CN118815748A - An axial flow impeller - Google Patents

Abstract

The present invention relates to an axial flow impeller, which comprises a fixing ring, a hub and a plurality of blades. The hub is arranged in the fixing ring and is coaxial with the hub. The plurality of blades are arranged between the hub and the fixing ring and are spaced apart along the circumference of the hub. The blade has a blade root connected to the hub, a blade top corresponding to the blade root and connected to the fixing ring, a leading edge facing the impeller rotation direction and located on one side of the blade root, a trailing edge away from the impeller rotation direction and located on the other side of the blade root, a pressure surface facing the wind outlet direction and a suction surface corresponding to the pressure surface, and a gradually changing amplitude corrugation is arranged near the blade top of the blade. By adopting a blade with a gradually changing amplitude corrugation, the velocity on the pressure surface, as well as the velocity pulsation and pressure fluctuation at the trailing edge are effectively reduced, thereby reducing noise. By arranging corrugations near the blade top of the blade, the blade can be made through a mold, the processing is easier, the processing accuracy is higher and the fan performance will not be changed.

Description

An axial flow impeller

Technical Field

The present invention relates to the technical field of fans, and in particular to an axial flow impeller.

Background Art

The blades of traditional axial fans are smooth straight lines or curves at the leading and trailing edges, which will cause serious flow separation on the blade surface, forming secondary flow, backflow and vortex, and the noise will be very loud at high speeds. In terms of the research and application of rotating machinery noise, a lot of research has been done on the leading and trailing edges of blade shapes. For example, the use of NACA airfoil blades, various types of sawtooth designs at the leading and trailing edges, especially the bionic sawtooth design at the trailing edge, can effectively reduce the noise of the fan. However, adding a sawtooth-shaped structure to the trailing edge, such as a sinusoidal, iron-shaped or triangular conventional sawtooth shape, due to the thin thickness of the trailing edge itself, coupled with the flat structure of the sawtooth shape and the pointed shape of the sawtooth end, there are problems of difficulty in processing and poor processing accuracy during mold processing and manufacturing, and the blade may break during operation. There are also manufacturers who, based on the existing smooth trailing edge, observe the internal flow conditions through simulation, and then manually cut the blades to achieve the purpose of adding a trailing edge to reduce noise. Although cutting the blades can reduce noise, this practice will also change the performance of the fan and bring other uncertainties.

Summary of the invention

The object of the present invention is to provide an axial flow impeller, which can effectively reduce the velocity magnitude on the pressure surface, the velocity pulsation and the pressure fluctuation at the trailing edge by adopting blades with gradually varying amplitude corrugations, thereby reducing noise. By providing corrugations near the blade tip, the blade can be made through a mold, which makes processing easier, with higher processing accuracy and without changing the fan performance.

To achieve the above object, the present invention provides an axial flow impeller, comprising:

Fixed ring;

A wheel hub, disposed in the fixing ring and coaxial with the wheel hub;

A plurality of blades are arranged between the hub and the fixing ring and are spaced apart along the circumference of the hub, wherein the blades have a blade root connected to the hub, a blade top corresponding to the blade root and connected to the fixing ring, a leading edge facing the rotation direction of the impeller and located on one side of the blade root, a trailing edge away from the rotation direction of the impeller and located on the other side of the blade root, a pressure surface facing the air outlet direction and a suction surface corresponding to the pressure surface, and the blades are provided with corrugations with gradually varying amplitudes near the blade tops.

Optionally, the blade is recessed inwardly near the blade top along the direction from the leading edge to the trailing edge to form a plurality of spaced grooves, and a single protrusion is protruded outwardly along the direction from the leading edge to the trailing edge between two adjacent grooves, and the grooves and the protrusions cooperate to form the corrugations, and the amplitude of the corrugations gradually increases along the direction from the blade root to the blade top and along the direction from the leading edge to the trailing edge.

Optionally, the corrugations are arranged from a preset position to a blade top, and a ratio of a distance from the preset position to the blade root to a distance from the blade root to the blade top is in a range of 0.5625-0.6785.

Optionally, the projection profile of the leading edge on the meridian plane is a parabola, and the parabola is expressed by the following formula:

y＝Ax ² +Bx

Among them, y is the first coordinate of the point on the parabola on the meridian plane, x is the second coordinate of the point on the parabola on the meridian plane, and A and B are first coefficients.

Optionally, the leading edge and the blade root form a first intersection, the leading edge and the blade top form a second intersection, the parabola passes through the first intersection and the second intersection, the difference between the first coordinates of the first intersection and the second intersection is in the range of 105-110, and the difference between the second coordinates of the first intersection and the second intersection is in the range of 75-80.

Optionally, the projection profile of the trailing edge on the meridian plane is a straight line, the angle between the straight line and the radial surface of the hub is 0°-10°, and the end of the straight line away from the hub is oriented toward the parabola direction.

Optionally, the blade is cut along the radial direction by a circle concentric with the radial surface of the hub to form a plurality of cross-sections, the cross-section having a midline along the direction from the leading edge to the trailing edge, a plurality of tangent points are arranged at intervals on the midline, a connecting line is formed between the tangent point and a preset point on the center axis of the hub, the angle between the connecting line and the radial surface of the hub forms a cross-section angle, and a plurality of the cross-section angles cooperate with each other to determine the shape of the cross-section.

Optionally, the cut surface angle is expressed by the following formula:

y＝ax ⁶ +bx ⁵ +cx ⁴ +dx ³ +ex ² +fx+g

Among them, y is the cutting angle, x is the distance from the tangent point to the intersection of the median line and the leading edge, and a, b, c, d, e, f and g are second coefficients.

Optionally, the second coefficients a, c, e and f gradually increase from a first preset section to the blade top, and the second coefficients b and d gradually decrease from the first preset section to the blade top, and the first preset section is the preset point.

Optionally, the second coefficient g remains unchanged from the blade root to the second preset section, and gradually increases from the second preset section to the blade top, and the ratio of the distance from the second preset section to the blade root to the distance from the blade root to the blade top is in the range of 0.7-0.8.

The beneficial effect of the present invention is that by adopting blades with gradually changing amplitude corrugations, the velocity magnitude on the pressure surface, as well as the velocity pulsation and pressure fluctuation at the trailing edge are effectively reduced, thereby reducing noise. By providing corrugations near the blade tip, the blade can be made through a mold, which makes processing easier, with higher processing accuracy and without changing the fan performance.

The blade shape is generated by adjusting the projected profiles of the leading edge and trailing edge on the meridian plane and the section angles at different radii of the blade, thereby optimizing the aerodynamic performance of the blade, improving the airflow state, reducing noise, and increasing structural strength and durability.

The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of an axial flow impeller according to an embodiment of the present invention;

FIG2 is a schematic structural diagram of a blade of an axial flow impeller shown in an embodiment of the present invention;

FIG3 is a schematic structural diagram of the projection profiles of the leading edge and the trailing edge of a blade of an axial flow impeller on a meridian plane according to an embodiment of the present invention;

FIG4 is a schematic structural diagram showing the formation of a tangent angle of a blade of an axial flow impeller according to an embodiment of the present invention;

FIG5 is a schematic diagram of wind speed distribution simulation of an axial flow impeller according to an embodiment of the present invention;

In the figure: 1, fixing ring; 2, hub; 3, blade; 31, blade root; 32, blade top; 33, leading edge; 34, trailing edge; 35, pressure surface; 36, suction surface; 37, corrugation; 371, groove; 372, protrusion; 4, meridian plane; 41, parabola; 411, first intersection point; 412, second intersection point; 42, straight line; 5, section; 51, connecting line.

DETAILED DESCRIPTION

The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

Please refer to Figures 1 and 2. An axial flow impeller shown in a preferred embodiment of the present application includes a fixing ring 1, a hub 2 and a plurality of blades 3. The hub 2 is arranged in the fixing ring 1 and is coaxial with the hub 2. The plurality of blades 3 are arranged between the hub 2 and the fixing ring 1 and are spaced apart along the circumference of the hub 2. The blade 3 has a blade root 31 connected to the hub 2, a blade tip 32 corresponding to the blade root 31 and connected to the fixing ring 1, a leading edge 33 facing the impeller rotation direction and located on one side of the blade root 31, a trailing edge 34 away from the impeller rotation direction and located on the other side of the blade root 31, a pressure surface 35 facing the wind outlet direction and a suction surface 36 corresponding to the pressure surface 35, and a ripple 37 with a gradually changing amplitude is arranged near the blade tip 32 of the blade 3.

When the impeller rotates around the rotation axis, the speed at the blade tip 32 is the largest, and the speed decreases as the radius decreases. Therefore, improving the flow state of the blade 3 near the blade tip 32 is the key to improving the performance and noise of the fan. Therefore, according to the solution of the embodiment of the present invention, by adopting the blade 3 with a gradually changing amplitude corrugation 37, the speed on the pressure surface 35, as well as the speed pulsation and pressure fluctuation at the trailing edge 34 are effectively reduced, thereby reducing noise. By providing the corrugation 37 near the blade tip 32 of the blade 3, the blade 3 can be made by a mold, which is easier to process, has higher processing accuracy and does not change the performance of the fan.

It should be noted that the fixing ring 1 is an annular structure connected to the blade top 32 to prevent the blade 3 from being greatly deformed during operation at a high speed, and the leading edge 33 first contacts the medium in the direction of rotation of the impeller, from the blade root 31 to the blade top 32 on one side, and the trailing edge is in the direction of rotation of the impeller, where the medium leaves the blade 3 and goes from the blade root 31 to the blade top 32 on the other side.

The following is a detailed description with specific embodiments:

Please refer to FIG. 2 . The blade 3 is concave inwards near the blade top 32 along the direction from the leading edge 33 to the trailing edge 34 to form a plurality of spaced grooves 371. A single protrusion 372 is protruded outwards along the direction from the leading edge 33 to the trailing edge 34 between two adjacent grooves 371. The grooves 371 and the protrusions 372 cooperate to form a corrugation 37. The amplitude of the corrugation 37 gradually increases along the direction from the blade root 31 to the blade top 32 and along the direction from the leading edge 33 to the trailing edge 34. The change in the amplitude of the corrugation 37 includes two directions. One is from the direction from the leading edge 33 to the trailing edge, where the single groove 371 and the protrusion 372 gradually change from gentle to increased depth; the other is from the direction from the blade root 31 to the blade top 32, where the crests and troughs of the entire corrugation 37 gradually increase. In this embodiment, the number of blades 3 is 7.

The corrugation 37 is arranged from the preset position to the blade tip 32, and the ratio of the distance from the preset position to the blade root 31 to the distance from the blade root 31 to the blade tip 32 is in the range of 0.5625-0.6785. That is, in this embodiment, the position of the corrugation 37 is defined by the position at different radii of the blade 3. In this embodiment, the blade root 31 is set as 0, and the blade tip 32 is set as 1, and the blade 3 is provided with a corrugation 37 with a gradually increasing amplitude from 0.625-1. From the pressure surface 35, the wrap angle of the blade 3 at 0.625-1 gradually increases. It should be noted here that the wrap angle is a plane perpendicular to the center axis of the hub 2. The line from the first projection point of the target position of the leading edge 33 on the plane to the intersection of the plane and the center line of the hub 2 (i.e., the center) is the first wrap angle line, and the line from the second projection point of the target position of the trailing edge 34 on the plane to the intersection of the plane and the center axis of the hub 2 (i.e., the center) is the second wrap angle line. The angle between the first wrap angle line and the second wrap angle line is the wrap angle ɑ, as shown in Figure 2. The selection of the first projection point and the second projection point is based on the wrap angle being able to cover the entire target part of the blade 3. The larger the wrap angle, the greater the angle of attack of the blade 3 in the outer area, which enables the blade 3 to more effectively utilize the high-speed airflow. The increase in the angle of attack helps to increase the thrust of the blade 3 at a high radial position. When the blade 3 shape of the gradual corrugation 37 is adopted, the load distribution at 0.75-1 on the blade 3 can be uniform, and the maximum pressure and speed on the entire pressure surface 35 can be reduced. When the speed is low, the boundary layer thickness can be increased, and its separation can be delayed, thereby reducing the vortex, reducing the vortex separation, and effectively improving the noise level. When the blade 3 of the present application is adopted, compared with the noise of the blade 3 without the corrugation 37 structure, the noise value of the axial flow fan using the blade 3 of the present application can be reduced by 1.7dB. Please refer to Figure 5, it can be seen that after adopting the design of the blade 3 of the present application, the air flow velocity distribution on the impeller blade 3 is more uniform, so that better noise reduction can be performed.

Please refer to FIG. 3 . Specifically, the projection profile of the leading edge 33 on the meridian plane 4 is a parabola 41. The parabola 41 is expressed by the following formula:

y＝Ax ² +Bx

Wherein, y is the first coordinate of the point on the parabola 41 on the meridian plane 4, x is the second coordinate of the point on the parabola 41 on the meridian plane 4, and A and B are first coefficients. It should be noted that the meridian plane 4 is a plane perpendicular to the center axis of the hub 2 and passes through the center axis of the hub 2.

Please refer to Fig. 3. In this embodiment, the intersection of the leading edge 33 and the blade root 31 forms a first intersection 411, the intersection of the leading edge 33 and the blade tip 32 forms a second intersection 412, the parabola 41 passes through the first intersection 411 and the second intersection 412, the difference between the first coordinates of the first intersection 411 and the second intersection 412 ranges from 105 to 110, and the difference between the second coordinates of the first intersection 411 and the second intersection 412 ranges from 75 to 80. By determining the coordinate difference between the first intersection 411 and the second intersection 412, when a two-dimensional coordinate system is determined on the meridian plane 4, the specific coordinates of the first intersection 411 and the second intersection 412 can be determined, so that the first coefficients A and B can be obtained by bringing them into the formula of the parabola 41, and then the projection profile of the leading edge 33 on the meridian plane 4 is determined. Specifically, in this embodiment, the two-dimensional coordinate system is established with the central axis of the hub 2 as the second coordinate axis, and a straight line parallel to the radial surface of the hub 2 as the first coordinate axis (the radial surface of the hub 2 is a plane in the radial direction of the hub 2), and the first coordinate axis intersects with the projection profile of the leading edge 33 on the meridian plane 4. In this embodiment, the projection profile of the trailing edge 34 on the meridian plane 4 is a straight line 42, and the angle between the straight line 42 and the radial surface of the hub 2 is 0°-10°, and the end of the straight line 42 away from the hub 2 is toward the direction of the parabola 41.

Please refer to Figure 4. The blade 3 is cut along the radial direction by a circle concentric with the radial surface of the hub 2 to form a plurality of cut surfaces 5. The cut surface 5 has a median line along the direction from the leading edge 33 to the trailing edge 34. A plurality of tangent points are arranged at intervals on the median line. A connecting line 51 is formed between the tangent point and a preset point on the central axis of the hub 2. The angle between the connecting line 51 and the radial surface of the hub 2 forms a cut surface angle. A plurality of cut surface angles cooperate with each other to determine the shape of the cut surface 5. It should be noted that the distance from the cut surface 5 to the center of the radial surface of the hub 2 is the radius of the cut surface 5. The median line is defined as a line with equal distances to the edges of the cut surface 5 on both sides thereof. In other words, the shape of a cut surface 5 requires the determination of multiple cut surface angles to be generated.

Specifically, the cut surface angle is expressed by the following formula:

y＝ax ⁶ +bx ⁵ +cx ⁴ +dx ³ +ex ² +fx+g

Wherein, y is the tangent angle, x is the distance from the tangent point to the intersection of the median line and the leading edge 33, and a, b, c, d, e, f and g are the second coefficients. The second coefficients a, c, e and f gradually increase from the first preset tangent plane 5 to the blade top 32, and the second coefficients b and d gradually decrease from the first preset tangent plane 5 to the blade top 32. The first preset tangent plane 5 is a preset point, and the second coefficients a, b, c, d, e, f change slightly from the blade root 31 to the first preset tangent plane 5. The second coefficient g remains unchanged from the blade root 31 to the second preset tangent plane 5, and the second coefficient g gradually increases from the second preset tangent plane 5 to the blade top 32. The ratio of the distance from the second preset tangent plane 5 to the blade root 31 to the distance from the blade root 31 to the blade top 32 is in the range of 0.7-0.8. It should be noted here that the change of the second coefficient is also defined by the position of the blade 3 at different radii. Specifically, in this embodiment, the blade root 31 is set to 0, and the blade top 32 is set to 1, then the second coefficients a, c, e and f of the section angle of the section 5 of the blade 3 at 0.625-1 gradually increase, b and d gradually decrease, and the second coefficients a, b, c, d, e, f of the section angle of the section 5 at 0-0.625 change slightly; the second coefficient g of the section angle of the section 5 at 0-0.75 remains unchanged, and the second coefficient g of the section angle of the section 5 at 0.75-1 gradually increases.

Through the above design, the projected contours of the leading edge 33 and the trailing edge 34 on the meridian plane 4 and the tangent angles at different radii of the blade 3 can be adjusted to generate the shape of the blade 3, thereby optimizing the aerodynamic performance of the blade 3, improving the airflow state, reducing noise, and improving the structural strength and durability.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims (10)

1. An axial flow impeller, characterized by comprising: Fixed ring; A wheel hub, disposed in the fixing ring and coaxial with the wheel hub; A plurality of blades are arranged between the hub and the fixing ring and are spaced apart along the circumference of the hub, wherein the blades have a blade root connected to the hub, a blade top corresponding to the blade root and connected to the fixing ring, a leading edge facing the rotation direction of the impeller and located on one side of the blade root, a trailing edge away from the rotation direction of the impeller and located on the other side of the blade root, a pressure surface facing the air outlet direction and a suction surface corresponding to the pressure surface, and the blades are provided with corrugations with gradually varying amplitudes near the blade tops. 2. The axial flow impeller according to claim 1 is characterized in that the blade is concave inwardly near the blade top along the direction from the leading edge to the trailing edge to form a plurality of spaced grooves, and a single protrusion is protruded outwardly along the direction from the leading edge to the trailing edge between two adjacent grooves, and the grooves and the protrusions cooperate to form the corrugations, and the amplitude of the corrugations gradually increases along the direction from the blade root to the blade top and along the direction from the leading edge to the trailing edge. 3. The axial flow impeller according to claim 2 is characterized in that the corrugations are arranged from a preset position to a blade top, and a ratio of the distance from the preset position to the blade root to the distance from the blade root to the blade top is in the range of 0.5625-0.6785. 4. The axial flow impeller according to claim 3, characterized in that the projection profile of the leading edge on the meridian plane is a parabola, and the parabola is expressed by the following formula: y＝Ax ² +Bx Among them, y is the first coordinate of the point on the parabola on the meridian plane, x is the second coordinate of the point on the parabola on the meridian plane, and A and B are first coefficients. 5. The axial flow impeller according to claim 4 is characterized in that the leading edge and the blade root intersect to form a first intersection, the leading edge and the blade top intersect to form a second intersection, the parabola passes through the first intersection and the second intersection, the difference between the first coordinates of the first intersection and the second intersection ranges from 105 to 110, and the difference between the second coordinates of the first intersection and the second intersection ranges from 75 to 80. 6. The axial flow impeller according to claim 4 is characterized in that the projection profile of the trailing edge on the meridian plane is a straight line, the angle between the straight line and the radial surface of the hub is 0°-10°, and the end of the straight line away from the hub is toward the parabola direction. 7. The axial flow impeller according to claim 6 is characterized in that the blades are cut in the radial direction by a circle concentric with the radial surface of the hub to form a plurality of sections, the section having a midline along the direction from the leading edge to the trailing edge, a plurality of tangent points are arranged at intervals on the midline, a connecting line is formed between the tangent point and a preset point on the center axis of the hub, the angle between the connecting line and the radial surface of the hub forms a section angle, and a plurality of the section angles cooperate with each other to determine the shape of the section. 8. The axial flow impeller according to claim 7, characterized in that the cut surface angle is expressed by the following formula: y＝ax ⁶ +bx ⁵ +cx ⁴ +dx ³ +ex ² +fx+g Among them, y is the cutting angle, x is the distance from the tangent point to the intersection of the median line and the leading edge, and a, b, c, d, e, f and g are second coefficients. 9. The axial flow impeller according to claim 8 is characterized in that the second coefficients a, c, e and f gradually increase from the first preset section to the blade top, and the second coefficients b and d gradually decrease from the first preset section to the blade top, and the first preset section is the preset point. 10. The axial flow impeller according to claim 9 is characterized in that the second coefficient g remains unchanged from the blade root to the second preset section, the second coefficient g gradually increases from the second preset section to the blade top, and the ratio of the distance from the second preset section to the blade root to the distance from the blade root to the blade top is in the range of 0.7-0.8.