Design method of long-short split blade impeller based on s-shaped short blade and water pump
By introducing S-shaped design and Hermite curve construction method into the short-blade impeller, the unfavorable flow problem in the short-blade channel was solved, and the effective control of fluid flow and improvement of pump efficiency were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TSINGHUA UNIVERSITY
- Filing Date
- 2026-02-27
- Publication Date
- 2026-06-09
Smart Images
Figure CN122170094A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of vane pump technology, and in particular to a design method for a long and short split-flow impeller based on S-shaped short blades and a water pump. Background Technology
[0002] In recent years, the non-uniformity and complex three-dimensional effects within the flow channels of water pumps have become increasingly pronounced. This is particularly evident in impellers with both long and short blades, where the local pressure gradient within the short blade channels is often large, easily inducing unfavorable flow phenomena such as wake vortices, thus affecting overall energy transfer efficiency. In related technologies, existing short blades typically maintain a fixed backward-curved structure, with their profile exhibiting relatively uniform radial variation, making it difficult to effectively control the flow while ensuring a stable outlet flow direction. Summary of the Invention
[0003] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to propose a design method for a long-short split-flow impeller based on S-shaped short blades, aiming to solve the problem of unfavorable flow phenomena easily generated within the short blade channel of the impeller, making it difficult to effectively control fluid flow.
[0004] In a first aspect, this invention proposes a design method for a long-short split-flow impeller based on S-shaped short blades. The long-short split-flow impeller includes a hub, several long blades, and several short blades. Both the long and short blades include a pressure surface and a suction surface. The short blades are S-shaped and include an inlet section, a middle section, and an outlet section. The shape of the middle section is determined by a cubic Hermite basis function. One end of the middle section smoothly transitions to the inlet section, and the other end of the middle section smoothly transitions to the outlet section. The design outline of the short blades is provided. C ( r The expression for ) is:
[0005]
[0006] In the formula, C 0( r () represents the original outline. H ( t ( r )) represents the Hermite curve. R ( i ) is a rotation matrix. r a This represents the starting radial position of the middle section. r b This represents the initial radial position of the exit section. r c This refers to the radial position of the end point of the exit section. t ( r() is a radial parameter mapping function used to map physical radial coordinates. r Normalize to the dimensionless interval [0,1]. t ( r The formula for ) is:
[0007] According to some embodiments of the first aspect of the present invention, the design method of a long and short split-flow blade impeller based on an S-shaped short blade includes the following steps: determining a first design profile of the inlet section of the short blade and a second design profile of the outlet section of the short blade; constructing a third design profile of the middle section of the short blade using Hermite curves based on the first and second design profiles; and generating a complete design profile of the short blade according to the first, second, and third design profiles.
[0008] According to some embodiments of the first aspect of the present invention, determining a first design profile and a second design profile includes: obtaining an original profile of a short blade, the original profile including a first original profile of an inlet section and a second original profile of an outlet section; using the first original profile as the first design profile; and rotating the second original profile about the axis of the impeller by an angle. i Then, the second design outline is obtained.
[0009] According to some embodiments of the first aspect of the present invention, obtaining the original profile of a short blade includes: obtaining the profile features of a long blade, the profile features including blade shape features and leading edge features, the blade shape features including the distribution of the mid-curve, thickness distribution, and the variation law of the installation angle, and the leading edge features including the leading edge rounding radius and the leading edge rounding form; selecting a long blade at 0.8... R~R The leaf shape features within the radial interval are used as the original outline leaf shape features of the short leaf, where, R The impeller outlet radius is defined; the leading edge features of the long blades are selected as the original profile leading edge features of the short blades; the original profile of the short blades is generated based on the original profile airfoil features and the original profile leading edge features of the short blades.
[0010] According to some embodiments of the first aspect of the present invention, determining a first design profile for the short blade inlet section and a second design profile for the short blade outlet section, and constructing a third design profile for the intermediate section using Hermite curves based on the first and second design profiles, includes: determining a first suction surface profile and a first pressure surface profile for the short blade inlet section, the first suction surface profile and the first pressure surface profile constituting the first design profile; determining a second suction surface profile and a second pressure surface profile for the short blade outlet section, the second suction surface profile and the second pressure surface profile constituting the second design profile; constructing a third suction surface profile for the short blade intermediate section using Hermite curves based on the first suction surface profile and the second suction surface profile; constructing a third pressure surface profile for the intermediate section using Hermite curves based on the first pressure surface profile and the second pressure surface profile; the third suction surface profile and the third pressure surface profile constituting the third design profile.
[0011] According to some embodiments of the first aspect of the invention, the rotation matrix R ( i The formula for ) is: .
[0012] According to some embodiments of the first aspect of the present invention, the formula for the Hermite curve is:
[0013] In the formula, H PS ( t ( r ))and H SS ( t ( r These are the cubic Hermite forms of the third pressure surface profile and the third suction surface profile of the short blade, respectively, and the specific formulas are as follows:
[0014] In the formula, h 0( t ) 、h 1( t ) 、h 2( t ) 、h 3( t ) are cubic Hermite basis functions; C P0 ( r a () represents the starting coordinates of the profile of the third pressure surface of the short blade; R ( i ) CP0 ( r b () represents the endpoint coordinates of the third pressure surface profile of the short blade; C S0 ( r a () represents the starting coordinates of the profile of the third suction surface of the short blade; R ( i ) C S0 ( r b () represents the coordinates of the endpoint of the profile of the third suction surface of the short blade; M P0 ( r a () is an approximation of the starting tangent vector of the profile of the third pressure surface of the short blade; R ( i ) M P0 ( r b () is an approximation of the endpoint tangent vector of the profile of the third pressure surface of the short blade; M S0 ( r a () is an approximation of the starting tangent vector of the profile of the third suction surface of the short blade; R ( i ) M S0 ( r b ) is an approximation of the endpoint tangent vector of the profile of the third suction surface of the short blade.
[0015] According to some embodiments of the first aspect of the present invention, the formulas for the Hermite basis functions are as follows:
[0016] According to some embodiments of the first aspect of the present invention, the approximate calculation formula for the starting tangent vector of the profile of the third pressure surface of the short blade is as follows:
[0017] The approximate formula for calculating the endpoint tangent vector of the third pressure surface profile of the short blade is as follows:
[0018] The approximate formula for calculating the starting tangent vector of the profile of the third suction surface of the short blade is as follows:
[0019] The approximate formula for calculating the endpoint tangent vector of the third suction surface profile of the short blade is as follows:
[0020] In the formula, d 11 , d 21 , d 12 , d 22 Both represent tiny parameter increments along the corresponding contour curve parameter direction, used to perform a first-order difference approximation of the tangential direction of the contour curve at the start or end point; in the specific implementation, the parameter increment corresponds to the adjacent step size between discrete sampling points of the contour line, and its positive or negative direction is determined by the calculation position of the tangential vector; when the contour line is represented by a series of discrete coordinate points, the above difference operation is equivalent to the vector difference between adjacent coordinate points.
[0021] Secondly, the present invention proposes a water pump, including an impeller, which is obtained by adopting the above-mentioned design method of long and short split-flow blade impeller based on S-shaped short blades.
[0022] This invention introduces a triple Hermite parametric smooth connection segment in the middle section of the short blade, achieving continuous, smooth, and controllable curvature geometry of the actual profile of the short blade throughout the entire design range. This avoids the abrupt changes in inflection points and curvature discontinuities caused by traditional geometric splicing methods, enabling controlled geometric adjustment of the short blade in the middle section. It also allows for curvature control of the pressure and suction surfaces in the rear section of the short blade in localized areas, thereby improving the fluid rotation angle and velocity field distribution within the flow channel, enhancing the flow stability of the blade channel, and significantly optimizing the hydrodynamic performance and operating efficiency of the pump.
[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of an impeller obtained by a design method for long and short split-flow blades based on S-shaped short blades according to an embodiment of the present invention.
[0025] Figure 2 This is a schematic diagram of the profile of a short blade according to an embodiment of the present invention.
[0026] Figure 3 This is a schematic diagram comparing the design outline of a short blade with the original outline according to an embodiment of the present invention.
[0027] Figure label: Import section 10; intermediate section 20; export section 30; Short blade 100; suction surface 101; pressure surface 102; long blade 200; hub 300. Detailed Implementation
[0028] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0029] The following is for reference. Figure 1-Figure 3 This invention describes a method for designing long and short split-flow blade impellers based on S-shaped short blades according to embodiments of the present invention.
[0030] The long and short split-blade impeller includes a hub, multiple long blades, and multiple short blades, with the long and short blades arranged alternately along the circumference of the hub. As mentioned in the background section, due to the profile of existing short blades, the local pressure gradient within the short blade channel is often large, easily inducing unfavorable flow phenomena such as wake vortices, thus affecting the overall energy transfer efficiency. Furthermore, existing short blades typically maintain a fixed backward-curved structure, and their profile changes relatively uniformly along the radial direction, making it difficult to effectively control the flow while ensuring a stable outlet flow direction.
[0031] To improve pressure distribution within the short-blade channel, this invention proposes a design method for a long-short split-flow impeller based on S-shaped short blades, enabling gentle and controllable adjustment of the short blade geometry in localized areas. The long-short split-flow impeller of this invention is as follows: Figure 1 As shown, the short blade 100 has an S-shaped structure, comprising an inlet section 10, a middle section 20, and an outlet section 30. The shape of the middle section 20 is determined by a cubic Hermite basis function. One end of the middle section 20 smoothly transitions to the inlet section 10, and the other end of the middle section 20 smoothly transitions to the outlet section 30. The design outline of the short blade 100 is shown. C ( r The formula for calculating ) is:
[0032] In the formula, C 0( r () represents the original outline. H ( t ( r )) represents the Hermite curve. r a This is the starting radial position of the middle section 20. r b This is the starting radial position of the exit section 30. rc This refers to the radial position of the end point of the exit section 30. t ( r () is a radial parameter mapping function used to map physical radial coordinates. r Normalize to the dimensionless interval [0,1]. t ( r The formula for ) is:
[0033] R ( i ) is a rotation matrix. The formula is:
[0034] R ( i ) C 0( r The original outline rotates around the impeller axis O. i The contour line obtained after angling.
[0035] The actual profile of the short blade 100 C ( r ) by its original outline C 0( r Hermite curve H ( t ( r and rotation matrix R ( i They are generated together.
[0036] The design method for long and short split-flow impellers based on S-shaped short blades specifically includes the following steps: S1. Determine the first design profile of the short blade inlet section 10 and the second design profile of the short blade outlet section 30. The shape of the inlet section 10 of the short blade 100 directly affects the initial conditions of the fluid entering the blade channel, such as velocity, angle, and pressure distribution. A reasonable first design profile can reduce flow separation, reduce turbulence, and ensure that the fluid impacts the blade at the optimal angle, thereby improving efficiency and reducing energy loss. The outlet section 30 of the short blade 100 ensures that the fluid leaves the blade smoothly. A reasonable second design profile can control the fluid discharge direction, reduce wake loss, and maintain the stability of the downstream flow field by optimizing the outlet angle and profile. In the short blade 100 design method of the present invention, step S1 first determines the first design profile of the inlet section 10 of the short blade 100 and the second design profile of the outlet section 30 of the short blade 100. This can establish a design basis for the design process of the intermediate section 20 of the short blade 100 and control the design of the overall profile of the short blade 100.
[0037] According to some embodiments of the present invention, determining a first design profile and a second design profile includes: S1.1 Obtain the original profile of the short blade 100, the original profile including the first original profile of the inlet section 10 and the second original profile of the outlet section 30; S1.2 The first original contour is used as the first design contour; S1.3 Rotate the second original profile around the axis O of the hub 300 by a preset angle. i Then, the second design outline is obtained.
[0038] As described in the background section, the existing short blades 100 employ a single radial variation design for their profiles, maintaining a fixed backward curve structure, making it difficult to effectively control the flow while ensuring a stable outlet flow direction. To address this technical limitation, this embodiment retains the original profile of the inlet section 10 as the first design profile based on the original short blade 100 profile, and adjusts the original profile of the outlet section 30 by rotation and displacement to form the second design profile.
[0039] According to some embodiments of the present invention, the design method of long and short split-flow blade impeller based on S-shaped short blades further includes: determining the target load distribution law of the long blade 200 according to the design conditions and performance targets of the long and short split-flow blade impeller; and determining the profile of the long blade 200 according to the target load distribution law.
[0040] Further, according to some embodiments of the present invention, obtaining the original profile of the short blade 100 includes: determining the radial distribution range of the short blade 100 in the long and short splitter blade impeller; obtaining the profile features of the long blade 200 in the radial distribution range; and using the profile features of the long blade 200 in the radial distribution range as the original profile features of the short blade 100 to obtain the original profile of the short blade 100.
[0041] Specifically, obtaining the original outline of the short blade 100 includes: obtaining the outline features of the long blade 200, wherein the outline features include blade shape features and leading edge features, the blade shape features include the distribution of the mid-curve, thickness distribution, and the variation law of the installation angle, etc., and the leading edge features include the leading edge rounding radius and the leading edge rounding form, etc.; selecting the long blade 200 at 0.8 R ~ R The leaf shape features within the radial interval are used as the original outline leaf shape features of the short leaf 100; among them, R The impeller outlet radius is used; the leading edge feature of the long blade 200 is selected as the original profile leading edge feature of the short blade 100; based on the original profile airfoil feature and the original profile leading edge feature of the short blade 100, the original profile of the short blade 100 is generated. When designing the short blade 100, the outlet radius of the long and short split impeller blades is used first.R As a geometric reference, the short blade 100 is arranged at 0.8. R~R Within the radial interval, the radial position of the end point of the outlet section 30 r c That is, the radius is R The radial position of the short blade 100, its spanwise length, and its radial position are all strictly controlled; to ensure the geometric continuity of the impeller passage and the consistency of flow characteristics, the short blade 100 is positioned at 0.8... R The blade is geometrically aligned with the long blade at 200mm, and its leaf shape parameter is 0.8. R~R The blade profile parameters of the section corresponding to the long blade 200 within the interval are completely consistent, including the distribution of arc lines, thickness distribution, and installation angle variation patterns within the blade. Furthermore, the leading edge (head) of the short blade 100 adopts the same rounding radius and rounding form as the long blade 200 to avoid flow separation or additional losses caused by local geometric abrupt changes. By determining the geometry of the short blade 100 in the above manner, the consistency of the exit passage structure can be maintained while introducing the regulating effect of the long and short blade combination on flow and vibration characteristics.
[0042] In some embodiments, step S1.3 specifically includes: rotating the second original profile around the impeller axis O along the impeller rotation direction by an angle. i .like Figure 3 As shown, in this embodiment, the second original contour is rotated by an angle around the impeller axis O along the impeller rotation direction. i Without changing the tilt direction of the outlet section 30, an S-shaped section can be formed in the middle of the short blade 100 to obtain the middle section 20, thereby achieving the technical effect of improving the pressure gradient distribution.
[0043] S2. Based on the endpoint coordinates and endpoint tangent vector of the first design profile and the starting coordinates and starting tangent vector of the second design profile, the third design profile of the middle section 20 of the short blade 100 is constructed using Hermite curves.
[0044] It is important to note that the Hermite curve is the contour line of the middle section 20 of the short blade 100. The end point of the contour line of the inlet section 10 of the short blade 100 is the starting point of the Hermite curve, and the starting point of the contour line of the outlet section 30 of the short blade 100 is the ending point of the Hermite curve. Constructing the middle section 20 of the short blade 100 using the Hermite curve ensures that the overall contour of the short blade 100 maintains coordinate continuity (positional continuity) and tangential vector continuity at the connection between the inlet section 10 and the middle section 20, achieving a smooth transition connection; and maintains coordinate continuity and tangential vector continuity at the connection between the middle section 20 and the outlet section 30, achieving a smooth transition connection. This ensures that the short blade 100 as a whole has a continuous, smooth, and curvature-controllable geometric contour, thereby improving the fluid rotation angle and velocity field distribution within the flow channel and enhancing the flow stability of the blade channel.
[0045] According to some embodiments of the present invention, determining a first design profile of the inlet section 10 of the short blade 100 and a second design profile of the outlet section 30 of the short blade 100, and constructing a third design profile of the intermediate section 20 of the short blade 100 based on the first and second design profiles using Hermite curves, includes: determining a first suction surface profile and a first pressure surface profile of the inlet section 10 of the short blade 100, the first suction surface profile and the first pressure surface profile constituting the first design profile; determining a second suction surface profile and a second pressure surface profile of the outlet section 30 of the short blade 100, the second suction surface profile and the second pressure surface profile constituting the second design profile; constructing a third suction surface profile of the intermediate section 20 of the short blade 100 based on the first suction surface profile and the second suction surface profile using Hermite curves; constructing a third pressure surface profile of the intermediate section 20 of the short blade 100 based on the first pressure surface profile and the second pressure surface profile using Hermite curves; the third suction surface profile and the third pressure surface profile constitute the third design profile. In this embodiment, the suction surface 101 and the pressure surface 102 are designed independently to obtain the complete design outline of the short blade 100.
[0046] According to some embodiments of the present invention, the Hermite curve formula for the middle section 20 of the short blade 100 is as follows:
[0047] In the formula, H PS ( t ( r The third pressure surface profile of the short blade 100 is represented by a cubic Hermite form. H SS ( t ( r)) is the cubic Hermite form of the third suction surface profile of the short blade 100; specifically, H PS ( t ( r )) H SS ( t ( r The calculation formula for )) is as follows:
[0048] In the formula, h 0( t ), h 1( t ), h 2( t ), h 3( t Let be a cubic Hermite basis function. The formula for a cubic Hermite basis function is:
[0049] C P0 ( r a () represents the starting coordinates of the third pressure surface profile; R ( i ) C P0 ( r b () represents the coordinates of the endpoint of the third pressure surface profile; C S0 ( r a () represents the starting coordinates of the third suction surface profile; R ( i ) C S0 ( r b () represents the coordinates of the endpoint of the third suction surface profile; M P0 ( r a () is an approximation of the starting tangent vector of the third pressure surface profile; R ( i ) M P0 ( r b ) is an approximation of the endpoint tangent vector of the third pressure surface profile; M S0 ( r aThe tangent vector of the starting point of the third suction surface profile is approximated. R ( i ) M S0 ( r b ) is an approximation of the endpoint tangent vector of the third suction surface profile; where,
[0050]
[0051]
[0052]
[0053] In the formula, d 11 , d 21 , d 12 , d 22 Each increment represents a small parameter increment along the direction of the corresponding contour curve parameter, used for a first-order difference approximation of the tangential direction of the contour curve at the start or end point. In the specific implementation, the parameter increment corresponds to the adjacent step size between discrete sampling points of the contour line, and its positive or negative direction is determined by the calculation position of the tangent vector. When the contour line is represented by a series of discrete coordinate points, the above difference operation is equivalent to the vector difference between adjacent coordinate points.
[0054] The design method for long and short split-flow impellers based on S-shaped short blades also includes the following steps: S3. Based on the first design profile, the second design profile, and the third design profile, generate the complete design profile of the short blade 100.
[0055] Since the two endpoints of the Hermite curve coincide with the contour endpoints of the inlet section 10 and the outlet section 30 of the short blade 100 respectively and have continuous tangent vectors, the Hermite curve obtained through the above steps can be smoothly connected with the design contour lines of the inlet section 10 and the outlet section 30 of the short blade 100, and the complete design contour of the short blade 100 is obtained after the connection.
[0056] Secondly, the present invention proposes a water pump, including an impeller, which is obtained by adopting the above-mentioned design method of long and short split-flow blade impeller based on S-shaped short blades.
[0057] like Figure 2 , 3 As shown, Figure 2The outline of the short blade 100 is obtained by the design method of long and short split impeller based on S-shaped short blades. The short blade 100 includes an inlet section 10, a middle section 20 and an outlet section 30. The outlet section 30 is rotated slightly relative to the original outlet section. The shape of the middle section 20 is determined by a cubic Hermite basis function. One end of the middle section 20 is smoothly connected to the inlet section 10, and the other end of the middle section 20 is smoothly connected to the outlet section 30.
[0058] Figure 1 The present invention relates to a long-short flow splitting impeller design method based on S-shaped short blades. The impeller comprises a hub 300 and multiple long blades 200 and multiple S-shaped short blades 100 disposed on the hub 300. The long blades 200 and short blades 100 are arranged alternately along the circumference in a repeating pattern of "long blade-short blade-long blade" on the hub 300. The long-short flow splitting impeller proposed in this invention, and the water pump based on it, can effectively weaken the unfavorable vortex structure within the blade channel and improve the overall efficiency of the water pump.
[0059] This invention, through the combination of the inlet section 10, the intermediate section 20, and the outlet section 30, designs the overall profile of the short blade 100 as S-shaped, possessing continuous, smooth, and controllable curvature geometry throughout the design range. This improves the fluid rotation angle and velocity field distribution within the flow channel, enhancing the flow stability of the blade channel. The S-shaped profile effectively mitigates the pressure gradient near the pressure surface 102 and suction surface 101 of the short blade 100, reducing secondary flow and local separation tendencies. Consequently, it enhances the overall hydraulic performance and efficiency of the pump, achieving effective control over fluid flow. Therefore, this invention solves the problems of large local pressure gradients in existing short blade channels, which easily induce unfavorable flow phenomena such as wake vortices, thus affecting overall energy transfer efficiency, and the difficulty of effectively controlling flow while ensuring stable outlet flow direction in existing short blades.
[0060] 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 are not intended to 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.
[0061] In the description of this invention, "first feature" and "second feature" may include one or more of the features.
[0062] In the description of this invention, "a plurality of" means two or more.
[0063] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.
[0064] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.
[0065] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0066] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims
1. A design method for long and short split-flow impellers based on S-shaped short blades, characterized in that, The long and short split-blade impeller includes a hub, several long blades, and several short blades. Both the long and short blades include a pressure surface and a suction surface. The short blades are S-shaped and comprise an inlet section, a middle section, and an outlet section. The shape of the middle section is determined by a cubic Hermite basis function. One end of the middle section smoothly transitions to the inlet section, and the other end smoothly transitions to the outlet section. The design outline of the short blades is also described. C ( r The expression for ) is: In the formula, C 0( r () represents the original outline. H ( t ( r )) represents the Hermite curve. R ( θ ) is a rotation matrix. r a This refers to the starting radial position of the intermediate segment. r b This refers to the starting radial position of the outlet section. r c The radial position of the end point of the aforementioned outlet section. t ( r () is a radial parameter mapping function used to map physical radial coordinates. r Normalize to the dimensionless interval [0,1]. t ( r The formula for ) is: 。 2. The design method for long and short split-flow blade impellers based on S-shaped short blades according to claim 1, characterized in that, The method for designing long and short split-flow impellers based on S-shaped short blades includes the following steps: Determine the first design profile of the short blade inlet section and the second design profile of the short blade outlet section; Based on the first design profile and the second design profile, a third design profile for the middle section of the short blade is constructed using Hermite curves. Based on the first design profile, the second design profile, and the third design profile, the complete design profile of the short blade is generated.
3. The method for designing long and short split-flow impellers based on S-shaped short blades according to claim 2, characterized in that, Determining the first design profile and the second design profile includes: Obtain the original profile of the short blade, the original profile including a first original profile of the inlet section and a second original profile of the outlet section; The first original contour is used as the first design contour; Rotate the second original profile about the axis of the impeller by an angle θ Then, the second design profile is obtained.
4. The design method for long and short split-flow impellers based on S-shaped short blades according to claim 3, characterized in that, Obtaining the original profile of the short blade includes: The outline features of the long blade are obtained, including blade shape features and leading edge features. The blade shape features include the distribution of the mid-curve, the thickness distribution, and the variation law of the installation angle. The leading edge features include the leading edge rounding radius and the leading edge rounding form. The long blade was selected at 0.
8. R~R The leaf shape features within the radial interval are used as the original profile leaf shape features of the short blade; wherein, R The impeller outlet radius; The leading edge feature of the long blade is selected as the original outline leading edge feature of the short blade; The original outline of the short blade is generated based on the original profile leaf shape features and the original profile leading edge features of the short blade.
5. The design method for long and short split-flow impellers based on S-shaped short blades according to claim 2, characterized in that, The process of determining a first design profile for the inlet section of the short blade and a second design profile for the outlet section of the short blade, and then constructing a third design profile for the middle section of the short blade using Hermite curves based on the first and second design profiles, includes: The first suction surface profile and the first pressure surface profile of the short blade inlet section are determined, and the first suction surface profile and the first pressure surface profile constitute the first design profile. The second suction surface profile and the second pressure surface profile of the short blade outlet section are determined, and the second suction surface profile and the second pressure surface profile constitute the second design profile. Based on the first suction surface profile and the second suction surface profile, a third suction surface profile of the middle section of the short blade is constructed using Hermite curves; based on the first pressure surface profile and the second pressure surface profile, a third pressure surface profile of the middle section of the short blade is constructed using Hermite curves; the third suction surface profile and the third pressure surface profile constitute the third design profile.
6. The method for designing long and short split-flow impellers based on S-shaped short blades according to claim 1, characterized in that, The rotation matrix R ( θ The formula for ) is: 。 7. The method for designing long and short split-flow impellers based on S-shaped short blades according to claim 5, characterized in that, The formula for the Hermite curve is: In the formula, H PS ( t ( r ))and H SS ( t ( r The three ')'s are the cubic Hermite forms of the third pressure surface profile and the third suction surface profile of the short blade, respectively, and the specific formulas are as follows: In the formula, h 0( t ), h 1( t ), h 2( t ), h 3( t ) are cubic Hermite basis functions; C P0 ( r a () represents the starting coordinates of the third pressure surface profile of the short blade; R ( θ ) C P0 ( r b () represents the endpoint coordinates of the third pressure surface profile of the short blade; C S0 ( r a () represents the starting coordinates of the profile of the third suction surface of the short blade; R ( θ ) C S0 ( r b ) represents the endpoint coordinates of the profile of the third suction surface of the short blade; M P0 ( r a () is an approximation of the starting tangent vector of the profile of the third pressure surface of the short blade; R ( θ ) M P0 ( r b The endpoint tangent vector of the third pressure surface profile of the short blade is approximated. M S0 ( r a ) is an approximation of the starting tangent vector of the profile of the third suction surface of the short blade; R ( θ ) M S0 ( r b ) is an approximation of the endpoint tangent vector of the profile of the third suction surface of the short blade.
8. The method for designing long and short split-flow impellers based on S-shaped short blades according to claim 7, characterized in that, The formula for the cubic Hermite basis functions is: 。 9. The method for designing long and short split-flow impellers based on S-shaped short blades according to claim 7, characterized in that, The approximate calculation formula for the starting tangent vector of the third pressure surface profile of the short blade is as follows: The approximate formula for calculating the endpoint tangent vector of the third pressure surface profile of the short blade is as follows: The approximate calculation formula for the starting tangent vector of the third suction surface profile of the short blade is as follows: The approximate calculation formula for the endpoint tangent vector of the third suction surface profile of the short blade is as follows: In the formula, δ 11 , δ 21 , δ 12 , δ 22 Each represents a small parameter increment along the direction of the corresponding contour curve parameter, used to perform a first-order difference approximation of the tangential direction of the contour curve at the start or end point; the parameter increment corresponds to the adjacent step size between discrete sampling points of the contour line, and its positive or negative direction is determined by the calculation position of the tangential vector; when the contour line is represented by a series of discrete coordinate points, the above difference operation is equivalent to the vector difference between adjacent coordinate points.
10. A water pump, characterized in that, The impeller is obtained by the long and short split-flow blade impeller design method based on S-shaped short blades as described in any one of claims 1-9.