JP2001234843A - Water turbine moving blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water turbine moving blade capable of realizing high cavitation performance and a high work efficiency even under an operating condition having much water flow. SOLUTION: This water turbine moving blade which is provided with a hub 7 connected to a water turbine rotary shaft and a plurality of moving blades 6 which are disposed around the hub and which are attached extending to a radial direction on an outer periphery of the hub 7, the cross section of the blade along the water flow direction of the moving blade 6 is formed in a nearly S-shaped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine blade device, and more particularly to a turbine device in which the turbine blade is radially attached to the outer periphery of a rotating hub.

[0002]

2. Description of the Related Art A water turbine equipped with this type of water turbine moving blade device is:
As shown in FIGS. 3 and 4, an impeller, that is, a hub 7 having a moving blade 6 and a runner cone 8 is provided on the downstream side of a water turbine main body casing 10 containing a generator, and is rotated by a water flow 15. It is formed so that. A casing 10 of the water turbine main body is installed at a predetermined position in a flow path by a shaft 11, and a stay vane 12 for rectifying a flow of water and a guide vane 13 for adjusting a flow rate are provided in a flow path on the outer periphery of the casing. Is provided.

A plurality of blades 6 constituting an impeller are mounted with propeller-shaped blades mounted on the outer periphery of a hub in a radial direction, that is, in a radial direction.
It takes the energy of the wings as lift of the wings and converts it into rotational force of the impeller.

The hub 7, the rotor blades 6, and the runner cone 8 rotate around the turbine rotation shaft 14 due to the rotation force, and power is generated by a generator attached to the rotation shaft. Therefore, the power generation amount of this type of hydropower plant is largely influenced by the fluid performance of the rotor blades 6, and it is essential to generate as much lift as possible on the rotor blades in order to improve the power generation performance of the plant.

[0005] A typical shape of a moving blade is, as shown in a sectional shape in FIG. 5, an action using a chord 16 connecting a blade tip (leading edge) and a trailing end (trailing edge) as a reference line. It has a shape composed of a surface 17 and a reaction surface 18. The work volume of the blade is determined by the pressure difference of the fluid applied to each surface.

[0006] The greater the pressure difference between the working surface 17 and the reaction surface 18, the greater the amount of work of the wing. Therefore, the shape of the wing is designed and designed so that a large pressure difference can be obtained between the two surfaces. I have.

However, in a hydraulic machine, since the working fluid is water, when the pressure drops below the saturated vapor pressure of water, a cavitation phenomenon occurs in which bubbles are generated from that portion. When cavitation is generated from the wing surface, the efficiency of the wing is greatly reduced. Therefore, it is necessary to control the minimum pressure on the wing surface to a pressure at which cavitation does not occur. Control of the pressure distribution on the wing surface is also performed by manipulating the shape of the wing cross section.

[0008] Japanese Patent Application Laid-Open No. 3-151570 and Japanese Patent Application Laid-Open No. 53-85501, for example, relate to this type of turbine blade.

[0009]

Since a water turbine in a hydropower plant is operated under various operating conditions depending on the water level and flow rate of a dam, its moving blade is designed to have an optimum shape for the target plant conditions. Is required. But,
The mere use of the conventional wing having a simple wing cross-sectional shape does not always achieve the desired performance under the required operating conditions. In particular, under operating conditions where the flow rate is high, the pressure drop in the latter half of the blade tip tends to cause cavitation, which may result in a significant performance drop.

[0010] The present invention has been made in view of the above, and it is an object of the present invention to operate under a large flow rate of water, that is, under a large load on the blade tip side.
An object of the present invention is to provide a water turbine moving blade apparatus of this type capable of realizing high cavitation performance and high work efficiency.

[0011]

That is, the present invention comprises a hub connected to a rotating shaft of a water turbine, and a plurality of moving blades arranged around the hub, wherein the moving blade is provided on an outer periphery of the hub. In a water turbine moving blade device mounted so as to extend in a radial direction (radial direction), a blade shape of a cross section of the moving blade along a water flow direction is formed to be substantially S-shaped, thereby achieving an intended purpose. Things.

Further, the present invention includes a hub connected to a water turbine rotating shaft, and a plurality of moving blades arranged around the hub, wherein the moving blades are arranged radially (radially) on the outer periphery of the hub. In a water turbine moving blade device mounted so as to extend, a cross-sectional shape when a portion near a radially outer peripheral side of the moving blade is cut along a water flow direction is formed to be substantially S-shaped. .

[0013] In addition, a hub connected to the rotating shaft of the turbine and a plurality of moving blades arranged around the hub are provided, and the moving blades extend radially (radially) around the outer periphery of the hub. In the water turbine moving blade device attached, a cross-sectional shape when a portion near the trailing edge side of the moving blade is radially cross-sectionally formed is substantially S-shaped. In addition, the cross-sectional shape when the radially outer peripheral side portion of the moving blade is sectioned along the water flow direction is formed substantially in an S shape, and the trailing edge side near portion of the moving blade is radially sectioned. Has a substantially S-shaped cross section.

That is, in the water turbine moving blade device thus formed, since the blade shape of the cross section along the water flow direction of the moving blade is formed substantially in an S shape, the warpage in the front half of the blade is reduced. Larger, the warpage of the latter half of the wing is smaller, and therefore the pressure can be increased only in the latter half of the wing.Details will be described later, but the work of the whole wing can be increased compared to the conventional one, High efficiency can be achieved while preventing cavitation.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 shows a moving blade of the water turbine moving device, that is, a front view of a single moving blade. Bucket 6
Is attached to the hub 7 by a stem portion 5 attached to a portion of the side 4 on the hub side of the rotor blade. The flow of water from the dam flows from the side (front edge) 1 side of the blade tip to the side (rear edge) 2 side of the rear end.

This moving blade 6 is particularly formed as follows. That is, when a portion near the outer peripheral side (the side 3 on the blade tip side) in the radial direction (Y arrow direction) of the rotor blade 6 is sectioned along the water flow direction (X arrow direction), the cross-sectional shape is substantially S-shaped. Is formed. That is, as shown in FIG. 1B, the cross-sectional wing shape along the line AA in FIG. 1A is formed substantially in an S shape. In this case, the sectional shape of the vicinity of the inner peripheral side in the radial direction of the moving blade 6 may be of course an S-shape, but FIG.
As a result of the experiment, it was more effective to simply form a curved shape (warp shape) as described above, in other words, a U-shape.

As described above, the cross-sectional shape in the direction along the flow of water in the vicinity of the radial outer periphery of the rotor blade has an S-shape, and the normal warped shape diagram 1 extends from the side 4 on the hub side to the side 3 on the tip side. The shape changes smoothly from (b) to the S-shaped warp shape shown in FIG. 1 (c).

Next, the operation of the rotor blade thus formed will be described with reference to FIGS. 6 and 7 in comparison with a conventional blade. FIG. 6 shows a typical pressure distribution on the wing surface. The horizontal axis indicates the distance from the blade tip, and the vertical axis indicates the pressure value on the blade surface. Of the two curves in the graph, the distribution 20 with the higher value is the active surface side 17 of the wing.
Is a pressure distribution on the semi-working surface side 18. The area 22 of the region surrounded by the two curves represents the work done by the wing. A low pressure area 23 indicated by oblique lines is an area where cavitation occurs. When the pressure value 21 on the reaction surface decreases to this area, cavitation occurs from that part and the performance of the blade is greatly reduced.

When a rotor blade using only a normal warp shape is used, the cross section AA on the blade tip side depends on the operating conditions of the water turbine.
Is in a state as shown by a distribution 24 in FIG. Since cavitation occurs in the portion 25 where the pressure in the latter half of the blade has greatly decreased, the efficiency of the water turbine is greatly reduced when operating in this state. If this state can be predicted by a numerical experiment or the like at the design stage, a method conventionally used to avoid cavitation is shown in FIG.
The size of the warpage of the wing shape with the normal warpage shown in 28
Was to be changed to a shape having a small value of warpage 29 while keeping the blade cross-sectional shape similar, as shown in FIG.

By making such a change, the pressure on the blade surface rises, and as shown by the distribution 26 in FIG. 7, the minimum pressure on the reaction surface can be prevented from being applied to the cavitation generation region, and the latter half of the blade can be obtained. It is possible to suppress the occurrence of cavitation in the part. However, in this method, the pressure in the first half of the blade is increased, and the work performed by the blade, which is indicated by the pressure difference between the working surface and the reaction surface, is reduced, and the efficiency of the whole blade is reduced.

On the other hand, according to the wing shape of the present invention, as shown in FIG. 10, the warp 30 in the front half of the wing is not reduced from the warp 28 of the original shape and the warp in the rear half of the wing is reduced. 31 can be reduced, and the pressure can be increased only in the latter half of the wing. As a result, the pressure distribution becomes like the distribution 27 in FIG.
As a result, the work amount of the entire wing can be increased, and cavitation can be prevented and, at the same time, high efficiency can be realized.

Next, another embodiment of the present invention will be described with reference to FIG. In this case, the cross-sectional shape of the portion near the trailing edge side of the moving blade along the radial direction, that is, the cross section along the line CC near the trailing edge of the blade in the direction perpendicular to the flow of water in FIG. As shown in FIG. 2, the shape is formed substantially in an S shape.

Even in this configuration, the warp in the latter half of the blade is reduced, the pressure drop in the latter half of the blade tip can be locally suppressed, and the load becomes more severe in the latter half of the blade tip, so that a large flow rate operation is performed. Under the conditions, high cavitation performance and high efficiency can be simultaneously realized. In this case, of course, this shape alone may be used, but it is also possible to combine with the above-described embodiment.

In the above description, it is described that the cross-sectional shape of the rotor blade is substantially S-shaped. However, this is in the case of a certain rotational direction, and the reverse S-shaped when the rotational direction is reversed. Needless to say, the inverted S-shaped type is also described here as the S-shaped type.

As described above, according to the water turbine moving blade apparatus formed in this manner, the blade shape of the cross section of the moving blade 6 along the water flow direction or the vicinity of the trailing edge side of the moving blade 6 extends in the radial direction. The cross-sectional shape when cross-sectioned is formed in an almost S-shape, so that the warp of the rear half of the wing is reduced,
The pressure can be increased only in the second half of the wing, that is, by locally suppressing the pressure drop in the second half of the wing tip, high cavitation performance and high workability can be achieved under operating conditions where a large load is applied to the wing tip. Efficiency can be realized.

[0026]

As described above, according to the present invention, high cavitation performance and high work efficiency can be realized even under operating conditions where the amount of flowing water is large, that is, under operating conditions where a large load is applied to the tip side of the blade. This kind of water turbine bucket device capable of being obtained can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view and a sectional view of a main part of an embodiment of a water turbine moving blade apparatus according to the present invention.

FIG. 2 is a sectional view taken along line CC of FIG.

FIG. 3 is a side view showing a water turbine provided with a water turbine moving blade device.

FIG. 4 is a front view showing a water turbine provided with a water turbine bucket device.

FIG. 5 is a view showing a cross-sectional shape of a conventional moving blade.

FIG. 6 is a diagram showing a pressure distribution on a blade surface.

FIG. 7 is a diagram showing a pressure distribution with a high load in the latter half of the blade.

FIG. 8 is a view showing a cross-sectional shape of a conventional moving blade.

FIG. 9 is a diagram showing a cross-sectional shape of a conventional moving blade.

FIG. 10 is a diagram showing a cross-sectional shape of a bucket in the turbine bucket apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... The edge of the blade front end, 2 ... The edge of the blade rear end, 3 ... The edge on the blade tip side, 4 ... The edge on the blade hub side, 5 ... Stem, 6 ...
7 ... hub, 8 ... runner cone, 10 ... casing, 1
DESCRIPTION OF SYMBOLS 1 ... Shaft, 12 ... Stay vane, 13 ... Guide vane, 14 ... Water turbine center axis, 15 ... Water flow from dam 1
6 ... chord, 17 ... working surface, 18 ... reaction surface, 20 ... pressure on the working surface side, 21 ... pressure on the reaction surface side, 22 ... work done by the wing, 23 ... cavitation generation area, 25 ... reaction by the prior art Pressure distribution on the reaction surface, 26: Pressure distribution on the reaction surface after modification of the blade shape by the prior art, 27: Pressure distribution on the reaction surface using the present invention, 28: Cross-sectional shape of the blade by the conventional technology, 29: After modification by the conventional technology Wing cross-sectional shape, 30 ...
The wing cross-sectional shape using the present invention.

Claims (6)

[Claims] 1. A vehicle comprising: a hub connected to a rotating shaft of a water turbine; and a plurality of moving blades disposed around the hub.
In a water turbine moving blade device attached to an outer periphery of the hub in a radial direction (radial direction), a cross-sectional shape of the moving blade along a water flow direction is substantially S-shaped. Water turbine moving device. 2. A vehicle comprising: a hub connected to a rotating shaft of a water turbine; and a plurality of moving blades arranged around the hub.
In a water turbine moving blade device attached to the outer periphery of the hub in a radial direction (radially direction), a cross-sectional shape of a portion of the moving blade near a radial outer peripheral side along a water flow direction is substantially S. A water turbine bucket device characterized by being formed in a character shape. 3. A hub connected to a rotating shaft of a water turbine, and a plurality of moving blades disposed around the hub, wherein the moving blades are:
In a water turbine moving blade device attached to the outer periphery of the hub in a radial direction (radial direction), a cross-sectional shape of a portion near a trailing edge side of the moving blade along a radial direction is substantially S-shaped. A water turbine moving blade device characterized by being formed in. And a hub connected to the rotating shaft of the turbine and a plurality of moving blades disposed around the hub.
In a water turbine moving blade device attached to the outer periphery of the hub in a radial direction (radially direction), a cross-sectional shape of a portion of the moving blade near a radial outer peripheral side along a water flow direction is substantially S. A water turbine moving blade device, wherein the water turbine moving blade device has a substantially S-shaped cross-section when a portion near a trailing edge side of the moving blade is radially cross-sectioned. 5. A vehicle comprising: a hub connected to a rotating shaft of a water turbine; and a plurality of moving blades arranged around the hub, wherein the moving blade includes:
In a water turbine moving blade device attached to the outer periphery of the hub in a radial direction (radially direction), a cross-sectional shape of a portion of the moving blade near a radial outer peripheral side along a water flow direction is substantially S. A water turbine, wherein the water turbine is formed in a U-shape, and gradually changes toward the radially inner peripheral side of the moving blade, and is formed substantially U-shaped near a radially inner peripheral side of the moving blade. Moving blade device. 6. The water turbine moving blade apparatus according to claim 5, wherein the boundary of the change in the cross-sectional shape of the moving blade from the S-shape to the U-shape is on the outer peripheral side from the radial center of the moving blade.