A vertical axis wind turbine noise reduction device

Abstract

The present application relates to the technical field of wind power generator noise reduction device, especially to a vertical axis wind power generator noise reduction device, comprising a impeller assembly and a annular fairing coaxially covering the impeller assembly; the annular fairing is formed by a plurality of guide vanes and has a semi-closed ring structure with a wide top and a narrow bottom; the guide vanes are uniformly arranged along the circumferential direction of the annular fairing; the windward side of the guide vanes is the windward side along the radial direction of the annular fairing, and the windward side along the radial direction of the annular fairing is the wind guide side; the included angle between the windward side and the vertical direction is 6°-12°; the tangential angle between the connecting line of the windward side and the wind guide side and the outer circumferential surface of the annular fairing is 25°-55°. The present application relates to the field of wind power generation equipment, especially to a vertical axis wind power generator noise reduction device, which can significantly reduce the noise generated during the operation of the generator.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind turbine noise reduction device technology, in particular to a vertical axis wind turbine noise reduction device. BACKGROUND

[0002] The existing vertical axis wind turbine is one of the wind energy utilization equipment, the rotating shaft of which is perpendicular to the ground, and the impeller rotates around the vertical shaft, which usually consists of core components such as blades, main shaft, support structure and generator.

[0003] The existing vertical axis wind turbine has the following technical problems: the blades produce strong disturbance with the airflow during rotation, especially in urban, roof, community and other distributed scenarios, the aerodynamic noise and mechanical noise are obvious; the existing structure is mostly bare impeller, without effective airflow rectification and noise reduction measures; when the airflow enters the impeller area, part of the wind energy is not fully captured, causing energy loss, and there is also the problem of low wind energy utilization rate.

[0004] Therefore, it is necessary to design a vertical axis fan structure that can improve wind energy utilization rate and significantly reduce noise. SUMMARY

[0005] The present application relates to the field of wind power generation equipment, in particular to a vertical axis wind turbine noise reduction device, which can significantly reduce the noise generated during operation of the generator.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme: a vertical axis wind turbine noise reduction device, comprising an impeller assembly and a ring-shaped fairing cover coaxially covering the outside of the impeller assembly.

[0007] The ring-shaped fairing cover is formed by a plurality of guide vanes and has a semi-closed ring structure that is wide at the top and narrow at the bottom; the guide vanes are uniformly arranged along the circumferential direction of the ring-shaped fairing cover; the windward side of the guide vane is outward along the radial direction of the ring-shaped fairing cover, and the windward side is inward along the radial direction of the ring-shaped fairing cover.

[0008] The included angle between the windward side and the vertical direction is 6°~12°;

[0009] The tangent angle between the connecting line of the windward side and the windward side and the outer peripheral surface of the ring-shaped fairing cover is 25°~55°.

[0010] The present application sets the side of the cover of the annular fairing to be inclined, and there is a tangential angle between the guide vane and the outer peripheral surface of the annular fairing, the inclined surface generates axial tangential coupling on the fluid, and the tangential arrangement of the guide vane can guide the airflow at the cover wall to be a flow with both axial component and tangential component, generate a continuous axial component, and then the tangential force gives the fluid angular momentum, so that the fluid can rotate around the axis and generate a low pressure gradient in the axial direction, the low pressure pulls the upward component in the axial direction, forms an upward rotating flow, and finally forms a rotating flow spirally rising around the central axis around the cover body, which can effectively comb the airflow, reduce the noise source of vortex shedding and guide the sound wave energy to high altitude, thereby realizing the noise reduction effect.

[0011] In order to further improve the noise reduction effect, the projection surface formed by the projection line between the two adjacent guide vanes and the axis of the annular fairing is respectively a first projection surface and a second projection surface, and there is an overlapping surface between the first projection surface and the second projection surface.

[0012] The above structure makes the annular fairing axis and the outside have no noise leakage gap, and the noise generated in the annular fairing can be collected and led out along the upper end opening of the annular fairing, thereby further improving the noise reduction effect.

[0013] In order to improve the wind energy utilization rate, the included angle between the connection line of the windward edge and the wind guide edge of the two adjacent guide vanes is 10°-20°. The guide vanes are arranged at an included angle to form a tapered flow channel. Based on the law of conservation of mass and Bernoulli's principle, the airflow forms an orderly accelerated flow, and the guide vanes work together to convert the axial airflow into a spiral upward rotating flow around the axis. Not only can the vortex noise be reduced by combing the main flow, but also the sound wave propagation path can be changed by means of airflow guidance, thereby realizing the comprehensive optimization of aerodynamic and acoustic performance.

[0014] Further, the cross-sectional shape of the guide vane is a symmetrical airfoil. The symmetrical airfoil can effectively maintain airflow adhesion and suppress boundary layer separation due to the geometric property that the chord line coincides with the arc line.

[0015] The impeller assembly provided by the present application comprises a plurality of fan blades, wherein the fan blades are symmetrically arranged around a central rotating shaft; the impeller assembly further comprises a generator assembly and a support structure; and the support structure is used for supporting the impeller assembly and the generator assembly. The structure forms a complete vertical axis wind turbine device.

[0016] In order to further improve the noise reduction effect, the guide vanes of the annular fairing are made of foam aluminum profile stretch forming. The foam aluminum profile is a porous lightweight structure, so that a turbulence sound absorbing layer is formed on the outer surface of the annular fairing, and the porous characteristics of the foam aluminum profile are used to absorb vortex noise.

[0017] Further, the ring-shaped fairing is connected with the support structure through a detachable support. This structure enables the ring-shaped fairing to be applied to different types of vertical axis wind turbines.

[0018] Further, the included angle between the windward edge and the vertical direction is 10°.

[0019] Further, the tangential angle between the connecting line of the windward edge and the guide edge and the outer peripheral surface of the ring-shaped fairing is 40°.

[0020] Further, the included angle between the windward edge and the guide edge of two adjacent guide vanes is 15°.

[0021] Compared with the prior art, the present application has the following remarkable advantages:

[0022] 1. The ring-shaped fairing forms a convergent wind channel, increases the wind speed entering the impeller, and improves the wind energy utilization rate;

[0023] 2. The ring-shaped fairing cooperates with the foam aluminum profile to absorb the medium-high frequency noise generated by the rotating airflow and guide the noise upward, thereby reducing the overall noise;

[0024] 3. The guide vanes of the ring-shaped fairing are made of foam aluminum profiles through a stretching process, and have the advantages of light weight and high strength, and are suitable for urban ecological wind power generation systems such as roofs and parks;

[0025] 4. The ring-shaped fairing adopts a detachable structure, which is convenient for later maintenance and replacement. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram of a noise source of a vertical axis wind turbine;

[0027] Figure 2 It is a perspective view of the noise reduction device of the vertical axis wind turbine according to the embodiment of the present application;

[0028] Figure 3 It is a schematic diagram of the included angle A of the noise reduction device of the vertical axis wind turbine according to the embodiment of the present application;

[0029] Figure 4 It is a schematic diagram of the tangential angle β of the noise reduction device of the vertical axis wind turbine according to the embodiment of the present application;

[0030] Figure 5 It is a schematic diagram of the airflow guide of the noise reduction device of the vertical axis wind turbine according to the embodiment of the present application Figure 1 ;

[0031] Figure 6 It is a schematic diagram of the airflow guide of the noise reduction device of the vertical axis wind turbine according to the embodiment of the present application Figure 2 ;

[0032] Figure 7The figure is a projection surface schematic view of the guide vane of the noise reduction device of the vertical axis wind turbine of the embodiment of the present application.

[0033] Figure 8 The figure is an angle C schematic view of the noise reduction device of the vertical axis wind turbine of the embodiment of the present application.

[0034] In the figure: 10, annular fairing; 11, guide vane; 111, windward edge; 112, wind guide edge; 12, first projection surface; 13, second projection surface; 20, impeller assembly. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0036] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom end" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "provided with", "sleeved / connected", "connected" and the like should be broadly understood, for example, "connected" can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] The existing vertical axis wind turbine has the following technical problems: the blades produce strong disturbance with the airflow during rotation, especially in urban, roof, community and other distributed scenarios, the aerodynamic noise and mechanical noise are obvious, in addition, the generator also produces mechanical noise during operation, such as Figure 1As shown, 1 is a blade and airflow friction noise source, 2 is a motor mechanical noise source; the existing structure is mostly bare impeller, without effective airflow rectification and noise reduction measures; when the airflow enters the impeller area, part of the wind energy is not fully captured, causing energy loss, and there is also the problem of low wind energy utilization rate.

[0039] Based on the above technical problems, the embodiment of the present application provides a vertical axis wind turbine noise reduction device, which integrates fan blades, motors, support frames and other core components, and the most prominent feature is the use of a noise reduction type fairing, which is optimized in terms of material, structure and fluid dynamics, aiming to significantly reduce the noise of the fan in operation. Figure 2 As shown, specifically includes an impeller assembly 20 and a ring-shaped fairing 10 coaxially covering the impeller assembly 20.

[0040] Among them, the ring-shaped fairing 10 is formed by a plurality of guide vanes 11 and has a semi-closed ring structure that is wide at the top and narrow at the bottom. The guide vanes 11 are evenly arranged along the circumferential direction of the ring-shaped fairing 10, and the embodiment of the present application adopts a unique arrangement density and arrangement angle. As shown, Figures 2 to 3 As shown, two fixing rings are respectively arranged at the upper and lower end faces of the ring-shaped fairing 10 for fixing the guide vanes 11.

[0041] As shown, Figures 5 to 6 The technical scheme provided by the embodiment of the present application is to form a rotational flow inside the ring-shaped fairing 10, compress it, then push it to the center, and finally suck it upwards, so that a naturally formed rotational flow diffuser exists inside the ring-shaped fairing 10, a stable spiral rising air column is constructed inside the cover, and then the noise generated inside the ring-shaped fairing 10 is guided to the sky, achieving the effect of reducing noise.

[0042] Specifically, the windward side 111 of the guide vane 11 is outward along the radial direction of the ring-shaped fairing 10, and the windward side 112 is inward along the radial direction of the ring-shaped fairing 10. As shown, Figure 3 As shown, the included angle A between the windward side 111 and the vertical direction is 6°~12°; as shown, Figure 4 As shown, the tangent angle β between the connecting line of the windward side 111 and the windward side 112 and the outer circumferential surface of the ring-shaped fairing 10 is 25°~55°.

[0043] Firstly, the included angle A between the windward side 111 and the vertical direction is 6°~12°, that is, the outer side of the ring-shaped fairing 10 is inclined at an angle of 6°~12°. This angle not only determines the contraction ratio of the internal passage of the ring-shaped fairing 10, but also determines whether the airflow will separate. It is selected by taking into account sufficient contraction ratio and avoiding flow separation, so that the flow passage remains continuous and smooth, and the airflow can be accelerated stably without dispersion.

[0044] When horizontal airflow impacts the annular fairing 10, the airflow impacts the side surface of the fairing 10. The inclined surface creates axial and tangential coupling with the fluid. Combined with the tangential arrangement of the guide vanes 11, the airflow, upon entering the annular fairing 10, is guided at the fairing wall to flow with both axial and tangential components, generating a continuous axial component, i.e., curl. The tangential force then imparts angular momentum to the airflow. Under the influence of angular momentum, the airflow rotates around the axis and generates a low-pressure gradient axially. This low-pressure gradient is caused by a radial pressure gradient due to centrifugal force, with lower pressure in the central region. This low pressure pulls the axial upward component, forming an upward swirling flow. The aerodynamic mechanism is as follows:

[0045] With the top diameter of the annular fairing 10 Bottom diameter For example, .

[0046] Regarding the formation of the gently constricting flow channel in the annular fairing 10:

[0047] The geometric contraction ratio of the annular fairing 10 is as follows: According to the fluid continuity equation The calculation yielded: Considering friction and diffusion losses, the actual improvement is: That is, the effective wind speed is increased by 10% to 30%.

[0048] In engineering aerodynamics, if the angle of airflow in a contracting channel is too large, boundary layer separation will occur, resulting in increased pressure loss and energy loss. The optimal cone angle for a gently contracting channel is 6° to 12°. Within the annular fairing at this cone angle, there is a low-drag contraction zone while maintaining boundary layer adhesion. 10° is the optimal angle, ensuring that the airflow remains attached throughout the entire channel without vortex shedding, thereby achieving high-efficiency acceleration.

[0049] Regarding the upward lifting of axial velocity guided by the annular fairing 10:

[0050] The inclination angle of the annular fairing 10 decomposes the external airflow velocity V into: , ,in It is the axial velocity. This is the inward convergence velocity; the velocities corresponding to 10° are: (Maintain axial velocity) (This creates an inward convergence trend). It is evident that the airflow is decomposed under the action of the annular fairing 10. The inward velocity component ensures that the swirling flow maintains centripetal convergence and upward merging streamlines within the fairing, which is beneficial for forming a stable spiral air column. This prevents the airflow from being thrown outwards out of the fairing, thus preventing the swirling flow from expanding outwards; the airflow is compressed towards the central region and pulled upwards; providing a stable and predictable geometric channel for the swirling flow, promoting the formation of a stable path for the swirling flow.

[0051] In terms of the suction effect generated after the vortex is established:

[0052] When the guide vane 11 establishes the tangential velocity After that, the flow field appears a centrifugal pressure distribution: ; the pressure increases along the radial direction, and a low pressure core is formed at the center. At this time, the 10° conical geometry of the cover body will further draw the external gas into the cover, thereby forming a three-section continuous flow path of suction-acceleration-ascending. This structure is equivalent to an air ejector, which enhances the pressure difference above the wind wheel and improves the flow through the impeller.

[0053] If the conical angle is too large, the vortex will separate from the wall, and the suction capacity will decrease; if the conical angle is too small, the contraction is insufficient, and the wind speed improvement is not obvious. Therefore, in the embodiment of the present application, the optimal conical angle of the slow contraction flow passage is 6°-12°, and 10° is the optimal angle, so that the boundary layer separation is avoided and the contraction efficiency is ensured in the whole passage.

[0054] Secondly, the guide vane 11 has a tangential angle β of 25°-55°, and the tangential angle β of 40° is preferably adopted, which will generate a continuous guiding force on the airflow, forcing it to increase a tangential velocity component on the basis of the axial flow. Under the joint action of all guide vanes 11, a spiral upward rotating flow around the center axis of the fan is finally formed in the annular fairing 10, which can effectively comb the airflow, reduce the noise sources such as vortex shedding, and guide the sound wave energy to high altitude, thereby realizing the noise reduction effect. The aerodynamic mechanism is as follows:

[0055] Taking the tangential angle β of 40° as an example:

[0056] The maximum controllable vortex momentum is obtained by velocity decomposition, and the incoming flow velocity V is decomposed into: , , and , to obtain , which provides a strong tangential momentum; , which maintains stable axial penetration.

[0057] It can be seen that when the tangential angle β is 40°, the tangential velocity is large enough to generate effective vortex; it will not be too large to make the vortex "diffuse or detach"; at the same time, sufficient axial flow is maintained to make the vortex advance upward.

[0058] If the tangential angle β is greater than 55°, the vortex will be too strong to form a backflow area; if the tangential angle β is less than 25°, the vortex will be insufficient to form a low pressure core. Therefore, the tangential angle β is 25°-55°, and 40° is preferably adopted, which belongs to a strong vortex but a controllable interval.

[0059] When the tangential angle β is 40°, the vorticity number S can be obtained, and the vorticity number , and the velocity decomposition of 40° is substituted: .

[0060] In the engineering, the range of vorticity and phenomenon are distinguished as follows: if the vorticity S is less than 0.4, the vortex is weak and cannot form a low pressure core; if 0.4<=S<=0.8, it is a stable ideal vortex range; if S is greater than 0.8, the vortex is too strong, and backflow and energy loss occur.

[0061] Therefore, the tangential angle β is 40°, so that the vortex flow established by the guide vane 11 is the most stable and effective vortex flow structure, which can form a vortex and a slow contraction flow channel, and realize the stable spiral air column.

[0062] The tangential angle β of the guide vane 11 is 40°, the tangential velocity generated in the annular fairing 10 is superimposed with the acceleration of the contraction air duct, finally forms a vortex and is compressed, and then is pushed to the center, and finally is sucked upward, so that there is a naturally formed vortex diffuser in the annular fairing 10, which structures a stable spiral rising air column in the fairing, and continuously provides the impeller with airflow with higher energy density and better uniformity.

[0063] In summary, the technical scheme provided by the embodiment of the present application first adopts the annular fairing 10 with an included angle A between the windward edge 111 and the vertical direction of 6°-12°, forms a slow contraction flow channel in the annular fairing 10, realizes stable acceleration, guides the axial velocity to go up, and promotes the vortex to form a stable path; after the vortex is established, a centrifugal low pressure core is generated to amplify the suction effect; secondly, the tangential angle β between the connecting line of the windward edge 111 and the guide edge 112 and the outer peripheral surface of the annular fairing 10 is 25°-55°, the wind speed is decomposed to obtain the maximum controllable vortex momentum, and the vortex is in the best stable zone, the vortex and the slow contraction flow channel are combined to form an upward spiral air column, the noise generated in the annular fairing 10 is guided upward, and the effect of reducing noise is achieved.

[0064] As shown in Figure 7 In order to further improve the noise reduction effect, the projection surface formed by the projection line between the two adjacent guide vanes 11 and the axis of the annular fairing 10 is respectively a first projection surface 12 and a second projection surface 13, and there is an overlapping surface between the first projection surface 12 and the second projection surface 13. The above structure limits the setting density of the guide vane 11, and by designing the density of the rotational arrangement of the guide vane 11, there is no noise leakage gap between the axis of the annular fairing 10 and the outside, the noise generated in the annular fairing 10 can be reflected and shielded, the noise can be collected and guided out of the upper end opening of the annular fairing 10, and the noise reduction capacity is significantly improved, which is equivalent to upgrading the annular fairing 10 from a passive airflow channel to an active aerodynamic acoustic integrated innovative green energy device.

[0065] Further, the guide vane 11 of the annular fairing 10 is made by stretching and forming a foam aluminum profile. The foam aluminum profile is a porous lightweight structure, filled with a large number of bubbles inside, the minimum pore size can reach 0.3mm, the porosity can reach more than 90%, similar to a honeycomb, with excellent sound insulation and sound absorption capacity, capable of absorbing mid-high frequency noise greater than 500Hz, effectively reducing the propagation of noise of different frequencies, forming a turbulence sound absorption layer on the outer surface of the annular fairing, and absorbing vortex noise by the porous characteristics of the foam aluminum profile.

[0066] On this basis, the impeller assembly 20 of the embodiment of the application comprises a plurality of fan blades, the fan blades are symmetrically arranged around the central rotating shaft, the number of the fan blades is usually 2-6, and the material can be aluminum alloy, composite material or steel structure. The embodiment of the application also comprises a generator assembly and a support structure, the support structure is used for supporting the impeller assembly and the generator assembly, and the structure forms a complete vertical axis wind turbine device.

[0067] The design of the annular fairing of the embodiment of the application also brings greater efficiency improvement to the wind energy utilization of the impeller assembly 20.

[0068] Firstly, the wind speed brings the improvement of power:

[0069] Based on the wind energy formula: The annular fairing 10 with the cone angle improves the wind speed to .

[0070] The influence of the wind speed improvement on the generator power Therefore, if the wind speed is improved by 20%, the influence of the generator power is , that is, the power is improved by 73%.

[0071] Secondly, the rotation flow brings the improvement of power:

[0072] The rotation flow can make the flow field more uniform, and the rotation flow improves the uniformity of the incoming wind, so that is improved from 0.22 to 0.28, that is, the power is improved by 27%.

[0073] Therefore, the overall power is improved: 1.73*1.27=2.2, that is, the power is improved by 120%.

[0074] For example Figure 8As shown, in order to further improve the wind energy utilization, the angle C between the windward edge 111 and the connecting line of the wind guide edge 112 of the two adjacent guide vanes 11 is 10°-20°, preferably 15°. The guide vanes 11 are arranged at the angle to form a tapered flow passage. Based on the law of conservation of mass and Bernoulli's principle, the airflow forms an orderly accelerated flow, and the guide vanes 11 work together to convert the axial airflow into a spiral flow rising around the shaft. Not only can the vortex noise be reduced by combing the main flow, but also the sound wave propagation path can be changed by the airflow guide, and the aerodynamic and acoustic performance is comprehensively optimized.

[0075] Further, the cross-sectional shape of the guide vane 11 is a symmetrical airfoil. The guide vane 11 with the arc-shaped camber surface can accelerate the airflow entering the impeller area, increase the local wind speed, and increase the inlet area of the fairing. In addition, the geometric property that the arc line coincides with the chord line can effectively maintain airflow adhesion and suppress boundary layer separation.

[0076] In summary, the guide vane 11 adopts a symmetrical airfoil cross section and is arranged at an angle C of 15° to form a tapered flow passage. Based on the law of conservation of mass and Bernoulli's principle, when the horizontal airflow enters the tapered flow passage, the flow area decreases, resulting in an increase in flow velocity and a decrease in static pressure, forming an orderly accelerated flow. The guide vanes work together to convert the axial airflow into a spiral flow rising around the shaft. This flow field not only reduces vortex noise by combing the main flow, but also changes the sound wave propagation path by the airflow guide, and comprehensively optimizes the aerodynamic and acoustic performance.

[0077] Further, the annular fairing 10 is connected to the support structure through a detachable support. This structure allows the annular fairing 10 to be detached according to the use requirements, facilitating maintenance and transportation, and can be applied to different types of vertical axis wind turbines.

[0078] In combination with the above structural features provided in the embodiments of the present application, the noise reduction amplitude is significantly improved. First, the structure noise reduction is achieved through the sound-absorbing material and the physical shielding of the annular fairing. The foam aluminum profile absorbs medium and high frequencies, and the cover wall of the annular fairing blocks the noise of the rotating fan blades. Second, the rotational flow generated in the annular fairing can improve the angle of attack stability, and the rotational flow changes the wind angle of the fan blades, so that the fan blades do not experience periodic stall and strip separation vortex. Finally, the upward rotational flow discharges the noise energy upward, which directionally weakens the noise.

[0079] The following is an embodiment of a simulation experiment on the traditional vertical wind turbine and the technical solution provided in the present application:

[0080] The angle between the windward edge of the fin of the circular fairing adopted in embodiments 1 to 4 and the vertical direction is 10°, the tangential angle between the connecting line of the windward edge and the guide edge and the outer peripheral surface of the circular fairing is 40°, and the angle between the windward edges of two adjacent fins and the connecting line of the guide edges is 15°.

[0081] Specifically, the decibel value experimental data of 10m near field and 30m far field in embodiments 1 and 2 respectively, three wind speed values of 6m / s, 8m / s and 10m / s are used for simulation experiment.

[0082] Embodiments 3 and 4 are respectively The fan power experimental data of pressure coefficients of 0.22 and 0.28, three wind speed values of 6m / s, 8m / s and 10m / s, and three wind speed correction coefficients of 1.1, 1.15 and 1.2 are used for simulation experiment.

[0083] The specific implementation is as follows:

[0084] Embodiment 1

[0085] Table 1: Comparison table of fan experimental simulation noise at 10m near field

[0086]

[0087] Embodiment 2

[0088] Table 2: Comparison table of fan experimental simulation noise at 30m far field

[0089]

[0090] Embodiment 3

[0091] Table 3: Comparison table of fan experimental simulation power with pressure coefficient of 0.22

[0092] Embodiment 4

[0093] Table 4: Comparison table of fan experimental simulation power with pressure coefficient of 0.28

[0094]

[0095] From embodiments 1 to 4, it can be known that:

[0096] I. In terms of noise:

[0097] I. In terms of noise:

[0098] ​In the case of wind speed 8 m / s, the traditional fan 82 dB at 10 m near field, the application 64 dB, down 18 dB, the process of high frequency is the main decline interval; 30 m far field under the same conditions, down 14 dB.

[0099] In the case of low wind speed 6 m / s and high wind speed 10 m / s, the noise reduction level at 10 m near field is 15 dB to 20 dB.

[0100] II. In terms of fan power:

[0101] In the case of wind speed correction coefficient 1.2, the annular fairing leads to an effective wind speed increase of 20% and a pressure coefficient up to 0.28.

[0102] In the case of low wind speed 6 m / s, the traditional fan output is 4.481 kW, and the application output is 9.854 kW, with a speed gain and double increase of 119.9%.

[0103] If only the speed is considered, i.e. the wind speed correction coefficient is kept at 1.15, and the pressure coefficient is kept at 0.22, then in the case of medium wind speed 8 m / s, the output is 16.15 kW, which is 52% higher than the traditional fan.

[0104] If more conservative or more realistic values are used, for example =1.10 or only up to 0.24, there will still be a significant power gain, an increase of 20% to 60%, depending on the specific parameter adjustment.

[0105] In summary, the annular fairing with a cone angle of 10°, a guide vane tangential angle of 40°, and a guide vane included angle of 10°, combined with sound-absorbing material, has strong absorption and shielding effect on medium and high frequency noise, and the near field noise is expected to be reduced by 15-20 dB(A). At the same time, the effective wind speed increase of 10%-20% caused by the fairing and the rotational flow generated by the guide vane coupling, according to the power and wind speed three times relationship, the unit output power can be increased by about +120% under common working conditions, see the table =1.2, from 0.22 to 0.28, an estimated increase of about +119.9% is obtained at 6 m / s.

[0106] The design parameters of this patent scheme are in the best interval of aerodynamic performance, which can not only achieve significant power increase through moderate rotational flow and wind tunnel acceleration, but also effectively suppress flow separation and vortex shedding, thereby ensuring excellent noise reduction effect.

[0107] The annular fairing used in Examples 5 to 8 has an angle of 6° between the windward side of the guide vane and the vertical direction, a tangential angle of 25° between the line connecting the windward side and the guide vane and the outer circumferential surface of the annular fairing, and an angle of 10° between the line connecting the windward side and the guide vane of two adjacent guide vanes.

[0108] Specifically, Examples 5 and 6 are experimental data of decibel values ​​at a near field of 10m and a far field of 30m, respectively, and simulation experiments are conducted using three wind speed values ​​of 6m / s, 8m / s, and 10m / s, respectively.

[0109] Examples 7 and 8 are respectively Experimental data on fan power with pressure coefficients of 0.22 and 0.23 were used to conduct simulation experiments with three wind speed values ​​of 6 m / s, 8 m / s, and 10 m / s, and three wind speed correction coefficients of 1.05, 1.10, and 1.12.

[0110] The specific implementation method is as follows:

[0111] Example 5

[0112] Table 5: Comparison of Experimental Simulation Noise Levels for Fans at a Near-Field Location of 10m

[0113]

[0114] Example 6

[0115] Table 6: Comparison of Experimental Simulation Noise Levels for Wind Turbines at a Far Field of 30m

[0116]

[0117] Example 7

[0118] Table 7: Pressure Coefficient Comparison table of simulated power for wind turbines with a power rating of 0.22

[0119]

[0120] Example 8

[0121] Table 8: Pressure Coefficient Comparison table of simulated power for wind turbines with a power rating of 0.23

[0122]

[0123] As can be seen from Examples 5 to 8:

[0124] I. Regarding noise:

[0125] In the case of high wind speed 10 m / s, the traditional fan is 86 dB at 10 m near field, and the application scheme is 62 dB, a decrease of 24 dB. In this process, the airflow disturbance intensity and vortex shedding noise are significantly weakened due to the reduction of the guide vane angle.

[0126] Under the same working condition, it decreases by 17 dB at 30 m far field. The noise reduction at 10 m / s wind speed is further increased, highlighting the optimization effect of the aerodynamic noise source.

[0127] II. In terms of fan power:

[0128] The wind speed correction coefficient is 1.12, and the annular fairing causes the effective wind speed to increase by 12% and the pressure coefficient to increase slightly to 0.23 due to weak swirl.

[0129] At medium wind speed 8 m / s, the traditional fan outputs 10.62 kW, and the application scheme outputs 15.619 kW, with a speed gain and power increase of 43.1% in the combined case of double increase.

[0130] If only the speed gain is considered, the wind speed correction coefficient is kept at 1.10, and the pressure coefficient is kept at 0.22, then at low wind speed 6 m / s, the output is 5.96 kW, which is 33.1% higher than the traditional fan. This reflects the conservative gain level brought by the contraction effect of the annular fairing when the swirl efficiency is weak.

[0131] Parameter sensitivity analysis shows that the power increase is more sensitive to the wind speed correction coefficient , and the pressure coefficient has limited increase. The key path to achieve higher gain is to optimize the annular fairing aerodynamic design to increase the value.

[0132] In summary, the annular fairing with a cone angle of 10°, a guide vane tangential angle of 40°, and a guide vane included angle of 10° has the following characteristics: it sacrifices part of the power increase potential to achieve better low-noise performance. The power increase is conservative, with a moderate level of about 40%, compared to the aggressive gain of about 120% of the original scheme. The noise reduction effect is more outstanding. Through the above power reduction adjustment of aerodynamic parameters, double control of noise source and propagation path is achieved, which is especially suitable for low-turbulence urban wind field environment with strict low-noise requirements. The near-field noise is expected to decrease by up to ~24 dB.

[0133] The angle between the windward edge of the fin of the circular fairing adopted in embodiments 9 to 12 and the vertical direction is 12°, the tangential angle between the connecting line of the windward edge and the guide edge and the outer peripheral surface of the circular fairing is 55°, and the angle between the windward edges of two adjacent fins and the connecting line of the guide edges is 20°.

[0134] Specifically, the decibel value experimental data of 10 m near field and 30 m far field in embodiments 9 and 10 are respectively simulated by using three wind speed values of 6 m / s, 8 m / s and 10 m / s.

[0135] Embodiments 11 and 12 are respectively The fan power experimental data of pressure coefficients of 0.22 and 0.23 are respectively simulated by using three wind speed values of 6 m / s, 8 m / s and 10 m / s, and three wind speed correction coefficients of 1.05, 1.10 and 1.12.

[0136] The specific implementation is as follows:

[0137] Embodiment 9

[0138] Table 9: Comparison table of fan experimental simulation noise at 10 m near field

[0139]

[0140] Embodiment 10

[0141] Table 10: Comparison table of fan experimental simulation noise at 30 m far field

[0142]

[0143] Embodiment 11

[0144] Table 11: Comparison table of fan experimental simulation power of pressure coefficient 0.23

[0145]

[0146] Embodiment 12

[0147] Table 12: Comparison table of fan experimental simulation power of pressure coefficient 0.25

[0148]

[0149] From embodiments 9 to 12, it can be seen that:

[0150] I. In terms of noise:

[0151] Under a medium wind speed of 8 m / s, the noise reduction of a conventional wind turbine at a near-field distance of 10 m is 82 dB, while that of the proposed solution is 67 dB, a reduction of 15 dB. Compared with embodiments 1-8, the overall noise reduction is narrowed, decreasing by 9 dB to 16 dB.

[0152] II. Regarding fan power:

[0153] In applications requiring high power output, i.e., with a wind speed correction factor... The pressure coefficient is 1.24. It is 0.25.

[0154] At a medium wind speed of 8 m / s, a conventional wind turbine outputs 10.62 kW, while the solution proposed in this patent application outputs 24.01 kW. This represents a significant improvement in speed gain compared to... In the case of the dual enhancement, the power is increased by 126.1%, which reflects the ultimate improvement of the overall power brought about by the high vortex and strong suction design, which is in the range of 101% to 135%.

[0155] Parameter sensitivity analysis shows that power increase affects the wind speed correction factor kv and the pressure coefficient. Both are highly sensitive. Under conservative parameters, that is, at... =1.15, At a value of 0.23, the power increase is approximately 65.9%; under aggressive parameters, i.e. =1.32, At a power efficiency of 0.27, the power output is increased by more than 190%, demonstrating the enormous potential for power performance improvement under this parameter mode.

[0156] In summary, the annular fairing with a cone angle of 12°, a guide vane tangential angle of 55°, and a guide vane included angle of 20° is a design scheme that pursues extreme power performance. It achieves a significant power increase by enhancing the contraction effect of the fairing and the swirl generation capability of the guide vanes, achieving more than double the power increase over a wide wind speed range. The performance improvement is far greater than other schemes. However, the noise reduction performance is weakened, and aerodynamic disturbances inevitably lead to increased source noise, resulting in a reduced overall noise reduction effect. Near-field noise is reduced by 9dB~16dB.

[0157] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A vertical axis wind turbine noise reduction device, characterized by: The impeller assembly comprises a plurality of blades, and a ring-shaped fairing coaxially covering the impeller assembly. The ring-shaped fairing is formed by a plurality of guide vanes in a semi-enclosed ring shape with a width increasing from top to bottom. The guide vanes are uniformly arranged along the circumferential direction of the ring-shaped fairing. The angle between the windward side and the vertical direction is 6°-12°. The tangential angle between the connecting line of the windward side and the guide wind side and the outer circumferential surface of the ring-shaped fairing is 25°-55°. The projection lines between two adjacent guide vanes and the axis of the ring-shaped fairing form a first projection surface and a second projection surface, respectively.

2. The vertical axis wind turbine noise reduction apparatus of claim 1, wherein: The cross-sectional shape of the guide vanes is a symmetric airfoil shape.

3. The vertical axis wind turbine noise reduction apparatus of claim 1, wherein: The angle between the connecting lines of the windward side and the guide wind side of two adjacent guide vanes is 10°-20°.

4. The vertical axis wind mill noise reduction device as claimed in claim 1, wherein: The impeller assembly comprises a plurality of blades, and a ring-shaped fairing coaxially covering the impeller assembly.

5. The vertical axis wind turbine noise reduction apparatus of claim 3, wherein: The guide vanes of the ring-shaped fairing are made of foam aluminum profile stretch forming.

6. A vertical axis wind turbine noise reduction device according to any one of claims 1 to 5, characterised in that: The ring-shaped fairing is connected to the support structure by a detachable support.

7. A vertical axis wind turbine noise reduction device according to any one of claims 1 to 5, characterised in that: The angle between the windward side and the vertical direction is 10°.

8. The vertical axis wind mill noise reduction device as claimed in claim 1, wherein: The tangential angle between the connecting line of the windward side and the guide wind side and the outer circumferential surface of the ring-shaped fairing is 40°. The angle between the connecting lines of the windward side and the guide wind side of two adjacent guide vanes is 15°.

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