A design method of high-efficiency large electric pump hydraulic model

Abstract

The application discloses a high-efficiency large electric pump hydraulic model design method, which comprises the following steps: determining the design hydraulic performance indexes such as lift, efficiency, shaft power and flow rate; adopting two one-dimensional quadratic line equations to constrain the flow channel and the blade main line; selecting a blade leading edge characteristic area to realize the parameterization control of the edge modification by using a one-dimensional quadratic parabolic equation; constructing a three-dimensional model of the flow part; completing the numerical simulation of all working conditions by calculating fluid dynamics; comparing the theoretical performance obtained through simulation with the design indexes; and iteratively adjusting the equation parameters until the deviation converges, thereby completing the model finalization. The method integrates all the key lines into a one-dimensional quadratic equation control system, relies on the characteristic of the monotonous and smooth curvature, avoids the implicit inflection point and ripple defects of high-order splines, reduces the hydraulic loss of boundary layer separation and vortex from the root, and takes the equation coefficients as the core control variables to greatly reduce the optimization dimension, so that the geometric shape is adjustable and reproducible, and the blindness and randomness of the traditional experience modification are avoided.

Description

Technical Field

[0001] This invention relates to the field of water pump design technology, and in particular to a method for designing a hydraulic model of a high-efficiency large electric pump. Background Technology

[0002] Large electric pumps, as typical high-flow-rate fluid transport machinery, are widely used in modern water conservancy and irrigation, urban flood control and water supply systems, and large-scale industrial circulating water systems. Traditional hydraulic model design for large electric pumps often relies on one-dimensional or two-dimensional simplified fluid dynamics theory and empirical coefficient methods. While the development of digital design has introduced three-dimensional CAD modeling technology, it often requires extensive empirical fine-tuning and lacks precise mathematical equation control for key geometric profiles. This results in the control curves of large electric pump blades and flow channel boundaries typically being directly connected by spline curves from discrete points, lacking globally parameterized mathematical control equations. Consequently, the designed hydraulic models of large electric pumps cannot maintain consistently high efficiency across a wide range of operating conditions. Furthermore, the lack of precise profile equation constraints (especially for the critical blade profiles and the edge of the blade inlet head) makes large electric pumps prone to geometric errors during actual manufacturing, leading to performance instability, water flow impact losses, cavitation, long design cycles, and poor repeatability. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of the prior art by providing a highly efficient hydraulic model design method for large electric pumps.

[0004] The objective of this invention is achieved through the following technical solution: a high-efficiency hydraulic model design method for large-scale electric pumps, comprising the following steps:

[0005] Step 1: Determine the design hydraulic performance indicators; the hydraulic performance indicators should include at least the design head, design efficiency, design shaft power, and design flow rate. Step 2: Parametric design of the main profile of the flow channel and blade control boundary: Two independent but coordinated univariate quadratic profile equations are used to construct the first main profile control boundary and the second main profile control boundary, which together constrain the main profile direction of the flow channel or blade. Step 3: Parametric design of airfoil trimming at the leading edge of the blade: Select the area at the leading edge of the blade, which accounts for a preset proportion of its total length, as the leading edge feature control area. Use a quadratic parabolic equation to construct the leading edge trimming control line of the blade and perform parametric control of the smooth arc edge of the blade inlet head. Step 4: Construction of 3D Hydraulic Model and Numerical Simulation Verification: Based on the main profile control boundary generated in Step 2 and the blade leading edge trimming control line generated in Step 3, a 3D model of the pump flow components is created; computational fluid dynamics is used to perform full-condition numerical simulation of the 3D model of the pump flow components, and theoretical hydraulic performance indicators are calculated, including theoretical head, theoretical efficiency, and theoretical shaft power. Step 5: Compare the theoretical hydraulic performance indicators with the design hydraulic performance indicators and output the deviation results. Adjust the parameters of the main profile control boundary and the blade leading edge trimming control line according to the deviation comparison results. Repeat steps 4 and 5 until the deviation results converge to the preset deviation range, thereby completing the three-dimensional model of the electric pump flow components.

[0006] Preferably, the leading edge trimming control line of the blade is smooth and continuous with the trailing profile curve of the blade.

[0007] Preferably, in step three, the preset ratio ranges from 13% to 15%.

[0008] Preferably, in step two, the equation for the first main profile control boundary is: ; In the formula, These are the coefficients of the first and second quadratic terms, used to dominate the flow channel curvature at the control boundary of the first principal profile. The coefficient of the first linear term is used to constrain the tangent slope of the initial segment of the first main profile control boundary in order to control the inlet placement trend of the flow channel; The coefficient of the first constant term; The equation for the control boundary of the second principal curve is: ; In the formula, The coefficient of the second quadratic term is used to control the diffusion rate of the second principal curve control boundary and the pressure gradient change in the flow channel; The coefficient for the second-order term is used to control the geometric discharge tendency of the outlet section of the flow channel; This is the coefficient of the second constant term.

[0009] Preferably, in step three, the equation for the blade leading edge trimming control line is: ; In the formula, The coefficient for the third quadratic term is used to control the radius of curvature at the tip of the blade's leading edge. The coefficient of the third-order term is used to control the tangent slope at the tip of the blade's leading edge. This is the coefficient of the third constant term.

[0010] Preferably, in step four, the total hydrodynamic torque T on the impeller is extracted through full-condition numerical simulation. and The average total pressure of the outlet cross-section is respectively Average total pressure of the inlet cross-section , The formula for calculating the theoretical head H is: ; In the formula, Where is the density of the fluid medium, and g is the acceleration due to gravity; The formula for calculating shaft power P is: ; In the formula, n is the rated speed of the electric pump; Theoretical efficiency The calculation formula is: ; In the formula, Q represents the design flow rate.

[0011] As a preferred option, in step five, when adjusting the parameters of the main profile control boundary and the blade leading edge trimming control line based on the deviation comparison results, the specific method is as follows: When the theoretical head is lower than the design head, increase the coefficient of the first quadratic term a1 of the first main shape line control boundary, or adjust the coefficient of the second linear term b2 of the second main shape line control boundary. When the theoretical efficiency is lower than the design efficiency, fine-tune the coefficient b1 of the first linear term of the first main profile control boundary, or fine-tune the coefficient a2 of the second quadratic term of the second main profile control boundary. When the static pressure in the leading edge region of the blade is lower than the saturated vapor pressure at the current temperature and there is a risk of cavitation, reduce the coefficient a3 of the third quadratic term of the leading edge trimming control line, or fine-tune the coefficient b3 of the third linear term of the leading edge trimming control line.

[0012] Preferably, in step five, the coefficients a1 of the quadratic term and the coefficient of the linear term are respectively... The coefficient of the second quadratic term a2, the coefficient of the second linear term The coefficient of the quadratic term a3, the coefficient of the linear term Set the corresponding constraint range; When adjusting the above coefficients, if the relative deviation between the theoretical hydraulic performance index and the design hydraulic performance index exceeds a set deviation threshold, the step size for a single adjustment is the base step size, which is the width of the constraint interval corresponding to that coefficient. ; When the relative deviation between the theoretical hydraulic performance index and the design hydraulic performance index is less than the set deviation threshold, the step size of a single adjustment is 0.5 times the base step size.

[0013] Preferably, in step five, the constraint interval for the coefficient a1 of the first quadratic term is [-0.00523, -0.00506]. coefficient of the first linear term The constraint interval is [1.753, 1.799]. The constraint interval for the coefficient a2 of the second quadratic term is [0.00085, 0.00091]. coefficient of the second linear term The constraint interval is [-0.328, -0.312]; The constraint interval for the coefficient a3 of the third quadratic term is [1.400, 1.539]. coefficient of the third linear term The constraint interval is [-0.061, 0.061].

[0014] As a preferred option, the specific method for full-condition numerical simulation in step four is as follows: The fluid domain of the three-dimensional model of the electric pump's flow components was meshed using a fully hexahedral structured mesh, and mesh independence verification was performed. Import the meshed 3D model into the CFD solver; The boundary conditions are set as follows: pressure inlet, mass flow outlet, and no-slip wall condition for solid wall. The turbulence model selected is k ω-turbulence model.

[0015] The beneficial effects of this invention are: 1. This invention incorporates all key profiles of the flow channel body and the leading edge of the blade into a mathematical control system of a quadratic equation. The quadratic equation has the inherent mathematical characteristics of monotonic curvature and smooth change, which can eliminate the implicit inflection points and local ripple defects that are prone to occur in high-order spline curves. It eliminates the conditions for the generation of local reverse pressure gradients in the flow channel at the profile level, and reduces boundary layer separation and vortex hydraulic losses from the root. In the iterative optimization process, the equation coefficients are used as the core control variables to replace the multi-parameter adjustment of traditional discrete profile points, which greatly reduces the variable dimension of digital optimization, making the geometric shape directionally adjustable and accurately reproduced, and completely getting rid of the blindness and randomness of traditional experience-based profile modification.

[0016] 2. This invention employs a design that coordinates two main profile lines for control and optimizes the blade leading edge trimming. The equations of the two main profile lines can precisely constrain the tangent slope and placement trend of the inlet section of the flow channel, enabling a "collision-free slip" transition between the inflow streamline and the profile boundary at the design flow rate. This significantly reduces the impact loss of the inlet water flow and directly improves the hydraulic efficiency at the design operating point. For the blade leading edge, a high-risk area for cavitation, an independent one-dimensional quadratic parabola is used for smooth trimming. On the one hand, this can precisely control the radius of curvature of the leading edge, reduce the local velocity peak of the fluid flow around it, and raise the minimum static pressure at the leading edge. On the other hand, it can ensure a smooth transition between the trimmed section and the blade main profile at the junction, avoiding local low-pressure vortex areas caused by abrupt changes in curvature. This effectively suppresses primary cavitation and reduces cavitation stripping and vibration problems.

[0017] 3. This invention adopts a parametric design approach, using geometric lines precisely described by mathematical equations. This allows for direct integration with 3D CAD modeling and CNC machining equipment, avoiding fitting errors in the traditional discrete point-to-machining process. This significantly improves the manufacturing accuracy of the hydraulic model, ensuring the performance consistency between the finished product and the design model, and reducing performance instability caused by geometric deviations. The parametric 3D model supports rapid geometric reconstruction. Combined with a closed-loop iterative process of "full-condition simulation - deviation detection - parameter adjustment," performance optimization can be completed without relying on a large number of physical experiments, significantly shortening the R&D and verification cycle of the hydraulic model. Furthermore, the design results are repeatable and traceable. Attached Figure Description

[0018] Figure 1 This is a schematic diagram showing the design locations of the first and second main profile control boundaries.

[0019] Figure 2 This is a schematic diagram of the leading edge trimming control line of the blade.

[0020] Figure 3 The flow-head curves of the electric pump before and after optimization are shown.

[0021] Figure 4 The flow-shaft power curves of the electric pump before and after optimization are shown.

[0022] Figure 5 The graph shows the flow-efficiency curves of the electric pump before and after optimization. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0024] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0025] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0026] A method for designing a high-efficiency hydraulic model for a large electric pump includes the following steps: Step 1: Determine the design hydraulic performance indicators; the hydraulic performance indicators should include at least the design head, design efficiency, and design shaft power.

[0027] In this embodiment, the rated speed n of the electric pump is Design flow Design head Design efficiency Design shaft power .

[0028] Step 2: Parametric design of the main profile of the flow channel and blade control boundary: Two independent but coordinated univariate quadratic profile equations are used to construct the first main profile control boundary and the second main profile control boundary, which together constrain the main profile direction of the flow channel or blade.

[0029] In this step, high-order equations (such as cubic and higher-order spline curves) are prone to generating unnecessary implicit inflection points or minute ripples (i.e., flow separation in numerical calculations) within the curve during multi-parameter rolling optimization or coefficient fine-tuning. In high-speed flow fields, these minute curvature fluctuations can lead to the generation of adverse pressure gradients in the flow channel, thereby causing boundary layer de-flow and severe vortex hydraulic losses. In this invention, quadratic equations are used to effectively avoid flow separation. Quadratic equations have strictly monotonic and smooth curvature change characteristics, which can ensure a highly smooth acceleration or deceleration process of the fluid in the flow channel. At the same time, quadratic equations can achieve fully parameterized precise control with a minimum number of characteristic coefficients (3 parameters), greatly compressing the dimension of control variables in subsequent digital solution and multi-objective optimization, and improving the convergence speed.

[0030] like Figure 1 As shown, the two main profile control boundary curves of the large electric pump are controlled by two equations respectively.

[0031] The equation for the first principal curve control boundary is: ; In the formula, These are the coefficients of the first and second quadratic terms, used to dominate the flow channel curvature at the control boundary of the first principal profile. The coefficient of the first linear term is used to constrain the tangent slope of the initial segment of the first main profile control boundary in order to control the inlet placement trend of the flow channel; is the coefficient of the first constant term.

[0032] The constraint interval is [-0.00523, -0.00506]; The constraint interval is [1.753, 1.799]. The constraint interval is [-120.20, -117.20].

[0033] Among them, the coefficients of the first and second terms The curvature of the flow channel at the control boundary of the first main profile line. If > 0.00506, the profile flow channel curvature is too gentle, making it impossible to complete the flow channel turning within the limited axial space, resulting in an excessively large axial dimension of the pump body; if < At a value of 0.00523, the local curvature is too large. When the fluid passes through this boundary, it is very easy for local "overload and flow separation" to occur due to centrifugal force, which causes the hydraulic efficiency to drop sharply.

[0034] coefficient of the first linear term Strictly constrain the tangent slope of the initial section of the profile, corresponding to the inlet placement trend of the flow channel. Within the value range of [1.753, 1.799], it can be ensured that the design flow rate is within the acceptable range. Under this premise, the streamlines and boundaries at the inlet achieve a "collision-free slip" transition, minimizing inlet impact losses.

[0035] First constant term As an absolute spatial positioning parameter, it works together with a1 and b1 to determine the cross-sectional area of ​​the flow channel at the beginning, thus avoiding severe resistance loss caused by sudden contraction of the flow channel.

[0036] The equation for the control boundary of the second principal curve is: ; In the formula, The coefficient of the second quadratic term is used to control the diffusion rate of the second principal curve control boundary and the pressure gradient change in the flow channel; The coefficient for the second-order term is used to control the geometric discharge tendency of the outlet section of the flow channel; This is the coefficient of the second constant term.

[0037] The constraint interval is [0.00085, 0.00091]. The constraint interval is [-0.328, -0.312]. The constraint interval is [130.96, 132.01].

[0038] Among them, the coefficient of the second quadratic term The diffusion rate and pressure gradient within the channel are controlled by the second main profile control boundary. Its value is strictly limited to [0.00085, 0.00091] to coordinate with the first main profile control boundary, ensuring a gradual change in the cross-sectional area of ​​the flow channel formed by the combination of the two profiles. Exceeding this range will lead to excessively rapid diffusion in localized areas of the flow channel, preventing the smooth conversion of kinetic energy into pressure energy, and consequently inducing severe secondary flow and wake losses.

[0039] coefficient of the second linear term This determines the geometric discharge tendency of the outlet section of the flow channel. Within this range, it ensures good axial balance of the effluent flow, suppresses the loss of residual kinetic energy from the outlet rotation, and achieves optimal rectification effect in conjunction with the guide vanes.

[0040] Second constant term Used to accurately locate the radial and axial relative distances between the second main profile control boundary and the first main profile control boundary, and to establish the most reasonable flow capacity of the blade channel space.

[0041] Step 3: Parametric design of the leading edge airfoil trimming of the blade tip: Select the area at the blade tip that accounts for a preset proportion of its total length as the leading edge feature control area, and use a univariate quadratic parabolic equation to construct the blade leading edge trimming control line to perform parametric control of the smooth arc edge of the blade inlet tip.

[0042] The preset ratio ranges from 13% to 15%, meaning that the section of the blade tip with a length of 13% to 15% is designated as the leading edge feature control zone.

[0043] like Figure 2 As shown, a blade leading edge trimming control line is constructed using a quadratic parabolic equation to precisely parameterize the smooth arc-shaped edge line of the blade leading edge (water inlet head position).

[0044] Specifically, the equation for the blade leading edge trimming control line is: ; In the formula, The coefficient for the third quadratic term is used to control the radius of curvature at the tip of the blade's leading edge. The coefficient of the third-order term is used to control the tangent slope at the tip of the blade's leading edge. This is the coefficient of the third constant term.

[0045] The constraint intervals for the above coefficients are as follows: The constraint interval is [1.400, 1.539]. The constraint interval is [-0.061, 0.061]; The constraint interval is [-0.463, -0.200].

[0046] This invention abandons the traditional standard circular arc method (which is prone to curvature abrupt changes at the junction with the blade body profile) and the high-order spline curve method (which is prone to generating small implicit inflection points or ripples during multivariable rolling optimization) in the design of blade leading edge trimming, and proposes a leading edge trimming control model based on the quadratic parabola equation.

[0047] The underlying logic lies in the fact that the quadratic equation possesses a strictly monotonic and smoothly varying curvature characteristic. In fluid dynamics, the 13%-15% region at the inlet leading edge is designated as the decoupled leading-edge characteristic control zone. The quadratic equation ensures that the development of the surface velocity gradient and boundary layer thickness remains highly smooth as the fluid transitions from the leading-edge stagnation point to the blade suction and pressure surfaces, preventing local velocity surges at the flow surfaces. Furthermore, this univariate quadratic parabolic equation is controlled by only three independent characteristic coefficients, resulting in low-dimensional control variables and clear geometric boundaries, significantly improving the convergence speed during subsequent multi-objective CFD optimization under all operating conditions.

[0048] Among them, the coefficient of the third quadratic term This determines the sharpness of the blade's leading edge tip (i.e., the radius of curvature of the leading edge). If... This results in an excessively sharp blade leading edge profile, leading to excessive local centripetal acceleration and flow velocity around the leading edge. This creates an extreme velocity peak at the suction front, and according to Bernoulli's principle, the static pressure at this point will drop sharply below the fluid vaporization pressure, resulting in severe primary cavitation and cavitation erosion. If the leading edge profile is too blunt and rounded, it will significantly increase the squeezing effect at the blade inlet (excessive squeezing coefficient) and expand the stagnation impact zone, causing violent impacts of the inflow at the blade tip and inducing local flow separation and vortices. This will also cause the low pressure at the vortex core to induce high-frequency vibrations and cavitation. Therefore, [the following is a continuation of the previous sentence, but the context is unclear: "…"] Strictly limited to the range of [1.400, 1.539], the leading edge curvature radius and the fluid velocity can be optimally matched, effectively suppressing the overspeed peak of the suction surface and increasing the local extreme static pressure.

[0049] coefficient of the third linear term The slope of the tangent at the tip of the leading edge is used to control the offset angle of the blade profile relative to the blade inlet placement angle (geometric axis). Within the constraint range of [-0.061, 0.061], it ensures that the design flow rate is within acceptable limits. Within the entire operating condition flow fluctuation range, the geometric center trend of the leading edge profile remains highly consistent with the relative velocity vector (flow angle) of the inflow, achieving a "non-impact slip" transition. Beyond this range, the leading edge profile will generate an excessively large positive or negative angle of attack with the incoming flow, resulting in severe boundary layer separation and unstable shedding vortices at the root of the suction or pressure surface. The extremely low-pressure area at the center of the shedding vortex not only causes a precipitous drop in pump efficiency but is also the main cause of cavitation during full-condition operation.

[0050] constant term As parameters for absolute spatial positioning and geometric connection, it strictly constrains the thickness gradient and spatial displacement of the leading edge airfoil from the tip apex to the characteristic endpoint of the first 13%-15% of the tip. Its core function is to ensure that the leading edge trimming section and the mid-to-rear section airfoil of the blade body, controlled by the first principal airfoil control boundary and the second principal airfoil control boundary in step two, achieve a smooth continuity of the first derivative (slope) and the second derivative (curvature) at the docking point. Exceeding this range can lead to geometric steps, abrupt curvature changes, or sudden contractions in the blade profile at the junction of the leading edge trim and the main profile of the middle section. Fluid flowing through this transition boundary will generate a local adverse pressure gradient, inducing premature boundary layer separation and severe hydrostatic oscillations and subsidence. Therefore, this range limit ensures a smooth transition of the entire flow channel profile, eliminating the potential for localized pressure drops and cavitation caused by geometric discontinuities.

[0051] Step 4: Construction of 3D Hydraulic Model and Numerical Simulation Verification: Based on the main profile control boundary generated in Step 2 and the blade leading edge trimming control line generated in Step 3, a 3D model of the pump flow components is created; computational fluid dynamics is used to perform full-condition numerical simulation of the 3D model of the pump flow components, and theoretical hydraulic performance indicators are calculated, including theoretical head, theoretical efficiency, and theoretical shaft power.

[0052] In this step, the parametric geometric control lines (i.e., leading edge trimming control lines, first main profile control boundary, and second main profile control boundary) obtained in steps two and three are imported into three-dimensional reverse engineering or CAD modeling software. A three-dimensional solid model of the overall flow-through components of the large electric pump (including impeller blades, guide vanes, suction chamber, and discharge chamber) is established through curve lofting and surface stitching techniques.

[0053] The full-condition numerical simulation was achieved using computational fluid dynamics (CFD), specifically as follows: The fluid domain of the three-dimensional model of the electric pump's flow components was meshed using a fully hexahedral structured mesh, and mesh independence verification was performed. Import the meshed 3D model into the CFD solver; The boundary conditions are set as follows: pressure inlet, mass flow outlet, and no-slip wall condition for solid wall. The turbulence model selected is k ω-turbulence model.

[0054] The total hydrodynamic torque T on the impeller was extracted through full-condition numerical simulation. and The average total pressure of the outlet cross-section is respectively Average total pressure of the inlet cross-section , and The unit for all values ​​is Pascal (Pa).

[0055] The formula for calculating the theoretical head H is as follows: ; In the formula, The density of the fluid medium is expressed in units of ( ). g is the acceleration due to gravity, with units of (m / s²). ); The formula for calculating shaft power P is: ; In the formula, n is the rated speed of the electric pump; Theoretical efficiency The calculation formula is: ; In the formula, Q represents the design flow rate.

[0056] Step 5: Compare the theoretical hydraulic performance indicators with the design hydraulic performance indicators and output the deviation results. Adjust the parameters of the main profile control boundary and the blade leading edge trimming control line according to the deviation comparison results. Repeat steps 4 and 5 until the deviation results converge to the preset deviation range, thereby completing the three-dimensional model of the electric pump flow components.

[0057] Specifically, when adjusting the parameters of the main profile control boundary and the blade leading edge trimming control line based on the deviation comparison results, the specific method is as follows: When the theoretical head is lower than the design head, increase the coefficient a1 of the first quadratic term of the first main curve control boundary, or adjust the coefficient b of the second linear term of the second main curve control boundary. 2。 The adjustment is based on the following principle: appropriately increasing the quadratic term coefficient in the control boundary of the first main profile within a defined range. (Increase the overall axial curvature of the flow channel to enhance the work done by fluid diversion; or adjust the coefficient of the first-order term in the control boundary of the second principal profile) This is to optimize the outlet discharge trend and suppress the loss of residual kinetic energy from the outlet rotation.

[0058] When the theoretical efficiency is lower than the design efficiency, fine-tune the coefficient b1 of the first linear term of the first principal shape line control boundary, or fine-tune the coefficient a of the second quadratic term of the second principal shape line control boundary. 2。 The adjustment is based on the following: the decrease in efficiency indicates unnecessary impact losses in the flow channel of the electric pump or boundary layer desorption caused by uneven curvature; the linear coefficient of the first principal profile is controlled by fine-tuning the first term coefficient of the boundary. This allows for a better "impact-free slip" match between the tangent slope of the initial section of the profile and the flow angle at the inlet design flow rate, reducing inlet impact. If there is an overload risk at low flow rates, the quadratic coefficient of the second master profile control boundary can be finely adjusted. The cross-sectional area of ​​the flow channel formed by the combination of the two profiles is gradually changed to suppress secondary flow and wake loss.

[0059] When the static pressure in the leading edge region of the blade is lower than the saturated vapor pressure at the current temperature and there is a risk of cavitation, reduce the coefficient of the third quadratic term a3 of the leading edge trimming control line, or fine-tune the coefficient of the third linear term b3 of the leading edge trimming control line. The rationale for this adjustment is: when the static pressure in the leading edge region of the blade is lower than the saturated vapor pressure at the current temperature, it indicates that the flow velocity around the leading edge of the blade is too high, causing a decrease in static pressure. Appropriately reducing the quadratic term coefficient of the leading edge trimming control line is beneficial. This makes the leading edge profile of the blade relatively smooth, reducing the peak velocity on the flow surface; at the same time, it fine-tunes the first-order term coefficient of the leading edge trimming control line of the blade. This eliminates edge shedding vortices and local extreme low-pressure areas caused by positive / negative angles of attack under full-condition fluctuations.

[0060] As mentioned above, the constraint interval for the coefficient a1 of the first quadratic term is [-0.00523, -0.00506]; coefficient of the first linear term The constraint interval is [1.753, 1.799]. The constraint interval for the coefficient a2 of the second quadratic term is [0.00085, 0.00091]. coefficient of the second linear term The constraint interval is [-0.328, -0.312]; The constraint interval for the coefficient a3 of the third quadratic term is [1.400, 1.539]. coefficient of the third linear term The constraint interval is [-0.061, 0.061].

[0061] When adjusting the above coefficients, if the relative deviation between the theoretical hydraulic performance index and the design hydraulic performance index exceeds a set deviation threshold, the step size for a single adjustment is the base step size, which is the width of the constraint interval corresponding to that coefficient. When the relative deviation between the theoretical hydraulic performance index and the design hydraulic performance index is less than the set deviation threshold, the step size of a single adjustment is 0.5 times the base step size.

[0062] During the iterative optimization process, if the relative error between the theoretical hydraulic performance index and the design hydraulic performance index is reduced to within the set deviation threshold (e.g., 2%), the single adjustment step size is automatically reduced to 0.5 times the base step size, and the process enters the fine-tuning stage.

[0063] like Figure 3-5 As shown, after the design optimization of this invention, compared with the traditional design method (before optimization), the shaft power is reduced under the same flow conditions, thereby achieving energy saving and improving efficiency.

[0064] Compared with existing technologies, the present invention has the following advantages: 1. This invention incorporates all key profiles of the flow channel body and the leading edge of the blade into a mathematical control system of a quadratic equation. The quadratic equation has the inherent mathematical characteristics of monotonic curvature and smooth change, which can eliminate the implicit inflection points and local ripple defects that are prone to occur in high-order spline curves. It eliminates the conditions for the generation of local reverse pressure gradients in the flow channel at the profile level, and reduces boundary layer separation and vortex hydraulic losses from the root. In the iterative optimization process, the equation coefficients are used as the core control variables to replace the multi-parameter adjustment of traditional discrete profile points, which greatly reduces the variable dimension of digital optimization, making the geometric shape directionally adjustable and accurately reproduced, and completely getting rid of the blindness and randomness of traditional experience-based profile modification.

[0065] 2. This invention employs a design that coordinates two main profile lines for control and optimizes the blade leading edge trimming. The equations of the two main profile lines can precisely constrain the tangent slope and placement trend of the inlet section of the flow channel, enabling a "collision-free slip" transition between the inflow streamline and the profile boundary at the design flow rate. This significantly reduces the impact loss of the inlet water flow and directly improves the hydraulic efficiency at the design operating point. For the blade leading edge, a high-risk area for cavitation, an independent one-dimensional quadratic parabola is used for smooth trimming. On the one hand, this can precisely control the radius of curvature of the leading edge, reduce the local velocity peak of the fluid flow around it, and raise the minimum static pressure at the leading edge. On the other hand, it can ensure a smooth transition between the trimmed section and the blade main profile at the junction, avoiding local low-pressure vortex areas caused by abrupt changes in curvature. This effectively suppresses primary cavitation and reduces cavitation stripping and vibration problems.

[0066] 3. This invention adopts a parametric design approach, using geometric lines precisely described by mathematical equations. This allows for direct integration with 3D CAD modeling and CNC machining equipment, avoiding fitting errors in the traditional discrete point-to-machining process. This significantly improves the manufacturing accuracy of the hydraulic model, ensuring the performance consistency between the finished product and the design model, and reducing performance instability caused by geometric deviations. The parametric 3D model supports rapid geometric reconstruction. Combined with a closed-loop iterative process of "full-condition simulation - deviation detection - parameter adjustment," performance optimization can be completed without relying on a large number of physical experiments, significantly shortening the R&D and verification cycle of the hydraulic model. Furthermore, the design results are repeatable and traceable.

[0067] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for designing a high-efficiency hydraulic model for a large-scale electric pump, characterized in that, Includes the following steps: Step 1: Determine the design hydraulic performance indicators; the hydraulic performance indicators should include at least the design head, design efficiency, design shaft power, and design flow rate. Step 2: Parametric design of the main profile of the flow channel and blade control boundary: Two independent but coordinated univariate quadratic profile equations are used to construct the first main profile control boundary and the second main profile control boundary, which together constrain the main profile direction of the flow channel or blade. Step 3: Parametric design of airfoil trimming at the leading edge of the blade: Select the area at the leading edge of the blade, which accounts for a preset proportion of its total length, as the leading edge feature control area. Use a quadratic parabolic equation to construct the leading edge trimming control line of the blade and perform parametric control of the smooth arc edge of the blade inlet head. Step 4: Construction of 3D Hydraulic Model and Numerical Simulation Verification: Based on the main profile control boundary generated in Step 2 and the blade leading edge trimming control line generated in Step 3, a 3D model of the pump flow components is created; computational fluid dynamics is used to perform full-condition numerical simulation of the 3D model of the pump flow components, and theoretical hydraulic performance indicators are calculated, including theoretical head, theoretical efficiency, and theoretical shaft power. Step 5: Compare the theoretical hydraulic performance indicators with the design hydraulic performance indicators and output the deviation results. Adjust the parameters of the main profile control boundary and the blade leading edge trimming control line according to the deviation comparison results. Repeat steps 4 and 5 until the deviation results converge to the preset deviation range, thereby completing the three-dimensional model of the electric pump flow components.

2. The high-efficiency large-scale electric pump hydraulic model design method according to claim 1, characterized in that, In step three, the preset ratio ranges from 13% to 15%.

3. The high-efficiency large-scale electric pump hydraulic model design method according to claim 1, characterized in that, In step two, the equation for the first principal curve control boundary is: ； In the formula, These are the coefficients of the first and second quadratic terms, used to dominate the flow channel curvature at the control boundary of the first principal profile. The coefficient of the first linear term is used to constrain the tangent slope of the initial segment of the first main profile control boundary in order to control the inlet placement trend of the flow channel; The coefficient of the first constant term; The equation for the control boundary of the second principal curve is: ； In the formula, The coefficient of the second quadratic term is used to control the diffusion rate of the second principal curve control boundary and the pressure gradient change in the flow channel; The coefficient for the second-order term is used to control the geometric discharge tendency of the outlet section of the flow channel; This is the coefficient of the second constant term.

4. The high-efficiency large-scale electric pump hydraulic model design method according to claim 3, characterized in that, In step three, the equation for the blade leading edge trimming control line is: ； In the formula, The coefficient for the third quadratic term is used to control the radius of curvature at the tip of the blade's leading edge. The coefficient of the third-order term is used to control the tangent slope at the tip of the blade's leading edge. This is the coefficient of the third constant term.

5. The high-efficiency large-scale electric pump hydraulic model design method according to claim 1, characterized in that, In step four, the total hydrodynamic torque T on the impeller is extracted through full-condition numerical simulation. and The average total pressure of the outlet cross-section is respectively Average total pressure of the inlet cross-section , The formula for calculating the theoretical head H is: ; In the formula, Where is the density of the fluid medium, and g is the acceleration due to gravity; The formula for calculating shaft power P is: ； In the formula, n is the rated speed of the electric pump; Theoretical efficiency The calculation formula is: ； In the formula, Q represents the design flow rate.

6. The high-efficiency large-scale electric pump hydraulic model design method according to claim 4, characterized in that, In step five, when adjusting the parameters of the main profile control boundary and the blade leading edge trimming control line based on the deviation comparison results, the specific method is as follows: When the theoretical head is lower than the design head, increase the coefficient of the first quadratic term a1 of the first main shape line control boundary, or adjust the coefficient of the second linear term b2 of the second main shape line control boundary. When the theoretical efficiency is lower than the design efficiency, fine-tune the coefficient b1 of the first linear term of the first main profile control boundary, or fine-tune the coefficient a2 of the second quadratic term of the second main profile control boundary. When the static pressure in the leading edge region of the blade is lower than the saturated vapor pressure at the current temperature and there is a risk of cavitation, reduce the coefficient a3 of the third quadratic term of the leading edge trimming control line, or fine-tune the coefficient b3 of the third linear term of the leading edge trimming control line.

7. The high-efficiency large-scale electric pump hydraulic model design method according to claim 6, characterized in that, In step five, the coefficients a1 of the quadratic term and the coefficient of the linear term are respectively... The coefficient of the second quadratic term a2, the coefficient of the second linear term The coefficient of the quadratic term a3, the coefficient of the linear term Set the corresponding constraint range; When adjusting the above coefficients, if the relative deviation between the theoretical hydraulic performance index and the design hydraulic performance index exceeds a set deviation threshold, the step size for a single adjustment is the base step size, which is the width of the constraint interval corresponding to that coefficient. ; When the relative deviation between the theoretical hydraulic performance index and the design hydraulic performance index is less than the set deviation threshold, the step size of a single adjustment is 0.5 times the base step size.

8. The high-efficiency large-scale electric pump hydraulic model design method according to claim 7, characterized in that, In step five, the constraint interval for the coefficient a1 of the first quadratic term is [-0.00523, -0.00506]. coefficient of the first linear term The constraint interval is [1.753, 1.799]. The constraint interval for the coefficient a2 of the second quadratic term is [0.00085, 0.00091]. coefficient of the second linear term The constraint interval is [-0.328, -0.312]; The constraint interval for the coefficient a3 of the third quadratic term is [1.400, 1.539]. coefficient of the third linear term The constraint interval is [-0.061, 0.061].

9. The high-efficiency large-scale electric pump hydraulic model design method according to claim 1, characterized in that, In step four, the specific method for full-condition numerical simulation is as follows: The fluid domain of the three-dimensional model of the electric pump's flow components was meshed using a fully hexahedral structured mesh, and mesh independence verification was performed. Import the meshed 3D model into the CFD solver; The boundary conditions are set as follows: pressure inlet, mass flow outlet, and no-slip wall condition for solid wall. The turbulence model selected is k ω-turbulence model.

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