Double-blade opposite axial flow fan blade design method and fan

Abstract

The invention relates to the technical field of fans, and discloses a double-blade opposite axial flow fan blade design method and a fan, and the method comprises the following steps: taking the rotating axis of a hub 100 as a circle center C, and making a circular ring R0 with the same radius as the radius R0 of the hub 100 by taking the circle center C as the circle center; a point A is taken on the circular ring R0, a point An is taken outside the circular ring R0, the A and the An are connected through an arc to serve as a front bending line, and the circle center of the front bending line is located behind the front bending line in the rotating direction of the fan blades; a point A'n is taken outside the circular ring R0 and located behind the A'n in the rotating direction of the fan blade, a point A 'is taken on the circular ring R0 and located behind the A'n in the rotating direction of the fan blade, the A' and the A'n are connected through an arc to serve as a rear bending line, and the circle center of the rear bending line is located in front of the rear bending line in the rotating direction of the fan blade. The double-blade opposite axial flow fan blade with the front bent blade 200 and the rear bent blade 300 is designed, and the technical problem that the fan blade with the two-way blades cannot be designed at the same time is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of fans, and in particular, to a design method for a dual-blade relative axial-flow blade and a fan. Background Art

[0002] With the development of fan technology, traditional axial fans have certain limitations in design, especially in blade design and air flow control. Most existing fans use unidirectionally curved blades. Although this design is simple, in high-load and high-pressure environments, the air flow is blocked, which easily causes an increase in noise and energy loss.

[0003] Currently, one of the main problems faced in fan design is that the inertial force of single forward bending causes the air flow to converge centripetally, while single backward bending causes the divergence of centrifugal air flow. These effects make the air flow path longer, resulting in reduced efficiency and increased noise.

[0004] In order to improve the performance of fans, reduce noise and energy loss, the blade design urgently needs to break through the limitations of traditional design, improve the stability and efficiency of the air flow, so as to improve the performance of existing axial fans, especially in terms of air flow path, noise and energy loss.

[0005] Aiming at the above defects, the purpose of the present invention is to provide a design method for a dual-blade relative axial-flow blade and a fan, which can design a dual-blade relative axial-flow blade with both forward-bending blades 200 and backward-bending blades 300, and solve the technical problem that a blade with both bidirectional blades cannot be designed.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] A design method for a dual-blade relative axial-flow blade, comprising the following steps:

[0008] Step 1: Define the axis of rotation of the blade as the z-axis, the xy plane perpendicular to the z-axis as the design plane, the projection point of the axis of rotation of the hub 100 on the design plane as the center C, and draw a ring R0 with the same radius R0 as the hub 100 with the center C as the center in the design plane;

[0009] Take a point A on the ring R0 and a point An outside the ring R0, and connect A and An with an arc as the forward-bending curve, so that the center of the forward-bending curve is located behind the forward-bending curve along the rotation direction of the blade, where the angle ∠AOAn is denoted as the included angle φ;

[0010] Step 2: With the center C as the center and the line connecting the center C and the point An as the maximum radius Rn, make n concentric rings between R0 and Rn. The radii of the rings are R0, R1, R2, ……, Rn from the inside to the outside. The intersections of the rings and the front curved line are A, A1, A2, ……, An from the inside to the outside. The angles a, a1, a2, ……, an are formed between the lines connecting the center C and A, A1, A2, ……, An and the tangents of the front curved line at A, A1, A2, ……, An behind the rotation direction of the wind blade.

[0011] Step 3: Respectively take A, A1, A2, ……, An as the midpoints, R0, R1, R2, ……, Rn as the radii, and L, L1, L2, ……, Ln as the arc lengths to respectively determine the elementary stages 0, 1, 2, ……, n of the front-curved wind blade at the radii of R0, R1, R2, ……, Rn.

[0012] Step 4: Move the elementary stages 0, 1, 2, ……, n parallel to the positive direction of the z-axis for adjustment respectively.

[0013] Step 5: Stretch the rings where each elementary stage is located along the z-axis to form a cylindrical surface, and unfold the obtained cylindrical surface axially to get each unfolded plane. Respectively adjust the twist angles of the elementary stages 0, 1, 2, ……, n along the rotation of the unfolded plane on each unfolded plane.

[0014] Step 6: Repeat Step 4 and Step 5, proof-test the performance and give feedback for adjustment until the performance meets the requirements to determine the positions of each elementary stage. After the positions of each elementary stage are determined, use the first spline curve and the second spline curve to connect the end points at both ends of the elementary stages 0, 1, 2, ……, n respectively to obtain the overall shape of the front-curved blade 200 with the elementary stages 0, n, the first spline curve, and the second spline curve as the outer perimeter.

[0015] Step 7: Take a point A’n outside the ring R0 such that A’n is behind An in the rotation direction of the wind blade, and take a point A’ on the ring R0 such that A’ is behind A’n in the rotation direction of the wind blade. Connect A’ and A’n with an arc as the rear curved line, and make the center of the rear curved line in front of the rear curved line in the rotation direction of the wind blade, where ∠A’O’A’n is denoted as the included angle φ’, and ∠A’OA’n is denoted as the angle β.

[0016] Step 8: With the center C as the center and O’An’ as the maximum radius R’n, make n concentric rings between R’0 and R’n. The radii of the rings are R’0, R’1, R’

[0017] 2, ……, R’n from the inside to the outside. The intersections of the rings and the rear curved line are A’, A’1, A’

[0018] 2, ……, A’n, the connecting lines between the center C and A’, A’1, A’2, ……, A’n and the tangents of the front curved line at A’, A’1, A’2, ……, A’n form included angles a’, a’1, a’2, ……, a’n at the rear of the blade rotation direction;

[0019] Step 9: Respectively take A’, A’1, A’2, ……, A’n as the midpoints, R’0, R’1, R’2, ……, R’n as the radii, and L’, L’1, L’2, ……, L’n as the arc lengths to respectively determine the elementary stages 0’, elementary stage 1’, elementary stage 2’, ……, elementary stage n’ of the rear curved blade at the radii of R’0, R’1, R’2, ……, R’n;

[0020] Step 10: Parallelly move along the negative direction of the z-axis to respectively adjust the elementary stages 0’, elementary stage 1’, elementary stage 2’, ……, elementary stage n’;

[0021] Step 11: Stretch the circular rings where each elementary stage is located along the z-axis to form a cylindrical surface, axially unfold the obtained cylindrical surface to get each unfolded plane, and respectively adjust the torsion angles of the elementary stages 0’, elementary stage 1’, elementary stage 2’, ……, elementary stage n’ along the rotation of the unfolded plane in each unfolded plane;

[0022] Step 12: Repeat Step 10 and Step 11 to determine the positions of each elementary stage, and at the same time ensure that each elementary stage does not intersect with the front curved blade 200. After the positions of each elementary stage are determined, use the third spline curve and the fourth spline curve to connect the end points at both ends of the elementary stages 0’, elementary stage 1’, elementary stage 2’, ……, elementary stage n’ respectively, to obtain the overall shape of the rear curved blade 300 with the elementary stages 0’, elementary stage n’, the third spline curve and the fourth spline curve as the outer perimeter;

[0023] Step 13: Design the paired front curved blades 200 and rear curved blades 300 around the hub 100 at equal intervals along the same rotation plane to obtain a double-blade axial-flow fan blade.

[0024] Preferably, in the said Step 5 and the said Step 11, a number of equally spaced control points are arranged on each elementary stage, and the control points are used to adjust each elementary stage to form an arc in each of the unfolded planes.

[0025] Preferably, the angular ranges of the included angle φ and the included angle φ’ are 10° to 30°, and the angular range of the included angle β is 5° to 15°.

[0026] Preferably, for the front curved line, the point with the farthest distance from the line connecting point A and point An (line AAn), the foot of the perpendicular on line AAn is P, and the distance between point A and point P is 0.4 to 0.7 times the distance between point An and point P. For the rear curved line, the point with the farthest distance from the line connecting point A' and point A'n (line A'A'n), the foot of the perpendicular on line A'A'n is P', and the distance between point A' and point P' is 0.4 to 0.8 times the distance between point A'n and point P'.

[0027] Preferably, for the front curved line, the supplementary angle of the angle formed by the tangents at point A and point An is the included angle θ. For the rear curved line, the supplementary angle of the angle formed by the tangents at point A' and point A'n is the included angle θ'. The angular ranges of the included angle θ and the included angle θ' are 60° to 110°.

[0029] Preferably, in step 2, the angles of the included angles a, a1, a2, ……, an gradually decrease in sequence. In step 8, the angles of the included angles a', a'1, a'2, ……, a'n gradually increase in sequence.

[0030] Preferably, at a distance from the center C of the elementary stage less than , the angles of the included angles a, a1, a2, ……, ak gradually decrease in sequence. At a distance from the center C of the elementary stage less than , the angles of the included angles a', a'1, a'2, ……, a'k gradually increase in sequence. At a distance from the center C of the elementary stage greater than , the angles of the included angles ak+1, ak+2, ……, an gradually increase in sequence. At a distance from the center C of the elementary stage greater than , the angles of the included angles a'k+1, a'

[0031] k+2, ……, a'n gradually decrease in sequence.

[0032] Preferably, the distance from A to A' is d1, the distance from An to A'n is dn, and the maximum value of the distances between two points with the same sorting between A, A1, A2, ……, An and A', A'1, A'2, ……, A'n is dmax. Among them, the elementary stages at both ends of the distance dmax are set at distances from the center C that are respectively within the ranges of the front curved blade's and the rear curved blade's . 0.5dmax ≤ d1 ≤ 0.8dmax, 0.5dmax ≤ dn ≤ dmax.

[0033] Preferably, the front curved line and the rear curved line are composed of arcs with different radii.

[0034] A double - blade relative axial - flow fan includes a housing, a rotation driver, and blades designed by the above - mentioned design method. The rotation driver is installed in the housing, and the blades are rotatably installed at the rotation output end of the rotation driver. The rotation driver is used to drive the blades to rotate.

[0035] The technical solution provided by the present invention may include the following beneficial effects:

[0036] By adopting this design method, first design the forward - curved blade 200, and then locate and design the backward - curved blade 300 according to the position of the forward - curved blade 200. Adjust each elementary stage of the forward - curved blade 200 and the backward - curved blade 300 along the positive and negative two directions of the z - axis respectively, so that a changing gap is formed between the forward - curved blade 200 and the backward - curved blade 300, and design a double - blade relative axial - flow blade with both a forward - curved blade 200 and a backward - curved blade 300, solving the technical problem that a blade with two - way blades cannot be designed.

[0037] By designing the approximate bending line of the blade, making the bending line intersect with several concentric circles arranged at equal intervals to determine the mid - points of each elementary stage. Taking the mid - points of each elementary stage as the base points, adjust the positions of each elementary stage along the z - axis, and adjust the elementary stages of the forward - curved blade 200 and the backward - curved blade 300 along the two directions of the z - axis respectively to form a changing gap between the forward - curved blade 200 and the backward - curved blade 300. Finally, connect the endpoints of each elementary stage located on both sides of the bending line with two spline curves respectively to form the overall shape of the blade, and achieve the effect of counter - acting and canceling through the double - blade relative bending structure, achieving the required effects of reducing noise and reducing energy loss.

[0038] Adjust each elementary stage to the required radian through the control points arranged at equal intervals on each elementary stage to cooperate with the formation of the overall arc - surface shape of the blade, further enhancing the counter - acting effect of the double - blade relative axial - flow blade, reducing noise and reducing energy loss, and at the same time making the overall blade more beautiful.

[0039] Adopt the structure that the distance between the outer parts of the blades far from the hub 100 gradually becomes smaller, solving the problem of noise caused by too large rotational linear velocity and too large counter - acting on the outer side of the blades.

[0040] By forming a quasi - elliptical structure with a large middle and small ends between the forward - curved blade 200 and the backward - curved blade 300, and making the overall distance between the forward - curved blade 200 and the backward - curved blade 300 moderate, solving the problems that too small overall distance causes over - shooting and increases noise, or too large overall distance cannot form an effective canceling effect, and at the same time enhancing the overall aesthetics of the blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a design schematic diagram of an embodiment of the present invention.

[0042] Figure 2 Schematic design diagram of an embodiment of the present invention.

[0043] Figure 3 Schematic design diagram of an embodiment of the present invention.

[0044] Figure 4 Schematic design diagram of an embodiment of the present invention.

[0045] Figure 5 Schematic structural diagram of an embodiment of the present invention, with the arrow indicating the blade rotation direction.

[0046] Figure 6 Schematic structural diagram of an embodiment of the present invention, with the arrow indicating the blade rotation direction.

[0047] Figure 7 Schematic structural diagram of another embodiment of the present invention, with the arrow indicating the blade rotation direction. Detailed implementation manners

[0048] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The embodiments described by referring to the accompanying drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0049] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying 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 thus should not be construed as limiting the present invention. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features, used to distinguish and describe features, without order or importance.

[0050] In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0051] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" 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 an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0052] The embodiments of the present invention will be described below with reference to the accompanying drawings.

[0053] A design method for a pair of double - leaf axial - flow blades includes the following steps:

[0054] Step 1: Define the axis of rotation of the blade as the z - axis, and the xy - plane perpendicular to the z - axis as the design plane. The projection point of the axis of rotation of the hub 100 on the design plane is the center C. Draw a ring R0 with the same radius R0 as the hub 100 centered at C in the design plane.

[0055] Take a point A on the ring R0 and a point An outside the ring R0. Connect A and An with an arc as the front - bending line, such that the center of the front - bending line is behind the front - bending line along the rotation direction of the blade, where the angle ∠AOAn is denoted as the included angle φ.

[0056] Step 2: With the center C as the center and the line connecting the center C and the point An as the maximum radius Rn, make n concentric rings between R0 and Rn. The radii of the rings are R0, R1, R2, ……, Rn from the inside to the outside in sequence. The intersection points of the rings and the front - bending line are A, A1, A2, ……, An from the inside to the outside in sequence. The lines connecting the center C with A, A1, A2, ……, An and the tangents of the front - bending line at A, A1, A2, ……, An form included angles a, a1, a2, ……, an behind the front - bending line along the rotation direction of the blade.

[0057] Step 3: Respectively take A, A1, A2, ……, An as the mid - points, R0, R1, R2, ……, Rn as the radii, and L, L1, L2, ……, Ln as the arc lengths to respectively determine the elementary stages 0, 1, 2, ……, n of the front - bent blade at the radii of R0, R1, R2, ……, Rn.

[0058] Step 4: Parallel - move and adjust the elementary stages 0, 1, 2, ……, n along the positive direction of the z - axis respectively.

[0059] Step 5: Stretch the rings where each elementary stage is located along the z - axis to form a cylindrical surface, and axially unfold the obtained cylindrical surface to get each unfolded plane. Respectively adjust the torsion angles of the elementary stages 0, 1, 2, ……, n along the rotation of the unfolded plane in each unfolded plane.

[0060] Step 6: Repeat Step 4 and Step 5, proof-test the performance and provide feedback for adjustment until the performance meets the requirements to determine the positions of each elementary stage. After the positions of each elementary stage are determined, connect the endpoints at both ends of elementary stage 0, elementary stage 1, elementary stage 2, …, elementary stage n using the first spline curve and the second spline curve respectively to obtain the overall shape of the forward-curved blade 200 with elementary stage 0, elementary stage n, the first spline curve, and the second spline curve as the outer perimeter;

[0061] Step 7: Take a point A’n outside the ring R0 such that A’n is behind An in the rotational direction of the wind blade. Take a point A’ on the ring R0 such that A’ is behind A’n in the rotational direction of the wind blade. Connect A’ and A’n with an arc as the backward-curved line, such that the center of the backward-curved line is in front of the backward-curved line in the rotational direction of the wind blade, where the angle ∠A’O’A’n is denoted as the included angle φ’, and the angle ∠A’OA’n is denoted as the angle β;

[0062] Step 8: With the center C as the center and O’An’ as the maximum radius R’n, make n concentric rings between R’0 and R’n. The radii of the rings are R’0, R’1, R’

[0063] 2, …, R’n in sequence from the inside to the outside. The intersection points of the rings and the backward-curved line are A’, A’1, A’

[0064] 2, …, A’n in sequence from the inside to the outside. The connecting lines between the center C and A’, A’1, A’2, …, A’n and the tangents of the forward-curved line at A’, A’1, A’2, …, A’n form included angles a’, a’1, a’2, …, a’n at the rear in the rotational direction of the wind blade;

[0065] Step 9: Respectively take A’, A’1, A’2, …, A’n as the midpoints, R’0, R’1, R’2, …, R’n as the radii, and L’, L’1, L’2, …, L’n as the arc lengths to respectively determine the elementary stage 0’, elementary stage 1’, elementary stage 2’, …, elementary stage n’ of the backward-curved wind blade at radii of R’0, R’1, R’2, …, R’n;

[0066] Step 10: Translate and adjust elementary stage 0’, elementary stage 1’, elementary stage 2’, …, elementary stage n’ parallel to the negative direction of the z-axis respectively;

[0067] Step 11: Stretch the rings where each elementary stage is located along the z-axis to form a cylindrical surface, and axially unfold the obtained cylindrical surface to get each unfolded plane. Respectively adjust the torsion angles of elementary stage 0’, elementary stage 1’, elementary stage 2’, …, elementary stage n’ along the rotation of the unfolded plane in each unfolded plane;

[0068] Step 12: Repeat Step 10 and Step 11 to determine the positions of each elementary stage, while ensuring that each elementary stage does not intersect with the forward-curved blade 200. After determining the positions of each elementary stage, use the third spline curve and the fourth spline curve to connect the endpoints at both ends of the elementary stage 0’, elementary stage 1’, elementary stage 2’, …, elementary stage n’ respectively, to obtain the overall shape of the backward-curved blade 300 with the elementary stage 0’, elementary stage n’, the third spline curve and the fourth spline curve as the outer perimeter;

[0069] Step 13: Arrange the paired forward-curved blades 200 and backward-curved blades 300 equidistantly around the hub 100 along the same rotation plane to obtain a double-blade opposed axial-flow fan blade.

[0070] With this design method, first design the forward-curved blade 200, and then position and design the backward-curved blade 300 according to the position of the forward-curved blade 200. Adjust each elementary stage of the forward-curved blade 200 and the backward-curved blade 300 in the positive and negative directions of the z-axis respectively, so that a varying gap is formed between the forward-curved blade 200 and the backward-curved blade 300, and design a double-blade opposed axial-flow fan blade with both the forward-curved blade 200 and the backward-curved blade 300, solving the technical problem of being unable to design a fan blade with double-directional blades simultaneously.

[0071] As Figure 1 shown, in a specific embodiment, by designing the approximate bending line of the fan blade, making the bending line intersect with several concentric circles arranged equidistantly to determine the midpoints of each elementary stage. Taking the midpoints of each elementary stage as the base points, adjust the positions of each elementary stage along the z-axis, and adjust the elementary stages of the forward-curved blade 200 and the backward-curved blade 300 in two directions of the z-axis respectively to form a varying gap between the forward-curved blade 200 and the backward-curved blade 300. Finally, connect the endpoints on both sides of the bending line of each elementary stage with two spline curves respectively to form the overall shape of the blade, and achieve the required effect of reducing noise and energy loss through the opposed cancellation of the double-blade opposed bending structure.

[0072] Preferably, in the said Step 5 and Step 11, several equidistantly arranged control points are provided on each elementary stage, and the control points are used to adjust each elementary stage to form an arc in each of the unfolded planes.

[0073] In a specific embodiment, before adjustment, each elementary stage is a straight line in each unfolded plane. The elementary stage is adjusted to the required radian through the equidistantly arranged control points on each elementary stage to cooperate with the formation of the overall arc surface shape of the blade, further enhancing the opposed effect of the double-blade opposed axial-flow fan blade, reducing noise and energy loss, and at the same time making the overall fan blade more beautiful.

[0074] Preferably, the angular ranges of the included angle φ and the included angle φ’ are 10° to 30°, and the angular range of the included angle β is 5° to 15°.

[0075] If the angles of the included angle φ, the included angle φ', and the included angle β are too small, it will cause the wake streamline of the backward-curved blade 300 to impact the inflow of the forward-curved blade 200. If the angles are too large, it will not play the role of counteracting.

[0076] Preferably, for the forward-curved line, the point farthest from the connecting line AAn of point A and point An has its foot of perpendicular on the AAn line as P, and the distance between point A and point P is 0.4 - 0.7 times the distance between point An and point P; for the backward-curved line, the point farthest from the connecting line A'A'n of point A' and point A'n has its foot of perpendicular on the A'A'n line as P', and the distance between point A' and point P' is 0.4 - 0.8 times the distance between point A'n and point P'.

[0077] As Figure 4 shown, adopting this structure makes the most curved parts of the curved lines located in the middle positions of the forward-curved blade and the backward-curved blade along their rotational radius directions, so as to ensure that there is enough thread in the main work area of the blade to make the airflow interact and do work stably.

[0078] Preferably, the supplementary angle of the included angle formed by the tangents at point A and point An of the forward-curved line is the included angle θ, the supplementary angle of the included angle formed by the tangents at point A and point An of the backward-curved line is the included angle θ', and the angle ranges of the included angle θ and the included angle θ' are 60° - 110°.

[0080] Within this range, the degree of bending is relatively moderate, and through design, the complete cancellation of the centrifugal force and centripetal force of the wind blade can be effectively achieved. When the bending degree is too small, the length of the thread for mutual cancellation between the forward-curved blade and the backward-curved blade is not long enough, and the cancellation effect is not thorough enough. When the forward-curved degree is too large, the centrifugal force is too large, and when the backward-curved degree is too large, the centripetal force is too large. At this time, the centrifugal force or centripetal force formed by the wind blade is too large, and it is difficult to solve the problem of cancellation through design adjustment.

[0081] Preferably, in step 2, the angles of the included angles a, a1, a2,..., an gradually decrease in sequence, and in step 8, the angles of the included angles a', a'1, a'2,..., a'n gradually increase in sequence.

[0082] As Figure 2 shown, the angles of the included angles a, a1, a2,..., an are related to the overall bending shape of the forward-curved blade 200, and the angles of the included angles a', a'1, a'2,..., a'n are related to the overall bending shape of the backward-curved blade 300. Adopting this structure, the forward-curved blade 200 and the backward-curved blade 300 are relatively bent, and the distance between the outer parts of the blades away from the hub 100 gradually becomes smaller, solving the problem of noise caused by too large rotational linear velocity and too large counteracting on the outer side of the blade.

[0083] As Figure 3 、 Figure 5 、Figure 6 and Figure 7 As shown, the distance between the paired forward-curved blades 200 and backward-curved blades 300 first increases and then decreases from the direction close to the hub 100 outward along the rotational radius of the wind blades, forming a quasi-elliptical structure that is large in the middle and small at both ends.

[0084] Preferably, at a distance from the center C of the elementary stage less than , the angles of the included angles a, a1, a2, ……, ak gradually decrease in sequence. At a distance from the center C of the elementary stage less than , the angles of the included angles a’, a’1, a’2, ……, a’k gradually increase in sequence. At a distance from the center C of the elementary stage greater than , the angles of the included angles ak+1, ak+2, ……, an gradually increase in sequence. At a distance from the center C of the elementary stage greater than , the angles of the included angles a’k+1, a’

[0085] k+2, ……, a’n gradually decrease in sequence.

[0086] As Figure 2 shown, in an embodiment, the maximum rotational radii of the forward-curved blades and the backward-curved blades are the same. Starting from a radius greater than 2 / 3 of the rotational radius from the axis of rotation of the blades, the distance between the forward-curved blades 200 and the backward-curved blades 300 is relatively larger near the hub 100, and the counteracting effect weakens. By adopting a structure where the angles of the included angles ak+1, ak+2, ……, an gradually increase in sequence and the angles of the included angles a’k+1, a’k+2, ……, a’n gradually decrease in sequence at a radius greater than 2 / 3 of the rotational radius, the distance between the forward-curved blades 200 and the backward-curved blades 300 can be appropriately increased, and the formed counteracting effect can be increased.

[0087] Preferably, the sum of the angles of the included angles a and a’, a1 and a1’, a2 and a2’, ……, an and a’n is in the range of 300° to 380°.

[0088] If the sum of the corresponding angles at the same sorting positions of the forward-curved blades 200 and the backward-curved blades 300 is too small, it indicates insufficient bending degree of the blades. If the sum of the angles is too large, it indicates excessive bending degree of the blades. Both of these situations will result in poor counteracting effect of the wind blades.

[0089] Preferably, the lengths of the forward-curved blades 200 and the backward-curved blades 300 are equal.

[0090] In a specific embodiment, the rotational radii of the An point of the forward-curved blade 200 and the A’n point of the backward-curved blade 300 are the same, that is, Rn = R’n, which is convenient for counteracting design and improving the overall aesthetics of the wind blades.

[0091] Preferably, the distance from A to A' is d1, the distance from An to A'n is dn, and the maximum distance between two points with the same sorting between A, A1, A2, ……, An and A', A'1, A'2, ……, A'n is dmax. The primitive levels at both ends of the distance dmax are arranged at distances from the center of the circle C within the ranges of the forward-curved blade and the backward-curved blade, where 0.5dmax ≤ d1 ≤ 0.8dmax and 0.5dmax ≤ dn ≤ dmax.

[0092] As Figure 3 shown, in one embodiment, the maximum rotation radii of the forward-curved blade and the backward-curved blade are the same. By adopting this structure, the overall spacing between the forward-curved blade 200 and the backward-curved blade 300 is made appropriate, solving the problems of overshoot and increased noise caused by too small an overall spacing, or the inability to form an effective cancellation effect due to too large an overall spacing.

[0093] Preferably, the forward-curved line and the backward-curved line are composed of arcs with different radii.

[0094] By adopting this structure, through the combination of variable-diameter arcs, the performance and aesthetics of the adjustable fan blade can be further increased.

[0095] Preferably, fillet transition lines are provided at the intersections of the first spline curve and the second spline curve with the primitive level Rn, and fillet transition lines are provided at the intersections of the third spline curve and the fourth spline curve with the primitive level R'n;

[0096] A chamfer is added to the end of the fan blade to balance aesthetics and safety.

[0097] Preferably, the range of n is 4 to 7;

[0098] If the number of primitive levels is too small, it is difficult to adjust the fan blade to an ideal state. If the number of primitive levels is too large, the design process is too cumbersome and unnecessary.

[0099] A double-blade axial-flow fan includes a housing, a rotation driver, and a fan blade designed by the above design method. The rotation driver is installed in the housing, the fan blade is rotatably installed at the rotation output end of the rotation driver, and the rotation driver is used to drive the fan blade to rotate.

[0100] Embodiment

[0101] Table 1: Fan blade design performance requirement table.

[0102]

[0103] Note: Different models and specifications have different requirements.

[0104] Table 2: Sample fan blade performance table.

[0105]

[0106] Other configurations and operations according to the embodiments of the present invention are known to those of ordinary skill in the art and will not be described in detail herein.

[0107] In the description of this specification, the descriptions with reference to terms such as "embodiment", "example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0108] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A design method for a double-leaf relative axial flow fan blade, characterized in that The steps include: Step 1: define the axis of rotation of the fan blade as the z-axis, the xy plane perpendicular to the z-axis as the design plane, the projection point of the axis of rotation of the hub (100) on the design plane as the center C, and make a circular ring R0 with the same radius R0 as the hub (100) on the design plane with the center C as the center; Take point A on the circle R0, take point An outside the circle R0, and use an arc to connect A and An as the front bending line, so that the center of the front bending line is located behind the front bending line along the rotation direction of the wind blade, where ∠AOAn is recorded as the angle φ; Step 2: With the center C as the center of the circle and the line connecting the center C and point An as the maximum radius Rn, n concentric rings are made between R0 and Rn. The radii of the rings are R0, R1, R2, ..., Rn from the inside to the outside. The intersections of the rings with the front curved line are A, A1, A2, ..., An from the inside to the outside. The line connecting the center C and A, A1, A2, ..., An and the tangents of the front curved line at A, A1, A2, ..., An form angles a, a1, a2, ..., an behind the rotation direction of the fan blades; Step 3: Taking A, A1, A2, ..., An as midpoints, R0, R1, R2, ..., Rn as radii, and L, L1, L2, ..., Ln as arc lengths, determine the primitive level 0, primitive level 1, primitive level 2, ..., primitive level n of the forward curved blade at radii R0, R1, R2, ..., Rn, respectively; Step 4: Move parallel to the positive direction of the z-axis to adjust primitive level 0, primitive level 1, primitive level 2, ..., primitive level n respectively; Step 5: stretch the circular ring where each primitive level is located along the z-axis to form a cylindrical surface, unfold the obtained cylindrical surface along the axial direction to obtain each unfolding plane, and rotate along the unfolding plane to adjust the torsion angle of primitive level 0, primitive level 1, primitive level 2, ..., primitive level n respectively; Step 6: repeating steps 4 and 5, making samples, and repeatedly adjusting according to the test results of the torque, air volume, wind speed and noise performance of the samples until the requirements are met, so as to determine the position of each primitive level. After the position of each primitive level is determined, the endpoints of primitive level 0, primitive level 1, primitive level 2, ..., primitive level n are connected using the first spline curve and the second spline curve respectively, so as to obtain the overall shape of the forward curved blade (200) with primitive level 0, primitive level n, the first spline curve and the second spline curve as the outer periphery; Step 7: Take a point A'n outside the circle R0 so that A'n is located behind An along the direction of rotation of the wind blade, take a point A' on the circle R0 so that A' is located behind A'n along the direction of rotation of the wind blade, connect A' and A'n with an arc as a backward bending line so that the center of the backward bending line is located in front of the backward bending line along the direction of rotation of the wind blade, where ∠A'O'A'n is recorded as the angle φ', and ∠A'OA'n is recorded as the angle β; Step 8: With the center of the circle C as the center and O'An' as the maximum radius R'n, make n concentric rings between R'0 and R'n. The radii of the rings from inside to outside are R'0, R'1, R' 2. ..., R'n, the intersection points of the ring and the back bend line from inside to outside are A', A'1, A' 2, ..., A'n, the connecting line between the center C and A', A'1, A'2, ..., A'n and the tangent line of the front curved line at A', A'1, A'2, ..., A'n form angles a', a'1, a'2, ..., a'n in the rear square of the direction of rotation of the wind blade; Step 9: Taking A', A'1, A'2, ..., A'n as midpoints, R'0, R'1, R'2, ..., R'n as radii, and L', L'1, L'2, ..., L'n as arc lengths, determine the primitive level 0', primitive level 1', primitive level 2', ..., primitive level n' of the backward curved blade at radii R'0, R'1, R'2, ..., R'n respectively; Step 10: Move parallel to the negative direction of the z-axis to adjust primitive level 0', primitive level 1', primitive level 2', ..., primitive level n' respectively; Step 11: stretch the circular ring where each primitive level is located along the z-axis to form a cylindrical surface, unfold the obtained cylindrical surface along the axial direction to obtain each unfolding plane, and rotate along the unfolding plane to adjust the torsion angle of primitive level 0', primitive level 1', primitive level 2', ..., primitive level n' respectively; Step 12: Repeat steps 10 and 11 to determine the position of each primitive level, while ensuring that each primitive level does not intersect with the forward curved blade (200). After the position of each primitive level is determined, the endpoints of primitive level 0', primitive level 1', primitive level 2', ..., primitive level n' are connected using the third spline curve and the fourth spline curve respectively to obtain the overall shape of the backward curved blade (300) with primitive level 0', primitive level n', the third spline curve and the fourth spline curve as the periphery; Step 13: The paired forward curved blades (200) and backward curved blades (300) are designed to be equally spaced around the hub (100) along the same rotation plane to obtain a double-blade relative axial flow fan blade.

2. A method for designing a double-leaf relative axial flow fan blade according to claim 1, characterized in that: In step 5 and step 11, a number of equally spaced control points are arranged on each primitive level, and the control points are used to adjust each primitive level to form an arc in each of the unfolding planes.

3. A method for designing a double-blade relative axial flow fan blade according to claim 1, characterized in that: The angle φ and the angle φ' are in the range of 10° to 30°, and the angle β is in the range of 5° to 15°.

4. A method for designing a double-leaf relative axial flow fan blade according to claim 1, characterized in that: The point farthest from the front curve line and the line AAn connecting point A and point An has a foot of P at the perpendicular line AAn, and the distance between point A and point P is 0.4 to 0.7 times the distance between point An and point P. The point farthest from the rear curve line and the line A'A'n connecting point A' and point A'n has a foot of P' at the perpendicular line A'A'n, and the distance between point A' and point P' is 0.4 to 0.8 times the distance between point A'n and point P'.

5. A method for designing a double-leaf relative axial flow fan blade according to claim 1, characterized in that: The supplementary angle of the angle formed by the intersection of the tangent at point A of the front bend line and the tangent at point An is angle θ, and the supplementary angle of the angle formed by the intersection of the tangent at point A of the rear bend line and the tangent at point An is angle θ', and the angle range of angle θ and angle θ' is 60° to 110°.

6. A method for designing a double-leaf relative axial flow fan blade according to claim 1, characterized in that: The angles a, a1, a2, ..., an in step 2 gradually decrease, and the angles a', a'1, a'2, ..., a'n in step 8 gradually increase.

7. A method for designing a double-leaf relative axial flow fan blade according to claim 1, characterized in that: At the primitive level, the distance from the center C is less than At this point, the angles a, a1, a2, ..., ak gradually decrease in sequence, and the distance from the center C at the primitive level is less than At the point, the angles a', a'1, a'2, ..., a'k gradually increase in sequence, and the distance from the center C at the primitive level is greater than At the point, the angles ak+1, ak+2, ..., an gradually increase in sequence, and the distance from the center C at the primitive level is greater than At this point, the angles a'k+1, a'k+2, ..., a'n gradually decrease in sequence.

8. The method for designing a dual-blade relative axial flow fan blade according to claim 1, characterized in that: The distance from A to A' is d1, the distance from An to A'n is dn, and the maximum distance between two points of the same order from A, A1, A2, ..., An to A', A'1, A'2, ..., A'n is dmax, where the primitive levels at both ends of the distance dmax are set at a distance from the center C of the front curved blade. and backward curved blades Within the range, 0.5dmax≤d1≤0.8dmax, 0.5dmax≤dn≤dmax.

9. A method for designing a dual-blade relative axial flow fan blade according to claim 1, characterized in that: The front curved line and the rear curved line are composed of multiple arcs with different radii.

10. A two-blade opposed axial flow fan, characterized in that: It comprises a housing, a rotating driver and a fan blade designed using the design method described in any one of claims 1 to 9, wherein the rotating driver is mounted on the housing, the fan blade is rotatably mounted on the rotating output end of the rotating driver, and the rotating driver is used to drive the fan blade to rotate.

Images