CN110939603A - Blade and axial flow impeller using same - Google Patents

Abstract

A blade comprising a blade tip, a blade root, a leading edge and a trailing edge, wherein the leading edge and the trailing edge each extend from the blade tip to the blade root; the blade being rotatable about a rotation axis which intersects a plane normal to the rotation axis at a perpendicular foot; a projection of the leading edge on the normal plane along the axis of rotation is a first curve having an even number of inflection points. The blade of this application can reduce the noise when the blade rotates to promote aerodynamic performance.

Description

Blade and axial flow impeller using same

Technical Field

The application relates to the field of rotating machinery such as fans, pumps, compressors and the like, in particular to a blade and an axial flow impeller using the same.

Background

The front edge and the tail edge of the traditional blade are generally monotonous and smooth curves, and the aerodynamic performance of the blade is low and the noise is high because the flow separation on the surface of the blade is serious and a vortex is formed.

Disclosure of Invention

Exemplary embodiments of the present application may address at least some of the above-mentioned issues.

According to a first aspect of the present application, there is provided a blade comprising a blade tip, a blade root, a leading edge and a trailing edge, wherein the leading edge and the trailing edge each extend from the blade tip to the blade root; the blade being rotatable about a rotation axis which intersects a plane normal to the rotation axis at a perpendicular foot; a projection of the leading edge on the normal plane along the axis of rotation is a first curve having an even number of inflection points.

The blade according to the first aspect, wherein the number of inflection points is 2, 4 or 6.

According to the blade of the first aspect, the number of the inflection points is selected to reduce the formation of the vortex.

According to the blade of the first aspect, a connecting line between any point on the first curve and the drop foot is a first connecting line; the intersection point of the blade root and the leading edge is a second connecting line with the connecting line of the foot along the projection point of the rotating axis on the normal plane; an included angle between the first connecting line and the second connecting line is called a wrap angle theta; the wrap angle theta of any point on the first curve satisfies theta epsilon [0 DEG, 40 DEG ].

The blade according to the first aspect, wherein the trailing edge has a plurality of slots.

According to the blade of the first aspect, the projection of the trailing edge on the normal plane along the rotation axis is a second curve, wherein the included angle between the groove walls of each groove is α, the groove depth is H, the length of the second curve is L, the included angle and the groove depth satisfy α ∈ [10 °,100 ° ], H ═ KxL, K ∈ [ 1.5%, 20%, and the projection point of the intersection point of the tip and the trailing edge on the normal plane along the rotation axis is located on the groove wall.

According to the blade of the first aspect, the plurality of slots are equally spaced.

According to the blade of the first aspect described above, the plurality of grooves have the same opening width, and the groove depths increase in an equal difference.

The blade according to the first aspect, wherein a bottom of each of the plurality of grooves has a circular arc shape.

According to a second aspect of the present application, there is provided an axial flow impeller comprising a hub having an axis of rotation about which the hub is rotatable; and at least two blades disposed on the outer circumferential surface of the hub, and each of the at least two blades including a blade tip, a blade root, a leading edge, and a trailing edge, wherein the leading edge and the trailing edge extend from the blade tip to the blade root, respectively; the blade being rotatable about a rotation axis which intersects a plane normal to the rotation axis at a perpendicular foot; a projection of the leading edge on the normal plane along the axis of rotation is a first curve having an even number of inflection points.

According to a third aspect of the present application, there is provided a blade comprising a blade tip, a blade root, a leading edge and a trailing edge, wherein the leading edge and the trailing edge each extend from the blade tip to the blade root; the trailing edge of the blade has a plurality of slots.

According to the blade of the third aspect, the blade can rotate around a rotation axis, the rotation axis is perpendicularly intersected with a normal plane of the rotation axis to a foot, the projection of the tail edge along the rotation axis on the normal plane is a second curve, the included angle between the groove walls of each groove is α, the groove depth is H, the length of the second curve is L, the included angle and the groove depth meet the requirements of α epsilon [10 degrees and 100 degrees ], H is K multiplied by L, K epsilon [1.5 percent and 20 percent, and the projection point of the intersection point of the blade tip and the tail edge along the rotation axis on the normal plane is located on the groove walls.

According to the blade of the third aspect, the plurality of slots are equally spaced.

According to the blade of the above third aspect, the opening widths of the plurality of grooves are the same, and the groove depths are increased in an equal difference.

According to the vane of the third aspect, the bottom of each of the plurality of grooves has a circular arc shape.

According to a fourth aspect of the present application, there is provided an axial flow impeller comprising a hub having an axis of rotation about which the hub is rotatable; and at least two blades disposed on the outer circumferential surface of the hub, and each of the at least two blades including a blade tip, a blade root, a leading edge, and a trailing edge, wherein the leading edge and the trailing edge extend from the blade tip to the blade root, respectively; the trailing edge of the blade has a plurality of slots.

The blade of this application can improve the blade performance, reduces the running noise.

Drawings

The features and advantages of the present application may be better understood by reading the following detailed description with reference to the drawings, in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 illustrates a perspective view of an impeller using blades of an embodiment of the present application;

FIG. 2 shows a perspective view of a blade used in the impeller of FIG. 1;

FIG. 3A shows a projection of the blade of FIG. 1 in the direction of the axis of rotation X in a normal plane;

FIG. 3B illustrates a projection of a blade of another embodiment of the present application in a plane normal to the axis of rotation X;

FIG. 3C illustrates a projection of a blade of yet another embodiment of the present application in a plane normal to the axis of rotation X;

FIGS. 4A-4B show a vorticity distribution contrast plot and a top surface streamline contrast plot, respectively, for a conventional blade versus a blade of the present application;

FIG. 5 shows a projection of the blade in the direction of the axis of rotation X in a normal plane;

FIG. 6A shows an enlarged projection of the slot shown in FIG. 3A in the normal plane in the direction of the axis of rotation X;

FIG. 6B shows an enlarged projection of another embodiment of the slot of the present application in the normal plane in the direction of the axis of rotation X;

FIG. 7 shows a partial enlarged view of FIG. 3A;

FIG. 8 illustrates a static pressure and overall efficiency comparison of the blade 112 of the present application with a conventional blade;

FIG. 9 shows a noise contrast plot for blade 112 of the present application versus a conventional blade.

Detailed Description

Various embodiments of the present application will now be described with reference to the accompanying drawings, which form a part hereof. In the following drawings, like parts are given like reference numerals and similar parts are given like reference numerals to avoid repetition of the description.

Fig. 1 is a perspective view of an impeller 100 using blades of an embodiment of the present application. As shown in fig. 1, impeller 100 includes a hub 110 and three blades 112. Hub 110 has an axis of rotation X, and a cross-section of hub 110 perpendicular to axis of rotation X is circular. Three blades 112 are uniformly arranged on the outer circumferential surface of the hub 110, and are integrally connected with the blades 112. Hub 110 and blades 112 are rotatable together about an axis of rotation X. As an example, the impeller 100 of the present application rotates about the rotation axis X in a clockwise direction (i.e., a rotation direction indicated by an arrow in fig. 1). Those skilled in the art will appreciate that hub 110 may have other shapes and that the number of blades 112 may be at least two. Hub 110 may be shaped to match the number of blades 112. For example, when the number of blades 112 is three, hub 110 has a triangular cross-section perpendicular to axis of rotation X; when the number of blades 112 is four, a cross section of hub 110 perpendicular to rotation axis X is a quadrangle.

Fig. 2 is a perspective view of a blade 112 used in the impeller 100 of fig. 1. As shown in FIG. 2, blade 112 includes an upper surface, a lower surface, a blade tip 216, a blade root 218, a leading edge 222, and a trailing edge 220. Where "leading edge 222" represents the leading edge in the direction of blade rotation. "trailing edge 220" represents the trailing edge in the direction of blade rotation. "root 218" means the edge of the blade that intersects the hub. "blade tip 216" represents another edge opposite the blade root. The upper and lower surfaces each extend from the blade tip 216 to the blade root 218, and also each extend from the leading edge 222 to the trailing edge 220. The trailing edge 220 of the blade 112 of the present application has a plurality of slots 232, each of the plurality of slots 232 extending toward the leading edge 222.

The impeller 100 has a normal plane (not shown) disposed perpendicular to the rotation axis X, and the intersection of the rotation axis X and the normal plane is a drop foot O (see fig. 3A-3C). As will be appreciated by those skilled in the art, the normal plane is a virtual plane for better illustrating the specific configuration of the leading edge 222 and the trailing edge 220 of the blade 112. The projection of the leading edge 222 of the blade 112 of the present application onto the normal plane in the direction of the axis of rotation X is a first curve, wherein the first curve has an even number of inflection points. The inflection point is a dividing point of the concave arc and the convex arc.

FIG. 3A is a projection of blade 112 of FIG. 1 in a plane normal to the axis of rotation X. As shown in fig. 3A, the first curve has two inflection points, an inflection point a and an inflection point b. The projected point of the intersection of the blade root 218 and the leading edge 222 on the normal plane in the direction of the rotation axis X is point a, and the projected point of the intersection of the blade tip 216 and the leading edge 222 on the normal plane in the direction of the rotation axis X is point B. The curve from point a to inflection point a and the curve from inflection point B to point B are concave arcs; the curve from inflection point a to inflection point b is a convex arc. The point P is any point on the first curve, and the line connecting the point P and the foot O is the first line. The line connecting the point A and the drop foot O is a second line. The included angle between the first connecting line and the second connecting line is a wrap angle theta. In the embodiment of the present application, the wrap angle θ of any point P on the first curve satisfies θ e [0 °,40 ° ], and the line connecting any point P on the first curve and the drop foot O is on the same side of the first line.

FIG. 3B is a projection of a blade of another embodiment of the present application in a plane normal to the axis of rotation X. As shown in fig. 3B, the first curve has four inflection points, i.e., an inflection point a, an inflection point B, an inflection point c, and an inflection point d. A curve from the point a to the inflection point a, a curve from the inflection point B to the point c, and a curve from the inflection point d to the point B are concave arcs; the curve from inflection point a to inflection point b and the curve from inflection point c to inflection point d are convex arcs.

FIG. 3C is a projection of a blade of yet another embodiment of the present application in the plane normal to the axis of rotation X. As shown in fig. 3C, the first curve has six inflection points, i.e., an inflection point a, an inflection point b, an inflection point C, an inflection point d, an inflection point e, and an inflection point f. A curve from a point a to an inflection point a, a curve from an inflection point B to a point inflection point c, a curve from an inflection point d to a point inflection point e, and a curve from an inflection point f to a point B are concave arcs; the curve from inflection point a to inflection point b, the curve from inflection point c to inflection point d, and the curve from inflection point e to inflection point f are convex arcs.

The wrap angle theta of any point on the first curve in fig. 3B and 3C also satisfies theta e [0 deg., 40 deg. ], and the connecting line of any point P on the first curve and the drop foot O is on the same side of the first connecting line.

Note that the first curve in the present application indicates a projection of the leading edge 222 on the normal plane in the direction of the rotation axis X, and does not indicate that a curve having a specific shape is the first curve.

Fig. 4A and 4B are respectively a vorticity distribution contrast diagram and a blade upper surface streamline contrast diagram of a normal blade (a blade in which a curve of a projection of a leading edge on a normal plane in the rotation axis X direction does not have an inflection point, that is, a curve of a projection of a leading edge on a normal plane in the rotation axis X direction is a monotonous smooth curve) and the blade 112 of the present application. In fig. 4A and 4B, the left blade is a normal blade, and the right blade is the blade 112 of the present application. Leading edge 222 in the present application reduces loading of leading edge 222 of blade 112 by providing concave and convex arcs to increase the working length of leading edge 222. As the blades 112 rotate, the concave and convex arcs on the leading edge 222 can force larger stripping vortices that would otherwise collect on the upper surface of the blades 112 near the leading edge 222 to break up into at least two smaller vortices (as shown in fig. 4A), thereby reducing turbulence intensity and dissipation losses due to turbulence, improving aerodynamic performance while reducing noise. The splitting into smaller vortices also prevents the blade from tearing at high speed rotation due to the presence of larger peeling vortices, thereby increasing the reliability of the blade in operation. Further, the separation vortices that have been split into smaller ones by the concave arcs and convex arcs on the leading edge 222 are less likely to move relative to each other in the radial direction of the blade 112 and cause secondary flows when propagating toward the trailing edge 220, and the relative velocity streamlines of the air on the surface of the blade 112 intersect as little as possible (as shown in fig. 4B), thereby achieving an improvement in aerodynamic performance and a reduction in noise.

FIG. 5 is a projection of blade 112 in the normal plane in the direction of axis of rotation X to illustrate several distribution points Q of slots 232. As shown in FIG. 5, the trailing edge 220 has a contour 502. The trailing edge 220 has a plurality of slots 232, each having a distribution point Q, each slot having a distribution point Q located on the contour 502. As an example, the distribution points Q of the slots 232 are equally spaced.

Fig. 6A is an enlarged projection view of the groove 232 shown in fig. 3A on a normal plane in the rotation axis X direction to show a specific structure of the groove 232. As shown in fig. 6A, the projection of the trailing edge 220 onto the normal plane along the direction of the rotation axis X is a second curve, and the length of the second curve is L. As an example, a straight line perpendicular to the contour line 502 is drawn at the distribution point Q, and the position of the bottom point G is determined in accordance with the groove depth H. Wherein, the groove depth H satisfies:

H＝K×L，K∈[1.5％,20％。

the groove wall line NG and the groove wall line MG form an included angle α, and the included angle α satisfies:

α∈[10°,100°]。

MN is the opening width of slot 232. The groove bottom EF is arc-shaped and has a radius r. The groove base EF is tangent to the groove wall NG and the groove wall MG at point E and point F, respectively. Radius r satisfies

Further, the first connection portion ST of the slot wall line NG and the contour line 502 and the second connection portion IJ of the slot wall line MG and the contour line 502 are also circular arc-shaped with a radius R. The first connection ST is tangent to the cell wall line NG and the contour line 502 at points S and T, respectively; the second junction IJ is tangent to the groove wall line MG and the contour line 502 at points I and J, respectively. Radius R satisfies

The first connection portion ST, the groove wall SE, the groove bottom EF, the groove wall FI, and the second connection portion IJ form the groove 232. Point C is the projected point of the intersection of the blade tip 216 and the trailing edge 220 on the normal plane in the direction of the rotation axis X, and the projected point C is located on the slot wall FI.

Those skilled in the art will appreciate that the groove 232 may not have the first connection portion ST or the second connection portion IJ, and the radius R of the first connection portion ST or the second connection portion IJ may not be the same.

As another example, the straight line QG may not be perpendicular to the contour line 502, but may be oriented toward the blade tip 216, blade root 218, or leading edge 222.

FIG. 6B is an enlarged projection view of another embodiment of the slot 232 of the present application in the normal plane in the direction of the axis of rotation X. The embodiment shown in fig. 6B differs from the embodiment shown in fig. 6A in that the groove 232 does not have the first connection ST, the groove bottom EF, and the second connection IJ. The groove wall NG and the groove wall MG form the groove 232. The point C is a projection point of an intersection point of the blade tip 216 and the trailing edge 220 on a normal plane in the direction of the rotation axis X, and the projection point C is located on the groove wall MG.

FIG. 7 is a close-up view of FIG. 3A to show the configuration at the intersection of the blade tip 216 and trailing edge 220, as shown in FIG. 7, the slot wall 704 of slot 232 closest to blade tip 216 forms a tip 702 with blade tip 216, and the included angle between blade tip 216 and slot wall 704 is β to satisfy β E [5, 80 ].

It will be appreciated by those skilled in the art that the plurality of slots 232 at the trailing edge 220 have the same opening width MN. The groove depth H increases in an equal difference in the direction from the root 218 to the tip 216.

Referring to fig. 4A and 4B, fig. 4A and 4B are respectively a vorticity distribution comparison diagram of a normal blade (a blade having no groove at a trailing edge, i.e., a curve of a projection of the trailing edge on a normal plane in the direction of the rotation axis X is a monotone smooth curve) and the blade 112 of the present application, and a blade upper surface streamline comparison diagram. As shown in FIG. 4A, as blades 112 rotate, the peeling vortex develops chaotic turbulence at trailing edge 220, which can interact with grooves 232 on trailing edge 220 to reduce noise dispersion. The slots 232 in the trailing edge 220 are effective in reducing low frequency noise due to its longer travel distance in the atmosphere. In addition, the groove 232 on the trailing edge 220 also splits larger stripping vortices on the upper surface of the blade 112 near the trailing edge 220 into smaller sized stripping vortices to avoid the larger stripping vortices from affecting the inlet airflow at the leading edge 222 of the next blade 112 immediately downstream, thereby avoiding degradation of aerodynamic performance due to poor inlet conditions. As shown in FIG. 4B, slots 232 in trailing edge 220 also reduce secondary flows caused by radial cross-talk of the upper surfaces of blades 112, thereby reducing dissipation losses.

FIG. 8 is a graph comparing static pressure and overall efficiency of blades 112 of the present application with conventional blades. In fig. 8, the broken line represents the air volume-total efficiency relationship, and the solid line represents the air volume-static pressure relationship. As can be seen from fig. 8, the total efficiency of the blade in the present application is higher than that of the general blade at the same air volume. Specifically, the air volume is 19000m³/h-25000m³The total efficiency of the blade of the present application is about 8% higher than that of the conventional blade at/h. In addition, under the same air volume, the static pressure of the blade in the application is higher than that of the common blade. Specifically, the air volume is 15000m³/h-20000m³The static pressure of the vanes of this application is about 20Pa higher than that of the conventional vanes at/h. It can be seen that the aerodynamic performance (i.e. static pressure and overall efficiency) of the blade of the present application is superior to that of a conventional blade.

FIG. 9 is a graph comparing noise of blade 112 of the present application with a conventional blade. As can be seen from FIG. 9, at frequencies of 1000Hz-10000Hz, the noise emitted during normal blade operation is about 5dB higher than the noise emitted during blade operation of the present application. And in addition, when the frequency of the noise is 0Hz-1000Hz, the noise generated when the blade runs is lower than that generated when the common blade runs. It can be seen that the blade of the present application emits substantially less noise over the full frequency band than conventional blades.

It should be noted that the blade 112 may have a variety of blade profiles from leading edge to trailing edge, and may be a constant thickness profile or any two-dimensional airfoil profile.

While only certain features of the application have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the application.

Claims (16)

1. A blade (112) comprising: Tip (216), root (218), leading edge (222), and trailing edge (220), wherein the leading edge (222) and the trailing edge (220), respectively, extend from the tip (216) to the blade root (218); the blade (112) can rotate around a rotation axis (x), and the rotation axis (x) intersects perpendicularly with a normal plane of the rotation axis (x) at the foot of the (O); It is characterized by: The projection of the leading edge (222) on the normal plane along the rotation axis (x) direction is a first curve, and the first curve has an even number of inflection points. 2. The blade (112) of claim 1, wherein: The number of the inflection points is 2, 4 or 6. 3. The blade (112) of claim 1, wherein: The selection of the number of inflection points can reduce the formation of eddy currents. 4. The blade (112) according to claim 3, characterized in that: the connection line between any point on the first curve and the vertical foot (O) is the first connection line; The line connecting the projection point (A) of the blade root (218) and the leading edge (222) on the normal plane along the direction of the rotation axis (x) and the vertical foot (O) for the second connection; The included angle between the first connection line and the second connection line is called the wrap angle θ; The wrap angle θ of any point on the first curve satisfies θ∈[0°, 40°]. 5. The blade (112) of claim 1, wherein: The trailing edge (220) has a number of grooves (232). 6. The blade (112) of claim 5, wherein: The projection of the trailing edge (220) along the rotation axis (x) direction on the normal plane is a second curve, wherein the included angle between the groove walls of each groove is α, and the groove depth is H, The length of the second curve is L; The included angle and the groove depth satisfy: α∈[10°, 100°]; H=K×L, K∈[1.5%, 20%]; and The projection point (C) of the intersection point of the blade tip (216) and the trailing edge (220) along the rotation axis (x) direction on the normal plane is located on the groove wall. 7. The blade (112) of claim 5, wherein: The distances between the plurality of grooves (232) are the same. 8. The blade (112) of claim 6, wherein: The opening widths of the plurality of grooves (232) are the same, and the depths of the grooves are equidistantly increasing. 9. The blade (112) of claim 5, wherein: The bottom of each of the plurality of grooves (232) is arc-shaped. 10. An axial flow impeller (100), characterized in that it comprises: a hub (110) having an axis of rotation (x) about which the hub (110) is rotatable; and At least two blades (112) according to any one of claims 1-9, the at least two blades (112) being arranged on the outer circumferential surface of the hub (110). 11. A blade (112) comprising: Tip (216), root (218), leading edge (222), and trailing edge (220), wherein the leading edge (222) and the trailing edge (220), respectively, extend from the tip (216) to said leaf root (218); It is characterized by: The trailing edge (220) of the blade (112) has a number of slots (232). 12. The blade (112) of claim 11, wherein: The blade (112) can rotate around a rotation axis (x), and the rotation axis (x) intersects perpendicularly with a normal plane of the rotation axis (x) at the vertical foot (O); The projection of the trailing edge (220) along the rotation axis (x) direction on the normal plane is a second curve, wherein the included angle between the groove walls of each groove is α, and the groove depth is H, The length of the second curve is L; The included angle and the groove depth satisfy: α∈[10°, 100°]; H=K×L, K∈[1.5%, 20%]; and The projection point (c) of the intersection of the blade tip (216) and the trailing edge (220) along the rotation axis (x) direction on the normal plane is located on the groove wall. 13. The blade (112) of claim 11, wherein: The distances between the plurality of grooves (232) are the same. 14. The blade (112) of claim 12, wherein: The opening widths of the plurality of grooves (232) are the same, and the depths of the grooves increase equally. 15. The blade (112) of claim 11, wherein: The bottom of each of the plurality of grooves (232) is arc-shaped. 16. An axial flow impeller (100), characterized in that: the axial flow impeller (100) comprises: a hub (110) having an axis of rotation (x) about which the hub (110) is rotatable; and At least two blades (112) according to any one of claims 11-15, the at least two blades (112) being arranged on the outer circumferential surface of the hub (110).

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