JP6805298B1 - Small windmill device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a small wind turbine device having an appropriate peripheral speed ratio and high efficiency according to an installation environment. A small wind turbine device is fixed to a rotation center and has a large-diameter propeller having a plurality of main blades, and is fixed to the rotation center at a position on the wind side of the large-diameter propeller and has a plurality of sub-blades. A small-diameter propeller is provided, and the diameter of the small-diameter propeller is in the range of 0.2 times or more and less than 1.0 times the diameter of the large-diameter propeller. [Selection diagram] Fig. 1

Description

The present invention relates to a small wind turbine device including a large diameter propeller and a small diameter propeller.

As a technique related to a conventional wind turbine device for a generator, there is a wind turbine rotor including a hub, a spinner, and at least two main blades (see, for example, Patent Document 1). In the wind turbine rotor according to Patent Document 1, at least one auxiliary blade is provided so as to cover at least a part of the region between the blade roots of the two adjacent main blades.

Such sub-blades extend radially outward from the hub or spinner and have a wingspan shorter than that of the main blade. Further, the cord length of the sub-blade decreases monotonically from the blade side to the splash tip side.

Further, the sub-blade according to Patent Document 1 has the relationship of the following equation (1).
Copt-Cmain ≤ Cs ≤ 0.5 Copt (1)

Here, each of Copt, Cmine, and Cs in the above equation (1) means the following contents.
Copt: Optimal cord length of the main blade at the radial position r of the wind turbine rotor corresponding to the blade length direction position x Cmain: Cord length of the main blade at the radial position r Cs: Cord length

The optimum cord length Copt of the main blade is represented by the following equation (2).

Here, the "code length" and the "optimal code length" are defined as follows.
Cord length: The length of the cord (chord line) connecting the front edge and the trailing edge in the airfoil of the main blade.
Optimal cord length: A cord length defined by the above equation (2) according to each radius medical position r.

As a result, the wind turbine rotor according to Patent Document 1 can improve the aerodynamic performance in the inner section of the wind turbine rotor as a whole, and can effectively improve the blade efficiency of the wind turbine rotor.

JP-A-2015-86822

However, the prior art has the following problems. In general, a large wind turbine has a large propeller diameter of several tens of meters. Therefore, due to structural restrictions such as strength, the cord length of the main blade must be smaller than the optimum cord length. Therefore, in order to make up for the drawback that the cord length of the main blade becomes smaller than the optimum cord length, a sub blade is provided to bring the cord length closer to the optimum cord length.

Further, the blade shape of the wind turbine rotor according to Patent Document 1 of a large wind turbine is of a type in which both the main blade and the sub blade have a relatively high peripheral speed ratio and exhibit performance at a certain high rotation speed. Therefore, the blade of the wind turbine rotor according to Patent Document 1 is not a blade that can generate a large torque at low wind speed and low rotation speed and can greatly improve the cut-in wind speed.

On the other hand, depending on the installation environment, it is required to generate a desired torque and obtain an appropriate amount of power generation at low wind speed and low rotation speed. In particular, in a small wind turbine device having an output of 20 kW or less and a propeller diameter of 16 m or less, or a micro wind turbine device having an output of 1 kW or less and a propeller diameter of 2 m or less among small wind turbines, the above-mentioned appropriate power generation amount can be obtained. It is more demanding to get.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a small wind turbine device having an appropriate peripheral speed ratio and high efficiency according to an installation environment.

The small windmill device according to the present invention has a large-diameter propeller fixed to the rotation center portion and having a plurality of main blades, and a large-diameter propeller fixed to the rotation center portion at a position on the wind side of the large-diameter propeller and having a plurality of auxiliary blades. A small windmill device equipped with a small-diameter propeller, combining a large-diameter propeller fixed to the center of rotation and a small-diameter propeller, and configured as a hybrid propeller in which the large-diameter propeller and the small-diameter propeller rotate in the same direction at the same rotation speed. The diameter of the large-diameter propeller is 7 m or less, the diameter of the small-diameter propeller is in the range of 0.2 times or more and less than 1.0 times the diameter of the large-diameter propeller, and the small-diameter propeller is the center of rotation. The peripheral speed ratio as a hybrid propeller can be changed according to the installation environment by changing the diameter of the small-diameter propeller having a removable structure to the portion and having a removable structure.

According to the small wind turbine device according to the present invention, it is possible to obtain a small wind turbine device having an appropriate peripheral speed ratio and high efficiency according to the installation environment.

It is a front view which shows the small wind turbine apparatus which concerns on Embodiment 1 of this invention. It is a side view which shows the small wind turbine apparatus of FIG. 1 which concerns on Embodiment 1 of this invention. It is a figure which showed the rotation speed-torque characteristic at the time of using the hybrid propeller in Embodiment 1 of this invention. It is a figure which showed the relationship between the distance from the rotation center to the tip of a blade, and the cord length about four kinds of propeller shapes in the small wind turbine apparatus which concerns on Embodiment 1 of this invention. It is a figure which showed the relationship between the torque at the cut-in wind speed, and D2 / D1 in the small wind turbine apparatus which concerns on Embodiment 1 of this invention. It is a figure which showed the rotation speed-torque characteristic at the time of using the hybrid propeller in Embodiment 3 of this invention.

In the present invention, among the wind turbine devices, a small wind turbine device having an output of 50 kW or less and a propeller diameter of 7 m or less is targeted. Since the blades of the small wind turbine device do not receive as much force as the large wind turbine device, the cord length of the main blade can be designed close to the optimum value, and the peripheral speed ratio of the main blade can be designed high. In this case, the sum of the cord length of the secondary blade and the cord length of the main blade is longer than the optimum cord length of the main blade.

Therefore, in the small wind turbine device according to the present invention, the peripheral speed ratio of the main blade is designed to be high, and the peripheral speed ratio is increased according to the installation environment by installing the sub blade and partially lengthening the cord length. The technical feature is that it can be lowered. As a result, a wind turbine having an optimum peripheral speed ratio according to the installation environment can be easily realized without the trouble of redesigning the blade shape by simply changing the blade length of the similar shape. Therefore, a specific embodiment of the small wind turbine device according to the present invention will be described in detail with reference to the drawings.

Embodiment 1.
FIG. 1 is a front view showing a small wind turbine device according to a first embodiment of the present invention. Further, FIG. 2 is a side view showing the small wind turbine device of FIG. 1 according to the first embodiment of the present invention.

Small wind turbine devices for generators convert the energy of fluid flow into rotational energy. Examples of the fluid include air and water. The small wind turbine device for a generator includes a large-diameter propeller rotatably provided and a small-diameter propeller 2 installed on the upstream side of the large-diameter propeller 1. The large-diameter propeller 1 and the small-diameter propeller 2 are connected to a rotating shaft of a generator (not shown).

The large-diameter propeller 1 has a cylindrical rotation center portion 3 and a plurality of main blades 1a provided in the rotation center portion 3. In the following description, the radial direction is the radial direction of the rotation center portion 3. Further, the circumferential direction is the circumferential direction with respect to the rotation center portion 3. Further, the axial direction is the axial direction with respect to the rotation center portion 3.

The main blade 1a is fixed to the rotation center portion 3 so as to extend radially outward from the rotation center portion 3. In FIG. 1, three main blades 1a are arranged side by side at equal intervals in the circumferential direction. Further, each of the three main blades 1a has a length from the rotation center portion 3 to the tip in the radial direction of D1 as shown in FIG. In the following description, D1 will be referred to as the diameter D1 of the large-diameter propeller 1. Here, in the present invention, a propeller having a diameter of 7 m or less is defined as a small wind turbine device, and the diameter D1 is 3.5 m or less.

The large-diameter propeller 1 having such a configuration rotates in the circumferential direction. The rotation of the large-diameter propeller 1 causes the rotation shaft of the generator to rotate. The rotation axis of the generator is arranged so as to extend in the horizontal direction. In other words, the generator used in the small wind turbine device is configured as a horizontal axis generator.

On the other hand, the small-diameter propeller 2 has a cylindrical rotation center portion 3 and a plurality of auxiliary blades 2a provided in the rotation center portion 3, similarly to the large-diameter propeller 1. The small-diameter propeller 2 is fixed to the rotation center 3 so as to extend radially outward from the rotation center 3 and at a position on the windward side of the large-diameter propeller. In FIG. 1, three auxiliary blades 2a are arranged side by side at equal intervals in the circumferential direction.

Further, each of the three auxiliary blades 2a has a length from the rotation center portion 3 to the tip in the radial direction of D2 as shown in FIG. In the following description, D2 will be referred to as the diameter D2 of the small diameter propeller 2.

And the diameter D1 and the diameter D2 are
D1> D2
It is a relationship of. That is, the diameter of the large-diameter propeller 1 is configured to be larger than the diameter of the small-diameter propeller 2. Here, D2 / D1, which is the ratio of the diameter D2 to the diameter D1, is equivalent to the ratio of the diameter of the small diameter propeller 2 to the diameter of the large diameter propeller 1.

Further, the small-diameter propeller 2 has a structure that can be attached to and detached from the cylindrical rotation center portion 3, and can be relatively easily attached to and detached from the small-diameter propeller having a different shape of the auxiliary blade 2a depending on the installation environment and the like. It has a possible structure. That is, the small-diameter propeller 2 has a configuration in which it can be replaced with another propeller having a different diameter depending on the installation environment.

The large-diameter propeller 1 and the small-diameter propeller 2 can take out the output most efficiently when rotating at the peripheral speed ratio of each propeller. The peripheral speed ratio is shown in the following equation (3).
Peripheral speed ratio = Vr / Vf (3)
However, Vf: wind speed (m / s)
Vr: Peripheral speed (m / s) Movement speed of the outermost circumference of the propeller

The peripheral speed ratio varies depending on the shape of the propeller and the number of blades. In general, the peripheral speed ratio of a blade that is thin and has a small wind receiving area tends to be large, and conversely, the peripheral speed ratio of a blade that is thick and has a large wind receiving area tends to be small.

Taking FIG. 1 as an example, the large-diameter propeller 1 has a peripheral speed ratio of about 4.5, and the small-diameter propeller 2 has a peripheral speed ratio of about 2.

When a hybrid propeller that combines a large-diameter propeller 1 and a small-diameter propeller 2 as shown in FIGS. 1 and 2 is used, the rotation speed-torque characteristic indicating a change in torque with respect to the rotation speed depending on the value of D2 / D1. Is different.

FIG. 3 is a diagram showing the rotation speed-torque characteristics when the hybrid propeller according to the first embodiment of the present invention is used. In the characteristics shown in FIG. 3, the horizontal axis is the rotation speed (rpm) and the vertical axis is the torque (Nm). In FIG. 3, as D2 / D1, a comparison of the rotation speed-torque characteristics by a propeller having the following three kinds of values is shown.
Case 1: D2 / D1 = 0 (corresponding to the case where there is no small diameter propeller 2)
Case 2: D2 / D1 = 0.47
Case 3: D2 / D1 = 0.59

As shown in FIG. 3, when the number of rotations indicating the peak of torque is compared, the highest value is shown in case 1 (D2 / D1 = 0) in which there is no small-diameter propeller 2 and only the large-diameter propeller 1 is present. It can be seen that the lowest value is shown when D2 / D1 = 0.59). In other words, the larger the diameter D2 of the small-diameter propeller 2, the lower the peripheral speed ratio, and the propeller becomes compatible with low rotation. On the other hand, the smaller the diameter D2, the higher the peripheral speed ratio, and the propeller supports high rotation.

By simply changing the diameter D2 of the small-diameter propeller 2 in this way, the peripheral speed ratio as a hybrid propeller can be changed. Therefore, by using a small-diameter propeller 2 having a diameter D2 of an appropriate size according to the wind conditions of the installation environment, a hybrid propeller with an appropriate peripheral speed ratio and high efficiency can be realized.

For example, when a hybrid propeller is installed in a residential area where the wind is weak, a small-diameter propeller 2 having an appropriate size can be used so that the propeller can obtain high torque even at a low wind speed and has a low peripheral speed ratio. Further, when the hybrid propeller is installed in a place with a relatively strong wind such as an urban area, a small-diameter propeller 2 having an appropriate size can be used so as to be a propeller that supports high rotation and has a high peripheral speed ratio.

Also, in residential areas, wind noise at high speeds can be a problem. For such a problem, it is conceivable to use a small diameter propeller 2 having a relatively large diameter D2. By adopting such a small-diameter propeller 2, the peripheral speed ratio can be lowered and power generation can be performed at a low rotation speed, so that a noise reduction effect can be expected.

Further, by lowering the peripheral speed ratio, the torque at low rotation speed increases. Therefore, for example, even when the hybrid propeller is used as a monument to be aware of the environmental resistance in a park or the like, the rotation can be started by a breeze. As a result, environmental resistance consciousness can be effectively given.

Further, in the small wind turbine device according to the first embodiment, the cord length of the main blade 1a can be designed close to the value of the optimum cord length, and the peripheral speed ratio of the main blade can be designed to be high. In this case, the sum of the cord length of the sub blade 2a and the cord length of the main blade 1a is longer than the optimum cord length of the main blade 1a.

That is, in the small wind turbine device according to the first embodiment, the peripheral speed ratio of the main blade 1a is designed to be high, and then the auxiliary blade 2a having a desired shape is attached to partially lengthen the cord length. The technical feature is that the speed ratio can be lowered.

As a result, it is possible to realize a small wind turbine device capable of obtaining an optimum peripheral speed ratio according to the installation environment by replacing it with a small-diameter propeller 2 having a sub-blade 2a having a desired shape according to the installation environment. In particular, if a plurality of auxiliary blades 2a having similar shapes are prepared, the optimum peripheral speed ratio can be obtained according to the installation environment by selecting an appropriate auxiliary blade 2a from them. The device can be realized. Therefore, the optimum wind turbine shape can be easily realized without the trouble of redesigning the blade shape.

FIG. 4 is a diagram showing the relationship between the distance from the center of rotation to the tip of the blade and the cord length with respect to four types of propeller shapes in the small wind turbine device according to the first embodiment of the present invention. In FIG. 4, four types of propeller shapes of the following patterns 1 to 4 are illustrated.

Pattern 1: A small wind turbine device composed of only a large-diameter propeller 1 designed so that the main blade 1a has an optimum cord length.
Pattern 2: A small wind turbine device composed of only a large-diameter propeller 1 having a main blade 1a that is not the optimum cord length.
Pattern 3: A small wind turbine device configured by combining a large-diameter propeller 1 having a main blade 1a having an optimum cord length and a small-diameter propeller 2 having a sub-blade 2a having a relationship of D2 / D1 = 0.47. ..
Pattern 4: Small wind turbine device configured by combining a large-diameter propeller 1 having a main blade 1a having an optimum cord length and a small-diameter propeller 2 having a sub-blade 2a having a relationship of D2 / D1 = 0.59. ..

As shown in pattern 3 and pattern 4, it is possible to partially lengthen the cord length by designing the main blade 1a to have a high peripheral speed ratio and then attaching the sub blade 2a having a desired shape. Become. Then, by partially increasing the cord length, the peripheral speed ratio can be lowered to a desired value.

FIG. 5 is a diagram showing the relationship between the torque at the cut-in wind speed and D2 / D1 in the small wind turbine device according to the first embodiment of the present invention. As is clear from FIG. 5, as the value of D2 / D1 is increased, the peripheral speed ratio can be lowered and the torque at the cut-in wind speed can be increased.

Further, as shown in FIG. 5, in the range where the value of D2 / D1 is 0.2 or less, the torque at the cut-in wind speed hardly changes. Therefore, it is practical to set the value of D2 / D1 to at least 0.2 or more.

As described above, according to the first embodiment, a small wind turbine device having an appropriate peripheral speed ratio and high efficiency is realized by replacing the propeller with a small diameter propeller of an appropriate size according to each installation environment. be able to. The appropriate size means that the diameter of the small-diameter propeller is designed within a range of 0.2 times or more and less than 1.0 times the diameter of the large-diameter propeller.

In particular, by designing the cord length of the main blade as the optimum cord length and combining it with a small-diameter propeller that has an appropriate size auxiliary blade, it is easy to create a small wind turbine device that can achieve a propeller peripheral speed ratio suitable for the installation environment. Obtainable.

Embodiment 2.
In the second embodiment, the verification result regarding the performance of the small wind turbine device due to the difference in D2 / D1 which is the ratio between the diameter D1 of the large diameter propeller 1 and the diameter D2 of the small diameter propeller 2 will be described in more detail.

As described in the first embodiment, the characteristics of the hybrid propeller are changed as shown in FIG. 3 by changing the value of the ratio D2 / D1.

In FIG. 3, the characteristics when D2 / D1 = 0 (that is, when there is no small-diameter propeller 2 and only the large-diameter propeller 1) in case 1 and the characteristics when D2 / D1 = 0.47 in case 2 It can be seen that there is the following tendency when compared with.
-At around 1000 rpm, the torque is greatly improved in the case 2 as compared with the case 1.
-Furthermore, up to around 5500 rpm, the case 2 can generate a larger torque than the case 1.
-In addition, even at a rotation speed of 5500 rpm or more, the torque due to the case 2 is not significantly reduced as compared with the case 1.

On the other hand, when the characteristics of the case 3 in which the diameter D2 of the small-diameter propeller is further larger than that of the case 2 and the characteristics of the case 1 are compared, it can be seen that there are the following tendencies.
-At low rpm, the torque of Case 3 is higher than that of Case 1.
-At high rpm of 4000 rpm or more, it can be seen that the torque down of the case 3 is larger than that of the case 1, and the performance is deteriorated by the small diameter propeller 2.

As a result of detailed examination of the ratio D2 / D1 including cases other than case 2 and case 3, the following tendency was confirmed.
When D2 / D1 was 0.5 or less, the same tendency as in the case of D2 / D1 = 0.47 in Case 2 was confirmed.
-When D2 / D1 was larger than 0.5, it was confirmed that there was a tendency similar to that of D2 / D1 = 0.59 in Case 3.

As described above, according to the second embodiment, by applying a small-diameter propeller having a ratio D2 / D1 of 0.5 or less, the torque at low rotation speed can be improved and at high rotation speed. It is possible to suppress the decrease in torque as much as possible. As a result, by replacing the propeller with a small-diameter propeller 2 having a size such that the ratio D2 / D1 is 0.5 or less, a propeller with high efficiency and good characteristics can be realized. Therefore, according to the second embodiment, the size of the small-diameter propeller can be adjusted so that the peripheral speed ratio is adjusted to the wind conditions and environment of the installation environment, and the small wind turbine is easily suitable for the installation environment. The device can be supplied.

Embodiment 3.
In the third embodiment, the rotation speed-torque characteristic when the small-diameter propeller 2 having a ratio D2 / D1 having a larger value than that in the case 3 is used will be described.

FIG. 6 is a diagram showing the rotation speed-torque characteristics when the hybrid propeller according to the third embodiment of the present invention is used. In the characteristics shown in FIG. 6, the horizontal axis is the rotation speed (rpm) and the vertical axis is the torque (Nm). FIG. 6 shows a comparison of rotation speed-torque characteristics by a propeller having the following two values as D2 / D1.
Case 1: D2 / D1 = 0 (corresponding to the case where there is no small diameter propeller 2)
Case 4: D2 / D1 = 0.71

As in case 4 D2 / D1 = 0.71, the peripheral speed ratio is further lower than that in case 3 D2 / D1 = 0.59, so that the torque at low rotation is further increased. As a result, the rotation start wind speed of the propeller and the cut-in wind speed for starting power generation can be significantly reduced.

Further, on the high rotation side, in the case of the case 4, the torque drop becomes very large, and in the case of FIG. 6, at the rotation speed of 5500 rpm or more, as compared with the case of the case 1 having only the large diameter propeller 1, The torque is lower. This makes it difficult for the propeller to rotate at high speed. Therefore, rotation can be suppressed in a high rotation range, noise such as wind noise can be suppressed, and the effect of suppressing damage to the blade due to high rotation can be obtained.

When the ratio D2 / D1 was set to 0.7 or more, the same effect as when D2 / D1 = 0.71 could be verified.

As described above, according to the third embodiment, by applying a small-diameter propeller having a ratio D2 / D1 of 0.7 or more, the rotation start wind speed of the propeller and the cut-in wind speed for starting power generation are reduced. be able to. Further, in the high rotation range, rotation is suppressed, noise can be reduced, and damage to the blade can be prevented.

Embodiment 4.
In the fourth embodiment, the shape of the small diameter propeller 2 before and after the replacement will be described. When changing the diameter D2 of the small-diameter propeller 2, it is conceivable to design the small-diameter propeller 2 so that the shapes of the small-diameter propeller 2 have a similar shape relationship before and after replacement. By adopting such a similar shape, it becomes easy to design and manufacture a small-diameter propeller, and it is possible to shorten the design time and reduce the manufacturing cost.

Embodiment 5.
In the fifth embodiment, the shapes of the large-diameter propeller 1 and the small-diameter propeller 2 will be described. The number of main blades 1a constituting the large-diameter propeller 1 and the number of sub-blades 2a constituting the small-diameter propeller 2 should be the same, and the main blades 1a and the sub-blades 2a should be arranged at equal pitches. Can be considered.

By adopting such a shape, it is easy to balance the large-diameter propeller 1 and the small-diameter propeller 2, and the imbalance can be improved. Further, each sub-blade 2a of the small-diameter propeller 2 can be evenly arranged between the main blades 1a of the large-diameter propeller 1. Therefore, it is possible to realize a small wind turbine device that is easily affected by wind and has high efficiency.

1 Large diameter propeller, 1a main blade, 2 small diameter propeller, 2a sub blade, 3 rotation center.

Claims (4)

A large-diameter propeller fixed to the center of rotation and having multiple main blades,
A small-diameter propeller fixed to the rotation center portion at a position on the wind side of the large-diameter propeller and having a plurality of auxiliary blades is provided, and the large-diameter propeller fixed to the rotation center portion and the small-diameter propeller are combined. , A small wind turbine device configured as a hybrid propeller in which the large-diameter propeller and the small-diameter propeller rotate in the same direction at the same rotation speed.
The diameter of the large-diameter propeller is 7 m or less.
The diameter of the small-diameter propeller is in the range of 0.2 times or more and less than 1.0 times the diameter of the large-diameter propeller.
The small-diameter propeller has a structure that can be attached to and detached from the center of rotation.
A small wind turbine device that can change the peripheral speed ratio of the hybrid propeller according to the installation environment by changing the diameter of the small diameter propeller having a removable structure. The small wind turbine device according to claim 1, wherein the diameter of the small-diameter propeller is 0.5 times or less the diameter of the large-diameter propeller. The small wind turbine device according to claim 1, wherein the diameter of the small-diameter propeller is 0.7 times or more the diameter of the large-diameter propeller. The small wind turbine device according to any one of claims 1 to 3, wherein the plurality of main blades have an optimum cord length.

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