WO2007148826A1

WO2007148826A1 - Wind power generator

Info

Publication number: WO2007148826A1
Application number: PCT/JP2007/062836
Authority: WO
Inventors: Toshihiro Kamatsuchi; Toshiyuki Arima
Original assignee: Honda Motor Co., Ltd.
Priority date: 2006-06-21
Filing date: 2007-06-20
Publication date: 2007-12-27

Abstract

A wind power generator includes a duct (23) having a convergent nozzle part (23A) defining a converging airflow passage extending from an air inlet (37) toward an air outlet (38), and a divergent diffuser part (23B) defining divergent airflow passage extending contiguously from a downstream end of the convergent airflow passage to the air outlet. The diffuser part has plurality of slots (36) formed therein. The slots are formed by and between adjacent edges (26b and 27a, 27b and 28a, 28b and 29a) of a plurality of wing elements arranged in an axial direction of duct such that the adjacent edges of the wing elements overlap each other in the axial direction of the duct.

Description

DESCRIPTION

WIND POWER GENERATOR

Technical Field

The present invention relates to an improvement in a wind power generator of the type having a duct in which a generator body is installed.

Background Art

As the interest in global environmental issue rises, the wind power generation using natural wind energy with small environmental load has attracted attention recently. Especially, there is growing demand for small- sized wind power generators that can be installed independently from the commercial power supply. In the field of such small-sized wind power generators, the development of a duct-equipped wind power generator is now going on as it is effective in increasing the wind velocity at a collision with a windmill to thereby improve the power output.

In the duct-equipped wind power generator, however, since merely arranging a windmill in a duct cannot lead to a large wind-velocity increasing effect due to a pressure drop created in the wake downstream from the windmill, various measures have been proposed to recover the pressure in the wake downstream from the windmill.

According to one example of such prior proposals disclosed in Japanese Patent LaidOpen Publication (JP-A) No. 2003-328921, the duct-equipped wind power generator takes the form of a double wind-collecting device. As shown in Fig. 7 hereof, the double wind-collecting device 400 comprises a propeller windmill 402 having a plurality of blades 401, a convergent tube 403, and a divergent tube 404 disposed downstream of the convergent tube 403 so as to form jointly with the convergent tube 403 a duct in which the windmill 402 is disposed. The duct has a plurality of circumferential slots 411 to 416 formed in the convergent and divergent tubes 403 and 404 for introducing outside air therethrough into the duct to thereby supply energy to the air inside the duct for the purpose of preventing airflow separation from occurring.

The double wind-collecting device 400 of the foregoing construction is not fully satisfactory in that the slits 411-416 are relatively long and narrow and hence involve a great pressure loss, making it difficult to supply a high pressure to the internal spaces of the duct. It is therefore impossible to supply sufficient energy to the airflow inside the duct.

Furthermore, the long and narrow slots 411-416 are difficult to machine and incur additional cost. In addition, when the configurations of the slots 411-416 and the tubes 403, 404 are to be changed or modified, replacement of the entire duct (i.e., tubes 403, 404) are necessary, resulting in a significant cost increase.

It is accordingly an object of the present invention to provide a wind power generator, which is able to increase power output of the wind power generator, can be manufactured at a relatively low cost, and is readily adaptable to design modification without incurring undue additional cost. Disclosure of the Invention

According to a first aspect of the present invention, there is provided a wind power generator comprising: a duct having an air inlet at a first end thereof and an air outlet at a second end opposite to the first end, the duct further having a convergent nozzle part defining a converging airflow passage extending from the air inlet toward the air outlet, and a divergent diffuser part contiguous with the nozzle part and defining a divergent airflow passage extending contiguously from a downstream end of the convergent airflow passage to the air outlet; a rotary shaft rotatably supported in the duct by a support member extending from an inner surface of the duct; a rotor attached to the rotary shaft; and an electric generator driven by rotation of the rotor, wherein the diffuser part has a plurality of slots formed therein, and the slots are formed by and between adjacent edges of a plurality of wing elements arranged in an axial direction of duct such that the adjacent edges of the wing elements overlap each other in the axial direction of the duct.

By virtue of the slits, it is possible to supply energy to the stream of air inside the diffuser part of the duct to thereby recover the pressure inside the diffuser part to the extent that separation of airflow from an inner surface of duct does not occur. Furthermore, by virtue of the overlapping arrangement of the adjacent edges of the wing elements, the slots are relatively small in length and hence able to guide the outside air into a given direction with little pressure loss involved as the outside air is introduced into the duct. This makes it possible to increase the amount of energy supplied into the diffuser part of the duct, which will increase the velocity of air flowing into the duct and hence enables the rotor to rotate at high speeds, leading to increased power output of the wind power generator.

The overlapping arrangement of the wing elements further provides cost reduction as the slots can be formed easily without requiring precise machining operation.

Furthermore, by virtue of the wing elements arranged in overlapping relation in the axial direction of the duct, at least the diffuser part of the duct is readily adaptable to design modification without requiring replacement of the entire duct.

Preferably, each of the wing elements is formed by a divergent annular ring member, and the plurality of wing elements jointly forms at least the diffuser part of tlie duct. The diffuser part thus formed by a plurality of divergent annular ring members arranged in the axial direction of the duct is easy to maintain and readily adaptable to design modification.

According to a second aspect of the present invention, there is provided a wind power generator comprising^ a duct having an air inlet at a first end thereof and an air outlet at a second end opposite to the first end, the duct further having a convergent nozzle part defining a converging airflow passage extending from the air inlet toward the air outlet, and a divergent diffuser part contiguous with the nozzle part and defining a divergent airflow passage extending contiguously from a downstream end of the convergent airflow passage to the air outlet; a rotary shaft rotatably supported in the duct by a support member extending from an inner surface of the duct; a rotor attached to the rotary shaft; an electric generator driven by rotation of the rotor; and an external energy- addition means disposed in the diffuser part for exerting an external energy to a stream of air flowing downstream of the rotor, wherein the external energy- adding means comprises a heating device. The heating device may be a heat pump or an electric heater.

With the heating device thus provide as an external energy- addition means, the air as it flows along the diffuser is heated so that the air inside the diffuser part recovers its initial pressure (inflow pressure) before it reaches the air outlet of the duct. It is therefore possible to increaser the velocity of air flowing into the duct, leading to high speed rotation of the rotor with a resulting increase in power output of the wing power generator.

Preferably, the wind power generator further comprises a stator disposed upstream of the rotor for deflecting a stream of air coming to the rotor toward a rotating direction of the rotor. The stator is simple in construction but readily possible to change the inflow angle of air coming to the rotor. By thus providing the stator, it is possible not only to reduce the number of parts of the wind power generator for cost-saving, but also to increase the momentum of air in the rotating direction of the rotor for increasing power output of the wind power generator. The stator increases the inflow velocity of the air coming to the rotor with the result that the rotor can rotate at high speeds, leading to increased power output of the wind power generator.

Preferably, the stator has a deflection angle, the rotor has a deflection angle, and the deflection angle of the stator and the deflection angle of the rotor are equal in absolute value to each other. With this arrangement, since the outflow angle of air leaving from the rotor corresponds to the inflow angle of air coming to the stator, the air is allowed to leave the rotor in a direction parallel to the axis of rotation of the rotor and rectifies the wake of the rotor.

As a result, the flow velocity of air coming into the duct increases to thereby enable the rotor to rotate at high speeds and increase power output of the wind power generator.

The wind power generator may further comprise a second stator disposed downstream of the rotor for rectifying a stream of air flowing backward of the rear stator. Brief Description of the Drawings

Fig. 1 is an axial cross-sectional view of a wind power generator according to a first embodiment of the present invention!

Fig. 2(a) is a diagrammatical view illustrative of the operation of a front stator and a rotor of the wind power generator, the view showing a condition immediately before the rotor starts rotation;

Fig. 2(b) is a view similar to Fig. 2(a), but showing a different condition in which the rotor is rotating at a constant speed; Fig. 3(a) is a diagrammatical view showing a vector triangle obtained from an inflow air velocity and an outflow air velocity of the rotor;

Fig. 3(b) is a diagrammatical view showing a vector triangle obtained from an inflow air velocity and an outflow air velocity of the rotor, which are different from the inflow and outflow air velocities shown in Fig. 3(a);

Fig. 3(c) is a diagrammatical view showing another vector triangle obtained from an inflow air velocity and an outflow air velocity of the rotor, which are different from the inflow and outflow air velocities shown in Fig. 3(a); Fig. 3(d) is a diagrammatical view showing still another vector triangle obtained from an inflow air velocity and an outflow air velocity of the rotor, which are different from the inflow and outflow air velocities shown in Fig. 3(a);

Fig. 3(e) is a diagrammatical view showing another vector triangle obtained from an inflow air velocity and an outflow air velocity of the rotor, which are different from the inflow and outflow air velocities shown in Fig. 3(a);

Fig. 4(a) is a graph showing the relationship between the pressure variations and the wind velocity variations occurring in a wind power generator unit;

Fig. 4(b) is an enthalpy-entropy chart showing a state variation cycle occurring in the wind power generator unit;

Fig. 5 is an axial cross-sectional view of a wind power generator according to a second embodiment of the present invention; Fig. 6 is an axial cross-sectional view of a wind power generator according to a third embodiment of the present invention; and

Fig. 7 is an axial cross-sectional view of a conventional wind power generator.

Best Mode for Carrying Out the Invention

Certain preferred embodiments of the present invention will be described below in greater detail with reference to the accompanying sheets of drawings.

Fig. 1 shows in cross section a wind power generator according to a first embodiment of the present invention. The wind power generator in the illustrated embodiment is so-called "duct-equipped wind power generator", which is equipped with a duct as will be described later. As shown in Fig. 1, the wind power generator 10 comprises a support base 12 attached to a mount table or base 11, and a wind power generator unit 13 supported by the support base 12 in such a manner that the wind power generator unit 13 is rotatable in a horizontal plane.

The support base 12 includes a tubular member 16 disposed vertically and anchored to the mount base 11 by means of flat head bolts 15, and a vertical shaft 21 rotatably mounted in the tubular member 16 via a pair of ball bearings 17 and 18. The vertical shaft 21 has an upper end connected to a lower portion of the wind power generator unit 13, so that the wind power generator unit 13 is rotatable in a horizontal plane about an axis of the vertical shaft 21 so as to orient itself to the direction of wind at all times. In Fig. 1, reference numeral 19 denotes a collar fitted in the tubular member 16 for supporting the ball bearing 17, and reference numeral 22 denotes a dust seal. The ball bearing 17 bears loads acting in a direction along the vertical shaft 21. The wind power generator unit 13 includes a duct 23, a wind power generator body 24 disposed in the duct 23, and front and rear stators 41 and 42, which serve also as connecting members connecting the duct 23 and the wind power generator body 24. The duct 23 is so-called "multi-wing" type duct having a multiplicity of annular wings elements 26 to 29 connected together by a plurality of connecting members 31 to 33. The connecting members 31-33 are formed with slots 36 as openings through which outside air is introduced into the duct 23. The duct 23 has an air inlet 37 and an air outlet 38.

The duct 23 has a front portion formed into a nozzle part 23A of convergent channel-shaped configuration having a cross-sectional area reducing gradually in a direction from the air inlet 37 toward the air outlet 38, and a main portion extending continuously and rearward from the nozzle part 23A and formed into a diffuser part 23B of divergent channel-shaped configuration having a cross-sectional area gradually increasing toward the outlet opening 38 of the duct 23. The convergent nozzle part 23A defines a convergent airflow passage extending from the air inlet 37 toward the air outlet 38 and terminating far short of the air outlet 38, while the divergent diffuser part 23B defines a divergent airflow passage extending continuously from a downstream end of the convergent airflow passage to the air outlet 38.

Each of the annular wing elements 26 to 29 is formed by a divergent annular ring member. The wing elements (divergent annular ring members) 26-29 of the duct 23 are arranged such that a rear edge 26b, 27b, 28b of each respective annular wing element 26, 27, 28 and a front edge 27a, 28a, 29a of the adjacent annular wing element 27, 28, 29 are overlapped with each other in an axial direction of the duct 23 (which is parallel to the axis of an output shaft 44 described later). With this overlapping arrangement of the adjacent edges of the annular wing elements 26-29, it is possible to shorten the length of the slots 36.

The power generator body 24 generally comprises a nacelle 43 forming a fuselage mounted inside the duct 23 via the front stator 41 and the rear stator 42, a horizontal rotary shaft 44 rotatably mounted in a front half of the nacelle 43, a rotor 46 mounted to the horizontal rotary shaft 44 for rotation therewith, an output shaft 47 rotatably mounted in a rear half of the nacelles 43, a speed-up gear 48 coupled to a rear end of the horizontal rotary shaft 44 and a front end of the output shaft 47, an electric generator 51 disposed on a rear end portion of the output shaft 47, an output cable 52 for taking out electric power from the generator 51, and a control unit 53 for performing overload protection of the rotor 46 and output control of the generator 51.

The front stator 41 is formed by a plurality of stator blades 61 forming wings, which change or deflect the direction of wind toward the rotor 46 so that the wind flowing into the duct 23 will impinge on the rotor 46, and which serve also as a support member for supporting the wind power generator body 24 relative to the duct 23. The stator blades 46 are connected at one end to the duct 23 via an intermediate plate or bracket 63 by means of fiat head screws 64 and, at the other end, to a front nacelle 66 by means of flat head screws 67. The front nacelle 66 forms a part of the nacelle 43.

The rear stator 42 is formed by a plurality of stator blades 71 forming wings, which rectify the stream of wind flowing backward of the rear stator 42, and which serve also as a support member for supporting the wind power generator body 24 relative to the duct 23. The stator blades 71 are connected at one end to the duct 23 via an intermediate plate or bracket 73 by means of flat head screws 74 and, at the other end, to a rear nacelle 76 by means of flat head screws 77. The rear nacelle 76 forms a part of the nacelle 43.

The nacelle 43 is constituted by the front nacelle 66 and the rear nacelle 76. The front nacelle 66 retains therein a ball bearing 81 by means of which the horizontal rotary shaft 44 is rotatably supported. Reference numeral 83 denotes a cap attached to a front end of the front nacelle 66 for rectifying the stream of wind coming to the duct 23

The rear nacelle 76 has a two-piece structure composed of a front body 85 and a rear body 86 that are fitted together end to end. The front nacelle body 85 retains therein a ball bearing 87 by means of which a front end portion of the output shaft 47 is rotatably supported. The rear nacelle body 86 is provided with a coil support portion 92, which supports a coil 91 and retains a ball bearing 93 by means of which a rear end of the output shaft 47 is rotatably supported.

The rotor 46 has a rotor case 102 connected by spline- coupling at a front end thereof to the horizontal rotary shaft 44 and rotatably mounted to the front nacelle body 85 via a needle bearing 101, a support ring 103 connected to an inner peripheral surface of the rotor case 102 for supporting the rotor case 102 and connected by spline-coupling to the horizontal rotary shaft 44, and a plurality of rotor blades 106 connected to a front peripheral wall of the rotor case 102 by means of flat head screws 104.

The rotor 46, horizontal rotary shaft 44, ball bearing 81 and needle bearing 101 are component parts jointly forming a windmill 107, which is classified into a horizontal shaft propeller type windmill.

The speed-up gear 48 is comprised of a planetary gear train or mechanism having a ring gear 111 connected by spline-coupling to the rear end of the horizontal rotary shaft 44, a plurality of planet gears 112 rotatably mounted on a disk portion 85a of the front nacelle body 85 in meshing engagement with the ring gear 111, and a sun gear 116 connected by spline-coupling to the front end of the output shaft 47 and meshing with the planet gears 112. With the speed-up gear 48 thus provided, rotation of the horizontal rotary shaft 44 is transmitted at an increased speed to the output shaft 47. The electric generator 51 includes a plurality of permanent magnets 122 attached to a small- diameter portion 121 formed as an integral rear end extension of the output shaft 47, and the coil 91 arranged to surround the permanent magnets 122 with an annular air gap denned therebetween. Next, operations of the front stator 41 and the rotor 46 of the duct- equipped wind power generator will be described hereinafter with reference to Figs. 2(a) and 2(b). In Figs. 2(a) and 2(b), two adjacent stator blades 61 of the front stator 41 and two adjacent rotor blades 106 of the rotor 46 are shown in cross section in conjunction with the velocity of airflow, and the peripheral velocity of the rotor 46. In these figures, a horizontal direction represents a direction along the axis of the horizontal rotary shaft 44 (Fig. l), and a vertical direction represents a rotating direction of the rotor 46.

Fig. 2 (a) illustrates a condition immediately before the rotor 46 starts rotating with the wind passing successively through an airflow passage between the two adjacent stator blades 61 of the front stator 41 and through an airflow passage between the tow rotor blades 106 of the rotor 46.

As shown in Fig. 2(a), the airflow passage between the stator blades 61 is formed into a convergent nozzle part having a leading edge cross-sectional area (i.e., a cross-sectional area taken along a straight line 131) which is larger than a trailing edge cross-sectional area (i.e., a cross-sectional area taken along a straight line 132. Similarly, the airflow passage between the rotor blades 106 is formed into a convergent nozzle part having a leading edge cross- sectional area (i.e., cross-sectional area taken along a straight line 133) which is larger than a trailing edge cross -sectional area (i.e., a cross-sectional area taken along a straight line 134.

When the wind flows into the front stator 41 at an absolute velocity Vl (with an inflow angle a i (= 0° )), it is deflected by the front stator 41 toward the rotating direction of the rotor 46 and, by virtue of the convergent nozzle-shaped airflow passage, the wind is increased in speed up to an absolute velocity V2 (with an outflow angle a 2) and finally flows out of the front stator 41. In this instance, if the deflection angle of the front stator 41 is represented by E S, E S = CK ₁ - α 2 = " α 2 (see Fig. 2(b)).

Subsequently, the wind flows into the rotor 46 at the absolute velocity V2 (with an inflow angle j3 ₁ (= «2)), passes through the rotor 46 at a relative, speed W3 relative to the rotor 46 (having a peripheral speed u = 0), and finally flows out of the rotor 46 at an absolute velocity V4 (with an outflow angle β 2. In this instance W3 = V4.

As a consequence, the wind having an absolute velocity W42 (which is the difference between the absolute velocity V4 and the absolute velocity V2, as indicated by one side of a vector triangle) acts on the rotor 46 in the rotating direction of the rotor 46 whereupon the rotor 46 starts rotating in the rotating direction. In Fig. 2 (a), reference numeral 136 denotes a straight line, which passes through the origins of the absolute velocities V2 and V4 indicated by vectors and is parallel to the horizontal rotary shaft 44 (Fig. l) of the rotor 46.

Fig. 2(b) illustrates a condition in which the rotor 46 is rotating at a constant peripheral velocity u with the wind passing through the front stator 41 and the rotor 46.

The wind passes through the rotor 46 at a relative velocity W5 relative to the rotor 46 and flows out of the rotor 46 at an absolute velocity V6 (with an outflow angle β 3 (= 0° ), not shown). In this instance, if the deflection angle of the rotor 46 is represented by ε r = JS ₁ - JS s =_IS ₁. Thus the wind having an absolute velocity V62 (which is the difference between the absolute velocity V2 and the absolute velocity V6) acts on the rotor 46 in the rotating direction of the rotor 46. In other words, if the letter M represents the mass flow rate of air per unit time, it can be considered that the rotor 46 is subjected to a momentum M ^• V62, which is the difference of a momentum M- V2 of inflow air to the rotor 46 and a momentum M- V6 of outflow air from the rotor 46. The momentum M- V62 increases with the inflow angle j3 i of the wind coming to the rotor 46. Accordingly, by increasing the inflow angle ]3 i , it is possible to exert a sufficiently large momentum to the rotor 46 in the rotating direction thereof.

On the other hand, since ε s = - a i and ε r = j3 i where ε s is the deflection angle of the front stator 41 and ε r is the deflection angle of the rotor 42, and since β i = a %, we can write ε s = - ε r. This means that the deflection angle ε s of the front stator 41 and the deflection angle ε r of the rotor 46 are equal in absolute value and opposite in direction.

By thus setting the condition ε s = - ε r, it is possible to set the outflow angle j33 of the rotor 46 to be zero (i.e., the wind is allowed to flow out of the rotor in a direction parallel to the horizontal rotary shaft 44 (Fig. l) of the windmill 107) when the inflow angle α i _Of the front stator 41 is zero (i.e., when the wind flows into the front stator 41 in a direction parallel to the horizontal rotary shaft 44). By thus setting of the outflow angle j33 relative to the inflow angle a 1, it is possible to rectify the wake flow occurring downstream from the rotor 46.

Figs. 3(a), 3(b), 3(c), 3(d) and 3(e) are views illustrative of the operations of the rotor 46 by way of vector triangles taken in conjunction with the velocity of inflow air and the velocity of outflow air of the rotor 46.

In Fig. 3(a), reference character 138 denotes a straight line parallel to the horizontal rotary shaft 44 (Fig. l) of the rotor 46, V6 an absolute velocity of inflow air coming to the rotor 46, V8 an absolute velocity of outflow air leaving from the rotor 46, and V87 an absolute velocity represented by the difference of the absolute velocity V7 and the absolute velocity V8. These absolute velocities

V7, V8 and V87 together form a vector triangle, and the origins of the absolute velocities V7 and V8 are located on the straight line 138. This applies to Figs. 3(b) to 3(e). As shown in Fig. 3(a), the inflow air has an angle y i to the straight line 138 parallel to the horizontal rotary shaft 44 of the rotor 46 (inflow angle = y i ), the outflow air has an angle y i to the straight line 138 (outflow angle = 72 ), and the absolute velocity V87 does not intersect the straight line 138.

Similarly, in Fig. 3(b), the inflow air has an inflow angle 73, (which is equal to zero because the absolute velocity V7 is aligned or coaxial with the straight line 138), the outflow air has an outflow angle 74, and the absolute velocity V87 intersects the straight line 138 at the terminus thereof.

In Fig. 3(c), the inflow air has an inflow angle 75 and the outflow air has an outflow angle y β where 75 = 7 6. This means that the absolute velocity V7 and the absolute velocity V8 are equal in magnitude with each other. Thus, the absolute velocities V7 and V8 are symmetric with each other with respect to the straight line 138, and the absolute value V87 intersects the straight line 138 at right angles.

Similarly, in Fig. 3(d), the inflow air has an inflow angle 7 7, the outflow air has an outflow angle 7 8, (which is equal to zero because the absolute velocity V8 is aligned or coaxial with the straight line 138), and the absolute velocity V87 intersects the straight line 138 at the origin thereof.

In Fig. 3(e), the inflow air has an inflow angle 79, and the outflow air has an outflow angle 7 10, and the absolute velocity V87 does not intersect the straight line 138.

It will be readily appreciated that the inflow angles 7 1, 73, 75, 77 and 7 9 and the outflow angles 7 2, 7 4, 7 β, 7 s and 7 10 depend on the respective wing configurations of the front stator 41 (Fig. l) and the rotor 46

(Fig. 1).

In Figs. 3(a) and 3(e), due to the absolute velocity V87 not intersecting the straight line 138, the angle formed between the absolute velocity V87 and the straight line 138 becomes small and, hence, a vector component of the absolute velocity V87, which is oriented in the rotating direction of the rotor 46 aligned with the vertical direction in Figs. 3(a) and 3(e), is small. Thus, the rotating velocity of the rotor 46 does not increase so much.

By contrast, in Figs. 3(b) to 3(d), because the absolute velocity V87 intersects the straight line 138, the angle formed between the absolute velocity V87 and the straight line 138 becomes large and, hence, a vector component of the absolute velocity V87, which is oriented in the rotating direction of the rotor 46, becomes large correspondingly. Especially in the case of Fig. 3(c), the absolute velocity V87 intersects the straight line 138 at right angles to the straight line 138, so that the absolute velocity V87 in itself acts in a direction tending to rotate the rotor 46, enabling the rotor 46 to rotate at a maximum speed.

As appears clear from the foregoing description made with reference to Figs. 2 and 3, by using the front stator 41, the inflow angle β i (Fig. 2) of the wind coming to the rotor 46 can be enlarged to thereby increase the deflection angle ε r. It is therefore possible to increase the momentum of wind acting on the rotor blades 106 in the rotating direction of the rotor 46.

Fig. 4(a) is a graph showing the relationship between the pressure variations and the wind velocity variations occurring within the duct 23. In Fig. 4(a), circled numbers 0 to 6 denotes respective positions of various parts of the wind power generator unit 13. Especially, circled number 0 denotes the position of the air inlet 37 of the duct 23, circled number 1 denotes the position of the leading edge of the front stator 41, circled number 2 denotes the position of the trailing edge of the front stator 41, circled number 3 denotes the position of the front end of the rotor 46, circled number 4 denotes the position of the rear end of the rotor 46, circled number 5 denotes the position of the slit 36 (only one shown), and circled number 6 denotes the position of the air outlet 38 of the duct 23.

At the position of circled number 0, the pressure P is Po. As the wind passes through the front stator 41, adiabatic expansion occurs in the convergent nozzle-shaped airflow passages between the adjacent stator blades 61 of the front stator 41. In this instance, the pressure P drops from Po to P3

(with temperature depression), as indicated by the solid line shown in Fig. 4(a).

Then, the wind passes through the convergent nozzle-shaped airflow passages defined between the adjacent rotor blades 106 of the rotor 46 during which time the pressure P further drops to P4. The amount of decrease in pressure energy of the wind is exerted as rotational energy to the rotor 46.

Subsequently, at the position of circled number 5, surrounding air of the duct 23 (Fig. l) is taken or drawn from the slot 36 into the duct 23 to thereby inject energy to the wake flow of the rotor 46. In this instance, the energy injection operation of the slot 36 is combined with the operation of the divergent channel-shaped diffuser part 23B of the duct 23 with the result that the wake flow of the rotor 46 recovers the pressure, which wiJl then become equal to or greater than Po at the position of circled number 6. In this instance, if the pressure P is greater than Po, it will fall to Po at the position downstream of the duct 23. On the other hand, at the position of circled number 0, the wind velocity

V is V₀. From the position of circled 0 to the position of circled 1, the wind velocity V increases progressively from Vo to V₁, as indicated by the broken line in Fig. 4(a). As the wind passes through the front stator 41, namely, from the position of circled number 1 to the position of circled number 2, the wind velocity V further increases from V₁ to V3 as the pressure P decreases as discussed above. Thus, the kinetic energy of the wind increases and the rotor 46 rotates with increased kinetic energy. Then, the wind passes through the rotor 46 during which time the wind velocity V decreases progressively as occurring between the position of circled number 3 and the position of circled number 4. Subsequently, the wind velocity V further drops progressively with an increase in pressure P until the wind reaches the position of circled number 6. At the position downstream of the duct 23, the wind velocity V returns to Vo.

Fig. 4(b) is an enthalpy-entropy chart showing a state variation cycle occurring in the wind power generator unit 13. In Fig. 4(b), numbers 0 to 6 corresponds to the circled numbers 0 to 6 shown in Fig. 4(a). As shown in Fig. 4(b), at the position of number 0, the pressure P is Po.

From the position of number 0 to the position of number 3 where the pressure P is P3 (and entropy S is S3), air undergoes adiabatic expansion caused due to the convergent nozzle-shaped airflow passages between the adjacent stator blades 61 of the front stator 41. Then, from the position of number 3 to the position of number 4 (where the entropy S is S₄), the pressure P drops from P3 to P₄ due to expansion of air caused due to the convergent nozzle-shaped airflow passages between the adjacent rotor blades 106 of the rotor 46. Thus, power per unit mass flow rate of air at the rotor 46 is equal in amount to the difference in enthalpy between I3 and I₄. As the wind flows from the position of circled number 4 through the position of circled number 5 to the position of circled number 6, by virtue of the pressure recovery achieved by a combination of diffusing operation of the divergent channel-shaped diffuser part 23B of the duct 23 and energy injecting operation of the slot 36, the enthalpy increases progressively to the extent that at the position of number 6, the pressure Pe is equal to or greater than the pressure Po at the position of number 0. In the case where the pressure Pβ at the position of number 6 is greater than Po, the pressure P will return to Po at the position of numeral 0. The state variation cycle of the wind power generator unit 13 has been described. This cycle holds for when Pβ is equal to or greater than Po.

When the entropy S is S3, an enthalpy I on an isobaric curve of pressure P4 is I41, and the efficiency η WT of the windmill 107 (Fig. l) is^:

As discussed above with reference to Figs. 4(a) and 4(b), according to the present invention, adiabatic expansion of air caused by the front stator 41 is utilized to lower the pressure (reduce the pressure energy) and also lower the temperature (reduce the internal energy). In other words, by reducing the static enthalpy, the kinetic energy is increased.

A total enthalpy H (per unit mass flow rate) of the wind is the sum of a kinetic energy and a static energy, as expressed by the following Equation (l) or (2). H = 1/2- V² + (U + P/ p ) ^{• • • •} (1) where V^: wind velocity, TJ: internal energy, P^ pressure, and p ^'■ density. In

Equation (l), the first term of the right side represents the kinetic energy, and the second term represents the static enthalpy.

H = 1/2- V² + CpT ^{• • • •} (2) where V^: wind velocity, Cp ^: isobaric specific heat, and T- temperature. In

Equation (2), the first term of the right side represents the kinetic energy, and the second term represents the static enthalpy. Work W taken by the rotor 46 is the difference between a total enthalpy of the wind coming to the rotor 46 and a total enthalpy leaving from the rotor

46. The work W is expressed by either the following Equation (3) when applying Equation (l), or the following Equation (4) when applying Equation (2).

W = H₁ - H₂

= 1/2- (V₁ ² + V₂ ² ) + (UrU₂) + 1/ p ^• (P₁ - P₂ ) ^{• • • •} (3)

In Equation (3), the first term of the right side represents the kinetic energy, and the second and third terms represent the static enthalpy. W = H₁ - H₂

= 1/2- (V₁ ² + V₂ ² ) + Cp- (TrT₂) ^{• • ■ •} (4)

In Equation (4), the first term of the right side represents the kinetic energy, and the second term represents the static enthalpy.

Thus, work P, which the rotor 46 can get from the wind of mass flow rate G, is expressed by the following Equation (5).

P = GW ^{• • • •} (5)

In contrast to the conventional wind power generators wherein out of a total enthalpy of the wind, only the kinetic energy is used, the wind power generator 10 (Fig. l) according to the present invention can utilize both the kinetic energy and the static enthalpy of the wind. This is because by using the adiabatic expansion of air caused by the front stator 41, the wind velocity a temperature difference (T₁-T₂) shown in Equation (4) so that the static enthalpy is converted into kinetic energy, which is added to the original kinetic energy. By thus using both the kinetic energy and the static enthalpy of the wind, the rotor 46 is able to achieve greater work than as done in the conventional wind power generators.

As thus far described, the wind power generator 10 according to a first embodiment of the present invention comprises a duct 23 having an air inlet 37, an air outlet, a convergent nozzle part 23A defining a converging airflow passage extending from the air inlet 37 toward the air outlet, and a divergent diffuser part 23B contiguous with the nozzle part 23A and defining a divergent airflow passage extending contiguously from a downstream end of the convergent airflow passage to the air outlet 38, a rotary shaft 44 rotatably supported in the duct 23 by a support member extending from an inner surface of the duct 23, a rotor 46 attached to the rotary shaft 44, and an electric generator 51 driven by rotation of the rotor 46, wherein the diffuser part 23B has a plurality of slots 36 formed therein, and the slots 36 are formed by and between adjacent edges of a plurality of wing elements 26 to 29 arranged in an axial direction of duct 23 such that the adjacent edges 26b and 27a, 27b and 28a, 28b and 29a of the wing elements overlap each other in the axial direction of the duct 23. The support member is formed by the front stator 41, rear stator 42, front nacelle 56 and rear nacelle 76

By virtue of the slits 36, it is possible to supply energy to the stream of air inside the diffuser part 23B of the duct 23 to thereby recover the pressure inside the diffuser part 23B to the extent that separation of airflow from an inner surface of duct 23 does not occur. Furthermore, by virtue of the overlapping arrangement of the adjacent edges 26b and 27a, 27b and 28a, 28b and 29a of the wing elements 26-29, the slots 36 are relatively small in length and hence able to guide the outside air into a given direction with little pressure loss involved as the outside air is introduced into the duct 23. This makes it possible to increase the amount of energy supplied into the diffuser part 23B of the duct 23, which will increase the velocity of air flowing into the duct 23 and hence enables the rotor 46 to rotate at high speeds, leading to increased power output of the wind power generator 10. The overlapping arrangement of the wing elements 26-29 further provides cost reduction as the slots 36 can be formed easily without requiring precise machining operation.

Furthermore, by virtue of the wing elements 26-29 arranged in overlapping relation in the axial direction of the duct 23, at least the diffuser part 23B of the duct is readily adaptable to design modification without requiring replacement of the entire duct 23.

In the illustrated preferred embodiment, each of the wing elements 26-29 is formed by a divergent annular ring member, and the plurality of wing elements 26-29 jointly forms at least the diffuser part 23B of the duct 23. The diffuser part 23B thus formed by a plurality of divergent annular ring members 26-29 arranged in the axial direction of the duct is easy to maintain and readily adaptable to design modification.

The wind power generator 10 further comprises a first stator (front stator) 41 disposed upstream of the rotor 46 for deflecting a stream of air coming to the rotor 46 toward a rotating direction of the rotor 46. The first stator 41 is simple in construction but readily possible to change the inflow angle of air coming to the rotor 46. By thus providing the first stator 41, it is possible not only to reduce the number of parts of the wind power generator 10 for cost-saving, but also to increase the momentum of air in the rotating direction of the rotor 46 for increasing power output of the wind power generator 10. The first stator 41 increases the inflow velocity of the air coming to the rotor 46 with the result that the rotor 46 can rotate at high speeds, leading to increased power output of the wind power generator 10. The wind power generator 10 further comprises a second stator (rear stator 42) disposed downstream of the rotor 46 for rectifying a stream of air flowing backward of the rear stator 52. The first stator 41 has a deflection angle, the rotor 46 has a deflection angle, and the deflection angle of the first stator 41 and the deflection angle of the rotor 46 are equal in absolute value to each other. With this arrangement, since the outflow angle of air leaving from the rotor 46 corresponds to the inflow angle of air coming to the first stator 41, the air is allowed to leave the rotor 46 in a direction parallel to the axis of rotation of the rotor 46 and rectifies the wake of the rotor 46. As a result, the flow velocity of air coming into the duct 23 increases to thereby enable the rotor 46 to rotate at high speeds and increase power output of the wind power generator 10. Fig. 5 shows in cross section a duct-equipped wind power generator according to a second embodiment of the present invention. In Fig. 5, these parts, which are the same or identical to those shown in Fig. 1, are designated by the same reference characters and no further description thereof is necessary. As shown in Fig. 5, the wind power generator 200 comprises support members 212a, 212b and 212C attached to a mounting base 201, and a wind power generator unit 213 supported by the support members 212a to 212c in a horizontal position.

The wind power generator unit 213 includes a duct 223, a wind power generator body 224 disposed in the duct 223, and front and rear stators 41 and 42, which serve also as connecting members connecting the duct 223 and the wind power generator body 224.

The duct 223 includes a front duct 231 supported by the support members 212a, 212b and a rear duct 232 disposed behind the front duct 231 and supported by the support member 212c. The duct 223 has an air inlet 237 at a leading edge of the front duct 231 and an air outlet 238 at a trailing edge of the rear duct 232. The front duct 231 has a front portion formed into a constricted nozzle part 223A of convergent channel-shaped configuration having a cross-sectional area reducing gradually in a direction from the air inlet 237 toward the air outlet 238, and a main portion extending continuously and rearward from the nozzle part 223A and formed into a diffuser part 223B of divergent channel-shaped configuration having a cross-sectional area gradually increasing toward a trailing edge opening 231b of the front duct 231. The rear duct 232 forms a rear part of the diffuser part 223B and has a front edge opening 232a facing the trailing edge opening 231b of the front duct 231. The power generator body 224 generally comprises a nacelle 243 forming a fuselage mounted inside the duct 223 via the front stator 41 and the rear stator 42, a horizontal rotary shaft 44 rotatably mounted in a front half of the nacelle 243, a rotor 46 mounted to the horizontal rotary shaft 44 for rotation therewith, an output shaft 247 rotatably mounted in a rear half of the nacelles 243, a speed-up gear 48 coupled to a rear end of the horizontal rotary shaft 44 and a front end of the output shaft 247, an electric generator 51 disposed on a rear end portion of the output shaft 247, and a tip turbine- equipped rotor 252 mounted to a rear end of the output shaft 47. The tip-turbine equipped rotor 252 forms a main part of an external energy- addition means or mechanism, which is disposed downstream of the rotor 46 and drivable by auxiliary power.

The front stator 41 is formed by a plurality of stator blades 61 forming wings, which change the direction of wind toward the rotor 46 so that the wind flowing into the duct 223 will impinge on the rotor 46, and which serve also as a support member for supporting the wind power generator body 224 relative to the duct 223. The stator blades 46 are connected at one end to the duct 223 via an intermediate plate or bracket 63 by means of flat head screws 64 and, at the other end, to a front nacelle 66 by means of flat head screws 67. The front nacelle 66 forms a part of the nacelle 243.

The rear stator 42 is formed by a plurality of stator blades 71 forming wings, which rectify the stream of wind flowing backward of the rear stator 42, and which serve also as a support member for supporting the wind power generator body 224 relative to the duct 223. The stator blades 71 are connected at one end to the duct 223 via an intermediate plate or bracket 73 by means of flat head screws 74 and, at the other end, to a rear nacelle 276 by means of flat head screws 77. The rear nacelle 276 forms a part of the nacelle 43. The nacelle 243 is constituted by the front nacelle 66 and the rear nacelle 276. The front nacelle 66 retains therein a ball bearing 81 by means of which the horizontal rotary shaft 44 is rotatably supported. Reference numeral 83 denotes a cap attached to a front end of the front nacelle 66 for rectifying the stream of wind coming to the duct 223 The rear nacelle 76 has a two-piece structure composed of a front body

85 and a rear body 86 that are fitted together end to end. The front nacelle body 85 retains therein a ball bearing 87 by means of which a front end portion of the output shaft 247 is rotatably supported. The rear nacelle body 86 is provided with a coil support portion 92, which supports a coil 91 and retains a ball bearing 93 by means of which a rear end of the output shaft 247 is rotatably supported.

The speed-up gear 48 has a sun gear 116 connected by spline-coupling to the front end of the output shaft 247. With the speed-up gear 48 thus provided, rotation of the horizontal rotary shaft 44 is transmitted at an increased speed to the output shaft 247.

The tip turbine-equipped rotor 252 includes a support shaft 124 threadedly connected to an externally threaded portion 247a of the small- diameter portion 121 of the output shaft 247, a cylindrical blade support portion 126 rotatably mounted on the support shaft 124 via a pair of axially spaced ball bearings 125 and 125, a rotor body 128 attached by flat head screws 247b to the blade support portion 126, and a tip turbine 129 attached to an outer peripheral portion of the rotor body 128. Reference numeral 247c denotes a lock nut, which is threadedly secured to the externally threaded portion 247a of the output shaft 247 to lock the support shaft 124 in position against loosening.

The duct 223, bearings 125, blade support portion 126 and rotor body 128 of the tip turbine-equipped rotor 52 together form a compressor 130. Among these components, the rotor 52 forms a main part of the compressor 130. The compressor 130 forms an external energy- addition means or mechanism.

The rotor body 128 has a plurality of rotor blades 128a. Each of the rotor blades 128a is equipped with a tip 129a of wing-like configuration, which forms together with the remaining tips 129a the tip turbine 129. The tip turbine 129 projects radially outward from the duct 223 through a space defined between the trailing edge opening 231b of the front duct 231 and the front edge opening 232a of the rear duct 232. Reference numeral 129b denotes a bolt formed integrally with a distal end of each tip 129a, and reference numeral 129c denotes a nut threadedly with the bolt 129b to attach the tip 129a to an outer end of each rotor blade 129.

With the tip turbine 129 arranged to project from the duct 223, the tip turbine 129 rotates with the wind flowing outside the duct 223 to thereby rotate the rotor body 128. As a consequence, wake flow occurring downstream from the rotor body 128 increases in pressure to thereby increase the speed of wind flowing into the duct 223.

The wind power generator 200 of the foregoing construction operates in tlie same manner as discussed above with reference to Figs. 2(a)-2(b), 3(a)-3(e) and 4(a)-4(b) with the exception that circled number 5 shown in Fig. 4(a) denotes the position of the tip turbine- equipped rotor 252, which forms a main part of the compressor 130. At the position of circled number 5 shown in Fig. 4(a), the compressor 130 constituted by the tip turbine-equipped rotor 252 compresses the air inside the duct 223 to thereby inject energy to the wake flow of the tip turbine-equipped rotor 252. At the same time, operation of the divergent channel-shaped diffuser part 223B of the duct 223 is combined with the compressing operation by the tip turbine-equipped rotor 252 with the result that the wake flow of the tip turbine-equipped rotor 252 recovers the pressure, which will then become equal to or greater than Po at the position of circled number 6. In this instance, if the pressure P is greater than Po, it will fall to Po at the position downstream of the duct 23.

Correspondingly, as the wind flows from the position of circled number 4 through the position of circled number 5 to the position of circled number 6, by virtue of the pressure recovery achieved by a combination of diffusing operations of the divergent channel-shaped diffuser part 223B of the duct 223 and energy injecting operation of the compressor 130, the enthalpy increases progressively to the extent that at the position of number 6, the pressure Pβ is equal to or greater than the pressure Po at the position of number 0.

In the wind power generator 200 of the second embodiment discussed above, the compressor (external energy- addition means) 130 operates to exert energy to the airflow downstream from the rotor 46 to thereby increase the pressure in the duct 223 at the downstream side of the rotor 46. With this pressure increase, the pressure inside the diffuser part 223B recovers soon so that separation of airflow from an inside surface of the duct 223 does not occur. As a result, the flow velocity of air coming into the duct 223 increases to thereby enable the rotor 46 to rotate at high speeds, leading to improved power output of the wind power generator 200.

Fig. 6 shows in cross section a wind power generator according to a third embodiment of the present invention. In Fig. 6, these parts, which are the same or identical to those shown in Fig. 1, are designated by the same reference characters and no further description thereof is necessary.

As shown in Fig. 6, the wind power generator 300 comprises a support base 12 attached to a mount table or base 11, and a wind power generator unit

323 supported by the support base 12 in such a manner that the wind power generator unit 313 is rotatable in a horizontal plane to align itself to the direction of wind at all times.

The wind power generator unit 313 includes a duct 323, a wind power generator body 24 disposed in the duct 323, and front and rear stators 41 and

42, which serve also as connecting members connecting the duct 323 and the wind power generator body 324. The duct 323 has an air inlet 337 and an air outlet 338.

The duct 323 has a front portion formed into a constricted nozzle part 323A of convergent channel-shaped configuration having a cross-sectional area reducing gradually in a direction from the air inlet 337 toward the air outlet 338, and a main portion extending continuously and rearward from the nozzle part 323A and formed into a diffuser part 323B of divergent channel-shaped configuration having a cross-sectional area gradually increasing toward the outlet opening 338 of the duct 323.

The wind power generator 300 further includes a plurality of heating devices 325 mounted on a support member 326 attached to an inner surface of the diffuser part 323B of the duct 323 so that the heating devices 325 are disposed downstream of the rotor 46 for heating a stream of air flowing downstreain of the rotor 46. The heating devices 323 form an external energy- addition means for exerting an external energy (thermal energy in this embodiment) to the stream of air flowing downstream of the rotor 46. The heating devices 325 may comprise a heat pump or an electric heater. By the heating devices 325 thus the stream of air, which has left the rotor with reduced pressure, can readily recover its initial pressure before it reaches the air outlet 338.

The front stator 41 serves in double as a deflector for directing the inflow air toward the rotor 46, and also as a support member for supporting the wind power generator body 24 relative to the duct 323. The front stator 41 is connected at an outer end to the duct 323 via an intermediate plate or bracket 63 by means of flat head screws 64 and, at an inner end, to a front nacelle 66 by means of flat head screws 67.

Similarly, the rear stator 42 operates to rectify the stream of wind flowing backward of the rear stator 42 and also serves as a support member for supporting the wind power generator body 24 relative to the duct 323. The rear stator blades 42 is connected at an outer end to the duct 323 via an intermediate plate or bracket 73 by means of flat head screws 74 and, at an inner end, to a rear nacelle 76 by means of flat head screws 77. Reference numeral 83 denotes a cap attached to a front end of the front nacelle 66 for rectifying the stream of wind coming to the duct 323

As thus far described, the wind power generator 300 according to the third embodiment of the present invention comprises^ a duct 323 having an air inlet 337, an air outlet 338, a convergent nozzle part 323A defining a converging airflow passage extending from the air inlet 337 toward the air outlet 338, and a divergent diffuser part 323B contiguous with the nozzle part 323A and defining a divergent airflow passage extending contiguously from a downstream end of the convergent airflow passage to the air outlet 338; a rotary shaft 44 rotatably supported in the duct 323 by a support member extending from an inner surface of the duct 323; a rotor 46 attached to the rotary shaft 44; an electric generator 51 driven by rotation of the rotor 46; and an external energy- addition means disposed in the diffuser part 323B for exerting an external energy to a stream of air flowing downstream of the rotor, 46 wherein the external energy- adding means comprises a heating device 325. The heating device 325 may be a heat pump or an electric heater.

With the heating device 325 thus provide as an external energy- addition means, the air as it flows along the diffuser is heated so that the air inside the diffuser part 323B recovers its initial pressure (inflow pressure) before it reaches the air outlet 338. It is therefore possible to increaser the velocity of air flowing into the duct 323, leading to high speed rotation of the rotor 46 with a resulting increase in power output of the wing power generator 300.

In the embodiment shown in Fig. 6, the heating devices 325 are disposed downstream of the rear stator 42. The invention is not limited to the illustrated embodiment but may include an arrangement in which the heating devices 325 are disposed between the rotor 46 and the rear stator 42. Industrial Applicability

With the arrangements so far described, the present invention can be used advantageously as a small-sized wind power generator that can be installed independent from the commercial power supply.

Claims

1. A wind power generator comprising: a duct having an air inlet at a first end thereof and an air outlet at a second end opposite to the first end, the duct further having a convergent nozzle part defining a converging airflow passage extending from the air inlet toward the air outlet, and a divergent diffuser part contiguous with the nozzle part and defining a divergent airflow passage extending contiguously from a downstream end of the convergent airflow passage to the air outlet; a rotary shaft rotatably supported in the duct by a support member extending from an inner surface of the duct; a rotor attached to the rotary shaft; and an electric generator driven by rotation of the rotor, wherein the diffuser part has a plurality of slots formed therein, and the slots are formed by and between adjacent edges of a plurality of wing elements arranged in an axial direction of duct such that the adjacent edges of the wing elements overlap each other in the axial direction of the duct.

2. The wind power generator according to claim 1, wherein each of the wing elements is formed by a divergent annular ring member, and the plurality of wing elements jointly forms at least the diffuser part of the duct.

3. The wind power generator according to claim 1, further comprising a stator disposed upstream of the rotor for deflecting a stream of air coming to the rotor toward a rotating direction of the rotor.

4. The wind power generator according to claim 3, wherein the stator increases the inflow velocity of the air coining to the rotor.

5. The wind power generator according to claim 3, wherein the stator has a deflection angle, the rotor has a deflection angle, and the deflection angle of the stator and the deflection angle of the rotor are equal in absolute value to each other.

6. The wind power generator according to claim 1, further comprising a first stator disposed upstream of the rotor for deflecting a stream of air coming to the rotor toward a rotating direction of first rotor, and a second stator disposed downstream of the rotor for rectifying a stream of air flowing backward of the second stator.

7. The wind power generator according to claim 6, wherein the first stator increases the inflow velocity of the air coming to the rotor.

8. The wind power generator according to claim 6, wherein the first stator has a deflection angle, the rotor has a deflection angle, and the deflection angle of the first stator and the deflection angle of the rotor are equal in absolute value to each other.

9. A wind power generator comprising^'- a duct having an air inlet at a first end thereof and an air outlet at a second end opposite to the first end, the duct further having a convergent nozzle part defining a converging airflow passage extending from the air inlet toward the air outlet, and a divergent diffuser part contiguous with the nozzle part and defining a divergent airflow passage extending contiguously from a downstream end of the convergent airflow passage to the air outlet; a rotary shaft rotatably supported in the duct by a support member extending from an inner surface of the duct; a rotor attached to the rotary shaft; an electric generator driven by rotation of the rotor; and an external energy- addition means disposed in the diffuser part for exerting an external energy to a stream of air flowing downstream of the rotor, wherein the external energy-adding means comprises a heating device.

10. The wind power generator according to claim 9, wherein the heating device comprises a heat pump.

11. The wind power generator according to claim 9, wherein the heating device comprises an electric heater.

12. The wind power generator according to claim 9, further comprising a stator disposed upstream of the rotor for deflecting a stream of air coming to the rotor toward a rotating direction of the rotor.

13. The wind power generator according to claim 12, wherein the stator increases the inflow velocity of the air coming to the rotor.

14. The wind power generator according to claim 12 wherein the stator has a deflection angle, the rotor has a deflection angle, and the deflection angle of the stator and the deflection angle of the rotor are equal in absolute value to each other.

15. The wind power generator according to claim 9, further comprising a first stator disposed upstream of the rotor for deflecting a stream of air coming to the rotor toward a rotating direction of first rotor, and a second stator disposed downstream of the rotor for rectifying a stream of air flowing backward of the second stator.

16. The wind power generator according to claim 15, wherein the first stator increases the inflow velocity of the air coming to the rotor.

17. The wind power generator according to claim 15, wherein the first stator has a deflection angle, the rotor has a deflection angle, and the deflection angle of the first stator and the deflection angle of the rotor are equal in absolute value to each other.