CN115013318A - Double-suction impeller structure for multistage centrifugal pump and design method thereof - Google Patents

Double-suction impeller structure for multistage centrifugal pump and design method thereof Download PDF

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CN115013318A
CN115013318A CN202210732020.2A CN202210732020A CN115013318A CN 115013318 A CN115013318 A CN 115013318A CN 202210732020 A CN202210732020 A CN 202210732020A CN 115013318 A CN115013318 A CN 115013318A
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impeller
double
suction
outlet
opening ring
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李晓俊
林言丕
朱祖超
李良
其他发明人请求不公开姓名
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Zhejiang Sci Tech University ZSTU
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D1/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
    • F04D1/006—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps double suction pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D1/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
    • F04D1/06—Multi-stage pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/18—Rotors
    • F04D29/22—Rotors specially for centrifugal pumps
    • F04D29/2261—Rotors specially for centrifugal pumps with special measures
    • F04D29/2272—Rotors specially for centrifugal pumps with special measures for influencing flow or boundary layer
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
    • F04D29/666—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps by means of rotor construction or layout, e.g. unequal distribution of blades or vanes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
    • F04D29/667—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps by influencing the flow pattern, e.g. suppression of turbulence
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/17—Mechanical parametric or variational design
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces

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Abstract

The invention discloses a double-suction impeller structure for a multistage centrifugal pump, which comprises a first blade, a first cover plate, a first outlet, a first opening ring, a first impeller flow passage, a second blade, a second cover plate, a second outlet, a second opening ring, a second impeller flow passage and a hub, wherein the two axial ends of the first outlet and the two axial ends of the second outlet are respectively flush and have the same axial width, and the first outlet and the second outlet are alternately arranged/spaced in the circumferential direction, and the double-suction impeller structure is characterized in that: the first opening ring (13) is provided with a first opening ring outer edge (131) and a first opening ring inner edge (132), the first opening ring outer edge is circular, the first opening ring inner edge is in a first ellipse shape, the second opening ring (23) is provided with a second opening ring outer edge and a second opening ring inner edge (232), the second opening ring outer edge is circular, the second opening ring inner edge is in a second ellipse shape, and the long axis of the first ellipse shape is perpendicular to the long axis of the second ellipse shape. The invention can effectively improve the anti-cavitation performance of the centrifugal pump.

Description

Double-suction impeller structure for multistage centrifugal pump and design method thereof
Technical Field
The invention relates to the technical field of multistage centrifugal pumps, in particular to a double-suction impeller structure for a multistage centrifugal pump and a design method thereof.
Background
As shown in fig. 1, the prior art JP2018-105298A discloses a high-efficiency double-suction impeller structure, wherein the outlet end of a first impeller flow passage has a first outlet, the outlet end of a second impeller flow passage has a second outlet, the axial two ends of the first outlet and the axial two ends of the second outlet are respectively flush and have the same axial width, and the first outlet and the second outlet are alternately arranged/spaced in the circumferential direction, so that the axial size of the double-suction impeller can be reduced. However, the conventional double-suction impeller structure reduces the axial size of the double-suction impeller, and simultaneously reduces the corresponding cavitation resistance.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a double-suction impeller structure for a multistage centrifugal pump and a design method thereof. By the design method, the cavitation resistance of the centrifugal pump can be improved, so that the overall efficiency of the centrifugal pump is improved.
In order to achieve the purpose, the invention adopts the technical scheme that:
a double-suction impeller structure for a multistage centrifugal pump comprises first blades (10), a first cover plate (11), a first outlet (12), a first opening ring (13), a first impeller flow passage (P1), second blades (20), a second cover plate (21), a second outlet (22), a second opening ring (23), a second impeller flow passage (P2) and a hub (30), wherein the hub comprises a first hub part (31) and a second hub part (32) which are symmetrically arranged, the first blades and the second blades are symmetrically arranged, the first impeller flow passage (P1) is formed between every two adjacent first blades, the second impeller flow passage (P2) is formed between every two adjacent second blades (20), the outlet end of the first impeller flow passage is provided with the first outlet, the outlet end of the second impeller flow passage is provided with the second outlet, the axial two ends of the first outlet are respectively flush with the axial two ends of the second outlet and have the same axial width, in the circumference, first export and second export are arranged alternately/interval, and the end of first apron has first choma, and the end of second apron has second choma, its characterized in that: the first opening ring (13) is provided with a first opening ring outer edge (131) and a first opening ring inner edge (132), the first opening ring outer edge is circular, the first opening ring inner edge is first oval, the second opening ring (23) is provided with a second opening ring outer edge and a second opening ring inner edge (232), the second opening ring outer edge is circular, the second opening ring inner edge is second oval, and the long axis (2a) of the first oval is perpendicular to the long axis of the second oval.
Further, the hub (30) has a hub axial end outer edge (33) at its axial end, the hub axial end outer edge having a radius R, the first ellipse and/or the second ellipse having a major axis a, a minor axis b, (1.05-1.2) b, and R, (0.5-0.65) a.
Furthermore, a plurality of grooves (331) are arranged on the outer peripheral surface of the outer edge (33) of the axial end part of the hub, and are distributed along the circumferential direction.
Further, the radial depth of the groove (331) is 0.25 to 0.4 times the radial thickness of the first hub portion (31), and the axial depth of the groove (331) is 0.5 to 2 times the radial thickness of the first hub portion (31).
Furthermore, the first cover plate (11) is provided with a first cover plate inner side wall (111), concave-convex parts (112) are arranged on the surface of the first cover plate inner side wall and positioned in the first impeller flow passage (P1), the concave-convex parts are wavy, and the concave-convex parts extend from the downstream of the first opening ring (13) to the first outlet (12).
Further, in the circumferential direction, the concave-convex portion (112) is provided only in a region corresponding to the minor axis of the first ellipse, the region being 60 to 150 ° in the circumferential direction.
Further, the second cover plate (21) is provided with a second cover plate inner side wall, a second concave-convex part is arranged on the surface of the second cover plate inner side wall and positioned in the second impeller channel (P2), the second concave-convex part is wavy, and the second concave-convex part extends from the downstream of the second opening ring to the second outlet; in the circumferential direction, the second concave-convex part is only arranged in a region corresponding to the short axis of the second ellipse, the region is 60-150 degrees in the circumferential direction, and the structure has the same concave-convex part structure with the inner side wall of the first cover plate.
A design method of a double-suction impeller structure for a multistage centrifugal pump is characterized by comprising the following steps:
during design/calculation, each parameter/each variable is measured, and the numerical part is designed/calculated;
1) determining the specific speed n of the double suction impeller q Calculated in the following way:
Figure BDA0003714152870000021
in the formula: f. of q -impeller suction port number; q BEP -rated flow of the multistage pump; n-rated rotation speed; h BEP -designing a lift;
2) determining a flow channel central line r of an impeller flow channel; the central line of the flow channel is a variable Archimedes spiral line and is calculated according to the following equation:
Figure BDA0003714152870000031
in the formula: r-original flow channel centerline; d 2 Outlet of flow channelThe diameter of the mouth; theta-polar angle;
Figure BDA0003714152870000032
-flow channel centerline wrap angle;
3) determining the width b of the outlet and the inclination angle T of the cover plate of the suction port on the first side of the impeller 1 The cover plate inclination angle T of the suction inlet on the second side of the impeller 2 Impeller inlet diameter D' 1 Impeller exit diameter D' 2 (ii) a Calculated as follows:
Figure BDA0003714152870000033
Figure BDA0003714152870000034
Figure BDA0003714152870000035
T 1 ＝T 2 ＝80°～87°；
in the formula: g-gravity acceleration, H-pump first-stage head, and Q-pump first-stage flow;
4) determining blade thickness sigma of an impeller flow channel 1 Blade exit angle beta 1 Blade wrap angle
Figure BDA0003714152870000036
Flow channel central line wrap angle
Figure BDA0003714152870000037
Calculated according to the following formula:
σ 1 ＝4～8mm；
β 1 ＝10°～30°；
Figure BDA0003714152870000038
Figure BDA0003714152870000039
5) maintaining impeller exit velocity c 2 And outlet dynamic fluid flow angle alpha 2 The change is not changed;
6) ensuring the absolute liquid flow angle alpha of the first-stage volute inlet 3 Is a constant value;
7) keeping the impeller with a slightly lower lift coefficient psi, preventing rotating stall, the lift coefficient psi is calculated as follows:
Figure BDA00037141528700000310
in the formula: g-acceleration of gravity, H-first pump lift, u 2 -peripheral speed at the outer diameter of the impeller;
8) blades on two sides of the double-suction impeller are alternately and crossly arranged at the outer diameter part and comprise a blade pressure surface positioned on the first side of the double-suction impeller, a blade suction surface positioned on the first side of the double-suction impeller, a blade pressure surface positioned on the second side of the double-suction impeller and a blade suction surface positioned on the second side of the double-suction impeller, the fluid dynamic reaction force on the blades is strictly controlled, and a local pressure coefficient C is introduced p And coefficient of overall lift C L Is controlled by two functions of pressure coefficient C p Calculated according to the following formula:
Figure BDA0003714152870000041
coefficient of pressure C L Calculated according to the following formula:
Figure BDA0003714152870000042
in the formula: c. C u -tangential velocity component, Z-impeller blade number, r-radial component in cylindrical coordinate system, x-axial component in cylindrical coordinate system, B-blade height, f b -new blade distribution coefficient, w 1tip 、w 2 -relative velocity vector, u 2 -peripheral speed at the impeller outer diameter, L-impeller height;
9) two groups of flow channels which are arranged at suction ports at two ends of the double-suction impeller are symmetrically arranged on the middle shaft surface of the double-suction impeller and deflect by a certain angle gamma, and the deflection angle gamma is calculated according to the following formula:
γ＝2π/Z；
in the formula: z-number of leaves;
10) determining a flow coefficient
Figure BDA0003714152870000043
The efficiency eta and the power coefficient lambda are calculated according to the following formulas:
Figure BDA0003714152870000044
Figure BDA0003714152870000045
Figure BDA0003714152870000046
in the formula: c-axial Power, Δ P tot Total pressure, ω -angular rotation velocity.
The double-suction impeller structure for the multistage centrifugal pump and the design method thereof can effectively improve the cavitation resistance of the centrifugal pump through the design of the inner edge of the mouth ring and the concave-convex part. By the design method, the cavitation resistance of the centrifugal pump can be improved, so that the overall efficiency of the centrifugal pump is improved.
Drawings
FIG. 1 is a schematic view of a prior art double suction impeller configuration;
FIG. 2 is a schematic view of a double suction impeller according to the present invention;
FIG. 3 is a schematic structural view of a double suction impeller according to the present invention;
FIG. 4 is a schematic structural view of a double suction impeller according to the present invention;
FIG. 5 is a schematic view of the structure of the double suction impeller of the present invention;
FIG. 6 is a schematic structural view of a double suction impeller according to the present invention;
FIG. 7 is a schematic view of the structure of the double suction impeller of the present invention;
fig. 8 is a schematic structural view of the double suction impeller of the present invention.
In the figure: first vane 10, first cover plate 11, first outlet 12, first porting ring 13, first impeller flowpath P1, first porting ring outer edge 131, first porting ring inner edge 132, first cover plate inner sidewall 111, relief 112, second vane 20, second cover plate 21, second outlet 22, second porting ring 23, second impeller flowpath P1, second porting ring inner edge 232, hub 30, first hub 31, second hub 32, hub axial end outer edge 33, groove/notch 331.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 2 to 7, a double suction impeller structure for a multistage centrifugal pump includes first blades 10, a first cover plate 11, a first outlet 12, a first porting ring 13, a first impeller flow passage P1, second blades 20, a second cover plate 21, a second outlet 22, a second porting ring 23, a second impeller flow passage P2, and a hub 30, where the hub 30 includes a first hub 31 and a second hub 32 symmetrically arranged, the first blades 10 and the second blades 20 are symmetrically arranged, a first impeller flow passage P1 is formed between two adjacent first blades 10, a second rotating passage P2 is formed between two adjacent second blades 20, an outlet end of the first impeller flow passage P1 has the first outlet 12, an outlet end of the second impeller flow passage P2 has the second outlet 22, two axial ends of the first outlet 12 are respectively flush with two axial ends of the second outlet 22 and have the same axial width, and the first outlet 12 and the second outlet 22 are alternately arranged in a circumferential direction, the end of the first cover plate 11 has a first collar 13, and the end of the second cover plate 21 has a second collar 23, wherein: the first orifice ring 13 has a first orifice ring outer edge 131 and a first orifice ring inner edge 132, the first orifice ring outer edge 131 is circular, the first orifice ring inner edge 132 is a first ellipse, the second orifice ring 23 has a second orifice ring outer edge and a second orifice ring inner edge 232, the second orifice ring outer edge is circular, the second orifice ring inner edge 232 is a second ellipse, and the major axis (2a) of the first ellipse is perpendicular to the major axis of the second ellipse.
As shown in fig. 4-6, further, the axial end of the hub 30 has a hub axial end outer edge 33, the hub axial end outer edge 33 having a radius R, the first ellipse and/or the second ellipse having a major axis a, a minor axis b, a ═ 1.05-1.2) b, preferably 1.1; r ═ (0.5-0.65) a, preferably 0.6.
The double-suction impeller structure for the multistage centrifugal pump can effectively improve the cavitation resistance of the centrifugal pump through the design of the inner edge of the opening ring.
Further, the outer peripheral surface of the hub axial end outer edge 33 is provided with a plurality of grooves 331, and the plurality of grooves 331 are evenly distributed in the circumferential direction. The radial depth of the groove 331 is 0.25-0.4 times the radial thickness of the first hub 31, and the axial depth of the groove 331 is 0.75-1.5 times the radial thickness of the first hub 31.
The double-suction impeller structure for the multistage centrifugal pump can further/better improve the cavitation resistance of the centrifugal pump through the design that the grooves 331 are matched with the inner edge of the opening ring.
Further, the first cover 11 has a first cover inner sidewall 111, and a concave-convex portion 112 is provided on/on the surface of the first cover inner sidewall 111 and in the first impeller flow path P1, the concave-convex portion 112 is wavy, and the concave-convex portion 112 extends from the downstream of the first porting ring 13 to the first outlet 12.
Further, in the circumferential direction, the concave-convex portion 112 is provided only in a region/position corresponding to the minor axis of the first ellipse, which is 60 to 150 ° in the circumferential direction.
Further, the second shroud 21 has a second shroud inner side wall, and a second concave-convex portion is provided on/on the second shroud inner side wall surface and in the second vane passage P2, the second concave-convex portion being wavy, the second concave-convex portion extending from the downstream of the second mouth ring 23 to the second outlet 22, and having the same concave-convex structure as the first shroud inner side wall 111.
The double-suction impeller structure for the multistage centrifugal pump of the present invention can further improve the cavitation resistance of the centrifugal pump by the design of the concave-convex portion 112.
A design method of a double-suction impeller structure for a multistage centrifugal pump comprises the following steps:
during design/calculation, the numerical part of each parameter/each variable is measured to carry out design/calculation;
1) determining the specific speed n of the double suction impeller q Calculated in the following way:
Figure BDA0003714152870000071
in the formula: f. of q -impeller suction port number; q BEP -rated flow of the multistage pump; n-rated rotation speed; h BEP -designing the lift;
2) determining a flow channel central line r of an impeller flow channel; the central line of the flow channel is a variable Archimedes spiral line and is calculated according to the following equation:
Figure BDA0003714152870000072
in the formula: r-original flow channel centerline; d 2 -a flow channel outlet diameter; theta-polar angle;
Figure BDA0003714152870000073
-flow channel centerline wrap angle;
3) determining the width b of the outlet and the inclination angle T of the cover plate of the suction port on the first side of the impeller 1 The cover plate inclination angle T of the suction inlet on the second side of the impeller 2 Impeller inlet diameter D 1 ', impeller Outlet diameter D' 2 (ii) a Calculated as follows:
Figure BDA0003714152870000074
Figure BDA0003714152870000075
Figure BDA0003714152870000076
T 1 ＝T 2 ＝80°～87°；
in the formula: g-gravity acceleration, H-pump head lift, Q-pump head flow and n-rated rotating speed;
4) determining blade thickness sigma of an impeller flow channel 1 Blade exit angle beta 1 Blade wrap angle
Figure BDA0003714152870000077
Flow channel central line wrap angle
Figure BDA0003714152870000078
Calculated according to the following formula:
σ 1 ＝4～8mm；
β 1 ＝10°～30°；
Figure BDA0003714152870000079
Figure BDA00037141528700000710
5) maintaining impeller exit velocity c 2 And outlet dynamic fluid flow angle alpha 2 The change is not changed;
6) ensuring the absolute liquid flow angle alpha of the first-stage volute inlet 3 Is a constant value;
7) keeping the impeller with a slightly lower lift coefficient psi, preventing rotating stall, the lift coefficient psi is calculated as follows:
Figure BDA0003714152870000081
in the formula: g-acceleration of gravity, H-first pump lift, u 2 -peripheral speed at the outer diameter of the impeller;
8) blades on two sides of the double-suction impeller are alternately and crossly arranged at the outer diameter part and comprise a blade pressure surface positioned on the first side of the double-suction impeller, a blade suction surface positioned on the first side of the double-suction impeller, a blade pressure surface positioned on the second side of the double-suction impeller and a blade suction surface positioned on the second side of the double-suction impeller, the fluid dynamic counter force on the blades is strictly controlled, and a local pressure coefficient C is introduced p And coefficient of overall lift C L Is controlled by two functions of pressure coefficient C p Calculated according to the following formula:
Figure BDA0003714152870000082
coefficient of pressure C L Calculated according to the following formula:
Figure BDA0003714152870000083
in the formula: c. C u -tangential velocity component, Z-impeller blade number, r-radial component in cylindrical coordinate system, x-axial component in cylindrical coordinate system, B-blade height, f b -new blade distribution coefficient, w 1tip 、w 2 -relative velocity vector, u 2 -peripheral speed at the impeller outer diameter, L-impeller height;
9) two groups of flow channels which are arranged at suction ports at two ends of the double-suction impeller are symmetrically arranged about the central axis of the double-suction impeller and deflect a certain angle gamma, and the deflection angle gamma is calculated according to the following formula:
γ＝2π/Z；
in the formula: z-number of leaves;
10) determining a flow coefficient
Figure BDA0003714152870000084
The efficiency eta and the power coefficient lambda are calculated according to the following formulas:
Figure BDA0003714152870000085
Figure BDA0003714152870000086
Figure BDA0003714152870000087
in the formula: c-axial Power, Δ P tot Total pressure, ω -angular rotation velocity.
The double-suction impeller structure for the multistage centrifugal pump and the design method thereof can effectively improve the cavitation resistance of the centrifugal pump through the design of the inner edge of the mouth ring and the concave-convex part. By the design method, the cavitation resistance of the centrifugal pump can be improved, so that the overall efficiency of the centrifugal pump is improved.
The above-described embodiments are illustrative of the present invention and not restrictive, it being understood that various changes, modifications, substitutions and alterations can be made herein without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims (9)

1. A double-suction impeller structure for a multistage centrifugal pump comprises first blades (10), a first cover plate (11), a first outlet (12), a first opening ring (13), a first impeller flow passage (P1), second blades (20), a second cover plate (21), a second outlet (22), a second opening ring (23), a second impeller flow passage (P2) and a hub (30), wherein the hub comprises a first hub part (31) and a second hub part (32) which are symmetrically arranged, the first blades and the second blades are symmetrically arranged, the first impeller flow passage (P1) is formed between every two adjacent first blades, the second impeller flow passage (P2) is formed between every two adjacent second blades (20), the outlet end of the first impeller flow passage is provided with the first outlet, the outlet end of the second impeller flow passage is provided with the second outlet, the axial two ends of the first outlet are respectively flush with the axial two ends of the second outlet and have the same axial width, in the circumference, first export and second export are arranged alternately/interval, and the end of first apron has first choma, and the end of second apron has second choma, its characterized in that: the first opening ring (13) is provided with a first opening ring outer edge (131) and a first opening ring inner edge (132), the first opening ring outer edge is circular, the first opening ring inner edge is in a first ellipse shape, the second opening ring (23) is provided with a second opening ring outer edge and a second opening ring inner edge (232), the second opening ring outer edge is circular, the second opening ring inner edge is in a second ellipse shape, and the long axis (2a) of the first ellipse shape is perpendicular to the long axis of the second ellipse shape.
2. A double suction impeller construction for a multistage centrifugal pump according to claim 1, characterized in that the axial end of the hub (30) has a hub axial end outer rim (33) with a radius R, the first and/or second ellipse having a major semi-axis a, a minor semi-axis b, (1.05-1.2) b, R ═ 0.5-0.65) a.
3. A double suction impeller structure for a multistage centrifugal pump according to claim 2, wherein the outer peripheral surface of the hub axial end portion outer rim (33) is provided with a plurality of grooves (331) distributed in the circumferential direction.
4. A double suction impeller structure for a multistage centrifugal pump according to claim 3, wherein the radial depth of the groove (331) is 0.25 to 0.4 times the radial thickness of the first hub portion (31), and the axial depth of the groove (331) is 0.5 to 2 times the radial thickness of the first hub portion (31).
5. The double suction impeller structure for a multistage centrifugal pump as claimed in claim 2, wherein said first shroud (11) has a first shroud inner side wall (111) on the surface of which irregularities (112) are provided in the first impeller flow passage (P1), the irregularities being wavy, the irregularities extending from downstream of the first porting ring (13) to the first outlet (12).
6. A double suction impeller structure for a multistage centrifugal pump according to claim 5, wherein the concavo-convex portion (112) is provided only in a region corresponding to a minor axis of the first ellipse in the circumferential direction, the region being 60 to 150 ° in the circumferential direction.
7. The double suction impeller structure for a multistage centrifugal pump as claimed in claim 6, wherein said second shroud (21) has a second shroud inner side wall, on the second shroud inner side wall surface and in the second impeller channel (P2) are provided second concavities and convexities, the second concavities and convexities being wavy, the second concavities and convexities extending from downstream of the second port ring to the second outlet; in the circumferential direction, the second concave-convex part is only arranged in a region corresponding to the short axis of the second ellipse, the region is 60-150 degrees in the circumferential direction, and the structure has the same concave-convex part structure with the inner side wall of the first cover plate.
8. A method of designing a double suction impeller structure for a multistage centrifugal pump according to claim 7, comprising the steps of:
during design/calculation, each parameter/each variable is measured, and the numerical part is designed/calculated;
1) determining the specific speed n of the double-suction impeller q Calculated in the following way:
Figure FDA0003714152860000021
in the formula: f. of q -impeller suction port number; q BEP -rated flow of the multistage pump; n-rated rotation speed; h BEP -designing the lift;
2) determining a flow channel central line r of an impeller flow channel; the central line of the flow channel is a variable Archimedes spiral line and is calculated according to the following equation:
Figure FDA0003714152860000022
in the formula: r-original flow channel centerline; d 2 -a flow channel outlet diameter; theta-polar angle;
Figure FDA0003714152860000023
-flow channel centerline wrap angle;
3) determining the width b of the outlet and the inclination angle T of the cover plate of the suction port on the first side of the impeller 1 The cover plate inclination angle T of the suction inlet on the second side of the impeller 2 Impeller inlet diameter D' 1 Impeller exit diameter D' 2 (ii) a Calculated as follows:
Figure FDA0003714152860000024
Figure FDA0003714152860000025
Figure FDA0003714152860000026
T 1 ＝T 2 ＝80°～87°；
in the formula: g-gravity acceleration, H-pump head, Q-pump head flow and n-rated rotating speed;
4) determining blade thickness sigma of an impeller flow channel 1 Blade exit angle beta 1 Blade wrap angle
Figure FDA0003714152860000031
Flow channel midline wrap angle
Figure FDA0003714152860000032
Calculated according to the following formula:
σ 1 ＝4～8mm；
β 1 ＝10°～30°；
Figure FDA0003714152860000033
Figure FDA0003714152860000034
5) maintaining impeller exit velocity c 2 And the outlet dynamic flow angle alpha 2 The change is not changed;
6) ensuring the absolute liquid flow angle alpha of the first-stage volute inlet 3 Is a constant value;
7) keeping the impeller with a slightly lower lift coefficient psi, preventing rotating stall, the lift coefficient psi is calculated as follows:
Figure FDA0003714152860000035
in the formula: g-acceleration of gravity, H-first pump lift, u 2 -peripheral speed at the outer diameter of the impeller.
9. The design method of claim 8, further comprising:
8) blades on two sides of the double-suction impeller are alternately and crossly arranged at the outer diameter part and comprise a blade pressure surface positioned on the first side of the double-suction impeller, a blade suction surface positioned on the first side of the double-suction impeller, a blade pressure surface positioned on the second side of the double-suction impeller and a blade suction surface positioned on the second side of the double-suction impeller, the fluid dynamic counter force on the blades is strictly controlled, and a local pressure coefficient C is introduced p And coefficient of overall lift C L Is controlled by two functions of pressure coefficient C p Calculated according to the following formula:
Figure FDA0003714152860000036
coefficient of pressure C L Calculated according to the following formula:
Figure FDA0003714152860000037
in the formula: c. C u -tangential velocity component, Z-impeller blade number, r-radial component in cylindrical coordinate system, x-axial component in cylindrical coordinate system, B-blade height, f b -new blade distribution coefficient, w 1tip 、w 2 -relative velocity vector, u 2 -peripheral speed at the impeller outer diameter, L-impeller height;
9) two groups of flow channels which are arranged at suction ports at two ends of the double-suction impeller are symmetrically arranged on the middle shaft surface of the double-suction impeller and deflect by a certain angle gamma, and the deflection angle gamma is calculated according to the following formula:
γ＝2π/Z；
in the formula: z-number of leaves;
10) determining a flow coefficient
Figure FDA0003714152860000041
The efficiency eta and the power coefficient lambda are calculated according to the following formulas:
Figure FDA0003714152860000042
Figure FDA0003714152860000043
Figure FDA0003714152860000044
in the formula: c-axial Power, Δ P tot Total pressure, ω -angular rotation velocity.
CN202210732020.2A 2022-06-09 2022-06-26 Double-suction impeller structure for multistage centrifugal pump and design method thereof Pending CN115013318A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116379000A (en) * 2023-03-17 2023-07-04 中交疏浚技术装备国家工程研究中心有限公司 Non-axisymmetric end wall modeling of dredge mud pump impeller
CN116464664A (en) * 2023-05-31 2023-07-21 江苏大学流体机械温岭研究院 Water and fertilizer integrated system and fertilizer pump thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116379000A (en) * 2023-03-17 2023-07-04 中交疏浚技术装备国家工程研究中心有限公司 Non-axisymmetric end wall modeling of dredge mud pump impeller
CN116379000B (en) * 2023-03-17 2024-04-09 中交疏浚技术装备国家工程研究中心有限公司 Non-axisymmetric end wall modeling of dredge mud pump impeller
CN116464664A (en) * 2023-05-31 2023-07-21 江苏大学流体机械温岭研究院 Water and fertilizer integrated system and fertilizer pump thereof
CN116464664B (en) * 2023-05-31 2024-04-02 台州科技职业学院 Water and fertilizer integrated system and fertilizer pump thereof

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