CN111737831B - Method for establishing parameter system of centrifugal pump impeller - Google Patents
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Abstract
The invention discloses a method for establishing a parameter system of a centrifugal pump impeller in the technical field of centrifugal pump impellers, which aims to solve the technical problems of more parameter system variables, low operation efficiency of an optimization algorithm and poor system robustness of the centrifugal pump impeller in the prior art, and comprises the following steps: establishing a parameter system in a hierarchical structure; establishing a cooperative connection relation for a parameter system; establishing a general constraint relation for a parameter system; and adding auxiliary constraint to the parameter system according to the optimization problem. According to the invention, by constructing a parameter system with a framework hierarchy structure, each geometrical characteristic and the corresponding free parameter belong to a specific hierarchy; the dimension and the range of a parameter space can be reduced by establishing a cooperative connection relation and a constraint relation for the parameter system, and the working efficiency of the optimization system is exponentially improved; and secondly, most unreasonable combination parameter combinations can be eliminated, so that a feedback mechanism of the optimization system can stably operate, and the robustness of the optimization system and the operation efficiency of the system are improved.
Description
Technical Field
The invention belongs to the technical field of centrifugal pump impellers, and particularly relates to a parameter system establishment method of a centrifugal pump impeller.
Background
Impeller machines such as turbines, water turbines, vane pumps, air compressors, fans and the like are widely used power conversion equipment in the fields of agriculture, industry and the like, and play an important role in the development of national economy and the improvement of living standard.
Among vane pumps, centrifugal pumps in particular are most widely used. Is indispensable in the industries of chemical industry, construction, ferrous metallurgy, municipal administration, building water supply and drainage, heat supply, agriculture, hydraulic engineering, fire fighting and the like. Although used for a long time in various industries, there are still many works to be developed in view of the existing development level of the water pump. For example, the characteristic features of the excellent hydraulic model are researched, and the efficiency, the running stability, the service life and the like of the existing model are improved. Most of these problems can be solved by building a mathematical model with the idea of optimizing the problem.
The existing centrifugal pump parameterization system is mostly defined in a geometric dimension mode, the system is mainly established by the requirement of three-dimensional modeling, but for the optimization problem, the system has low operation efficiency and even fails of an optimization algorithm due to the large number of variables. Furthermore, because of the ambiguous constraint relationships between parameters, a large range of meaningless regions appear in the optimization space, which may directly lead to a breakdown of the solution process of the optimization problem.
Disclosure of Invention
The invention aims to provide a method for establishing a parameter system of a centrifugal pump impeller, which aims to solve the technical problems of more parameter system variables, low operation efficiency of an optimization algorithm and poor system robustness of the centrifugal pump impeller in the prior art.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: a parameter system establishment method of a centrifugal pump impeller comprises the following steps: establishing a parameter system in a hierarchical structure; establishing a cooperative connection relation for a parameter system; establishing a general constraint relation for a parameter system; and adding auxiliary constraint to the parameter system according to the optimization problem.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the invention, by constructing a parameter system with a framework hierarchy structure, each geometrical characteristic and the corresponding free parameter belong to a specific hierarchy; this allows the subsequent optimization system to take place in a branched structure when dealing with both continuous and discrete variables; the architecture design of the optimization system is greatly facilitated;
(2) The invention establishes a cooperative connection relation and a constraint relation for the parameter system, so that the dimension and the range of a parameter space can be reduced, and the working efficiency of an optimization system can be exponentially improved; secondly, most unreasonable combination parameter combinations can be removed, so that a feedback mechanism of the optimization system can be ensured to run stably, and the robustness of the optimization system is improved;
(3) By using a parameter system with a framework hierarchy, iterative processing steps can be used when exploring a parameter space; thereby reducing the time consumed by the optimizing system to complete a task; the operation efficiency of the system is improved.
Drawings
FIG. 1 is a summary of a parameter system according to the present invention;
FIG. 2 is a parameterized schematic view of a back cover plate profile whose geometric topology is defined as a four-time Bezier curve with five control points for a total of 10 independent parameters;
FIG. 3 is a parameterized schematic view of a front cover plate profile whose geometric topology is defined as a four-time Bezier curve with five control points for a total of 10 independent parameters;
FIG. 4 is a parameterized schematic view of an inlet edge profile whose geometric topology is defined as a four-time Bezier curve with five control points for a total of 10 independent parameters;
FIG. 5 is a wrap angle control curve on the front cover flow surface, with the abscissa being the dimensionless meridian flow length (current location meridian flow length divided by total length), for a total of 8 independent parameters;
FIG. 6 is a wrap angle control curve on the intermediate flow surface, with the abscissa being the dimensionless meridian surface streamline length (current location meridian surface streamline length divided by total length), for a total of 8 independent parameters;
FIG. 7 is a wrap angle control curve on the back cover flow surface, with the abscissa being the dimensionless meridian flow length (current location meridian flow length divided by total length), for a total of 8 independent parameters;
FIG. 8 is a graph showing the variation of blade thickness with flow direction position on the flow surface of the front cover plate and the rear cover plate, with the abscissa being the meridian surface streamline length of the blade (meridian surface streamline length of the current blade position divided by the total length) without tempering, for a total of 13 independent parameters;
fig. 9 is a flow chart of a method for establishing a parameter system of a centrifugal pump impeller according to an embodiment of the invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present invention, and are not intended to limit the scope of the present invention.
Embodiment one:
as shown in fig. 1 to 9, taking a centrifugal pump design as an example, the pump design parameters are shown in table 1:
table 1 centrifugal pump design parameter table
| Parameters (parameters) | Value of | Unit (B) |
| Flow rate | 0.998 | m 3 /s |
| Lifting head | 3.583 | m |
| Rotational speed | 5621 | rpm |
| Density of | 1000 | kg/m 3 |
The design requirement is that the diameter of the impeller is within 30mm, the lift cannot be lower than 3.583m, and the efficiency is as high as possible.
This pump is the power plant for circulating cooling water in the motor vehicle. Therefore, the design parameters have two obvious characteristics: the flow is small and the rotating speed is high. Such special parameters, even for experienced engineers, are difficult to ensure the success rate of the design, requiring trial and error. This particular design task can obviously be solved as an optimization problem.
The first step, a parameter system is established in a hierarchical structure, and the method specifically comprises the following steps:
the parameters of the first hierarchy are: the number of blades;
the parameters of the second hierarchy are: bezier curve control point coordinate parameters of the front cover plate molded line; bezier curve control point coordinate parameters of the back cover plate molded line; coordinate parameters of the control points of the Bezier curve of the inlet side;
the parameters of the third level are: dimensionless Bezier curve control point coordinate parameters of camber lines of the blades on the flow surface;
the parameters of the fourth level are: thickness distribution of the blade.
Establishing a cooperative relation for the parameter system to reduce the number of free variables; the cooperative connection relation is specifically as follows:
S2-[1]S1_z＝H1_z
wherein s1_z represents the Z-axis coordinate of the front cover plate molded line control point S1, and h1_z represents the Z-axis coordinate of the rear cover plate molded line control point H1;
S2-[2]H2_x＝H1_x+kH2(H3_x-H1_x)
wherein, H2_x represents the X-axis coordinate of the back cover plate molded line control point H2, H2_x represents the X-axis coordinate of the back cover plate molded line control point H1, H2_x represents the X-axis coordinate of the back cover plate molded line control point H3, and kH2 represents the position coefficient of the control point H2;
S2-[3]H2_z＝H1_z+kH2(H3_z-H1_z)
wherein H2_z represents the Z-axis coordinate of the back cover plate molded line control point H2, and H2_z represents the Z-axis coordinate of the back cover plate molded line control point H3;
S2-[4]H4_x＝H3_x+kH4(H5_x-H3_x)
wherein, H4_x represents the X-axis coordinate of the back cover plate molded line control point H4, kH4 represents the position coefficient of the control point H4, and H5_x represents the X-axis coordinate of the back cover plate molded line control point H5;
S2-[5]H4_z＝H3_z+kH4(H5_z-H3_z)
wherein, H4_z represents the Z-axis coordinate of the back cover plate molded line control point H4, and H5_z represents the Z-axis coordinate of the back cover plate molded line control point H5;
S2-[6]S2_x＝S1_x+kS2(S3_x-S1_x)
wherein s2_x represents the X-axis coordinate of the front cover plate molded line control point S2, s1_x represents the X-axis coordinate of the front cover plate molded line control point S1, kS2 represents the position coefficient of the control point S2, and s3_x represents the X-axis coordinate of the front cover plate molded line control point S3;
S2-[7]S2_z＝S1_z+kS2(S3_z-S1_z)
wherein s2_z represents the Z-axis coordinate of the front cover plate molded line control point S2, s1_z represents the Z-axis coordinate of the front cover plate molded line control point S1, and s3_z represents the Z-axis coordinate of the front cover plate molded line control point S3;
S2-[8]S4_x＝S3_x+kS4(S5_x-S3_x)
wherein s4_x represents the X-axis coordinate of the front cover plate molded line control point S4, kS4 represents the position coefficient of the control point S4, and s5_x represents the X-axis coordinate of the front cover plate molded line control point S5;
S2-[9]S4_z＝S3_z+kS4(S5_z-S3_z)
wherein s4_z represents the Z-axis coordinate of the front cover plate molded line control point S4, and s5_z represents the Z-axis coordinate of the front cover plate molded line control point S5;
S2-[10]H5_z＝0；
S2-[11]LE2_x＝LE1_x+kLE2(LE3_x-LE1_x)
wherein, LE2_x represents the X-axis coordinate of the inlet edge line control point LE2, LE1_x represents the X-axis coordinate of the inlet edge line control point LE1, kLE2 represents the position coefficient of the control point LE2, and LE3_x represents the X-axis coordinate of the inlet edge line control point LE 3;
S2-[12]LE2_z＝LE1_z+kLE2(LE3_z-LE1_z)
wherein, LE2_z represents the Z-axis coordinate of the inlet edge line control point LE2, LE1_z represents the Z-axis coordinate of the inlet edge line control point LE1, and LE3_z represents the Z-axis coordinate of the inlet edge line control point LE 3;
S2-[13]LE4_x＝LE3_x+kLE4(LE5_x-LE3_x)
wherein, LE4_x represents the X-axis coordinate of the inlet edge line control point LE4, kLE4 represents the position coefficient of the control point LE4, and LE5_x represents the X-axis coordinate of the inlet edge line control point LE 5;
S2-[14]LE4_z＝LE3_z+kLE4(LE5_z-LE3_z)
wherein, LE4_z represents the Z-axis coordinate of the inlet edge line control point LE4, and LE5_z represents the Z-axis coordinate of the inlet edge line control point LE 5;
S2-[15]CS1_m＝CM1_m＝CH1_m＝0
wherein CS1_m represents the starting point coordinates of the mean camber line control point CS1 on the front deck flow surface, CM1_m represents the starting point coordinates of the mean camber line control point CM1 on the intermediate flow surface, and CH1_m represents the starting point coordinates of the mean camber line control point CH1 on the rear deck flow surface;
S2-[16]CS5_m＝CM5_m＝CH5_m＝1
wherein CS5_m represents the end point coordinates of the mean camber line control point CS5 on the flow surface of the front cover plate, CM5_m represents the end point coordinates of the mean camber line control point CM5 on the flow surface of the middle cover plate, and CH5_m represents the end point coordinates of the mean camber line control point CH1 on the flow surface of the rear cover plate;
S2-[17]bm1＝0
wherein bm1 represents the starting point coordinates of the chord length coordinates of the blade;
S2-[18]bm5＝1
wherein bm5 represents the endpoint coordinates of the blade chord length coordinates;
in practical application, a plurality of combinations can be selected from the 18 cooperative relationships S2 1-S2 18 as required, and all 18 cooperative relationships are selected in this embodiment.
Thirdly, establishing a general constraint relation for the parameter system, further reducing the number of free variables, and compressing the open design space of the variables; the general constraint relation is specifically:
s3 < 1 > the control point LE1 is on the front cover plate profile Curve. Shroud;
s3 < 2 > control point LE5 is on the back cover plate profile Curve. Hub;
s3- [3] the control point S3 is within a right triangle area formed by the control points (S1_x, S1_z), the control points (S5_x, S5_z) and the points (S1_x, S5_z);
the S3- [4] control point H3 is within the right triangle area formed by the control points (H1_x, H1_z), the control points (H5_x, H5_z) and the points (H1_x, H5_z);
s3- [5] control point LE3 is within a quadrilateral region of control points (LE1_x, LE1_z), points (LE1_x, LE5_z), control points (LE5_x, LE5_z), and points (LE5_x, LE1_z);
s3 < 6 > is further constrained by the control point H2 on a straight line defined by the control point H1 and the control point H3 according to the description of the cooperative connection relations S2 < 2 > and S2 < 3 >, and the control point H2 is on a line segment defined by the control point H1 and the control point H3; thus, the position of the control point H2 can be determined by using a length proportion k_H2 on the line segment, and the value range of the constraint proportion is [ k_H2min, k_H2max ];
s3 < 7 > is further constrained by the control point H4 on the straight line defined by the control point H3 and the control point H5 according to the description of the cooperative connection relations S2 < 4 > and S2 < 5 >, and the control point H4 is on the line segment defined by the control point H3 and the control point H5; thus, the position of the point H4 can be determined by using a length proportion k_H2 on the line segment, and the value range of the constraint proportion is [ k_H2min, k_H2max ];
s3 < 8 > is further constrained by the control point S2 on a straight line defined by the control point S1 and the control point S3, and the control point S2 on a line segment defined by the control point S1 and the control point S3, according to the descriptions of the cooperative connection relations S2 < 6 > and S2 < 7 >; thus, the position of the control point S2 can be determined by using a length proportion k_S2 on the line segment, and the value range of the constraint proportion is [ k_S2min, k_S2max ];
s3-9 is further constrained by the control point S4 on the line defined by the control point S3 and the control point S5 according to the description of the cooperative connection relation S2-8 and S2-9, and the control point S4 is on the line segment defined by the control point S3 and the control point S5, so that the position of the control point S4 can be defined by a length proportion k-S4 on the line segment, and the value range of the constraint proportion is [ k-S4 min, k-S4 max ];
s3- [10] is further constrained by the control point LE2 on the straight line defined by the control point LE1 and the control point LE3 according to the description of the cooperative relationship S2- [11] and S2- [12], and the control point LE2 is on the line segment defined by the control point LE1 and the control point LE3, so that the position of the control point LE2 can be defined by a length proportion k_LE2 on the line segment, and the value range of the constraint proportion is [ k_LE2min, k_LE2max ];
s3- [11] is further constrained by the control point LE4 on the line defined by the control point LE3 and the control point LE5 according to the description of the cooperative relationship S2- [13] and S2- [14], and the control point LE4 is on the line segment defined by the control point LE3 and the control point LE5, so that the position of the control point LE4 can be defined by a length proportion k_LE4 on the line segment, and the value range of the constraint proportion is [ k_LE4min, k_LE4max ];
S3-[12]CS1_m＜CS2_m＜CS3_m＜CS4_m＜CS5_m
wherein CS2_m represents the relative streamline position of the mean camber line control point CS2 on the flow surface of the front cover plate, CS3_m represents the relative streamline position of the mean camber line control point CS3 on the flow surface of the front cover plate, CS4_m represents the relative streamline position of the mean camber line control point CS4 on the flow surface of the front cover plate;
S3-[13]thetamin≤CS1_t＜CS2_t＜CS3_t＜CS4_t＜CS5_t≤thetamax
wherein, thetamin represents the minimum value of the blade inlet edge wrap angle, CS1_t represents the wrap angle value of a mean camber line control point CS1 on the flow surface of the front cover plate, CS2_t represents the wrap angle value of a mean camber line control point CS2 on the flow surface of the front cover plate, CS3_t represents the wrap angle value of a mean camber line control point CS3 on the flow surface of the front cover plate, CS4_t represents the wrap angle value of a mean camber line control point CS4 on the flow surface of the front cover plate, CS5_t represents the wrap angle value of a mean camber line control point CS5 on the flow surface of the front cover plate, and theta max represents the maximum value of the blade inlet edge wrap angle;
S3-[14]CH1_m＜CH2_m＜CH3_m＜CH4_m＜CH5_m
wherein ch2_m represents the relative streamline position of the mean camber line control point CH2 on the back-cover plate flow surface, ch3_m represents the relative streamline position of the mean camber line control point CH3 on the back-cover plate flow surface, ch4_m represents the relative streamline position of the mean camber line control point CH4 on the back-cover plate flow surface;
S3-[15]thetamin≤CH1_t＜CH2_t＜CH3_t＜CH4_t＜CH5_t≤thetamax
wherein ch1_t represents the wrap angle value of the mean camber line control point CH1 on the back-cover plate flow surface, ch2_t represents the wrap angle value of the mean camber line control point CH2 on the back-cover plate flow surface, ch3_t represents the wrap angle value of the mean camber line control point CH3 on the back-cover plate flow surface, ch4_t represents the wrap angle value of the mean camber line control point CH4 on the back-cover plate flow surface, ch5_t represents the wrap angle value of the mean camber line control point CH5 on the back-cover plate flow surface;
S3-[16]CM1_m＜CM2_m＜CM3_m＜CM4_m＜CM5_m
wherein cm2_m represents the relative streamline position of the mean camber line control point CM2 on the intermediate flow surface, cm3_m represents the relative streamline position of the mean camber line control point CM3 on the intermediate flow surface, and cm4_m represents the relative streamline position of the mean camber line control point CM4 on the intermediate flow surface;
S3-[17]thetamin≤CM1_t＜CM2_t＜CM3_t＜CM4_t＜CM5_t≤thetamax
wherein cm1_t represents the wrap angle value of the mean camber line control point CM1 on the intermediate flow surface, cm2_t represents the wrap angle value of the mean camber line control point CM2 on the intermediate flow surface, cm3_t represents the wrap angle value of the mean camber line control point CM3 on the intermediate flow surface, cm4_t represents the wrap angle value of the mean camber line control point CM4 on the intermediate flow surface, and cm5_t represents the wrap angle value of the mean camber line control point CM5 on the intermediate flow surface;
S3-[18]0＜STHK_n≤HTHK_n
wherein sthk_n represents the thickness values of the thickness control points 1-5 on the front cover plate flow surface of the blade, n=1, 2, 3, 4, 5, hthk_n represents the thickness values of the thickness control points 1-5 on the back cover plate flow surface of the blade;
S3-[19]max(STHK_n)≤kTS*min(STHK_n)
wherein kTS represents the ratio of the maximum thickness to the minimum thickness at each location on the flow surface of the blade front cover plate;
S3-[20]max(HTHK_n)≤kTH*min(HTHK_n)
wherein kTH represents the ratio of the maximum thickness to the minimum thickness at each location on the flow surface of the blade back cover plate;
in this embodiment, general constraint relationships S3 1-S3 5 are enabled; for general constraint relations S3-S3 11, the constraint ratio range values are all 0.2, 0.8; taking thetamin=0 and thetamax=180 for general constraint relations S3- [13], S3- [15], S3- [17 ]; taking sthk_n=hthk_n for general constraint relation s3- [18 ]; for general constraint relations S3- [19] to S3- [20], kTS = kTH =1 is taken.
And fourthly, adding auxiliary constraint to the parameter system according to the optimization problem, and reducing the parameter dimension. The simplest way of thickness description parameters may be a single thickness; in this embodiment, the thickness description is reduced to a single thickness. The inlet edge profile can be reduced from a four-time Bezier curve to a one-time Bezier curve; in this embodiment, the inlet edge profile is reduced to a one-time Bezier curve. The wrap angle control curve can be reduced from a four-time Bezier curve to a two-time Bezier curve or a three-time Bezier curve, and the effect of the two curves is different for impellers with different specific speeds, but the effect is not better than the three times of the two curves. In this embodiment, the wrap angle control curve is reduced to a cubic bezier curve. Adding a set of constraint relationships:
S4-[1]CS1_t＝CM1_t＝CH1_t＝0；
S4-[2]CS5_t＝CM5_t＝CH5_t；
the profile of the front cover plate and the rear cover plate can be reduced from a four-time Bezier curve to a two-time one; in this embodiment, the front and rear cover plate profiles retain the original four-time bezier curves. The center curve control point of the middle flow surface directly takes the median value of the corresponding points of the front cover plate and the rear cover plate, and all the free parameters on the flow surface are eliminated. The auxiliary constraint can be used for selecting one or more of the auxiliary constraints according to actual conditions.
Through the steps, the original parameter system is reduced from 76 degrees of freedom to 24 degrees of freedom. The 24 degrees of freedom are also relatively large and are not suitable for one-time processing. Therefore, hierarchical processing optimizing is carried out according to hierarchical division, and a strategy of repeated iteration is adopted. Through the parameter system and the collocation optimization algorithm, a better effect is finally obtained. In the embodiment, the layering processing is performed on the parameters, so that the optimization theory is facilitated to batch process various parameters in the processing process, the number of parameters needing to be processed simultaneously is reduced, and the robustness and stability of the processing process are improved. Layering parameters, wherein the main basis is as follows: the step characteristics of the impeller modeling process are determined by the characteristics of the optimization algorithm on parameter processing. The constraint relation is added to the parameters, so that the number of parameters to be processed in each step of each layer is reduced, and the operation efficiency of an optimization algorithm and a processing process is increased. The main basis is: the constraint relation is increased from the geometric sense, so that the impeller can be generated according to the correct geometric topology. In addition, in the process of constructing the geometry, the main contradiction is grasped preferentially, the secondary contradiction is ignored, and some non-main parameters are defined in a form of a cooperative connection relationship and are attached to the main parameters.
We devised several strategies to accomplish the task and compared the effects and results of several strategies, as shown in table 2:
TABLE 2 design Effect under different strategies
| Robustness (robustness) | Design effect/efficiency | |
| Empirical design 1# | Excellent (excellent) | In general |
| Empirical design 2# | Excellent (excellent) | In general |
| General parameter System | Difference of difference | - |
| The parameter system of the invention | Excellent (excellent) | Excellent (excellent) |
By empirical design, the robustness of the overall design process is very good, but its design effectiveness is relatively modest over a defined period of time. In a general parameter system, the gradient range cannot be determined after the evaluation system receives feedback due to excessive variables, and the constraint on the variables is lacking, so that the feedback received by the evaluation system is invalid in a large proportion. Therefore, the robustness of the whole system is very poor, and the system is extremely easy to run. The parameter system of the technical scheme is characterized in that a parameter system with a framework hierarchy structure is constructed, and each geometrical characteristic has a corresponding free parameter belonging to a specific hierarchy; this allows the subsequent optimization system to take place in a branched structure when dealing with both continuous and discrete variables; the architecture design of the optimization system is greatly facilitated; the dimension and the range of a parameter space can be reduced by establishing a cooperative connection relation and a constraint relation for the parameter system, and the working efficiency of the optimization system is exponentially improved; secondly, most unreasonable combination parameter combinations can be removed, so that a feedback mechanism of the optimization system can be ensured to run stably, and the robustness of the optimization system is improved; the method well solves the number problem of variables and the constraint problem of the variables, accelerates the optimization process, and obtains more excellent design results than an empirical method. The efficiency of the water pump impeller obtained by adopting an empirical method is 82.1%, and the impeller efficiency reaches 84.2% by adopting the parameter system matched with the result obtained by the optimization algorithm, and the iterative processing steps can be used when the parameter space is explored by adopting the parameter system with the framework hierarchical structure; thereby reducing the time consumed by the optimizing system to complete a task; the operation efficiency of the system is improved.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and variations could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.
Claims (4)
1. The method for establishing the parameter system of the centrifugal pump impeller is characterized by comprising the following steps of:
establishing a parameter system in a hierarchical structure;
establishing a cooperative connection relation for a parameter system;
establishing a general constraint relation for a parameter system;
adding auxiliary constraint to the parameter system according to the optimization problem;
the parameter system is established in a hierarchical structure, and specifically comprises the following steps:
the parameters of the first hierarchy include: the number of blades;
parameters of the second hierarchy include: bezier curve control point coordinate parameters of the front cover plate molded line; bezier curve control point coordinate parameters of the back cover plate molded line; coordinate parameters of the control points of the Bezier curve of the inlet side;
the parameters of the third level include: dimensionless Bezier curve control point coordinate parameters of camber lines of the blades on the flow surface;
parameters of the fourth level include: thickness distribution of the blade;
the auxiliary constraints include one or more of the following auxiliary constraints:
the thickness descriptive parameter is a single thickness;
the line of the inlet edge is reduced from a four-time Bezier curve to a one-time Bezier curve;
the wrap angle control curve is reduced from a fourth Bezier curve to a second Bezier curve;
the front cover plate profile is reduced from a four-time Bezier curve to a two-time Bezier curve;
the center curve control point of the middle flow surface directly takes the median value of the corresponding points of the front cover plate and the rear cover plate.
2. The method for establishing a parameter system of a centrifugal pump impeller according to claim 1, wherein the cooperative relationship comprises one or more of the following cooperative relationships:
S2-[1]S1_z＝H1_z
wherein s1_z represents the Z-axis coordinate of the front cover plate molded line control point S1, and h1_z represents the Z-axis coordinate of the rear cover plate molded line control point H1;
S2-[2]H2_x＝H1_x+kH2(H3_x-H1_x)
wherein, H2_x represents the X-axis coordinate of the back cover plate molded line control point H2, H2_x represents the X-axis coordinate of the back cover plate molded line control point H1, H2_x represents the X-axis coordinate of the back cover plate molded line control point H3, and kH2 represents the position coefficient of the control point H2;
S2-[3]H2_z＝H1_z+kH2(H3_z-H1_z)
wherein H2_z represents the Z-axis coordinate of the back cover plate molded line control point H2, and H2_z represents the Z-axis coordinate of the back cover plate molded line control point H3;
S2-[4]H4_x＝H3_x+kH4(H5_x-H3_x)
wherein, H4_x represents the X-axis coordinate of the back cover plate molded line control point H4, kH4 represents the position coefficient of the control point H4, and H5_x represents the X-axis coordinate of the back cover plate molded line control point H5;
S2-[5]H4_z＝H3_z+kH4(H5_z-H3_z)
wherein, H4_z represents the Z-axis coordinate of the back cover plate molded line control point H4, and H5_z represents the Z-axis coordinate of the back cover plate molded line control point H5;
S2-[6]S2_x＝S1_x+kS2(S3_x-S1_x)
wherein s2_x represents the X-axis coordinate of the front cover plate molded line control point S2, s1_x represents the X-axis coordinate of the front cover plate molded line control point S1, kS2 represents the position coefficient of the control point S2, and s3_x represents the X-axis coordinate of the front cover plate molded line control point S3;
S2-[7]S2_z＝S1_z+kS2(S3_z-S1_z)
wherein s2_z represents the Z-axis coordinate of the front cover plate molded line control point S2, s1_z represents the Z-axis coordinate of the front cover plate molded line control point S1, and s3_z represents the Z-axis coordinate of the front cover plate molded line control point S3;
S2-[8]S4_x＝S3_x+kS4(S5_x-S3_x)
wherein s4_x represents the X-axis coordinate of the front cover plate molded line control point S4, kS4 represents the position coefficient of the control point S4, and s5_x represents the X-axis coordinate of the front cover plate molded line control point S5;
S2-[9]S4_z＝S3_z+kS4(S5_z-S3_z)
wherein s4_z represents the Z-axis coordinate of the front cover plate molded line control point S4, and s5_z represents the Z-axis coordinate of the front cover plate molded line control point S5;
S2-[10]H5_z＝0；
S2-[11]LE2_x＝LE1_x+kLE2(LE3_x-LE1_x)
wherein, LE2_x represents the X-axis coordinate of the inlet edge line control point LE2, LE1_x represents the X-axis coordinate of the inlet edge line control point LE1, kLE2 represents the position coefficient of the control point LE2, and LE3_x represents the X-axis coordinate of the inlet edge line control point LE 3;
S2-[12]LE2_z＝LE1_z+kLE2(LE3_z-LE1_z)
wherein, LE2_z represents the Z-axis coordinate of the inlet edge line control point LE2, LE1_z represents the Z-axis coordinate of the inlet edge line control point LE1, and LE3_z represents the Z-axis coordinate of the inlet edge line control point LE 3;
S2-[13]LE4_x＝LE3_x+kLE4(LE5_x-LE3_x)
wherein, LE4_x represents the X-axis coordinate of the inlet edge line control point LE4, kLE4 represents the position coefficient of the control point LE4, and LE5_x represents the X-axis coordinate of the inlet edge line control point LE 5;
S2-[14]LE4_z＝LE3_z+kLE4(LE5_z-LE3_z)
wherein, LE4_z represents the Z-axis coordinate of the inlet edge line control point LE4, and LE5_z represents the Z-axis coordinate of the inlet edge line control point LE 5;
S2-[15]CS1_m＝CM1_m＝CH1_m＝0
wherein CS1_m represents the starting point coordinates of the mean camber line control point CS1 on the front deck flow surface, CM1_m represents the starting point coordinates of the mean camber line control point CM1 on the intermediate flow surface, and CH1_m represents the starting point coordinates of the mean camber line control point CH1 on the rear deck flow surface;
S2-[16]CS5_m＝CM5_m＝CH5_m＝1
wherein CS5_m represents the end point coordinates of the mean camber line control point CS5 on the flow surface of the front cover plate, CM5_m represents the end point coordinates of the mean camber line control point CM5 on the flow surface of the middle cover plate, and CH5_m represents the end point coordinates of the mean camber line control point CH1 on the flow surface of the rear cover plate;
S2-[17]bm1＝0
wherein bm1 represents the starting point coordinates of the chord length coordinates of the blade;
S2-[18]bm5＝1
where bm5 represents the endpoint coordinate of the blade chord coordinate.
3. The method for establishing a parameter system of a centrifugal pump impeller according to claim 2, wherein the general constraint relation comprises:
s3 < 1 > the control point LE1 is on the front cover plate profile Curve. Shroud;
s3 < 2 > control point LE5 is on the back cover plate profile Curve. Hub;
s3- [3] the control point S3 is within a right triangle area formed by the control points (S1_x, S1_z), the control points (S5_x, S5_z) and the points (S1_x, S5_z);
the S3- [4] control point H3 is within the right triangle area formed by the control points (H1_x, H1_z), the control points (H5_x, H5_z) and the points (H1_x, H5_z);
s3- [5] control point LE3 is within a quadrilateral region of control points (LE1_x, LE1_z), points (LE1_x, LE5_z), control points (LE5_x, LE5_z), and points (LE5_x, LE1_z);
s3 < 6 > is further constrained by the control point H2 on a straight line defined by the control point H1 and the control point H3 according to the description of the cooperative connection relations S2 < 2 > and S2 < 3 >, and the control point H2 is on a line segment defined by the control point H1 and the control point H3; the position of the control point H2 can be determined by using a length proportion k_H2 on the line segment, and the value range of the constraint proportion is [ k_H2min, k_H2max ];
s3 < 7 > is further constrained by the control point H4 on the straight line defined by the control point H3 and the control point H5 according to the description of the cooperative connection relations S2 < 4 > and S2 < 5 >, and the control point H4 is on the line segment defined by the control point H3 and the control point H5; the position of the point H4 can be determined by using a length proportion k_H2 on the line segment, and the value range of the constraint proportion is [ k_H2min, k_H2max ];
s3 < 8 > is further constrained by the control point S2 on a straight line defined by the control point S1 and the control point S3, and the control point S2 on a line segment defined by the control point S1 and the control point S3, according to the descriptions of the cooperative connection relations S2 < 6 > and S2 < 7 >; the position of the control point S2 can be determined by using a length proportion k_S2 on the line segment, and the value range of the constraint proportion is [ k_S2min, k_S2max ];
s3- [9] according to the description of the cooperative connection relation S2- [8] and S2- [9], the control point S4 is further constrained on a straight line determined by the control point S3 and the control point S5, the control point S4 is on a line segment determined by the control point S3 and the control point S5, the position of the control point S4 can be determined by using a length proportion k_S4 on the line segment, and the value range of the constraint proportion is [ k_S4min, k_S4max ];
s3- [10] according to the description of the cooperative connection relation S2- [11] and S2- [12], the control point LE2 is further constrained on a straight line determined by the control point LE1 and the control point LE3, the control point LE2 is on a line segment determined by the control point LE1 and the control point LE3, the position of the control point LE2 can be determined by using a length proportion k_LE2 on the line segment, and the value range of the constraint proportion is [ k_LE2min, k_LE2max ];
s3- [11] according to the description of the cooperative connection relation S2- [13] and S2- [14], the control point LE4 is further constrained on a straight line determined by the control point LE3 and the control point LE5, the control point LE4 is on a line segment determined by the control point LE3 and the control point LE5, the position of the control point LE4 can be determined by using a length proportion k_LE4 on the line segment, and the value range of the constraint proportion is [ k_LE4min, k_LE4max ];
S3-[12]CS1_m＜CS2_m＜CS3_m＜CS4_m＜CS5_m
wherein CS2_m represents the relative streamline position of the mean camber line control point CS2 on the flow surface of the front cover plate, CS3_m represents the relative streamline position of the mean camber line control point CS3 on the flow surface of the front cover plate, CS4_m represents the relative streamline position of the mean camber line control point CS4 on the flow surface of the front cover plate;
S3-[13]thetamin≤CS1_t＜CS2_t＜CS3_t＜CS4_t＜CS5_t≤thetamax
wherein, thetamin represents the minimum value of the blade inlet edge wrap angle, CS1_t represents the wrap angle value of a mean camber line control point CS1 on the flow surface of the front cover plate, CS2_t represents the wrap angle value of a mean camber line control point CS2 on the flow surface of the front cover plate, CS3_t represents the wrap angle value of a mean camber line control point CS3 on the flow surface of the front cover plate, CS4_t represents the wrap angle value of a mean camber line control point CS4 on the flow surface of the front cover plate, CS5_t represents the wrap angle value of a mean camber line control point CS5 on the flow surface of the front cover plate, and theta max represents the maximum value of the blade inlet edge wrap angle;
S3-[14]CH1_m＜CH2_m＜CH3_m＜CH4_m＜CH5_m
wherein ch2_m represents the relative streamline position of the mean camber line control point CH2 on the back-cover plate flow surface, ch3_m represents the relative streamline position of the mean camber line control point CH3 on the back-cover plate flow surface, ch4_m represents the relative streamline position of the mean camber line control point CH4 on the back-cover plate flow surface;
S3-[15]thetamin≤CH1_t＜CH2_t＜CH3_t＜CH4_t＜CH5_t≤thetamax
wherein ch1_t represents the wrap angle value of the mean camber line control point CH1 on the back-cover plate flow surface, ch2_t represents the wrap angle value of the mean camber line control point CH2 on the back-cover plate flow surface, ch3_t represents the wrap angle value of the mean camber line control point CH3 on the back-cover plate flow surface, ch4_t represents the wrap angle value of the mean camber line control point CH4 on the back-cover plate flow surface, ch5_t represents the wrap angle value of the mean camber line control point CH5 on the back-cover plate flow surface;
S3-[16]CM1_m＜CM2_m＜CM3_m＜CM4_m＜CM5_m
wherein cm2_m represents the relative streamline position of the mean camber line control point CM2 on the intermediate flow surface, cm3_m represents the relative streamline position of the mean camber line control point CM3 on the intermediate flow surface, and cm4_m represents the relative streamline position of the mean camber line control point CM4 on the intermediate flow surface;
S3-[17]thetamin≤CM1_t＜CM2_t＜CM3_t＜CM4_t＜CM5_t≤thetamax
wherein cm1_t represents the wrap angle value of the mean camber line control point CM1 on the intermediate flow surface, cm2_t represents the wrap angle value of the mean camber line control point CM2 on the intermediate flow surface, cm3_t represents the wrap angle value of the mean camber line control point CM3 on the intermediate flow surface, cm4_t represents the wrap angle value of the mean camber line control point CM4 on the intermediate flow surface, and cm5_t represents the wrap angle value of the mean camber line control point CM5 on the intermediate flow surface;
S3-[18]0＜STHK_n≤HTHK_n
wherein sthk_n represents the thickness values of the thickness control points 1-5 on the front cover plate flow surface of the blade, n=1, 2, 3, 4, 5, hthk_n represents the thickness values of the thickness control points 1-5 on the back cover plate flow surface of the blade;
S3-[19]max(STHK_n)≤kTS*min(STHK_n)
wherein kTS represents the ratio of the maximum thickness to the minimum thickness at each location on the flow surface of the blade front cover plate;
S3-[20]max(HTHK_n)≤kTH*min(HTHK_n)
wherein kTH represents the ratio of the maximum thickness to the minimum thickness at each location on the flow surface of the blade back cover plate.
4. A method for establishing a parameter system for a centrifugal pump impeller according to claim 3, wherein,
in general constraint relation S3-S3 11, the value ranges of length proportion k_H2, length proportion k_S2, length proportion k_S4, length proportion k_LE2 and length proportion k_LE4 are all 0.2, 0.8;
taking thetamin=0 and thetamax=180 for general constraint relations S3- [13], S3- [15], S3- [17 ];
taking sthk_n=hthk_n for general constraint relation s3- [18 ];
for general constraint relations S3- [19] to S3- [20], kTS = kTH =1 is taken.
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