Wind wheel for fan, blades of wind wheel and centrifugal fan

Abstract

The invention discloses a wind wheel for a fan, blades of the wind wheel and a centrifugal fan, the blades of the wind wheel for the fan are equal-thickness blades, and blade molded lines of the blades are obtained through six-time curve function fitting. The blades are uniform-thickness blades, and the blade profiles are obtained through six-degree curve function fitting, so that airflow noise caused by the fact that traditional blades are composed of polylines is avoided; and the problem that airflow cannot smoothly flow due to a single-arc blade can be avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of centrifugal fan, in particular to a fan wheel, a blade thereof and a centrifugal fan. BACKGROUND

[0002] At present, the efficiency of centrifugal fan is generally low. The main reason for the low efficiency of centrifugal fan is the low efficiency of the core component of centrifugal fan, i.e. the fan wheel (impeller). The main reason for the low efficiency of fan wheel is that the blade design of fan wheel does not match the airflow flow pattern, thus causing various adverse flow phenomena, resulting in low efficiency, high noise and low air volume. SUMMARY

[0003] In order to solve at least one of the foregoing problems, according to one aspect of the present application, a blade of a fan wheel is provided.

[0004] The blade of the fan wheel is an equal-thickness blade, and the blade profile of the blade is obtained by fitting a six-order curve function. Since the blade is an equal-thickness blade and the blade profile is obtained by fitting a six-order curve function, the airflow noise caused by the traditional blade composed of multiple line segments is avoided. Moreover, the problem that airflow cannot flow smoothly caused by single circular-arc blade is avoided.

[0005] In some embodiments, the six-order curve function is y = -0.0002x 6 + 0.0059x 5 - 0.0867x 4 + 0.6146x 3 - 2.2099x 2+3.4842x+10.92. On the one hand, using a six-order curve function to fit the profile of the blade can give the blade a very high degree of design freedom and enable the profile to be precisely controlled: compared with low-order curves (such as quadratic or cubic curves, which have limited geometric characteristics), a high-order six-order curve can not only control the curvature and the rate of change of the curvature (which is crucial for pressure distribution) but also independently adjust the geometric characteristics of different regions (for example, the blade leading edge radius can be independently optimized to improve high-angle-of-attack performance while the trailing edge angle is maintained to control airflow separation), and can precisely fit a target blade profile; on the other hand, using a six-order curve function to fit the profile of the blade can give the blade excellent aerodynamic performance: a six-order curve can generate a very smooth blade surface, avoiding the tiny discontinuities that low-order curves can bring, thereby ensuring smooth airflow transition and reducing frictional resistance and form drag; on the other hand, a six-order curve can very precisely describe the arrangement path and thickness distribution of the spar cap inside the blade, which allows the designer to thin the thickness of other regions as much as possible while ensuring sufficient structural strength in key regions (such as the blade root); moreover, the super-high smoothness provided by a high-order curve means a more gradual geometric transition, which helps to reduce stress concentration and improve the fatigue life of the blade; moreover, parameterizing the traditional double-arc or single-arc blade profile makes the blade profile more controllable during design, and the value range of x can be adjusted according to the requirements of the fan for air volume and noise to obtain a blade profile that meets the requirements.

[0006] In some embodiments, the tail of the blade is provided with a bevel structure. The inventors have found in the development process that one of the main sources of noise of a fan is the "blade tip vortex" and turbulence generated when the blade tip moves at high speed through the air; when the blade is straight (without beveling), the generation and shedding of the blade tip vortex is very violent and concentrated, producing high-intensity, low-frequency noise; moreover, when the blade rotates, it encounters gusts or wind speed shear (different wind speeds at different heights), and the entire blade will instantaneously bear uneven loads, which is a great test for the blade root and main bearing. After the bevel structure is provided at the position of the blade, the concept of the formation process of the blade tip vortex is changed, and the bevel structure disperses a concentrated and powerful vortex into multiple smaller and weaker vortices; at the same time, the beveling causes the positions where the blade edge meets the incoming flow to be staggered in time, reducing the pulsed pressure pulsation, thereby significantly reducing noise; in addition, the bevel structure also functions as a "load softening" structure; when a strong wind hits the blade, the beveling part does not simultaneously transmit the load to the root, but has a slight delay and dispersion effect; this reduces the peak value of the dynamic load and smooths the torque output, thereby reducing the fatigue load and ultimate load borne by the blade root, hub and transmission chain, making it possible to design a lighter blade and support structure, or prolong the service life of the entire fan.

[0007] In some embodiments, the angle of the chamfered structure is 45°±5°. The inventors have found in the course of their research that the angle of the chamfering does not have a linear effect on noise reduction. As the angle is increased from 0°, the noise reduction effect is very obvious. However, when the angle is increased to a certain extent (e.g. 45°-50°), the increase in noise reduction benefit is no longer significant. Moreover, an excessively large chamfering angle (e.g. more than 60°) can have a negative impact, such as reducing the effective swept area of the blade, introducing unnecessary induced drag, reducing wind energy capture efficiency, and causing significant bending-torsion coupling effects, which can lead to unpredictable vibration problems and higher structural strength requirements.

[0008] In some embodiments, x∈[0, 17.38].

[0009] According to another aspect of the present application, a wind wheel for a fan is provided, which comprises the blade of the wind wheel for a fan described above. Since the blade of the wind wheel is an equal-thickness blade and the blade profile is fitted by a six-degree curve function, the airflow noise caused by the traditional blade composed of multiple line segments is avoided, and the problem of airflow not flowing smoothly caused by a single circular-arc blade is also avoided.

[0010] In some embodiments, the wind wheel for a fan further comprises a hub, a spoke, and a circular ring, and the blade, the hub, the spoke, and the circular ring are integrally formed. In this way, not only can stress concentration and fatigue crack sources caused by welding or bolt connection be avoided, but also the problem of increased fluid resistance caused by welds and bolts can be avoided, and the structure can be simplified to the greatest extent.

[0011] In some preferred embodiments, the diameter of the circular ring is slightly larger than the outer diameter of the blade. In general, a small gap exists between the tip of the blade (blade tip) and the stationary volute of a wind wheel. Due to the pressure difference between the working area (high-pressure area) of the impeller and the inlet area (low-pressure area), high-pressure gas will leak back to the low-pressure area through the gap, forming a so-called "tip leakage vortex". This leakage vortex does not participate in effective work, directly causing energy loss and reducing the efficiency of the fan. At the same time, the tip leakage vortex and the flow separation at the leading edge of the blade are two main sources of aerodynamic noise, which can produce high-frequency "squeaking" sound and broadband noise. Moreover, at the leading edge (inlet) of the blade, if the incoming flow conditions are poor (e.g. improper attack angle), flow separation can easily occur, resulting in instability.

[0012] The embodiment sets a ring on the blade, and sets the diameter of the ring to be slightly larger than the outer diameter of the blade, which is equivalent to setting a physical barrier in the "upstream" of the tip clearance. It forces the leakage flow to take a longer and more tortuous path to leak back, greatly increasing the flow resistance of the leakage flow, thereby improving the volumetric efficiency and overall aerodynamic efficiency of the fan, while suppressing the tip leakage and flow separation, and weakening the generation mechanism of the above-mentioned noise from the source; the embodiment plays a "guiding" and "restricting" role on the airflow entering the blade passage through the slightly larger ring, which can guide the airflow to enter the tip region more smoothly, and delay or eliminate the flow separation at the leading edge of the blade through the restriction of the near-wall flow field; in addition, the extended ring plays a role of "reinforcing ring" in structure, which connects the tip parts of all blades together to form a closed ring structure, which significantly improves the overall structural stiffness and deformation resistance of the impeller.

[0013] In some embodiments, the number of blades is odd. Thus, the resonance problem caused by the even number of blades can be avoided, and the aerodynamic noise is reduced.

[0014] In some embodiments, the hub is a conical frustum. For example, the diameter of the hub gradually decreases from the inlet side of the impeller to the middle side of the impeller. Since the conical frustum can provide a smooth and gradual guide surface, the airflow can flow along the inclined surface of the cone and gradually transition from axial flow to radial flow of the impeller, which significantly reduces the impact and separation loss at the inlet, so that the airflow can enter the flow passage between the blades more "obediently"; moreover, the conical frustum structure can better match the absolute velocity distribution of the inlet and the peripheral velocity distribution of the impeller, thereby reducing the attack angle between the inlet airflow and the blade, achieving "non-impact inlet" or close to non-impact inlet, which directly improves the efficiency of the fan; at the same time, the conical frustum structure as a transition form has a more smooth shape change, which can more uniformly transmit the centrifugal force and aerodynamic force transmitted by the blade to the main shaft and the bearing, reduce stress concentration, and improve the fatigue life of the structure.

[0015] According to another aspect of the present application, a centrifugal fan is provided, which comprises the blade of the fan wheel as described above; or comprises the fan wheel as described above. Since the blade of the fan wheel is an equal-thickness blade, and the blade profile is obtained by fitting a six-order curve function, the airflow noise caused by the traditional blade composed of multiple line segments is avoided; and the problem that the airflow cannot flow smoothly caused by the single-arc blade is also avoided.

[0016] In some embodiments, the centrifugal fan further comprises a volute, and a bending structure is arranged at the air outlet of the volute, and the bending direction is inward.

[0017] Because the gas flows through a long path and its cross-sectional shape changes constantly within the volute, the gas viscosity causes viscous friction between the airflow and the inner wall of the volute, resulting in an irregular turbulent boundary layer on the inner wall of the volute. At the same time, if the curvature transition of the volute spiral design is unreasonable, it will cause local stagnation and eddy currents in the airflow within the volute, resulting in additional energy dissipation of the airflow.

[0018] This embodiment, by bending the volute outlet inward, redirects the originally outward-flowing airflow inward, making it more axial. During this forced redirection, the tangential velocity component of the airflow is reduced, and its corresponding kinetic energy is recovered and converted into additional static pressure. By recovering this kinetic energy that would otherwise be lost, the static pressure and total pressure efficiency of the fan are effectively improved. This means that with the same power consumption, the fan can provide a higher outlet pressure, or in other words, to achieve the same outlet pressure, the fan requires less power. Furthermore, since most ventilation and air conditioning systems use straight ducts with a desired axial airflow direction, if the fan outlet air... When air enters the pipe with a strong rotational state (large tangential component), it generates severe impact and friction with the pipe wall, leading to increased system resistance. This embodiment, by bending the volute outlet inward, can "pre-rectify" the airflow flowing from the volute into the outlet pipe, making the direction of the discharged airflow more parallel to the pipe axis. This greatly reduces the impact loss and eddy current generation when the airflow enters the pipe, making the flow of the entire ventilation system smoother and thus reducing the total pressure loss of the system. At the same time, the inward bending of the volute outlet can also "straighten" the airflow, providing a more uniform and stable outlet condition for the airflow, which helps protect downstream equipment and reduce system noise.

[0019] In some embodiments, the centrifugal fan also includes an outlet duct, which has an initial rectangular shape that is the same as the outlet shape of the volute, and an end shape that is elliptical, with a smooth lofted curve transitioning in the middle.

[0020] Since the cross-sectional dimensions, expansion angle, and smoothness of the internal flow channel of a centrifugal fan directly affect the airflow discharge effect, when the gas flows at the outlet, it generates frictional resistance with the inner wall of the outlet due to viscosity, forming a turbulent boundary layer. At the same time, if the outlet expansion angle is not designed properly, it will cause the airflow to separate at the outlet, forming a flow separation zone and causing a large amount of energy loss. In addition, if there is a sudden change in the connection between the outlet and the subsequent pipeline system, it will cause airflow impact and eddies, further aggravating energy loss, ultimately resulting in low overall aerodynamic efficiency of the centrifugal fan.

[0021] To solve the above problems, the present embodiment sets the starting shape of the air outlet pipe to be a rectangle and the same as the air outlet shape of the volute, sets the ending shape to be an ellipse, and uses a smooth lofting curve to transition in the middle, so that the sudden and discontinuous cross-sectional change at the connection can be avoided, which can cause sharp separation of airflow, strong vortex, and a large amount of energy loss. The present embodiment can gradually transition the rectangular outlet to an ellipse through the lofting curve, so that the airflow can be smoothly changed in direction and redistributed, so that the flow concentrated in the four corners of the rectangle is gradually increased to uniform flow in the ellipse, which effectively suppresses the separation of the airflow from the pipe wall, and further reduces the flow loss to a minimum. Moreover, the smooth flow means that the pulsation of the airflow pressure and speed is smaller, which directly leads to a lower level of aerodynamic noise and improves the acoustic environment. At the same time, in the scene where the installation space is limited, the flat elliptical pipe can save more installation height than the circular pipe with the same cross-sectional area, thereby leaving space for other pipelines.

[0022] In some embodiments, the internal curve of the air outlet pipe sets up four control points, the starting point coordinates corresponding to the connection point of the rectangle and the transition curve are P1, the ending point coordinates corresponding to the connection point of the ellipse and the transition curve are P4, P2 and P3 are intermediate control points, and the final transition curve is y(t) = (1-t) 3 ×P1+3(1-t) 2 ×t×P2+3(1-t)×t 2 ×P3+t 3 ×P4, where t ∈ [0, 1], P1 ∈ [0, 0], P2 ∈ [-103, -37], P3 ∈ [-122, -55], and P4 ∈ [-152, -57].

[0023] Firstly, the present embodiment uses a cubic curve to smoothly transition from a rectangle to an ellipse, which avoids sudden expansion or contraction of the airflow in the pipe, thereby significantly reducing the generation of airflow separation, vortex, and turbulence. Moreover, the careful setting of the coordinates of the control points P2 and P3 makes the change in the curvature of the curve facilitate the gradual redistribution of the airflow, so that the corner flow of the rectangle can smoothly transition to uniform flow in the ellipse, which reduces the local pressure loss and improves the total pressure efficiency and static pressure recovery capability of the fan. Secondly, at the P4 point (the ending point), the tangent direction of the curve is determined by the vector between P3 and P4 (about [-30, -2]), which is almost horizontal to the left, which makes the airflow smoothly enter the elliptical pipe, reduces the impact loss on the downstream pipe, reduces the system resistance, and makes the fan provide higher air volume or air pressure under the same power.

[0024] In some embodiments, the centrifugal fan further comprises a flow collector, and the flow collector is provided with a avoiding slot corresponding to at least one of the blade and the ring of the fan wheel.

[0025] The fitting precision between the collector and the impeller inlet, as well as the collector's own structural shape, significantly affect the airflow intake effect. Because of the velocity gradient of the gas entering the collector, and the unavoidable surface roughness of the collector's inner wall, a turbulent boundary layer forms on the collector's inner wall, causing flow losses before the airflow enters the impeller.

[0026] This application provides clearance grooves at at least one of the collector and the annulus of the blade and the impeller, thereby preventing the collector from contacting the blade and the annulus of the impeller even when the operating clearance is designed to be very small, thus minimizing internal leakage.

[0027] In some implementations, the inward folding angle φ of the volute's outlet is 7.88°±1°. This avoids situations where the angle is too small (e.g., <5°), resulting in weak guiding effect and inability to effectively change the airflow direction, causing a significant amount of tangential kinetic energy to be lost in the duct and poor static pressure recovery. It also avoids situations where the angle is too large (e.g., >12°), causing excessive compression and forced reversal of the airflow, leading to separation of the airflow from the wall, generating new vortices and energy loss, which is counterproductive. The 7.88°±1° angle range falls within a "sweet spot," providing sufficiently strong guiding effect to significantly change the airflow direction and recover kinetic energy, while being sufficiently gentle to minimize airflow separation. This allows the static pressure recovery efficiency to reach or approach its maximum value, thereby directly improving the fan's total pressure efficiency and static pressure efficiency.

[0028] In some implementations, the air outlet of the duct is a tapered outlet. This can reduce noise while increasing air pressure. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the blades of a wind turbine rotor according to an embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram of the blades of a wind turbine rotor from another perspective; Figure 3 This is a schematic diagram of the structure of a wind turbine impeller according to an embodiment of the present invention; Figure 4 for Figure 3 The diagram shows a cross-sectional view of the wind turbine rotor. Figure 5 This is a schematic diagram of the structure of a centrifugal fan according to an embodiment of the present invention; Figure 6 for Figure 5 A schematic diagram of the centrifugal fan from another perspective is shown; Figure 7 for Figure 6A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 8 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 5 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 9 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 8 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 10 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 8 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 11 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 5 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 12 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 11 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 13 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 5 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 14 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 15 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; Figure 16 A cross-sectional structure schematic view of the centrifugal fan along the A-A direction is shown in FIG. 1; The cross-sectional structure schematic view of the centrifugal fan according to the embodiment of the present application is shown in FIG. 1. The centrifugal fan comprises a fan wheel 20, a hub 22, a spoke 23, a circular ring 24, a volute 30, a bending structure 31, a second air outlet 32, a first opening 33, an air outlet duct 40, a first air inlet 41, a first air outlet 42, a first pivot shaft 43, a baffle 44, a current collector 50, a first cover plate 61, a second opening 611, a second cover plate 62, a motor 63, and a gap 64. DETAILED DESCRIPTION

[0030] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0031] It is also important to note that the use of relational terms such as first and second, and the like, are used solely to distinguish one from another entity or action without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", "includes", "including" and the like, are specifically intended to be open-ended. That is, when the specification uses one of these terms, the specification also contemplates the other possibilities. For example, the terms "comprises", "comprising", "includes", "including" and the like, use can be rephrased as "consisting essentially of", "consisting of", and the like. The term "consisting essentially of" is defined as including the elements listed after the term, and any additional elements that do not materially affect the basic and novel characteristics of the application. The term "consisting of" is defined as including the elements listed after the term and excluding any additional elements. The specification also contemplates the use of "open-ended" language, such as the terms "comprising", "having", "including", and the like, which are understood by one of ordinary skill in the art to mean that the recited elements can be present or absent, or that additional elements can be present, without materially affecting the basic and novel characteristics of the application. The use of such terms is meant to further stress that certain implementations of the application can omit, include, or substitute certain elements or features.

[0032] Also for the convenience of description, spatial relative terms such as "below", "under", "lower", "above", "upper" and the like, can be used herein for describing the relationship between one element or component and another element or component as shown in the drawings. The spatial relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial relative descriptors used herein interpreted accordingly.

[0033] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by one of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0034] Figure 1 and Figure 2 A blade 21 of a fan wheel 20 according to a first embodiment of the present application is exemplarily shown.

[0035] As shown in Figure 1 , the blade 21 of the fan wheel 20 is an equal-thickness blade 21, and a blade 21 profile of the blade 21 is fitted by a six-order curve function.

[0036] In some embodiments, the six-order curve function is y = -0.0002x6+0.0059x5-0.0867x4+0.6146x3-2.2099x2+3.4842x+10.92. In some embodiments, x ∈ [0, 17.38].

[0037] Since the blade 21 is a constant thickness blade 21, on the one hand, using a six-order curve function to fit the profile of the blade 21 can make the blade 21 have extremely high design freedom and enable the profile of the blade 21 to be accurately controlled: compared with low-order curves (such as quadratic, cubic, which have limited geometric characteristics), high-order six-order curves can not only control the curvature and the rate of change of the curvature (which is crucial for pressure distribution), but also can independently adjust the geometric characteristics of different regions (for example, the leading edge radius of the blade 21 can be independently optimized to improve the high angle of attack performance, while the trailing edge angle is maintained to control airflow separation), while being able to accurately fit the target blade profile; on the other hand, using a six-order curve function to fit the profile of the blade 21 can make the blade 21 have excellent aerodynamic performance: six-order curves can generate extremely smooth blade surface, avoiding the small discontinuous points that low-order curves may bring, thereby ensuring smooth transition of airflow, reducing frictional resistance and form resistance; on the other hand, six-order curves can very accurately describe the arrangement path and thickness distribution of the spar cap inside the blade 21, which allows the designer to thin the thickness of other regions as much as possible while ensuring sufficient structural strength in the key regions (such as the blade root); moreover, the super-high smoothness provided by high-order curves means a more gentle geometric transition, which helps to reduce stress concentration and improve the fatigue life of the blade 21.

[0038] In some preferred embodiments, as Figure 2As shown, the tail of the blade 21 is provided with a chamfer structure 211. When the chamfer structure 211 is provided at the position of the blade 21, the formation concept of the tip vortex is changed, and the chamfer structure 211 disperses a concentrated and strong vortex into multiple smaller and weaker vortexes; at the same time, the chamfer makes the positions where the edge of the blade 21 meets the flow stagger in time, reducing the pulsed pressure pulsation, so that the noise can be significantly reduced; in addition, the chamfer structure 211 can also be equivalent to a "load softening" structure; when a strong wind hits the blade 21, the chamfered part does not simultaneously transmit the load to the root, but has a slight delay and dispersion effect; this reduces the peak value of the dynamic load and smooths the torque output, thereby reducing the fatigue load and ultimate load borne by the blade 21 root, the hub 22 and the transmission chain, so that a lighter blade 21 and support structure can be designed, or the service life of the entire fan can be extended. In some preferred embodiments, the angle of the chamfer structure 211 is 45°±5°. The inventors found in the research process that the chamfer angle does not have a linear effect on noise reduction. The noise reduction effect is very obvious when the angle is increased from 0°. However, when the angle increases to a certain extent (such as 45°-50°), the increase in noise reduction benefit will no longer be significant; and too large a chamfer angle (for example, more than 60°) will have obvious negative effects: for example, the effective wind sweeping area of the blade 21 will be reduced, and unnecessary induced drag will be introduced, reducing the wind energy capture efficiency; for another example, a too large chamfer angle will produce a significant bending-torsion coupling effect, which may cause unpredictable vibration problems and require higher structural strength.

[0039] Figure 3 and Figure 4 An example of a fan wind wheel 20 according to a first embodiment of the application is shown.

[0040] As Figure 3 shown, the fan wind wheel 20 includes the blade 21 of the aforementioned fan wind wheel 20. Since the blade 21 of the wind wheel 20 is an equal-thickness blade 21, and the airfoil shape is fitted by a six-order curve function, the airflow noise caused by the traditional blade 21 composed of multiple line segments is avoided; and the problem that the airflow cannot flow smoothly caused by a single circular-arc blade 21 is also avoided.

[0041] In some embodiments, as Figure 4 shown, the fan wind wheel 20 further includes a hub 22, a spoke 23 and a circular ring 24, and the blade 21, the hub 22, the spoke 23 and the circular ring 24 are integrally formed. In this way, stress concentration and fatigue crack sources caused by welding or bolt connection are avoided; the problem of increased fluid resistance caused by welds and bolts is avoided; and the structure is maximally simplified. In some embodiments, at least one of the hub 22, the spoke 23, the circular ring 24 and the blade 21 is made of plastic material.

[0042] In some preferred embodiments, with continued reference to Figure 4 As shown, the diameter of the annular ring 24 is slightly larger than the outer diameter of the blade 21. This embodiment sets the annular ring 24 on the blade 21 and sets the diameter of the annular ring 24 to be slightly larger than the outer diameter of the blade 21, which is equivalent to setting a physical barrier "upstream" of the tip clearance 64. It forces the leakage flow to take a longer and more tortuous path to leak back, greatly increasing the flow resistance of the leakage flow, thereby improving the volumetric efficiency and overall aerodynamic efficiency of the fan, while suppressing tip leakage and flow separation, and weakening the above-mentioned noise generation mechanism from the source; this embodiment plays a "guiding" and "restricting" role on the airflow entering the channel of the blade 21 through the slightly larger annular ring 24, which can guide the airflow to enter the tip region more smoothly, and delay or eliminate the flow separation at the leading edge of the blade 21 by restricting the flow field near the wall area; in addition, this extended annular ring 24 plays a role of "reinforcing ring" in structure, which connects the tip parts of all blades 21 together to form a closed ring structure, significantly improving the overall structural stiffness and anti-deformation ability of the impeller.

[0043] In some embodiments, the number of blades 21 is odd to avoid resonance problems caused by even number of blades 21 and reduce aerodynamic noise. In some embodiments, the number of blades 21 is greater than 35.

[0044] In some embodiments, as shown in Figure 4 The hub 22 is a conical frustum, for example. The diameter of the hub 22 gradually decreases from the inlet side of the impeller to the middle side of the impeller. Since the conical frustum can provide a smooth and gradual guide surface, the airflow can flow along the inclined surface of the cone and gradually transition from axial flow to radial flow of the impeller, which significantly reduces the impact and separation loss at the inlet, so that the airflow can enter the flow passage between the blades 21 more "obediently"; moreover, the conical frustum structure can better match the absolute velocity distribution of the inlet and the peripheral velocity distribution of the impeller, thereby reducing the attack angle between the inlet airflow and the blades 21, achieving "non-impact inlet" or close to non-impact inlet, which directly improves the efficiency of the fan; at the same time, the conical frustum structure as a transition form has a more smooth shape change, which can more evenly transmit the centrifugal force and aerodynamic force transmitted by the blades 21 to the main shaft and bearings, reduce stress concentration, and improve the fatigue life of the structure.

[0045] Figures 5 to 13 The centrifugal fan of the first embodiment of the present application is exemplarily shown.

[0046] As shown in Figures 9 to 13As shown, the centrifugal fan includes the aforementioned fan blade 21 of the fan wheel 20; or includes the aforementioned fan wheel 20. Since the fan blade 21 of the fan wheel 20 is an equal-thickness blade 21 and the blade type is fitted by a six-time curve function, the airflow noise caused by the traditional blade 21 composed of multiple line segments is avoided; and the problem that the airflow cannot flow smoothly caused by the single circular-arc blade 21 is also avoided.

[0047] In some embodiments, as shown, Figures 5 to 7 As shown, the centrifugal fan further includes a volute 30. As shown, Figure 7 As shown, a bending structure 31 is arranged at the air outlet of the volute 30, and the bending direction is inward. In this embodiment, the originally outward flowing airflow is turned inward by the inward bending treatment of the air outlet of the volute 30, and becomes a flow closer to the axial direction. In this forced turning process, the tangential velocity component of the airflow is reduced, and the corresponding kinetic energy is recovered and converted into additional static pressure. By recovering this part of the originally lost kinetic energy, the static pressure and total pressure efficiency of the fan are effectively improved. This means that under the condition of consuming the same power, the fan can provide higher outlet pressure, or in other words, in order to achieve the same outlet pressure, the fan requires less power. Moreover, since most of the ducts of the ventilation and air conditioning system are straight ducts, the expected airflow direction is axial. If the fan outlet airflow enters the duct in a strong rotating state (large tangential component), it will produce violent impact and friction with the duct wall, resulting in increased system resistance. In this embodiment, the inward bending treatment of the air outlet of the volute 30 can "pre-straighten" the airflow flowing from the volute 30 into the air outlet duct 40, so that the direction of the discharged airflow is more parallel to the duct axis. This greatly reduces the impact loss and vortex generation when the airflow enters the duct, making the flow of the entire ventilation system more smooth, thereby reducing the system total pressure loss. At the same time, the inward bending treatment of the outlet of the volute 30 can also "straighten" the airflow, providing an outlet condition with a more uniform and stable flow field. This helps to protect downstream equipment and reduce system noise. In some preferred embodiments, the inward bending angle φ of the air outlet of the volute 30 is 7.88°±1°, so as to avoid that the angle is too small (such as <5°) and the flow guiding effect is too weak, so that the airflow direction cannot be effectively changed, and a large amount of tangential kinetic energy is still lost in the duct, and the static pressure recovery effect is poor; and also to avoid that the angle is too large (such as >12°) and the airflow is excessively squeezed and forced to turn, causing the airflow to separate from the wall and produce new vortex and energy loss, which is not worth the cost. The angle range of 7.88°±1° is in a "sweet spot area", which provides a strong flow guiding effect to significantly change the airflow direction and recover kinetic energy; at the same time, it is gentle enough to maximize the avoidance of airflow separation; this makes the efficiency of static pressure recovery reach or approach the maximum value, thereby directly improving the total pressure efficiency and static pressure efficiency of the fan.

[0048] In some embodiments, as shown,Figures 5 to 8 , Figures 10 to 13 As shown, the centrifugal fan also includes an outlet duct 40. (As indicated...) Figure 5 , Figure 11 and Figure 12 As shown, the initial shape of the air outlet pipe 40 is rectangular (i.e., the first air inlet 41) and the same as the air outlet shape of the volute 30. The final shape is elliptical (i.e., the first air outlet 42), with a smooth lofted curve transition in the middle. In this embodiment, the initial shape of the outlet duct 40 is set to be rectangular and the same as the shape of the outlet of the volute 30 (i.e., the second outlet 32), and the final shape is set to be elliptical. A smooth lofted curve is used for transition in the middle, which can avoid the formation of a sudden and discontinuous cross-sectional change at the connection, which would cause the airflow to separate sharply, generate strong eddies, and cause a large amount of energy loss. In this embodiment, by making the rectangular outlet gradually transition to an elliptical shape through a lofted curve, the airflow can be guided to change direction and redistribute smoothly, so that the flow concentrated in the four corner areas of the rectangle is gradually increased to a uniform elliptical flow, which effectively suppresses the separation of airflow from the pipe wall and thus minimizes flow loss. Moreover, the smooth flow means less pulsation of airflow pressure and velocity, which directly leads to a lower aerodynamic noise level and improves the acoustic environment. At the same time, in scenarios where the installation space is limited, the flat elliptical pipe can save more installation height than a circular pipe of the same cross-sectional area, thus leaving space for other pipelines. In some preferred embodiments, four control points are established within the internal curve of the air outlet duct 40. The starting point coordinates correspond to the connection point between the rectangle and the transition curve, which is P1. The ending point coordinates correspond to the connection point between the ellipse and the transition curve, which is P4. P2 and P3 are intermediate control points. The final transition curve is y(t) = (1-t)³×P1 + 3(1-t)²×t×P2 + 3(1-t)×t²×P3 + t³×P4, where t∈[0,1], P1∈[0,0], P2∈[-10³,-37], P3∈[-12²,-55], and P4∈[-15²,-57]. (The positions of points P1, P2, P3, and P4 are as follows: ...) Figure 16As shown in FIG. 1, the transition curve of the present embodiment is a smooth transition from a rectangle to an ellipse, which avoids sudden expansion or contraction of the airflow in the pipeline, thereby significantly reducing the generation of airflow separation, vortex and turbulence; moreover, the careful setting of the coordinates of the control points P2 and P3 makes the change of the curve curvature facilitate the gradual redistribution of the airflow, so that the corner flow of the rectangle can smoothly transition to the uniform flow of the ellipse, which reduces the local pressure loss and improves the total pressure efficiency and static pressure recovery capacity of the fan; in addition, at the P4 point (the end point), the tangent direction of the curve is determined by the vector between P3 and P4 (about [-30, -2]), which is almost horizontal to the left, which makes the airflow smoothly enter the elliptical pipeline, reduces the impact loss on the downstream pipeline, reduces the system resistance, and makes the fan provide higher air volume or air pressure under the same power. In some embodiments, the outlet of the outlet pipeline 40 is a tapered outlet to improve the air pressure while reducing noise.

[0049] In some embodiments, as shown in FIG. 2, the centrifugal fan further comprises a flow collector 50, and the flow collector 50 is provided with a clearance groove 51 corresponding to at least one of the blade 21 and the circular ring 24 of the fan wheel 20. Figures 9 to 13 In some embodiments, as shown in FIG. 2, the centrifugal fan further comprises a flow collector 50, and the flow collector 50 is provided with a clearance groove 51 corresponding to at least one of the blade 21 and the circular ring 24 of the fan wheel 20.

[0050] In some embodiments, as shown in FIG. 2, the centrifugal fan further comprises a flow collector 50, and the flow collector 50 is provided with a clearance groove 51 corresponding to at least one of the blade 21 and the circular ring 24 of the fan wheel 20. Figure 5 Figure 6 Figures 9 to 12 In some embodiments, as shown in FIG. 2, the centrifugal fan further comprises a first cover plate 61, which is fixedly arranged relative to the volute 30, the volute 30 has a first opening 33 for taking and placing the flow collector 50, and the first cover plate 61 covers the first opening 33; the first cover plate 61 has a second opening 611 for communicating the first opening 33 with the outside.

[0051] In some embodiments, as shown in FIG. 2, the centrifugal fan further comprises a first cover plate 61, which is fixedly arranged relative to the volute 30, the volute 30 has a first opening 33 for taking and placing the flow collector 50, and the first cover plate 61 covers the first opening 33; the first cover plate 61 has a second opening 611 for communicating the first opening 33 with the outside. Figure 5 Figure 6 Figure 9 Figure 10 In some embodiments, as shown in FIG. 2, the centrifugal fan further comprises a second cover plate 62, which is fixedly arranged relative to the first cover plate 61, the second cover plate 62 is arranged on the side of the first cover plate 61 away from the flow collector 50, and there is a gap 64 between the second cover plate 62 and the first cover plate 61 for communicating the second opening 611 with the outside.

[0052] In some embodiments, as shown in FIG. 2, the centrifugal fan further comprises a second cover plate 62, which is fixedly arranged relative to the first cover plate 61, the second cover plate 62 is arranged on the side of the first cover plate 61 away from the flow collector 50, and there is a gap 64 between the second cover plate 62 and the first cover plate 61 for communicating the second opening 611 with the outside. Figure 9 ​​​​​​Figure 11 and Figure 12 As shown in FIG. 1, the centrifugal fan further comprises a motor 63, a base of the motor 63 is mounted on the volute 30, and a rotating shaft of the motor 63 is used to drive the impeller 20 to rotate coaxially.

[0053] In some embodiments, as shown in FIG. 2, the first air outlet 42 of the air outlet pipe 40 is further provided with a wind baffle 44 which can rotate around a first pivot axis 43, so as to avoid the influence of external wind force on the gas flow in the volute 30. Figure 5 and Figure 11 As shown in FIG. 2, the first air outlet 42 of the air outlet pipe 40 is further provided with a wind baffle 44 which can rotate around a first pivot axis 43, so as to avoid the influence of external wind force on the gas flow in the volute 30.

[0054] The impeller 20 for the fan of the present application is described below in combination with specific embodiments.

[0055] Embodiment 1 The number of blades 21 is n=45; the outer diameter of the impeller R1 is 178 mm; the inner diameter of the impeller R2 is 146 mm; the axial height of the hub 22 H1 is 66.7 mm; the diameter of the bottom of the circular cone of the hub 22 r1 is 120 mm; the diameter of the top of the hub 22 r2 is 70 mm; the gap 64T1 between the top connecting ring 24 of the impeller and the flow collector 50 is 4 mm; the thickness of the ring 24 T2 is 1.5 mm; the depth of the avoidance groove 51 T3 is T1; the blade 21 adopts a six-order curve function y=-0.0002x6+0.0059x5-0.0867x4+0.6146x3-2.2099x2+3.4842x+10.92 fitting, x∈[0, 17.38]; the tail of the blade 21 is provided with a bevel structure 211, the angle of the bevel structure 211 is 45°±5°; the air outlet of the volute 30 is provided with a bending structure 31, the bending direction is inward, and the inward angle φ is 7.88°±1°; the initial shape of the air outlet pipe 40 is a rectangle and is the same as the shape of the air outlet of the volute 30, the final shape is an ellipse, and a smooth spline curve is used for transition in the middle; four control points are set on the internal curve of the air outlet pipe 40, the starting point coordinates corresponding to the connection point of the rectangle and the transition curve are P1, the ending point coordinates corresponding to the connection point of the ellipse and the transition curve are P4, P2 and P3 are intermediate control points, and the final transition curve is y(t)=(1-t)3×P1+3(1-t)2×t×P2+3(1-t)×t2×P3+t3×P4, wherein t∈[0, 1], P1∈[0, 0], P2∈[-103, -37], P3∈[-122, -55], and P4∈[-152, -57].

[0056] Comparative Example 1 The number of blades 21 is n=45; the outer diameter of the impeller R1=178mm; the inner diameter of the impeller R2=146mm; the axial height of the hub 22 H1=66.7mm; the bottom diameter of the hub 22 r1=120mm; the top diameter of the hub 22 r2=70mm; the gap 64T1 between the top connecting ring 24 and the flow collector 50 is 4mm; the thickness of the ring 24 T2=1.5mm; the depth of the avoiding groove 51 T3=T1; the blade 21 adopts a six-time curve function y=-0.0002x6+0.0059x5-0.0867x4+0.6146x3-2.2099x2+3.4842x+10.92 fitting, x∈[0, 17.38]; the tail of the blade 21 is provided with a bevel structure 211, and the angle of the bevel structure 211 is 45°±5°; the outlet of the volute 30 is provided with a bending structure 31, the bending direction is inward, and the inward angle φ is 7.88°±1°; the initial shape of the outlet pipeline 40 is a rectangle and is the same as the outlet shape of the volute 30, the final shape is an ellipse, and a smooth spline curve is used for transition in the middle; four control points are set on the internal curve of the outlet pipeline 40, the starting point coordinates correspond to the connecting point of the rectangle and the transition curve P1, the ending point coordinates correspond to the connecting point of the ellipse and the transition curve P4, P2 and P3 are intermediate control points, and the final transition curve is y(t)=(1-t)3×P1+3(1-t)2×t×P2+3(1-t)×t2×P3+t3×P4, wherein t∈[0, 1], P1∈[0, 0], P2∈[-103, -37], P3∈[-122, -55], and P4∈[-152, -57].

[0057] Compared with the original shape, the impeller designed in the application uses a plurality of circular arc blades 21, adopts a six-time function fitting, the flow resistance in the flow passage is smaller, the flow pressure distribution is more uniform, the outlet of the volute 30 adopts a bevel, and the pressure pulsation at the outlet bevel position is obviously lower than that of the original shape, for details, see the streamline diagram of the impeller of the application embodiment 1 and the streamline diagram of the impeller of the comparative example 1. Figure 15 Figure 14

[0058] According to the actual measurement, compared with the original prototype, the air volume of the fan produced according to the application is increased from 167.53m / h to 182.02m / h, and the noise is reduced from 38.17dB to 35.07dB.

[0059] In the application, the connection or mounting is fixed connection without special emphasis. The fixed connection can be realized as detachable connection or non-detachable connection commonly used in the prior art. The detachable connection can be realized by using the prior art, such as threaded connection or key connection. The non-detachable connection can also be realized by using the prior art, such as welding or gluing.

[0060] ​​The above merely describes some embodiments of the present application. For those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the protection scope of the present application.

Claims

1. The blades of a wind turbine impeller, characterized in that, The blade is of uniform thickness, and the blade profile is obtained by fitting a sixth-order curve function.

2. The blades of the wind turbine impeller according to claim 1, characterized in that, The sixth-order curve function is y = -0.0002x. 6 +0.0059x 5 -0.0867x 4 +0.6146x 3 -2.2099x 2 +3.4842x+10.92; and / or The tail of the blade is provided with an oblique cut structure.

3. The blades of the wind turbine impeller according to claim 2, characterized in that, The angle of the oblique cut structure is 45°±5°; and / or x∈[0,17.38].

4. A wind turbine impeller, characterized in that, Includes the blades of the wind turbine rotor as described in any one of claims 1 to 3.

5. The wind turbine impeller according to claim 4, characterized in that, It also includes a hub, spokes, and annulus, wherein the blades, hub, spokes, and annulus are integrally formed; and / or The number of blades is odd.

6. The wind turbine impeller according to claim 5, characterized in that, The wheel hub is truncated cone-shaped.

7. A centrifugal fan, characterized in that, Includes the blades of a wind turbine rotor as described in any one of claims 1 to 3; or Includes the wind turbine rotor as described in any one of claims 4 to 6.

8. The centrifugal fan according to claim 7, characterized in that, It also includes a volute, with a bent structure at the air outlet of the volute, the bending direction being inward; and / or It also includes an air outlet duct, which has a rectangular initial shape that is the same as the air outlet shape of the volute, and an elliptical final shape with a smooth lofted curve transition in the middle.

9. The centrifugal fan according to claim 8, characterized in that, Four control points are set inside the air outlet duct curve. The starting point coordinates correspond to the connection point between the rectangle and the transition curve, which is P1. The ending point coordinates correspond to the connection point between the ellipse and the transition curve, which is P4. P2 and P3 are intermediate control points. The final transition curve is y(t)=(1-t). 3 ×P1+3(1-t) 2 ×t×P2+3(1-t)×t 2 ×P3+t 3 ×P4, where t∈[0,1], P1∈[0,0], P2∈[-103,-37], P3∈[-122,-55], P4∈[-152,-57]; and / or It also includes a collector ring, wherein at least one of the collector ring and the annulus of the blade and the impeller of the wind turbine is provided with a clearance groove.

10. The centrifugal fan according to claim 9, characterized in that, The inward folding angle φ of the air outlet of the volute is 7.88°±1°; and / or The air outlet of the air outlet duct is a tapered outlet.

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