Design method of twisted blade, twisted blade and application of twisted blade

Abstract

The invention relates to the field of centrifugal pump design, in particular to a twisted blade design method, a twisted blade and application of the twisted blade. Dimension parameters, twisted blade parameters and centrifugal pump parameters are obtained; a three-dimensional model is established according to the size parameters, the twisted blade parameters and the centrifugal pump parameters, and twisted blade bone lines are obtained based on the three-dimensional model; fitting the twisted blade bone line to obtain a fitted twisted blade bone line; and determining the twisted blade based on the fitted twisted blade bone line. The twisted design of the blades is achieved by increasing the wrap angles of the blades, the blades are wound around the hub, the circulation area is effectively increased, the flow guiding effect can be achieved, the working efficiency of the pump is improved, the inlet section is arranged, installation of inlet guide blades is omitted, the axial size of the pump is effectively reduced, the centrifugal pump structure is more compact, and the service life of the pump is prolonged. And the maintenance cost of the centrifugal pump is reduced.

Description

Technical Field

[0001] The invention relates to the field of centrifugal pump design, and in particular to a twisted blade design method, a twisted blade and applications thereof. Background Art

[0002] Centrifugal pumps are widely used in the fields of industry, agriculture, municipal water supply, etc. as fluid conveying equipment. Their performance directly affects the operating efficiency and stability of the system. However, centrifugal pumps are prone to cavitation when conveying liquids, especially when running at high speeds. Cavitation refers to the phenomenon that when the local pressure of the liquid is reduced to the saturated vapor pressure at that location, bubbles are generated in the liquid inside the pump and quickly collapse. Cavitation will not only reduce the efficiency of the pump, but also increase the vibration and noise of the pump, and in severe cases, even cause damage to the pump.

[0003] In order to improve the cavitation performance of centrifugal pumps, one of the commonly used methods is to improve the structural parameters of the pump inlet, which specifically includes the following measures: 1. By increasing the flow area at the pump inlet, the flow velocity of the liquid can be reduced and the risk of cavitation can be reduced; 2. Increasing the radius of curvature of the impeller cover inlet section can improve the flow state of the liquid, thereby reducing the possibility of cavitation; 3. Reducing the blade inlet thickness can reduce the flow resistance of the liquid at the blade inlet and reduce the occurrence of cavitation; 4. Using a front inducer, the front inducer can pre-pressurize the liquid before it enters the impeller, increase the pressure of the liquid and reduce the occurrence of cavitation.

[0004] However, although the above-mentioned improvement measures have improved the cavitation performance of the centrifugal pump to a certain extent, they have also brought some new problems. For example, improving the structural parameters of the pump inlet may lead to flow separation and the generation of vortices, thereby increasing hydraulic losses and noise, and affecting the operating stability of the pump; the use of a front inducer will increase the structural complexity of the pump and increase manufacturing costs, and may also make maintenance and repair more difficult. In addition, the matching problem between the inducer and the impeller can easily lead to unstable flow and inability to continuously increase pressure, which will lead to reduced efficiency of the centrifugal pump and poor cavitation performance. Summary of the invention

[0005] In response to the problems mentioned in the prior art, the present invention proposes a twisted blade design method, a twisted blade and an application thereof. The twisted design of the blade is achieved by increasing the blade wrap angle. The twisted blade is wrapped around the hub, which effectively increases the flow area and improves the working efficiency of the pump. The blade inlet section is arranged with equal pitch to increase the fluid pressure of the inlet section, reduce the cavitation margin, reduce the axial size of the pump, make the centrifugal pump structure more compact, and reduce the maintenance cost of the centrifugal pump. It is proposed to use the trigonometric polynomial fitting method according to the least squares principle to regress the blade skeleton line, and obtain the fitting function expression of the blade skeleton line, which is convenient for optimization and application in engineering practice.

[0006] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention proposes a method for designing a twisted blade, comprising the following steps: Obtain dimensional parameters, twisted blade parameters, and centrifugal pump parameters; Establish a three-dimensional model based on the dimensional parameters, twisted blade parameters, and centrifugal pump parameters, and obtain the twisted blade backbone curve from the three-dimensional model; Fit the twisted blade backbone curve to obtain the fitted twisted blade backbone curve; Determine the twisted blade based on the fitted twisted blade backbone curve.

[0007] As a further improvement of the present invention, the dimensional parameters include the equivalent diameter at the impeller inlet, the hub diameter, the inlet diameter of the twisted blade, the impeller outlet diameter, and the outlet width; The calculation formula for the equivalent diameter at the impeller inlet is as follows:

[0008] In the formula: represents the equivalent diameter at the impeller inlet, unit: mm; represents the correction coefficient, selected according to the actual project, unit: dimensionless; Q represents the flow rate, unit: m 3 / h; represents the rotational speed, unit: r / min; represents the volumetric efficiency, unit: dimensionless; The calculation formula for the hub diameter is as follows:

[0009] In the formula: represents the hub ratio, determined according to the cross-sectional shape, unit: dimensionless; represents the hub diameter, unit: mm; The calculation formula for the inlet diameter of the twisted blade is as follows:

[0010] In the formula: represents the inlet diameter of the twisted blade, unit: mm; The calculation formula for the impeller outlet diameter is as follows:

[0011]

[0012] In the formula: represents the impeller outlet diameter, unit: mm; represents the modification coefficient of the impeller outlet diameter, unit: dimensionless; represents the correction coefficient, determined according to the structure of the pump, unit: dimensionless; Denotes the specific speed, unit: dimensionless; The calculation formula for the outlet width is as follows:

[0013]

[0014] In the formula: Denotes the outlet width, unit: mm; Denotes the modification coefficient of the impeller outlet width, unit: dimensionless; Denotes the correction coefficient, unit: dimensionless.

[0015] As a further improvement of the present invention, the twisted blade parameters include the twisted blade tip wrap angle, the short blade tip wrap angle, the short blade hub wrap angle, the total number of blades, the lead of the twisted blade inlet section, the pitch of the twisted blade inlet section, the axial distance on the rim side, and the axial distance on the hub side; The calculation formula for the twisted blade tip wrap angle is as follows:

[0016] In the formula: Denotes the twisted blade tip wrap angle, unit: °; Denotes the inlet sweep angle, taking 60° - 130°; Denotes the setting angle of the tip airfoil, unit: °; Denotes the airfoil cascade density, unit: dimensionless; Denotes the number of twisted blades, unit: piece; Denotes the cosine function; The calculation formula for the short blade tip wrap angle is as follows:

[0017] In the formula: Denotes the short blade tip wrap angle, unit: °; The calculation formula for the short blade hub wrap angle is as follows:

[0018] In the formula: Denotes the short blade hub wrap angle, unit: °.

[0019] As a further improvement of the present invention, the lead of the twisted blade inlet section is calculated as follows:

[0020] In the formula: Denotes the lead of the twisted blade inlet section, unit: mm; Denotes the average tip diameter, unit: mm; Denotes the setting angle of the tip airfoil, unit: °; represents the tangent function; The pitch calculation formula for the inlet section of the twisted blade is as follows:

[0021] In the formula: represents the pitch of the inlet section of the twisted blade, unit: mm; The calculation formula for the axial distance on the hub side is as follows:

[0022] In the formula: represents the axial distance on the hub side, unit: mm; The calculation formula for the axial distance on the rim side is as follows:

[0023] In the formula: represents the axial distance on the rim side, unit: mm.

[0024] As a further improvement of the present invention, the total number of blades is determined according to the setting angle of the rim airfoil; the total number of blades includes the number of twisted blades and the number of main impeller blades, wherein the number of twisted blades and the number of main impeller blades are set as multiples of each other, and the number of twisted blades is odd.

[0025] As a further improvement of the present invention, the calculation formula for the total number of blades is as follows:

[0026] In the formula: represents the total number of blades, unit: piece; represents the inlet diameter of the twisted blade, unit: mm; represents the outlet diameter of the impeller, unit: mm; represents the setting angle of the rim airfoil, unit: °; represents the setting angle of the hub airfoil, unit: °; sin represents the sine function.

[0027] As a further improvement of the present invention, a three-dimensional model diagram is constructed by CFturbo software, and the spatial blade profile diagram of the twisted blade is drawn according to the three-dimensional model diagram, and the blade skeleton line in the spatial blade profile diagram is extracted.

[0028] As a further improvement of the present invention, the second-order trigonometric polynomial is used to fit the twisted blade skeleton line, and the second-order trigonometric polynomial model is as follows:

[0029]

[0030]

[0031] In the formula: represents a constant; represents the coefficient of the th-order cosine term; represents the coefficient of the th-order sine term; represents the polynomial degree; and represent the order; represents the sine function.

[0032] In a second aspect, the present invention provides a twisted blade, which is designed by the above method.

[0033] In a third aspect, the present invention provides a centrifugal pump applying the above twisted blade.

[0034] Compared with the prior art, the present invention has achieved the following technical effects: The blade design method provided by the present invention aims to improve the cavitation performance of the pump. By combining multiple parameters to calculate the shroud angle of the blade, the blade is a twisted structure and wound around the hub, which can effectively increase the flow area and improve the working efficiency of the pump; by arranging an equal pitch at the inlet section of the blade, the fluid pressure at the inlet section can be increased, the cavitation margin can be reduced, the axial dimension of the pump can be reduced, the structure of the centrifugal pump can be made more compact, and the maintenance cost of the centrifugal pump can be reduced; according to the least square method principle, the blade camber line is regressed and analyzed by using the trigonometric polynomial fitting method, realizing the accurate description of the blade geometry. The method of the present invention can provide a theoretical basis for the retrofit and optimization design of the blade, and can quickly and accurately adjust the blade parameters to further improve the performance of the pump.

[0035] The twisted blade designed by the present invention has the characteristics of a large shroud angle and a small incidence angle, which can effectively reduce the pressure drop when the liquid working medium flows around the blade profile, reduce the flow loss, and thus improve the fluid efficiency and energy conversion efficiency of the centrifugal pump; The twisted blade is wound around the hub, significantly increasing the flow area, realizing a good guiding effect, improving the hydrodynamic performance of the pump. At the same time, the centrifugal force is small, and the liquid working medium is not easy to generate gas-liquid separation during the flow process, effectively improving the cavitation performance of the centrifugal pump and extending the service life of the pump.

[0036] To ensure a uniform distribution of the axial velocity in the radial direction of the inlet flow field, the inlet section of the twisted blade is designed with an equal pitch arrangement, effectively avoiding the flow loss caused by uneven flow velocity distribution and further optimizing the inlet flow conditions of the pump. At the same time, a relatively high cascade density is set at the inlet section of the blade, so that the maximum pressure drop point is located in the outer edge area of the blade, which is far from the blade inlet and has a relatively high fluid pressure, reducing the critical effective cavitation margin. The installed inlet section eliminates the installation of the inlet guide vane in the traditional centrifugal pump, not only effectively reducing the axial distance, but also making the overall structure of the centrifugal pump more compact, reducing the manufacturing cost and installation difficulty. Brief Description of the Drawings

[0037] Figure 1 This is the plan projection view of the twisted blade of the present invention; Figure 2 This is the layout diagram of the inlet section of the twisted blade of the present invention; Figure 3 This is the impeller model diagram of the centrifugal pump with twisted blades of the present invention; Figure 4 This is the sectional view of the twisted blade profile of the present invention; Figure 5 This is the comparison diagram of the prototype line and the fitted line of the embodiment of the present invention; Figure 6 This is the schematic diagram of the design method flow of the present invention. Detailed Description of the Invention

[0038] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature and not restrictive.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0041] In the present invention, unless otherwise clearly specified and defined, terms such as "mounted", "connected", "coupled", "fixed", etc. shall be construed broadly. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or a communication connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0043] It should be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of the described features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0044] It should also be understood that the terms used in the specification of the present invention are merely for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0045] It should be further understood that the term "and / or" used in the specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0046] Schematic diagrams of various structures according to the disclosed embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, where for the purpose of clear expression, certain details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art can additionally design regions / layers with different shapes, sizes, and relative positions according to actual requirements.

[0047] As Figure 6 shown, the present invention proposes a method for designing a twisted blade, including the following steps: Obtain dimensional parameters, twisted blade parameters, and centrifugal pump parameters; Establish a three-dimensional model based on the dimensional parameters, twisted blade parameters, and centrifugal pump parameters, and obtain the backbone curve of the twisted blade based on the three-dimensional model; Fit the backbone curve of the twisted blade to obtain the fitted backbone curve of the twisted blade; Determine the twisted blade based on the fitted backbone curve of the twisted blade.

[0048] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0049] Step 1. Obtain dimensional parameters In this embodiment, cavitation in the pump is mainly considered, so the correction coefficient is taken as 5; the inlet part of the blade is selected to be cylindrical. Considering that space needs to be left inside the hub for installing the rotating mechanism of the blade, the hub ratio is enlarged and selected. Therefore, the hub ratio is taken as 0.4. As Figure 2 shown, calculate the equivalent diameter at the inlet of the impeller and the hub diameter , and the calculation formulas are as follows:

[0050]

[0051]

[0052] In the formula: represents the correction coefficient, taken as 5; Q represents the flow rate, taken as 6 m 3 / h; represents the rotational speed, taken as 8000 r / min; represents the volumetric efficiency, taken as 0.95; represents the hub ratio, taken as 0.4.

[0053] Calculate the inlet diameter of the twisted blade to be 34 mm.

[0054] Specific speed of this embodiment n s Obtained by looking up the table, the correction coefficient is 19.73, is 1.94, and substitute into the following formula:

[0055]

[0056] In the formula: represents the correction coefficient, taking 19.73; represents the specific speed.

[0057]

[0058]

[0059] In the formula: represents the outlet width; represents the modification coefficient of the impeller outlet width; represents the correction coefficient. Through the above calculation, the impeller outlet diameter is 156 mm, and the outlet width is 4 mm.

[0060] Step 2: Obtain the parameters of the twisted blade In this embodiment, the circumferential speed based on the inlet diameter and the inlet meridional speed are used to calculate the shroud angle of the twisted blade, as shown in the following formula:

[0061]

[0062] In the formula: represents the circumferential speed of the inlet diameter; represents the inlet meridional speed of the inlet diameter; represents the blade blockage coefficient, taking 0.95; According to the above formula, the circumferential speed of the inlet diameter is calculated as: is 14.24 m / s, and the inlet meridional speed: is 2.4 m / s.

[0063] The shroud angle of the twisted blade is calculated and derived according to the following formula, specifically as follows:

[0064] In the formula: represents the relative flow angle of the shroud inlet diameter; represents the arctangent function.

[0065]

[0066] In the formula: represents the relative flow angle of the rim inlet diameter; represents the angle of attack, generally taken as 0° to 5°. In this embodiment, the relative flow angle of the rim inlet diameter is calculated to be 12°.

[0067]

[0068]

[0069] In the formula: represents the relative flow angle of the rim inlet diameter; represents the circumferential component of the absolute velocity at the outlet diameter; represents the acceleration due to gravity: represents the head, taken as 80; represents the circumferential velocity at the outlet diameter; represents the hydraulic efficiency.

[0070] In the formula: represents the blade angle at the rim outlet; represents the angle of attack, generally taken as 1° to 3°. In this embodiment, the blade angle at the rim outlet is calculated to be 15°.

[0071]

[0072] In the formula: represents the blade angle at the rim inlet; represents the average rim diameter; represents the average hub diameter. In this embodiment, the calculated value of the blade angle at the rim inlet is 21.8°.

[0073]

[0074] In the formula: represents the blade angle at the hub outlet. In this embodiment, the calculated value of the blade angle at the hub outlet is 32°.

[0075]

[0076] In the formula: represents the setting angle of the rim airfoil. In this embodiment, the calculated value of the setting angle of the rim airfoil is 12.5°.

[0077]

[0078] In the formula: Indicates the installation angle of the hub airfoil. In this embodiment, the calculated value of the installation angle of the hub airfoil is 26.5°.

[0079] Substitute the calculated value from the above formula into the following formula to calculate the wrap angle of the twisted blade rim, the wrap angle of the short blade rim, and the wrap angle of the short blade hub:

[0080]

[0081]

[0082] In the formula: Indicates the wrap angle of the twisted blade rim; Indicates the wrap angle of the short blade rim, Indicates the wrap angle of the short blade hub, Indicates the inlet sweep angle, taking 130°; Indicates the installation angle of the rim airfoil; Indicates the airfoil cascade density, taking 2; Indicates the number of twisted blades.

[0083] The calculated wrap angle of the short blade rim is 235°, the wrap angle of the short blade hub is 355°, the wrap angle of the twisted blade is 490°. The planar projection of the twisted blade is shown in Figure 1 , Figure 1 The wrap angle of the twisted blade rim in refers to the angle between the line connecting the inlet edge of the twisted blade and the center of the circle and the line connecting the outlet edge and the center of the circle.

[0084] In this embodiment, in order to prevent the occurrence of alternating blade cavitation, the number of twisted blades is generally set to an odd number. When the number of twisted blades and the number of main impeller blades are multiples of each other, it can increase the symmetry of the flow. The calculation is carried out according to the following formula:

[0085] In the formula: Indicates the total number of blades; Indicates the inlet diameter of the twisted blade; Indicates the outlet diameter of the impeller; Indicates the installation angle of the rim airfoil; Indicates the installation angle of the hub airfoil; sin represents the sine function.

[0086] Substitute the numerical values to calculate the total number of blades is 5.5. Here, 6 is taken. Therefore, the total number of blades is 6. Therefore, 3 twisted blades and 3 main blades are selected, and the twisted blades and the main blades are evenly distributed axially.

[0087] In the embodiment, the lead of the twisted blade inlet section refers to the helix length of the short blade from the inlet to the outlet, and an equal pitch design is adopted to ensure that the geometric parameters of the blade are consistent in the radial and axial directions. The calculation formula is as follows:

[0088] In the formula: represents the lead of the twisted blade inlet section; represents the average rim diameter; represents the setting angle of the airfoil section at the rim; represents the tangent function; in this embodiment, the lead of the twisted blade inlet section is calculated to be 24 mm.

[0089] In the embodiment, the pitch of the twisted blade inlet section refers to the helix pitch of the short blade in the axial direction. The calculation formula is as follows:

[0090] In the formula: represents the pitch of the twisted blade inlet section; in this embodiment, the pitch of the twisted blade inlet section is calculated to be 8 mm. In the embodiment, the axial distance on the hub side refers to the projected length of the short blade on the hub in the axial direction. The calculation formula is as follows:

[0091] In the formula: represents the axial distance on the hub side; in this embodiment, the axial distance on the hub side is calculated to be 15.47 mm.

[0092] In the embodiment, the axial distance on the rim side refers to the projected length of the short blade at the outer edge of the impeller in the axial direction. The calculation formula is as follows:

[0093] In the formula: represents the axial distance on the rim side. In this embodiment, the pitch of the twisted blade inlet section is calculated to be 23.37 mm. The specific layout schematic diagram is as shown in Figure 2 the figure.

[0094] Step 3: Establish a 3D model In this embodiment, based on the size parameters and twisted blade parameters obtained from the above calculations, and by selecting appropriate centrifugal pump parameters, a 3D model of the centrifugal pump is established using the CFturbo (CFturbo software&Engineering rotary machinery design software) software. In practical applications, considering the large blade wrap angle and high blade twist, a semi-open impeller is selected to improve the anti-blocking ability of the pump. The model schematic diagram is as shown in Figure 3 the figure.

[0095] Select a suitable perspective based on the 3D model diagram to generate a spatial blade profile diagram. Select a cross-section in the spatial blade profile diagram, find the backbone line in the cross-section, and connect the backbone line points of each cross-section to obtain the blade backbone line.

[0096] Step 4: Fit the blade backbone line Obtain the 3D coordinates of the blade backbone line through coordinate transformation; in this example, the blade is relatively twisted, so a second-order triangular polynomial is used to fit the blade backbone line in three segments, and the smooth connection of the curves is achieved by ensuring that each segment is tangent at the nodes. For the specific twisted blade profile and segmentation, see Figure 4 。

[0097] Second-order triangular polynomial model:

[0098]

[0099]

[0100] In the formula: represents a constant; represents the coefficient of the th cosine term; represents the coefficient of the th sine term; represents the polynomial degree; represents the index variable; represents the th discrete sampling point; and represent the order; represents the sine function.

[0101] The fitting results are as follows:

[0102] For the comparison diagram of the prototype line and the fitted line, see Figure 5 ,from Figure 5 it can be seen that the deviation between the fitted line obtained by the twisted blade design method of the present invention and the prototype line is small, which can provide a theoretical basis for the modification and optimization design of the blade.

[0103] In this embodiment, a centrifugal pump using the above-mentioned twisted blade is also provided. The foregoing has shown and described the basic principles, main features and advantages of the present invention. For a person skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes that fall within the meaning and scope of the equivalent elements of the claims in the present invention. Any reference signs in the claims should not be construed as limiting the claims concerned.

[0104] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. A person skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by a person skilled in the art. The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A method for designing a twisted blade, characterized in that, It includes the following steps: Obtain the size parameters, twisted blade parameters and centrifugal pump parameters; Establish a three-dimensional model based on the size parameters, twisted blade parameters and centrifugal pump parameters, and obtain the twisted blade backbone curve based on the three-dimensional model; Fit the twisted blade backbone curve to obtain the fitted twisted blade backbone curve; Determine the twisted blade based on the fitted twisted blade backbone curve.

2. The method for designing a twisted blade according to claim 1, wherein The size parameters include the equivalent diameter at the impeller inlet, hub diameter, twisted blade inlet diameter, impeller outlet diameter and outlet width; The calculation formula for the equivalent diameter at the impeller inlet is as follows: Wherein: represents the equivalent diameter at the impeller inlet, unit: mm; represents the correction coefficient, selected according to the actual project, unit: dimensionless; Q represents the flow rate, unit: m 3 / h; represents the rotational speed, unit: r / min; represents the volumetric efficiency, unit: dimensionless; The calculation formula for the hub diameter is as follows: In the formula: represents the hub ratio, which is determined according to the cross-sectional shape, unit: dimensionless; represents the hub diameter, unit: mm; The calculation formula for the twisted blade inlet diameter is as follows: In the formula: represents the inlet diameter of the twisted blade, unit: mm; The calculation formula for the impeller outlet diameter is as follows: In the formula: represents the impeller outlet diameter, unit: mm; represents the modification coefficient of the impeller outlet diameter, unit: dimensionless; represents the correction coefficient, determined according to the structure of the pump, unit: dimensionless; represents the specific speed, unit: dimensionless; The calculation formula for the outlet width is as follows: Wherein: represents the outlet width, unit: mm; represents the modification coefficient of the impeller outlet width, unit: dimensionless; represents the correction coefficient, unit: dimensionless.

3. The design method of a twisted blade according to claim 1, wherein The twisted blade parameters include the twisted blade rim wrap angle, short blade rim wrap angle, short blade hub wrap angle, total number of blades, twisted blade inlet section lead, twisted blade inlet section pitch, axial distance on the rim side and axial distance on the hub side; The calculation formula for the twisted blade rim wrap angle is as follows: In the formula: represents the wrap angle of the twisted blade rim, unit: °; represents the inlet sweep angle, taking 60° to 130°; represents the setting angle of the rim airfoil, unit: °; represents the airfoil cascade density, unit: dimensionless; represents the number of twisted blades, unit: pieces; represents the cosine function; The calculation formula for the short blade rim wrap angle is as follows: In the formula: represents the shroud angle of the short blade, unit: °; The calculation formula for the short blade hub wrap angle is as follows: In the formula: represents the hub included angle of the short blade, unit: °.

4. The design method of a twisted blade according to claim 3, characterized in that, The calculation formula for the twisted blade inlet section lead is as follows: In the formula: represents the lead of the twisted blade inlet section, unit: mm; represents the average rim diameter, unit: mm; represents the setting angle of the rim airfoil, unit: °; represents the tangent function; The calculation formula for the twisted blade inlet section pitch is as follows: In the formula: represents the pitch of the inlet section of the twisted blade, unit: mm; The calculation formula for the axial distance on the hub side is as follows: In the formula: represents the axial distance on the hub side, unit: mm; The calculation formula for the axial distance on the rim side is as follows: In the formula: represents the axial distance on the flange side, unit: mm.

5. The design method of a twisted blade according to claim 3, characterized in that Determine the total number of blades according to the rim airfoil setting angle; the total number of blades includes the number of twisted blades and the number of main impeller blades, where the number of twisted blades and the number of main impeller blades are set as multiples of each other, and the number of twisted blades is odd.

6. The design method of a twisted blade according to claim 5, characterized in that The calculation formula for the total number of blades is as follows: In the formula: represents the total number of blades, unit: piece; represents the inlet diameter of the twisted blade, unit: mm; represents the outlet diameter of the impeller, unit: mm; represents the setting angle of the rim airfoil, unit: °; represents the setting angle of the hub airfoil, unit: °; sin represents the sine function.

7. The method for designing a twisted blade according to claim 1, wherein Construct a three-dimensional model diagram through CFturbo software, draw the spatial blade profile diagram of the twisted blade according to the three-dimensional model diagram, and extract the blade backbone curve in the spatial blade profile diagram.

8. The design method of a twisted blade according to claim 1, characterized in that Use a second-order trigonometric polynomial to fit the twisted blade backbone curve, and the second-order trigonometric polynomial model is as follows: Wherein: represents a constant; represents the coefficient of the th-order cosine term; represents the coefficient of the th-order sine term; represents the th discrete sampling point; and represent the order; represents the sine function.

9. A twisted blade, characterized in that, The twisted blade is designed by the method according to any one of claims 1 to 8.

10. A centrifugal pump applying the twisted blade according to claim 9.

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