Design method for inter-stage flow channel of guide vane type multi-stage centrifugal pump and centrifugal pump

Abstract

The invention provides a guide vane type multi-stage centrifugal pump interstage flow channel design method and a centrifugal pump. The method comprises the steps that a first arc of an impeller front cover plate streamline is obtained, and a first tangent point and a second tangent point of the first arc are obtained; calculating a first width according to the suction inlet diameter of the impeller suction inlet, the hub diameter and the radius of the first arc, and calculating a second width according to the suction inlet diameter of the impeller suction inlet and the hub diameter; a horizontal axial flow surface is obtained, and a second arc tangent to the guide vane cover plate and the horizontal axial flow surface is made; a first inscribed circle tangent to the first arc and the second arc is made with the first width as the diameter, a second inscribed circle tangent to the first arc and the horizontal axial flow face is made with the second width as the diameter, and a plurality of inscribed circles tangent to the first arc and the second arc are made between the first inscribed circle and the second inscribed circle; a cross-sectional circle area corresponding to the first inscribed circle, the plurality of inscribed circles, and the second inscribed circle is calculated. According to the invention, the flow surface of the interstage flow channel can be more balanced.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal pumps, and in particular to a method for designing an interstage flow passage of a guide vane multi-stage centrifugal pump and a centrifugal pump. Background Art

[0002] Guide vane multistage centrifugal pumps are widely used due to their reliable structure, wide head range, and wide range of applicable operating conditions. Guide vane multistage centrifugal pumps have various components, among which the interstage flow passage is a crucial component for ensuring excellent hydraulic and mechanical performance. The interstage flow passage is the section where the fluid flows from the impeller and guide vanes to the inlet of the next-stage impeller.

[0003] The number of interstage flow passages increases with the number of pump stages. This large number significantly impacts pump performance. Existing interstage flow passages are designed based on experience, and there is no definitive design methodology. Improper interstage flow passage design can lead to oversizing, undersizing, or sudden changes, reducing pump efficiency. Backflow can also excite the rotor, causing low-frequency vibrations during operation. Summary of the Invention

[0004] In order to overcome the defects in the prior art, an embodiment of the present invention provides a guide vane multi-stage centrifugal pump interstage flow channel design method and a centrifugal pump, which can make the flow surface of the interstage flow channel more balanced, ensure that the liquid flow in the interstage flow channel is more stable, and avoid the reduction of pump efficiency due to uneven flow surface of the interstage flow channel.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: The first aspect of the present invention discloses a method for designing an interstage flow passage of a guide vane multi-stage centrifugal pump, comprising: Obtain a first circular arc of the impeller front cover streamline, and obtain a first tangent point and a second tangent point of the first circular arc; Calculating a first width based on the suction port diameter of the impeller suction port, the hub diameter, and the radius of the first arc, and calculating a second width based on the suction port diameter of the impeller suction port and the hub diameter; Obtain a horizontal axial flow surface, and draw a second arc tangent to the guide vane shroud and the horizontal axial flow surface, respectively. The distance between the tangent point of the second arc with the guide vane shroud and the first tangent point is the first width, and the distance between the tangent point of the second arc with the horizontal axial flow surface and the second tangent point is the second width. A first inscribed circle is made with the first width as the diameter and is tangent to the first arc and the second arc respectively. A second inscribed circle is made with the second width as the diameter and is tangent to the first arc and the horizontal axial flow surface respectively. Multiple inscribed circles are made between the first inscribed circle and the second inscribed circle and are tangent to the first arc and the second arc. The areas of the cross-sectional circles corresponding to the first inscribed circle, the multiple inscribed circles, and the second inscribed circle are calculated. The curvature of the second arc is adjusted according to the area difference of the multiple cross-sectional circles until the area difference decreases linearly.

[0006] The above technical solution calculates the width of the two ends of the interstage flow channel to be designed through the suction port diameter of the impeller suction port, the hub diameter and the radius of the first arc, and presets the interstage flow channel according to the width of the two ends of the interstage flow channel to be designed, that is, the second arc, and then adjusts the curvature of the interstage flow channel according to the area change of the cross-sectional circle corresponding to the inscribed circle in the preset interstage flow channel. The interstage flow channel after adjusting the curvature is the target interstage flow channel to be designed. The flow surface of the interstage flow channel obtained by the above solution is more balanced, and the liquid flow in the interstage flow channel can obtain a balanced velocity field, thereby ensuring that the liquid flow in the interstage flow channel is more stable, and avoiding the reduction of pump efficiency due to uneven interstage flow channel.

[0007] Furthermore, let the area of the nth cross-sectional circle be S n , n≥1, where S1 is the area of the cross-section circle corresponding to the first inscribed circle, If S n+1 ≥S n , then move the second arc that is tangent to the n+1th inscribed circle toward the direction close to the first arc; If S n+1 <S n , and Δ n >Δ n+1 , then move the second arc that is tangent to the n+1th inscribed circle toward the direction close to the first arc; If S n+1 <S n , and Δ n <Δ n+1 , then the second arc tangent to the n+1th inscribed circle is moved in the direction away from the first arc, where Δ n =S n -S n+1 .

[0008] Furthermore, the second arc is formed by connecting at least two arc segments, and the area differences of the cross-sectional circles corresponding to the multiple inscribed circles within the at least two arc segments all decrease linearly. If the second arc cannot be formed as a continuous and complete arc so that the multiple inscribed circles all decrease linearly, the second arc may be formed by connecting two or more arc segments.

[0009] Furthermore, the horizontal axial flow surface is formed by a horizontal tangent of the impeller rear cover streamline rotating around the center line of the shaft.

[0010] Furthermore, it also includes: Draw a horizontal reference line and a vertical reference line, wherein the extension lines of the horizontal reference line and the vertical reference line both pass through the center of the first arc, the first tangent point is located on the horizontal reference line, and the second tangent point is located on the vertical reference line; The first width is the width of the horizontal reference line, the second width is the width of the vertical reference line, and the area variation range of the cross-sectional circles corresponding to the multiple inscribed circles is within the area from the horizontal reference line to the vertical reference line.

[0011] Furthermore, the first width is calculated as follows: ; Among them, d j is the diameter of the impeller suction port, d z is the hub diameter of the impeller, R s is the radius of the first arc.

[0012] Furthermore, the second width is 0.5 times the difference between the suction port diameter of the impeller suction port and the hub diameter.

[0013] Furthermore, it also includes: Get the tangent points of the inscribed circle, the first arc and the second arc respectively; A perpendicular line is drawn through the center of the inscribed circle to connect the two tangent points, and the perpendicular line and the connecting line have an intersection point; Divide the perpendicular line into three equal parts, and obtain equal division points between the intersection point and the center point of the inscribed circle; Obtain the radius of the equally divided point close to the intersection point and the line connecting the center of the circle and the tangent point of the inscribed circle and the first arc; Calculate the cross-sectional area of the inscribed circle.

[0014] Furthermore, the area of the cross-sectional circle corresponding to the inscribed circle is calculated as follows: ; Where AB is the length of the line connecting the two tangent points, OB is the length of the line connecting the center of the circle and the tangent point of the inscribed circle and the first arc, and Re is the distance from the equal-division point near the intersection point to the centerline of the shaft.

[0015] A second aspect of the present invention discloses a centrifugal pump, comprising an interstage flow passage designed by the design method described in any one of the first aspects.

[0016] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: The present application calculates the width of the two ends of the interstage flow channel to be designed through the suction port diameter of the impeller suction port, the hub diameter and the radius of the first arc, presets the interstage flow channel according to the width of the two ends of the interstage flow channel to be designed, that is, the second arc, and then adjusts the curvature of the interstage flow channel according to the area change of the cross-sectional circle corresponding to the inscribed circle in the preset interstage flow channel. The interstage flow channel after adjusting the curvature is the target interstage flow channel to be designed. The flow surface of the interstage flow channel obtained by the above scheme is more balanced, and the liquid flow in the interstage flow channel can obtain a balanced velocity field, thereby ensuring that the liquid flow in the interstage flow channel is more stable, and avoiding the reduction of pump efficiency due to uneven interstage flow channel.

[0017] In order to make the above and other objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic structural diagram of an interstage flow passage between a guide vane multistage centrifugal pump provided by one embodiment of the present invention; Figure 2 A diagram for calculating the cross-sectional circular area of an interstage flow passage provided in one embodiment of the present invention; Figure 3 This is a structural diagram of an interstage flow passage provided by one embodiment of the present invention; Figure 4 This is a cross-sectional view of an interstage flow passage provided by one embodiment of the present invention.

[0020] The figure marks in the above drawings are: 1. shaft; 2. upper impeller; 3. lower impeller; 4. impeller retaining ring; 5. guide vane sleeve; 6. guide vane; 601, guide vane cover; 7. middle section module; 8. impeller front cover; 9. impeller rear cover; 10. first arc; 11. second arc; 12. interstage flow channel to be designed. DETAILED DESCRIPTION

[0021] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. In addition, the drawings of the present invention are only for simple schematic illustration and are not depicted to actual size. Please note in advance.

[0022] In the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", "forward", "back", "between", "close to", "far away" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention. It should also be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0023] It should be understood that although terms such as "first," "second," and "third" may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another, or one signal from another. In addition, the term "or" as used herein may include any one or more combinations of the associated listed items, as appropriate.

[0024] Reference Figures 1 to 4 , an embodiment of the present application provides an inter-stage flow channel structure of a guide vane multi-stage centrifugal pump.

[0025] The guide vane multistage centrifugal pump comprises a housing and a core package assembly arranged in the housing. The housing has a suction port and a discharge port, and the core package assembly is connected to the suction port and the discharge port.

[0026] The core package assembly includes a shaft 1 and multiple impeller modules sleeved on the shaft 1. In the centrifugal pump interstage flow channel structure provided in the embodiment of the present application, the impeller modules are heat-fitted onto the shaft 1, and the shaft diameter of the shaft 1 is larger than the hub diameter of the impeller suction port. At the same time, to facilitate the disassembly and assembly of the impeller modules, the shaft diameter of the impeller is gradually reduced by 0.1mm, and accordingly, the size of the shaft 1 is also gradually reduced by 0.1mm. In other possible embodiments, the impeller modules are slidably mounted on the shaft 1, which is not specifically limited in this application.

[0027] It should be noted that the embodiments of this application are Figure 1 Only the partial structural diagram of the upper half of the center line of the centrifugal pump shaft 1 is shown.

[0028] Each impeller module includes an impeller and a guide vane 6 connected to the impeller. The guide vane 6 is arranged on the discharge side of the impeller and includes a guide vane cover 601. In addition, a guide vane sleeve 5 is installed on the guide vane 6.

[0029] The impeller is axially positioned on the shaft 1 by an impeller retaining ring 4 provided on the shaft 1. The impeller retaining ring 4 has a circular cross-section, and the retaining ring groove on the shaft 1 for mounting the impeller retaining ring 4 has an arc-shaped cross-section that matches the cross-section of the impeller retaining ring 4. A mid-section module 7 is also provided between each impeller module.

[0030] The interstage flow passage to be designed in the embodiment of the present application is arranged between two adjacent impeller modules. Figure 3 As shown in FIG, from the axial direction of shaft 1, the interstage flow channel to be designed is annular, and the surface in contact with the fluid is an arc surface, as shown in FIG. Figure 4 As shown, viewed from the radial direction of the shaft 1 , the cross section of the interstage flow passage to be designed that contacts the fluid is in the shape of an arc.

[0031] For ease of distinction, the impellers of two adjacent impeller modules are referred to as the upper-stage impeller 2 and the lower-stage impeller 3, respectively. The lower-stage impeller 3 is located in front of the upper-stage impeller 2, with the reference direction of the front side being the medium flow direction. That is, the medium flows from the upper-stage impeller 2 to the lower-stage impeller 3. Similarly, the upper-stage impeller 2 is located behind the lower-stage impeller 3, with the reference direction of the rear side being the medium flow direction. In this embodiment, the medium can be water, gasoline, or other materials, and this application does not impose specific limitations.

[0032] The interstage flow channel design method of the present application can make the arc surface of the designed interstage flow channel in contact with the fluid more balanced, and can increase the liquid flow velocity flowing through the interstage flow channel by 5% to 15%, thereby avoiding the problems of reduced pump efficiency caused by uneven liquid flow velocity in the interstage flow channel due to excessively large or too small cross-section of the interstage flow channel, sudden changes, etc., and low-frequency vibration of the rotor caused by excitation generated by eddy currents, and can ensure that the liquid flow in the interstage flow channel is more stable to obtain a balanced velocity field.

[0033] Specific, combined Figures 1 to 4 The present invention provides a method for designing an interstage flow passage of a guide vane multi-stage centrifugal pump, including: Step 1: Obtain a first arc 10 of the streamline of the front cover of the lower-stage impeller 3, and obtain a first tangent point and a second tangent point of the first arc 10.

[0034] Among them, the first arc 10 is the arc of the streamline of the impeller suction port front cover 8. The center and radius of the first arc 10 are known and have been determined when designing the impeller. The center and radius of the first arc 10 can be adjusted according to actual conditions.

[0035] Step 2: Calculate the first width W1 based on the suction port diameter of the lower stage impeller 3, the hub diameter and the radius of the first arc 10, and calculate the second width W2 based on the suction port diameter of the lower stage impeller 3 and the hub diameter.

[0036] Specifically, the first width W1 is calculated by substituting the suction port diameter of the suction port of the lower-stage impeller 3, the hub diameter, and the radius of the first arc 10 into the calculation formula: ; Among them, d z is the hub diameter of the impeller, d j is the diameter of the impeller suction port, R s is the radius of the first arc.

[0037] The second width W2 is calculated by subtracting the hub diameter from the suction port diameter of the lower-stage impeller 3 and dividing the difference by 2.

[0038] This step also includes determining the interval of the interstage flow passage to be designed, specifically including: Draw a horizontal reference line a and a vertical reference line b, and the extension lines of the horizontal reference line a and the vertical reference line b both pass through the center of the first arc 10, the first tangent point is located on the horizontal reference line a, and the second tangent point is located on the vertical reference line b; The first width W1 is the width of the horizontal reference line a, the second width W2 is the width of the vertical reference line b, and the interval between the horizontal reference line a and the vertical reference line b is the interstage flow channel interval to be designed.

[0039] The first tangent point of the first arc 10 is the intersection of the horizontal reference line a and the first arc 10 , and the second tangent point of the first arc 10 is the intersection of the vertical reference line b and the first arc 10 .

[0040] It should be noted that the diameter of the suction port of the lower-stage impeller 3 is the distance between the horizontal reference lines a on both sides of the shaft, the hub diameter of the impeller is the distance between the horizontal tangents of the streamlines of the impeller rear cover plate 9 of the lower-stage impeller 3, and the suction port diameter, hub diameter and radius of the first arc Rs of the suction port of the lower-stage impeller 3 are all known. The values of the above parameters have been determined when designing the impeller.

[0041] Step 3: Obtain the horizontal axial flow surface and make a second arc 11 that is tangent to the guide vane cover 601 and the horizontal axial flow surface respectively. The distance between the tangent point of the second arc 11 with the guide vane cover 601 and the first tangent point is the first width W1, and the distance between the tangent point of the second arc 11 with the horizontal axial flow surface and the second tangent point is the second width W2.

[0042] The horizontal tangent of the streamlines of the impeller shroud 9 of the lower-stage impeller 3 rotates around the centerline of the shaft 1 to form the horizontal axial flow surface. The second arc 11 lies between the horizontal reference line a and the vertical reference line b. It is worth noting that in this structure, the hydraulic components of the upper-stage impeller 2 and upper-stage guide vanes 6, and the lower-stage impeller 3 and lower-stage guide vanes 6, which form the interstage flow passage, are identical.

[0043] Through the above method, the embodiment of the present application can only obtain the width of the inlet (horizontal reference line a) and the outlet (vertical reference line b) of the interstage flow channel, but cannot obtain the width value of the interstage flow channel between the inlet and the outlet. The second arc 11 is an arc of arbitrary curvature made according to actual conditions after determining the endpoints at both ends of the interstage flow channel to be designed, that is, viewed from the radial direction of the axis 1, the second arc 11 is the cross-section of the preset interstage flow channel. By adjusting the curvature of the second arc 11, its curvature is made more balanced to ensure that the arc surface of the designed interstage flow channel in contact with the fluid is more balanced, thereby making the liquid flow through the interstage flow channel more stable.

[0044] Step 4: Use the first width W1 as the diameter to make a first inscribed circle that is tangent to the first arc 10 and the second arc 11 respectively, and use the second width W2 as the diameter to make a second inscribed circle that is tangent to the first arc 10 and the horizontal axial flow surface respectively. Make multiple inscribed circles that are tangent to the first arc 10 and the second arc 11 between the first inscribed circle and the second inscribed circle, calculate the cross-sectional circle areas corresponding to the first inscribed circle, the multiple inscribed circles, and the second inscribed circle, and adjust the curvature of the second arc 11 according to the area difference of the multiple cross-sectional circles until the area difference decreases linearly.

[0045] The interstage flow passage is annular, and the cross-sectional circle is: the cross-sectional area of the surface of the interstage flow passage to be designed in contact with the fluid, viewed from the axial direction of the shaft 1 , and the plurality is more than one.

[0046] Specifically, the area of the inscribed circle is calculated as follows: The tangent points of the inscribed circle with the first arc and the second arc are obtained respectively. In this embodiment, the tangent points of the second arc and the inscribed circle are marked with A and B respectively.

[0047] There is a perpendicular line (OP) between the line (AB) connecting the two tangent points and the center (O) of the inscribed circle, and the perpendicular line (OP) and the line (AB) have an intersection point (P); Divide the perpendicular line (OP) into three equal parts to obtain equal points (P1, P2) between the intersection point (P) and the center point (O) of the inscribed circle; Get the radius of the bisection point (P1) close to the intersection point; Calculate the area of the cross-section circle corresponding to the inscribed circle, specifically: ; Where AB is the length of the line connecting the two tangent points, OB is the length of the line connecting the center of the circle and the tangent point of the inscribed circle and the first arc, and Re is the distance from the equal-division point near the intersection point to the centerline of the shaft.

[0048] The cross-sectional circle areas corresponding to the first inscribed circle and the second inscribed circle can be calculated according to an existing formula for calculating circle area, and the cross-sectional circle area corresponding to the first inscribed circle is greater than the cross-sectional circle area corresponding to the second inscribed circle.

[0049] The specific method of adjusting the second arc 11 is: Let the area of the nth cross-sectional circle be S n , n≥1, where S1 is the area of the cross-section circle corresponding to the first inscribed circle, S n is the area of the cross-section circle corresponding to the nth inscribed circle, If S n+1 ≥S n , then move the second arc that is tangent to the n+1th inscribed circle toward the direction close to the first arc; If S n+1 <S n , and Δ n >Δ n+1 , then move the second arc that is tangent to the n+1th inscribed circle toward the direction close to the first arc; If S n+1 <S n , and Δ n <Δ n+1 , then the second arc tangent to the n+1th inscribed circle is moved in the direction away from the first arc, where Δ n =S n -S n+1 .

[0050] If the adjusted second arc still cannot satisfy the requirement that the area differences of the cross-sectional circles corresponding to all inscribed circles are linearly decreasing, the second arc is split into at least two connected arcs, and the area differences of the cross-sectional circles corresponding to multiple inscribed circles in at least two connected arcs are linearly decreasing.

[0051] An embodiment of the present application further provides a centrifugal pump, which includes an interstage flow channel designed by the design method described in the above embodiment.

[0052] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A method for designing interstage flow passages of a guide vane multistage centrifugal pump, characterized in that: include: Obtain a first circular arc of the impeller front cover streamline, and obtain a first tangent point and a second tangent point of the first circular arc; Calculating a first width based on the suction port diameter of the impeller suction port, the hub diameter, and the radius of the first arc, and calculating a second width based on the suction port diameter of the impeller suction port and the hub diameter; Obtain a horizontal axial flow surface, and draw a second arc tangent to the guide vane shroud and the horizontal axial flow surface, respectively. The distance between the tangent point of the second arc with the guide vane shroud and the first tangent point is the first width, and the distance between the tangent point of the second arc with the horizontal axial flow surface and the second tangent point is the second width. A first inscribed circle is made with the first width as the diameter and is tangent to the first arc and the second arc respectively. A second inscribed circle is made with the second width as the diameter and is tangent to the first arc and the horizontal axial flow surface respectively. Multiple inscribed circles are made between the first inscribed circle and the second inscribed circle and are tangent to the first arc and the second arc. The areas of the cross-sectional circles corresponding to the first inscribed circle, the multiple inscribed circles, and the second inscribed circle are calculated. The curvature of the second arc is adjusted according to the area difference of the multiple cross-sectional circles until the area difference decreases linearly.

2. The method for designing interstage flow passages of a guide vane multistage centrifugal pump according to claim 1, characterized in that: Let the area of the nth cross-sectional circle be S n , n≥1, where S1 is the area of the cross-section circle corresponding to the first inscribed circle, If S n+1 ≥S n , then move the second arc that is tangent to the n+1th inscribed circle toward the direction close to the first arc; If S n+1 <S n , and Δ n >Δ n+1 , then move the second arc that is tangent to the n+1th inscribed circle toward the direction close to the first arc; If S n+1 <S n , and Δ n <Δ n+1 , then the second arc tangent to the n+1th inscribed circle is moved in the direction away from the first arc, where Δ n =S n -S n+1 .

3. The method for designing interstage flow passages of a guide vane multistage centrifugal pump according to claim 1, characterized in that: The second circular arc is formed by connecting at least two circular arcs, and the area differences of the cross-sectional circles corresponding to the multiple inscribed circles in the at least two circular arcs are all linearly decreasing.

4. The method for designing interstage flow passages of a guide vane multistage centrifugal pump according to claim 1, characterized in that: The horizontal axial flow surface is formed by the horizontal tangent of the impeller rear cover streamline rotating around the center line of the shaft.

5. The method for designing interstage flow passages of a guide vane multistage centrifugal pump according to claim 1, characterized in that: Also includes: Draw a horizontal reference line and a vertical reference line, wherein the extension lines of the horizontal reference line and the vertical reference line both pass through the center of the first arc, the first tangent point is located on the horizontal reference line, and the second tangent point is located on the vertical reference line; The first width is the width of the horizontal reference line, the second width is the width of the vertical reference line, and the area variation range of the cross-sectional circles corresponding to the multiple inscribed circles is within the area from the horizontal reference line to the vertical reference line.

6. The method for designing interstage flow passages of a guide vane multistage centrifugal pump according to claim 1, characterized in that: The first width is calculated as follows: ； Among them, d j is the diameter of the impeller suction port, d z is the hub diameter of the impeller, R s is the radius of the first arc.

7. The method for designing interstage flow passages of a guide vane multistage centrifugal pump according to claim 1, characterized in that: The second width is 0.5 times the difference between the suction port diameter of the impeller suction port and the hub diameter.

8. The method for designing interstage flow passages of a guide vane multistage centrifugal pump according to claim 1, characterized in that: Also includes: Get the tangent points of the inscribed circle, the first arc and the second arc respectively; A perpendicular line is drawn through the center of the inscribed circle to connect the two tangent points, and the perpendicular line and the connecting line have an intersection point; Divide the perpendicular line into three equal parts, and obtain equal division points between the intersection point and the center point of the inscribed circle; Obtain the radius of the equally divided point close to the intersection point and the line connecting the center of the circle and the tangent point of the inscribed circle and the first arc; Calculate the cross-sectional area of the inscribed circle.

9. The method for designing interstage flow passages of a guide vane multistage centrifugal pump according to claim 8, characterized in that: The area of the cross-section circle corresponding to the inscribed circle is calculated as follows: ； Where AB is the length of the line connecting the two tangent points, OB is the length of the line connecting the center of the circle and the tangent point of the inscribed circle and the first arc, and Re is the distance from the equal-division point near the intersection point to the centerline of the shaft.

10. A centrifugal pump, characterized in that: The centrifugal pump includes an interstage flow channel designed by the design method according to any one of claims 1 to 9.

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