A high specific speed centrifugal fan impeller

Abstract

The application belongs to the technical field of ventilator impellers, and discloses a high specific speed centrifugal ventilator impeller, which comprises a mounting disc, one end outer surface of the mounting disc is fixedly provided with an air inlet cylinder, and the other end of the mounting disc is fixedly provided with a center wheel disc, the outer surface of the mounting disc is provided with an air inlet channel, the outer surface of the center wheel disc is fixedly provided with blades, and the blades are integrally made of nanometer composite materials. The high specific speed centrifugal ventilator impeller is characterized in that the blades are designed in an arc shape, the inner concave side is provided with a flow guide groove and an arc concave angle, and the blades are designed in a variable cross-section, and the cross-section area decreases according to a specific exponential function law, which makes the airflow flow more smoothly on the surface of the blades, effectively reduces the thickness of the airflow boundary layer, reduces the flow resistance, reduces the airflow impact loss, optimizes the airflow flow state, and further significantly improves the energy conversion efficiency. Compared with the traditional impeller, the ventilator can realize greater air volume output under the same power consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fan impellers, in particular to a high specific speed centrifugal fan impeller. BACKGROUND

[0002] In modern industrial production and various engineering applications, centrifugal fans as an important fluid conveying equipment are widely used in ventilation, air conditioning, pneumatic conveying and gas compression in industrial production and many other fields. With the continuous progress and development of industrial technology, the performance requirements of centrifugal fans are increasingly stringent, especially the performance under high specific speed conditions, which has become a key indicator to measure their advantages and disadvantages. Traditional centrifugal fan impellers have many limitations in design and performance, and it is difficult to meet the growing demand for high performance. For example, in the blade design, the traditional impeller blades usually adopt a simple geometric shape, which leads to flow separation, boundary layer thickening and other phenomena when the airflow flows on the blade surface, thereby producing large flow resistance and energy loss, making the energy conversion efficiency of the fan low. At the same time, due to the poor flow state of the airflow on the blade surface, it also causes strong airflow pulsation and noise, which adversely affects the operation stability of the equipment and the working environment.

[0003] From the overall structure of the impeller, the adaptability of the traditional design to different working conditions is poor. When the operating conditions of the centrifugal fan change, such as changes in flow rate, pressure and other parameters, the traditional impeller is difficult to work efficiently and stably, and is prone to problems such as a significant drop in efficiency and surging, which limits the application range of the fan under complex working conditions. In addition, under high speed operation conditions, the high heat generated by the high speed rotation of the impeller cannot be effectively dissipated, which not only affects the material properties of the impeller, reduces its strength and service life, but also may cause equipment failure and safety hazards.

[0004] In order to improve the performance of centrifugal fans, the prior art has made some improvement attempts in impeller design, such as adjusting the number and shape of the blades. However, these improvements are often only partial optimization and do not fundamentally solve the above problems. Moreover, some improvement measures increase the manufacturing difficulty and cost of the impeller to some extent, but do not bring matching performance improvement. Therefore, it is of great practical significance and urgent market demand to develop a centrifugal fan impeller that has high energy conversion efficiency, good airflow flow characteristics, adapts to different operating conditions and has effective heat dissipation function under high specific speed conditions, in order to improve the overall performance of the centrifugal fan, reduce energy consumption and expand the application field. SUMMARY

[0005] The present application aims to provide a high specific speed centrifugal fan impeller to solve the problems of low energy conversion efficiency, poor airflow flow state, poor working condition adaptability and poor heat dissipation of the conventional centrifugal fan impeller.

[0006] To achieve the above object, the present application provides the following technical solution: a high specific speed centrifugal fan impeller, comprising a mounting disc, one end of the mounting disc is fixedly provided with an air inlet cylinder on the outer surface, and the other end of the mounting disc is fixedly provided with a center wheel disc, the outer surface of the mounting disc is provided with an air inlet channel, the inner side surface of the center wheel disc is provided with an air outlet channel, the outer side surface of the center wheel disc is fixedly provided with blades, and the blades are integrally made of a nano composite material.

[0007] Preferably, the blades are arc-shaped, the inner concave side surface of the blades is provided with a flow guide groove, and the groove bottom of the flow guide groove is provided with an arc concave angle, the blades adopt a variable cross-section design, the cross-sectional area from the radial outer side root of the blades to the blade tip on the radial inner side decreases according to an exponential function law, and the coefficient of the exponential function is in the range of 0.8-1.2, so as to optimize the airflow flow state on the blade surface and improve the energy conversion efficiency.

[0008] By adopting the above technical solution, the arc-shaped blades cooperate with the flow guide groove and the arc concave angle to make the airflow flow path on the blade surface more reasonable, and the variable cross-section design can optimize the airflow characteristics at different positions, so as to realize efficient airflow and improve the energy conversion efficiency.

[0009] Preferably, the blades are provided with a hollow cavity, and the two ends of the hollow cavity are open, the number of the blades is between 12-20, the number of the blades on the mounting disc with a diameter less than 500mm is 12-16, and the number of the blades on the mounting disc with a diameter greater than 500mm is 16-20, so as to realize efficient operation of the impeller under different working conditions.

[0010] By adopting the above technical solution, different numbers of blades are arranged according to the diameter of the mounting disc, the flow and pressure characteristics of the impeller can be changed, the impeller can maintain high efficiency under different working conditions, and the demand of various application scenarios can be met.

[0011] Preferably, the outer side surface of the center wheel disc is fixedly provided with a turbulence column, the turbulence column is in a water drop shape, the end with a larger diameter of the turbulence column is arranged towards the air outlet channel, the turbulence columns are uniformly distributed on one side of the air outlet channel, the height of the turbulence column is 1%-3% of the radius of the impeller, and the maximum diameter of the turbulence column is 0.5-1 times the height of the turbulence column, the airflow near the wheel disc is disturbed by the turbulence column, the airflow distribution is improved, and the generation of secondary flow is inhibited.

[0012] The special shape and distribution of the water-drop-shaped turbulence column can effectively disturb the airflow near the wheel disc, break the flow state that may generate secondary flow, improve the airflow distribution, and improve the overall performance and operation stability of the ventilator.

[0013] Preferably, the hollow cavity is internally fixedly provided with heat exchange plates, and the outer surfaces of the opposite sides of the two heat exchange plates are fixedly provided with heat exchange protrusions, the protrusion height of the heat exchange protrusions being 5%-10% of the spacing between the two heat exchange plates, so that the heat exchange effect of the cooling medium and the wall surface of the heat exchange plates is enhanced through the heat exchange protrusions, and the cooling efficiency is improved.

[0014] The above technical scheme increases the flow path of the cooling medium through the S-shaped heat exchange plates, increases the heat exchange area through the heat exchange protrusions, and adjusts the flow rate of the cooling medium through the change of the cross-sectional area of the channel, so that the heat of the impeller is efficiently taken away under the combined action, and the material performance of the impeller is guaranteed.

[0015] Preferably, the one end of the center wheel disc is fixedly provided with a connecting joint, and the inside of the center wheel disc is provided with a communication groove.

[0016] The above technical scheme facilitates the connection of the impeller and other components through the connecting joint, and the communication groove can be used to realize the flow of the medium, so as to ensure the stable operation of the impeller in the entire ventilation system.

[0017] Preferably, the groove depth of the flow guide groove is 0.1-0.3mm, the width of the flow guide groove is 0.2-0.5mm, the spacing between adjacent flow guide grooves is 0.5-1.0mm, and the flow guide groove is designed in a continuous S shape, so as to reduce the thickness of the boundary layer of the airflow to reduce the flow resistance.

[0018] The above technical scheme can effectively change the boundary layer characteristics of the airflow on the blade surface through the flow guide groove with specific size and shape, and the continuous S-shaped design further enhances the drag reduction effect and reduces the energy loss of the airflow on the blade surface.

[0019] Preferably, the round corner radius of the arc concave corner at one end of the root of the flow guide groove is 5%-10% of the width of the blade root, and the round corner radius of the arc concave corner at one end of the blade tip of the flow guide groove is 8%-12% of the width of the blade tip, so as to reduce the impact loss of the airflow and improve the operation stability of the impeller.

[0020] The above technical scheme can effectively alleviate the impact of the airflow when the airflow flows through the root and the blade tip of the flow guide groove through the arc concave corner with a specific round corner radius at different positions, reduce the energy loss, and ensure the stable operation of the impeller.

[0021] Preferably, the heat exchange plates are continuously S-shaped, and the two heat exchange plates are closed at one end away from the central wheel disc, the spacing between the two ends of the two heat exchange plates is different, and the cross-sectional area of the channel between the two heat exchange plates gradually decreases from the inlet to the outlet, and the cross-sectional area of the channel at both ends decreases by 15-25%, by passing in the cooling medium, the temperature of the impeller is reduced when running at high speed, and the material performance of the impeller is ensured.

[0022] By adopting the above technical scheme, the S-shaped heat exchange plate cooperates with the change of the cross-sectional area of the channel, which can promote the cooling medium to fully exchange heat with the heat exchange plate during flow, improve the cooling efficiency, and maintain the normal temperature of the impeller during high-speed operation.

[0023] Preferably, the outer surface of the blade is coated with a coating layer having a drag reduction and wear resistance, and the thickness of the coating layer on the outer surface of the blade is 0.05-0.1mm, the coating layer on the outer surface of the blade is composed of nano ceramic particles and high polymer polymer, and the volume fraction of the nano ceramic particles in the coating layer is 30%-50%, so as to prolong the service life of the impeller, and further reduce the airflow resistance.

[0024] By adopting the above technical scheme, the coating layer composed of nano ceramic particles and high polymer polymer has the characteristics of reducing resistance and wear resistance, which can reduce the airflow resistance, resist airflow erosion and wear, and prolong the service life of the impeller.

[0025] Compared with the prior art, the high specific speed centrifugal fan impeller of the application has the following advantages:

[0026] 1. The blade is designed in an arc shape, the inner concave side is provided with a flow guide groove and an arc concave angle, and the variable cross-section design is adopted, and the cross-sectional area decreases according to a specific exponential function, which makes the airflow flow more smoothly on the surface of the blade, effectively reduces the thickness of the airflow boundary layer, reduces the flow resistance, reduces the airflow impact loss, optimizes the airflow flow state, and further significantly improves the energy conversion efficiency. Compared with the traditional impeller, the fan can realize larger air volume output under the same power consumption.

[0027] 2. According to the different diameters of the mounting disc, the number of blades is reasonably set between 12-20, which makes the impeller can run efficiently under different working conditions, whether it is small flow high pressure or large flow low pressure working condition demand, it can realize good performance through the adaptation of the number of blades, greatly expand the application range of centrifugal fan, and improve the adaptability of the equipment to complex working conditions.

[0028] 3. Water drop-shaped turbulence columns are arranged outside the central wheel disc, the larger diameter end of the water drop-shaped turbulence columns faces the air outlet, and the water drop-shaped turbulence columns are uniformly distributed, the turbulence columns can effectively disturb the airflow near the wheel disc, improve the airflow distribution condition, inhibit the generation of secondary flow, make the airflow in the ventilator more stable and orderly, reduce the energy loss caused by airflow turbulence, and further improve the overall performance and operation stability of the ventilator.

[0029] 4. The S-shaped heat exchange plates and heat exchange protrusions are arranged in the hollow cavity inside the blade, and the cross-sectional area of the heat exchange plate channel gradually decreases from the inlet to the outlet, by passing the cooling medium, the heat generated by the impeller during high-speed operation can be efficiently taken away, the temperature of the impeller is reduced, the material performance of the impeller is effectively guaranteed, problems such as material strength reduction and deformation caused by high temperature are avoided, the service life of the impeller is prolonged, and long-term stable and reliable operation of the ventilator at high speed is ensured.

[0030] 5. The outer surface of the blade is coated with a coating composed of nano ceramic particles and high molecular polymer, which has drag reduction and wear resistance. This not only further reduces airflow resistance and improves ventilation efficiency, but also effectively resists airflow erosion and wear, greatly prolongs the service life of the impeller, reduces equipment maintenance and replacement costs, and improves the economy and reliability of the equipment. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall three-dimensional structure of the present application.

[0032] Figure 2 It is a schematic diagram of the three-dimensional structure of the connection between the mounting disc and the air inlet cylinder of the present application.

[0033] Figure 3 It is a schematic diagram of the three-dimensional structure of the connection between the central wheel disc and the air outlet of the present application.

[0034] Figure 4 It is a schematic diagram of the three-dimensional structure of the connection between the central wheel disc, the air outlet and the turbulence column of the present application.

[0035] Figure 5 It is a schematic diagram of the three-dimensional structure of the connection between the blade, the flow guide groove and the arc recess angle of the present application.

[0036] Figure 6 It is a schematic diagram of the three-dimensional structure of the connection between the hollow cavity, the heat exchange plate and the heat exchange protrusion of the present application.

[0037] Figure 7 It is a schematic diagram of the three-dimensional structure of the connection between the blade, the flow guide groove and the arc recess angle of the present application.

[0038] In the figure: 1, mounting disc; 2, air inlet cylinder; 3, center wheel disc; 4, air inlet; 5, air outlet; 6, blade; 7, guide groove; 8, arc concave corner; 9, hollow cavity; 10, turbulence column; 11, heat exchange plate; 12, heat exchange protrusion; 13, connecting joint; 14, communication groove. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0040] Please refer to Figures 1-7 The present application provides a technical solution: a high specific speed centrifugal fan impeller, comprising a mounting disc 1, one end of the mounting disc 1 is fixedly provided with an air inlet cylinder 2 on the outer surface, and the other end of the mounting disc 1 is fixedly provided with a center wheel disc 3, the outer surface of the mounting disc 1 is provided with an air inlet 4, the inner surface of the side surface of the center wheel disc 3 is provided with an air outlet 5, the outer surface of the center wheel disc 3 is fixedly provided with a blade 6, and the blade 6 is integrally made of a nano composite material;

[0041] The blade 6 is designed in an arc shape, the inner concave side of the blade 6 is provided with a guide groove 7 on the outer surface, and the groove bottom of the guide groove 7 is provided with an arc concave corner 8, the blade 6 adopts a variable cross-section design, the cross-sectional area from the mirror image outer side root of the blade 6 to the blade tip of the mirror image inner side of the blade 6 decreases according to an exponential function law, and the coefficient of the exponential function is in the range of 0.8-1.2, so as to optimize the flow state of the air flow on the surface of the blade 6 and improve the energy conversion efficiency;

[0042] The inside of the blade 6 is provided with a hollow cavity 9, and both ends of the hollow cavity 9 are designed as openings, the number of the blade 6 is between 12-20, the number of the blade 6 on the mounting disc 1 with a diameter less than 500mm is 12-16, and the number of the blade 6 on the mounting disc 1 with a diameter greater than 500mm is 16-20, so as to realize high-efficiency operation of the impeller under different working conditions;

[0043] The outer surface of the center wheel disc 3 is fixedly provided with a turbulence column 10, the turbulence column 10 is designed in a water drop shape, the larger-diameter end of the turbulence column 10 is arranged towards the air outlet 5, and the turbulence column 10 is uniformly distributed on one side of the air outlet 5, the height of the turbulence column 10 is 1%-3% of the radius of the impeller, and the maximum diameter of the turbulence column 10 is 0.5-1 times the height of the turbulence column 10, the air flow near the wheel disc is disturbed by the turbulence column, the air flow distribution is improved, and the generation of secondary flow is inhibited;

[0044] The groove depth of the flow guide groove 7 is 0.1-0.3mm, the width of the flow guide groove 7 is 0.2-0.5mm, the spacing between adjacent flow guide grooves 7 is 0.5-1.0mm, the flow guide groove 7 is designed in a continuous S shape to reduce the thickness of the air flow boundary layer and reduce the flow resistance;

[0045] The fillet radius of the arc fillet 8 at one end of the root of the flow guide groove 7 is 5%-10% of the width of the root of the blade 6, and the fillet radius of the arc fillet 8 at one end of the tip of the flow guide groove 7 is 8%-12% of the width of the tip of the blade 6, to reduce air flow impact loss and improve the operating stability of the impeller;

[0046] The outer surface of the blade 6 is coated with a coating layer with drag reduction and wear resistance, and the coating thickness of the outer surface of the blade 6 is 0.05-0.1mm, the outer surface of the blade 6 is coated with a coating layer composed of nano ceramic particles and high molecular polymer, and the volume fraction of the coating nano ceramic particles is 30%-50%, to prolong the service life of the impeller and further reduce the air flow resistance;

[0047] The hollow cavity 9 is fixedly provided with heat exchange plates 11, and the outer surfaces of the opposite sides of the two heat exchange plates 11 are fixedly provided with heat exchange protrusions 12, the protrusion height of the heat exchange protrusion 12 is 5%-10% of the spacing between the two heat exchange plates 11, the heat exchange effect of the cooling medium and the wall surface of the heat exchange plate 11 is enhanced by the heat exchange protrusion 12, and the cooling efficiency is improved;

[0048] A connecting joint 13 is fixedly installed at one end of the center wheel disc 3, and a communication groove 14 is formed in the center wheel disc 3;

[0049] The heat exchange plates 11 are designed in a continuous S shape, and the ends of the two heat exchange plates 11 away from the center wheel disc 3 are designed in a closed manner, the spacing between the two ends of the two heat exchange plates 11 is different, the cross-sectional area of the passage between the two heat exchange plates 11 gradually decreases from the inlet to the outlet, and the reduction ratio of the cross-sectional area of the passage at both ends is 15%-25%, by passing in the cooling medium, the temperature of the impeller during high-speed operation is reduced, and the material performance of the impeller is ensured.

[0050] Example one: application of nano composite material

[0051] Moment of inertia calculation:

[0052] The mass of the traditional aluminum alloy impeller is known as m1=50kg, and the radius is r=0.3m, according to the formula of moment of inertia , the moment of inertia of the traditional aluminum alloy impeller is .

[0053] The density of the new carbon nanotube reinforced aluminum alloy nano composite material impeller is reduced by 25%, so the mass of the new carbon nanotube reinforced aluminum alloy nano composite material impeller is .

[0054] The moment of inertia of the new carbon nanotube reinforced aluminum alloy nano composite material impeller is .

[0055] Example 2: Variable cross-section blade 6 design

[0056] Exponential function determination:

[0057] Based on Bernoulli equation , the pressure p and flow velocity v distribution of the blade surface airflow under different exponential function coefficients were simulated by CFD software.

[0058] Taking the energy conversion efficiency as the optimization goal, the objective function .

[0059] Assuming that the input power is P in =100kW, the output power under different exponential function coefficients is obtained by simulation as follows:

[0060]

[0061] After multiple simulation calculations, when the exponential function coefficient is 1.0, Obj reaches the maximum value, at which time the flow rate, pressure and energy conversion efficiency of the compressor reach a good balance.

[0062] Example 3: Microstructure groove setting

[0063] Boundary layer thickness calculation:

[0064] According to the boundary layer theory, the thickness of the flat plate laminar boundary layer is (v is the kinematic viscosity, x is the distance from the leading edge of the plate, and v is the incoming flow velocity).

[0065] Let the kinematic viscosity of air be , the incoming flow velocity v=30m / s, and the distance from the leading edge of the plate x=0.2m.

[0066] The boundary layer thickness before setting the microstructure groove is .

[0067] After setting, the airflow velocity distribution near the groove is measured by a hot-wire anemometer, and the boundary layer thickness is calculated by combining the theoretical formula , so , i.e. the boundary layer thickness is reduced by 30%.

[0068] Example 4: Turbulence column 10 setting

[0069] Secondary flow suppression effect evaluation:

[0070] The PIV technology is used to measure the flow field velocity distribution near the wheel disc, and the secondary flow intensity parameter is defined as the velocity component perpendicular to the main flow direction, is the average velocity of the main flow).

[0071] Before setting the spoiler column 10, the measured data are , and the calculated data are .

[0072] After setting the spoiler column 10, the measured data are , and it is found that , which indicates that the secondary flow is effectively suppressed.

[0073] Example Five: Transition Treatment of Inlet and Outlet Fillets

[0074] Impact loss calculation:

[0075] According to the impact theory, the impact loss coefficient , the pressure loss caused by impact, is the fluid density, and v is the flow rate.

[0076] Let the air density be .

[0077] The pressure sensor is used to measure the pressure at the inlet and outlet of the impeller, and the impact loss coefficient before setting the fillet is calculated as .

[0078] After setting, .

[0079] After calculation, , i.e. the impact loss is reduced by 15%.

[0080] Example Six: Cooling Channel Design

[0081] Channel cross-sectional area change calculation:

[0082] According to the law of conservation of mass is the cooling medium density, v is the flow rate, and A is the channel cross-sectional area.

[0083] The cooling medium is water, which is incompressible, .

[0084] To ensure that the cooling medium maintains a suitable flow rate in the channel, the outlet flow rate (determined according to experience and cooling requirements), and the inlet flow rate , the inlet channel cross-sectional area , i.e. the channel cross-sectional area decreases by 20% from the inlet to the outlet.

[0085] Example Seven: Setting of Cooling Channel Protruding Structure

[0086] Heat exchange coefficient calculation:

[0087] According to Newton's cooling formula , the experimental temperature difference of the cooling medium at the inlet and outlet , the heat flow density q, the heat exchange coefficient h1 before the convex structure is set and h2 after the convex structure is set.

[0088] Assuming that the heat flow density q before the convex structure is set , the temperature difference of the cooling medium at the inlet and outlet .

[0089] After the convex structure is set, .

[0090] After calculation, , that is, the heat exchange coefficient is increased by 25%.

[0091] Example eight: coating coating

[0092] Wear degree evaluation:

[0093] The wear degree of the surface of the blade 6 is measured by the weight loss method, and the wear mass of the uncoated blade 6 is , and the wear mass of the coated blade 6 is .

[0094] The wear degree ratio , that is, the wear degree of the surface of the blade 6 is reduced by 60% compared with the uncoated blade 6.

[0095] Example nine: optimization of the number of blades 6

[0096] The number of blades 6 is selected according to:

[0097] According to the cascade theory, the number of blades 6 Z is related to the impeller diameter D, the flow coefficient ψ, the pressure coefficient and other parameters.

[0098] For a small centrifugal fan (diameter D=400mm=0.4m), assuming that the flow rate , the total pressure p=1000Pa, through theoretical calculation and empirical formula (t is the blade pitch, , and is related to the flow coefficient and the pressure coefficient), combined with the flow coefficient , the pressure coefficient=1.2, the number of blades Z=14 is finally calculated.

[0099] For a large centrifugal fan (diameter D=600mm=0.6m), assuming that the flow rate , the total pressure p=1500Pa, and the number of blades Z=18 is determined by calculation.

[0100] The above specific embodiments further illustrate the purpose, technical scheme and beneficial effects of the present application, and it should be understood that the above are only specific embodiments of the present application and do not limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application is included in the protection scope of the present application.

Claims

1. A high specific speed centrifugal fan impeller comprising a mounting disc (1), an air inlet cylinder (2) is fixedly arranged on the outer surface of one end of the mounting disc (1), and a center wheel disc (3) is fixedly arranged on the other end of the mounting disc (1), characterized in that: The outer surface of the installation disc (1) is provided with an air inlet channel (4), the inner surface of the side surface of the center wheel disc (3) is provided with an air outlet channel (5), and the outer surface of the center wheel disc (3) is fixedly provided with a blade (6), and the blade (6) is integrally formed by a nano composite material. The outer surface of the center wheel disc (3) is fixedly provided with a spoiler column (10), the spoiler column (10) is designed in a water drop shape, one end of the spoiler column (10) with a larger diameter is arranged towards the air outlet channel (5), and the spoiler column (10) is uniformly distributed on one side of the air outlet channel (5), the height of the spoiler column (10) is 1%-3% of the radius of the impeller, and the maximum diameter of the spoiler column (10) is 0.5-1 times of the height of the spoiler column, the spoiler column (10) disturbs the airflow near the wheel disc, improves the airflow distribution, and suppresses the generation of secondary flow.

2. A high specific speed centrifugal fan impeller according to claim 1, characterized in that: The blade (6) is designed in an arc shape, the inner concave side of the blade (6) is provided with a flow guide groove (7), and the groove bottom of the flow guide groove (7) is provided with an arc concave corner (8), the blade (6) is designed in a variable cross-section, the cross-sectional area of the blade (6) from the radial outer side root to the blade tip on the radial inner side decreases according to an exponential function, and the coefficient of the exponential function is 0.8-1.2, so as to optimize the flow state of the airflow on the surface of the blade (6) and improve the energy conversion efficiency.

3. A high specific speed centrifugal fan impeller according to claim 1, characterized in that: The inner part of the blade (6) is provided with a hollow cavity (9), and both ends of the hollow cavity (9) are designed in an open type, the number of the blade (6) is between 12-20, the number of the blade (6) on the installation disc (1) with a diameter less than 500mm is 12-16, and the number of the blade (6) on the installation disc (1) with a diameter greater than 500mm is 16-20, so as to realize the high-efficiency operation of the impeller under different working conditions.

4. A high specific speed centrifugal fan impeller according to claim 3, characterised in that: The inner part of the hollow cavity (9) is fixedly provided with a heat exchange plate (11), and the outer surface of the opposite side of the two heat exchange plates (11) is fixedly provided with a heat exchange protrusion (12), the protrusion height of the heat exchange protrusion (12) is 5%-10% of the distance between the two heat exchange plates (11), the heat exchange effect of the cooling medium and the wall surface of the heat exchange plate (11) is enhanced by the heat exchange protrusion (12), and the cooling efficiency is improved.

5. A high specific speed centrifugal fan impeller according to claim 1, characterized in that: One end of the center wheel disc (3) is fixedly provided with a connecting joint (13), and the inner part of the center wheel disc (3) is provided with a communication groove (14).

6. A high specific speed centrifugal fan impeller according to claim 2, characterized in that: The groove depth of the flow guide groove (7) is 0.1-0.3mm, the width of the flow guide groove (7) is 0.2-0.5mm, the distance between the adjacent flow guide grooves (7) is 0.5-1.0mm, and the flow guide groove (7) is designed in a continuous S type, so as to reduce the thickness of the airflow boundary layer and reduce the flow resistance.

7. A high specific speed centrifugal fan impeller according to claim 2, characterized in that: The corner radius of one end of the arc concave corner (8) at the root of the flow guide groove (7) is 5%-10% of the width of the blade (6) root, and the corner radius of one end of the arc concave corner (8) at the blade tip of the flow guide groove (7) is 8%-12% of the width of the blade (6) blade tip, so as to reduce the airflow impact loss and improve the operation stability of the impeller.

8. A high specific speed centrifugal fan impeller according to claim 4, characterized in that: The heat exchange plate (11) is designed in a continuous S shape, two heat exchange plates (11) are closed at one end away from the center wheel disc (3), the distance between the two ends of the two heat exchange plates (11) is different, the cross-sectional area of the channel between the two heat exchange plates (11) gradually decreases from the inlet to the outlet, and the reduction ratio of the cross-sectional area of the channel at both ends is 15%-25%, by passing in the cooling medium, the temperature of the impeller during high-speed operation is reduced, and the material performance of the impeller is ensured.

9. A high specific speed centrifugal fan impeller according to claim 1, characterized in that: The outer surface of the blade (6) is coated with a coating layer with drag reduction and wear resistance, and the thickness of the coating layer on the outer surface of the blade (6) is 0.05-0.1mm, the coating layer on the outer surface of the blade (6) is composed of nano ceramic particles and high polymer polymer, and the volume fraction of the coating layer nano ceramic particles is 30%-50%, to prolong the service life of the impeller, and further reduce the air flow resistance.

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