专利汇可以提供WIND TURBINE GENERATOR专利检索,专利查询,专利分析的服务。并且It is an object of the present invention to provide a tandem rotor type wind turbine generator capable of enhancing an efficiency of power generation. In the wind turbine generator, a front wind rotor (1) coupled to an armature rotor (4) of a power generator (3) includes a blade (6) designed, in an area outer than an intermediate of a rotation radius of the front wind rotor (1), to have a blade element comprised of an aerofoil being cambered in a cross-section along a rotational direction thereof so as to ensure a desired rotation torque, and is radially twisted so as to ensure an angle of attack smaller by a predetermined stable margin angle than an angle of attack providing a maximum lift-drag ratio regardless of a radial position, and further designed, in an area inner than the intermediate of a rotation radius of the front wind rotor, to be radially twisted so as to ensure an angle of attack at which a drag acting on the blade element is made small, and a total force of the drag and a lift force is axially directed, regardless of a radial position, in order to ensure a no-load condition.,下面是WIND TURBINE GENERATOR专利的具体信息内容。
The invention relates to a tandem rotor type wind turbine generator which makes it possible to enhance an efficiency of power generation.
A new type wind turbine generator, where the large and the small sized wind rotors drive respectively the inner and the outer armatures of the peculiar generator having no traditional stator, was proposed by the inventor of the present application to overcome the problems found in the existing wind turbine generators which are just an extension of conventional wind turbine generators suitable to Europe and U.S.A. both having good wind conditions, enable the wind turbine generator to be suitable to varied wind conditions, and to improve the performance, and was already patented (see Patent Document 1).
The tandem rotor type wind power unit is characterized by rotational behavior of the tandem wind rotors, where the rotational directions and speed are unsettled while the rotational torque acting on the armature rotor 4 coincides with the same acting on the field rotor 5 of the generator 3. The wind power unit is not equipped with any accelerators, and the front and the rear wind rotor shafts are connected to the armature rotor 4 and the field rotor 5 of the power generator 3, respectively. Then, the rotational speeds and directions of the wind rotors are defined as follows in response to the wind velocity, while the rotational torques acting on the armature rotor 4 and the field rotor 5 are equal to each other, that is, the front wind rotor 1 and the rear wind rotor 2 work at the same rotational torque (but in opposite directions), as mentioned above. As shown in
As a reference discussing the optimum number of the blades in the wind power unit, there is the non-patent document 1 having been reported by the inventor of the present application.
In the case of the flat blades with simply a rectangular profile [the thickness = 1.5 mm, (the diameter of the rear wind rotor)/(the diameter of the front wind rotor 500 mm) = DRF = 0.71], the effects of the blade number ZF and ZR of the front and the rear wind rotors on the turbine performances are shown in
That is, as mentioned above, the rear wind rotor must counter-rotate against the front wind rotor at the comparatively lower rotational torque (the counter-rotation, in the operation from the extremely slow wind velocity to the moderately higher wind velocity than the rated wind velocity), and start rotating the same direction as the front wind rotor with the increase of the rotational torque (the same-directional rotation, in the operation at the higher wind velocity). Though the number of blades in the front wind rotor scarcely affects the rotational torque and the output, in the case of ZF= 2, the rear wind rotor is not expected to accomplish the same-directional rotation as the front wind rotor on which the present concept is based. Judging resultantly from the output power and so on, ZF = 3 is desirable in the same way as the traditional single rotor wind turbine generator [
Rearrangement of
The optimal diameter ratio and the optimal axial distance between the front and the rear wind rotors are discussed in the non-patent documents 2 and 3 which have also been reported by the inventor of the present application.
In order to optimize the diameter ratio and the axial distance, two blade profiles were prepared (a diameter of the front wind rotor is 500 mm). One is a two-dimensional blade E formed with the symmetrical aerofoil without the camber (
The traditional wind turbine generators are based on the technologies regarding single stage propeller, and suitable to Europe and U.S.A. where a good/rich wind condition can be obtained for power generation, and has the following technical problems to be solved.
It is considered, in the future, that an area suitable to the traditional wind turbine generator, which arbitrarily chooses the wind condition may reduce, and then the wind power unit providing the high output irrespective of the wind condition will be provided for the power generation.
The desirable profiles of the wind power unit, which can solve the problems mentioned above, are to (1) increase the output even at a low wind velocity, (2) lower the specified wind velocity at which the rated operation mode starts, and (3) take out accelerators, brakes, pitch control mechanism, and so on. The above-mentioned patented tandem rotor type wind power unit satisfies all of these requirements necessary for practical use.
However, as long as we keep the traditional research/development policies modifying/improving the single stage wind rotor based on aerodynamics, it may be impossible to expect dramatically advanced technologies beyond the present level. Then, new technologies have been proposed in a standpoint of the views different from the concepts of the inventor of the present application.
As a typical example, there is "Wind Lens" proposed by Toshiaki Ota et al. (see Japanese Patent Application Publication No.
The present invention relates to a wind rotor employed in the tandem rotor type wind power unit presented above. The inventor of the present application has developed a counter-rotating type hydroelectric unit composed of two-stage runners (impellers) and an inner/outer double rotational type generator. This hydroelectric unit, however, quite differs from the wind power unit proposed here, as follows.
As mentioned above, since the flow interactions between the front and the rear wind rotors is intensive and the traditional design process for the single rotor type wind turbine generator cannot be applied to the tandem rotor type wind turbine generator. Hence, it is desired to establish a new design process.
It is an object of the present invention to provide a tandem rotor type wind turbine generator capable of enhancing an efficiency of power generation.
In order to achieve the above-mentioned object, in the first aspect of the present invention, there is provided a wind turbine generator including a front wind rotor and a rear wind rotor arranged coaxially with each other, one of the wind rotors being connected to a rotatable armature rotor of a generator and the other being connected to a rotatable field rotor of the generator, the direction in which a blade of the front wind rotor is twisted being in the axially opposite direction to a direction in which a blade of the rear wind rotor is twisted, characterized in that a rotation radius of said rear wind rotor is designed to be smaller than a rotation radius of said front wind rotor, but longer than a half of the same, the front wind rotor includes a blade designed, in an area outer than an intermediate of a rotation radius of the front wind rotor, to have a blade element comprised of an aerofoil being cambered in a cross-section along a rotational direction thereof so as to ensure an expected rotational torque, and is radially twisted so as to ensure an angle of attack smaller by a predetermined stable margin angle than an angle of attack providing a maximum lift-drag ratio regardless of a radial position, the blade of the front wind rotor is designed, in an area inner than the intermediate of a rotation radius of of the front wind rotor, to be radially twisted so as to ensure an angle of attack at which a drag acting on the blade element is made small, and a total force of the drag and a lift force is axially directed, regardless of a radial position, in order to ensure a no-load condition.
As mentioned just above, the blade of the front wind rotor with the large diameter is designed to not only get the no-load condition but also reduce the drag force as possible at the smaller radius (namely the hub side) where the rotational torque makes hardly any contribution to the rotation. Such a blade scarcely works and passes directly/wholly the upstream wind energy to the rear wind rotor as it is at the small radius, and then ensures resultantly the effective can efficiently absorb energy absorption as the tandem wind rotors. Herein, "a maximum lift-drag ratio" means a lift-drag ratio providing a maximum value in a lift-drag curve against the angle of attack.
In the second aspect of the present invention, the rear blade mentioned above is designed to include a blade element comprised of an aerofoil being cambered in a cross-section along a rotational direction thereof so as to ensure an expeced rotational torque, the rear wind rotor is radially twisted in an area corresponding to the area outer than an intermediate of a rotaion radius of the front wind rotor, so as to ensure an angle of attack smaller by a predetermined stable margin angle than an angle of attack providing a maximum lift-drag ratio to a swirling flow discharged from the front wind rotor, and the rear wind rotor is radially twisted in an area corresponding to the area inner than an intermediate of a rotation radius of the front wind rotor, so as to ensure an angle of attack smaller by a predetermined stable margin angle than an angle of attack providing a maximum lift-drag ratio against axial flow having no swirling components.
By designing the rear wind rotor with the appropriate blade presented just above, the rear wind rotor can efficiently absorb the wind energy in a whole range, and contributes to increase the output power as the tandem wind rotors.
In the third aspect of the present invention, the front wind rotor and the rear wind rotor are set close to each other, the front wind rotor has three blades, and the rear wind rotor has four to six blades.
Such configurations enable the wind power unit to operate at the ideal conditions. That is, the rear wind rotor starts rotating in the opposite direction against the rotational direction of the front wind rotor at the breeze. The rotational speed of the rear wind rotor accelerates gradually and decelerates after reaching the maximum speed, with the increase of the wind velocity. While wind velocity further increases, the rear wind rotor stops once, and then, starts rotating in the same direction as the rotational direction of the front wind rotor.
In the fourth aspect of the present invention, the rear wind rotor is characterized to have a radius about 0.84 times smaller than a radius of the front wind rotor.
This accomplishes counter-directional rotation, stopping and common-directional rotation of the rear wind rotor together with achievement of a maximum efficiency.
In the fifth aspect of the present invention, the predetermined margin angle for operating the rotor at the stable condition is characterized to be in the range of 2 to 5 degrees both inclusive.
Thus, it is possible to maintain stability in operating the wind power unit turbine generator.
In the sixth aspect of the present invention, the intermediate in the front wind rotor is located at 40 to 60% both inclusive of a radius of gyration of the front wind rotor.
Thus, it is possible to effectively transfer the wind energy existing in an inner area of the front wind rotor, to the rear wind rotor.
In accordance with the present invention, the blade of the front wind rotor is formed by the cambered aerofoil at larger than the intermediate radius of the rotor so as to get the rotational torque expected, and is given radially the twist so as to take the angle of attack smaller by a predetermined margin angle for operating the rotor at the stable condition than the angle of attack providing the maximum lift-drag ratio regardless of the radius, and the blade at smaller than the intermediate radius of the front wind rotor is radially twisted so as to take the no-load condition regardless of the radius by not only turning the resultant force combined the lift with the drag forces in the axial direction but also reduce-the drag acting on the blade element as possible. By such a present invention, it is possible to accomplish efficient wind energy conversion, and behave sufficiently the characterized performances the tandem rotor type wind turbine generator.
An embodiment in accordance with the present invention will be explained hereinbelow with reference to drawings.
An example of the desirable blade profiles in the front wind rotor (front blade H) is shown in
The configurations of the tandem wind rotors suitable for embodying the present invention are as follows.
Dimensions shown in
The blade of the front wind rotor is formed by the cambered aerofoil at the blade tip side, where the radius "r" is larger than 40-60% of the front wind rotor radius (about 50%: the guidance in the present embodiment), and is given radially the twist so as to take the angle of attack "α" smaller by a predetermined margin angle for operating the rotor at the stable condition than the angle of attack providing the maximum lift-drag ratio regardless of a radial position (hereinbelow, "α" is not the angle providing the maximum lift-drag ratio, but the angle of attack smaller by the predetermined margin angle than the angle of attack providing the maximum lift-drag ratio). The velocity triangles around the blade element at the arbitrary radius in the tip side are shown in
The wind rotor rotates by the component FT in the rotational direction of the resultant force "F" induced from the drag force "D" parallel to the vector average of the outlet/inlet relative velocities "w2" and "w1", and the lift force "L" perpendicular to the drag force "D". Accordingly, the larger lift-drag ratio (ε = L/D) is, the higher the component FT in the rotational direction of the resultant force "F", that is, the output power is. For instance, in MEL002 aerofoil proposed by National Institute of Advanced Industrial Science and Technology the lift-drag ratio is maximized when the angle α of attack is equal to about 10 degrees. In order to keep the angle α of attack to be equal to 10 degrees regardless of a radius, with reference to the velocity triangles shown in
A lift force L and a drag force D, that is, a lift-drag ratio (ε = L/D) is affected by the blade profile. These forces are not uniform (not defined by a certain formulation), and hence, have to be get by the performance tests or the numerical flow simulation.
As confirmed with
For the above-mentioned reasons, an actually designed angle of attack is set smaller by predetermined margin angle for operating the rotor at the stable condition than the angle of attack providing the maximum lift-drag ratio, to make the operating range at the stable condition wide. How many degrees the angle of attack is set smaller is dependent on a design concept of the a manufacturer or an engineer, but the predetermined margin angle is 2 to 5 degrees in general, and the angle is about 3 degrees in the present embodiment.
The blade of the front wind rotor in the present invention is characterized by the profile at the hub side of the smaller radius (inner area: 60-40 % of the rotation radius [ = (the rotation radius - the radius of the outer area)/(the a-rotation radius)], about 50 % in the present embodiment), which scarcely contributes to the rotational torque in a large-diameter wind rotor. That is, accomplishing no load condition by adopting a blade element whose drag force is as small as possible, the front wind rotor does not work at the smaller radius and passes the upstream wind energy as it is to the rear wind rotor. As shown in
No angular momentum change at both inlet and outlet of the wind rotor means that no force (FT = 0) acts on a blade element in the rotational direction (circumferential direction). That is, as shown in
The relative flow angle β measured from the rotational direction is given as follows.
Accordingly, the direction of the blade element (aerofoil) at any point of the radius may be determined (twisting a blade), such that the angle α of attack taking the lift-drag ratio ε given by the equation (1) for the relative flow angle β given by the equation (2). At this design condition, since the resultant force "F" causes the momentum change in an axial direction, namely the decrease of the velocity in an axial direction, the blade element which provides a possibly smaller resultant force "F" namely the drag force "D" is selected. Though
As mentioned above, the output can be increased by assigning the rear wind rotor, the energy absorption at the smaller radius where the large-diameter front wind rotor is, is not expected to effectively absorb the wind energy. For instance, the rotation torque generated from the front wind rotor G with the diameter dF of 500 mm is 0.1136 Nm at 50% of the tip side and is 0.0096 Nm at 50% of the hub side, in the vicinity of the maximum output operation. Thus, it can be confirmed that the contribution of the rotational torque generated at the hub side is quite small in terms of output (= rotation torque × rotational angular velocity).
The tandem window rotors are not constructed merely by combining optimal single wind rotors with each other, but should be designed so that the front wind rotor having the blade which does not absorb wind energy at the smaller radius, as mentioned above. The rear wind rotor is designed to match the flow condition from the front wind rotor, as follows.
The rear is formed with the cambered aerofoil so as to take the expected rotational torque regardless of the radius. Then, the rear blade is twisted radially to take the angle of attack smaller by a predetermined margin angle for operating the rotor at the stable condition than the angle of attack providing the a-maximum lift-drag ratio against the swirling flow discharged from the front wind rotor, at the larger radius than the intermediate radius of the front wind rotor. As for the rear blade profile at the smaller radius than the intermediate radius of the front wind rotor, the blade is also radially twisted so as to make the angle of attack smaller by a predetermined margin angle for operating the rotor at the stable condition than the an angle of attack providing the maximum lift-drag ratio against the axial flow without the swirling component.
Since the front blade H does not work at the smaller radius, the output coefficient CPR decreases in comparison with other wind rotors (the maximum output coefficient of the front blade H is 0.160, whereas the coefficient of the front blade G is 0.175). However, the front blade H can significantly enhance the output of the rear wind rotor (the maximum output coefficient of the rear blade G with the front blade G being used is 0.138, whereas the maximum output coefficient of the rear blade G with the front blade H being used is 0.165). Resultantly, the output as the tandem rotor type wind turbine generator is increased (
The present invention is applicable, as a wind turbine generator providing the higher output, to various fields such as a wind turbine generating industry, a machinery industry, an electricity industry, and an electric power industry which aim at generating clean energy.
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