Backward plate type three-dimensional flow blade volute-free centrifugal fan

Abstract

A backward plate type three-dimensional flow blade volute-free centrifugal fan comprises a rear wheel disc, a blade and a front wheel disc which are coaxially connected, the surface of the blade belongs to a spatial three-dimensional curved surface, the blade comprises a rear blade root, a front blade root, an inlet edge, an outlet edge, a pressure surface and a suction surface, and a plurality of sections are taken between the middle of the rear blade root and the middle of the front blade root in the Z-axis direction. The cross sections are the cross sections which are obliquely divided in the direction where the blades are attached to the back face of the rear wheel disc, a rear blade root and a front blade root are captured by the two cross sections located at the ends respectively, and the inlet angle and the outlet angle of each cross section are optimally designed respectively. According to the design of the blade flow channels, the pneumatic loss and the noise level can be reduced to the maximum extent, it is guaranteed that air flow reaches the optimal state under the rated working condition, and the static pressure efficiency of the impeller is improved to an almost unprecedented height; meanwhile, the plate type blade fan has the advantages of being low in machining and manufacturing difficulty, low in machining cost, high in working efficiency and the like.

Description

Technical Field

[0001] The present application relates to the field of fan technology and its application technology, and in particular to a backward plate-type three-dimensional flow blade centrifugal fan without volute. Background Art

[0002] The backward type voluteless centrifugal fan is a general-purpose fan that is increasingly preferred and widely used. It is being widely used in various industrial and civil fields, such as EMU cooling units, HVAC units, fresh air units, air supply systems, etc. Compared with traditional volute fans, voluteless fans have many advantages such as simple structure, easy layout, convenient installation and maintenance.

[0003] In the prior art, the backward-facing centrifugal fan without volute is mainly composed of an impeller, an air inlet and a motor. The impeller is the core component of the fan, which generates airflow by rotating. The air inlet is used to guide the direction of the airflow, and the motor provides power for the fan. The general centrifugal fan without volute adopts a plate-type single arc blade design. Since the blade cross-section is a single arc shape, it has the characteristics of easy processing and manufacturing. However, the blade shape of the plate-type blade does not conform to the flow characteristics of the complex airflow inside the impeller, resulting in airflow loss and increased aerodynamic noise, and the efficiency of the fan decreases. In order to improve efficiency and reduce noise, some centrifugal fans without volute adopt a two-dimensional or even three-dimensional blade airfoil design, that is, the cross-section of the blade is an airfoil design. By adjusting the shape and angle of the airfoil, the airflow in the impeller can be affected, and higher efficiency can be achieved. However, the impeller with an airfoil cross-section will inevitably increase the difficulty of manufacturing and increase the production cost.

[0004] Therefore, there is an urgent need for a new type of volute-free centrifugal fan that is easy to manufacture, has low processing cost and high working efficiency. Summary of the invention

[0005] The purpose of the present application is to provide a backward plate-type three-dimensional flow blade centrifugal fan without volute, so as to solve the problems existing in the prior art such as high difficulty in manufacturing, high processing cost, low working efficiency, etc.

[0006] The embodiments of the present application can be implemented through the following technical solutions:

[0007] A backward plate-type three-dimensional flow blade centrifugal fan without volute, comprising a rear wheel disc, blades, and a front wheel disc, wherein the blades are connected between the back side of the rear wheel disc and the front wheel disc arranged coaxially, and the surface of the blades is a three-dimensional curved surface in space, wherein the blades comprise a rear blade root, a front blade root, an inlet edge, an outlet edge, a pressure surface, and a suction surface, wherein the rear blade root is a curved surface connecting the blade with the back side of the rear wheel disc, and the front blade root is a curved surface connecting the blade with the back side of the front wheel disc;

[0008] Along the inlet and outlet direction of the Z axis, several cross sections are taken between the middle of the rear blade root and the middle of the front blade root, wherein the cross sections are cross sections of the blade divided obliquely along the direction where the blade is attached to the back of the rear wheel disc, wherein the two cross sections located at the end portions capture the rear blade root and the front blade root respectively;

[0009] In each section, the contour line of the pressure surface is the cross-sectional profile, and the angle between the two tangent lines at the end point where the inlet edge of the cross-sectional profile is located is recorded as the inlet angle α, and the angle between the two tangent lines at the end point where the outlet edge of the cross-sectional profile is located is recorded as the outlet angle β;

[0010] Along the front-to-rear direction from the front wheel disc to the rear wheel disc, the inlet angle α of the section adjacent to the front wheel disc is greater than the inlet angle α of the section adjacent to the rear wheel disc, and the inlet angle α of the section adjacent to the rear wheel disc is greater than the inlet angle α of the section located in front of it; the outlet angle β of the section adjacent to the front wheel disc is greater than the outlet angle β of the section located behind it, and the outlet angle β of the section adjacent to the rear wheel disc is greater than the outlet angle β of the section located in front of it.

[0011] Furthermore, the inlet angle α and outlet angle β of each section are respectively made in the following manner:

[0012] On the pressure surface, the endpoint where the cross section intersects the inlet edge is recorded as point N, the endpoint where the cross section intersects the outlet edge is recorded as point M, the intersection line of the cross section and the pressure surface is curve NM, recorded as the cross section profile, and two tangents are drawn at point N and point M respectively, and are recorded as tangent A and tangent D respectively;

[0013] A straight line is then drawn perpendicular to the back side of the rear wheel disc, intersecting the Z axis line, and the intersection point is located at the center of the center hole end of the rear wheel disc. The straight line is recorded as the E section line. Two perpendicular lines are drawn from points N and M in the cross section respectively, and the intersection point of the two perpendicular lines at the E section line is O. In the plane where NMO is located, a front circle is drawn with the straight line NO as the leading edge radius, and the tangent of the front circle at N is recorded as the B tangent. Similarly, in the plane where NMO is located, a rear circle is drawn with the straight line MO as the trailing edge radius, and the tangent of the rear circle at M is recorded as the C tangent. The inlet angle is ∠BNA, and the outlet angle is ∠DMC.

[0014] Furthermore, along the Z-axis direction, at least five spaced-apart sections are taken between the middle of the rear blade root and the middle of the front blade root, and each section is a first section, a second section, a third section, a fourth section, and a fifth section, and the inlet angle α of each section is α1, α2, α3, α4, and α5, respectively, wherein α5>α1>α2>α3>α4, and the outlet angle β of each section is β1, β2, β3, β4, and β5, respectively, wherein β5>β4, and β1>β2>β3>β4.

[0015] Furthermore, the inlet angle α1 of the first section is in the range of 7.6°-15.6°, the inlet angle α2 of the second section is in the range of 4.6°-12.6°, and the inlet angle α5 of the fifth section is in the range of 12.9°-20.9°.

[0016] Furthermore, the inlet angle α3 of the third section has a value range of 3.2°-11.2°, and the inlet angle α4 of the fourth section has a value range of 1.7°-9.7°.

[0017] Furthermore, the outlet angle β1 of the first cross section has a value range of 39.3°-43.3°, and the outlet angle β2 of the second cross section has a value range of 32.5°-36.5°.

[0018] Furthermore, the outlet angle β4 of the fourth section has a value range of 29.1°-33.1°, and the outlet angle β5 of the fifth section has a value range of 30.6°-34.6°.

[0019] Furthermore, the outlet angle β3 of the third section has a value range of 29.7°-33.7°.

[0020] Furthermore, a vertical extension line is drawn at point O in any section along the Z-axis direction, and the intersection of the vertical extension line and the section profile is H, and ∠HON is recorded as the position angle γ, wherein the position angle γ3 of the third section is greater than the position angle γ2 of the second section Q2, and the position angle γ3 of the third section is greater than the position angle γ4 of the fourth section, so that part of the leading edge of the inlet edge is convex.

[0021] Furthermore, the trailing edge of the outlet edge is concave, and the chord lengths C of the various cross sections are different.

[0022] Furthermore, the outlet edge at the location of the second section is set to be concave, that is, the chord length d of the second section is c2 Less than the chord length d of the first section c1 , and the chord length of the second section d c2 is smaller than the chord length d of the third section c3 .

[0023] The backward plate-type three-dimensional flow blade volute-free centrifugal fan provided by the embodiment of the present application has at least the following beneficial effects:

[0024] The blades in this application are structurally improved through analysis of the internal flow field of the fan impeller. By selecting appropriate blade inlet and outlet angles and chord length dimensions for multiple sections of the blade, each section of the blade achieves optimal aerodynamic performance. The concave design of the blade trailing edge makes the flow field on the blade pressure surface more uniform, and the impeller efficiency is further improved. Especially in the actual measurement of type A intake performance, the measured impeller efficiency can reach up to 82.2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of a backward plate-type three-dimensional flow blade centrifugal fan without volute in this application;

[0026] Figure 2 A side view of the rear wheel disc in this application;

[0027] Figure 3 A side view of the front blade disk in this application;

[0028] Figure 4 It is a schematic diagram of the three-dimensional structure of the blade in this application;

[0029] Figure 5 This is a schematic diagram of the position and size of the cross section of the blade in this application;

[0030] Figure 6 It is a first cross-sectional schematic diagram of a blade in this application;

[0031] Figure 7 is a second cross-sectional schematic diagram of a blade in the present application;

[0032] Figure 8 is a third cross-sectional schematic diagram of the blade in this application;

[0033] Fig. 9 is a fourth cross-sectional schematic diagram of a blade in the present application;

[0034] Fig.10 is a fifth cross-sectional schematic diagram of a blade in the present application;

[0035] Fig.11 This is the pressure cloud diagram of the trailing edge of the centrifugal fan blade in the outlet area under different shapes;

[0036] Fig.12 It is the velocity cloud diagram of the rotating surface of the centrifugal fan at the impeller inlet;

[0037] Fig.13 It is a comparison curve diagram of the measured data of static pressure in each case;

[0038] Fig.14 The following is a comparison graph of the measured data of the static pressure efficiency of each case.

[0039] Numbers in the figure

[0040] 1-rear wheel disc; 11-outer edge of rear wheel disc; 12-center hole end; 13-transition surface; 2-blade; 21-rear blade root; 22-front blade root; 23-inlet edge 23; 24-outlet edge 24; 25-pressure surface 25; 26-suction surface; 3-front wheel disc; 31-outer edge of front wheel disc; 32-inlet end of front wheel disc;

[0041] Q1-first section; Q2-second section; Q3-third section; Q4-fourth section; Q5-fifth section. DETAILED DESCRIPTION

[0042] Hereinafter, the present application will be further described based on preferred embodiments with reference to the accompanying drawings.

[0043] In addition, various components on the drawings are enlarged (thickened) or reduced (thinned) for ease of understanding, but this practice is not intended to limit the scope of protection of the present application.

[0044] Words importing the singular also include the plural and vice versa.

[0045] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the products of the embodiments of the present application are usually placed when in use, it is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply 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 a limitation on the present application. In addition, in the description of the present application, in order to distinguish different units, the words first, second, etc. are used in this specification, but these are not limited by the order of manufacture, nor can they be understood as indicating or implying relative importance, and their names may be different in the detailed description and claims of the present application.

[0046] The vocabulary in this specification is used to illustrate the embodiments of the present application, but is not intended to limit the present application. It should also be noted that, unless otherwise clearly specified and limited, the terms "disposed", "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, a direct connection, an indirect connection through an intermediate medium, or a connection between the two elements. For those skilled in the art, the specific meanings of the above terms in this application can be specifically understood.

[0047] like Figures 1 to 4As shown, a backward plate-type three-dimensional flow blade centrifugal fan without volute includes a rear wheel disc 1, blades 2, and a front wheel disc 3. The rear wheel disc 1 and the front wheel disc 3 are coaxially arranged, and the axis is recorded as the Z axis. The two ends of the rear wheel disc 1 are respectively open, wherein one end is a wide-diameter rear wheel disc outer edge 11, and the other end is a narrow-diameter center hole end 12. The rear wheel disc outer edge 11 and the center hole end 12 smoothly transition to a transition surface 13, and the transition surface 13 is located on the back side of the rear wheel disc 1 and is obliquely arranged toward the front wheel disc 3, so that the rear wheel disc 1 is a conical structure.

[0048] In some preferred embodiments, the front wheel disc 3 is a disc-shaped structure folded from the inside, and the two ends of the front wheel disc 3 are respectively open, wherein one end is a large-diameter front wheel disc outer edge 31, and the other end is a small-diameter front wheel disc inlet end 32, which is used to optimize the airflow flow at the inlet and reduce flow losses. The blade 2 is connected between the transition surface 13 of the rear wheel disc 1 and one end where the front wheel disc outer edge 31 of the front wheel disc 3 is located. The surface of the blade 2 is a three-dimensional curved surface in space. The number of the blades 2 is several, and the several blades 2 are arranged along the circumference of the wheel disc.

[0049] For ease of description, the direction of the fan rotation axis is marked as the Z axis, and the air flow direction flows from the negative direction of the Z axis to the positive direction.

[0050] Specifically, the blade 2 includes a rear blade root 21, a front blade root 22, an inlet edge 23, an outlet edge 24, a pressure surface 25, and a suction surface 26, wherein the curved surface connecting the blade 2 to the back of the rear wheel disc 1 is the rear blade root 21, the curved surface connecting the blade 2 to the back of the front wheel disc 3 is the front blade root 22, the inlet edge 23 is the edge where the airflow flows in, the outlet edge 24 is the edge where the airflow flows out, the pressure surface 25 is the surface where the blade 2 does work, the edge of the blade 2 adjacent to the rear wheel disc 1 is the trailing edge, the edge of the blade 2 adjacent to the front wheel disc 3 is the leading edge, the trailing edge of the outlet edge 24 is connected to one end of the transition surface 13 adjacent to the outer edge 11 of the rear wheel disc, and the trailing edge of the inlet edge 23 is connected to one end of the transition surface 13 adjacent to the center hole end 12.

[0051] As the blades 2 rotate, the rotating blades 2 suck air from the center, and then throw the air outward through centrifugal force to form an airflow, which is different from the general pipe flow. The general pipe flow has a higher velocity at the center and a lower velocity near the wall. However, in the centrifugal fan, the velocity distribution shows the opposite velocity distribution, with a high velocity at the edge and the lowest velocity near the center. For example, the wind speed at the leading edge of the inlet side 23 of the blade 2 is relatively high, and the center velocity is relatively low. The same velocity trend appears in the velocity cloud diagram of the rotating surface of the impeller inlet. Such a velocity distribution needs to be paid attention to when designing the blades, such as Fig.12 As shown, the red area is the high-speed area. To this end, in order to design a blade structure that matches the airflow characteristics in the flow field of a centrifugal fan without a volute, the applicant divides any blade 2 into sections along the airflow direction in the flow field of the centrifugal fan without a volute, and optimizes the inlet and outlet angles and chord length dimensions of each section.

[0052] Specifically, along the inlet and outlet direction of the Z axis, several cross sections are taken between the middle of the rear blade root 21 and the middle of the front blade root 22, wherein the cross section is a cross section of the blade 2 divided obliquely along the direction of the back side of the rear wheel disc 1, wherein the two cross sections located at the end portions capture the rear blade root 21 and the front blade root 22 respectively;

[0053] In each section, the contour line of the pressure surface 25 is the cross-sectional profile, and the angle between the two tangent lines at the end point where the inlet edge 23 is located in the cross-sectional profile is recorded as the inlet angle α, and the angle between the two tangent lines at the end point where the outlet edge 24 is located in the cross-sectional profile is recorded as the outlet angle β.

[0054] Along the front-to-rear direction from the front wheel disc 3 to the rear wheel disc 1, the inlet angle α of the section adjacent to the front wheel disc 3 is greater than the inlet angle α of the section adjacent to the rear wheel disc 1, and the inlet angle α of the section adjacent to the rear wheel disc 1 is greater than the inlet angle α of the section located in front of it; the outlet angle β of the section adjacent to the front wheel disc 3 is greater than the outlet angle β of the section located behind it, and the outlet angle β of the section adjacent to the rear wheel disc 1 is greater than the outlet angle β of the section located in front of it.

[0055] In some preferred embodiments, along the Z axis direction, five spaced sections are taken between the middle of the rear blade root 21 and the middle of the front blade root 22, and each section is a first section Q1, a second section Q2, a third section Q3, a fourth section Q4, and a fifth section Q5. The schematic diagrams of each section are shown in Figures 6 to 10 , wherein the first section Q1 captures the rear blade root 21, and the second section Q2 captures the front blade root 22, which are used to capture more sections and make full use of the airflow in the fan to design each section in detail, so as to effectively reduce turbulent dissipation and reduce power consumption.

[0056] Specifically, taking any cross-section among the cross-sections distributed at equal intervals as an example, on the pressure surface 25, the endpoint where the cross-section intersects with the inlet edge 23 is recorded as point N, and the endpoint where the cross-section intersects with the outlet edge 24 is recorded as point M. The intersection line of the cross-section and the pressure surface is curve NM, recorded as the cross-section profile line, and two tangents are drawn at points N and M, respectively, and are recorded as tangent A and tangent D, respectively.

[0057] Then, a straight line perpendicular to the transition surface 13 is drawn to intersect the Z axis, and the intersection point is located at the center of the center hole end 12. This straight line is recorded as the E-section line. Two perpendicular lines perpendicular to the direction of the E-section line are drawn from points N and M in the cross section. The intersection point of the two perpendicular lines at the E-section line is point O. In the plane where NMO is located, a front circle is drawn with the straight line distance of the straight line NO as the front edge radius. The front edge radius is recorded as R. NO The tangent line of the front circle at N is recorded as B tangent line. Similarly, in the plane where NMO is located, the rear circle is made with the straight line distance of the straight line MO as the rear edge radius. The rear edge radius is recorded as R MO The tangent line of the rear circle at M is recorded as G tangent line, the inlet angle α is ∠BNA, and the outlet angle β is ∠DMG.

[0058] The leading edge radii in the first section Q1, the second section Q2, the third section Q3, the fourth section Q4, and the fifth section Q5 are respectively denoted as R NO1 , R NO2 , R NO3 , R NO4 , R NO5 The trailing edge radii in the first section Q1, the second section Q2, the third section Q3, the fourth section Q4, and the fifth section Q5 are respectively denoted as R MO1 , R MO2 , R MO3 , R MO4 , R MO5 .

[0059] In some preferred embodiments, along the axis direction from the rear wheel disc 1 to the front wheel disc 3, at least five equally spaced cross sections are taken between the middle of the rear blade root 21 and the middle of the front blade root 22, and the cross-sectional line distribution of each cross section is as follows: Figure 3As shown, the cross section is a cross section of the blade 2 extending obliquely along the back side of the rear wheel disc 1. Along the direction from the rear wheel disc 1 to the front wheel disc 3, the cross sections are the first cross section Q1, the second cross section Q2, the third cross section Q3, the fourth cross section Q4, and the fifth cross section Q5. The inlet angle α of each cross section is α1, α2, α3, α4, and α5, respectively, wherein α5>α1>α2>α3>α4, and the outlet angle β of each cross section is β1, β2, β3, β4, and β5, respectively, wherein β5>β4, and β1>β2>β3>β4, so that each cross section of the blade 2 achieves optimal aerodynamic performance, reduces the resistance of the airflow when flowing through the flow channel, and obtains a uniform pressure rise near the outlet edge when the airflow flows out of the trailing edge of the blade, thereby improving the work efficiency of the fan.

[0060] In some preferred embodiments, in order to reduce the airflow loss at the inlet angle α, the design of the A tangent should be consistent with the airflow direction at the inlet edge 23 as much as possible. To achieve this goal, it can be achieved by adjusting the position angle γ of the inlet edge 23. However, since the airflow fields at different positions are different, if the same position angle γ is used, the airflow in the flow field cannot be efficiently utilized. For this reason, the applicant optimizes the position angle γ of each cross section so that the leading edge of the inlet edge 23 is convex.

[0061] Specifically, a vertical extension line is drawn along the Z-axis direction from point O in any section, the intersection of the vertical extension line and the section profile is H, and the position angle γ is ∠HON, wherein the position angles γ in the first section Q1, the second section Q2, the third section Q3, the fourth section Q4, and the fifth section Q5 are γ1, γ2, γ3, γ4, and γ5, respectively, the position angle γ3 of the third section Q3 is greater than the position angle γ2 of the second section Q2, and the position angle γ3 of the third section Q3 is greater than the position angle γ4 of the fourth section Q4, that is, γ3>γ2, and γ3>γ4, so that part of the leading edge of the inlet edge 23 is convex.

[0062] Furthermore, the trailing edge of the outlet edge 24 is concave, and the straight line distance between point N and point M in the cross section is the chord C, and the length of the chord C is d c , where the lengths of the chords in the first section Q1, the second section Q2, the third section Q3, the fourth section Q4, and the fifth section Q5 are respectively denoted as d c1 d c2 d c3 d c4 d c5 The lengths of the chord C in different sections are different, which makes the flow field on the pressure surface of the blade more uniform and further improves the impeller efficiency.

[0063] The reason why the trailing edge of the outlet edge 24 is set to be concave is that the trailing edge is a high pressure concentration area. If the trailing edge is set to a smooth contour, it will cause uneven pressure distribution at the trailing edge of each cross section. Fig.11 As shown, Fig.11 The pressure cloud diagram of the trailing edge under different shapes. Fig.11 In order to intuitively reflect the pressure distribution of various parts of the blade, different pressures in the blade are marked with different colors. Among them, the area at the end of the trailing edge is the high-pressure area, that is, the red area of ​​the cloud map. It can be seen from the figure that when the trailing edge is straight, the high-pressure area at the outlet is too concentrated, which is not conducive to the work of the impeller. After the trailing edge is set to a concave shape by this application, the pressure distribution near the outlet edge of the concave trailing edge is more uniform, and each section obtains a more uniform pressure rise at the trailing edge, which is conducive to improving the efficiency of the impeller.

[0064] In some preferred embodiments, the outlet edge 24 at the location of the second section Q2 is set to be concave, that is, the chord length d of the second section Q2 is c2 Less than the chord length d of the first section Q1 c1 , and the chord length d of the second section Q2 c2 is smaller than the chord length d of the third section Q3 c3 , making the pressure distribution near the outlet edge of the trailing edge concave more uniform.

[0065] The purpose of considering the static pressure efficiency of a voluteless centrifugal fan is to ensure that the fan can meet the air volume and air pressure requirements while optimizing the overall performance of the system and reducing energy consumption, thereby improving the energy efficiency and energy-saving level of the entire fan system, reducing carbon emissions, and saving operating costs. Therefore, static pressure efficiency is often used as a major indicator in this field to evaluate the performance of a voluteless centrifugal fan.

[0066] In the present application, by optimizing the design of the blade, the static pressure efficiency of each section of the blade basically reaches more than 70%, which can ensure that each area of ​​the blade works efficiently.

[0067] Specific examples are given below.

[0068] Embodiment 1:

[0069] The diameter of the rear wheel outer edge 11 of the rear wheel 1 598mm, center hole end 12 diameter The straight-line distance d1 between the outer edge 11 of the rear wheel disc and the center hole end 12 along the Z axis is 130 mm, and the diameter of the outer edge 31 of the front wheel disc is The diameter of the front wheel disc inlet end is 659mm For example, the straight-line distance from the center hole end 12 along the Z axis to the outer edge 31 of the front wheel disc along the Z axis is 270 mm.

[0070] Along the axis direction from the rear wheel disc 1 to the front wheel disc 3, five equally spaced sections are taken between the middle of the rear blade root 21 and the middle of the front blade root 22. The sections are the first section Q1, the second section Q2, the third section Q3, the fourth section Q4, and the fifth section Q5. The geometric dimensions of each section are shown in Table 1.1 below:

[0071] Table 1.1 Geometric parameters of each section

[0072]

[0073] The static pressure and static pressure efficiency data of this fan on the standard fan performance test bench are detailed in Fig.13 and Fig.14 .

[0074] Embodiment 2:

[0075] The diameter of the rear wheel outer edge 11 of the rear wheel 1 598mm, center hole end 12 diameter The straight-line distance d1 between the outer edge 11 of the rear wheel disc and the center hole end 12 along the Z axis is 130 mm, and the diameter of the outer edge 31 of the front wheel disc is The diameter of the front wheel disc inlet end is 659mm For example, the straight-line distance from the center hole end 12 along the Z axis to the outer edge 31 of the front wheel disc along the Z axis is 270 mm.

[0076] Along the axis direction from the rear wheel disc 1 to the front wheel disc 3, five equally spaced sections are taken between the middle of the rear blade root 21 and the middle of the front blade root 22. The sections are the first section Q1, the second section Q2, the third section Q3, the fourth section Q4, and the fifth section Q5. The geometric dimensions of each section are shown in Table 2.1 below:

[0077] Table 2.1 Geometric parameters of each section

[0078]

[0079] The static pressure and static pressure efficiency data of this fan on the standard fan performance test bench are detailed in Fig.13 and Fig.14 .

[0080] Comparative Example:

[0081] The diameter of the rear wheel outer edge 11 of the rear wheel 1 598mm, center hole end 12 diameter The straight-line distance d1 between the outer edge 11 of the rear wheel disc and the center hole end 12 along the Z axis is 130 mm, and the diameter of the outer edge 31 of the front wheel disc is The diameter of the front wheel disc inlet end is 659mm For example, the straight-line distance from the center hole end 12 along the Z axis to the outer edge 31 of the front wheel disc along the Z axis is 270 mm.

[0082] Along the axis direction from the rear wheel disc 1 to the front wheel disc 3, five equally spaced sections are taken between the middle of the rear blade root 21 and the middle of the front blade root 22. The sections are the first section Q1, the second section Q2, the third section Q3, the fourth section Q4, and the fifth section Q5. The geometric dimensions of each section are shown in Table 3.1 below:

[0083] Table 3.1 Geometric parameters of each section

[0084]

[0085] The static pressure and static pressure efficiency data of this fan on the standard fan performance test bench are detailed in Fig.13 and Fig.14 .

[0086] pass Fig.13 and Fig.14 Comparative analysis of the measured data shows that the blade flow channel design in Example 1 and Example 2 can minimize aerodynamic losses and noise levels, ensure that the air flow reaches the optimal state under rated conditions, and increase the impeller static pressure efficiency to an almost unprecedented level. According to the design logic, after actual measurement, the maximum static pressure efficiency is as high as 82%, but compared with Example 1 and Example 2, the maximum value of the impeller static pressure efficiency in the comparative example cannot reach 82%, which is a major breakthrough in this field.

[0087] The above is a detailed introduction to the specific implementation methods of the present application. For those skilled in the art, several improvements and modifications may be made to the present application without departing from the principles of the present application. These improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A backward plate-type three-dimensional flow blade centrifugal fan without a volute, comprising a rear wheel disc (1), a blade (2), and a front wheel disc (3), wherein the blade (2) is connected between the back side of the rear wheel disc (1) and the front wheel disc (3) which are coaxially arranged, and the surface of the blade (2) is a three-dimensional curved surface in space, characterized in that: The blade (2) comprises a rear blade root (21), a front blade root (22), an inlet edge (23), an outlet edge (24), a pressure surface (25), and a suction surface (26); the rear blade root (21) is a curved surface connecting the blade (2) and the back surface of the rear wheel disc (1); and the front blade root (22) is a curved surface connecting the blade (2) and the back surface of the front wheel disc (3); Along the inlet and outlet direction of the Z axis, a plurality of cross sections are taken between the middle of the rear blade root (21) and the middle of the front blade root (22), wherein the cross sections are cross sections of the blade (2) obliquely divided along the direction where the blade (2) is attached to the back of the rear wheel disc (1), wherein the two cross sections located at the end portions capture the rear blade root (21) and the front blade root (22) respectively; In each cross section, the contour line of the pressure surface (25) is the cross-sectional profile, and the angle between two tangent lines at the end point where the inlet edge (23) of the cross-sectional profile is located is recorded as the inlet angle α, and the angle between two tangent lines at the end point where the outlet edge (24) of the cross-sectional profile is located is recorded as the outlet angle β; Along the front-to-rear direction from the front wheel disc (3) to the rear wheel disc (1), the inlet angle α of the section adjacent to the front wheel disc (3) is greater than the inlet angle α of the section adjacent to the rear wheel disc (1), and the inlet angle α of the section adjacent to the rear wheel disc (1) is greater than the inlet angle α of the section located in front of it; the outlet angle β of the section adjacent to the front wheel disc (3) is greater than the outlet angle β of the section located behind it, and the outlet angle β of the section adjacent to the rear wheel disc (1) is greater than the outlet angle β of the section located in front of it.

2. The backward plate-type three-dimensional flow blade centrifugal fan without volute according to claim 1, characterized in that: The inlet angle α and outlet angle β of each section are made by the following methods: On the pressure surface (25), the end point where the cross section intersects the inlet edge (23) is recorded as point N, the end point where the cross section intersects the outlet edge (24) is recorded as point M, the intersection line of the cross section and the pressure surface is a curve NM, recorded as a cross section profile, and two tangents are drawn at the points N and M, respectively, and are recorded as tangent A and tangent D, respectively; A straight line is then drawn perpendicular to the back side of the rear wheel disc (1) and intersecting with the Z axis line, with the intersection point being located at the center of the center hole end (12) of the rear wheel disc (1). The straight line is recorded as the E-section line. Two perpendicular lines are drawn from points N and M in the cross section and perpendicular to the direction of the E-section line. The intersection point of the two perpendicular lines at the E-section line is O. In the plane where NMO is located, a front circle is drawn with the straight line NO as the leading edge radius. The tangent of the front circle at point N is recorded as the B-tangent line. Similarly, in the plane where NMO is located, a rear circle is drawn with the straight line MO as the trailing edge radius. The tangent of the rear circle at point M is recorded as the C-tangent line. The inlet angle is ∠BNA and the outlet angle is ∠DMC.

3. The backward plate-type three-dimensional flow blade centrifugal fan without volute according to claim 2, characterized in that: Along the Z axis direction, at least five spaced sections are taken between the middle of the rear blade root (21) and the middle of the front blade root (22), and each section is a first section (Q1), a second section (Q2), a third section (Q3), a fourth section (Q4), and a fifth section (Q5). The inlet angle α of each section is α1, α2, α3, α4, and α5, respectively, wherein α5>α1>α2>α3>α4, and the outlet angle β of each section is β1, β2, β3, β4, and β5, respectively, wherein β5>β4, and β1>β2>β3>β4.

4. The backward plate-type three-dimensional flow blade centrifugal fan without volute according to claim 3, characterized in that: The inlet angle α1 of the first section (Q1) ranges from 7.6° to 15.6°, the inlet angle α2 of the second section (Q2) ranges from 4.6° to 12.6°, and the inlet angle α5 of the fifth section (Q5) ranges from 12.9° to 20.9°.

5. The backward plate-type three-dimensional flow blade centrifugal fan without volute according to claim 3, characterized in that: The inlet angle α3 of the third section (Q3) ranges from 3.2° to 11.2°, and the inlet angle α4 of the fourth section (Q4) ranges from 1.7° to 9.7°.

6. The backward plate-type three-dimensional flow blade centrifugal fan without volute according to claim 3, characterized in that: The outlet angle β1 of the first section (Q1) ranges from 39.3° to 43.3°, and the outlet angle β2 of the second section (Q2) ranges from 32.5° to 36.5°.

7. The backward plate-type three-dimensional flow blade centrifugal fan without volute according to claim 3, characterized in that: The outlet angle β4 of the fourth section (Q4) ranges from 29.1° to 33.1°, and the outlet angle β5 of the fifth section (Q5) ranges from 30.6° to 34.6°.

8. The backward plate-type three-dimensional flow blade centrifugal fan without volute according to claim 3, characterized in that: The value range of the outlet angle β3 of the third section (Q3) is 29.7°-33.7°.

9. The backward plate-type three-dimensional flow blade centrifugal fan without volute according to claim 2, characterized in that: A vertical extension line is drawn along the Z-axis direction at point O in any section, the intersection of the vertical extension line and the section profile is H, and ∠HON is recorded as the position angle γ, wherein the position angle γ3 of the third section (Q3) is greater than the position angle γ2 of the second section Q2, and the position angle γ3 of the third section (Q3) is greater than the position angle γ4 of the fourth section (Q4), so that a portion of the leading edge of the inlet edge (23) is convex.

10. The backward plate-type three-dimensional flow blade centrifugal fan without volute according to claim 3, characterized in that: The trailing edge of the outlet edge (24) is concave, and the chord lengths C of the various cross sections are different.

11. The backward plate-type three-dimensional flow blade centrifugal fan without volute according to claim 10, characterized in that: The outlet edge (24) where the second section (Q2) is located is set to be concave, that is, the chord length d of the second section (Q2) is c2 Less than the chord length d of the first section (Q1) c1 , and the chord length d of the second section (Q2) c2 Less than the chord length d of the third section (Q3) c3 .

Images