A centrifugal impeller with non-uniformly distributed splitter blades and its application

Abstract

This invention belongs to the technical field of wind turbines and discloses a centrifugal impeller with non-uniformly distributed diverter blades and its application. The centrifugal impeller includes: a wheel cover and a wheel disk arranged opposite each other; multiple main blades and multiple diverter blades disposed between the wheel disk and the wheel cover. The multiple main blades and multiple diverter blades are non-uniformly arranged along the wheel disk and their rotation direction is consistent with the rotation direction of the wheel disk during operation. The number of diverter blades is equal to the number of main blades. A diverter blade is disposed between two adjacent main blades, and the diverter blade is close to the pressure surface of the main blade. This application can effectively suppress flow separation and secondary flow at the blade trailing edge, improve outlet static pressure and efficiency, and reduce noise.

Description

Technical Field

[0001] This invention belongs to the field of wind turbine related technology, and more specifically, relates to a centrifugal impeller with non-uniformly distributed diverter blades and its application. Background Technology

[0002] Centrifugal fans, characterized by low flow rate and high pressure, are widely used in various industrial sectors, including mining, petrochemicals, building ventilation, power plants, and residential air conditioning. Their main feature is that gas enters axially, rotates through the blades, and flows radially within the impeller, converting mechanical energy into potential energy. However, due to flow phenomena such as flow separation, secondary flow, and jet-wake within the centrifugal fan's internal flow field, and the impact of the incoming gas on the impeller chassis, the internal flow losses in centrifugal fans are greater and more complex than other types of impellers. Furthermore, current centrifugal impellers exhibit significant flow losses and low operating efficiency. Summary of the Invention

[0003] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides a centrifugal impeller with non-uniformly distributed flow-diverting blades and its application, which can effectively suppress flow separation and secondary flow at the trailing edge of the blades and improve outlet static pressure and efficiency.

[0004] To achieve the above objectives, according to one aspect of the present invention, a centrifugal impeller with non-uniformly distributed diverter blades is provided. The centrifugal impeller includes: a wheel cover and a wheel disk disposed opposite to each other; a plurality of main blades and a plurality of diverter blades disposed between the wheel disk and the wheel cover, wherein the plurality of main blades and the plurality of diverter blades are non-uniformly arranged along the wheel disk and their rotation directions are consistent with the rotation direction of the wheel disk during operation; the number of diverter blades is equal to the number of main blades; a diverter blade is disposed between two adjacent main blades, and the diverter blade is close to the pressure surface of the main blade.

[0005] Preferably, the phase angle of the main blade satisfies a cosine modulation function:

[0006]

[0007] in, The phase angle ψ is non-uniformly distributed on the main blades. i The phase angle is uniformly distributed on the main blades, f1 is the adjustment amount of the main blades, and f1 = 2° to 8°.

[0008] The phase angle of the shunt blade satisfies a cosine modulation function:

[0009]

[0010] in, ψ represents the phase angle of the non-uniform distribution of the splitter blades.j f2 is the phase angle at which the splitter blades are evenly distributed, and f2 is the adjustment amount of the splitter blades, f2 = 1° to 3°.

[0011] Preferably, the chord length of the diverter blade is 0.2 to 0.6 times the chord length of the main blade; and the thickness of the diverter blade is 0.4 to 0.7 times the thickness of the main blade.

[0012] Preferably, the circumferential angle θ between the pressure surfaces of the splitter blade and the main blade is in the range of 0° to 10° at the radius where the splitter blade inlet is located.

[0013] Preferably, the ratio of the radial height of the main blade to the radial height of the splitter blade, i.e. the radial control coefficient ε, ranges from 0.75 to 0.9, where the radial height is the distance between the center point of the blade and the center of the wheel disk.

[0014] Preferably, the angle between the airfoil chord length of the splitter blade and the circumferential tangent of the wheel disk, i.e., the installation angle β, is in the range of 30° to 60°.

[0015] Preferably, the difference between the installation angle of the main blade and the installation angle of the splitter blade, i.e. the installation offset angle α, is in the range of -8° to 8°.

[0016] Preferably, the shape of the splitter blade and the main blade is airfoil-shaped.

[0017] Preferably, the number of main blades and diverter blades is 6 to 8.

[0018] According to another aspect of the invention, an application of a centrifugal impeller having non-uniformly distributed diverter blades is provided, the centrifugal impeller being used in an air conditioning ceiling unit.

[0019] In summary, compared with the prior art, the centrifugal impeller with non-uniformly distributed splitter blades and its application provided by the present invention have the following beneficial effects:

[0020] 1. Non-uniformly distributed splitting blades are set between the flow channels of the main blades, which can effectively divide the large vortex between the flow channels into multiple small vortices, effectively suppress flow separation and secondary flow at the trailing edge of the blades, effectively improve static pressure and efficiency, and reduce noise.

[0021] 2. The phase angles of both the main blades and the shunt blades satisfy the cosine modulation function, which not only disperses the acoustic energy at the blade passing frequency over a wide frequency range, but also ensures that the impeller can meet the static balance condition after modulation, without the need for additional modification or correction.

[0022] 3. Both the splitter blade and the main blade are airfoil-shaped, which has better aerodynamic performance, lower airflow resistance, higher aerodynamic efficiency, and longer service life compared to plate blades. Moreover, the chord length of the splitter blade is 0.2 to 0.6 times that of the main blade; the thickness of the splitter blade is 0.4 to 0.7 times that of the main blade. While meeting the splitting function, the weight of the impeller is reduced, thus lowering production costs.

[0023] 4. The circumferential angle, radial control coefficient, installation angle, and installation offset angle of the flow divider blade are all within a certain range, ensuring that the flow divider blade can generate a flow divider effect at the flow channel separation point while minimizing its own drag, thereby reducing the separation area and achieving a good flow divider effect. Attached Figure Description

[0024] Figure 1 It is an overall structural diagram of a centrifugal impeller with non-uniformly distributed flow divider blades;

[0025] Figure 2 It is a cross-sectional view of a centrifugal impeller with non-uniformly distributed splitter blades;

[0026] Figure 3 This is a schematic diagram of the rotation direction of a non-uniformly distributed splitter blade;

[0027] Figure 4 This is a schematic diagram of the arrangement of the splitter blades and the main blades, which have non-uniformly distributed splitter blades.

[0028] Figure 5 This is a schematic diagram of the radial height of a non-uniformly distributed splitter blade;

[0029] Figure 6A This is a schematic diagram of the flow field of a centrifugal impeller without splitter blades;

[0030] Figure 6B This is a schematic diagram of the flow field of the centrifugal impeller in Example 1;

[0031] Figure 7 This is a schematic diagram of the flow field of the centrifugal impeller in Example 2;

[0032] Figure 8 This is a schematic diagram of the flow field of the centrifugal impeller in Example 3;

[0033] Figure 9A The average total sound pressure level at four receiving points in the unsteady calculation of the scheme without splitter blades;

[0034] Figure 9B It is the average total sound pressure level at the four receiving points in the unsteady calculation of the scheme in Example 1;

[0035] Figure 9C This refers to the average total sound pressure level at the four receiving points during the unsteady calculation in Example 2.

[0036] Figure 9D It is the average total sound pressure level of the four receiving points in the unsteady calculation of the scheme in Example 3.

[0037] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0038] 1-Wheel cover; 2-Wheel disc; 3-Main blade; 4-Diverter blade. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0040] This invention provides a centrifugal impeller with non-uniformly distributed splitter blades, such as... Figure 1 and Figure 2 As shown, the centrifugal impeller includes a cover 1, a disc 2, main blades 3, and diverter blades 4.

[0041] Wheel cover 1 and wheel disc 2 are coaxially arranged relative to each other. Wheel cover 1 is annular, and wheel disc 2 has a conical protrusion at its center.

[0042] Multiple main blades 3 and multiple diverter blades 4 are arranged between the wheel 2 and the wheel cover 1. The main blades 3 and multiple diverter blades 4 are non-uniformly arranged along the wheel 2, and their rotation direction is consistent with the rotation direction of the wheel 2 during operation. Figure 3 As shown.

[0043] The number of main blades 3 and diverter blades 4 are equal, and a diverter blade 4 is disposed between two adjacent main blades 3, with the diverter blade 4 close to the pressure surface of the main blade 3. In a further preferred embodiment, the number of main blades and diverter blades is 6 to 8.

[0044] In further preferred solutions, such as Figure 4 As shown, the phase angle of the main blade 3 satisfies the cosine modulation function:

[0045]

[0046] in, The phase angle ψ is non-uniformly distributed on the main blades. i The phase angle is uniformly distributed on the main blades, f1 is the adjustment amount of the main blades, and f1 = 2° to 8°.

[0047] The phase angle of the shunt blade 4 satisfies a cosine modulation function:

[0048]

[0049] in, ψ represents the phase angle of the non-uniform distribution of the splitter blades. j f2 is the phase angle at which the splitter blades are evenly distributed, and f2 is the adjustment amount of the splitter blades, f2 = 1° to 3°.

[0050] In a further preferred embodiment, the chord length and thickness of the diverter blade 4 are obtained by reducing the main blade by a certain ratio. The chord length of the diverter blade 4 is 0.2 to 0.6 times the chord length of the main blade 3, and the thickness of the diverter blade 4 is 0.4 to 0.7 times the thickness of the main blade 3.

[0051] In a further preferred embodiment, the position parameters of the splitter blade 4 can be defined using circumferential control angle, radial control coefficient, installation offset angle, and installation angle.

[0052] The circumferential angle θ is the angle between the pressure surfaces of the splitter blade and the main blade at the radius where the splitter blade inlet is located, and its value ranges from 0° to 10°.

[0053] The radial control coefficient ε is the ratio of the radial height R1 of the main blade to the radial height R2 of the splitter blade, i.e., ε = R1 / R2, where the radial height is the distance between the center point of the blade and the center of the impeller. Figure 5 As shown.

[0054] The installation angle β is the angle between the airfoil chord of the splitter blade and the circumferential tangent of the rotor disk, and its value ranges from 30° to 60°.

[0055] The installation offset angle α is the difference between the installation angle β1 of the main blade and the installation angle β2 of the shunting blade, and its value ranges from -8° to 8°.

[0056] In a further preferred embodiment, the shape of the splitter blade and the main blade is an airfoil, and more specifically, it can be a C5 airfoil with different thickness distributions superimposed, having the same airfoil cross section along the axial direction. The pressure surface of the main blade and the suction surface of the adjacent main blade form a complete flow channel, and the splitter blade is arranged between the flow channels near the pressure surface of the main blade.

[0057] Another aspect of this application provides an application of a centrifugal impeller with non-uniformly distributed diverter blades, the centrifugal impeller being used in an air conditioning ceiling unit.

[0058] Example 1

[0059] In this example, the diameter of the backward centrifugal impeller with flaps is 477mm, the number of blades is 8, the number of split blades is 8, the adjustment range is 3°, the adjustment range is 2.5°, the circumferential control angle is 0°, the radial control coefficient is 0.80, the installation angle of the main blade is 55°, and the installation offset angle is between 3° and 3°.

[0060] Example 2

[0061] In this example, the diameter of the backward centrifugal impeller with flaps is 477mm, the number of blades is 8, the number of split blades is 8, the adjustment range is 3°, the adjustment range is 2.5°, the circumferential control angle is 5°, the radial control coefficient is 0.80, the installation angle of the main blade is 55°, and the installation offset angle is between 3°.

[0062] Example 3

[0063] In this example, the diameter of the backward centrifugal impeller with flaps is 477mm, the number of blades is 8, the number of splitter blades is 8, the adjustment range is 3°, and the adjustment range is 2.5°. The circumferential control angle is 10°, the radial control coefficient is 0.80, the installation angle of the main blade is 55°, and the installation offset angle is within 3°.

[0064] Adding a splitter blade to the existing blades increases torque, leading to higher power but a slight decrease in efficiency. Numerical simulations revealed that placing the splitter blade at the leading edge significantly reduces airflow, air pressure, and efficiency (Table 1). This is because the leading edge obstructs the airflow at the blade inlet. However, when the splitter blade is placed in the middle or trailing edge, the fan performance at maximum flow rate remains relatively unchanged, with a decrease in total pressure efficiency of approximately 2%.

[0065] No splitter blades Example 1 Example 2 Example 3 air volume <![CDATA[1464.79m 3 / h]]> <![CDATA[1382.81m 3 / h]]> <![CDATA[1457.40m 3 / h]]> <![CDATA[1464.48m 3 / h]]> Full pressure 54.13 Pa 48.35Pa 55.31Pa 54.74Pa Total pressure efficiency 56.92％ 51.8％ 54.84％ 54.71％

[0066] Table 1

[0067] according to Figure 6A and 6B It can be seen that, compared to the model without a splitter blade, the addition of a splitter blade at the leading edge in Example 1 blocked the airflow at the blade inlet, resulting in a significant reduction in the circumferential velocity of the blade; for example... Figure 7 As shown, in Example 2, when the splitter blade is placed in the middle, it has a significant splitting effect on the gas flow in the middle of the pressure surface side of the main blade, but has little effect on the flow separation at the trailing edge. Furthermore, because the splitter blade is placed in the middle, the flow separation phenomenon at the trailing edge of the splitter blade is not at the same location as the flow separation at the trailing edge of the main blade, thus effectively increasing the area of ​​flow separation. Figure 8 As shown in Example 3, when the flow divider blade is placed at the trailing edge, the flow divider effect is more obvious at the trailing edge of the main blade, which is equivalent to cutting the separation vortex at the trailing edge and improving the flow stability of the blade passage. Therefore, when the flow divider blade is placed at the leading edge, it will cause the fan performance to decrease, while when it is placed at the middle and trailing edge, it will not have much impact on the overall fan performance.

[0068] according to Figures 9A-9D In addition to unsteady calculation results, the average total sound pressure level at the four receiving points of the bladeless scheme is 44 dB (e.g., Figure 9A As shown), in Example 1, the average total sound pressure level at the four receiving points of the model with the leading edge of the splitter blade is 42.27 dB (as shown). Figure 9B As shown), it reduces the sound pressure level by 1.73 dB (3.9%) compared to the scheme without splitter blades; in Example 2, the average total sound pressure level at the four receiving points of the model with the splitter blade placed in the middle is 44.92 dB (as shown). Figure 9C As shown), the average total sound pressure level at the four receiving points in the splitter blade trailing edge placement model in Example 3 is 41.46 dB (as shown). Figure 9D As shown in the figure, it reduces the speed by 2.54 dB (5.78%) compared to the design without splitter blades.

[0069] Meanwhile, based on the performance analysis results, the placement scheme of the splitter blade trailing edge is the optimal scheme among the three schemes under this operating condition.

[0070] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A centrifugal impeller having non-uniformly distributed splitter vanes, characterized by, The centrifugal impeller comprises: Oppositely arranged wheel cover (1) and wheel disc (2); A plurality of main blades (3) and a plurality of splitter blades (4) are arranged between the wheel disc (2) and the wheel cover (1), the plurality of main blades (3) and the plurality of splitter blades (4) are arranged non-uniformly along the wheel disc (2) and have the same rotation direction as the rotation direction of the wheel disc (2) during work, the number of the splitter blades (4) is equal to the number of the main blades (3), one splitter blade (4) is arranged between two adjacent main blades (3), and the splitter blade (4) is close to the pressure surface of the main blade (3); The chord length of the splitter blade (4) is 0.2-0.6 times the chord length of the main blade (3), and the thickness of the splitter blade (4) is 0.4-0.7 times the thickness of the main blade (3); The phase angle of the main blade (3) satisfies the cosine modulation function: wherein, is a phase angle for non-uniform distribution of the main blades, is a phase angle for uniform distribution of the main blades, is a main blade adjustment amount, = 2° ~ 8°; The phase angle of the splitter blade (4) satisfies the cosine modulation function: wherein, is a phase angle for non-uniform distribution of splitter vanes, is a phase angle for uniform distribution of splitter vanes, is an adjustment amount of splitter vanes, = 1° ~ 3°.

2. The centrifugal impeller of claim 1, wherein The ratio of the radial height of the main blade to the radial height of the splitter blade, i.e. the radial control coefficient is in the range of 0.75-0.9, wherein the radial height is the distance of the blade center point to the center of the wheel disc.

3. The centrifugal impeller of claim 1, wherein The included angle between the airfoil chord length of the splitter blade and the circumferential tangent of the wheel disc, i.e. the installation angle , is in the range of 30°-60°.

4. The centrifugal impeller of claim 3, wherein The difference between the installation angle of the main blade and the installation angle of the splitter blade, i.e. the installation offset angle , is in the range of -8° to 8°.

5. The centrifugal impeller of claim 1, wherein The shapes of the splitter blade and the main blade are airfoil shapes.

6. The centrifugal impeller of claim 1, wherein The number of the main blades and the splitter blades is 6-8.

7. Use of a centrifugal impeller with non-uniformly distributed splitter blades according to any one of claims 1 to 6, characterized in that The centrifugal impeller is used for an air conditioner ceiling machine.

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