A twisted blade design method, twisted blade and application thereof

Abstract

The present application relates to the field of centrifugal pump design, in particular to a twisted blade design method, twisted blade and application thereof. Size parameters, twisted blade parameters and centrifugal pump parameters are obtained; a three-dimensional model is established according to the size parameters, twisted blade parameters and centrifugal pump parameters, and a twisted blade skeleton is obtained based on the three-dimensional model; the twisted blade skeleton is fitted to obtain a fitted twisted blade skeleton; and the twisted blade is determined based on the fitted twisted blade skeleton. The present application realizes twisted design of the blade by increasing the blade wrap angle, the blade is wound on the hub, the flow area is effectively increased, the flow guide effect can be realized, the working efficiency of the pump is improved, the installation of the inlet guide vane is saved by setting the inlet section, the axial size of the pump is effectively reduced, the structure of the centrifugal pump is more compact, and the maintenance cost of the centrifugal pump is reduced.

Description

Technical Field

[0001] This invention relates to the field of centrifugal pump design, specifically to a method for designing twisted blades, twisted blades, and their applications. Background Technology

[0002] Centrifugal pumps, widely used in industrial, agricultural, and municipal water supply systems, directly impact system efficiency and stability. However, centrifugal pumps are prone to cavitation when transporting liquids, especially at high speeds. Cavitation occurs when the local pressure of a liquid drops to its saturated vapor pressure, causing bubbles to form inside the pump and rapidly collapse. Cavitation not only reduces pump efficiency but also exacerbates vibration and noise, and in severe cases, can even damage the pump.

[0003] To improve the cavitation performance of centrifugal pumps, one common method is to improve the structural parameters of the pump inlet, specifically including the following measures: 1. Increasing the flow area at the pump inlet can reduce the liquid velocity and lower the risk of cavitation; 2. Increasing the radius of curvature of the impeller cover inlet section can improve the liquid flow state, thereby reducing the possibility of cavitation; 3. Reducing the blade inlet thickness can reduce the flow resistance of the liquid at the blade inlet, thus reducing cavitation; 4. Using a pre-inducing impeller, which can pre-pressurize the liquid before it enters the impeller, increasing the liquid pressure and reducing cavitation.

[0004] However, while these improvements have enhanced the cavitation performance of centrifugal pumps to some extent, they have also introduced some new problems. For example, improving the structural parameters of the pump inlet may lead to flow separation and the generation of eddies, thereby increasing hydraulic losses and noise and affecting the pump's operational stability. Using a front-mounted inducer increases the pump's structural complexity and 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 pressurize, resulting in reduced centrifugal pump efficiency and poor cavitation performance. Summary of the Invention

[0005] To address the problems mentioned in existing technologies, this invention proposes a twisted blade design method, twisted blades, and their applications. The twisted blade design is achieved by increasing the blade wrap angle. The twisted blades are wound around the hub, effectively increasing the flow area and improving pump efficiency. The blade inlet section is arranged with equal pitch to increase the fluid pressure at the inlet, reduce cavitation margin, and decrease the pump's axial dimensions, making the centrifugal pump structure more compact and reducing maintenance costs. Furthermore, the invention proposes using the least squares method and trigonometric polynomial fitting to regress the blade rib line, obtaining a fitting function expression for the blade rib line, which facilitates optimization and application in engineering practice.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention proposes a method for designing twisted blades, comprising the following steps:

[0008] Obtain dimensional parameters, twisted blade parameters, and centrifugal pump parameters;

[0009] A three-dimensional model is established based on the size parameters, twisted blade parameters, and centrifugal pump parameters. The twisted blade skeleton line is obtained based on the three-dimensional model.

[0010] Fit the rib line of the twisted blade to obtain the fitted rib line of the twisted blade;

[0011] The twisted blade is determined based on the fitted twisted blade bone line.

[0012] As a further improvement of the present invention, the dimensional parameters include the impeller inlet equivalent diameter, hub diameter, twisted blade inlet diameter, impeller outlet diameter, and outlet width;

[0013] The formula for calculating the equivalent diameter of the impeller inlet is as follows:

[0014]

[0015] In the formula: This indicates the equivalent diameter of the impeller inlet, in mm. The correction factor is selected based on the actual project; the unit is dimensionless. Q represents the flow rate; the unit is m³. 3 / h; Indicates rotational speed, unit: r / min; Volumetric efficiency, unit: dimensionless;

[0016] The formula for calculating the wheel hub diameter is as follows:

[0017]

[0018] In the formula: The hub ratio is determined based on the cross-sectional shape, and the unit is dimensionless. This indicates the hub diameter, in mm.

[0019] The formula for calculating the inlet diameter of the twisted blade is as follows:

[0020]

[0021] In the formula: This indicates the inlet diameter of the twisted blade, in mm.

[0022] The formula for calculating the impeller outlet diameter is as follows:

[0023]

[0024]

[0025] In the formula: Indicates the impeller outlet diameter, in mm; The modification factor for the impeller outlet diameter, in dimensionless form; This represents a correction factor, which depends on the pump's structure. The unit is dimensionless. Specific rotational speed, unit: dimensionless;

[0026] The formula for calculating the outlet width is as follows:

[0027]

[0028]

[0029] In the formula: Indicates the width of the outlet, in mm; The modification factor for the impeller outlet width, in dimensionless form; This represents the correction factor, in dimensionless form.

[0030] As a further improvement of the present invention, the twisted blade parameters include the twisted blade rim wrap angle, the short blade rim wrap angle, the short blade hub wrap angle, the total number of blades, the twisted blade inlet section lead, the twisted blade inlet section pitch, the axial distance on the rim side, and the axial distance on the hub side.

[0031] The formula for calculating the wrap angle of a twisted blade rim is as follows:

[0032]

[0033] In the formula: Indicates the wrap angle of the twisted blade rim, in degrees (°). This indicates the inlet sweep angle, ranging from 60° to 130°. Indicates the airfoil mounting angle, unit: °; This represents the density of the airfoil cascade, in dimensionless form. This indicates the number of twisted blades, in units of: individual blades. Represents the cosine function;

[0034] The formula for calculating the rim wrap angle of a short blade is as follows:

[0035]

[0036] In the formula: Indicates the rim wrap angle of the short blade, in degrees (°).

[0037] The formula for calculating the hub wrap angle of a short-blade wheel is as follows:

[0038]

[0039] In the formula: This indicates the hub wrap angle for short blades, in degrees.

[0040] As a further improvement to the present invention, the formula for calculating the lead of the inlet section of the twisted blade is as follows:

[0041]

[0042] In the formula: This indicates the lead of the inlet section of the twisted blade, in mm. This represents the average rim diameter, in mm. Indicates the airfoil mounting angle, unit: °; Represents the tangent function;

[0043] The formula for calculating the pitch of the inlet section of the twisted blade is as follows:

[0044]

[0045] In the formula: This indicates the pitch of the inlet section of the twisted blade, in mm.

[0046] The formula for calculating the axial distance on the hub side is as follows:

[0047]

[0048] In the formula: Indicates the axial distance on the hub side, in mm;

[0049] The formula for calculating the axial distance on the rim side is as follows:

[0050]

[0051] In the formula: This indicates the axial distance on the rim side, in mm.

[0052] As a further improvement of the present invention, the total number of blades is determined according to the airfoil placement angle of the rim; 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 an odd number.

[0053] As a further improvement to the present invention, the formula for calculating the total number of blades is as follows:

[0054]

[0055] In the formula: This indicates the total number of blades, in units of: blades; This indicates the inlet diameter of the twisted blade, in mm. Indicates the impeller outlet diameter, in mm; Indicates the airfoil mounting angle, unit: °; The value represents the hub airfoil placement angle, in degrees; sin represents the sine function.

[0056] As a further improvement of the present invention, a three-dimensional model diagram is constructed using CFturbo software, and a spatial blade profile diagram of the twisted blade is drawn based on the three-dimensional model diagram. The blade rib lines in the spatial blade profile diagram are then extracted.

[0057] As a further improvement to the present invention, a second-order trigonometric polynomial is used to fit the rib line of the tortuous blade. The second-order trigonometric polynomial model is as follows:

[0058]

[0059]

[0060]

[0061] In the formula: Represents a constant; Indicates the first The coefficients of the cosine term; Indicates the first The coefficient of the first-order sine term; Indicates the degree of the polynomial; Indicates an index variable; Indicates the first A discrete sampling point; and Indicates the order; This represents the sine function.

[0062] Secondly, the present invention proposes a twisted blade, which is designed by the above-described method.

[0063] Thirdly, the present invention proposes a centrifugal pump that utilizes the aforementioned twisted blades.

[0064] Compared with the prior art, the present invention achieves the following technical effects:

[0065] The blade design method provided by this invention aims to improve the cavitation performance of the pump. It calculates the blade rim wrap angle using multiple parameters, resulting in a twisted blade structure wound around the hub. This effectively increases the flow area and improves pump efficiency. By arranging the blade inlet section with equal pitch, the inlet fluid pressure is increased, cavitation margin is reduced, and the pump's axial dimensions are decreased, making the centrifugal pump structure more compact and reducing maintenance costs. Based on the least squares principle, a trigonometric polynomial fitting method is used to perform regression analysis on the blade rib line, achieving a precise description of the blade geometry. This invention provides a theoretical basis for blade modification and optimization design, enabling rapid and accurate adjustment of blade parameters to further improve pump performance.

[0066] The twisted blades designed in this invention feature a large wrap angle and a small angle of attack, which can effectively reduce the pressure drop when the liquid working fluid flows around the blade profile, reduce flow loss, and thus improve the fluid efficiency and energy conversion efficiency of the centrifugal pump.

[0067] The twisted blades wrapped around the hub significantly increase the flow area, achieving good flow guidance and improving the pump's fluid dynamics performance. At the same time, the centrifugal force is small, and the liquid working medium is less prone to gas-liquid separation during flow, effectively improving the cavitation performance of the centrifugal pump and extending the pump's service life.

[0068] To ensure a uniform radial velocity distribution along the axial surface of the inlet region, an equal pitch arrangement is adopted for the inlet section of the twisted blades, effectively avoiding flow losses caused by uneven velocity distribution and further optimizing the inlet flow conditions of the pump. At the same time, a high blade density is set in the blade inlet section, so that the maximum pressure drop point is located in the outer edge region of the blade, which is far from the blade inlet and has higher fluid pressure, reducing the critical effective cavitation margin. The inlet section eliminates the need for inlet guide vanes in traditional centrifugal pumps, which not only effectively reduces the axial distance but also makes the overall structure of the centrifugal pump more compact, reducing manufacturing costs and installation difficulty. Attached Figure Description

[0069] Figure 1 This is a planar projection view of the twisted blade of the present invention;

[0070] Figure 2 This is a diagram showing the arrangement of the inlet section of the twisted blade of the present invention;

[0071] Figure 3 This is a model diagram of the centrifugal pump impeller with twisted blades according to the present invention;

[0072] Figure 4 This is an explanatory diagram of the segmented profile of the twisted blade of the present invention;

[0073] Figure 5 This is a comparison diagram of the prototype line and the fitted line in an embodiment of the present invention;

[0074] Figure 6 This is a schematic diagram of the design method of the present invention. Detailed Implementation

[0075] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0076] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0077] Furthermore, 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 number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0078] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0079] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0080] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0081] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0082] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0083] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0084] like Figure 6 As shown, this invention proposes a method for designing twisted blades, comprising the following steps:

[0085] Obtain dimensional parameters, twisted blade parameters, and centrifugal pump parameters;

[0086] A three-dimensional model is established based on the size parameters, twisted blade parameters, and centrifugal pump parameters. The twisted blade skeleton line is obtained based on the three-dimensional model.

[0087] Fit the rib line of the twisted blade to obtain the fitted rib line of the twisted blade;

[0088] The twisted blade is determined based on the fitted twisted blade bone line.

[0089] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0090] Step 1: Obtain Dimension Parameters

[0091] This embodiment primarily considers cavitation within the pump, therefore the correction factor... A value of 5 is chosen; the blade inlet section is cylindrical. Considering the need to leave space inside the hub for installing the blade rotation mechanism, the hub ratio is enlarged and selected accordingly. Therefore, the hub ratio is... Take 0.4, such as Figure 2 As shown, calculate the equivalent diameter of the impeller inlet. and hub diameter The calculation formula is as follows:

[0092]

[0093]

[0094]

[0095] In the formula: The correction factor is 5; Q represents the flow rate, which is 6m³. 3 / h; This indicates the rotational speed, taken as 8000 r / min; This represents the volumetric efficiency, taken as 0.95. This indicates the hub ratio, which is set to 0.4.

[0096] Calculate the inlet diameter of the twisted blade It is 34mm.

[0097] Specific speed in this embodiment n s The correction factor is obtained from the table. It is 19.73. The value is 1.94. Substituting this into the following formula:

[0098]

[0099]

[0100] In the formula: This represents the correction factor, which is set to 19.73. This indicates the specific speed.

[0101]

[0102]

[0103] In the formula: Indicates the width of the outlet; This represents the modification factor for the impeller outlet width; This represents the correction factor.

[0104] The impeller outlet diameter is obtained from the above calculations. It is 156mm wide at the outlet. It is 4mm.

[0105] Step 2: Obtain the parameters of the twisted blades

[0106] This embodiment calculates the wrap angle of the twisted blade rim based on the circumferential velocity and the axial velocity of the inlet diameter, as shown in the following formula:

[0107]

[0108]

[0109] In the formula: The circumferential velocity representing the inlet diameter; The inlet shaft surface velocity represents the inlet diameter; This represents the blade rejection coefficient, taken as 0.95;

[0110] The circumferential velocity of the inlet diameter can be calculated using the above formula: The inlet shaft surface velocity is 14.24 m / s. It is 2.4 m / s.

[0111] The wrap angle of the twisted blade rim is derived and calculated using the following formula, as follows:

[0112]

[0113] In the formula: Indicates the angle between the rim inlet diameter and the fluid flow angle; This represents the arctangent function.

[0114]

[0115] In the formula: Indicates the angle between the rim inlet diameter and the fluid flow angle; The angle of attack is typically taken as 0° to 5°. This embodiment calculates the angle between the rim inlet diameter and the fluid flow angle. The value is 12°.

[0116]

[0117]

[0118] In the formula: Indicates the angle between the rim inlet diameter and the fluid flow angle; The circumferential component representing the absolute velocity of the outlet diameter; Represents gravitational acceleration: To indicate head, take 80; The circumferential velocity representing the outlet diameter; Indicates hydraulic efficiency.

[0119]

[0120] In the formula: Indicates the rim exit blade angle; The angle of attack is typically taken as 1° to 3°. This embodiment calculates the rim exit blade angle. The value is 15°.

[0121]

[0122] In the formula: Indicates the inlet blade angle of the rim; Indicates the average rim diameter; This represents the average hub diameter. In this embodiment, the calculated inlet blade angle at the rim is 21.8°.

[0123]

[0124] In the formula: This indicates the hub exit blade angle. In this embodiment, the hub exit blade angle is calculated to be 32°.

[0125]

[0126] In the formula: This indicates the rim airfoil placement angle. In this embodiment, the calculated rim airfoil placement angle is 12.5°.

[0127]

[0128] In the formula: This indicates the hub airfoil placement angle. In this embodiment, the calculated hub airfoil placement angle is 26.5°.

[0129] Substituting the calculated values ​​from the above formula into the following formula, we can obtain the twisted blade rim wrap angle, the short blade rim wrap angle, and the short blade hub wrap angle:

[0130]

[0131]

[0132]

[0133] In the formula: Indicates the wrap angle of the twisted blade rim; Indicates the rim wrap angle of the short blade. Indicates the hub wrap angle of the short blade. This indicates the inlet sweep angle, taken as 130°; Indicates the rim airfoil placement angle; This represents the airfoil cascade density, taken as 2; This indicates the number of twisted blades.

[0134] The calculated rim wrap angle of the short blade The hub wrap angle is 235°, with short blades. The twisted blade wrap angle is 355°. The angle is 490°, and the plane projection of the twisted blade is shown in the image. Figure 1 , Figure 1 The rim wrap angle of the twisted blade This refers to the angle between the line connecting the inlet edge of the twisted blade to the center of the circle and the line connecting the outlet edge to the center of the circle.

[0135] In this embodiment, to prevent 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, the symmetry of the flow can be increased. The calculation is performed according to the following formula:

[0136]

[0137] In the formula: Indicates the total number of blades; Indicates the inlet diameter of the twisted blade; Indicates the impeller outlet diameter; Indicates the rim airfoil placement angle; The angle of the hub airfoil is represented by ; sin represents the sine function.

[0138] Substitute the numerical values ​​to obtain the total number of blades. The value is 5.5, but we take 6 here, so the total number of blades is 6. Therefore, we choose twisted blades. There are 3 main blades and 3 twisted blades, and the twisted blades are evenly distributed along the axis of the main blades.

[0139] In this embodiment, the lead of the inlet section of the twisted blade refers to the helix length of the short blade from the inlet to the outlet. A constant pitch design is adopted to ensure that the geometric parameters of the blade remain consistent in the radial and axial directions. The calculation formula is as follows:

[0140]

[0141] In the formula: Indicates the lead of the inlet section of the twisted blade; Indicates the average rim diameter; Indicates the airfoil placement angle on the rim section; This represents the tangent function; in this embodiment, the lead of the inlet section of the twisted blade is calculated to be 24 mm.

[0142] In this embodiment, the pitch of the inlet section of the twisted blade refers to the spacing between the helical lines of the short blades along the axial direction, and the calculation formula is as follows:

[0143]

[0144] In the formula: The pitch of the inlet section of the twisted blade is indicated; in this embodiment, the pitch of the inlet section of the twisted blade is calculated to be 8 mm.

[0145] In this embodiment, the axial distance on the hub side refers to the projected length of the short blade on the hub in the axial direction, and the calculation formula is as follows:

[0146]

[0147] In the formula: This indicates the axial distance on the hub side; in this embodiment, the calculated axial distance on the hub side is 15.47mm.

[0148] In this embodiment, the axial distance on the impeller rim side refers to the projected length of the short blade at the outer edge of the impeller in the axial direction, and the calculation formula is as follows:

[0149]

[0150] In the formula: This indicates the axial distance on the rim side. In this embodiment, the pitch of the inlet section of the twisted blade is calculated to be 23.37 mm. A detailed layout diagram is shown below. Figure 2 As shown.

[0151] Step 3: Create a 3D model

[0152] This embodiment uses the calculated dimensional parameters and twisted blade parameters, along with appropriate centrifugal pump parameters, to create a 3D model of the centrifugal pump using CFturbo (CFturbo software & Engineering rotating machinery design software). In practical applications, considering the large blade wrap angle and high blade twist, a semi-open impeller is selected to improve the pump's anti-clogging capability. A schematic diagram of the model is shown below. Figure 3 As shown.

[0153] Based on the 3D model diagram, select an appropriate perspective to generate a spatial blade profile diagram. Select a section in the spatial blade profile diagram, find the rib line in the section, and connect the rib line points of each section to obtain the blade rib line.

[0154] Step 4: Fitting leaf skeletal lines

[0155] The three-dimensional coordinates of the blade rib line are obtained through coordinate transformation. In this example, the blade is quite twisted, so a second-order trigonometric polynomial is used to fit the blade rib line in three segments. By ensuring that each segment is tangent at the nodes, the curve is smoothly connected. For details on the twisted blade profile and segmentation, see [link to documentation]. Figure 4 .

[0156] Second-order trigonometric polynomial model:

[0157]

[0158]

[0159]

[0160] In the formula: Represents a constant; Indicates the first The coefficients of the cosine term; Indicates the first The coefficient of the first-order sine term; Indicates the degree of the polynomial; Indicates an index variable; Indicates the first A discrete sampling point; and Indicates the order; This represents the sine function.

[0161] The fitting results are as follows:

[0162]

[0163] See the comparison chart of the prototype line and the fitted line. Figure 5 ,from Figure 5 As can be seen from the present invention, the fitting profile obtained by the twisted blade design method has a small deviation from the prototype profile, which can provide a theoretical basis for the modification and optimization design of blades.

[0164] This embodiment also provides a centrifugal pump using the aforementioned twisted blades.

[0165] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0166] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for designing twisted blades, characterized in that, Includes the following steps: Obtain dimensional parameters, twisted blade parameters, and centrifugal pump parameters; the twisted blade parameters include the twisted blade rim wrap angle, the short blade rim wrap angle, the short blade hub wrap angle, the total number of blades, the twisted blade inlet section lead, the twisted blade inlet section pitch, the axial distance on the rim side, and the axial distance on the hub side. The formula for calculating the wrap angle of a twisted blade rim is as follows: In the formula: Indicates the wrap angle of the twisted blade rim, in degrees (°). This indicates the inlet sweep angle, ranging from 60° to 130°. Indicates the airfoil mounting angle, unit: °; This represents the density of the airfoil cascade, in dimensionless form. This indicates the number of twisted blades, in units of: individual blades. Represents the cosine function; The formula for calculating the rim wrap angle of short blades is as follows: In the formula: Indicates the rim wrap angle of the short blade, in degrees (°). The formula for calculating the hub wrap angle of a short-blade wheel is as follows: In the formula: Indicates the hub wrap angle for short blades, in degrees; The formula for calculating the lead of the inlet section of the twisted blade is as follows: In the formula: This indicates the lead of the inlet section of the twisted blade, in mm. This represents the average rim diameter, in mm. Indicates the airfoil mounting angle, unit: °; Represents the tangent function; The formula for calculating the pitch of the inlet section of the twisted blade is as follows: In the formula: This indicates the pitch of the inlet section of the twisted blade, in mm. The formula for calculating the axial distance on the hub side is as follows: In the formula: Indicates the axial distance on the hub side, in mm; The formula for calculating the axial distance on the rim side is as follows: In the formula: This indicates the axial distance on the rim side, in mm. The total number of blades is determined based on the airfoil placement angle of the rim; 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 an odd number; The formula for calculating the total number of blades is as follows: In the formula: This indicates the total number of blades, in units of: blades; This indicates the inlet diameter of the twisted blade, in mm. Indicates the impeller outlet diameter, in mm; Indicates the airfoil mounting angle, unit: °; The hub airfoil placement angle is expressed in degrees; sin represents the sine function. A three-dimensional model is established based on the size parameters, twisted blade parameters, and centrifugal pump parameters. The twisted blade skeleton line is obtained based on the three-dimensional model. Fit the rib line of the twisted blade to obtain the fitted rib line of the twisted blade; The twisted blade is determined based on the fitted twisted blade bone line.

2. The twisted blade design method according to claim 1, characterized in that, The dimensional parameters include the impeller inlet equivalent diameter, hub diameter, twisted blade inlet diameter, impeller outlet diameter, and outlet width; The formula for calculating the equivalent diameter of the impeller inlet is as follows: In the formula: This indicates the equivalent diameter of the impeller inlet, in mm. This represents the correction factor, selected based on the actual project; unit: dimensionless. Q represents flow rate, in meters (m). 3 / h; Indicates rotational speed, unit: r / min; Volumetric efficiency, unit: dimensionless; The formula for calculating the wheel hub diameter is as follows: In the formula: The hub ratio is determined based on the cross-sectional shape, and the unit is dimensionless. This indicates the hub diameter, in mm. The formula for calculating the inlet diameter of the twisted blade is as follows: In the formula: This indicates the inlet diameter of the twisted blade, in mm. The formula for calculating the impeller outlet diameter is as follows: In the formula: Indicates the impeller outlet diameter, in mm; The modification factor for the impeller outlet diameter, in dimensionless form; This represents a correction factor, which depends on the pump's structure, and is in dimensionless form. Specific rotational speed, unit: dimensionless; The formula for calculating the outlet width is as follows: In the formula: Indicates the width of the outlet, in mm; The modification factor for the impeller outlet width, in dimensionless form; This represents the correction factor, in dimensionless form.

3. The twisted blade design method according to claim 1, characterized in that, A three-dimensional model was constructed using CFturbo software. Based on the three-dimensional model, a spatial blade profile of the twisted blade was drawn, and the blade rib lines were extracted from the spatial blade profile.

4. The twisted blade design method according to claim 1, characterized in that, The tortuous blade bone line is fitted using a second-order trigonometric polynomial, and the second-order trigonometric polynomial model is as follows: In the formula: Represents a constant; Indicates the first The coefficients of the cosine term; Indicates the first The coefficient of the first-order sine term; Indicates the degree of the polynomial; Indicates an index variable; Indicates the first A discrete sampling point; and Indicates the order; This represents the sine function.

5. A twisted blade, characterized in that, The twisted blade is designed by the method described in any one of claims 1 to 4.

6. A centrifugal pump employing the twisted blades of claim 5.

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