A high-efficiency low-noise medium-pressure centrifugal fan

Abstract

The application relates to the technical field of centrifugal fans, in particular to a high-efficiency low-noise medium-pressure centrifugal fan, which comprises a volute, an impeller and a flow collector, the impeller is arranged in the volute, and the flow collector is arranged outside the volute and fixedly connected with the volute; the impeller comprises a back disc, a plurality of blades are arranged around the back disc, the blades comprise long blades and short blades, and the long blades and the short blades are arranged at intervals; the profile line of the volute comprises a first diffuser straight section, a volute tongue section, a first arc section, a second arc section, a third arc section, a fourth arc section, a first diffuser arc section, a second diffuser arc and a second diffuser straight section which are connected in sequence and are tangent to each other, the first diffuser straight section and the second diffuser straight section enclose a circular air outlet, the first diffuser arc section and the second diffuser arc are circumscribed, and the first arc section, the second arc section, the third arc section and the fourth arc section are all non-concentric and the centers form a square. The high-efficiency low-noise medium-pressure centrifugal fan has higher pressure, higher efficiency and lower noise.

Description

Technical Field

[0001] This invention relates to the field of centrifugal fan technology, and in particular to a high-efficiency, low-noise medium-pressure centrifugal fan. Background Technology

[0002] Medium-pressure centrifugal fans are centrifugal fans that can balance large air volume with stable operating efficiency. They can meet the needs of many occasions that require overcoming certain pipeline resistance for air supply, exhaust and material conveying, and are widely used in industrial and civil ventilation fields.

[0003] Currently, medium-pressure centrifugal fans generally suffer from problems such as insufficient pressure, low efficiency, and high operating noise, which are not conducive to energy conservation, emission reduction, and environmental protection, and also fail to meet the needs of society and users.

[0004] Existing technology needs improvement. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency, low-noise medium-pressure centrifugal fan, which aims to solve the problems of insufficient pressure, low efficiency, and high operating noise that are common in existing medium-pressure centrifugal fans.

[0006] To achieve the above objectives, a high-efficiency, low-noise medium-pressure centrifugal fan is provided, comprising a volute, an impeller, and a collector. The impeller is disposed inside the volute, and the collector is disposed outside the volute and fixedly connected to the volute. The impeller includes a rear plate, on which multiple blades are arranged in an array. The blades include long blades and short blades, which are spaced apart.

[0007] The profile of the volute includes a first diffuser straight section, a volute tongue section, a first arc section, a second arc section, a third arc section, a fourth arc section, a first diffuser arc section, a second diffuser arc section, and a second diffuser straight section connected tangentially in sequence. The first diffuser straight section and the second diffuser straight section enclose and form a circular air outlet. The first diffuser arc section and the second diffuser arc section are externally tangent. The first arc section, the second arc section, the third arc section, and the fourth arc section are not concentric and their centers form a square.

[0008] A rectangular coordinate system is established with the impeller center O as the origin. When the first diffuser section is located in the fourth quadrant, the coordinates of the center O1 of the first arc section are (12, 12), the radius R4 is 209mm-211mm, and the arc length is 155mm-158mm. The coordinates of the center O2 of the second arc section are (-12, 12), the radius R5 is 232.8mm-235.2mm, and the arc length is 365.5mm-369.5mm. The coordinates of the center O3 of the third arc section are (-12, -12), the radius R6 is 256.5mm-259.5mm, and the arc length is 403mm-407.5mm. The coordinates of the center O4 of the fourth arc section are (12, -12), the radius R7 is 280.2mm-283.8mm, and the arc length is 428.5mm-433.5mm. The first diffuser section and the second diffuser section are parallel.

[0009] Furthermore, the diameter of the air outlet φ8 is 116mm-126mm, the length of the first diffuser straight section L16 is 49mm-51mm, the radius of the volute tongue section R3 is 4.9mm-5.1mm and the arc length is 11mm-12mm, the radius of the first diffuser arc section R8 is 412mm-415mm and the arc length is 158mm-160mm, the radius of the second diffuser arc section R9 is 49.5mm-50.5mm and the arc length is 19mm-19.5mm, and the length of the second diffuser straight section L17 is 45.2mm-46.8mm;

[0010] A tangent is drawn to the cochlear tongue segment at the point of tangency between the cochlear tongue segment and the first arc segment. The angle ∠8 between this tangent and the first diffuser straight segment is 46°-48°.

[0011] The inner wall of the volute is coated with a nano-sound-absorbing coating.

[0012] Furthermore, the circumference diameter φ4 formed by the outermost ends of all long blades and all short blades is 360mm, the circumference diameter φ5 formed by the innermost ends of all long blades is 100mm-104mm, and the circumference diameter φ6 formed by the innermost ends of all short blades is 196mm-204mm.

[0013] When installing long blades, the inlet angle ∠2 is 141°-144°, and the outlet angle ∠3 is 90.5°-91.5°.

[0014] When installing short blades, the inlet angle ∠4 is 94°-96°, and the outlet angle ∠5 is 89.6°-90.4°.

[0015] There are 12 long leaves and 12 short leaves.

[0016] Furthermore, the long blade includes a leading edge, a trailing edge, a first side of the long blade connecting the first end of the leading edge and the trailing edge, and a second side of the long blade connecting the second end of the leading edge and the trailing edge. The first side of the long blade is the side away from the rear plate, and the second side of the long blade is the side close to the rear plate. The leading edge of the long blade is set as a biomimetic wave-shaped structure, and the trailing edge of the long blade is parallel to the hub of the impeller.

[0017] The thickness of the long blade decreases linearly from the leading edge to the trailing edge.

[0018] Furthermore, in the direction from the leading edge of the long blade to the trailing edge of the long blade, the first side of the long blade includes an arc segment and a straight segment.

[0019] On the projection surface of the rear disc, the maximum thickness t1 of the long blade arc segment is 4.8mm-5.2mm, the minimum thickness t2 is 4.0mm-4.3mm, the blade midpoint radius R2 of the long blade arc segment is 104mm-106mm and the arc length is 68mm-72mm, the minimum thickness t3 of the long blade straight segment is 2.9mm-3.1mm, and the length L3 of the long blade straight segment is 76mm-78mm.

[0020] The impeller is cut along a plane passing through its central axis. In the cross-section: the width L5 of the leading edge of the long blade is 50.5mm-53.5mm, the width L6 of the trailing edge of the long blade is 34mm-36mm, the wavelength L7 of the wavy structure is 14.5mm-15.5mm, and the amplitude L8 is 1.15mm-1.25mm.

[0021] Furthermore, the long blades also have multiple recesses arranged in a rectangular array;

[0022] The impeller is sectioned by a plane passing through its central axis. On the cross-section:

[0023] The diameter of the pit φ7 is 2.9mm-3.1mm, and the depth of the pit is 0.9mm-1.1mm;

[0024] With the direction perpendicular to the rear plate as the longitudinal direction and the direction parallel to the rear plate as the transverse direction, the pits are set to 18 rows in the transverse direction and 8 columns in the longitudinal direction;

[0025] The distance between the centers of two adjacent dimples in each row is L12, and the distance between the centers of two adjacent dimples in each column is L13. L12 and L13 are equal and both are 3.8mm-4.2mm.

[0026] The distance L15 between the center of the row of pits near the rear plate and the rear plate is 4.7mm-5.3mm, and the distance L14 between the center of the row of pits near the trailing edge of the long blade is 5.1mm-5.9mm.

[0027] Furthermore, the short blade includes a leading edge, a trailing edge, a first side connecting the leading edge and the trailing edge, and a second side connecting the leading edge and the trailing edge. The first side is the side away from the rear disc, the second side is the side closer to the rear disc, the trailing edge is set as a biomimetic sawtooth structure, and the leading edge is parallel to the impeller hub.

[0028] The thickness of the short blade decreases linearly from the leading edge to the trailing edge.

[0029] Furthermore, from the leading edge to the trailing edge of the short blade, the short blade has a straight structure;

[0030] On the projection surface of the rear disc, the maximum thickness t4 of the short blade is 4.8mm-5.2mm, the minimum thickness t5 is 2.9mm-3.1mm, and the length L4 of the short blade is 79mm-81mm.

[0031] The impeller is cut along a plane passing through its central axis. In the cross-section: the width L9 of the leading edge of the short blades is 41mm-43mm, the tooth pitch L10 of the serrated structure is 6.8mm-7.2mm, and the tooth depth L11 is 2.9mm-3.1mm.

[0032] Five sawtooth structures are set.

[0033] Furthermore, the collector includes an integrally formed connecting part and a front cover plate. A guide section is formed in the middle of the side of the front cover plate away from the impeller. The guide section includes a trumpet-shaped constriction section and a collecting ring. The collector is fixedly connected to the volute through the connecting part. The inner circumference of the trumpet-shaped opening of the constriction section forms an air inlet. The outlet of the collecting ring is annular and the inner circumference forms an air guide. The outlet of the front cover plate near the impeller is annular and the inner circumference forms an air intake.

[0034] An axial clearance is provided between the collector and the impeller.

[0035] Furthermore, the diameter of the air inlet φ1 is 143mm-147mm, the diameter of the air guide φ2 is 127.5mm-130.5mm, and the diameter of the air exhaust φ3 is 376mm-382mm.

[0036] The collector is cut along a plane passing through its central axis. In the cross-section: the radius R1 of the constriction section is 7.6mm-8.4mm and the arc length is 11.4mm-13.4mm; the vertical distance L1 between the air inlet and the air guide is 19mm-21mm; the vertical distance L2 between the air guide and the air outlet is 1.9mm-2.1mm; and the included angle ∠1 formed between the connecting part and the front cover is 8°-8.3°.

[0037] The axial clearance L18 between the collector and the impeller is 13mm-14.5mm.

[0038] Compared with the prior art, the high-efficiency and low-noise medium-pressure centrifugal fan provided by the present invention has the following beneficial effects:

[0039] (1) By designing the volute profile of the shell cavity and spiral line data through the biomimetic spiral shell-ammonia structure, the flow loss near the volute wall and the airflow friction in the flow channel can be effectively reduced, making the airflow smooth and uniform, improving the static pressure recovery coefficient of the volute, reducing the operating noise of the fan, and improving the aerodynamic performance of the fan; furthermore, the nano sound-absorbing coating is sprayed on the inner wall of the volute to further absorb noise, which is beneficial to reducing the noise of the fan.

[0040] (2) By designing biomimetic airfoil-shaped long blades, the thickness of the long blades decreases linearly from the leading edge to the trailing edge, which can effectively adapt to the airflow direction, reduce impact separation loss, reduce frictional resistance at the outlet end, and improve the efficiency of the fan; further, by biomimetic designing the leading edge of the long blades into a wave-shaped structure, the long blades generate micro-vortices through the wave-shaped protrusion structure, which can break the large-area airflow separation vortex, effectively delay the separation of the airflow boundary layer, improve the smoothness of airflow, and further improve the efficiency of the fan.

[0041] (3) By designing a linear array of recessed structures on the suction surface of the long blades, the airflow boundary layer is optimized by utilizing the recessed structure, reducing the airflow friction of the long blades, reducing energy loss, further improving the total pressure of the fan and reducing the fan noise;

[0042] (4) By designing biomimetic airfoil-shaped short blades, the thickness of the short blades decreases linearly from the leading edge to the trailing edge, which can effectively adapt to the airflow direction, reduce impact separation loss, reduce frictional resistance at the outlet end, and improve the efficiency of the fan; furthermore, by biomimetic designing the trailing edge of the short blades into a sawtooth structure, the triangular sawtooth structure can cut the large-scale vortex that falls off the trailing edge of the short blades, converting high-frequency noise into low-intensity broadband noise, and significantly reducing aerodynamic noise;

[0043] (5) The connecting part of the collector and the front cover are integrally die-cast aluminum and transitioned with a large arc. By designing a trumpet-shaped constriction section and a guide ring structure at the air inlet end of the middle of the front cover, when the fan is running, the airflow can be evenly distributed on the impeller inlet section under the collection and guidance of the guide section, and enter the impeller with minimal airflow loss, thereby improving the fan performance and increasing the fan efficiency. Attached Figure Description

[0044] Figure 1This is a schematic diagram of the structure of a high-efficiency, low-noise medium-pressure centrifugal fan according to the present invention;

[0045] Figure 2 This is a schematic diagram of the profile of the volute.

[0046] Figure 3 This is a schematic diagram of a partial sectional view of the volute.

[0047] Figure 4 This is a schematic diagram of the three-dimensional structure of the volute.

[0048] Figure 5 This is a schematic diagram of the impeller structure;

[0049] Figure 6 This is a schematic diagram of the side sectional view of the impeller;

[0050] Figure 7 This is a schematic diagram of the three-dimensional structure of the impeller;

[0051] Figure 8 This is a half-sectional side view of the collector;

[0052] Figure 9 This is a performance curve diagram of the present invention;

[0053] Figure 10 This is a performance curve graph with a proportional ratio.

[0054] Explanation of reference numerals in the attached figures:

[0055] 1. Volute; 11. First diffuser straight section; 12. Volute tongue section; 13. First arc section; 14. Second arc section; 15. Third arc section; 16. Fourth arc section; 171. First diffuser arc section; 172. Second diffuser arc section; 18. Second diffuser straight section; 19. Air outlet.

[0056] Impeller 2; Long blade 21; Leading edge of long blade 211; Trailing edge of long blade 212; Arc section of long blade 213; Straight section of long blade 214; Dent 215; Short blade 22; Leading edge of short blade 221; Trailing edge of short blade 222; Back plate 23;

[0057] Collector 3; Connector 31; Front cover 32; Narrow section 33; Collector ring 34; Air inlet 35; Air guide 36; Air exhaust 37;

[0058] 4 motors; 5 bases. Detailed Implementation

[0059] The present invention will be described in detail below with reference to specific embodiments.

[0060] In this invention, unless otherwise explicitly specified and limited, terms such as "set in," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or a connection through one or more intermediate media. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The directional terms appearing in this invention are for the purpose of better describing the characteristics of the features and the relationships between them. It should be understood that when the orientation of this invention changes, the orientation of the characteristics of the features and the relationships between them also changes accordingly. Therefore, directional terms do not constitute an absolute spatial limitation on the characteristics of the features and the relationships between them, but only a relative limitation.

[0061] The structural parameters used in this invention are only for illustrating the technical solution of this invention. That is, based on the basic structural parameters of this invention, reasonable proportional scaling can be performed in actual production (for example, when the diameter of the outer circumference circle formed by the outer ends of all the blades of the impeller is 360mm, it can be scaled by 0.1-30 times, etc.). Such reasonable proportional scaling also falls within the protection scope of this invention.

[0062] Please see Figure 1-10 A high-efficiency, low-noise medium-pressure centrifugal fan includes a volute 1, an impeller 2, and a collector 3. The impeller 2 is disposed inside the volute 1, and the collector 3 is disposed outside the volute 1 and fixedly connected to the volute 1. The impeller 2 includes a rear plate 23, on which multiple blades are arranged in an array. The blades include long blades 31 and short blades 22, which are spaced apart.

[0063] The profile of the volute 1 includes a first diffuser straight section 11, a volute tongue section 12, a first arc section 13, a second arc section 14, a third arc section 15, a fourth arc section 16, a first diffuser arc section 171, a second diffuser arc section 172, and a second diffuser straight section 18 connected tangentially in sequence. The first diffuser straight section 11 and the second diffuser straight section 18 enclose and form a circular air outlet 19. The first diffuser arc section 171 and the second diffuser arc section 172 are externally tangent. The first arc section 13, the second arc section 14, the third arc section 15, and the fourth arc section 16 are not concentric and their centers form a square.

[0064] A rectangular coordinate system is established with the center O of impeller 2 as the origin. When the first diffuser section 11 is located in the fourth quadrant, the coordinates of the center O1 of the first arc section 13 are (12, 12), the radius R4 is 209mm-211mm, and the arc length is 155mm-158mm. The coordinates of the center O2 of the second arc section 14 are (-12, 12), the radius R5 is 232.8mm-235.2mm, and the arc length is 365.5mm-369mm. The third arc segment 15 has a center O3 coordinate of (-12, -12), a radius R6 of 256.5mm-259.5mm, and an arc length of 403mm-407.5mm. The fourth arc segment 16 has a center O4 coordinate of (12, -12), a radius R7 of 280.2mm-283.8mm, and an arc length of 428.5mm-433.5mm. The first diffuser straight segment 11 and the second diffuser straight segment 18 are parallel. Preferably, R4 is 210mm and the arc length is 156.6mm, R5 is 234mm and the arc length is 367.6mm, R6 is 258mm and the arc length is 405.3mm, and R7 is 282mm and the arc length is 431mm.

[0065] Through the above technical solution, the volute profile of the shell cavity and spiral line data designed by the biomimetic spiral shell-ammonia structure can effectively reduce the flow loss near the wall of the volute 1 and the airflow friction in the flow channel, so that the airflow is stable and uniform, improves the static pressure recovery coefficient of the volute 1, reduces the operating noise of the fan, and improves the aerodynamic performance of the fan.

[0066] In this embodiment, the diameter φ8 of the air outlet 19 is 116mm-126mm, the length L16 of the first diffuser straight section 11 is 49mm-51mm, the radius R3 of the volute tongue section 12 is 4.9mm-5.1mm and the arc length is 11mm-12mm, the radius R8 of the first diffuser arc section 171 is 412mm-415mm and the arc length is 158mm-160mm, and the radius R9 of the second diffuser arc section 172 is... The length of the second diffuser straight section 18 is 45.2mm-46.8mm, with an arc length of 19mm-19.5mm and a diameter of 49.5mm-50.5mm. Preferably, φ8 is 121mm, L16 is 50mm, R3 is 5mm and has an arc length of 11.6mm, R8 is 413.4mm and has an arc length of 159.1mm, R9 is 50mm and has an arc length of 19.2mm, and L17 is 46mm.

[0067] A tangent line is drawn to the volute segment 12 with the tangent point between the volute segment 12 and the first arc segment 13 as the tangent point. The angle ∠8 between this tangent line and the first diffuser straight segment 11 is 46°-48°; preferably, ∠8 is 47.3°.

[0068] The inner wall of the volute 1 is coated with a nano sound-absorbing coating.

[0069] Through the above technical solution, by optimizing the design parameters of the volute 1 and matching and improving the structure of the impeller 2 and collector 3 (described later), the fan performance is improved, the fan efficiency is increased, and the noise is reduced. The nano-sound-absorbing coating sprayed onto the inner wall of the volute 1 enhances noise absorption, further reducing fan noise. It should be noted that the nano-sound-absorbing coating used for spraying is a commercially available coating and is not an improvement of this invention. Those skilled in the art can select coatings with different sound absorption properties according to product needs, and therefore will not be elaborated further.

[0070] In this embodiment, the circumferential diameter φ4 formed by the outermost ends of all long blades 21 and all short blades 22 is 360mm, the circumferential diameter φ5 formed by the innermost ends of all long blades 21 is 100mm-104mm, and the circumferential diameter φ6 formed by the innermost ends of all short blades 22 is 196mm-204mm; preferably, φ5 is 102mm and φ6 is 200mm.

[0071] When the long blade 21 is installed, the inlet angle ∠2 is 141°-144°, and the outlet angle ∠3 is 90.5°-91.5°; preferably, ∠2 is 142.5° and ∠3 is 91°.

[0072] When the short blade 22 is installed, the inlet angle ∠4 is 94°-96°, and the outlet angle ∠5 is 89.6°-90.4°; preferably, ∠4 is 95° and ∠5 is 90°.

[0073] There are 12 long leaves 21 and 12 short leaves 22.

[0074] By optimizing the installation and matching parameters of the impeller and blades through the above technical solutions, and combining the design of the long blade 21 and short blade 22 with multi-morphological biomimetic structure coupling described later, the efficiency of the fan can be effectively improved and the noise of the fan can be reduced.

[0075] In this embodiment, the long blade 21 includes a leading edge 211, a trailing edge 212, a first side of the long blade connected between the first ends of the leading edge 211 and the trailing edge 212, and a second side of the long blade connected between the second ends of the leading edge 211 and the trailing edge 212. The first side of the long blade is the side away from the rear disc 23, and the second side of the long blade is the side close to the rear disc 23. The leading edge 211 of the long blade is set as a biomimetic wave-shaped structure, and the trailing edge 212 of the long blade is parallel to the hub of the impeller 2.

[0076] The thickness of the long blade 21 decreases linearly from the leading edge 211 to the trailing edge 212.

[0077] Through the above technical solution, by designing a biomimetic airfoil-shaped long blade 21, the thickness of the long blade 21 decreases linearly from the leading edge 211 to the trailing edge 212, which can effectively adapt to the airflow direction, reduce impact separation loss, reduce frictional resistance at the outlet end, and improve the efficiency of the fan.

[0078] In this embodiment, from the leading edge 211 of the long blade to the trailing edge 212 of the long blade, the first side of the long blade includes an arc segment 213 and a straight segment 214.

[0079] On the projection surface of the rear disc 23, the maximum thickness t1 of the long blade arc segment 213 is 4.8mm-5.2mm, the minimum thickness t2 is 4.0mm-4.3mm, the blade midpoint radius R2 of the long blade arc segment 213 is 104mm-106mm and the arc length is 68mm-72mm, the minimum thickness t3 of the long blade straight segment 214 is 2.9mm-3.1mm, and the length L3 of the long blade straight segment 214 is 76mm-78mm; preferably, t1 is 5mm, t2 is 4.15mm, R2 is 105mm and the arc length is 69.2mm, t3 is 3mm, and L3 is 77mm;

[0080] The impeller 2 is sectioned along a plane passing through its central axis. In the section: the width L5 of the leading edge 211 of the long blades is 50.5mm-53.5mm; the width L6 of the trailing edge 212 of the long blades is 34mm-36mm; the wavelength L7 of the wavy structure is 14.5mm-15.5mm; and the amplitude L8 is 1.15mm-1.25mm. Preferably, L5 is 52mm, L6 is 35mm, L7 is 15mm, and L8 is 1.2mm.

[0081] Through the above technical solution, by designing a biomimetic airfoil-shaped long blade 21, the thickness of the long blade 21 decreases linearly from the leading edge 211 to the trailing edge 212, which can effectively adapt to the airflow direction, reduce impact separation loss, reduce outlet friction resistance, and improve fan efficiency. Furthermore, by biomimetically designing the leading edge 211 of the long blade as a wave-shaped structure, the long blade 21 generates micro-vortices through the wave-like protrusion structure, which can break the large-area airflow separation vortex, effectively delay the separation of the airflow boundary layer, improve airflow smoothness, and further improve fan efficiency.

[0082] In this embodiment, the long blade 21 also has a rectangular array of multiple pits 215;

[0083] Take a section of impeller 2 with a plane passing through the central axis of impeller 2. On the cross-section:

[0084] The diameter φ7 of the recess 215 is 2.9mm-3.1mm, and the depth of the recess 215 is 0.9mm-1.1mm; preferably, φ7 is 3mm, and the depth of the recess 215 is 1mm.

[0085] With the direction perpendicular to the rear plate 23 as the longitudinal direction and the direction parallel to the rear plate 23 as the transverse direction, the recess 215 is set to 18 rows in the transverse direction and 8 columns in the longitudinal direction;

[0086] The distance between the centers of two adjacent recesses 215 in each row is L12, and the distance between the centers of two adjacent recesses 215 in each column is L13. L12 and L13 are equal and both are 3.8mm-4.2mm; preferably, L12 and L13 are equal and both are 4mm.

[0087] The distance L15 between the center of the row of recesses 215 near the rear plate 23 and the rear plate 23 is 4.7mm-5.3mm, and the distance L14 between the center of the row of recesses 215 near the trailing edge of the long blade 212 and the trailing edge of the long blade 212 is 5.1mm-5.9mm. Preferably, L15 is 5mm and L14 is 5.5mm.

[0088] Through the above technical solution, by designing a linear array of recesses 215 on the suction surface of the long blade 21, the airflow boundary layer is optimized by utilizing the recesses 215 structure, reducing some of the airflow friction of the long blade 21, reducing energy loss, further improving the total pressure of the fan and reducing the fan noise.

[0089] In this embodiment, the short blade 22 includes a leading edge 221, a trailing edge 222, a first side of the short blade connected between the first ends of the leading edge 221 and the trailing edge 222, and a second side of the short blade connected between the second ends of the leading edge 221 and the trailing edge 222. The first side of the short blade is the side away from the rear disc 23, and the second side of the short blade is the side close to the rear disc 23. The trailing edge 222 of the short blade is set as a biomimetic sawtooth structure, and the leading edge 221 of the short blade is parallel to the hub of the impeller 2.

[0090] The thickness of the short blade 22 decreases linearly from the leading edge 221 to the trailing edge 222.

[0091] Through the above technical solution, by designing a biomimetic airfoil-shaped short blade 22, the thickness of the short blade 22 decreases linearly from the leading edge 221 to the trailing edge 222, which can effectively adapt to the airflow direction, reduce impact separation loss, reduce frictional resistance at the outlet end, and improve the efficiency of the fan.

[0092] Furthermore, from the leading edge 221 of the short blade to the trailing edge 222 of the short blade, the short blade 22 has a straight structure;

[0093] On the projection surface of the rear disc 23, the maximum thickness t4 of the short blade 22 is 4.8mm-5.2mm, the minimum thickness t5 is 2.9mm-3.1mm, and the length L4 of the short blade 22 is 79mm-81mm; preferably, t4 is 5mm, t5 is 3mm, and L4 is 80mm.

[0094] The impeller 2 is cut along a plane passing through its central axis. In the cross-section, the width L9 of the leading edge 221 of the short blade is 41mm-43mm, the tooth pitch L10 of the serrated structure is 6.8mm-7.2mm, and the tooth depth L11 is 2.9mm-3.1mm; preferably, L9 is 42mm, L10 is 7mm, and L11 is 3mm.

[0095] Five sawtooth structures are set.

[0096] Through the above technical solution, by designing a biomimetic airfoil-shaped short blade 22, the thickness of the short blade 22 decreases linearly from the leading edge 221 to the trailing edge 222, which can effectively adapt to the airflow direction, reduce impact separation loss, reduce outlet friction resistance, and improve wind turbine efficiency. Furthermore, by biomimeticly designing the trailing edge 222 of the short blade as a sawtooth structure, the triangular sawtooth structure can cut up the large-scale vortex that falls off the trailing edge 222 of the short blade, converting high-frequency noise into low-intensity broadband noise, and significantly reducing aerodynamic noise.

[0097] In this embodiment, the collector 3 includes an integrally formed connecting part 31 and a front cover plate 32. A guide section is formed in the middle of the side of the front cover plate 32 away from the impeller 2. The guide section includes a trumpet-shaped constriction section 33 and a collecting ring 34. The collector 3 is fixedly connected to the volute 1 through the connecting part 31. An air inlet 35 is formed on the inner circumference of the trumpet-shaped opening of the constriction section 33. The outlet of the collecting ring 34 is annular and an air guide 36 is formed on the inner circumference. The outlet of the front cover plate 32 near the impeller 2 is annular and an air duct 37 is formed on the inner circumference.

[0098] An axial clearance is provided between the collector 3 and the impeller 2.

[0099] Through the above technical solution, the connecting part 31 and the front cover plate 32 of the collector 3 are integrally die-cast aluminum and transition with a large arc. By designing a trumpet-shaped constriction section 33 and a guide ring 34 structure at the middle air inlet 35 end of the front cover plate 32, when the fan is running, the airflow can be evenly distributed on the inlet section of the impeller 2 under the collection and guidance of the guide section, and enter the impeller 2 with minimal airflow loss, thereby improving the fan performance and increasing the fan efficiency.

[0100] In this embodiment, the diameter φ1 of the air inlet 35 is 143mm-147mm, the diameter φ2 of the air guide 36 is 127.5mm-130.5mm, and the diameter φ3 of the air outlet 37 is 376mm-382mm; preferably, φ1 is 145mm, φ2 is 129mm, and φ3 is 379mm.

[0101] The collector 3 is cut along a plane passing through its central axis. In the cross-section: the radius R1 of the constricted section 33 is 7.6mm-8.4mm and the arc length is 11.4mm-13.4mm; the vertical distance L1 between the air inlet 35 and the air guide 36 is 19mm-21mm; the vertical distance L2 between the air guide 36 and the air outlet 37 is 1.9mm-2.1mm; and the included angle ∠1 formed between the connecting part 31 and the front cover plate 32 is 8°-8.3°. Preferably, R1 is 8mm and the arc length is 12.4mm, L1 is 20mm, L2 is 2mm, and ∠1 is 8.15°.

[0102] The axial clearance L18 between the collector 3 and the impeller 2 is 13mm-14.5mm. Preferably, L18 is 13.7mm.

[0103] Through the above-mentioned technical solutions, the improved matching of volute 1 and impeller 2, and the optimized parameters of collector 3, can better adapt to the operating requirements of the fan, improve fan performance, increase fan efficiency, and reduce fan noise.

[0104] It should be noted that the high-efficiency, low-noise medium-pressure centrifugal fan of this application also includes a motor 4 and a base 5. The motor 4 is connected to the impeller 2 via a transmission shaft, and the volute 1 is fixedly mounted on the base 5. Since the essential components such as the motor 4 and the base 5 involved in this invention are not improvements of this invention, and those skilled in the art are familiar with the structure and working principle of the basic components, they will not be described in detail here.

[0105] To verify this embodiment, based on the preferred structural parameters provided in this embodiment, a high-efficiency, low-noise medium-pressure centrifugal fan was tested using an impeller 2 with a diameter of 370 mm (i.e., the diameter of the outer circumference formed by the outer ends of all the long blades 21 and all the short blades 22 of the impeller 2). Simultaneously, a conventional medium-pressure centrifugal fan with a conventional impeller 2 and a diameter of 370 mm was tested as a comparative example. The test results were converted to atmospheric pressure of 101325 Pa, atmospheric temperature of 20 ℃, fan speed of 2900 r / min, and medium density of 1.2 kg / m³. 3 Test data under test conditions, and test examples yielded the test data shown in Table 1. Figure 9 The performance curves shown are used to derive test data as shown in Table 2. Figure 10The performance curves shown represent the volumetric flow rate (qvsglGu), A-weighted sound level (LAGu), fan efficiency (ηr), impeller power (PrGu), total pressure (pFGu), and static pressure (psFGu).

[0106] Table 1

[0107]

[0108] Table 2

[0109]

[0110] The test data and performance curves show that, compared to the comparative example and the test case, under the same or similar impeller power settings, the embodiment outperforms the comparative example in terms of fan efficiency, total pressure, and A-weighted sound level. In comparison, the test case achieved an optimal fan efficiency of 60.312% at the third operating point, with a total pressure of 2445.5 Pa and an A-weighted sound level of 77.718 dB; while the comparative example achieved an optimal fan efficiency of 55.349% at the third operating point, with a total pressure of 2242.0 Pa and an A-weighted sound level of 87.701 dB. The test case generally exhibits higher total pressure and efficiency, and lower fan noise than the comparative example.

[0111] Meanwhile, with the same or similar impeller power, in the test example, during the stable operation of the fan at operating points 2-5, the fan efficiency ranged from 55.307% to 60.312%, the total pressure ranged from 2145.2 Pa to 2512.3 Pa, and the A-weighted sound level ranged from 76.675 dB to 80.123 dB. In the comparative example, during the stable operation of the fan at operating points 2-5, the fan efficiency ranged from 52.694% to 55.349%, the total pressure ranged from 2042.8 Pa to 2309.4 Pa, and the A-weighted sound level ranged from 86.6586 dB to 90.114 dB.

[0112] The results above show that the high-efficiency, low-noise medium-pressure centrifugal fan of the present invention has higher pressure, higher efficiency, and lower noise.

[0113] Where there is no conflict, the above embodiments and features can be combined with each other.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A high-efficiency, low-noise medium-pressure centrifugal fan, comprising a volute, an impeller, and a collector, wherein the impeller is disposed inside the volute, and the collector is disposed outside the volute and fixedly connected to the volute; the impeller includes a rear disc, on which a plurality of blades are arranged in a circumferential array, the blades including long blades and short blades, the long blades and short blades being alternately arranged, characterized in that: The profile of the volute includes a first diffuser straight section, a volute tongue section, a first arc section, a second arc section, a third arc section, a fourth arc section, a first diffuser arc section, a second diffuser arc section, and a second diffuser straight section connected tangentially in sequence. The first diffuser straight section and the second diffuser straight section enclose and form a circular air outlet. The first diffuser arc section and the second diffuser arc section are externally tangent. The first arc section, the second arc section, the third arc section, and the fourth arc section are not concentric and their centers form a square. A rectangular coordinate system is established with the impeller center O as the origin. When the first diffuser segment is located in the fourth quadrant, the coordinates of the center O1 of the first arc segment are (12, 12), the radius R4 is 209mm-211mm, and the arc length is 155mm-158mm. The coordinates of the center O2 of the second arc segment are (-12, 12), the radius R5 is 232.8mm-235.2mm, and the arc length is 365.5mm-369.5mm. The coordinates of the center O3 of the third arc segment are (-12, -12), the radius R6 is 256.5mm-259.5mm, and the arc length is 403mm-407.5mm. The coordinates of the center O4 of the fourth arc segment are (12, -12), the radius R7 is 280.2mm-283.8mm, and the arc length is 428.5mm-433.5mm. The first diffuser segment and the second diffuser segment are parallel. The long blade includes a leading edge, a trailing edge, a first side connecting the leading edge and the trailing edge, and a second side connecting the leading edge and the trailing edge. The first side is the side away from the rear plate, and the second side is the side closer to the rear plate. The leading edge is designed with a biomimetic wave-shaped structure, and the trailing edge is parallel to the impeller hub. The thickness of the long blade decreases linearly from the leading edge to the trailing edge. The short blade includes a leading edge, a trailing edge, a first side connecting the leading edge and the trailing edge, and a second side connecting the leading edge and the trailing edge. The first side is the side away from the rear plate, and the second side is the side closer to the rear plate. The trailing edge is set as a biomimetic sawtooth structure, and the leading edge is parallel to the impeller hub. The thickness of the short blade decreases linearly from the leading edge to the trailing edge.

2. The high-efficiency, low-noise medium-pressure centrifugal fan according to claim 1, characterized in that: The diameter of the air outlet φ8 is 116mm-126mm, the length of the first diffuser straight section L16 is 49mm-51mm, the radius of the volute section R3 is 4.9mm-5.1mm and the arc length is 11mm-12mm, the radius of the first diffuser arc section R8 is 412mm-415mm and the arc length is 158mm-160mm, the radius of the second diffuser arc section R9 is 49.5mm-50.5mm and the arc length is 19mm-19.5mm, and the length of the second diffuser straight section L17 is 45.2mm-46.8mm; A tangent is drawn to the cochlear tongue segment at the point of tangency between the cochlear tongue segment and the first arc segment. The angle ∠8 between this tangent and the first diffuser straight segment is 46°-48°. The inner wall of the volute is coated with a nano-sound-absorbing coating.

3. The high-efficiency, low-noise medium-pressure centrifugal fan according to claim 2, characterized in that: The circumference diameter φ4 formed by the outermost ends of all long blades and all short blades is 360mm, the circumference diameter φ5 formed by the innermost ends of all long blades is 100mm-104mm, and the circumference diameter φ6 formed by the innermost ends of all short blades is 196mm-204mm. When installing long blades, the inlet angle ∠2 is 141°-144°, and the outlet angle ∠3 is 90.5°-91.5°. When installing short blades, the inlet angle ∠4 is 94°-96°, and the outlet angle ∠5 is 89.6°-90.4°. There are 12 long leaves and 12 short leaves.

4. The high-efficiency, low-noise medium-pressure centrifugal fan according to claim 3, characterized in that: From the leading edge to the trailing edge of the long blade, the first side of the long blade includes the arc segment and the straight segment of the long blade. On the projection surface of the rear disc, the maximum thickness t1 of the long blade arc segment is 4.8mm-5.2mm, the minimum thickness t2 is 4.0mm-4.3mm, the blade midpoint radius R2 of the long blade arc segment is 104mm-106mm and the arc length is 68mm-72mm, the minimum thickness t3 of the long blade straight segment is 2.9mm-3.1mm, and the length L3 of the long blade straight segment is 76mm-78mm. The impeller is cut along a plane passing through its central axis. In the cross-section: the width L5 of the leading edge of the long blade is 50.5mm-53.5mm, the width L6 of the trailing edge of the long blade is 34mm-36mm, the wavelength L7 of the wavy structure is 14.5mm-15.5mm, and the amplitude L8 is 1.15mm-1.25mm.

5. A high-efficiency, low-noise medium-pressure centrifugal fan according to claim 4, characterized in that: The long blades also have multiple recesses arranged in a rectangular array; The impeller is sectioned by a plane passing through its central axis. On the cross-section: The diameter of the pit φ7 is 2.9mm-3.1mm, and the depth of the pit is 0.9mm-1.1mm; With the direction perpendicular to the rear plate as the longitudinal direction and the direction parallel to the rear plate as the transverse direction, the pits are set to 18 rows in the transverse direction and 8 columns in the longitudinal direction; The distance between the centers of two adjacent dimples in each row is L12, and the distance between the centers of two adjacent dimples in each column is L13. L12 and L13 are equal and both are 3.8mm-4.2mm. The distance L15 between the center of the row of pits near the rear plate and the rear plate is 4.7mm-5.3mm, and the distance L14 between the center of the row of pits near the trailing edge of the long blade is 5.1mm-5.9mm.

6. The high-efficiency, low-noise medium-pressure centrifugal fan according to claim 5, characterized in that: From the leading edge to the trailing edge of the short blade, the short blade has a straight structure; On the projection surface of the rear disc, the maximum thickness t4 of the short blade is 4.8mm-5.2mm, the minimum thickness t5 is 2.9mm-3.1mm, and the length L4 of the short blade is 79mm-81mm. The impeller is cut along a plane passing through its central axis. In the cross-section: the width L9 of the leading edge of the short blades is 41mm-43mm, the tooth pitch L10 of the serrated structure is 6.8mm-7.2mm, and the tooth depth L11 is 2.9mm-3.1mm. Five sawtooth structures are set.

7. A high-efficiency, low-noise medium-pressure centrifugal fan according to claim 6, characterized in that: The collector includes an integrally formed connecting part and a front cover plate. A guide section is formed in the middle of the side of the front cover plate away from the impeller. The guide section includes a trumpet-shaped constriction section and a collecting ring. The collector is fixedly connected to the volute through the connecting part. The inner circumference of the trumpet-shaped opening of the constriction section forms an air inlet. The outlet of the collecting ring is circular and the inner circumference forms an air guide. The outlet of the front cover plate near the impeller is circular and the inner circumference forms an air intake. An axial clearance is provided between the collector and the impeller.

8. A high-efficiency, low-noise medium-pressure centrifugal fan according to claim 7, characterized in that: The diameter of the air inlet φ1 is 143mm-147mm, the diameter of the air guide φ2 is 127.5mm-130.5mm, and the diameter of the air exhaust φ3 is 376mm-382mm. The collector is cut along a plane passing through its central axis. In the cross-section: the radius R1 of the constriction section is 7.6mm-8.4mm and the arc length is 11.4mm-13.4mm; the vertical distance L1 between the air inlet and the air guide is 19mm-21mm; the vertical distance L2 between the air guide and the air outlet is 1.9mm-2.1mm; and the included angle ∠1 formed between the connecting part and the front cover is 8°-8.3°. The axial clearance L18 between the collector and the impeller is 13mm-14.5mm.

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