Conical arc-shaped blade and centrifugal impeller

Abstract

The invention discloses a conical arc-shaped blade and a centrifugal impeller. The conical arc-shaped blade comprises blade bodies, and the multiple blade bodies are arranged between a front disc and a rear disc which are coaxially arranged in an annular array mode; the radius of the conical arc surface of the blade body is gradually increased from the side close to the rear disc to the side close to the front disc in the height direction of the blade body. The blade bodies are conical arc-shaped, so that included angles are formed between the blades and the front disc as well as between the blades and the rear disc, the front edges of the blades can meet vortex clusters which are formed in the impeller rotating process in advance, formation of the vortex clusters is destroyed, the vortex clusters are scattered and reduced, and therefore vortex losses are reduced; therefore, vortex noise is reduced, noise generated by airflow disturbance is reduced, meanwhile, inlet vortex loss is reduced, energy loss generated when airflow passes through the impeller can be reduced, pressure distribution on the surfaces of the blades becomes more uniform, the pressure difference between the pressure faces and the suction faces of the blades is reduced, and then the static pressure efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of centrifugal impeller noise reduction, and in particular to a conical arc blade and a centrifugal impeller. Background Art

[0002] EMUs have many advantages, such as large transport capacity, convenient boarding and alighting, safety and reliability, energy saving and environmental protection, etc., and have been widely used in recent years. Since EMUs run between cities, in order to reduce the impact of vehicle noise on surrounding residents, EMUs have strict noise requirements for major components. A large number of centrifugal fans are used in the cooling process of EMU traction transformers, traction converters and traction motors, and centrifugal fans are the main source of noise.

[0003] At present, there are two main noise reduction measures for centrifugal fans on EMUs: one is the passive noise reduction measure of noise reduction cotton, and the other is the active noise reduction measure of bionic serrated blades at the blade outlet. Due to the limited installation space of centrifugal fans on EMUs, it is difficult to implement passive noise reduction measures such as noise reduction and silencing materials. In addition, there are complex environments such as high dust, catkins, rain and snow on the EMU running lines. The maintenance of noise reduction and silencing materials is poor, and the noise reduction effect will decrease after a period of use. In the prior art, the wake noise is reduced by adding a serrated bionic structure at the outlet of the centrifugal fan blade, but this solution will reduce the pressure and efficiency of the fan to a certain extent while reducing the noise. Summary of the invention

[0004] The present invention provides a conical arc blade and a centrifugal impeller to solve the above problems.

[0005] In order to achieve the above object, the technical solution of the present invention is:

[0006] In one aspect, the present invention provides a conical arc blade, comprising a blade body, wherein a plurality of blade bodies are arranged in an annular array between a front disk and a rear disk coaxially arranged, wherein the top of the blade body is fixedly connected to the front disk, and the bottom of the blade body is fixedly connected to the rear disk;

[0007] The blade body is in a conical arc shape, and the radius of the conical arc surface of the blade body gradually increases from the side close to the rear disc to the side close to the front disc along the height direction thereof.

[0008] Furthermore, the cone angle of the blade body is a, and the range of a is 8° to 12°.

[0009] Furthermore, the central angle corresponding to the arc length of the blade body is θ, and the range of θ is 30° to 40°.

[0010] Furthermore, the radius of the arc edge at the connection between the blade body and the rear disc is R, and the range of R is 200mm-300mm.

[0011] Furthermore, one end of the blade body close to its centerline is the gas inlet, and the other end away from its centerline is the gas outlet. The inlet is set on a circle with a center on the centerline of the rear disk or the front disk and a diameter of D 1 The outlet is located on the circumference of a circle with a center on the center line of the rear disc or the front disc and a radius of D 2 The diameter of the rear disc is D 3 , D 1 =(0.5~0.6)D 3 , D 2 =(0.85~0.95)D 3 .

[0012] Another aspect of the present invention provides a centrifugal impeller, comprising the aforementioned conical arc blades, a front disk and a rear disk.

[0013] Furthermore, the front disc is in a conical arc shape, and the rear disc is in a flat disc or a conical arc shape.

[0014] Furthermore, a concave slot is provided on the rear disc, and the shape of the concave slot is adapted to the shape of the convex plug at the bottom of the blade body.

[0015] The beneficial effects of the present invention are:

[0016] A conical arc blade disclosed in the present invention makes the blade body into a conical arc shape so that there is an angle between the blade and the front disk and the rear disk, which can ensure that the leading edge of the blade will encounter the vortex group being formed during the rotation of the impeller in advance, destroy the formation of the vortex group, and make the vortex group be broken up and smaller, thereby reducing the vortex loss, and then achieving the reduction of vortex noise and the reduction of noise caused by airflow disturbance. At the same time, the reduction of the inlet vortex loss can also reduce the energy loss of the airflow when passing through the impeller, make the pressure distribution on the blade surface more uniform, reduce the pressure difference between the pressure surface and the suction surface of the blade, and thus improve the static pressure efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 This is a front view of a blade body of a conical arc blade disclosed in the first embodiment of the present invention (the convex plug is not shown);

[0019] Figure 2 A top view of a blade body of a conical arc blade disclosed in Embodiment 1 of the present invention;

[0020] Figure 3 It is a structural schematic diagram of a centrifugal impeller disclosed in the second embodiment of the present invention;

[0021] Figure 4 It is a front view of a centrifugal impeller disclosed in the second embodiment of the present invention;

[0022] Figure 5 for Figure 4 Cross-sectional view along the AA direction.

[0023] In the figure: 1. Blade body; 2. Front disc; 3. Rear disc. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 described embodiments 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Embodiment 1:

[0026] like Figure 1-2 The present embodiment shows a conical arc blade, comprising a blade body 1, wherein a plurality of blade bodies are arranged in a circular array between a front disk 2 and a rear disk 3 which are coaxially arranged, wherein the top of the blade body is fixedly connected to the front disk, and the bottom of the blade body is fixedly connected to the rear disk;

[0027] The blade body is in a conical arc shape, and the radius of the conical arc surface of the blade body gradually increases from the side close to the rear disc 3 to the side close to the front disc 2 along the height direction thereof.

[0028] A conical arc blade disclosed in the present invention makes the blade body into a conical arc shape so that there is a certain angle between the blade and the front disk and the rear disk, which can ensure that the leading edge of the blade will encounter the vortex group being formed during the rotation of the impeller in advance, destroy the formation of the vortex group, and make the vortex group be broken up and smaller, thereby reducing the vortex loss, and then achieving the reduction of vortex noise and the noise generated by airflow disturbance. At the same time, the reduction of the inlet vortex loss can also reduce the energy loss of the airflow when passing through the impeller, make the pressure distribution on the blade surface more uniform, reduce the pressure difference between the pressure surface and the suction surface of the blade, and then improve the static pressure efficiency.

[0029] When the impeller is working, the airflow will enter the impeller. Under the action of the impeller's rotation, a vortex group will gradually form at the entrance of the blade. The formation of the vortex group will increase the disturbance and energy loss of the airflow, and will also generate vortex noise. The energy loss will lead to a reduction in the kinetic energy of the fluid, thereby affecting the pressure distribution of the fluid and ultimately affecting the static pressure efficiency. Since the conical blades are inclined in the direction of rotation, the inclined leading edge of the blades will encounter the vortex group that is being formed in advance, destroying the formation of the vortex group, breaking up the vortex group and making it smaller, reducing the vortex loss, and thus achieving a reduction in vortex noise and an improvement in static pressure efficiency. Especially for low-speed and low-pressure fans, the main source of noise is vortex noise. Reducing vortex noise can reduce fan noise. Reducing the inlet vortex loss will also reduce the pressure difference between the pressure surface and the suction surface of the blade, and the static pressure will be improved to a certain extent, thereby improving the static pressure efficiency.

[0030] Preferably, the cone angle of the blade body is a, and the range of a is 8°~12°; the cone angle is the angle between the generatrix on the conical surface (conical surface of the frustum part) of the blade body and its center line OO (axis line). Compared with a non-conical arc blade with no angle between its center line, that is, a non-inclined blade, the present blade is set to between 8°~12°, which can enable the leading edge of the blade to encounter the vortex group that is being formed in advance, destroy the formation of the vortex group, reduce the loss of the vortex and reduce the pressure difference between the pressure surface and the suction surface of the blade body, thereby achieving the reduction of vortex noise and the improvement of static pressure efficiency.

[0031] Preferably, the central angle corresponding to the arc length of the blade body is θ, and the range of θ is 30° to 40°; the central angle θ set in the range is matched with the range of the cone angle a of the blade body, so that the blade can effectively reduce the eddy loss and thus improve the pressure distribution on the blade surface, making it more uniform, thereby helping to reduce the energy loss of the airflow when passing through the impeller, and maintain the kinetic energy of the airflow, ultimately improving the static pressure efficiency, while achieving effective noise reduction.

[0032] Preferably, the radius of the arc edge at the connection between the blade body and the rear disk is R, and the range of R is 200mm-300mm; by setting the radius size and coordinating with the center angle θ and cone angle a of the blade body, the leading edge of the blade can further change the flow direction of the airflow, thereby destroying the formation of vortex groups, breaking up the vortex groups and making them smaller. By breaking up the vortex groups, vortex losses are reduced, and the energy loss of the airflow through the impeller is reduced, so that the pressure difference between the pressure surface and the suction surface of the blade becomes smaller, thereby helping to improve the static pressure efficiency of the fan and reduce the generation of vortex noise. That is, through the shape and size design of the blades of the present application, the noise reduction and static pressure efficiency improvement of the fan can be achieved.

[0033] Preferably, the end of the blade body close to its centerline is the gas inlet, and the end away from its centerline is the gas outlet. The inlet is set on a circle with a center on the centerline of the rear disk or the front disk and a diameter of D 1 The outlet is located on the circumference of a circle with a center on the center line of the rear disc or the front disc and a radius of D 2 The diameter of the rear disc is D 3 , D 1 =(0.5~0.6)D 3 , D 2 =(0.85~0.95)D 3 The rear disk diameter is the outer diameter of the impeller. The position of the blade body in the front disk and the rear disk is ensured by setting the inlet and outlet positions of the blade body, so that the setting position of the blade body matches the specific size of the blade body, further ensuring the effective reduction of eddy current noise and the effective improvement of static pressure efficiency.

[0034] Preferably, the bottom of each cone arc generatrix on the pressure surface of the blade body is arranged on the circumference of a circle with a diameter D, and the diameter D 1 <D<D 2 .

[0035] Embodiment 2:

[0036] A centrifugal impeller, such as Figure 3-5 As shown, it includes the conical arc blade, the front disk 2 and the rear disk 3.

[0037] Preferably, the front disc 2 is in a conical arc shape, and the rear disc 2 is in a flat disc or a conical arc shape. The conical arc-shaped front disc can more effectively guide the airflow into the impeller, reduce the turbulence and resistance of the airflow at the inlet, and make the airflow more evenly distributed in the flow channel of the impeller, so as to improve the overall efficiency of the fan; the flat disc rear disc is convenient for the installation of the blade body and simplifies the structure; in actual use, the specific types of the front disc and the rear disc can be selected and set according to requirements.

[0038] Preferably, the rear disc is provided with a concave slot, the shape of which is adapted to the shape of the convex plug at the bottom of the blade body. When assembling the impeller, first insert the plug of the blade body into the concave slot to complete the positioning of one end of the blade body, then place the front disc on the upper side of the blade body, and position it by positioning tooling to ensure the coaxiality of the front disc and the rear disc, and finally weld and fix the blade body to the front disc and the rear disc;

[0039] In this embodiment, the specific parameters of the impeller and the blade body are as follows:

[0040] D 3 Take 360, D 1 Take 197.2, D 2Take 317.6, the center angle θ takes 33.3°, the cone angle a takes 10°, the radius of the arc edge (bottom arc radius) R at the connection between the blade body and the rear disk takes 212.5, and according to D 1 , D 2 , θ and R, determine that the diameter D of the circle where the bottom of the cone arc generatrix on the pressure surface of the blade body (the center point of the cone arc) is located is 245.6;

[0041] It has been verified through experiments that the static pressure efficiency of the fan using the centrifugal impeller is 63.7%, and the noise is 78.3dB(A). The static pressure efficiency of the fan whose existing blades are not set with a cone angle is 59%, and the noise is 82.5dB(A). The static pressure efficiency of the fan using the blades in this application is increased by 4.7%, and the noise is reduced by 4.2dB(A), which proves that the blades and centrifugal impellers can achieve effective noise reduction and improve static pressure efficiency.

[0042] 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. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A conical arc blade, characterized in that: It comprises a blade body (1), wherein a plurality of blade bodies are arranged in an annular array between a front disk (2) and a rear disk (3) which are coaxially arranged, wherein the top of the blade body is fixedly connected to the front disk, and the bottom of the blade body is fixedly connected to the rear disk; The blade body is in a conical arc shape, and the radius of the conical arc surface of the blade body gradually increases along its height direction from the side close to the rear disc (3) to the side close to the front disc (2).

2. The conical arc blade according to claim 1, characterized in that: The cone angle of the blade body (1) is a, and the range of a is 8° to 12°.

3. The conical arc blade according to claim 2, characterized in that: The arc length of the blade body (1) corresponds to a central angle θ, and the range of θ is 30° to 40°.

4. The conical arc blade according to claim 3, characterized in that: The radius of the arc edge at the connection between the blade body (1) and the rear disc (3) is R, and the range of R is 200mm-300mm.

5. The conical arc blade according to claim 4, characterized in that: The end of the blade body (1) close to its centerline is a gas inlet, and the end away from its centerline is a gas outlet. The inlet is arranged on the circumference of a circle with a center located on the centerline of the rear disk or the front disk and a diameter of D1. The outlet is arranged on the circumference of a circle with a center located on the centerline of the rear disk or the front disk and a radius of D2. The diameter of the rear disk is D3, D1 = (0.5-0.6)D3, D2 = (0.85-0.95)D3.

6. A centrifugal impeller, characterized in that: It comprises a conical arc blade as described in any one of claims 1 to 5, a front disk (2) and a rear disk (3).

7. A centrifugal impeller according to claim 6, characterized in that: The front disc (2) is in a conical arc shape, and the rear disc (3) is in a flat disc or a conical arc shape.

8. A centrifugal impeller according to claim 6, characterized in that: The rear disc (3) is provided with a concave slot, the shape of which is adapted to the shape of the convex plug at the bottom of the blade body (1).

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