Middle and low pressure type axial flow fan impeller

Abstract

The utility model discloses a middle-low pressure type axial flow fan impeller which comprises a hub and a rotating ring which are coaxially arranged, and a plurality of blades are distributed between the hub and the rotating ring in the circumferential direction of the hub at unequal intervals. The roots of the blades are connected with the hub into a whole, and the tops of the blades are connected with the rotating ring into a whole; the front edge of the blade is further provided with a turbulator integrated with the blade, the turbulator comprises a plurality of protrusions arranged in the extending direction of the front edge, the protrusions are arranged to form a wave shape, and the wave amplitude is gradually reduced from the blade top to the blade middle. The axial flow fan impeller provided by the utility model has multiple innovations in the aspects of structure, parameters and process, the comprehensive advantages of low noise, high efficiency and long service life are realized through optimal design, and meanwhile, the convenience in the aspects of production and maintenance is also improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of axial flow fans, and in particular relates to a medium- and low-pressure axial flow fan impeller. Background Art

[0002] An axial flow fan is a device that directs air flow parallel to the fan shaft through the rotation of its impeller. Axial flow fans have a wide range of uses, including electric fans, air conditioner outdoor fans, and automotive axial flow fans. Consisting primarily of an impeller and a casing, an axial flow fan has a simple structure but very high performance requirements. As the core component of an axial flow fan, the impeller's excellent aerodynamic performance and noise performance are key factors in determining its performance. The impeller's blade arrangement, shape, and angle can directly impact its aerodynamic performance and noise levels.

[0003] However, there are some problems in the application of existing axial flow fans, mainly including the following:

[0004] 1. Noise: Axial fans are prone to generating resonance noise and flow noise caused by turbulent airflow pulsation when rotating at high speeds, especially during the interaction between the blades and the airflow. This not only affects the comfort of the operating environment but may also cause structural damage to the fan during long-term operation.

[0005] 2. Blade deformation: Under high-speed operation or high static pressure conditions, the blades are easily deformed due to vibration, which will reduce the efficiency of the fan, increase energy consumption, and affect the reliability of long-term use.

[0006] 3. Blade tip clearance problem: When the gap between the blade tip and the fan frame or guide cover is not designed properly, a gap that is too large will cause air leakage, reduce air volume and pressure; a gap that is too small will cause increased noise, increased friction, and even cause blade damage.

[0007] 4. Material Issues: The choice of blade material has a significant impact on the performance, lifespan, and resistance to high temperatures and corrosion. Existing materials may have difficulty maintaining stable performance over time in harsh environments. Utility Model Content

[0008] In order to solve the above technical problems, the utility model provides a medium-low pressure axial flow fan impeller.

[0009] The technical solutions provided by this utility model are as follows:

[0010] A medium- and low-pressure axial flow fan impeller includes a coaxially arranged hub and a rotating ring, with a plurality of blades distributed unequally around the circumference of the hub between the hub and the rotating ring; the roots of the blades are integrally connected to the hub, and the tops of the blades are integrally connected to the rotating ring; the leading edges of the blades are further provided with turbulators integral with the blades, the turbulators including a plurality of protrusions arranged along the extension direction of the leading edges, the protrusions being arranged in a wave shape, and the wave amplitude gradually decreasing from the blade tip to the middle of the blade.

[0011] Preferably, the ratio of the hub diameter to the impeller outer diameter is in the range of 0.2 to 0.625.

[0012] Preferably, the blade profile is a curved airfoil profile, which bends from the leading edge of the blade to the trailing edge of the blade; the leading edge angle of the blade is between 43 and 46.5°, the trailing edge angle of the blade is between 10 and 12°, and the ratio of the chord length of the blade to the maximum thickness of the blade is in the range of 9.0 to 9.42.

[0013] Preferably, the ratio of the axial height of the blade to the radial blade center length is 0.215.

[0014] Preferably, the inclination angle of the blade is between 149.5° and 164.3°, and the inclination angle increases from 149.5° at the root of the blade to 164.3° at the top of the blade.

[0015] Preferably, the blade adopts a spanwise variable load design, the load gradually increases from the blade root to the blade top, the blade chord length increases from L1 at the blade root to L2 at the blade top, and L1 / L2≈0.85.

[0016] Preferably, the angle between the leading edge of the blade and the hub at the blade root is 99.1°, and the angle between the leading edge and the rotating ring at the top of the blade is 104.5°; the angle between the trailing edge of the blade and the hub at the blade root is 82.2°, and the angle between the trailing edge and the rotating ring at the top of the blade is 117.5°.

[0017] Preferably, the ratio of the impeller diameter to the diameter of the circle where the leading edge is located is 0.57, the ratio of the impeller diameter to the diameter of the circle where the trailing edge is located is 0.33, the center P2 of the circle where the leading edge is located, the center P3 of the circle where the trailing edge is located, and the center point P1 of the impeller form a line segment L, and P1P2 / L=0.64, P2P3 / L=0.36.

[0018] Preferably, the impeller is composed of 9 identical blades distributed at unequal intervals, and the angles between the 9 blades are 34.73°, 39.29°, 44.18°, 35.9°, 44.18°, 39.29°, 34.73°, 43.85°, and 43.85°, respectively.

[0019] Preferably, the blade is divided into 15 segments along its span direction and is stacked by gravity to form a complete blade profile, and the stacking angles from the root of the blade to the top of the blade are 32.3°, 31.2°, 29.9°, 28.6°, 27.3°, 26.0°, 25.0°, 23.6°, 22.8°, 21.2°, 20.7°, 18.9°, 18.6°, 16.6°, and 16.4° respectively.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] The present invention significantly improves the performance of the impeller through a number of innovative designs. First, the blades are distributed with unequal spacing, which reduces the same-frequency resonance and vibration noise. At the same time, the wavy blade structure further reduces the aerodynamic noise under high static pressure. The optimized design of the leading and trailing chords makes the airflow smoother and reduces energy loss. The span-wise variable load design ensures the stability of the blades under different pressure conditions and reduces the deformation of the blades under high static pressure. The segmented design and the center of gravity stacking method not only improve the overall aerodynamic performance of the impeller, but also enhance the structural strength and durability of the blades, effectively avoiding fracture or deformation caused by stress concentration. The reasonable blade tip clearance design controls airflow leakage, which not only maintains the efficiency of the fan but also reduces noise and friction problems. The present invention can maintain high efficiency and save energy in a wide range of static pressure. In addition, this design not only improves the overall performance and reliability of the fan, but also makes it easy to manufacture and maintain during the production process, reduces operating costs, and has broad application prospects and customization potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention.

[0023] Figure 1 This is a schematic diagram of the structure of an axial flow fan impeller provided by an embodiment of the present utility model;

[0024] Figure 2 This is a front view of an axial flow fan impeller provided by an embodiment of the present utility model;

[0025] Figure 3 This is a cross-sectional view of a blade provided by an embodiment of the present utility model;

[0026] Figure 4 This is a schematic diagram of the axial height of a blade provided by an embodiment of the present utility model;

[0027] Figure 5 This is a schematic diagram of the center length of radial blades provided by an embodiment of the present utility model;

[0028] Figure 6 This is a schematic diagram of the blade inclination angle at the blade tip provided by an embodiment of the present utility model;

[0029] Figure 7 This is a schematic diagram of the blade inclination angle at the blade root provided by an embodiment of the present utility model;

[0030] Figure 8 This is a schematic diagram of the angle settings of the leading edge and the trailing edge provided by an embodiment of the present utility model;

[0031] Figure 9 This is a schematic diagram of the leading edge and trailing edge scale settings provided by an embodiment of the present invention;

[0032] Figure 10 It is a schematic diagram of blade center of gravity stacking molding provided by an embodiment of the present utility model. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0034] This embodiment provides a medium-low pressure axial flow fan impeller, such as Figure 1 As shown, the impeller includes a coaxially arranged hub 1 and a rotating ring 3. A plurality of blades 2 are unequally spaced around the circumference of the hub between the hub 1 and the rotating ring 3. The hub 1 is integrally connected to the blade root (blade root), and the blade tip (blade tip) is integrally connected to the rotating ring 3. One side of the blade 2 is the leading edge (the front end of the blade, the part that the airflow first contacts), and the other side is the trailing edge (the rear end of the blade, the part where the airflow leaves the blade). The leading edge is provided with a turbulator 4 integral with the blade 2. The turbulator 4 includes a plurality of protrusions arranged along the extension direction of the leading edge. The arrangement of the protrusions forms a wave shape, and the wave amplitude gradually decreases from the blade tip to the middle of the blade. The main purpose is to reduce the flow noise generated by turbulent vibration during blade rotation. The axial flow fan provided in this embodiment has an operating static pressure range of between 0 and 300 Pa and 300 and 1000 Pa, making it a medium-low pressure axial flow fan; the speed range is between 0 and 5000 rpm, and the diameter range is between 225 and 750 mm.

[0035] The hub ratio of an axial flow fan impeller refers to the ratio of the hub diameter to the outer diameter of the impeller. It is an important structural parameter that affects the pressure, flow rate, and efficiency of the fan. When the pressure, flow rate, and speed of the fan are constant, the hub ratio cannot be selected arbitrarily. A suitable hub ratio is a key factor in the design of an axial flow impeller. It needs to meet certain air volume and pressure requirements while also ensuring that the impeller has sufficient strength. Figure 2 As shown, the hub ratio of the impeller provided in this embodiment is D1 / D2=0.2~0.625. The hub ratio can float within this range and can meet the requirements of its air volume and efficiency, thereby increasing the versatility of this fan impeller, so that it can match motors with different outer diameters.

[0036] like Figure 3 As shown, the blade cross-sectional parameters of the impeller provided in this embodiment are as follows: the leading edge angle is between 43° and 46.5°, the trailing edge angle is between 10° and 12°, and the ratio of the chord length L to the maximum thickness E is in the range of 9.0 to 9.42. By meeting the above three basic parameters, the designed impeller can achieve an excellent air volume level. The blade profile of the impeller blade of this embodiment is a curved airfoil type, which bends from the leading edge to the trailing edge of the blade, and the bending angle gradually changes from 43° to 46.5° at the beginning to 10° to 12° at the end. After analysis and research, the impeller using this blade profile has higher efficiency and lower noise level. When the blades rotate, the leading edge of the impeller cuts the fluid, and the airflow gradually diverges backward from the leading edge of the impeller along the upper curved surface of the blade; the higher leading edge can withstand higher wind pressure, and the lower trailing edge can suppress the aerodynamic noise generated by high wind pressure. The smooth curve transition in the middle avoids the sudden change from high to low pressure on the blade, which causes obvious deformation of the impeller, and has a certain protective effect on the structural strength of the impeller under high wind pressure.

[0037] like Figure 4 and Figure 5 As shown, the ratio of the blade's axial height H1 to its radial center length H2 is: H1 / H2 = 0.215. This embodiment has a larger blade height and length, significantly improving the impeller's aerodynamic performance. This larger ratio can increase the fluid's velocity and pressure, significantly improving the impeller's efficiency.

[0038] like Figure 6 and Figure 7 As shown in the figure, the blade pitch angle of an axial fan ranges from 149.5° to 164.3°, increasing from 149.5° at the blade root to 164.3° at the tip. Impellers with larger blade pitch angles have better aerodynamic performance under high static pressure, as the blades can provide a greater pressure differential, significantly increasing the fan's air volume and pressure.

[0039] In this embodiment, the blades adopt a spanwise variable load design, with the load gradually increasing from the root to the tip. The blade chord length increases from L1 at the root to L2 at the tip, with the ratio being approximately: L1 / L2 = 0.85. As the impeller blades rotate, the pressure distribution on the blade surface gradually increases from the root to the tip, and the isobars can be approximated as ellipses. Therefore, the impeller adopts a spanwise variable load design, with the blade chord length gradually increasing from the root to the tip. This can effectively support the varying loads experienced at different blade locations during rotation, significantly improving blade deformation, especially under high static pressure.

[0040] The shape and design of the leading edge of the blade have a significant impact on the entry and initial acceleration of the airflow. Generally speaking, the design of the leading edge will consider reducing the resistance and separation of the airflow to improve the efficiency and performance of the fan. The shape and design of the trailing edge have an impact on the outflow of the airflow and the formation of the wake. Reasonable trailing edge design can reduce the energy loss of the wake and improve the efficiency of the fan. Figure 8 and Figure 9 As shown, in this embodiment, the leading edge forms an angle of 99.1° with the hub at the blade root, and a 104.5° angle with the rotating ring at the blade tip. The trailing edge forms an angle of 82.2° with the hub at the blade root, and a 117.5° angle with the rotating ring at the blade tip. The ratio of the impeller diameter D1 to the diameter of the circle containing the leading edge is D1 / D2 = 0.57, and the ratio of the impeller diameter D1 to the diameter of the circle containing the trailing edge is D1 / D3 = 0.33. The centers P2 and P3 of these two circles, along with the impeller center point P1, form a line segment L, with distances P1P2 / L = 0.64 and P2P3 / L = 0.36.

[0041] The tip clearance of an axial fan impeller is the radial distance between the blade tip and the fan frame or shroud. A reasonable tip clearance has a significant impact on axial fan performance. Excessive tip clearance can reduce fan efficiency. This is because a larger tip clearance increases leakage flow at the blade tip, which means air leaks at the blade tip, reducing tip pressure, lowering both air volume and pressure, and thus reducing the impeller's ability to process gas. Leakage flow refers to the flow of gas through the tip clearance between the pressure and suction sides of the blades. This flow not only reduces the main flow but also increases energy losses. Excessively small tip clearance reduces leakage flow. While this reduces leakage losses, it also increases air velocity and pressure in the blade tip area, increasing friction between the airflow at the blade tip and the fan frame or shroud. This, in turn, increases operating noise and reduces overall fan efficiency. Too little tip clearance will change the pressure distribution at the top of the impeller, potentially causing an increase in pressure on the pressure surface, leading to deformation of the blade tips and ultimately causing deformation and damage to the fan blades, thus affecting the fan's pressure performance. Too little tip clearance will affect the flow characteristics in the tip area, such as the interaction between leakage flow and mainstream flow, which may produce more vortices and backflow phenomena, thus affecting the fan's operating stability and noise level. In some specific applications, such as cooling systems, too little tip clearance may affect the conduction and dissipation of heat, resulting in reduced system efficiency. Too little tip clearance may also increase the likelihood of contact between the impeller and the shroud or casing, thereby increasing the risk of mechanical wear and failure. In addition, too little tip clearance will bring difficulties to the production and processing of the fan, because smaller tip spacing means higher processing and assembly accuracy is required, which in turn increases production costs and causes unnecessary waste. In this embodiment, the tip clearance of the impeller is less than or equal to 0.8% to 1% of the impeller diameter. The tip clearance within this range is a relatively reasonable value. The tip clearance needs to be adjusted according to the material of the air guide cover. The deformation amount, that is, the structural strength, of the air guide covers made of plastic and aluminum alloy are different, so the clearance needs to be adjusted to a reasonable value.

[0042] The fan impeller blades provided in this embodiment are distributed in an unequally spaced design. The blades are spaced at different angles around the circumference of the hub. The geometric turning angle of the blades decreases from 26.5° at the root to 10.8° at the tip. With the axial direction as a reference, the blade installation angle decreases from 32.3° at the root to 16.4° at the tip. The impeller is composed of 9 identical blades distributed in an unequally spaced manner. The angles between the 9 blades are 34.73°, 39.29°, 44.18°, 35.9°, 44.18°, 39.29°, 34.73°, 43.85°, and 43.85°, respectively. This design can more effectively guide the airflow, making the airflow inside the fan more uniform and stable, reducing airflow turbulence and vortices, thereby improving the overall performance and efficiency of the fan. This design can also enhance pressure characteristics and can adjust the pressure distribution of different parts in a targeted manner according to actual needs. For example, in areas where higher pressure is required, a specific asymmetric angle design is used to increase pressure output and meet the pressure requirements under specific working conditions. The blades are distributed at unequal intervals to solve the problem of frequency resonance generated by each blade when the impeller rotates. This can reduce vibration noise while also improving the aerodynamic performance of the fan and the efficiency of the impeller. The unequal distribution of the impeller effectively reduces the frequency at which the impeller passes through a certain point during rotation. When the impeller rotates, the fluid flows through the impeller surface, generating dynamic friction with the impeller surface. Since the impeller is distributed at unequal intervals, the friction frequency between a certain point on the impeller and the airflow at that point is reduced.

[0043] like Figure 10 As shown, the impeller blades in this embodiment adopt a segmented design, and a complete blade profile is formed by gravity stacking. Specifically, the blades are divided into 15 segments along the span direction, and a complete blade profile is formed by gravity stacking. The stacking angles from root to top are 32.3°, 31.2°, 29.9°, 28.6°, 27.3°, 26.0°, 25.0°, 23.6°, 22.8°, 21.2°, 20.7°, 18.9°, 18.6°, 16.6°, and 16.4°, respectively. This design has the following advantages:

[0044] 1. It effectively reduces the fracture damage of the impeller from the inside out due to stress concentration during the demoulding process and rotation, avoiding irreversible damage; at the same time, it also improves the carrying capacity of the impeller, making the axial flow fan impeller more stable when working in a high-load environment and improving its own strength.

[0045] 2. The stacking of different centers of gravity to form a complete blade can reduce the unbalanced force on the blade when the impeller is working; when the impeller rotates, the magnitude of the force on each part of the blade is different, and the direction of the force will be transferred to different centers of gravity, thereby improving the stability of the impeller and reducing the vibration caused by the unbalanced force on the impeller, thereby reducing vibration noise.

[0046] 3. Reasonable distribution of the impeller's center of gravity can improve the aerodynamic performance of the impeller blades, and can generate higher air volume and higher wind pressure under the same motor output torque;

[0047] 4. At the same time, this design can also reduce the fatigue strength of the blades, avoiding fatigue deformation of the impeller due to concentrated force under long-term operation, and ensuring the stable and reliable performance of the impeller during its life cycle.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Under the idea of ​​the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the present invention as described above. For the sake of simplicity, they are not provided in detail. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of this application.

Claims

1. A medium and low pressure axial flow fan impeller, characterized in that: It includes a coaxially arranged hub and a rotating ring, with a number of blades distributed unequally around the circumference of the hub between the hub and the rotating ring; the roots of the blades are connected to the hub as a whole, and the tops of the blades are connected to the rotating ring as a whole; the leading edges of the blades are also provided with turbulators integrated with the blades, which include a plurality of protrusions arranged along the extension direction of the leading edge, the arrangement of the protrusions forms a wave shape, and the wave amplitude gradually decreases from the blade top to the middle of the blade.

2. A medium-low pressure axial flow fan impeller according to claim 1, characterized in that: The ratio of the hub diameter to the impeller outer diameter ranges from 0.2 to 0.

625.

3. A medium-low pressure axial flow fan impeller according to claim 1, characterized in that: The blade shape is a curved airfoil shape, which bends from the leading edge to the trailing edge of the blade; the leading edge angle of the blade is between 43 and 46.5 degrees, the trailing edge angle of the blade is between 10 and 12 degrees, and the ratio of the chord length of the blade to the maximum thickness of the blade is in the range of 9.0 to 9.

42.

4. A medium-low pressure axial flow fan impeller according to claim 1, characterized in that: The ratio of the axial height of the blade to the radial blade center length is 0.

215.

5. The medium-low pressure axial flow fan impeller according to claim 1, characterized in that: The inclination angle of the blade is between 149.5° and 164.3°, and the inclination angle increases from 149.5° at the root of the blade to 164.3° at the top of the blade.

6. The medium-low pressure axial flow fan impeller according to claim 1, characterized in that: The blade adopts a span-wise variable load design, where the load gradually increases from the blade root to the blade top, the blade chord length increases from L1 at the blade root to L2 at the blade top, and L1 / L2≈0.

85.

7. The medium-low pressure axial flow fan impeller according to claim 1, characterized in that: The leading edge of the blade has an angle of 99.1° with the hub at the blade root, and an angle of 104.5° with the rotating ring at the blade top; the trailing edge of the blade has an angle of 82.2° with the hub at the blade root, and an angle of 117.5° with the rotating ring at the blade top.

8. The medium-low pressure axial flow fan impeller according to claim 1, characterized in that: The ratio of the impeller diameter to the diameter of the circle where the leading edge is located is 0.57, the ratio of the impeller diameter to the diameter of the circle where the trailing edge is located is 0.33, the center P2 of the circle where the leading edge is located, the center P3 of the circle where the trailing edge is located, and the center point P1 of the impeller form a line segment L, and P1P2 / L=0.64, P2P3 / L=0.

36.

9. The medium-low pressure axial flow fan impeller according to claim 1, characterized in that: The impeller is composed of 9 identical blades distributed at unequal intervals, and the angles between the 9 blades are 34.73°, 39.29°, 44.18°, 35.9°, 44.18°, 39.29°, 34.73°, 43.85°, and 43.85°, respectively.

10. The medium-low pressure axial flow fan impeller according to claim 1, characterized in that: The blade is divided into 15 sections along its span direction and is stacked by gravity to form a complete blade profile, and the stacking angles from the root of the blade to the top of the blade are 32.3°, 31.2°, 29.9°, 28.6°, 27.3°, 26.0°, 25.0°, 23.6°, 22.8°, 21.2°, 20.7°, 18.9°, 18.6°, 16.6° and 16.4° respectively.

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