JP7514060B2 - Turbine blade mounting structure for hydroelectric power generating device and hydroelectric power generating device - Google Patents

Description

This invention relates to a turbine blade mounting structure for a hydroelectric power generation device that has turbine blades made of fiber-reinforced plastic material and is installed in a waterway to generate electricity using the power of water, and to the hydroelectric power generation device.

Hydroelectric power generation equipment includes turbine blades that convert the energy of water into rotational energy, and a generator that converts the rotational energy into electrical energy. In addition, if necessary, a speed increaser that increases the rotation of the turbine blades and transmits it to the generator, a control device that controls the generator, etc. are also provided.

When the turbine blades of a small-output hydroelectric power generating device are made of fiber-reinforced plastic material and are attached to the turbine shaft, which serves as the input shaft of the gearbox, the turbine blade attachment structure shown in Figure 10 has been used in the past. In this turbine blade attachment structure, first, both sides of the hub 10 of the turbine blade 1 are sandwiched between a pair of flange members 51, 52, and the pair of flange members 51, 52 and the hub 10 are fastened and fixed with bolts 53. Then, the assembly consisting of the turbine blade 1 and the pair of flange members 51, 52 is attached to the turbine shaft 20 at the flange members 51, 52 so that it cannot move axially or rotate. When the turbine blade 1 rotates under the force of the water, the rotational torque is transmitted to the flange members 51, 52 by frictional force, causing the turbine shaft 20 to rotate.

Patent Document 1 relates to a vertical axis hydroelectric power generation device, and describes how the vertical rotating shaft and three blades are fastened together using bolts and nuts.

JP 2017-8927 A

In hydroelectric power generation equipment installed in a waterway, the turbine blades are subjected to various fluctuating loads from the flowing water. For example, they are subjected to fluctuating loads due to changes in the flow speed of the flowing water. Furthermore, if the turbine blades are propeller turbines with a rotation axis parallel to the water flow direction, when the water level in the waterway drops and the top of the turbine blades are above the water surface, as the turbine blades rotate, the radially extending blades of the turbine blades are repeatedly submerged in the water and then above the water, resulting in a large alternating load.

The water level in a canal may drop when there is little precipitation or when the water in the canal is used for irrigation. Also, during the rainy season or when heavy rain is expected due to a typhoon, the flow rate of the canal may be restricted to prevent overflow from the canal.

As shown in Figure 10, when the turbine blade 1 is subjected to a fluctuating load F1, the blade bends in the direction of the load, and the bending is transmitted from the base of the blade to the hub 10. Then, the hub 10, which is sandwiched between the flange members 51 and 52 on both sides, is continuously subjected to a compressive force F2 from both flange members 51 and 52. This causes creep deformation of the hub 10, narrowing the axial width, loosening the bolts 53 fastening the turbine blade 1 to the flange members 51 and 52, and reducing the tightening force.

Also, alternating loads can cause gaps to form between the hub 10 and the flange members 51, 52, or the gaps can close, causing fretting wear on the contact surfaces of the hub 10 with the flange members 51, 52. Compared to unsaturated polyester resins, resin materials of fiber-reinforced plastic materials, such as vinyl ester resins, are more water-resistant and are less susceptible to strength degradation even when they come into contact with water. On the other hand, the fiber material of fiber-reinforced plastic materials can be subject to strength degradation when they come into contact with water. Because the outer skin of the turbine blade is made of resin material, contact with water does not promote a decrease in strength, but when fretting wear occurs on the hub 10, the fiber material of the turbine blade comes into contact with water from that point, leading to a decrease in strength of the turbine blade 1.

By making the turbine blade 1 out of a metal material, creep deformation of the hub 10 can be prevented. However, if an attempt is made to ensure the same strength with a metal material as when fiber-reinforced plastic material is used, the weight of the turbine blade 1 will increase. This means that it is necessary to increase the rigidity of the gear that supports the turbine shaft 20, which increases costs.

It is also possible to make the turbine blades 1 out of a relatively lightweight aluminum material. However, because steel is mainly used for the turbine shaft 20 and the gearbox, if the turbine blades 1 were made of aluminum, the aluminum and steel materials, which are dissimilar metals, would be immersed in water, which could cause electrolytic corrosion. For this reason, it is difficult to use aluminum.

The object of this invention is to provide a turbine blade mounting structure for a hydroelectric power generation device that can prevent the strength reduction caused by creep deformation and fretting wear of the turbine blade hub due to the turbine blade made of fiber-reinforced plastic material being subjected to fluctuating loads from flowing water, and a hydroelectric power generation device.

The water turbine blade mounting structure of the hydroelectric power generation device of the present invention is a water turbine blade mounting structure for mounting the water turbine blade made of a fiber-reinforced plastic material and a generator that generates electricity by receiving the rotation of the water turbine blade, the water turbine blade being mounted so as to rotate integrally with the water turbine shaft,
The water turbine blade has a solid hub at the center, and the water turbine shaft is inserted into a through hole provided in the hub.
A pair of flange members are disposed on both side surfaces of the hub, and bolts are inserted through bolt holes provided in the hub and the pair of flange members, and the hub and the pair of flange members are fastened together by the bolts;
The pair of flange members are attached to the water turbine shaft,
The pair of flange members have the same thickness in the longitudinal direction of the bolt, and have the same contact area with the hub.
In this case, the magnitude of the compressive forces that the hub receives from the flange members on both sides can be made approximately the same, so that an equal frictional force acts between the hub and each flange member, providing a good balance.

In the present invention, it is preferable that a chamfer is provided on the edge of the contact surface of the flange member with the hub.
When the chamfered portion is provided, the edge load is reduced, and the occurrence of fretting wear can be prevented.

It is also preferable that a fastening force retaining member, whose length is shorter than the axial width of the hub and whose both ends abut against the pair of flange members when the bolt is fastened, is interposed between the inner peripheral surface of the bolt hole of the hub and the outer peripheral surface of the bolt.

According to this configuration, when the bolts fastening the hub and the pair of flange members are tightened, the hub elastically deforms and its axial width narrows, causing both ends of the clamping force retaining member to abut against the pair of flange members. In this state, when the turbine blade is subjected to a fluctuating load and a compressive force acts on the center of the turbine blade from the pair of flange members, the compressive force is received by the clamping force retaining member and no large compressive force is applied to the hub, preventing creep deformation of the hub. In this way, by preventing creep deformation of the hub, it is possible to prevent the bolts from loosening and avoid a decrease in the clamping force between the hub and the flange members.

In addition, because the fastening force between the hub and the flange member is secured, even if an alternating load is applied to the turbine blade, a gap will not form or close between the hub and the flange member, and fretting wear will not occur on the contact surface between the hub and the flange member. This prevents water from penetrating into the fiber-reinforced plastic material of the turbine blade, preventing a decrease in the strength of the turbine blade due to material deterioration of the fiber-reinforced plastic material.

The turbine blade mounting structure of the hydroelectric power generation device of this invention is suitable when the turbine blade is a propeller turbine with multiple blades. It is particularly suitable when the turbine blade of the propeller turbine has a rotation axis parallel to the water flow direction. In either case, the turbine blade is subjected to large fluctuating loads, so there is a great effect in adopting the turbine blade mounting structure of this invention.

The hydroelectric power generation device of this invention is a hydroelectric power generation device equipped with a water turbine blade made of fiber-reinforced plastic material and a generator that generates electricity by receiving the rotation of the water turbine blade, and the water turbine blade is attached so as to rotate integrally with the water turbine shaft by the water turbine blade mounting structure described in any one of claims 1 to 5.
With a hydroelectric power generation system of this configuration, the turbine blades made of fiber-reinforced plastic are subjected to fluctuating loads from flowing water, which prevents the hubs of the turbine blades from undergoing creep deformation or fretting wear, resulting in a decrease in strength. This makes the hydroelectric power generation system more durable, shortens the time the system is shut down for maintenance, and improves its operating rate.

The water turbine blade mounting structure of this invention is a water turbine blade mounting structure for a water turbine equipped with a water turbine blade made of fiber-reinforced plastic material and a generator that generates electricity by receiving the rotation of the water turbine blade, and the water turbine blade is mounted so that it rotates integrally with the water turbine shaft. The water turbine blade has a solid hub in the center, the water turbine shaft is inserted into a through hole provided in the hub, a pair of flange members are arranged on both sides of the hub, bolts are inserted through bolt holes provided in the hub and the pair of flange members, the hub and the pair of flange members are fastened by the bolts, the pair of flange members are attached to the water turbine shaft, and the pair of flange members have the same thickness in the longitudinal direction of the bolts and the same contact area with the hub, so that the water turbine blade is subjected to a fluctuating load from flowing water, and the strength reduction caused by creep deformation and fretting wear of the hub of the water turbine blade can be prevented.

The hydroelectric power generation device of this invention is equipped with turbine blades made of fiber-reinforced plastic material and a generator that generates electricity by receiving the rotation of the turbine blades. The turbine blades are attached to the turbine shaft so that they rotate as one unit due to the turbine blade mounting structure of this invention. This prevents the turbine blades, made of fiber-reinforced plastic material, from receiving fluctuating loads from flowing water, causing creep deformation and fretting wear in the turbine blade hub, which can cause a decrease in strength. This makes the hydroelectric power generation device more durable, reduces the time the device is shut down for maintenance, and improves its operating rate.

1 is a front view of a hydroelectric power generation device to which a water turbine blade mounting structure according to a first embodiment of the present invention is applied. FIG. FIG. 3 is a side view showing the main part of FIG. 2, with a portion shown in cross section. FIG. 4 is a partially enlarged view of FIG. 3 . 6A is an enlarged view of a portion VIIA in FIG. 4, and FIG. 6B is an enlarged view of a portion VIIB in FIG. FIG. 4 is a cross-sectional view showing a turbine blade mounting structure according to a second embodiment of the present invention. FIG. 4 is a cross-sectional view of a hub of a turbine blade and a fastening force retaining member. FIG. 11 is a cross-sectional view showing a water turbine blade mounting structure according to a third embodiment of the present invention. FIG. 11 is a cross-sectional view showing a water turbine blade mounting structure according to a fourth embodiment of the present invention. FIG. 1 is a cross-sectional view showing a conventional water turbine blade mounting structure.

[First embodiment]
<Hydroelectric power generation equipment>
1 and 2 are a front view and a side view of a hydroelectric power generation device to which the hydroelectric blade mounting structure according to the first embodiment is applied. This hydroelectric power generation device is installed in a waterway to generate electricity using the power of water, and includes a hydroelectric blade 1, a speed increaser 2, a generator 3, and a support device 4. In addition, a control device (not shown) for controlling the generator 3, etc. are provided.

The turbine blade 1 is a propeller turbine with multiple (e.g., five) blades 11 extending radially from the outer periphery of the hub 10 located in the center, and is arranged so that the axis of rotation O is parallel to the direction A of the water flow in the waterway. The tip of each blade 11 is inclined toward the upstream side. The hub 10 and the blades 11 are formed integrally. A spinner 12 is attached to the front of the hub 10 on the upstream side. The hub 10, blades 11, and spinner 12 are made of fiber-reinforced plastic material.

The speed-up gear 2 increases the rotation speed of the turbine blades 1. The turbine shaft 20, which serves as the input shaft of the speed-up gear 2, protrudes upstream from the speed-up gear 2, and the turbine blades 1 are fixed to the turbine shaft 20 so that they rotate together.

As shown in FIG. 3, the speed-up mechanism 21 of the speed-up gear 2 consists of a pair of bevel gears 22, 23 that mesh with each other. The input bevel gear 22 is attached to the water wheel shaft 20, and the output bevel gear 23 is attached to a rotation transmission shaft 24 that extends vertically. The rotation transmission shaft 24 is a shaft that transmits the rotational force increased by the speed-up gear 21 to the generator 3, and is provided inside the support 25. As shown in FIG. 2, the support 25 has an upper end fixed to the support device 4, and the speed-up gear 2 is supported at its lower end.

In FIG. 2, the generator 3 has a generator shaft 30 extending downward, which is connected to the rotation transmission shaft 24 via a rotary connector 31. As a result, the rotation of the turbine blades 1 is accelerated by the speed increaser 2 and transmitted to the generator 3, which generates electricity. The generator 3 is, for example, a three-phase AC generator.

As shown in Figures 1 and 2, the support device 4 has two beams 40 that are installed between the side walls 5 on both sides of the waterway, a stand 41 placed on these beams 40, two generator stands 42 installed on this stand 41, and a base plate 43 that is installed to connect the upper parts of these two generator stands 42. The generator 3 is placed between the stand 41 and the base plate 43 and is fixed to the base plate 43.

<Water turbine blade mounting structure>
The structure for mounting the water turbine blades 1 to the water turbine shaft 20 will be described.
As shown in Figure 3, the water turbine shaft 20 has a large diameter portion 20a that protrudes upstream of the gearbox 2 (left side in Figure 3), and a small diameter portion 20b that extends upstream from the tip of the large diameter portion 20a, and a male thread 20c is formed on the outer peripheral surface of the small diameter portion 20b except for the base end.

The turbine blade 1 has a pair of annular flange members 51, 52 fastened to both upstream and downstream side surfaces of a hub 10 by bolts 53. The hub 10 is cylindrical and solid, having a through hole 50 in the center.
The upstream flange member 51 has an inner diameter smaller than the through hole 50 of the hub 10 and can be fitted into the small diameter portion 20b of the water turbine shaft 20. The downstream flange member 52 has a cylindrical portion 54 whose inner circumferential surface can be fitted into the large diameter portion 20a of the water turbine shaft 20 and whose outer circumferential surface can be fitted into the through hole 50 of the hub 10.

As shown in FIG. 4, the bolt 53 is inserted through the bolt holes 10a, 51a, and 52a provided in the axial direction of the hub 10 of the turbine blade 1 and the pair of flange members 51 and 52. In this embodiment, the bolt hole 52a of the downstream flange member 52 is a threaded hole, and the threaded portion 53a of the bolt 53 inserted from the upstream side into the bolt holes 51a and 10a is screwed into the threaded bolt hole 52a, thereby fastening the turbine blade 1 to the pair of flange members 51 and 52. As another example, the turbine blade 1 may be fastened to the pair of flange members 51 and 52 by screwing a nut (not shown) into the threaded portion 53a of the bolt 53 that passes through the bolt hole 52a of the downstream flange member 52, instead of the threaded hole of the bolt hole 52a of the downstream flange member 52.

In this turbine blade mounting structure, a pair of flange members 51, 52 fastened to the hub 10 of the turbine blade 1 have the same thickness in the length direction of the bolt 53, i.e., the same thickness in the axial direction of the turbine blade 1, and have the same contact area with the hub 10. The flange members 51, 52 are flat and have a uniform thickness on the outer diameter side of the cylindrical portion 54 of the downstream flange member 52. In the illustrated example, the upstream flange member 51 has a uniform thickness from the outer diameter end to the inner diameter end. However, as shown in Figures 5(A) and 5(B), the edges of the contact surfaces of the flange members 51, 52 with the hub 10 are provided with chamfered portions 61, 62 having an arc-shaped cross section. The chamfered portions 61, 62 may have other cross-sectional shapes. For example, they may have a curved shape such as a quadratic curve. In some cases, they may have a straight cutout shape.

A method for mounting the water turbine blades 1 on the water turbine shaft 20 will be described.
First, as shown in Fig. 4, flange members 51, 52 are fastened to both sides of the hub 10 with bolts 53 in the bolt holes 10a of the hub 10 to form an assembly. This assembly is then attached to the water turbine shaft 20 with the water turbine shaft 20 inserted through the through hole 50 of the hub 10 as shown in Fig. 3.

Specifically, the upstream flange member 51 is fitted to the base end of the small diameter portion 20b of the waterwheel shaft 20, and the cylindrical portion 54 of the downstream flange member 52 is fitted to the large diameter portion 20a of the waterwheel shaft 20. The upstream flange member 51 is then abutted against the step surface 20d between the large diameter portion 20a and the small diameter portion 20b, and the upstream flange member 51 is attached to the waterwheel shaft 20 so as not to move axially with respect to the waterwheel shaft 20 by a nut 56 screwed onto the male thread 20c of the small diameter portion 20b. In addition, the downstream flange member 52 is attached to the waterwheel shaft 20 so as not to rotate by engaging a key 57 with a key groove provided in the large diameter portion 20a of the waterwheel shaft 20 and the cylindrical portion 54 of the downstream flange member 52.

<Function of turbine blade mounting structure>
In this way, if the pair of flange members 51, 52 have the same axial thickness and the same contact area with the hub 10, the magnitude of the compressive force that the hub 10 receives from the flange members 51, 52 on both sides can be made approximately the same, so that an even frictional force acts between the hub 10 and each flange member 51, 52, providing a good balance. As a result, even with a fluctuating load, one side of the flange members 51, 52 does not receive an excessively large compressive force, making it difficult for creep deformation to occur. In addition, if chamfers 61, 62 are provided on the edges of the contact surfaces of the flange members 51, 52 with the hub 10, the edge load is reduced, and fretting wear can be prevented.

Second Embodiment
6 shows a second embodiment of the water turbine blade mounting structure. The bolt hole 10a of the hub 10 has an inner diameter larger than the bolt holes 51a, 52a of the flange members 51, 52, and a fastening force retaining member 55 is interposed between the inner peripheral surface of the bolt hole 10a of the hub 10 and the outer peripheral surface of the bolt 53. The fastening force retaining member 55 is made of a material that is harder than the fiber-reinforced plastic material of the water turbine blade 1 and is resistant to rusting in water, such as a metal material such as stainless steel (SUS304). The fastening force retaining member 55 of this embodiment is cylindrical and fits into the inner periphery of the bolt hole 10a.

7, the length of the fastening force retaining member 55 is slightly shorter than the axial width of the hub 10. More specifically, the length of the fastening force retaining member 55 is determined as follows. That is, if the length of the fastening force retaining member 55 is l and the axial width of the hub 10 is L, then
l = L - dl (Equation 1)
Here, dl is the upper limit of the displacement of the elastic deformation of the hub 10. Note that, although the dimension of dl is exaggerated in Fig. 7, the actual dimension of dl is so small that it is difficult to visually recognize it.

The fastening force retaining member 55 may simply be fitted to the inner peripheral surface of the bolt hole 10a of the hub 10, or may be fixed with an adhesive. When the fastening force retaining member 55 is fixed with an adhesive, it is preferable to fix the fastening force retaining member 55 so that it is positioned in the center of the bolt hole 10a, as shown in FIG. 7.

When the bolts 53 fastening the hub 10 to the pair of flange members 51, 52 are tightened, the hub 10 elastically deforms and its axial width narrows, so that both ends of the clamping force retaining member 55 come into contact with the pair of flange members 51, 52. In this state, when the turbine blade 1 is subjected to a fluctuating load and a compressive force acts on the center of the turbine blade 1 from the pair of flange members 51, 52, the compressive force is received by the clamping force retaining member 55 and no large compressive force is applied to the hub 10, suppressing creep deformation of the hub 10. In this way, by suppressing creep deformation of the hub 10, loosening of the bolts 53 can be prevented, and a decrease in the clamping force between the hub 10 and the flange members 51, 52 can be avoided.

When the length l of the fastening force retaining member 55 is set to a length that satisfies formula 1, the hub 10 deforms to the upper limit of elastic deformation when the bolt 53 is fastened. This makes the fastening of the bolt 53 stronger, making it even more difficult for the bolt 53 to loosen.

The fastening force retaining member 55 does not necessarily have to be cylindrical in shape, as long as it has a shape and dimensions that can strengthen the fastening force of the bolt 53 by satisfying the dimensional relationship of Equation 1. For example, it may be a member whose cross-sectional shape is U-shaped or groove-shaped.

In addition, because the fastening force between the hub 10 and the flange members 51, 52 is secured, even if an alternating load acts on the turbine blade 1, a gap will not form or close between the hub 10 and the flange members 51, 52, and fretting wear will not occur on the contact surfaces of the hub 10 with the flange members 51, 52. This prevents water from penetrating into the fiber-reinforced plastic material of the turbine blade 1, preventing a decrease in strength due to material deterioration of the turbine blade 1.

When the fastening force retaining member 55 is fixed to the inner peripheral surface of the bolt hole 10a of the hub 10 with an adhesive, damage to the inner peripheral surface of the bolt hole 10a caused by movement of the fastening force retaining member 55 inside the bolt hole 10a is suppressed. This also suppresses the penetration of water from the inner peripheral surface of the bolt hole 10a into the fiber reinforced plastic material.
When the fastening force retaining member 55 is fixed with an adhesive, it is preferable to fix the fastening force retaining member 55 to the center of the bolt hole 10a as shown in Figure 7, because this ensures that the elastic deformation of the hub 10 due to the fastening of the bolt 53 occurs evenly on both sides in the axial direction.

As described above, water penetration into the fiber-reinforced plastic material of the turbine blade 1 is suppressed, so there is no need to use expensive fiber-reinforced plastic material with high water resistance. In addition, because the fastening force retaining member 55 is cylindrical, not only is the fastening force retaining member 55 itself easy to process, but the bolt holes 10a are also easy to process. This makes it possible to prevent a decrease in the strength of the turbine blade 1 at low cost.

In addition, by interposing a fastening force retaining member 55 between the inner circumferential surface of the bolt hole 10a of the hub 10 and the outer circumferential surface of the bolt 53, the bolt 53 does not come into contact with the inner circumferential surface of the bolt hole 10a. Therefore, even if the turbine blade 1 receives a fluctuating thrust load from the water, wear on the surface of the inner circumferential surface of the bolt hole 10a can be prevented. As a result, water penetration into the fiber-reinforced plastic material from which the turbine blade 1 is made is suppressed, and a decrease in strength due to material deterioration of the turbine blade 1 can be prevented.

[Third embodiment]
In the first embodiment (FIG. 4) and the second embodiment (FIG. 6), the threaded portion 53a of the bolt 53 does not axially overlap with the bolt hole 10a of the hub 10, but as in the third embodiment shown in FIG. 8, a portion of the threaded portion 53a of the bolt 53 may axially overlap with the bolt hole 10a of the hub 10. In this case, the threaded portion 53a of the bolt 53 screws into the entire axial area of the bolt hole 52a, which is a threaded hole, and a large fastening force can be obtained.

[Fourth embodiment]
However, if a part of the threaded portion 53a of the bolt 53 overlaps with the bolt hole 10a of the hub 10 in the axial direction as shown in FIG. 8, there is a concern that the threaded portion 53a will come into contact with the fastening force retaining member 55, causing wear of the fastening force retaining member 55. In order to prevent such wear of the fastening force retaining member 55, it is preferable to configure it as shown in FIG. 9. In the fourth embodiment shown in FIG. 9, a recess 58 having a circular cross section that expands to the outer periphery of the bolt hole 52a is provided on the axially inner side surface of the downstream flange member 52, and the upstream end of the fastening force retaining member 55 is fitted into this recess 58. The threaded portion 53a of the bolt 53 is screwed into the bolt hole 52a, which is a screw hole. The base end position of the threaded portion 53a is within the axial range of the recess 58 or the bolt hole 52a. In other words, the threaded portion 53a of the bolt 53 is located axially outboard of the turbine blade 1. As a result, a part of the threaded portion 53 of the bolt 53 does not come into contact with the fastening force retaining member 55, and wear of the fastening force retaining member 55 is reduced.

Each of the second to fourth embodiments is similar to the first embodiment except for the points specifically described.
In each of the above embodiments, the axial thickness of both flanges 51, 52 of the hub 10 is equal, but the two flanges 51, 52 do not necessarily have to be of equal thickness as long as the thicknesses of the axially opposing portions are the same.
The above-mentioned embodiments show the turbine blade mounting structure applied to a hydroelectric power generation device in which the turbine blade 1 is a propeller turbine and the rotation axis O of the turbine blade is parallel to the water flow direction, but the present invention can also be applied to a hydroelectric power generation device in which the rotation axis O of the turbine blade 1 is not parallel to the water flow direction. Also, the present invention can be applied to a hydroelectric power generation device in which the turbine blade 1 is not a propeller turbine.

The above describes the form for carrying out the present invention based on the examples, but the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

Reference Signs List 1... Turbine blade 3... Generator 10... Hub 10a, 51a, 52a... Bolt hole 11... Blade 20... Turbine shaft 50... Through hole 51, 52... Flange member 53... Bolt 55... Fastening force retaining member 61, 62... Chamfered portion O... Rotation axis

Claims (5)

A water turbine blade mounting structure for a hydroelectric power generation device including a water turbine blade made of a fiber-reinforced plastic material and a generator that generates electricity by receiving the rotation of the water turbine blade, the water turbine blade being mounted so as to rotate integrally with the water turbine shaft,
The water turbine blade has a solid hub at the center, and the water turbine shaft is inserted into a through hole provided in the hub.
A pair of flange members are disposed on both side surfaces of the hub, and bolts are inserted through bolt holes provided in the hub and the pair of flange members, and the hub and the pair of flange members are fastened together by the bolts;
The pair of flange members are attached to the water turbine shaft,
In the water turbine blade mounting structure, the pair of flange members have the same thickness in the longitudinal direction of the bolt and the same contact area with the hub,
A turbine blade mounting structure for a hydroelectric power generation unit, characterized in that a fastening force retaining member is interposed between the inner surface of the bolt hole in the hub and the outer surface of the bolt, the fastening force retaining member having a length shorter than the axial width of the hub and whose both ends abut against the pair of flange members when the bolt is tightened, and when the bolt fastening the hub and the pair of flange members is tightened, the hub elastically deforms and its axial width narrows, causing both ends of the fastening force retaining member to abut against the pair of flange members . 2. The turbine blade mounting structure for a hydroelectric generating device according to claim 1, wherein the fastening force retaining member is fixed to the inner peripheral surface of the bolt hole of the hub by an adhesive. The turbine blade mounting structure for a hydroelectric power generation device according to claim 1 or 2, wherein the turbine blade is a propeller turbine having multiple blades. The turbine blade mounting structure for a hydroelectric power generation device according to claim 3, in which the turbine blade of the propeller turbine has a rotation axis parallel to the water flow direction. A hydroelectric power generation system comprising a water turbine blade made of fiber-reinforced plastic material and a generator that generates electricity by receiving the rotation of the water turbine blade, wherein the water turbine blade is attached so as to rotate integrally with the water turbine shaft by the water turbine blade mounting structure according to any one of claims 1 to 4.

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