Digital design method for high-load fan / compressor

Abstract

The invention discloses a digital design method for a high-load fan / compressor. The digital design method comprises the steps that working parameters of the fan / compressor are defined, the specific speed is calculated, and the hub ratio is determined. The hub diameter is calculated through the hub ratio and the outer diameter of the movable impeller, and the airflow axial speed is solved by combining the volume flow. And calculating the diameter, the circumferential speed and the airflow twisting speed of the middle blade height section of the movable impeller, and determining an airflow angle and a turning angle through the speed triangle. Selecting any blade height section, defining a blade height scale factor, calculating the diameter, the circumferential speed and the airflow twisting speed, determining the consistency, the pitch and the chord length of the blade, and finally obtaining the geometric angle of the blade. And repeatedly calculating different section parameters to complete the design of the movable impeller. And meanwhile, after a static impeller of the fan / air compressor is designed, the overall design of the fan / air compressor is completed. According to the method, digital and flow design specifications are formed, the design period of the fan / air compressor is greatly shortened, and the research and development cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of machinery, and particularly relates to a digital design method for high-load fans / compressors. Background Art

[0002] Fans / compressors are important components of the cooling system of air-cooled engines. The cold air generated by the fans / compressors accumulates in the air pressure chamber, and a certain air pressure chamber pressure is established. Different air volumes are distributed according to the channel resistances of various components such as the cylinder head, cylinder block, oil cooler, and intercooler to ensure that each component can be reliably cooled. The selection and design quality of the fans / compressors directly affect the quality of the cooling system of air-cooled diesel engines, and then affect the reliability and economy of air-cooled diesel engines. Under the condition that the power consumed by driving the fans / compressors is equal, the air supply pressure of the fans / compressors of air-cooled diesel engines is required to be higher than that of water-cooled diesel engines. To increase the pressure coefficient, most fans / compressors are selected to be provided with stationary blades to increase the pressure, which further increases the design complexity. In recent years, with the improvement of the performance of diesel engines, the requirements for the cooling system have also been increasing day by day. A rapid and accurate design method for high-load fans / compressors is particularly important.

[0003] For the design of high-load fans / compressors, most traditional design methods adopt empirical design, that is, by adjusting the geometric structure parameters of existing prototypes to create multiple design schemes, and then performing performance tests to screen the best scheme. However, given the numerous geometric structure parameters of fans / compressors and the complex influence on performance, it is very difficult to achieve the optimization of the design only by experience, and at the same time, it also leads to a long R & D cycle and high R & D costs. Summary of the Invention

[0004] The purpose of the present invention is to provide a digital design method for high-load fans / compressors aiming at the technical defects existing in the prior art. By analyzing the working conditions, performance targets, and structural requirements of the fans / compressors, under given conditions such as flow rate and pressure, the best matching of the diameter, hub ratio, and working speed of the fans / compressors is determined, and then the blade profiles of the moving and stationary impellers are determined to realize the design of the fans / compressors of air-cooled engines.

[0005] To achieve the above purpose, the present invention provides a digital design method for high-load fans / compressors, including:

[0006] Specify the volume flow rate Q, rated speed n, total pressure P of the fan / compressor 0 , the design efficiency η of the fan / compressor, and the density ρ of the working medium; according to the volume flow rate Q, rated speed n, and total pressure P 0 , calculate the specific speed n s ;

[0007] According to the specific speed n s, determine the hub ratio ν, and the selection range of the hub ratio ν is:

[0008]

[0009] Wherein, the fan / compressor includes a rotating impeller and a stationary impeller, and the rotating impeller and the stationary impeller have the same hub diameter D h and outer diameter D t ;

[0010] According to the hub ratio ν and the outer diameter D of the rotating impeller t , calculate the hub diameter D h ;

[0011] According to the outer diameter D of the rotating impeller t , hub diameter D h and volume flow rate Q, calculate the axial air velocity c z ;

[0012] According to the outer diameter D of the rotating impeller t and hub diameter D h , calculate the diameter D of the middle blade height section of the rotating impeller midspan ;

[0013] According to the diameter D of the middle blade height section of the rotating impeller midspan calculate the circumferential velocity u of the middle blade height section of the rotating impeller midspan ;

[0014] According to the design efficiency η, total pressure P 0 of the fan / compressor, density ρ of the working medium, circumferential velocity u of the middle blade height section of the rotating impeller midspan , calculate the air flow twist velocity Δc of the middle blade height section of the rotating impeller u,midspan ;

[0015] Calculate the inlet relative air flow angle β 1,midspan , outlet relative air flow angle β 2,midspan and air flow turning angle Δβ midspan of the middle blade height section of the rotating impeller according to the velocity triangle;

[0016] Select any blade height section of the rotating impeller for design, define the blade height ratio factor as ξ, calculate the diameter D of any blade height section, and the circumferential velocity u of any blade height section of the rotating impeller;

[0017] According to the design efficiency η, total pressure P 0 of the fan / compressor, density ρ of the working medium, circumferential velocity u of any blade height section of the rotating impeller, calculate the air flow twist velocity Δc u of any blade height section of the rotating impeller;

[0018] Calculate the inlet relative air flow angle β of any blade height section of the rotating impeller according to the velocity triangle1 and the relative flow angle β at the outlet 2 as well as the flow turning angle Δβ;

[0019] Calculate the rated turning angle Δβ of any blade height section of the impeller * and the rated relative flow angle at the outlet

[0020] Based on the rated turning angle Δβ of any blade height section of the impeller * and the rated relative flow angle at the outlet select the blade pitch τ of any blade height section using the cascade rated characteristic curve;

[0021] Select the number of impeller blades z according to the hub ratio ν;

[0022] Calculate the pitch t of any blade height section according to the diameter D and the number of blades z of any blade height section of the impeller;

[0023] Calculate the chord length b of any blade height section of the impeller according to the blade pitch τ and the pitch t of any blade height section;

[0024] Select the rated incidence angle i of any blade height section of the impeller * , and based on the rated incidence angle i * , the chord length b, the rated turning angle Δβ * , the relative flow angle β at the outlet 2 , and the pitch t, calculate the blade profile turning angle θ and the rated outlet flow lag angle δ of any blade height section of the impeller * ;

[0025] According to the relative flow angle β at the inlet of any blade height section of the impeller 1 , the relative flow angle β at the outlet 2 , the rated incidence angle i * , and the rated outlet flow lag angle δ * , calculate the inlet blade geometric angle β 1A and the outlet blade geometric angle β 2A of any blade height section;

[0026] Select different blade height sections of the impeller and repeat the calculation to obtain the relevant parameters of all blade height sections of the impeller, completing the design of the impeller; at the same time, after designing the stator of the fan / compressor, complete the overall design of the fan / compressor.

[0027] Preferably, the formula expression of the specific speed n s is:

[0028]

[0029] Preferably, the hub diameter D hThe formula expression is:

[0030] D h = ν × D t

[0031] The axial velocity c of the air flow z The formula expression is:

[0032]

[0033] The diameter D of the middle blade height section of the impeller midspan The formula expression is:

[0034] D midspan =(D h + D t ) / 2

[0035] The circumferential velocity u of the middle blade height section of the impeller midspan The formula expression is:

[0036]

[0037] Preferably, the air flow twist velocity Δc of the middle blade height section of the impeller u,midspan The formula expression is:

[0038]

[0039] Calculate the inlet relative air flow angle β 1,midspan 、the outlet relative air flow angle β 2,midspan and the air flow turning angle Δβ midspan of the middle blade height section of the impeller according to the velocity triangle. The formula expressions include:

[0040]

[0041] Δβ midspan = β 2,midspan - β 1,midspan

[0042] Select any blade height section of the impeller for design. Define the blade height ratio factor as ξ. The formula expressions for calculating the diameter D of any blade height section and the circumferential velocity u of any blade height section of the impeller include:

[0043] D = D h +(D t - D h )ξ

[0044]

[0045] Preferably, the air flow twist velocity Δc of any blade height section of the impeller uThe formula expression is:

[0046]

[0047] According to the velocity triangle, the formula expressions for calculating the inlet relative air flow angle β 1 and the outlet relative air flow angle β 2 as well as the air flow turning angle Δβ of any blade height section of the impeller include:

[0048]

[0049] Δβ = β 2 - β 1

[0050] Calculate the rated turning angle Δβ of any blade height section of the impeller * and the rated outlet relative air flow angle The formula expressions include:

[0051] Δβ * = 0.8Δβ midspan

[0052]

[0053] Preferably, according to the rated turning angle Δβ of any blade height section of the impeller * and the rated outlet relative air flow angle The formula expression for selecting the blade pitch τ of any blade height section by using the rated characteristic curve of the cascade is:

[0054]

[0055] Where

[0056]

[0057] Preferably, according to the size of the hub ratio ν, the formula expression for selecting the number of impeller blades z is:

[0058]

[0059] According to the diameter D and the number of blades z of any blade height section of the impeller, the formula expression for calculating the pitch t of any blade height section is:

[0060]

[0061] According to the blade pitch τ and the pitch t of any blade height section of the impeller, the formula expression for calculating the chord length b of any blade height section of the impeller is:

[0062] b = τ × t.

[0063] Preferably, calculate the blade profile turning angle θ and the rated outlet air flow lag angle δ of any blade height section of the impeller * The formula expressions include:

[0064]

[0065] where j = 0.3663 - 0.002β 2 ;

[0066] Calculate the inlet blade geometric angle β 1A and the outlet blade geometric angle β 2A of any blade height section. The formula expressions include:

[0067] β 1A = β 1 + i *

[0068] β 2A = β 2 + δ * .

[0069] Preferably, the stationary impeller of the fan / compressor is selected as a front stationary impeller.

[0070] Preferably, the process of designing the stationary impeller of the fan / compressor includes:

[0071] Given that the inlet air flow angle α 0 = 90° of any blade height section of the stationary impeller, calculate the tangential velocity c 0 at the outlet of any blade height section of the front stationary impeller according to the diameter D, total pressure P 1u of any blade height section and the density ρ of the working medium;

[0072] The formula expression is:

[0073]

[0074] where n 1 ranges from -0.5 to -0.6, and the angular velocity When selecting the middle blade height section of the stationary impeller where D = D midspan , c 1u = c 1u,midspan ;

[0075] Calculate the outlet air flow angle α 1 at any blade height section of the stationary impeller; the formula expression is:

[0076]

[0077] When selecting the middle blade height section of the stationary impeller,

[0078] Replace the inlet relative airflow angle β 1,midspan and the outlet relative airflow angle β 2,midspan of the variable moving impeller at the middle blade height section with the inlet airflow angle α 0,midspan = 90° and the outlet airflow angle α 1,midspan , and calculate the airflow turning angle Δα midspan at the middle blade height section of the front stator impeller:

[0079] Δα midspan = α 1,midspan - 90°

[0080] Replace the variable airflow turning angle Δβ midspan at the middle blade height of the variable moving impeller, the rated turning angle Δβ * at any blade height section, the rated outlet relative airflow angle the outlet relative airflow angle β 2 , the inlet relative airflow angle β 1 , the inlet blade geometric angle β 1A , and the outlet blade geometric angle β 2A with the relevant variables of the stator impeller: the airflow turning angle Δα midspan at the middle blade height of the front stator impeller, the rated turning angle Δα * at any blade height section, the rated outlet relative airflow angle the outlet relative airflow angle α 1 , the inlet airflow angle α 0 , the inlet blade geometric angle β 1A , and the outlet blade geometric angle β 2A to obtain the calculation formula applicable to the design of the stator impeller;

[0081] Select different blade heights of the front stator impeller, and calculate the relevant parameters of all blade height sections of the front stator impeller according to the replaced variables and the calculation formula applicable to the design of the stator impeller to complete the design of the front stator impeller of the fan / compressor.

[0082] Compared with the prior art, the present invention has the following advantages and technical effects:

[0083] The digital design method of the high-load fan / compressor of the present invention uses theoretical formulas for calculation, avoiding a large number of trial-and-error attempts required in the traditional design method based on experience, and can ensure that the designed fan / compressor is an optimal solution in principle.

[0084] The digital design method of the high-load fan / compressor of the present invention forms a digital and process-based design specification, greatly shortening the design cycle of the fan / compressor and reducing the R & D cost. Description of the Drawings

[0085] The accompanying drawings, which form a part of this application, are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0086] Figure 1 It is a schematic flow chart of the method according to the embodiment of the present invention. Detailed implementation manners

[0087] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will refer to the accompanying drawings and combine with the embodiments to detail this application.

[0088] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0089] As Figure 1 shown, a high-load fan / compressor digital design method is provided in this embodiment, including the following steps:

[0090] (1) Given the volume flow rate Q, rated speed n, total pressure P of the fan / compressor 0 , the fan / compressor design efficiency η, and the working medium density ρ; according to the volume flow rate Q, rated speed n, and total pressure P 0 , calculate the specific speed n s , and the calculation formula is:

[0091]

[0092] (2) The fan / compressor includes a rotating impeller and a stationary impeller, and the rotating impeller and the stationary impeller have the same hub diameter D h and outer diameter D t . According to the specific speed n s , select a suitable hub ratio ν, and the selection range is:

[0093]

[0094] (3) Given the outer diameter D of the rotating impeller t , according to the hub ratio ν and the outer diameter D of the rotating impeller t , calculate the hub diameter D h , and the calculation formula is:

[0095] D h = ν × D t (3)

[0096] (4) According to the outer diameter D of the rotating impeller t , the hub diameter Dh and the volumetric flow rate Q, calculate the axial velocity c of the air flow z , and the calculation formula is:

[0097]

[0098] (5) According to the outer diameter D of the impeller t , the hub diameter D h , calculate the diameter D of the middle blade height section of the impeller midspan , and the calculation formula is:

[0099] D midspan =(D h +D t ) / 2(5)

[0100] Calculate the circumferential velocity u of the middle blade height section of the impeller midspan , and the calculation formula is:

[0101]

[0102] (6) According to the design efficiency η of the fan / compressor, the total pressure P 0 , the density ρ of the working medium, and the circumferential velocity u of the middle blade height section of the impeller midspan , calculate the airflow twist velocity Δc of the middle blade height section of the impeller u,midspan , and the calculation formula is:

[0103]

[0104] (7) Calculate the inlet relative airflow angle β 1,midspan of the middle blade height section of the impeller, the outlet relative airflow angle β 2,midspan and the airflow turning angle Δβ midspan according to the velocity triangle:

[0105]

[0106] Δβ midspan =β 2,midspan -β 1,midspan (10)

[0107] (8) Select any blade height section of the impeller for design. If its blade height ratio factor is ξ, then the calculation formula for the diameter D of any blade height section is:

[0108] D = D h +(D t -D h )ξ(11)

[0109] Calculate the circumferential velocity u of any blade height section of the impeller, and the calculation formula is:

[0110]

[0111] (9) Calculate the airflow twist velocity Δc at any blade height section of the impeller according to the fan / compressor design efficiency η, total pressure P 0 , working medium density ρ, and circumferential velocity u of any blade height section of the impeller. The calculation formula is: u

[0112]

[0113] (10) Calculate the inlet relative airflow angle β 1 and outlet relative airflow angle β 2 of any blade height section of the impeller, as well as the airflow turning angle Δβ:

[0114]

[0115] Δβ = β 2 - β 1 (16)

[0116] (11) Calculate the rated turning angle Δβ * and rated outlet relative airflow angle of any blade height section of the impeller. The calculation formula is:

[0117] Δβ * = 0.8Δβ midspan (17)

[0118]

[0119] (12) Select the blade pitch τ of any blade height section using the rated characteristic curve of the cascade according to the rated turning angle Δβ * and rated outlet relative airflow angle of any blade height section of the impeller. The formula is as follows:

[0120]

[0121] Where

[0122]

[0123] (13) Select the number of impeller blades z according to the hub ratio ν. The calculation formula is:

[0124]

[0125] (14) Calculate the pitch t of any blade height section according to the diameter D and number of blades z of any blade height section of the impeller. The calculation formula is:

[0126] ​

[0127] (15) Calculate the chord length b of the blade at any height section of the impeller according to the blade pitch τ and the pitch t at the same height section of the impeller. The calculation formula is:

[0128] b = τ × t (22)

[0129] (16) Select the rated incidence angle i at any height section of the impeller * , generally within -5 to 5°. According to the rated incidence angle i * , the chord length b of the blade, the rated turning angle Δβ * , the relative outlet flow angle β of the outlet 2 , and the pitch t, calculate the blade turning angle θ and the rated outlet flow lag angle δ at any height section of the impeller * . The calculation formula is:

[0130]

[0131] where j = 0.3663 - 0.002β 2

[0132] (17) According to the relative inlet flow angle β 1 and the relative outlet flow angle β 2 at any height section of the impeller, the rated incidence angle i * , and the rated outlet flow lag angle δ * , calculate the inlet blade geometric angle β 1A and the outlet blade geometric angle β 2A at any height section. The calculation formula is:

[0133] β 1A = β 1 + i * (25)

[0134] β 2A = β 2 + δ * (26)

[0135] (18) Select different height sections of the impeller and repeat steps (8) to (17) to calculate the relevant parameters of all height sections of the impeller, thus completing the design of the impeller.

[0136] (19) Design the stator of the fan / compressor. To increase the load of the fan / compressor, a pre-stator is selected. The specific design steps are as follows:

[0137] Ⅰ) Given that the inlet flow angle α 0 = 90° at any height section of the pre-stator. According to the diameter D, the total pressure P 0 at any height section, and the density ρ of the working medium, calculate the tangential velocity c at the outlet of any height section of the pre-stator1u , the calculation formula is:

[0138]

[0139] where n 1 generally takes values from -0.5 to -0.6, and the angular velocity When the middle blade height section D = D of the stationary impeller is selected midspan , c 1u = c 1u,midspan ;

[0140] II) Calculate the outlet airflow angle α of any blade height section of the front stationary impeller 1 , the calculation formula is:

[0141]

[0142] When the middle blade height section of the stationary impeller is selected,

[0143] III) Replace the variables in step (7): the relative airflow angle β at the inlet of the middle blade height section of the rotating impeller 1,midspan , the relative airflow angle β at the outlet 2,midspan with the inlet airflow angle α of the middle blade height section of the front stationary impeller 0,midspan = 90°, the outlet airflow angle α 1,midspan , and according to formula (10), the airflow turning angle Δα of the middle blade height section of the front stationary impeller can be obtained midspan :

[0144] Δα midspan = α 1,midspan - 90° (29)

[0145] IV) Replace the variables in steps (11) to (17): the airflow turning angle Δβ of the middle blade height section of the rotating impeller midspan , the rated turning angle Δβ of any blade height section * , the rated outlet relative airflow angle the outlet relative airflow angle β 2 , the inlet relative airflow angle β 1 , the inlet blade geometric angle β 1A , the outlet blade geometric angle β 2A , with the relevant variables of the front stationary impeller: the airflow turning angle Δα of the middle blade height section of the front stationary impeller midspan , the rated turning angle Δα of any blade height section * , the rated outlet relative airflow angle the outlet relative airflow angle α 1 , the inlet airflow angle α 0 , the inlet blade geometric angle β 1A , the outlet blade geometric angle β 2A, the formula applicable to the design of the front stationary impeller can be obtained. Select different blade heights of the front stationary impeller, and repeat steps (11) to (17) with the replaced variables to calculate the relevant parameters of all blade height sections of the front stationary impeller, thus completing the design of the front stationary impeller of the fan / compressor.

[0146] The following takes the design of the fan / compressor of a certain air-cooled diesel engine as an example for illustration:

[0147] (1) Given the volume flow rate Q = 3.876 m 3 / s, the rated speed n = 6045 r / min, the total pressure P 0 = 5400 Pa, the design efficiency η = 0.8 of the fan / compressor, and the density ρ = 1.29 kg / m 3 of the working medium. Calculate the specific speed n s = 27.93 according to Equation (1);

[0148] (2) Given the specific speed n s , select the hub ratio ν = 0.554 according to Equation (2);

[0149] (3) Given the outer diameter D t = 388 mm of the impeller, calculate the hub diameter D h = 215 mm according to Equation (3);

[0150] (4) Calculate the axial velocity c z = 56.8 m / s of the air flow according to Equation (4);

[0151] (5) Calculate the diameter D midspan = 0.3137 m of the middle blade height section of the impeller according to Equation (5), and calculate the circumferential velocity u midspan = 99.29 m / s according to Equation (6);

[0152] (6) Calculate the air flow twist velocity Δc u,midspan = 57.29 m / s of the middle blade height section of the impeller according to Equation (7);

[0153] (7) Calculate the relative air flow angles β 1,midspan = 30.70°, β 2,midspan = 56.12° at the inlet and outlet of the middle blade height section of the impeller and the air flow turning angle Δβ midspan = 26° according to Equations (8), (9), and (10);

[0154] (8) Select the blade root and blade tip sections for design, and the blade height ratio factors are ξ h = 0, ξ t = 1; calculate the diameters D h , D t respectively according to Equation (11); calculate the circumferential velocity uh = 72.71 m / s, u t = 131.19 m / s;

[0155] (9) Calculate the air flow twist velocity Δc at each section of the impeller according to Equation (13) u,h = 48.38 m / s, Δc u,t = 37.35 m / s;

[0156] (10) Calculate the inlet and outlet relative air flow angles β at each section of the impeller according to Equation (14), Equation (15), and Equation (16) 1,h = 37.99°, β 2,h = 46.81°, β 1,t = 23.41°, β 2,t = 37.8°, and the air flow turning angle Δβ h = 10°, Δβ t = 14°;

[0157] (11) Calculate the rated turning angle Δβ of the impeller according to Equation (17) and Equation (18) * = 20.8, the rated outlet relative air flow angle at each section

[0158] (12) Determine the blade pitch τ at each section of the impeller according to Equation (19) h = 0.67, τ midspan = 1.07, τ t = 1.47;

[0159] (13) Select the number of impeller blades z = 11 according to Equation (20);

[0160] (14) Calculate the grid pitch t according to Equation (21) h = 61.96 mm, t midspan = 86.385 mm, t t = 110.81 mm;

[0161] (15) Calculate the blade chord length b of the impeller according to Equation (22) h = 90.80 mm, b midspan = 82.285 mm, b t = 90.80 mm;

[0162] (16) Select the rated incidence angle Calculate the rated outlet air flow lag angle according to Equation (23) and Equation (24)

[0163] (17) Calculate the blade geometric angles β at the inlet and outlet of each section according to Equation (25) and Equation (26) 1A , β 2A, The summary of the calculated results of the impeller parameters is shown in Table 1:

[0164] Table 1

[0165]

[0166]

[0167] (18) Design the stationary impeller of the fan / compressor:

[0168] Ⅰ) Select the fan / compressor configuration with a stationary impeller in front of the impeller. Calculate the tangential velocity c at the outlet of each blade height section of the stationary impeller in front according to Equation (27) 1u,h =-50.51 m / s, c 1u,midspan =-51.71 m / s, c 1u,t =-52.89 m / s;

[0169] Ⅱ) Calculate the outlet airflow angle α of the stationary impeller in front according to Equation (28) 1,h =143.75°, α 1,midspan =138.46°, α 1,t =132.96°;

[0170] Ⅲ) Calculate the airflow turning angle Δα at the middle blade height section of the stationary impeller in front according to Equation (29) midspan =48°;

[0171] Ⅳ) Replace the variables in steps (11) - (17): the airflow turning angle Δβ at the middle blade height of the impeller, the rated turning angle Δβ at any blade height section, the rated outlet relative airflow angle midspan , the outlet relative airflow angle β * , the inlet relative airflow angle β , the outlet relative airflow angle β 2 , the inlet relative airflow angle β 1 , the inlet blade geometric angle β 1A , the outlet blade geometric angle β 2A , with the relevant variables of the stationary impeller in front: the airflow turning angle Δα at the middle blade height of the stationary impeller in front midspan , the rated turning angle Δα at any blade height section, the rated outlet relative airflow angle * , the outlet relative airflow angle α , the inlet airflow angle α 1 , the inlet blade geometric angle β 0 , the outlet blade geometric angle β 1A , the outlet blade geometric angle β 2A , then the formula applicable to the design of the stationary impeller in front can be obtained. Select different blade heights of the stationary impeller in front and repeat steps (11) - (17) with the replaced variables to calculate the relevant parameters of all blade height sections of the stationary impeller in front, and complete the design of the stationary impeller of the fan / compressor. The summary of the calculated results of the parameters of the stationary impeller in front is shown in Table 2:

[0172] Table 2

[0173]

[0174] The high-load fan / compressor digital design method disclosed in this embodiment improves the design efficiency of the fan / compressor of the air-cooled machine on the premise of ensuring the high load and high total pressure of the fan / compressor of the air-cooled machine. By analyzing the working conditions, performance targets, and structural requirements of the fan / compressor, the optimal matching of the fan / compressor diameter, hub ratio, and operating speed is determined under given conditions such as flow rate and pressure, and then the blade profiles of the moving and stationary impellers are determined, realizing the digital design of the fan / compressor of the air-cooled machine. Applying this method to the digital design of the fan / compressor of the air-cooled machine can ensure that the designed fan / compressor is an optimal solution, significantly reduce the design time, and lower the R & D cost.

[0175] The above is only the preferred specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high-load fan / compressor digital design method, characterized in that: include: Given the volume flow Q, rated speed n, total pressure P0, fan / compressor design efficiency η, and working medium density ρ of the fan / compressor; According to the volume flow Q, rated speed n, and total pressure P0, calculate the specific speed n s ; According to the specific speed n s , determine the hub ratio ν, the selection range of the hub ratio ν is: The fan / compressor includes a moving impeller and a stationary impeller, and the moving impeller and the stationary impeller have the same hub diameter D h and outer diameter D t ; According to the hub ratio ν and the impeller outer diameter D t , calculate the hub diameter D h ; According to the outer diameter D of the impeller t , hub diameter D h and volume flow rate Q, calculate the axial velocity c of the air flow z ; According to the outer diameter D of the impeller t and hub diameter D h , calculate the diameter D of the middle blade height section of the impeller midspan ; According to the impeller intermediate blade height cross-sectional diameter D midspan Calculate the circumferential velocity u of the middle blade height section of the impeller midspan ; According to the design efficiency η of the fan / compressor, the total pressure P0, the working medium density ρ, the circumferential speed u of the intermediate blade height section of the impeller midspan , calculate the airflow twisting speed Δc of the middle blade height section of the impeller u,midspan ; Calculate the relative airflow angle β at the inlet of the impeller's intermediate blade height section based on the velocity triangle 1,midspan , outlet relative airflow angle β 2,midspan and the airflow turning angle Δβ midspan ; Select an arbitrary blade height section of the impeller for design, define the blade height proportional factor as ξ, calculate the diameter D of the arbitrary blade height section, and the circumferential speed u of the arbitrary blade height section of the impeller; According to the fan / compressor design efficiency η, total pressure P0, working medium density ρ, and impeller arbitrary blade high section circumferential speed u, calculate the impeller arbitrary blade high section airflow twist speed Δc u ; According to the velocity triangle, the inlet relative airflow angle β1, outlet relative airflow angle β2 and airflow turning angle Δβ of any blade height section of the impeller are calculated; Calculate the rated turning angle Δβ of the impeller at any blade height * , Rated outlet relative airflow angle According to the rated turning angle Δβ of the impeller at any blade height section * , Rated outlet relative airflow angle The blade density τ of any blade height section is selected using the blade cascade rated characteristic curve; According to the hub ratio ν, select the number of impeller blades z; According to the impeller's arbitrary blade height section diameter D and the number of blades z, calculate the arbitrary blade height section pitch t; According to the blade density τ and the pitch t of the impeller blade with arbitrary blade height, the chord length b of the impeller blade with arbitrary blade height is calculated; Select the rated angle of attack i of the impeller at any blade height section * , according to the rated angle of attack i * , blade chord length b, rated turning angle Δβ * , outlet relative airflow angle β2, grid pitch t, ​​calculate the impeller arbitrary blade high section blade turning angle θ, rated outlet airflow backward angle δ * ; According to the relative airflow angle β1 of the inlet of the impeller at any blade height section, the relative airflow angle β2 of the outlet, and the rated angle of attack i * 、Rated outlet airflow backward angle δ * , calculate the geometric angle β of the inlet blade of any blade height section 1A , outlet blade geometric angle β 2A ; Select different blade height sections of the moving impeller, repeatedly calculate the relevant parameters of all blade height sections of the moving impeller, and complete the design of the moving impeller; at the same time, after designing the static impeller of the fan / compressor, complete the overall design of the fan / compressor.

2. The method according to claim 1, characterized in that The specific speed n s The formula expression is:

3. The method according to claim 1, characterized in that The hub diameter D h The formula expression is: D h =ν×D t The air flow axial velocity c z The formula expression is: The impeller intermediate blade high section diameter D midspan The formula expression is: D midspan =(D h +D t ) / 2 The circumferential speed u of the middle blade high section of the impeller midspan The formula expression is:

4. The method according to claim 1, characterized in that: The high cross-sectional airflow twist speed Δc of the intermediate blade of the impeller u,midspan The formula expression is: Calculate the relative airflow angle β at the inlet of the impeller's intermediate blade height section based on the velocity triangle 1,midspan , outlet relative airflow angle β 2,midspan and the airflow turning angle Δβ midspan The formula expressions include: Db midspan =b 2,midspan -b 1,midspan Select an arbitrary blade height section of the impeller for design, define the blade height proportional factor as ξ, calculate the diameter D of the arbitrary blade height section, and the formula expression of the circumferential speed u of the arbitrary blade height section of the impeller includes: D=D h +(D t -D h )ξ 5. The method according to claim 1, characterized in that The airflow twisting speed Δc of the impeller at any blade height cross section u The formula expression is: The formulas for calculating the inlet relative airflow angle β1, outlet relative airflow angle β2 and airflow turning angle Δβ of any blade height section of the impeller according to the velocity triangle include: Δβ=β2-β1 Calculate the rated turning angle Δβ of the impeller at any blade height * , Rated outlet relative airflow angle The formula expressions include: Db * =0.8Δβ midspan 6. The method according to claim 1, characterized in that According to the rated turning angle Δβ of the impeller at any blade height section * , Rated outlet relative airflow angle The formula for selecting the blade density τ of any blade height section using the blade cascade rated characteristic curve is: in 7. The method according to claim 1, characterized in that According to the hub ratio ν, the formula for selecting the number of impeller blades z is: According to the impeller's arbitrary blade height section diameter D and the number of blades z, the formula for calculating the arbitrary blade height section pitch t is: According to the blade density τ and pitch t of the impeller blade with arbitrary blade height section, the formula for calculating the chord length b of the impeller blade with arbitrary blade height section is: b = τ × t.

8. The method according to claim 1, characterized in that Calculate the impeller blade profile turning angle θ and rated outlet airflow backward angle δ of any blade height section * The formula expressions include: Where, j = 0.3663-0.002β2; Calculate the geometric angle β of the inlet blade of any blade height section 1A , outlet blade geometric angle β 2A The formula expressions include: β 1A ＝β1+i * b 2A =β2+δ * 。 9. The method according to claim 1, characterized in that: The stator impeller of the fan / compressor is a front-mounted stator impeller.

10. The method according to claim 1, characterized in that The process of designing the stator wheel of the fan / compressor includes: Given that the inlet airflow angle of the arbitrary blade height section of the static impeller is α0 = 90°, the tangential velocity c at the outlet of the arbitrary blade height section of the front static impeller is calculated based on the diameter D of the arbitrary blade height section, the total pressure P0, and the density ρ of the working medium. 1u ; The formula expression is: Among them, n1 ranges from -0.5 to -0.6, and the angular velocity When the static impeller intermediate blade height section D is selected midspan When c 1u =c 1u,midspan ; Calculate the outlet airflow angle α1 of the stator impeller at any blade height section; the formula is: When selecting the middle blade height section of the stationary impeller, The relative airflow angle β of the inlet of the intermediate blade height section of the variable impeller 1,midspan , outlet relative airflow angle β 2,midspan Replaced by the inlet airflow angle α of the intermediate blade height section of the stationary impeller 0,midspan =90°, outlet airflow angle α 1,midspan , calculate the airflow turning angle Δα of the intermediate blade height section of the front static impeller midspan : Da midspan =a 1,midspan -90° The airflow turning angle Δβ of the intermediate blade height of the variable impeller midspan , Rated turning angle Δβ of any blade height section * , Rated outlet relative airflow angle Outlet relative airflow angle β2, inlet relative airflow angle β1, inlet blade geometric angle β 1A , outlet blade geometric angle β 2A , replaced by the static impeller related variables: the front static impeller intermediate blade height airflow turning angle Δα midspan 、Rated turning angle Δα of any blade height section * , Rated outlet relative airflow angle Outlet relative airflow angle α1, inlet airflow angle α0, inlet blade geometric angle β 1A , outlet blade geometric angle β 2A , obtain the calculation formula suitable for the design of the stationary impeller; Select different blade heights of the front static impeller, calculate the relevant parameters of all blade height sections of the front static impeller according to the replaced variables and the calculation formula applicable to the static impeller design, and complete the design of the fan / compressor front static impeller.

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