A flat-plate type fan impeller and its design method

Abstract

The present application discloses a flat-plate type fan impeller and its design method, which belongs to the field of fans. It includes a front disk, a rear disk and a plurality of main blades. The front disk and the rear disk are straight structures, and the main blades are welded and fixedly connected to the front disk and the rear disk respectively. A sub-blade is arranged on one side of the pressure-bearing surface of the main blade, and the sub-blade is detachably connected to the main blade through a connecting piece. The beneficial effect of the present application is to provide a flat-plate type fan impeller with a simplified structure, low manufacturing difficulty and short maintenance time and its design method.

Description

Technical Field

[0001] The present application relates to the technical field of fans, and in particular to a flat disc fan impeller and a design method thereof. Background Art

[0002] As gas conveying equipment, fans are widely used in various fields of the national economy. During the use of fans in various fields, the manufacturing process of fans is relatively complicated because the front disk of the impeller mostly adopts an arc-shaped front disk or a conical impeller front disk. In particular, large fan impellers with an arc-shaped front disk require large-scale spinning equipment, which is complex to manufacture and has a long manufacturing period.

[0003] At the same time, in the actual use of the fan, long-term operation of the fan and the presence of special gases such as dust will cause wear of the impeller blades, affecting the normal operation of the fan. When replacing the fan, the entire rotor needs to be replaced, which has a long replacement cycle and long downtime, affecting the normal production of users. How to simplify the impeller structure and manufacturing difficulty and reduce maintenance time has become an urgent problem to be solved in the fan industry. Summary of the invention

[0004] The content of this application is used to introduce concepts in a brief form, which will be described in detail in the detailed implementation section below. The content of this application is not intended to identify the key features or essential features of the technical solution claimed for protection, nor is it intended to limit the scope of the technical solution claimed for protection.

[0005] In order to solve the technical problems mentioned in the above background technology part, some embodiments of the present application provide a flat disc fan impeller, including a front disc, a rear disc and a plurality of main blades, the front disc and the rear disc are flat structures, and the main blades are welded and fixedly connected to the front disc and the rear disc respectively; a sub-blade is provided on one side of the pressure surface of the main blade, and the sub-blade is detachably connected to the main blade through a connecting piece.

[0006] The present invention also discloses a design method for a flat disc fan impeller, comprising the following steps:

[0007] a. Calculate the effective diameter D2 of the impeller outlet, the impeller and blade inlet diameters D0 and D1, the blade inlet height b1, and select the blade inlet angle β b1 , select the blade outlet angle β b2 , calculate the blade outlet width value b2 and the number of blades Z;

[0008] b. Calculate and check the ω1 / ω2 value to determine whether it meets the preset ω1 / ω2;

[0009] c. Check the air volume and pressure to determine whether they meet the design requirements;

[0010] d. Compile the calculation EXCEL, mark and classify the input value column and the process formula column, adjust the blade inlet and outlet angle parameters to make b1 and b2 basically equal, and output the impeller parameters;

[0011] e. According to the output impeller parameters, conduct 3D modeling and CFD analysis, check the design results. If the design requirements are met, output the final design scheme; if not, adjust the design parameters according to the calculated performance parameters and flow field information until the design requirements are met.

[0012] Furthermore, the calculation formula for D2 in step a is as follows:

[0013] D2 = 60 * U2 / n / π;

[0014] Where n s = 5.54n(Q / 3600)^0.5 / (1.2 * P / ρ)^0.75; (According to the calculated n s , check Figure 3 - Specific speed n s vs. pressure coefficient ψ relationship diagram, select the ψ value)

[0015] U2 = (2P / ρ / ψ)^0.5;

[0016] Where Q is the input fan flow rate (unit: m 3 / h), P is the wind pressure (unit: Pa), n is the fan speed (unit: rpm), ρ is the gas medium density (unit: kg / m 3 ), ψ is the fan pressure coefficient, n s is the fan specific speed, and U2 is the impeller linear velocity (unit: m / s).

[0017] The calculation formulas for D0 and D1 in step a are as follows:

[0018] D0 = D1 = k * ((Q / 3600 / η v / n / μ0 / (1 - ν * ν))^(1 / 3));

[0019] Where k = 3.25 * ((ζ i + ζ r + ζ1 * ζ1 * ζ b ) / ζ b )^(1 / 6);

[0020] Where ζ i is the inlet loss coefficient, ζ r is the axial to radial loss coefficient, ζ b is the impeller internal loss coefficient, ζ1 is the blade inlet coefficient, ν is the hub diameter ratio, η v is the volumetric efficiency, μ0 is the air flow filling coefficient at the impeller inlet section, and k is the correction coefficient.

[0021] Further, the calculation formula of b1 in step a is as follows:

[0022] b1 = D1 / 4 * (1 - ν * ν) * μ o / ζ1 / μ1;

[0023] where μ1 is the filling coefficient of the air flow at the blade inlet.

[0024] Further, the calculation formula of Z in step a is as follows:

[0025] Z = 2.1 * σ * (D2 + D1) / (D2 - D1);

[0026] where σ is the cascade density, Z1 is the number of inlet blades, Z2 is the number of outlet blades, and Z 1、 Z2 is obtained by rounding Z calculated.

[0027] Further, the calculation formula of b2 in step a is as follows:

[0028] b2 = b1 * ω1 / ω2 * μ1 / μ2 * (π * D1 * SIN(β b1 / 180 * π) - δ * Z1) / (π * D2 * SIN(β b2 / 180

[0029] * π) - Z2 * δ);

[0030] where β b1 is the integer value of β b1' β b1' = TANH(β b1' / π * 180);

[0031] TAN(β b1' / π * 180) = C 1r’ / U1;

[0032] C 1r’ = Q / 3600 / η v / (D1 * π * b1 * μ1);

[0033] U1 = D1 / 2 * (n * π / 30);

[0034] where μ2 is the filling coefficient of the air flow at the blade outlet, δ is the blade thickness, β b1 is the blade inlet angle (degree), β b1' is the blade front inlet angle (degree), C 1r’ is the radial velocity before the blade inlet, and U1 is the impeller inlet linear velocity.

[0035] Further, in step b, preset ω1 / ω2 = 1.8, calculate and check the value of ω1 / ω2, and determine whether ω1 / ω2 ≤ 1.8 is satisfied;

[0036] Among them, the calculation formula of ω1 is as follows:

[0037] ω1 = C 1r / SIN(β b1 / 180*π);

[0038] Among them, C 1r = C 1r’ / τ1;

[0039] τ1 = 1 - δ / SIN(β b1 / 180*π) / D1 / π*Z1;

[0040] Among them, τ1 is the blockage coefficient of the blade inlet section, C 1r is the radial velocity at the blade inlet, and ω1 is the relative velocity at the blade inlet;

[0041] The calculation formula of ω2 is as follows:

[0042] ω2 = C 2r / SIN(β b2 / 180*π);

[0043] Among them, C 2r = Q / 3600 / η v / π / D2 / b2 / τ2 / μ2;

[0044] τ2 = 1 - δ / SIN(β b2 / 180*π) / D2 / π*Z2;

[0045] Among them, τ2 is the blockage coefficient of the blade outlet section, C 2r is the radial velocity at the blade outlet, and ω2 is the relative velocity at the blade outlet.

[0046] Further, the air volume check formula in step c is as follows:

[0047] Q = η v *τ1*π*D1*b1*C 1r’ *3600;

[0048] The air pressure check formula is as follows:

[0049] P = η h *μ*ρ*π^2*n^2*(D2^2 - D1^2*b2 / b1*TANβ b1 ' / TAN(β b2 / 180*π)) / 6

[0050] 0^2;

[0051] where μ = 1 / (1 + (1.5 + 1.1*β b2 / 90) / 24 / (1 - (D1 / D2) 2 ))

[0052] where η h is the flow efficiency and μ is the slip coefficient.

[0053] The beneficial effects of this application are as follows: It provides a flat - disc type fan impeller with a simplified impeller structure, low manufacturing difficulty, and short maintenance time, as well as its design method. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The drawings constituting a part of this application are used to provide a further understanding of this application, making other features, objectives, and advantages of this application more obvious. The schematic embodiments and descriptions of the drawings of this application are used to explain this application and do not constitute an improper limitation to this application.

[0055] In addition, throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic, and the elements and components are not necessarily drawn to scale.

[0056] In the drawings:

[0057] Figure 1 is the overall schematic diagram according to the embodiment of this application;

[0058] Figure 2 is the structural schematic diagram of a part of the embodiment;

[0059] Figure 3 is the relationship diagram between the specific speed n s and the pressure coefficient ψ. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0060] The embodiments of the present disclosure will be described in more detail below with reference to the drawings. Although some embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are only for exemplary purposes and are not used to limit the protection scope of the present disclosure.

[0061] In addition, it should also be noted that for the sake of convenience of description, only parts related to the relevant invention are shown in the drawings. Without conflict, the embodiments and features in the present disclosure can be combined with each other.

[0062] It should be noted that the concepts such as "first" and "second" mentioned in the present disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0063] It should be noted that the modifications of "one" and "plurality" mentioned in the present disclosure are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0064] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0065] like Figures 1-2 As shown, a flat disc fan impeller includes a front disc 4, a rear disc 5 and a plurality of main blades 2, wherein the front disc 4 and the rear disc 5 are flat structures, and the main blades 2 are welded and fixedly connected to the front disc 4 and the rear disc 5 respectively, as the main skeleton. Since the impeller front disc is flat and the blades are also flat, the problems of the complicated manufacturing process of conventional impellers and the difficulty in replacing the blades after wear can be effectively solved, and the production equipment such as the spinning machine can be omitted, and the manufacturing process is simple. A sub-blade 1 is provided on one side of the pressure surface of the main blade 2, and the pressure surface is the air inlet side. The sub-blade 1 is detachably connected to the main blade 2 through a connecting member 3, and the material can be a butt-welded wear-resistant layer blade or a special wear-resistant material blade form. In this embodiment, the connecting member 3 is riveted or bolted, and is set at multiple points, so that the connection is more secure. Preferably, the front disc 4 is set to an arc or cone corresponding to the blade inlet position, so that the airflow can be smoothly guided into the blade. When used in places with high dust concentration, the most vulnerable parts are the pressure surface inlet and outlet of the blades. After the fan has been running for a long time, when replacing the impeller, you only need to replace the blades without replacing the entire rotor. You can remove the damaged blades at the user's site, pull them out of the impeller, and install new blades, reducing maintenance time and user downtime losses.

[0066] The above-mentioned fan impeller design method comprises the following steps:

[0067] a. Calculate the effective diameter D2 of the impeller outlet, the impeller and blade inlet diameters D0 and D1, the blade inlet height b1, and select the blade inlet angle β b1 , select the blade outlet angle β b2 , calculate the blade outlet width value b2 and the number of blades Z;

[0068] b. Calculate and check the ω1 / ω2 value to determine whether it meets the preset ω1 / ω2;

[0069] c. Check the air volume and pressure to determine whether they meet the design requirements;

[0070] d. Compile the calculation EXCEL, mark and classify the input value column and the process formula column, adjust the blade inlet and outlet angle parameters to make b1 and b2 basically equal, and output the impeller parameters; the design process table of the whole machine is shown in Table 1.

[0071] e. According to the output impeller parameters, conduct 3D modeling and CFD analysis, check the design results. If the design requirements are met, output the final design scheme; if not, adjust the design parameters according to the calculated performance parameters and flow field information until the design requirements are met.

[0072] The specific operation is as follows: According to the design input, the fan flow rate Q = 12000 (unit m 3 / h), the wind pressure P = 3500 (unit Pa), the fan speed n = 1450 (unit rpm), and the gas medium density ρ = 1.2 (unit kg / m3). Select the inlet loss coefficient ζ i = 0, the axial-to-radial loss coefficient ζ r = 0.2, the impeller internal loss coefficient ζ b = 0.2, the blade inlet coefficient ζ1 = 0.85, the hub diameter ratio ν = 0.3, the volumetric efficiency η v = 0.95, the air flow filling coefficient μ at the impeller inlet section o = 1, the air flow filling coefficient μ1 at the blade inlet = 0.9, the air flow filling coefficient μ2 at the blade outlet = 0.85, the flow efficiency η h = 0.95, the blade thickness δ = 0.004m, and the cascade density σ = 1.8.

[0073] According to the formula n s = 5.54n(Q / 3600)^0.5 / (1.2*P / ρ)^0.75, calculate the fan specific speed n s , n s = 32.23. According to the calculated n S and Figure 3 , select the appropriate fan pressure coefficient ψ, and select ψ = 1.123;

[0074] According to the formula U2 = (2P / ρ / ψ)^0.5, calculate the impeller linear velocity U2 = 72m / s; and according to the formula D2 = 60*U2 / n / π; calculate D2 = 0.95m.

[0075] After that, according to the formula:

[0076] D0 = D1 = k*((Q / 3600 / η v / n / μo / (1 - ν*ν))^(1 / 3))

[0077] k = 3.25*((ζ i + ζ r + ζ1*ζ1*ζb ) / ζ b ) ^ (1 / 6)

[0078] It is calculated that D0 = D1 = 0.493 m, and the correction coefficient k = 3.558.

[0079] According to the formula: b1 = D1 / 4 * (1 - ν * ν) * μ o / ζ1 / μ1, it is calculated that b1 = 0.1466 m.

[0080] According to the calculated β b1' value, select the blade inlet angle β b1 : According to the formula:

[0081] β b1' = TANH(TANβ b1' ) / π * 180

[0082] Among them, TANβ b1' = C 1r’ / U1,

[0083] C 1r’ = Q / 3600 / η v / (D1 * π * b1 * μ1),

[0084] U1 = D1 / 2 * (n * π / 30),

[0085] β b1 ' = TANH(TANβ b1 ' ) / π * 180

[0086] Among them, C 1r’ is the radial velocity before the blade inlet, U1 is the impeller inlet line speed, and β b1' is the blade front inlet angle;

[0087] It is calculated that C 1r’ = 17.17 m / s, U1 = 37.43 m / s, TANβ b1' = 0.4587, β b1' = 24.58°.

[0088] Select the blade inlet angle β b1 = 27.8°.

[0089] According to the calculation formula: Z = 2.1 * σ * (D2 + D1) / (D2 - D1), it is calculated that Z == 11.95, and Z1 and Z2 are obtained by rounding the calculated Z. Therefore, Z1 = Z2 is taken as 12 pieces.

[0090] Select the blade outlet angle β b2= 26.5°, according to the calculation formula:

[0091] b2 = b1 * ω1 / ω2 * μ1 / μ2 * (π * D1 * SIN(β b1 / 180 * π) - δ * Z1) / (π * D2 * SIN(β b2 / 180

[0092] * π) - Z2 * δ), it is calculated that b2 = 0.14688m.

[0093] In step b, it is preset that ω1 / ω2 = 1.8,

[0094] The calculation formula of ω1 is as follows:

[0095] ω1 = C 1r / SIN(β b1 / 180 * π);

[0096] Among them, C 1r = C 1r’ / τ1;

[0097] τ1 = 1 - δ / SIN(β b1 / 180 * π) / D1 / π * Z1;

[0098] Among them, ω1 is the relative velocity at the blade inlet, C 1r is the radial velocity at the blade inlet, and τ1 is the blockage coefficient of the blade inlet section;

[0099] It is calculated that τ1 = 0.9335, C 1r = 18.39m / s, ω1 = 39.44m / s.

[0100] The calculation formula of ω2 is as follows:

[0101] ω2 = C 2r / SIN(β b2 / 180 * π);

[0102] Among them, C 2r = Q / 3600 / η v / π / D2 / b2 / τ2 / μ2;

[0103] τ2 = 1 - δ / SIN(β b2 / 180 * π) / D2 / π * Z2;

[0104] Among them, τ2 is the blockage coefficient of the blade outlet section, C 2r is the radial velocity at the blade outlet, and ω2 is the relative velocity at the blade outlet.

[0105] It is calculated that τ2 = 0.964, C 2r= 9.78 m / s, ω2 == 21.9 m / s, ω1 / ω2 = 1.8, meeting the preset requirements.

[0106] The air volume checking formula in step c is as follows:

[0107] Q = η v *τ1*π*D1*b1*C 1r’ *3600;

[0108] The air pressure checking formula is as follows:

[0109] P = η h *μ*ρ*π^2*n^2*(D2^2 - D1^2*b2 / b1*TAN(β b1 / 180*π) / TAN(β b2 / 18

[0110] 0*π)) / 60^2;

[0111] Among them, μ is the slip coefficient, μ = 1 / (1 + (1.5 + 1.1*β b2 / 90) / 24 / (1 - (D1 / D2) 2 ))

[0112] It is calculated that μ = 0.906, the air volume Q = 12447 m 3 / h, and the air pressure P = 3830 Pa.

[0113] After the operation in step d, according to the output impeller parameters, three-dimensional modeling and CFD analysis are carried out. The CFD calculation results are basically consistent with the actual prototype test results. When the air volume is 12000 m 3 / h, the pressure is 3620 Pa. This working condition has the highest efficiency, and the highest efficiency of the fan is 86.6%. The designed fan meets the requirements.

[0114] Table 1

[0115]

[0116]

[0117] The above description is only some preferred embodiments of the present disclosure and the description of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the embodiments of the present disclosure.

Claims

1. Design method of a flat-plate type fan impeller, characterized in that: It includes the following steps: a. Calculate the effective diameter D2 at the impeller outlet, the impeller and blade inlet diameters D0, D1, the blade inlet height b1, and the blade front inlet angle β b1’ , select the blade inlet angle β b1 , select the blade outlet angle β b2 , calculate the blade outlet width value b2 and the number of blades Z; b. Calculate and check the value of ω1 / ω2 to determine whether it meets the preset ω1 / ω2; c. Check the air volume and air pressure to determine whether it meets the design requirements; d. Compile a calculation EXCEL, mark and classify the input value column and the process formula column, adjust the blade inlet and outlet angle parameters to make b1 and b2 basically equal, and output the impeller parameters; e. According to the output impeller parameters, perform 3D modeling and CFD analysis to check the design results. If it meets the design requirements, output the final design scheme; if it does not meet the requirements, adjust the design parameters according to the calculated performance parameters and flow field information until it meets the design requirements. The calculation formula for D2 in step a is as follows: D2 = 60 * U2 / n / π; where n s = 5.54n(Q / 3600)^0.5 / (1.2*P / ρ)^0.75; According to the calculated ns, check Figure 3 - Relationship Diagram of Specific Speed ns and Pressure Coefficient ψ to select the value of ψ; U2 = (2P / ρ / ψ)^0.5; Among them, Q is the input fan flow rate (unit: m 3 / h), P is the wind pressure (unit: Pa), n is the fan speed (unit: rpm), ρ is the density of the gas medium (unit: kg / m 3 ), ψ is the fan pressure coefficient, n s is the specific speed of the fan, U2 is the impeller linear velocity (unit: m / s); the calculation formulas of D0 and D1 in step a are as follows: D0 = D1 = k * ((Q / 3600 / η v / n / μ0 / (1 - ν * ν)) ^ (1 / 3)); where k = 3.25 * ((ζ i + ζ r + ζ1 * ζ1 * ζ b ) / ζ b ) ^ (1 / 6); Among them, ζ i is the intake loss coefficient, ζ r is the axial-to-radial loss coefficient, ζ b is the impeller internal loss coefficient, ζ1 is the blade inlet coefficient, ν is the hub diameter ratio, η v is the volumetric efficiency, μ o is the air flow filling coefficient at the impeller inlet section, and k is the correction coefficient; The calculation formula for b1 in step a is as follows: b1 = D1 / 4 * (1 - ν * ν) * μ o / ζ1 / μ1; where μ1 is the air flow filling coefficient at the blade inlet; The calculation formula for Z in step a is as follows: Z = 2.1 * σ * (D2 + D1) / (D2 - D1); where σ is the cascade density, Z1 is the number of inlet blades, Z2 is the number of outlet blades, Z1 and Z2 are obtained by rounding the calculated Z, and Z1 = Z2; The calculation formula for b2 in step a is as follows: b2 = b1 * ω1 / ω2 * μ1 / μ2 * (π * D1 * SIN(β b1 / 180 * π) - δ * Z1) / (π * D2 * SIN(β b2 / 180 * π) - Z2 * δ); Among them, β b1 is the integer value of β b1' rounded down, and β b1' = TANH(β b1' / π * 180); TAN(β b1' / π*180) = C 1r’ / U1; C 1r’ = Q / 3600 / η v / (D1 * π * b1 * μ1); U1 = D1 / 2 * (n * π / 30); Among them, μ2 is the fullness coefficient of the airflow at the blade outlet, δ is the blade thickness, β b1 is the blade inlet angle (degree), β b1' is the front blade inlet angle (degree), C 1r’ is the radial velocity before the blade inlet, and U1 is the linear velocity at the impeller inlet; The preset ω1 / ω2 = 1.8 in step b, and the calculation formula for ω1 is as follows: ω1 = C 1r / SIN(β b1 / 180*π); where C 1r = C 1r’ / τ1; τ1 = 1 - δ / SIN(β b1 / 180 * π) / D1 / π * Z1; C 1r’ = Q / 3600 / η v / (D1 * π * b1 * μ1); Among them, C 1r’ is the radial velocity before the blade inlet, τ1 is the blockage coefficient of the blade inlet section, C 1r is the radial velocity at the blade inlet, and ω1 is the relative velocity at the blade inlet; The calculation formula for ω2 is as follows: ω2 = C 2r / SIN(β b2 / 180*π); Among them, C 2r = Q / 3600 / η v / π / D2 / b2 / τ2 / μ2; τ2 = 1 - δ / SIN(β b2 / 180 * π) / D2 / π * Z2; Among them, τ2 is the blockage coefficient of the blade outlet section, C 2r is the radial velocity at the blade outlet, and ω2 is the relative velocity at the blade outlet; The air volume check formula in step c is as follows: Q = η v *τ1*π*D1*b1*C 1r’ *3600; The air pressure check formula is as follows: P = η h *μ*ρ*π^2*n^2*(D2^2 - D1^2*b2 / b1*TAN(β b1 / 180*π) / TAN(β b2 / 18 0*π)) / 60^2； where μ = 1 / (1+(1.5 + 1.1*β b2 / 90) / 24 / (1-(D1 / D2) 2 )) Among them, η h is the flow efficiency, and μ is the slip coefficient.

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