support shaft 23. As shown in FIG. 5, the rotating shaft support shaft 17 is mounted obliquely with respect to the fixed support shaft 23, so that the rotating blade support shaft 17 rotates around the fixed support shaft 23, and thus the rotating blade support shaft and the main shaft (water turbine) (Rotation axis) changes.

As described above, the vertical movement of the spindle arm 27 is converted into the rotational movement 39 of the connecting shaft 25 about the fixed shaft 23. At this time, the connecting shaft 25 to which the connecting crank 26 is fixed further rotates. This rotating motion is transmitted to a gear 29 fixed to the moving blade support shaft 17 via a gear 31 fixed to the connecting shaft 25 and a gear 30 rotatably mounted to the fixed supporting shaft 23, thereby driving the moving blade support shaft 17 to rotate. I do. The rotation amount of the rotor blade support shaft, that is, the rotation amount of the rotor blade 2a, can be adjusted by changing the gear ratio of each gear.

As described above, by moving the main shaft 21, not only the rotating blade 2a is driven to rotate around the moving blade support shaft 17, but also the moving blade support shaft 17 itself is connected to the main shaft (water turbine rotating shaft). It can be driven so that the angle formed changes.

Next, the effects of the present invention will be described with reference to FIGS.

In describing the effects of the present invention, first,
Consider two operating conditions with different flow rates. As a first operating condition, it is assumed that there is a large amount of water stored in the dam and a large flow rate that allows a large amount of water to flow, and as a second operating condition, the amount of water stored in the dam is small and a large amount of water is allowed to flow. Assume a condition of small flow that cannot be achieved. Then, it is assumed that the flow rate of the dam is relatively large throughout the year, and it is assumed that the rotor blade is designed to exhibit the maximum performance under the first operating condition.

FIG. 10 is a diagram showing the distribution of the angle between the flow and the chord under the first operating condition (large flow rate).
The vertical axis represents the angle between the chord and the flow, and the horizontal axis represents the sectional position of the moving blade. In the figure, a point 47 indicates the root of the bucket, and a point 48 indicates the tip of the bucket. A solid line 49 indicates the distribution of the angle between the flow of the moving blade and the chord according to the present embodiment, and a broken line 50 indicates the distribution of the angle between the flow generating the maximum lift and the chord. 51 is the angle between the chord and the flow at the root of the blade, and 52 is the angle between the chord and the flow at the tip of the blade. As shown in the figure, the moving blade according to the present embodiment is designed so as to exhibit the maximum performance under the first operating condition.

FIG. 11 is a diagram showing the distribution of the angle between the flow and the chord under the second operating condition (small flow rate). The vertical axis represents the angle between the chord and the flow, and the horizontal axis represents the sectional position of the moving blade. In the figure, a solid line 54 shows a rotor blade according to a conventional example, that is, a flow of a rotor blade that rotates and drives the rotor blade only around its support axis and a distribution of an angle formed by a chord, and a solid line 55 according to the present embodiment. The distribution of the angle between the flow of the moving blade and the chord is shown, and the broken line 50 shows the distribution of the angle between the flow generating the maximum lift and the chord.

FIG. 12 is a diagram showing the flow at the blade root and the blade cross section. In the figure, arrow 56 indicates the direction of flow under the first operating condition, and arrow 57 indicates the direction of flow under the second operating condition. Also, angles 51 and 58
Indicates the angle between the flow and the chord, respectively.

FIG. 13 is a diagram showing the flow at the blade tip and the blade cross section. In the figure, an arrow 60 indicates the flow direction under the first operating condition, and an arrow 61 indicates the flow direction under the second operating condition. Also, the angles 52, 62
Indicates the angle between the flow and the chord, respectively.

Under the second operating condition, the operation is performed with a reduced guide vane opening in order to operate with a reduced flow rate. For this reason, the angle of the flow flowing into the rotor blade arranged downstream of the guide vane changes. That is, the flow at the blade root changes from the arrow 56 direction to the arrow 57 direction.
On the other hand, the flow at the blade tip changes from the direction of arrow 60 to the direction of arrow 61. These changes in the flow indicate a state in which the flow rate is reduced only by the guide vanes without moving the rotor blades.

That is, the amount of change in the flow angle is different between the blade root portion and the blade tip portion, and is large at the blade root portion. On the other hand, as shown in the conventional example, when the moving blade is rotated around the moving blade support axis, the moving blade root and the moving blade tip change by the same angle. When the tip of the moving blade is adjusted to the angle at which the maximum performance is exhibited, a deviation angle indicated by an angle 53 remains at the root of the moving blade. That is, the shift angle causes performance degradation under the second operating condition. The deviation angle 53
Is the angle 58a in FIG. 12 and the angle 62 in FIG.
a.

In this embodiment, not only is the rotating blade 2a driven to rotate around the rotating blade support shaft 17, but also the angle formed by the rotating blade support shaft 17 itself with the main shaft (water turbine rotating shaft) changes. In addition to the uniform angle correction obtained by rotation around the support shaft, a new degree of freedom for tilting the blade support shaft is added to the angle correction that cannot be obtained by rotation around the support shaft. Is carried out to correct the deviation angle 53.

As a result, the flow of the moving blade and the distribution of the angle formed by the chord obtained by rotating the moving blade only around its support axis are shown in FIG. Curve 5 close to curve 50 showing the distribution of the angles made by the strings
Up to 5 can be corrected.

[0044]

As described above, according to the present invention, the moving blade is rotatable around its support shaft, and the moving blade support shaft variably moves the angle formed by the main shaft (water turbine rotating shaft). Since it is possible, it is possible to obtain an axial flow turbine that can suppress the performance deterioration of the rotor blade due to a change in operating conditions and can obtain high efficiency in a wide operating range.

[Brief description of the drawings]

FIG. 1 is a view showing a rotating part of an axial flow turbine according to an embodiment of the present invention.

FIG. 2 is a view showing a rotor blade of the axial flow turbine.

FIG. 3 is a diagram showing a change in position due to movement of a moving blade.

FIG. 4 is a diagram showing a change in position due to movement of a rotor blade.

FIG. 5 is a longitudinal sectional view of a rotating blade moving mechanism.

FIG. 6 is a sectional view taken along the line CC of FIG. 5;

FIG. 7 is a sectional view taken along line DD of FIG. 5;

FIG. 8 is a sectional view taken along the line EE of FIG. 5;

FIG. 9 is a sectional view taken along line FF of FIG. 5;

FIG. 10 is a diagram showing a distribution of an angle between a flow and a chord under a first operating condition.

FIG. 11 is a diagram showing a distribution of an angle between a flow and a chord under a second operating condition.

FIG. 12 is a diagram showing a flow at a blade root portion and a blade cross section.

FIG. 13 is a diagram showing the flow at the tip of the moving blade and the cross section of the blade.

FIG. 14 is a sectional view of a conventional axial flow turbine.

FIG. 15 is a plan view of a conventional impeller.

FIG. 16 is a sectional view of a conventional rotor blade.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hub 2, 2a Moving blade 3 Runner cone 4 Casing 5 Position of supporting shaft of moving blade before moving 6 Moving blade supporting shaft position before moving 8 Moving blade 9 after moving 9 Moving blade position before moving 10 Blade position after movement 11 Groove 12 Main shaft position 13 Guide vane 14 Stay vane 16 Stay 21 Main shaft 22, 24 Bearing 23 Fixed support shaft 25 Connection shaft 26 Connection crank 27 Drive arm 28 Hub inner cylinder 29, 20, 31 Gear 32 Hydraulic case 33, 34 Space of hydraulic case 35, 36 Filler port 37 Support disk 39 Arm of fixed support shaft

Claims (3)

[Claims] 1. A casing having a guide vane on an outer periphery thereof and accommodating a main shaft of a water turbine therein, and a rotor blade having a rotor blade on an outer periphery and rotatably driving the rotor blade around a support shaft of the rotor blade therein. An axial flow turbine that includes a hub that accommodates a driving mechanism, and drives the moving blade drive mechanism by driving the main shaft in an axial direction, wherein the moving blade drive mechanism varies an angle between the support shaft and the main shaft. An axial-flow water turbine comprising a driving mechanism for driving the waterwheel. 2. The axial-flow turbine according to claim 1, wherein the blade driving mechanism drives the support shaft at a constant angle between the support shaft and an axis orthogonal to the main shaft. 3. The axial-flow water turbine according to claim 1, wherein the hub has a groove in which the support shaft slides.