Design method of centrifugal pump multiphase impeller for along the Yellow River basin

Abstract

The present application relates to the technical field of horizontal split centrifugal pump used in the irrigation engineering along the Yellow River basin, in particular to a design method of centrifugal pump multi-phase flow impeller used in the Yellow River basin, which comprises the following steps: S1, determining the hydraulic parameter requirements of the design task; S2, calculating the size range of the axial flow channel by the velocity coefficient method; S3, designing the axial profile and the blade space profile; S4, simulating the axial profile and the blade space profile of step S3 by using CFD software; S5, testing the external characteristics of the hydraulic model of the pump; the present application designs the convex back bending of the blade inlet edge, so that the liquid flow is powered in advance, the inlet impact and vortex are reduced; the v-shaped trailing edge is adopted at the blade outlet edge, which greatly improves the flow capacity of the impeller; the sand discharge groove structure is designed at the impeller cover plate before entering the sealing gap, so as to avoid the solid particles from entering the sealing ring, and fundamentally solve the wear problem of the sealing ring of the impeller; the impeller designed by the present application has high efficiency, excellent cavitation performance and strong flow capacity in the operation of the irrigation engineering along the Yellow River basin.

Description

Technical Field

[0001] This invention relates to the technical field of horizontal split-case centrifugal pumps used in irrigation projects along the Yellow River basin, specifically a design method for a multiphase flow impeller for centrifugal pumps used along the Yellow River basin. Background Technology

[0002] In the actual transportation process of the Yellow River Basin irrigation and pumping project, horizontal split-case centrifugal pumps generally have obvious "flow drop" phenomenon, which has become a major problem for pumps used in the Yellow River Basin irrigation and pumping project.

[0003] The sediment content of the Yellow River water will cause sediment to accumulate at the leading edge of the impeller blade inlet and the back of the blade outlet of the horizontal split-case centrifugal pump. This will increase the number of vortices in the impeller flow channel, resulting in a decrease in the impeller's flow capacity and a reduction in the pump's efficiency and cavitation performance.

[0004] The existing technology patent "A Multi-condition Design Method for Impeller of Multiphase Mixed-Transport Axial Flow Pump", patent number: CN201410481735.0 mentions a multi-condition design method for impeller of multiphase mixed-transport axial flow pump. However, the method proposed in this patent is a design method for axial flow pump impellers. This invention focuses on multiphase non-clogging impellers applied to centrifugal pumps used in the Yellow River diversion basin. Summary of the Invention

[0005] The purpose of this invention is to provide a design method for a multiphase flow impeller for centrifugal pumps used in the Yellow River Basin, which solves the problem of obvious "flow drop" and wear at the impeller sealing ring position that are common in horizontal split-case centrifugal pumps during the actual transportation process of irrigation projects in the Yellow River Basin.

[0006] To solve the above-mentioned technical problems, the present invention provides a design method for a multiphase flow impeller for a centrifugal pump used in the Yellow River Basin, comprising the following steps:

[0007] S1. Determine the hydraulic parameter requirements for the design task, including flow rate Q, head H, rotational speed n, and required net positive suction head (NPSHr);

[0008] S2. Calculate the axial flow channel size range using the velocity coefficient method based on the hydraulic parameter requirements of the design task determined in step S1.

[0009] S3. Based on the axial flow channel size range calculated in step S2, design the axial profile and blade spatial profile.

[0010] S4. Use CFD software to simulate the shaft profile and blade spatial profile of step S3. If the flow rate Q, head H, efficiency η and shaft power Pa after simulation meet the requirements of step S1 and step S2, proceed to the next step. If the flow rate Q, head H, efficiency η and shaft power Pa after simulation do not meet the requirements of step S1 and step S2, repeat step S3.

[0011] S5. External characteristic test of the pump's hydraulic model. After processing, dynamic balance test, static pressure test and hydraulic performance test are carried out. The hydraulic performance test includes QH test, Q-η test and Q-Pa test.

[0012] Furthermore, step S2 includes the following steps:

[0013] S2.1. Calculate the specific speed n s The calculation formula is:

[0014]

[0015] In the formula: n s Specific speed; n is rotational speed; Q is flow rate; H is head;

[0016] S2.2. Calculate the efficiency η, the calculation formula is:

[0017] ;

[0018] In the formula: η represents efficiency; η h For hydraulic efficiency; η v For volumetric efficiency; η m For mechanical efficiency;

[0019] Hydraulic efficiency η h The calculation formula is:

[0020] ;

[0021] Volumetric efficiency η v The calculation formula is:

[0022] ;

[0023] Mechanical efficiency η m The calculation formula is:

[0024] ;

[0025] S2.3. Calculate the shaft power Pa using the following formula:

[0026] ;

[0027] In the formula: Pa is shaft power; Q is flow rate; H is head; η is efficiency;

[0028] S2.4. Calculate the power Pn, using the following formula:

[0029] ;

[0030] In the formula: Pn is the power of the belt; Pa is the shaft power;

[0031] S2.5. Calculate the torque Mn using the following formula:

[0032] ;

[0033] In the formula: Mn is torque; Pn is power output; n is rotational speed;

[0034] S2.6. Calculate the minimum shaft diameter d min The calculation formula is:

[0035] ;

[0036] In the formula: d min Mn is the minimum shaft diameter; Mn is the torque. The allowable stress of the material;

[0037] S2.7. Calculate the inlet equivalent diameter D0 using the following formula:

[0038] ;

[0039] In the formula: D0 is the equivalent inlet diameter; Q is the flow rate; n is the rotational speed; K0 is the coefficient;

[0040] S2.8. Calculate the impeller outer diameter D2 using the following formula:

[0041] ;

[0042] In the formula: KD2 is a coefficient; Q is the flow rate; n is the rotational speed; ;n s Specific speed;

[0043] S2.9. Calculate the outlet width b2 using the following formula:

[0044] ;

[0045] In the formula: b2 is the outlet width; Q is the flow rate; n is the rotational speed; ;n s Specific speed;

[0046] S2.10. Calculate the impeller inlet diameter D j The calculation formula is:

[0047] ;

[0048] In the formula: D j D0 is the impeller inlet diameter; D0 is the equivalent inlet diameter; d h The diameter of the wheel hub;

[0049] dh The calculation formula is:

[0050] ;

[0051] In the formula: d i The shaft diameter at the impeller mounting location. ;

[0052] S2.11. Calculate the blade exit angle β2 using the following formula:

[0053] ;

[0054] In the formula: n s Specific speed.

[0055] Furthermore, in step S2.7, the value range of K0 is as follows: when efficiency is the primary consideration, K0 = 3.5~4.0; when efficiency and cavitation are considered simultaneously, K0 = 4.0~4.5; when cavitation is the primary consideration, K0 = 4.5~5.5.

[0056] Furthermore, step S3 includes the following steps:

[0057] S3.1. In the CF turbo software, input the single-suction impeller flow rate, head, speed, density, inlet pre-swirl status, and rotation direction, and click "OK" to proceed to the next step;

[0058] S3.2. Input dimensionless parameters, hydraulic efficiency, mechanical efficiency, and volumetric efficiency; CF turbo software generates the initial main structural parameters of the impeller: minimum shaft diameter, hub diameter, inlet diameter, impeller outer diameter, and outlet width;

[0059] S3.3. Design the axial profile: front cover plate, rear cover plate and convex inlet edge. The inlet edge profile is controlled by the intersection of the inlet edge profile with the front cover plate profile, the intersection of the inlet edge with the flow channel centerline, and the intersection of the inlet edge profile with the rear cover plate profile. You can change the coordinate values ​​of the three control points by right-clicking on the control points or directly drag the control points with the mouse to change the position and shape of the front and rear cover plate profiles, inlet edge and outlet edge.

[0060] Furthermore, in step S4, the final formed convex S-shaped inlet edge profile, front and rear cover plate profiles are Bézier curves.

[0061] The blades of this invention are twisted near the front cover plate, allowing the liquid flow to receive work earlier and reducing inlet impact and vortices. To avoid the formation of low-pressure eddies and boundary layer separation within the impeller, the degree of twisting near the front cover plate at the blade inlet is increased, thereby increasing the distance between the blades at the front cover plate of the impeller. This is beneficial for improving the flow capacity for transporting impurities, thus improving efficiency.

[0062] Furthermore, when designing impellers using CF Turbo, the following steps are taken to check the diffusion between blades and the velocity variation:

[0063] Step 1: Determine whether the cross-sectional area of ​​the axial surface exhibits a perfect monotonically increasing characteristic to avoid local maximum or minimum values;

[0064] Step 2: Determine the static moment characteristic curve. The static moment values ​​at the outlets of the front and rear cover plates should be approximately equal. Using the graphical integration method, divide the line connecting the centers of the inscribed circles of the flow channel from the blade inlet to the outlet into i equal parts. Divide the length of each segment ΔS... i Multiply by the radius R from the center of the inscribed circle of the flow channel to the impeller axis. i Adding these products together gives the static moment, as shown in the following formula:

[0065] ;

[0066] In the formula: s is the static moment; ΔS i R is the length of the line connecting the centers of the i-th inscribed circle; i The radius from the center of the inscribed circle to the impeller axis;

[0067] Step 3: Determine the axial velocity to avoid areas where the local axial radius is 0;

[0068] Step 4: Determine the characteristics of the axial flow field.

[0069] When using CF Turbo for impeller design, the diffusion between blades and velocity variations are checked. During impeller shaft surface design, CF Turbo can display real-time curves of changes in the cross-sectional area of ​​the water passage, static moment, and shaft surface velocity, facilitating shaft surface performance verification. Simultaneously, two-dimensional flow field numerical prediction is performed on the impeller shaft surface, calculating the streamline distribution, velocity distribution, and contour information.

[0070] The profiles of typical impeller front and rear cover plates are in the form of "circular arc + straight line, straight line", etc. It is basically impossible to achieve a perfect monotonically increasing characteristic of the cross-sectional area of ​​the shaft surface by simply using circular arc and straight line methods. The cover plate profile of the multiphase non-blocking impeller in this patent is a Bézier curve, which can better control the shape of the impeller shaft surface and the flow channel area, which is the unique feature of this impeller.

[0071] The impeller designed by the present invention for a multiphase flow impeller of a centrifugal pump used in the Yellow River Basin is a double-suction impeller with a V-shaped trailing edge design at the blade outlet. The included angle between the symmetrical blades of the impeller is 100°, that is, the included angle between the blade and the cover plate is 130°.

[0072] The double-suction impeller blades feature a V-shaped trailing edge design at the outlet. When pumping Yellow River water containing silt, solid-liquid separation often occurs in the impeller. To improve the flow conditions within the impeller, our company has developed a unique outlet velocity triangle and adopted a V-shaped trailing edge outlet structure design. Traditionally, the blades are arranged perpendicularly to the cover plate. To meet the principle of large wall angles, the included angle between the symmetrical blades of this multiphase flow double-suction impeller is 100°, meaning the included angle between the blades and the cover plate is 130°. This is a unique feature of this impeller. This design more effectively meets the flow conditions within the impeller under silt-containing conditions, effectively reducing losses, improving the impeller's hydraulic efficiency, and avoiding hydraulic losses caused by impact and flow separation.

[0073] This invention relates to a design method for a multiphase flow impeller in a centrifugal pump along the Yellow River basin. The impeller inlet ring of the impeller is positioned at the junction with the front cover plate, where a sand discharge groove is located. This sand discharge groove is situated at the impeller cover plate before entering the sealing gap, and the radius of the annular surface of the sand discharge groove is [missing information]. When a medium containing solid particles enters the sand discharge tank, the velocity of the solid particles decreases, the centrifugal force decreases, and stratification occurs, eventually throwing the solid particles out to achieve the purpose of sand discharge. This prevents solid particles from entering the sealing ring and fundamentally solves the problem of impeller sealing ring wear.

[0074] The beneficial effects of this invention are:

[0075] 1. Multi-point control of the blade's Bézier curve and full-domain control of the impeller streamline result in more uniform flow within the impeller. The Bézier curve is a smooth curve drawn based on the coordinates of four arbitrary points. The front and rear cover plates and the inlet edge of the multiphase impeller in this patent are all designed using Bézier curves.

[0076] 2. Based on the dynamic response characteristics of fluid-structure interaction, a reasonable impeller cover curvature radius is selected to reduce fluid boundary layer separation;

[0077] 3. Study the impeller flow law and multi-parameter matching law under extreme working conditions, and select an impeller outlet angle with better matching to significantly improve the impeller flow capacity;

[0078] 4. The blade inlet edge is designed with a convex back bend to allow the liquid flow to receive work in advance, reducing inlet impact and vortex;

[0079] 5. By employing an incomplete sensitivity optimization method, the parameters of the impeller and flow channel are optimized, thereby reducing the flow velocity inside the impeller. This can avoid or mitigate cavitation and improve the impeller's flow capacity.

[0080] 6. The blade inlet edge adopts a unique convex back bend design, and the blade outlet edge adopts a V-shaped trailing edge design, which greatly improves the impeller's flow capacity;

[0081] 7. Design a sand discharge groove structure at the impeller cover plate before entering the sealing gap to prevent solid particles from entering the sealing ring and fundamentally solve the wear problem of the impeller sealing ring;

[0082] 8. The designed impeller has high efficiency, excellent cavitation performance, and strong flow capacity in the Yellow River Basin irrigation and pumping project. Attached Figure Description

[0083] Figure 1 This is a flowchart of the steps of the present invention;

[0084] Figure 2 An unfolded diagram of the impeller shape designed for this invention;

[0085] Figure 3 This is a partial structural diagram of the impeller sand discharge trough designed in this invention;

[0086] Figure 4 This is a schematic diagram of the impeller shaft surface design using CF turbo software in this invention.

[0087] Figure 5 This is the final shape diagram of the axial surface designed using CF turbo software in this invention.

[0088] Figure 6 A cross-sectional area diagram of the impeller for this invention;

[0089] Figure 7 The static torque characteristic curves of the front and rear cover plate outlets of the impeller designed for this invention are shown.

[0090] Figure 8 The axial velocity diagram of the impeller is designed for this invention;

[0091] Figure 9 This is a numerical prediction diagram of the two-dimensional flow field on the impeller shaft surface according to the present invention;

[0092] Figure 10 This is a schematic diagram of the pump arrangement in Embodiment 2 of the present invention;

[0093] Figure 11 This is a flow rate change curve diagram from Embodiment 2 of the present invention;

[0094] Figure 12 This is a power variation curve diagram from Embodiment 2 of the present invention;

[0095] Figure 13 This is a comparison chart of energy consumption per unit flow rate in Embodiment 2 of the present invention;

[0096] Figure 14 This is a graph showing the flow rate variation of pumps #16, #3, and #9 in Embodiment 2 of the present invention.

[0097] Figure 15This is a power variation curve of pumps #16, #3, and #9 in Embodiment 2 of the present invention;

[0098] Figure 16 This is a comparison chart of the energy consumption per unit flow rate of pumps #16, #3, and #9 in Embodiment 2 of the present invention. Detailed Implementation

[0099] like Figure 1 The present invention provides a design method for a multiphase flow impeller for a centrifugal pump used in the Yellow River basin, comprising the following steps:

[0100] S1. Determine the hydraulic parameter requirements for the design task, including flow rate Q, head H, rotational speed n, and required net positive suction head (NPSHr);

[0101] S2. Calculate the axial flow channel size range using the velocity coefficient method based on the hydraulic parameter requirements of the design task determined in step S1.

[0102] S2.1. Calculate the specific speed n s The calculation formula is:

[0103]

[0104] In the formula: n s Specific speed; n is rotational speed; Q is flow rate; H is head;

[0105] S2.2. Calculate the efficiency η, the calculation formula is:

[0106] ;

[0107] In the formula: η represents efficiency; η h For hydraulic efficiency; η v For volumetric efficiency; η m For mechanical efficiency;

[0108] Hydraulic efficiency η h The calculation formula is:

[0109] ;

[0110] Volumetric efficiency η v The calculation formula is:

[0111] ;

[0112] Mechanical efficiency η m The calculation formula is:

[0113] ;

[0114] S2.3. Calculate the shaft power Pa using the following formula:

[0115] ;

[0116] In the formula: Pa is shaft power; Q is flow rate; H is head; η is efficiency;

[0117] S2.4. Calculate the power Pn, using the following formula:

[0118] ;

[0119] In the formula: Pn is the power of the belt; Pa is the shaft power;

[0120] S2.5. Calculate the torque Mn using the following formula:

[0121] ;

[0122] In the formula: Mn is torque; Pn is power output; n is rotational speed;

[0123] S2.6. Calculate the minimum shaft diameter d min The calculation formula is:

[0124] ;

[0125] In the formula: d min Mn is the minimum shaft diameter; Mn is the torque. The allowable stress of the material;

[0126] S2.7. Calculate the inlet equivalent diameter D0 using the following formula:

[0127] ;

[0128] In the formula: D0 is the equivalent inlet diameter; Q is the flow rate; n is the rotational speed; K0 is a coefficient; the value range of K0 is: K0 = 3.5~4.0 when efficiency is the primary consideration; K0 = 4.0~4.5 when efficiency and cavitation are considered simultaneously; K0 = 4.5~5.5 when cavitation is the primary consideration.

[0129] S2.8. Calculate the impeller outer diameter D2 using the following formula:

[0130] ;

[0131] In the formula: KD2 is a coefficient; Q is the flow rate; n is the rotational speed; ;n s Specific speed;

[0132] S2.9. Calculate the outlet width b2 using the following formula:

[0133] ;

[0134] In the formula: b2 is the outlet width; Q is the flow rate; n is the rotational speed; ;n s Specific speed;

[0135] S2.10. Calculate the impeller inlet diameter D j The calculation formula is:

[0136] ;

[0137] In the formula: D j D0 is the impeller inlet diameter; D0 is the equivalent inlet diameter; d h The diameter of the wheel hub;

[0138] d h The calculation formula is:

[0139] ;

[0140] In the formula: d i The shaft diameter at the impeller mounting location. ;

[0141] S2.11. Calculate the blade exit angle β2 using the following formula:

[0142] ;

[0143] In the formula: n s Specific speed;

[0144] S3. Based on the axial flow channel size range calculated in step S2, design the axial profile and blade spatial profile.

[0145] S3.1. In the CF turbo software, input the single-suction impeller flow rate, head, speed, density, inlet pre-swirl status, and rotation direction, and click "OK" to proceed to the next step;

[0146] S3.2. Input dimensionless parameters, hydraulic efficiency, mechanical efficiency, and volumetric efficiency; CF turbo software generates the initial main structural parameters of the impeller: minimum shaft diameter, hub diameter, inlet diameter, impeller outer diameter, and outlet width;

[0147] S3.3. Design the axial profile: front cover plate, rear cover plate, and protruding inlet edge. The inlet edge profile is controlled by the intersection of the inlet edge profile with the front cover plate profile, the intersection of the inlet edge with the flow channel centerline, and the intersection of the inlet edge profile with the rear cover plate profile. You can change the coordinate values ​​of the three control points by right-clicking on the control points or directly drag the control points with the mouse to change the position and shape of the front and rear cover plate profiles, inlet edge, and outlet edge.

[0148] S4. Use CFD software to simulate the shaft profile and blade spatial profile of step S3. If the flow rate Q, head H, efficiency η and shaft power Pa after simulation meet the requirements of step S1 and step S2, proceed to the next step. If the flow rate Q, head H, efficiency η and shaft power Pa after simulation do not meet the requirements of step S1 and step S2, repeat step S3.

[0149] S5. External characteristic test of the pump's hydraulic model. After processing, dynamic balance test, static pressure test and hydraulic performance test are carried out. The hydraulic performance test includes QH test, Q-η test and Q-Pa test.

[0150] Furthermore, in step S4, the final formed convex S-shaped inlet edge profile, front and rear cover plate profiles are Bézier curves.

[0151] The blades of this invention are twisted near the front cover plate, allowing the liquid flow to receive work earlier and reducing inlet impact and vortices. To avoid the formation of low-pressure eddies and boundary layer separation within the impeller, the degree of twisting near the front cover plate at the blade inlet is increased, thereby increasing the distance between the blades at the front cover plate of the impeller. This is beneficial for improving the flow capacity for transporting impurities, thus improving efficiency.

[0152] Furthermore, when designing impellers using CF Turbo, the following steps are taken to check the diffusion between blades and the velocity variation:

[0153] Step 1: Determine whether the cross-sectional area of ​​the axial surface exhibits a perfect monotonically increasing characteristic to avoid local maximum or minimum values;

[0154] Step 2: Determine the static moment characteristic curve. The static moment values ​​at the outlets of the front and rear cover plates should be approximately equal. Using the graphical integration method, divide the line connecting the centers of the inscribed circles of the flow channel from the blade inlet to the outlet into i equal parts. Divide the length of each segment ΔS... i Multiply by the radius R from the center of the inscribed circle of the flow channel to the impeller axis. i Adding these products together gives the static moment, as shown in the following formula:

[0155] ;

[0156] In the formula: s is the static moment; ΔS i R is the length of the line connecting the centers of the i-th inscribed circle; i The radius from the center of the inscribed circle to the impeller axis;

[0157] Step 3: Determine the axial velocity to avoid areas where the local axial radius is 0;

[0158] Step 4: Determine the axial flow field characteristics;

[0159] like Figure 2As shown, the impeller designed by this invention, a multiphase flow impeller design method for centrifugal pumps used in the Yellow River basin, is a double-suction impeller with a V-shaped trailing edge design at the blade outlet. The included angle between the symmetrical blades of the impeller is 100°, i.e., the included angle between the blade and the cover plate is 130°. The double-suction impeller blades adopt a V-shaped trailing edge design at the outlet. For pumping Yellow River water containing silt, the impeller often experiences solid-liquid separation. To improve the flow conditions within the impeller, our company has developed a unique outlet velocity triangle and adopted a V-shaped trailing edge outlet structure design. Traditionally, the blades and cover plate are arranged perpendicularly. To meet the principle of large wall angles, the included angle between the symmetrical blades of this multiphase flow double-suction impeller is 100°, i.e., the included angle between the blade and the cover plate is 130°. This is also a unique feature of this impeller. This design can more rationally meet the flow conditions within the impeller under silt-containing conditions, effectively reducing losses, improving the hydraulic efficiency of the impeller, and avoiding hydraulic losses caused by impact and flow separation.

[0160] like Figure 3 As shown, the invention relates to a design method for a multiphase flow impeller in a centrifugal pump along the Yellow River basin. The impeller inlet ring is positioned where it connects to the front cover plate, and a sand discharge groove is located at the impeller cover plate before entering the sealing gap. The radius of the sand discharge groove's annular surface is [missing information]. When a medium containing solid particles enters the sand discharge tank, the velocity of the solid particles decreases, the centrifugal force decreases, and stratification occurs, eventually throwing the solid particles out to achieve the purpose of sand discharge. This prevents solid particles from entering the sealing ring and fundamentally solves the problem of impeller sealing ring wear.

[0161] Example 1:

[0162] The hydraulic parameters required for the multiphase flow impeller design task of the S1 watershed project are as follows: flow rate Q = 2.7 m³ / s. 3 / s(9720 m 3 / h), head H=64 m, speed n=740 r / min, required net positive suction head NPSHr=5.2 m.

[0163] S2. Calculate the axial flow channel size range using the velocity coefficient method based on the hydraulic parameter requirements of the design task determined in step S1.

[0164] S2.1. Calculate the specific speed n s ,

[0165] ;

[0166] S2.2. Calculation efficiency η,

[0167] Hydraulic efficiency: ;

[0168] Volumetric efficiency:

[0169] Mechanical efficiency:

[0170] efficiency: ;

[0171] S2.3. Calculate the shaft power Pa.

[0172] ;

[0173] S2.4. Calculate the power Pn.

[0174] ;

[0175] S2.5. Calculate the torque Mn.

[0176] ;

[0177] S2.6. Calculate the minimum shaft diameter d min ,

[0178] ;

[0179] The shaft adopts an enlarged shaft diameter design, with d being used. min =140mm;

[0180] S2.7. Calculate the equivalent inlet diameter D0, K0 is taken as 4.4;

[0181] ;

[0182] S2.8. Calculate the impeller outer diameter D2.

[0183] ;

[0184]

[0185] Final decision ;

[0186] S2.9. Calculate the outlet width b2.

[0187] ;

[0188] ;

[0189] The final single-suction impeller has a b2=112mm diameter, and the double-suction impeller has an outlet width of b2=224mm.

[0190] S2.10. Calculate the impeller inlet diameter D j ,

[0191] Hub diameter d h The calculation formula is:

[0192] ;

[0193] d i Shaft diameter at the impeller mounting location:

[0194] ,Pick ;

[0195] ;

[0196] Final decision ;

[0197] S2.11. Calculate the blade exit angle β2.

[0198] ;

[0199] Pick ;

[0200] Based on the above calculations, the dimensions of the double-suction impeller are determined as follows:

[0201] D2=Φ975mm; b2=224mm; D j =Φ540mm; d h =Φ245mm; β2=23°; Number of blades z=7;

[0202] S3. Based on the axial flow channel size range calculated in step S2, design the axial profile and blade spatial profile.

[0203] S3.1. In the CF Turbo software, input the single-suction impeller flow rate, head, speed, density, inlet pre-swirl state, and rotation direction, then click "OK" to proceed to the next step. Figure 4 As shown;

[0204] S3.2. Input dimensionless parameters, hydraulic efficiency, mechanical efficiency, and volumetric efficiency; CF Turbo software generates the initial main structural parameters of the impeller: minimum shaft diameter, hub diameter, inlet diameter, impeller outer diameter, and outlet width; dimensionless parameters include Intake number, Work coefficient, and Outlet width ratio; Maindimensions are the initial main structural parameters of the impeller generated by CF Turbo software; Min. Shaft diameter is the minimum shaft diameter, Hub diameter is the hub diameter, Suction diameter is the inlet diameter, Impeller diameter is the impeller outer diameter, and Outlet width is the outlet width;

[0205] S3.3. Design axial profile: Front cover, rear cover, and protruding inlet edge. The inlet edge profile is controlled by the intersection points of the inlet edge profile with the front cover profile, the intersection points of the inlet edge with the flow channel centerline, and the intersection points of the inlet edge profile with the rear cover profile. The coordinate values ​​of the three control points can be changed by right-clicking on the control points, or the position and shape of the front and rear cover profiles, inlet edge, and outlet edge can be changed by dragging the control points with the mouse. Figure 4 As shown in the figure, the points represented by the square blocks are all adjustable points;

[0206] S4. Use CFD software to simulate the shaft profile and blade spatial profile of step S3. If the simulated flow rate Q, head H, efficiency η, and shaft power Pa meet the requirements of steps S1 and S2, proceed to the next step. If the simulated flow rate Q, head H, efficiency η, and shaft power Pa do not meet the requirements of steps S1 and S2, repeat step S3. The final convex S-shaped inlet edge profile, front and rear cover plate profiles are Bézier curves, such as... Figure 5 As shown;

[0207] S5. External characteristic test of the pump's hydraulic model. After processing, dynamic balance test, static pressure test and hydraulic performance test are carried out. The hydraulic performance test includes QH test, Q-η test and Q-Pa test.

[0208] When designing impellers using CF Turbo, it's essential to examine the diffusion between blades and the velocity variation. Typical impeller front and rear cover profiles are in the form of "circular arc + straight line, straight line," etc. Simply relying on circular arcs and straight lines to achieve... Figure 5 The cross-sectional area diagram shown exhibits a perfect monotonically increasing characteristic, which is virtually impossible to achieve. The cover plate profile of the multiphase non-blocking impeller in this patent is a Bézier curve, which allows for better control of the impeller's axial surface shape and flow channel area; this is the unique feature of this impeller. The process includes the following steps:

[0209] Step 1: Determine whether the cross-sectional area of ​​the axial surface exhibits a perfect monotonically increasing characteristic, avoiding local maximum or minimum values, such as... Figure 6 As shown;

[0210] Step 2: Determine the static moment characteristic curve. The static moment values ​​at the outlets of the front and rear cover plates should be approximately equal. Using the graphical integration method, divide the line connecting the centers of the inscribed circles of the flow channel from the blade inlet to the outlet into i equal parts. Divide the length of each segment ΔS... i Multiply by the radius R from the center of the inscribed circle of the flow channel to the impeller axis. i Adding these products together gives the static moment, as shown in the following formula:

[0211] ;

[0212] In the formula: s is the static moment; ΔS iR is the length of the line connecting the centers of the i-th inscribed circle; i The radius from the center of the inscribed circle to the impeller axis;

[0213] Step 3: Determine the axial velocity to avoid regions where the axial radius is 0, such as... Figure 8 As shown;

[0214] Step 4: Determine the axial flow field characteristics; the axial velocity distribution is as follows: Figure 9 As shown.

[0215] Example 2:

[0216] The method of this invention was used to modify one of the pumps at the Yanhuan Ding No. 4 Pumping Station in a certain area, such as... Figure 10 As shown, pumps #1, #2, and #5 are all supplied by Andritz. Pump #1 and #2 are connected in parallel. Pump #4 is a pump modified using the method of this invention, operating as a single unit. Pumps #1, #2, and #4 are all driven by synchronous motors. Pump #5 is a variable frequency pump, operating as a single unit, and its purpose is to regulate the flow rate of the system.

[0217] like Figure 10 As shown, during 11 consecutive days of operation, the flow of pump #2 was unstable and a flow drop occurred; the flow of pump #4 was stable and no flow drop occurred; (2) After 11 days of operation, the total water supply of pump #2 reached 2,620,512 m³. 3 The total water intake of pump #4 reached 2,938,500 m³. 3 The total water intake of pump #4 over 11 days was 317,988 m³ more than that of pump #2. 3 If we calculate based on one pump operating for 300 days a year, pump #4 has an annual water inflow of 8,673,763.636 m3 more than pump #2.

[0218] like Figure 11 As shown, pump #2 experienced large power fluctuations and abrupt changes due to flow drops; pump #4 maintained stable power without abrupt changes. Over 11 days of operation, pump #2 consumed a total of 542,188 kWh, while pump #4 consumed 603,968 kWh. During these 11 days, pump #4's power was slightly higher than pump #2's due to its higher water intake. With the same water intake, pump #2 consumed 65,823.5 kWh more electricity than pump #4 over 11 days. If each pump operates for 300 days a year, pump #4 could save up to 110,000 kWh of electricity.

[0219] like Figure 12 As shown, the calculated average energy consumption per unit flow rate of pump #2 is 0.20690 kWh / m³. 3The average energy consumption per unit flow of pump #4 is 0.20551 kWh / m³, which is 0.672% lower than that of pump #2.

[0220] After analysis, the relevant parameters of pumps #2 and #4 are summarized in Table 1:

[0221]

[0222] Table 1: Comparison of total water intake, total power consumption, and energy consumption per unit flow rate between pump #2 and pump #4.

[0223] According to the average efficiency calculation formula: The average efficiency of pumps #2 and #4 was calculated. In the formula, Q is the average flow rate over 11 days and 264 hours (m³ / h); H is the head (m); Pa is the average power over 11 days and 264 hours (kW); and γ is the specific gravity of the Yellow River water, taken as 1.1. The calculation results are shown in Table 2.

[0224]

[0225] Table 2: Comparison of average efficiency between pump #2 and pump #4.

[0226] In this second embodiment, the total water intake of pump #4 is 12.13% higher than that of pump #2, the average energy consumption per unit flow is 0.672% lower than that of pump #2, and the efficiency is 0.58% higher than that of pump #2.

[0227] In summary, pump #4 operates more stably than pump #2, with higher water output and efficiency, and lower average energy consumption per unit flow rate.

[0228] Example 3:

[0229] The method of this invention was used to modify four pumps at a secondary substation in a village. The operating parameters of pump #16 were basically the same as those of pumps #3, #5, #8, and #9. Pumps #3, #5, #8, and #9 have been operating continuously to date, and their main performance parameters were monitored and recorded. Based on the data records, their flow rate and power data were compiled, summarized, analyzed, and compared.

[0230] Based on the operating conditions of the four pumps (#, 5, 8, and 9) after the modification, the rotor operation record data of pump #5 is the data before the modification, and the data after the modification is basically consistent with that of pump #9. In addition, based on the on-site situation, the wear of the casing and casing ring of pump #8 is the most severe, and the data record is discontinuous, resulting in a large fluctuation range in flow and power. The wear of pump #9 is relatively less severe than that of pumps #3, #5, and #8. Therefore, the performance comparison analysis is finally conducted using pump #16, pump #3, and pump #9.

[0231] like Figure 14As shown, the flow rate of pump #3 was unstable and a slight flow drop occurred; the flow rates of pumps #16 and #9 were more stable than those of pump #3; if each pump operates for 300 days a year, pump #9 has an annual water inflow of 10,411,200 m³ more than pump #3. 3 Pump #9 has an annual water inflow of 14,979,600 m³ more than pump #16. 3 .

[0232] like Figure 15 As shown, the power of pump #16 fluctuates greatly during operation, while the power of pumps #9 and #3 is more stable than that of pump #16 and no sudden changes occur. Since the water flow rate of pump #9 is higher than that of pumps #3 and #16, the power of pump #9 is higher than that of pumps #3 and #16.

[0233] like Figure 16 As shown, the calculated average energy consumption per unit flow rate of pump #16 is 0.1130 kWh / m³, and the average energy consumption per unit flow rate of pump #3 is 0.1135 kWh / m³. 3 The average energy consumption per unit flow of pump #9 is 0.1098%.

[0234] Table 3 summarizes the relevant parameters of pumps #16, #3, and #9.

[0235]

[0236] Table 3: Total water intake, total power consumption, and energy consumption per unit flow rate for pumps #16, #3, and #9.

[0237] In the comparative analysis of this embodiment, the total water intake of pump #9 was 11.37% higher than that of pump #3 and 16.36% higher than that of pump #16. The average energy consumption per unit flow of pump #9 was 0.367% lower than that of pump #3 and 0.322% lower than that of pump #16. Compared to pump #3, within 3 days, pump #9's total power consumption was 8461 kWh higher, and its total water intake was 104112 m³ more. 3 If the water supply is 104112m³ 3 Pump #3 consumes 11816.7 kWh of electricity. Therefore, under the same water flow conditions, pump #3 consumes 3355.7 kWh more electricity than pump #9. This means that after three days of operation, pump #9 will save 3355.7 kWh more energy than pump #3. If we calculate based on one pump operating for 300 days a year, pump #9 could save up to 335,500 kWh of electricity.

[0238] In summary, in this third embodiment, pump #9 operates more stably than pumps #3 and #16, and its average energy consumption per unit flow is lower than that of pumps #3 and #16, demonstrating significant energy-saving effects.

Claims

1. A design method for a multiphase flow impeller for a centrifugal pump used in the Yellow River basin, characterized in that: The steps include the following: S1. Determine the hydraulic parameter requirements for the design task, including flow rate Q, head H, rotational speed n, and required net positive suction head (NPSHr); S2. Calculate the axial flow channel size range using the velocity coefficient method based on the hydraulic parameter requirements of the design task determined in step S1. S3. Based on the axial flow channel size range calculated in step S2, design the axial profile and blade spatial profile. The specific steps are as follows: S3.

1. In the CF turbo software, input the single-suction impeller flow rate, head, speed, density, inlet pre-swirl status, and rotation direction, and click "OK" to proceed to the next step; S3.

2. Input dimensionless parameters, hydraulic efficiency, mechanical efficiency, and volumetric efficiency; CF turbo software generates preliminary structural parameters for the impeller: minimum shaft diameter, hub diameter, inlet diameter, impeller outer diameter, and outlet width; S3.

3. Design the axial profile: front cover plate, rear cover plate, and protruding inlet edge. The inlet edge profile is controlled by the intersection of the inlet edge profile with the front cover plate profile, the intersection of the inlet edge with the flow channel centerline, and the intersection of the inlet edge profile with the rear cover plate profile. You can change the coordinate values ​​of the three control points by right-clicking on the control points or directly drag the control points with the mouse to change the position and shape of the front and rear cover plate profiles, inlet edge, and outlet edge. S4. Use CFD software to simulate the shaft profile and blade spatial profile of step S3. If the flow rate Q, head H, efficiency η, and shaft power Pa after simulation meet the requirements of steps S1 and S2, proceed to the next step. If the flow rate Q, head H, efficiency η, and shaft power Pa after simulation do not meet the requirements of steps S1 and S2, repeat step S3. The final convex S-shaped inlet edge profile, front and rear cover plate profiles are Bézier curves. S5. External characteristic test of the pump's hydraulic model. After the model is manufactured, dynamic balance test, static pressure test and hydraulic performance test are carried out. The hydraulic performance test includes QH test, Q-η test and Q-Pa test. The impeller designed in steps S1-S5 is a double-suction impeller with a V-shaped trailing edge design at the blade outlet. The included angle between the symmetrical blades of the impeller is 100°, which is equivalent to a 130° included angle between the blades and the cover plate. A sand discharge groove is provided at the junction of the impeller inlet ring and the front cover plate. The sand discharge groove is located at the impeller cover plate before entering the sealing gap, and the radius of the annular surface of the sand discharge groove is [missing information]. D j This is the impeller inlet diameter.

2. The design method for a multiphase flow impeller of a centrifugal pump used in the Yellow River Basin according to claim 1, characterized in that: Step S2 includes the following steps: S2.

1. Calculate the specific speed n s The calculation formula is: In the formula: n s Specific speed; n is rotational speed; Q is flow rate; H is head; S2.

2. Calculate the efficiency η, the calculation formula is: ； In the formula: η is the efficiency; η h For hydraulic efficiency; η v For volumetric efficiency; η m For mechanical efficiency; Hydraulic efficiency η h The calculation formula is: ； Volumetric efficiency η v The calculation formula is: ； Mechanical efficiency η m The calculation formula is: ； S2.

3. Calculate the shaft power Pa using the following formula: ； In the formula: Pa is shaft power; Q is flow rate; H is head; η is efficiency; S2.

4. Calculate the power Pn, using the following formula: ； In the formula: Pn is the power of the belt; Pa is the shaft power; S2.

5. Calculate the torque Mn using the following formula: ； In the formula: Mn is torque; Pn is power output; n is rotational speed; S2.

6. Calculate the minimum shaft diameter d min The calculation formula is: ； In the formula: d min Mn is the minimum shaft diameter; Mn is the torque. The allowable stress of the material; S2.

7. Calculate the inlet equivalent diameter D0 using the following formula: ； In the formula: D0 is the equivalent inlet diameter; Q is the flow rate; n is the rotational speed; K0 is the coefficient; S2.

8. Calculate the impeller outer diameter D2 using the following formula: ； In the formula: KD2 is a coefficient; Q is the flow rate; n is the rotational speed; ;n s Specific speed; S2.

9. Calculate the outlet width b2 using the following formula: ; In the formula: b2 is the outlet width; Q is the flow rate; n is the rotational speed; ;n s Specific speed; S2.

10. Calculate the impeller inlet diameter D j The calculation formula is: ； In the formula: D j D0 is the impeller inlet diameter; D0 is the equivalent inlet diameter; d h The diameter of the wheel hub; d h The calculation formula is: ； In the formula: d i The shaft diameter at the impeller mounting location. ; S2.

11. Calculate the blade exit angle β2 using the following formula: ； In the formula: n s Specific speed.

3. The design method for a multiphase flow impeller of a centrifugal pump used in the Yellow River basin according to claim 2, characterized in that: In step S2.7, the value range of K0 is as follows: when efficiency is the main consideration, K0 = 3.5~4.0; when efficiency and cavitation are taken into account, K0 = 4.0~4.5; when cavitation is the main consideration, K0 = 4.5~5.

5.

4. The design method for a multiphase flow impeller of a centrifugal pump used in the Yellow River Basin according to claim 3, characterized in that: When designing impellers using CF Turbo, the following steps are involved in checking the diffusion between blades and the velocity variation: Step 1: Determine whether the cross-sectional area of ​​the axial surface exhibits a perfect monotonically increasing characteristic to avoid local maximum or minimum values; Step 2: Determine the static moment characteristic curve. The static moment values ​​at the outlets of the front and rear cover plates should be approximately equal. Using the graphical integration method, divide the line connecting the centers of the inscribed circles of the flow channel from the blade inlet to the outlet into i equal parts. Divide the length of each segment ΔS... i Multiply by the radius R from the center of the inscribed circle of the flow channel to the impeller axis. i Adding these products together gives the static moment, as shown in the following formula: ； In the formula: s is the static moment; ΔS i R is the length of the line connecting the centers of the i-th inscribed circle; i The radius from the center of the inscribed circle to the impeller axis; Step 3: Determine the axial velocity to avoid areas where the local axial radius is 0; Step 4: Determine the characteristics of the axial flow field.

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