JP2009180228A - Vertical axis type wind mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical axis type wind mill which can improve a power generation efficiency in a wide range of wind-speed zones by increasing the ratio of the chord length of a blade to its thickness and by providing a notch which is formed in a part of the blade in an optimal position. <P>SOLUTION: The vertical axis type wind mill is provided with a plurality of blades which are placed inside of the surface orthogonal to a vertical rotary shaft about the vertical rotary shaft at equal-angle intervals. The outer surface of a wing is bent outside by a large amount compared to the inner surface of the wing, and the blade is formed by a streamlined asymmetrical profile having a lift coefficient of 1.0 or more. Then the notch part is formed on the inner surface of the wing of the blade by making notches from the starting point, which is a predetermined position, to the rear edge. The thickness of the blade is made 22% to 30% of the chord length of the blade, and the predetermined position is set in a more backward location than a location which is 45% of the chord length of the blade from the front edge, and in a more forward location than a location which is 65% of the chord length of the blade. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vertical axis type windmill used for wind power generation and the like, and more particularly to a vertical axis type windmill whose blade shape is improved so as to improve the power generation efficiency of the windmill.

  In general, wind turbines for wind power generation include a horizontal axis type wind turbine (propeller type wind turbine) in which the rotation axis is horizontal (parallel) to the wind direction, and the rotation axis is perpendicular to the wind direction. A vertical axis windmill is known.

  Of these, vertical axis windmills, such as the Savonius type and paddle type, have the drag that causes the windmill to rotate by the Savonius effect, where the drag acting on the part (blade) that generates the aerodynamic force of the windmill is the main rotational force of the windmill. There are known types such as a die and a lift type that rotates a windmill by a gyromill effect in which a rotational direction component of lift acting on a blade is a main rotational force of the windmill, such as a Darrie type and a gyromill type.

  Further, in recent years, a hybrid type vertical axis wind turbine improved so as to have both the Savonius effect and the gyromill effect described above has been improved and disclosed in, for example, Patent Document 1.

  In the vertical axis type windmill disclosed in the same document, a plurality of blades are provided at a predetermined angle around the rotation axis within a plane orthogonal to the vertical rotation axis. Airfoil having a streamlined cross-sectional shape used for airplanes such as airfoil, RAF airfoil, and Göttingen airfoil are used. Further, the blade inner surface (the surface on the rotating shaft side) of this blade has a notch formed by notching from the front edge to the rear edge starting at a position 35% to 45% from the front chord length. Is provided.

  In a vertical axis type wind turbine having such a blade structure, in a low wind speed region including a rotating stationary state (a rotational state where the ratio of the rotational speed of the blade to the wind speed is less than 1), the notch portion causes the wind from behind the blade to flow. The gyro produced by the wind from the front of the blade in the middle / high wind speed range (rotation state where the ratio of the blade rotation speed to the wind speed is 1 or more) The main rotational force is obtained by the mill effect.

Japanese Patent No. 3451085

  However, in recent years, with increasing interest in natural energy, the demand for wind power generation has been increasing, and in such a field of wind power generation, a windmill with further improved power generation efficiency has been demanded.

  In general, the thickness of streamlined wing blades used in airplanes such as NACA quadrilateral wings, FAF wings, and Göttingen wings is about 12% to 15% of the chord length. It was. In a conventional wind turbine for wind power generation, even if an airfoil having such a shape is used as a blade as it is and is changed temporarily, as disclosed in Patent Document 1, a part of the airfoil has a notch or the like. It was a grade to provide.

  Certainly, as disclosed in the same document, it is possible to improve the power generation efficiency of the windmill by providing a notch in a part of the blade, but the blade shape using the conventional airfoil as described above, In particular, the blade shape using an airfoil having a thickness of less than 15% of the chord length has a limit in further improving the power generation efficiency of the wind turbine.

  Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to increase the ratio of the thickness of the blade to the chord length and to form a notch formed in a part of the blade. Is to provide a vertical axis type wind turbine that improves power generation efficiency in a wide range of wind speeds.

  The above object of the present invention is to provide a vertical axis type wind turbine in which a plurality of blades are provided at equal angular intervals around a vertical rotation axis in a plane perpendicular to the vertical rotation axis. A streamlined asymmetric airfoil shape that is curved outward as compared to the inner surface and has a lift coefficient of 1.0 or more, and the blade inner surface of the blade is notched to a trailing edge starting from a predetermined position The blade has a thickness of 15% to 30% with respect to the blade chord length of the blade, and the predetermined position corresponds to the chord length of the blade. On the other hand, it is achieved by being 45% behind the front edge and before 65%.

  Moreover, the said objective is effectively achieved because the thickness of the said blade is 25 to 30% with respect to the chord length of the said blade.

  Further, the above object is effectively achieved by the predetermined position being a position of 45% to 55% from the leading edge with respect to the chord length of the blade.

  According to the vertical axis type windmill of the present invention, the thickness of the plurality of blades provided at equiangular intervals around the vertical rotation axis is set to 15% to 30% with respect to the chord length of the blade, and A notch was formed on the blade inner surface of the blade starting from a position 45% behind the front edge and ahead of the position 65% relative to the chord length. With this blade structure, the Reynolds number of the blade in a low wind speed range (about 1 to 3 m / sec) is about 105 or less, and the drag coefficient in this state can be increased (about 1.0), so a high Savonius effect is achieved. Can be maintained. Also, with this blade structure, the pressure distribution on the blade outer surface and blade inner surface can be concentrated forward, so that the wind pressure center in the blade can be moved forward greatly to increase the rotational direction component of aerodynamic force. it can. That is, the shape of the blade according to the present invention can greatly improve the gyromill effect in the medium / high wind speed region while maintaining the excellent Savonius effect in the low wind speed region. As a result, it is possible to improve the power generation efficiency in a wide range of wind speeds from startup to medium and high wind speeds without providing a new mechanism for improving the performance of the blade. The windmill which has can be manufactured at low cost.

It is a top view which shows the vertical axis type windmill which concerns on embodiment of this invention. It is a side view which shows the vertical axis type windmill seen from the arrow II direction in FIG. It is a principal part perspective view which shows the braid | blade of the vertical axis type windmill which concerns on embodiment of this invention. It is explanatory drawing regarding the blade shape of the vertical axis type windmill which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the wind tunnel apparatus used for the output test of the vertical axis type windmill which concerns on embodiment of this invention. It is a schematic side view which shows the test body used for the output test of the vertical axis type windmill which concerns on embodiment of this invention. It is a schematic side view which shows the power generation efficiency experiment apparatus used for the output test of the vertical axis type windmill which concerns on embodiment of this invention. It is a graph which shows the output result at the time of changing the position of a notch starting point, making blade thickness of a blade constant. It is a graph which shows the output result when changing the blade thickness while keeping the position of the notch starting point of the blade constant.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a top view showing a vertical axis wind turbine according to an embodiment of the present invention, and FIG. 2 is a side view showing the vertical axis wind turbine viewed from the direction of arrow II in FIG.

  As shown in FIGS. 1 and 2, the vertical axis wind turbine 1 according to the present embodiment includes a vertical rotating shaft 2 having a lower end connected to a generator or the like (not shown). Three airfoil blades 3 are arranged in parallel to the rotating shaft 2 at equal angular intervals (120 ° intervals in the present embodiment) along the circumferential direction of the same radius in a plane orthogonal to each other. Each blade 3 has a predetermined mounting angle (approximately 90 ° with respect to the support strut 4 in this embodiment) at the end of the support strut 5 extending radially from the center pole 4 connected coaxially with the rotary shaft 2. It is fixed with. A bearing 6 and a wind turbine support pole 7 are provided below the center pole 4, and rotatably support the rotating shaft 2 extending downward from the lower end of the center pole 4. In the vertical axis type windmill 1 having such a configuration, the rotational force of the blade 3 obtained from the wind power is transmitted to the rotary shaft 2 via the support strut 5 and the center pole 4.

  FIG. 3 is a perspective view of a main part showing a blade of the vertical axis wind turbine according to the embodiment of the present invention, and FIG. 4 is an explanatory diagram regarding the blade shape of the vertical axis wind turbine according to the embodiment of the present invention. is there.

  As shown in FIGS. 3 and 4, the surface of each blade 3 is formed by bending a thin plate material made of a light metal such as an aluminum alloy or a titanium alloy, or a composite material such as fiber reinforced plastic (FRP). The outer skin 8 is made up of. The blade 3 has an airfoil cross section having a streamline having a lift coefficient of 1.0 or more (preferably 1.0 to 1.4), and particularly in a main wing such as a light aircraft (an aircraft having a take-off weight of 5700 kgf or less). The shape of the asymmetric airfoil used is preferably, for example, a NACA quadrilateral airfoil, a RAF airfoil, or a Gottingen airfoil. In this embodiment, the surface of the blade 3 where the bulge is large (the outer peripheral surface) is the blade outer surface 3a of the blade 3, and the surface of the blade 3 where the bulge is small (inner peripheral surface) is the blade inner surface 3b. And

  Also, as shown in FIG. 3, ribs (support girders) 9 are inserted into the blade 3. The rib 9 is attached to the inside of the blade outer surface 3a and the blade inner surface 3b of the blade 3 by a rivet, an adhesive, or the like, and prevents deformation of the blade 3 during rotation. A part of the blade inner surface 3b of the blade 3, that is, a notch portion formed by notching a predetermined position as a starting point to the trailing edge on the rotating shaft 2 side (center pole 4 side) with respect to the chord. B is provided.

  In the hybrid wind turbine 1 having such a configuration and having the Savonius effect and the gyromill effect, the pressure distribution on the blade outer surface 3a and the blade inner surface 3b is concentrated forward as the blade thickness of the blade 3 is increased. Although the effect tends to improve, on the other hand, the ratio of the shape drag generated by the wind from the front of the blade 3 increases with respect to the drag obtained by the notch B, and the Savonius effect is reduced. There is also a tendency. Further, in such a hybrid type windmill 1, the Savonius effect tends to be improved as the starting point where the notch B is formed is on the front edge side. On the other hand, the notch B is a pressure around the blade. It also has a tendency to greatly affect the distribution and reduce the gyromill effect.

  Therefore, in consideration of such characteristics, each blade 3 of the vertical axis wind turbine 1 according to the present embodiment maintains an excellent Savonius effect while maintaining a middle / high wind speed range (6 [m / s] or more). It is formed with an airfoil that can greatly improve the gyromill effect. As shown in FIG. 4, when the blade chord length of the blade 3 is C, the blade thickness is T, and the distance from the leading edge of the blade 3 to the starting point of the notch B is P, as shown in FIG. 15 ≦ (T / C) ≦ 0.30 and 0.45 <(P / C) <0.65. That is, the blade thickness T of the blade 3 is 15% to 30% with respect to the chord length C of the blade 3, and the starting point of the notch B is 45% from the leading edge with respect to the chord length C. It is behind and 65% ahead.

  As described above, in the vertical axis type wind turbine 1 according to the present embodiment, the blade 3 thicker than the conventional one (blade type having a blade thickness of less than 15% with respect to the blade chord length) is used, and the blade inner surface 3b is notched. By making the starting point of the part B on the trailing edge side, the pressure distribution of the blade outer surface 3a and the blade inner surface 3b is concentrated on the leading edge side of the blade 3 while maintaining the excellent Savonius effect in the low wind speed region, thereby greatly increasing the gyromill effect. Can be improved.

  Hereinafter, the output test of the vertical axis type wind turbine according to the above-described embodiment of the present invention and the result thereof will be described.

  In order to confirm the output characteristics (power generation efficiency) when the blade thickness of the blade 3 and the position of the notch B are changed in the vertical axis wind turbine 1 having the above-described configuration, a Gottingen type recirculating wind tunnel device (FIG. 5) is used. ), The output of the wind turbine using the specimen (FIG. 6) arranged in the measurement unit of the wind tunnel apparatus and the power generation efficiency measuring apparatus (FIG. 7) for measuring the power generation efficiency of the generator set in the specimen. A test was conducted.

  In FIG. 5, the wind tunnel device 10 installed in the laboratory includes a suction pipe 11, a first current transformation pipe 12, a second current transformation pipe 13, a third current transformation pipe 14, a fourth current transformation pipe 15, and a second current transformation pipe. A blower 16 that rotates an impeller 16a provided in the current transformation pipe 13 is provided, and a maximum nozzle is provided from a 2000 [mm] × 2000 [mm] air outlet 15a provided in an end opening of the fourth current transformation pipe 15. Wind can be blown out at a wind speed of 60 [m / sec].

  Moreover, each part dimension of the wind tunnel apparatus 10 is L1 = 2000 [mm], L2 = 4200 [mm], L3 = 3200 [mm], L4 = 3200 [mm], L5 = 5000 [mm], L6 = 3500 [mm] ], L7 = 14158 [mm], L8 = 13196 [mm], L9 = 5000 [mm], L10 = 2656 [mm], L11 = 29900 [mm], L12 = 1696 [mm], L13 = 34252 [mm] It is.

  In this wind tunnel experiment, as shown in FIG. 6, a generator 21 is attached to a specimen (wind turbine) 1 ′ arranged in a measurement section between the air outlet 15 a of the wind tunnel device 10 and the opening end of the suction pipe 11. The windmill 1 ′ was rotated while arbitrarily changing the wind speed. At this time, the generator 21 is connected to the electronic load device, the optimum load is obtained by changing the load of the electronic load device, and the output (voltage, current, power) at this load is measured, whereby the generator 21 The power generation of the windmill 1 ′ considering the effect of power generation efficiency was obtained.

  Moreover, as shown in FIG. 7, the generator 21 used for the windmill 1 ′ is set in the power generation efficiency experiment device 22, and the same electronic load device and electronic power measurement device as those used in the wind tunnel experiment are used. An experiment was conducted to determine the power generation efficiency of the generator 21. In this experiment, the rotational torque meter 24 provided between the generator 21 and the motor 23 is used to measure the rotational moment and the rotational speed of the generator 21 to confirm the input, and the electronic power measuring device is used. The generated power was measured and the power generation efficiency of the generator 21 was obtained.

  In this wind tunnel experiment, a windmill 1 ′ having four blades 3 provided at equiangular intervals in a plane having a rotation diameter D = 1200 [mm] was used as a specimen. Then, the blade length H is set to 1200 [mm], the blade width (chord length) C is set to 220 [mm], and the “blade thickness ratio” or “notch position” of the blade 3 is set as shown in Table 1 below. Using eight types of specimens 1 ′ having different ratios, the power generation with respect to the wind speed of each specimen 1 ′ was measured. Here, the “blade thickness ratio” is the ratio of the blade thickness T to the chord length C of the blade 3 described in the above embodiment, and the “notch position ratio” is the blade chord of the blade 3 described in the above embodiment. This is the ratio of the distance P from the leading edge to the notch starting point with respect to the length C.

供試体（１）〜（４）は、ブレード３の翼厚を一定にして、切欠部Ｂの切欠起点の位置を変更した場合の出力特性を比較するためのものであり、その結果は、図８に示すとおりである。ブレード３の切欠部Ｂは、サボニウス効果によって低風速でも風車を起動可能にする働きがあるため、その切欠起点の位置は、風車の起動風速に大きく影響を与える。図８に示すように、ブレード３の切欠起点の位置が、３５％（供試体（１））、４５％（供試体（２））、５５％（供試体（３））と増加するにつれて起動風速が大きくなり、６５％（供試体（４））では５５％の略２倍の起動風速を要するという結果になった。

Specimens (1) to (4) are for comparing the output characteristics when the blade 3 has a constant blade thickness and the position of the notch start point of the notch B is changed. As shown in FIG. The notch B of the blade 3 has a function of enabling the windmill to be activated even at a low wind speed due to the Savonius effect. Therefore, the position of the notch starting point greatly affects the activation wind speed of the windmill. As shown in FIG. 8, it starts as the position of the notch starting point of the blade 3 increases to 35% (specimen (1)), 45% (specimen (2)), and 55% (specimen (3)). The wind speed increased, and 65% (specimen (4)) required approximately twice the startup wind speed as 55%.

  On the other hand, in the middle wind speed range (6 to 12 [m / sec]), the rotational force is generated by the forward direction component of the aerodynamic force due to the gyromill effect of the blade 3, so that the position of the notch starting point of the blade 3 is 35%, 45 However, the output of 65% at a wind speed of 10 [m / sec] did not increase so much as compared with the output of 55%. This means that the notch portion B having a notch position ratio of 55% or more does not significantly affect the pressure distribution around the blade 3, and even if the position of the notch starting point is 65% or more, The increase in the gyromill effect cannot be expected so much.

  Therefore, the starting point of the notch B formed in the blade 3 is 65% behind the position of 45% from the leading edge with respect to the chord length C of the blade 3 in consideration of the power generation efficiency at the start wind speed and the medium wind speed. It is preferable that it is before the position, and it is particularly desirable that the position be 45% to 55%.

  In the specimens (5) to (8), the position of the notch starting point of the blade 3 is kept constant at 55%, which is the optimum value obtained from the output results of the specimens (1) to (4). This is for comparing the output characteristics when the blade thickness is changed, and the result is as shown in FIG.

  In the vertical axis type windmill 1 as in the present embodiment, the drag generated when the notch B receives wind from the rear of the blade 3 is larger than the shape drag generated by the wind from the front of the blade 3, and this difference in effectiveness A rotational force (particularly a starting force) of the windmill 1 is generated. Increasing the blade thickness of the blade 3 increases the wind receiving area of the notch B, and the drag generated by the wind from the rear of the blade 3 increases in proportion to the increase in the wind receiving area. The shape drag of the blade 3 due to the wind from the front increases.

  As shown in FIG. 9, the starting wind speed of each specimen (5) to (8) was slightly increased even when the blade thickness was increased at a blade thickness ratio of 15 to 30%. In 30 to 35%, the increase in the starting wind speed when the blade thickness was increased was remarkable. This is because when the blade thickness ratio exceeds 30%, the shape drag of the blade is greatly increased, so that the drag difference between the drag generated by the notch B and the shape drag is reduced, thereby reducing the starting moment (rotation force). It means to end up. That is, the increase in the shape drag of the blade 3 accompanying the increase in the blade thickness at a blade thickness ratio of 15 to 30% is substantially constant, but the shape drag tends to increase greatly when it exceeds 30%. It will greatly affect the increase.

  On the other hand, in the middle wind speed range (6 to 12 [m / sec]), a rotational force is generated by the forward direction component of the aerodynamic force due to the gyromill effect of the blade 3, so that the blade thickness ratio of the blade 3 is 15% (specimen) (5)), the output increased as 25% (specimen (6)) and 30% (specimen (7)), but the output of 35% (specimen (8)) was 30% It did not increase so much compared to the output of. This is because when the blade thickness ratio is 15% to 30%, the pressure distribution of the blade outer surface 3a and the blade inner surface 3b of the blade 3 is concentrated forward as the blade thickness increases, and the gyromill effect is improved. If the blade thickness ratio exceeds 30%, it means that increasing the blade thickness beyond that does not have a significant effect on the pressure distribution around the blade 3, Even if it is 30% or more, it cannot be expected to increase the gyromill effect further.

  Therefore, the blade thickness of the blade 3 is preferably 15% to 30% with respect to the chord length C of the blade 3 in consideration of the power generation efficiency at the start wind speed and the medium wind speed, and particularly 25% to 30%. The position is desirable.

  As described above, in the vertical axis wind turbine 1 according to the embodiment of the present invention, the blade thickness T of the blade 3 is 15% to 30% with respect to the chord length C, and the starting point of the notch B is the blade. By adopting a new wing shape that is 45% behind the front edge and 65% ahead of the chord length C, the power generation efficiency of the windmill 1 is greatly improved in a wide range of wind speeds. Can be made.

  Further, since the blade 3 of the vertical axis wind turbine 1 according to the embodiment of the present invention does not necessarily add a new mechanism for improving such performance, the apparatus is not enlarged or complicated. It can be manufactured at low cost.

  As mentioned above, although embodiment and Example of this invention were described concretely, this invention is not limited to this, It can change suitably in the range which does not deviate from the meaning.

DESCRIPTION OF SYMBOLS 1 ... Vertical axis type windmill 2 ... Rotating shaft 3 ... Blade 3a ... Blade outer surface 3b ... Blade inner surface 4 ... Center pole 5 ... Support strut 8 ... Skin B ..Cut portion C ... Cord length T ... Blade thickness P ... Distance from blade leading edge to notch start point

Claims (1)

A vertical axis type windmill in which a plurality of blades are provided at equiangular intervals around a vertical rotation axis in a plane perpendicular to the vertical rotation axis,
The blade is a streamlined asymmetric airfoil formed such that the outer surface of the blade is curved outward as compared with the inner surface of the blade and has a lift coefficient of 1.0 or more.
The blade inner surface of the blade has a notch formed by notching to a trailing edge starting from a predetermined position,
The blade has a thickness of 15% to 30% of the chord length of the blade; and
The vertical axis wind turbine according to claim 1, wherein the predetermined position is behind 45% from the front edge and ahead of 65% of the chord length of the blade.

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