A method for regulating the rated air volume of a fan using a perforated plate, the perforated plate and the fan

Abstract

The application relates to a method for adjusting the rated air volume of a fan by using an orifice plate, wherein the orifice plate is provided with a large circular hole in the center and a plurality of small holes in the outer ring of the large circular hole. The method is based on a standardized calculation formula established according to the equivalent dynamic pressure of the rated static pressure of the fan, and the accurate total area of the orifice can be obtained through one-time calculation without repeated trial cutting, so that the consistency of batch fan detection is high; and the method can significantly reduce the axial vibration.

Description

Technical Field

[0001] This invention belongs to the technical field of fan air volume regulation, specifically relating to a method for regulating the rated air volume of a fan using an orifice plate, as well as the orifice plate and the fan. Background Technology

[0002] Scrollless centrifugal fans are widely used in central air conditioning units, cleanroom ventilation equipment, new energy heat dissipation units, industrial dust removal and air supply systems, and other fields. Before leaving the factory, the fans must complete a full set of performance verification tests, including vibration tests, winding temperature rise tests, motor input current detection, high and low temperature environment durability tests, and starting inrush current tests. These tests must be conducted at the rated flow rate, so an accurate rated flow rate adjustment fixture is essential.

[0003] Existing methods for regulating fan air volume fall into two categories: 1) Standard air chamber test bench adjustment: The pipeline resistance is adjusted to match the rated air volume by relying on the throttling damper at the air chamber outlet. However, the equipment is bulky and inconvenient to move. It can only be used in a fixed laboratory and cannot be matched with special equipment such as high and low temperature chambers and vibration test benches to carry out linkage tests. 2) Simple solid perforated plate for throttling: This method directly blocks the fan inlet, leaving only a small gap for flow restriction. The perforations lack standardized calculation logic, resulting in a chaotic arrangement. Airflow passing through the perforated plate generates strong turbulence and eddies, inducing two major defects: Turbulent airflow impacts the fan impeller, significantly aggravating the fan's axial vibration, causing the vibration amplitude to exceed the standard, distorting the vibration test data, and failing to accurately simulate the actual steady-state airflow conditions of the pipeline network. Turbulence causes uncontrollable pressure loss, poor airflow matching accuracy, requires repeated cutting and grinding of perforated plates, resulting in extremely low testing efficiency and poor consistency in batch fan testing.

[0004] Currently, the industry lacks a standardized manufacturing process for imported regulating orifice plates that can accurately match rated air volume, suppress airflow turbulence, and simultaneously solve the problem of excessive axial vibration of fans. Existing throttling tooling lacks quantitative design formulas and optimized orifice layout schemes, making it impossible to balance air volume regulation accuracy and fan operation stability, which is a pain point in the performance testing of fans at the factory. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a method for adjusting the rated air volume of a fan using an orifice plate, comprising the following steps: S1 obtains the rated parameters of the fan. The rated parameters of the fan include: rated air volume Q (unit: m³ / s). 3 / s), rated static pressure (Unit: Pa); S2 is used to calculate the average flow velocity across the orifice section of the perforated plate. The average airflow velocity v across the perforated plate cross-section is calculated using the following formula:

[0006] --Standard air density, taken as 1.2 kg / m³ at room temperature and pressure. 3 ; --Average airflow velocity across the perforated plate cross-section, m / s; --Rated static pressure on the fan nameplate, Pa; S3 calculates the total effective flow opening area of ​​the perforated plate. The theoretical total opening area A of the perforated plate is obtained using the following formula. 总 (unit: m) 2 ):

[0007] S4 perforated plate perforation structure design When drilling, make a large circular hole in the center, and make several small holes around the outer ring of the large circular hole.

[0008] Based on the above scheme, after step S3, the total actual perforation area A of the perforated plate is obtained by using the working condition correction coefficient. 实

[0009] For standard operating conditions at normal temperature, k = 0.95; for low-temperature operating conditions, air density increases, so k is taken as 0.92; for high-temperature operating conditions, k is taken as 0.98.

[0010] Based on the above scheme, the specific method of step S4 is as follows: (1) The center hole is located at the geometric center of the perforated plate and accounts for 60% to 70% of the total perforated area; (2) Set 1 to 3 concentric rings of small holes around the central hole. The size of the small holes on the same ring is completely consistent and they are evenly distributed along the 360° circumference of the large hole. The total flow area of ​​the small holes accounts for 30% to 40% of the remaining total opening area.

[0011] Based on the above scheme, the edge of the perforated plate should not have burrs or rounding, and the edge radius of any perforation should not exceed 0.004d, where d is the diameter of the hole.

[0012] The present invention also provides an orifice plate for adjusting the rated air volume of a fan, wherein the orifice plate has a large circular hole in the center, and several rings of small holes are formed around the outer edge of the large circular hole. Specifically, The center hole is located at the geometric center of the perforated plate and accounts for 60% to 70% of the total perforation area; (2) Set 1 to 3 concentric rings of small holes around the central hole. The size of the small holes on the same ring is completely consistent and they are evenly distributed along the 360° circumference of the large hole. The total flow area of ​​the small holes accounts for 30% to 40% of the total opening area.

[0013] Based on the above scheme, the theoretical total opening area A 总 (unit: m) 2 )for:

[0014]

[0015] --Standard air density, taken as 1.2 kg / m³ at room temperature and pressure. 3 ; --Average airflow velocity across the perforated plate cross-section, m / s; --Rated static pressure on the fan nameplate, Pa; Q -- Rated air volume of the fan.

[0016] Based on the above scheme, when drilling holes, the total actual drilled area A of the perforated plate is obtained by using the working condition correction coefficient. 实

[0017] For standard operating conditions at normal temperature, k = 0.95; for low-temperature operating conditions, air density increases, so k is taken as 0.92; for high-temperature operating conditions, k is taken as 0.98.

[0018] The present invention provides a fan with adjustable rated air volume, characterized in that it uses the above-mentioned perforated plate.

[0019] Based on the above scheme, the perforated plate is installed on the inside or outside of the fan inlet flange.

[0020] Based on the above scheme, the fan is a centrifugal fan without a volute, an axial flow fan, or a centrifugal fan with a volute.

[0021] The beneficial effects of this invention are: High air volume matching accuracy: A standardized calculation formula is established based on the equivalent dynamic pressure of the rated static pressure of the fan. There is no need for repeated trial cutting. The total area of ​​the opening can be accurately obtained in one calculation, and the consistency of batch fan testing is high. Significantly reduces axial vibration: The composite layered opening disperses the turbulent airflow, ensuring uniform inlet airflow velocity and eliminating local vortex impacts on the impeller. The alternating excitation force of the airflow is greatly reduced, resulting in a 40%–70% reduction in the amplitude of the fan's axial vibration. The vibration test data is accurate and valid. Wide range of applications: The tooling is small in size and can be directly installed on the inlet flange of the fan. It is suitable for various offline tests such as vibration test, high and low temperature durability, temperature rise, and starting current, and is not limited by large wind chambers. Low manufacturing cost and high versatility: The perforated plate is made of ordinary steel plate / plastic plate, the perforation layout is standardized, and the perforation size can be quickly calculated according to different fan models, making the processing difficult; Convenient testing and verification: Relying on the rated operating current of the fan as the criterion, the design of the perforated plate can be quickly verified to be qualified, without the need for high-precision real-time air volume monitoring equipment, thus reducing the investment in test hardware. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the perforated plate in Embodiment 2 of the present invention; Figure 2 This is a schematic diagram of the fan structure in Embodiment 2 of the present invention. Detailed Implementation

[0023] The terminology used in this invention, unless otherwise specified, generally has the meanings commonly understood by those skilled in the art. The invention is further described in detail below with reference to specific embodiments and data. The following embodiments are merely illustrative and are not intended to limit the scope of the invention in any way.

[0024] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the experimental materials, reagents, and chemicals used in the following embodiments can be obtained through general channels.

[0025] Example 1

[0026] This invention provides a method for adjusting the rated air volume of a fan using an orifice plate, comprising the following steps: (1) Obtain the rated parameters of the fan The rated parameters of the fan include: rated air volume Q (unit: m³ / s). 3 / s), rated static pressure (Unit: Pa); If the air volume unit is Q h (Unit: m / h), Q=Q needs to be converted first. h / 3600; (2) Solve for the average flow velocity across the orifice section of the plate. The average airflow velocity v across the perforated plate cross-section is calculated using the following formula:

[0027] --Standard air density, taken as 1.2 kg / m³ at room temperature and pressure. 3 ; --Average airflow velocity across the perforated plate cross-section, m / s; --Rated static pressure on the fan nameplate, Pa; (3) Calculate the total effective flow opening area of ​​the perforated plate. The total opening area A of the perforated plate is obtained using the following formula. 总 :

[0028] The total flow area (in meters) of all the perforations in the perforated plate. 2 ); (4) The total actual perforated area A of the perforated plate is obtained by using the working condition correction coefficient. 实

[0029] For standard operating conditions at normal temperature, k=0.95; for low temperature operating conditions, air density increases, so k=0.92; for high temperature operating conditions, k=0.98; the specific value is selected according to the fan operating conditions specified by the customer, with the default being standard operating conditions at normal temperature.

[0030] (5) Design of perforated plate opening structure Design rules for the central main circular hole The center hole is located at the geometric center of the perforated plate, accounting for 60% to 70% of the total flow area; The aperture is matched according to the total opening area to ensure that the mainstream airflow passes through the center and to avoid the airflow being deflected and impacting the impeller on one side. Outer ring layered small round holes arrangement rules One to three concentric rings of small holes are arranged around the central hole. The holes on the same ring are all the same size and are evenly distributed along the 360° circumference. The total circulation area of ​​the small holes accounts for 30% to 40% of the remaining effective circulation area; The small holes in two adjacent rings are staggered to prevent the airflow from forming a continuous longitudinal vortex. The edges of the perforated plate should not have burrs or rounding, and the radius of any perforation should not exceed 0.004d, where d is the diameter of the hole.

[0031] Traditional single-slit, randomly perforated plates concentrate and deflect airflow, causing high-speed airflow to impact one side of the impeller inlet, generating periodic alternating axial impact force and triggering axial resonance in the impeller motor assembly. The perforated structure of this invention evenly disperses the airflow into a central mainstream and an outer ring of uniform diversion, controlling the inlet cross-section velocity difference within ±5m / s, eliminating localized high-speed airflow impact, and ensuring uniform and stable axial force acting on the impeller end face. This significantly reduces alternating excitation force, suppressing excessive axial vibration of the fan from the source.

[0032] Example 2

[0033] Based on the method of Example 1, the present invention uses a volute-less centrifugal fan with the following parameters for air volume regulation.

[0034] Fan parameters: Rated air volume Q h =3600m 3 / h (i.e., Q=1m) 3 / s), rated static pressure Ps=1000Pa, normal temperature test k=0.95 1) Calculate the flow velocity at the orifice: 2) Theoretical total opening area: 3) Actual machined opening area: Opening layout (e.g.) Figure 1 (As shown): The flow area of ​​the central main circular hole is 0.0163m². 2 (Accounting for 70%), the outer ring has two staggered small holes (the first layer has evenly distributed small round holes, and the second layer has evenly distributed small round holes), with a total flow area of ​​0.007m². 2 (30%), all holes have an R2 chamfer.

[0035] The perforated plate is directly bolted to the outside of the inlet flange of the volute-less centrifugal fan, with the sealing gasket sandwiched between the flange and the perforated plate. No special tools are required for disassembly and assembly; replacing the perforated plate for a single fan takes no more than 3 minutes, making it suitable for batch production line testing. The effect after installation is as follows: Figure 2 As shown.

[0036] Verification results: The motor current deviated from the rated current by 1.2%; the axial vibration acceleration of the traditional perforated plate was 4.8 m / s². 2 This tooling has a speed of only 1.6 m / s. 2 The vibration reduction was 66.7%, and the air volume and temperature rise parameters had a 2.1% error compared to the air chamber test.

[0037] Example 3

[0038] Based on the method of Example 1, the present invention uses a high-temperature volute-less fan of a purification device with the following parameters to regulate the air volume.

[0039] Fan parameters: Rated air volume Q = 0.8 m³ / h 3 / s, rated static pressure Ps=1600Pa, test temperature 80℃, correction factor k=0.98 1) Flow velocity calculation: v = √(1600 / 0.6) ≈ 51.64 m / s 2) Theoretical opening area: 0.8 / 51.64≈0.0155m² 2 , 3) Actual processing area: 0.0152m² 2 Opening layout: The central hole occupies 65% of the flow area, with three rings of staggered small holes on the outer ring, and the material is made of 3mm aluminum alloy plate; Verification results: Current deviation 1.5%; axial vibration decreased from 5.3 m / s². 2 Reduced to 2.0 m / s 2 It reduces vibration by 62.3%, meeting the requirements for high-temperature durability vibration testing.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for adjusting the rated air volume of a fan using an orifice plate, characterized in that, Includes the following steps: S1 obtains the rated parameters of the fan. The rated parameters of the fan include: rated air volume Q (unit: m³ / s). 3 / s), rated static pressure (Unit: Pa); S2 is used to calculate the average flow velocity across the orifice section of the perforated plate. The average airflow velocity v across the perforated plate cross-section is calculated using the following formula: --Standard air density, taken as 1.2 kg / m³ at room temperature and pressure. 3 ; --Average airflow velocity across the perforated plate cross-section, m / s; --Rated static pressure on the fan nameplate, Pa; S3 calculates the total effective flow opening area of ​​the perforated plate. The theoretical total opening area A of the perforated plate is obtained using the following formula. 总 (unit: m) 2 ): S4 perforated plate perforation structure design When drilling, make a large circular hole in the center, and make several small holes around the outer ring of the large circular hole.

2. The method for adjusting the rated air volume of a fan using an open plate according to claim 1, characterized in that, After step S3, the total actual perforation area A of the perforated plate is obtained by using the working condition correction coefficient. 实 For standard operating conditions at normal temperature, k = 0.95; for low-temperature operating conditions, air density increases, so k is taken as 0.92; for high-temperature operating conditions, k is taken as 0.

98.

3. The method for adjusting the rated air volume of a fan using an open plate according to claim 1, characterized in that, The specific method for step S4 is as follows: (1) The center hole is located at the geometric center of the perforated plate and accounts for 60% to 70% of the total perforated area; (2) Set 1 to 3 concentric rings of small holes around the central hole. The size of the small holes on the same ring is completely consistent and they are evenly distributed along the 360° circumference of the large hole. The total flow area of ​​the small holes accounts for 30% to 40% of the remaining total opening area.

4. The method for adjusting the rated air volume of a fan using an open plate according to claim 3, characterized in that, The edges of the perforated plate should not have burrs or rounding, and the radius of any perforation should not exceed 0.004d, where d is the diameter of the hole.

5. An orifice plate for adjusting the rated air volume of a fan, characterized in that, The perforated plate has a large circular hole at its center, and several concentric rings of smaller holes around the outer edge of the large circular hole. Specifically... The center hole is located at the geometric center of the perforated plate and accounts for 60% to 70% of the total perforation area; (2) Set 1 to 3 concentric rings of small holes around the central hole. The size of the small holes on the same ring is completely consistent and they are evenly distributed along the 360° circumference of the large hole. The total flow area of ​​the small holes accounts for 30% to 40% of the total opening area.

6. The perforated plate for adjusting the rated air volume of a fan according to claim 5, characterized in that, The theoretical total opening area A 总 (unit: m) 2 )for: --Standard air density, taken as 1.2 kg / m³ at room temperature and pressure. 3 ; --Average airflow velocity across the perforated plate cross-section, m / s; --Rated static pressure on the fan nameplate, Pa; Q -- Rated air volume of the fan.

7. The perforated plate for adjusting the rated air volume of a fan according to claim 5, characterized in that, When drilling holes, the total actual drilled hole area A of the perforated plate is obtained using the working condition correction factor. 实 For standard operating conditions at normal temperature, k = 0.95; for low-temperature operating conditions, air density increases, so k is taken as 0.92; for high-temperature operating conditions, k is taken as 0.

98.

8. A fan with adjustable rated air volume, characterized in that, Use the perforated plate according to any one of claims 5-7.

9. The adjustable rated air volume fan according to claim 8, characterized in that, The perforated plate is installed on the inside or outside of the fan inlet flange.

10. The adjustable rated air volume fan according to claim 8, characterized in that, The fan is a centrifugal fan without a volute, an axial flow fan, or a centrifugal fan with a volute.

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