Quantitative evaluation method and system for flow passage overflowing section of pump impeller

Abstract

The invention provides a quantitative evaluation method and system for an overflowing section of a pump impeller runner. The quantitative evaluation method comprises the following steps that after parameterization is conducted on the pump impeller runner needing to be evaluated, the overflowing section area of the runner is obtained through calculation; fitting is carried out on the basis of the overflowing section area to obtain an overflowing section area change curve; carrying out primary degradation statistics on the over-current section area change curve to obtain the number Ex of extreme points, and then sequentially carrying out secondary degradation and branching processing to obtain a first change curve and a second change curve; based on the first change curve and the second change curve, a first absolute value integral T1 and a second absolute value integral T2 are obtained through calculation; and performing performance evaluation on the overflowing section based on the number Ex of the extreme points, the first absolute value integral T1 and the second absolute value integral T2 to obtain an evaluation result of the pump impeller passage. The method improves the accuracy of performance evaluation of the pump impeller runner, effectively predicts and improves the performance of the pump, reduces the operation cost and the maintenance cost, and prolongs the service life.

Description

Technical Field

[0001] The present invention belongs to the technical field of detecting flow components of rotating machinery, and specifically belongs to a method and system for quantitatively evaluating the flow cross-section of a pump impeller passage. Background Art

[0002] A pump is an important energy conversion and fluid transportation equipment with a wide variety of types and large production. As a general machinery, it has been widely used in various sectors of the national economy. In China, the power consumption of pumps accounts for about 20% of the total national power consumption, which is huge, and the energy-saving situation is very serious. Among them, the energy consumption of impeller machinery such as centrifugal pumps and mixed-flow pumps mainly occurs in the impeller. The energy consumption not only depends on the hydraulic efficiency of the impeller. Therefore, when operating under off-design conditions, the influence of cavitation on the hydraulic efficiency needs to be considered. The traditional design method of the impeller passage is an empirical design method based on the one-dimensional design theory. When quantitatively evaluating the flow cross-section of the pump impeller passage, this method mainly refers to similar previous hydraulic models, and the staff needs to rely on their own experience. After the flow passage is designed, when it is necessary to verify the change curve of the flow cross-section area, the verification result is obtained by the staff observing the change curve of the flow cross-section area. It is impossible to quantitatively analyze the quality of the curve, and it is limited to ensuring that the curve is partially linear, without considering the cavitation performance. Moreover, during the manual observation process, it is easy to be interfered by external factors, resulting in large evaluation errors, and further leading to obvious performance differences in the pump body. Summary of the Invention

[0003] In order to solve the problem that the existing evaluation of the flow cross-section of the pump impeller is carried out through the staff's own experience, which is limited to ensuring that the curve is partially linear and results in large evaluation errors, the present invention provides To achieve the above object, the present invention provides the following technical solutions: The present invention proposes a method for quantitatively evaluating the flow cross-section of a pump impeller passage, including the following steps: After parameterizing the pump impeller passage to be evaluated, calculate the flow cross-section area; Based on the flow cross-section area, fit the change curve of the flow cross-section area; Perform a first-level degradation statistics on the change curve of the flow cross-section area to obtain the number of extreme points E x Then, perform secondary degradation and line division processing in sequence to obtain the first change curve and the second change curve; Based on the first change curve and the second change curve, calculate the first absolute value integral T 1 and the second absolute value integral T 2 ; Based on the number of extreme points E x and the first absolute value integral T 1and the second absolute value integral T 2 Performance evaluation of the cross-sectional area of flow is carried out to obtain the evaluation results of the impeller passage.

[0004] Preferably, after parameterizing the impeller passage to be evaluated, the cross-sectional area of the flow passage is calculated, including:[[]] Parameterize the Bezier curve of the passage profile of the impeller passage to obtain the coordinates of the first control points of the hub curve and the coordinates of the second control points of the shroud curve; Calculate the coordinates of the control points of the center line of the flow passage based on the coordinates of the first control points and the coordinates of the second control points; Fit the center line of the flow passage based on the coordinates of the control points; Calculate the cross-sectional area of the flow passage based on multiple third control points selected on the center line of the flow passage.

[0005] Preferably, calculating the cross-sectional area of the flow passage based on multiple third control points selected on the center line of the flow passage includes:[[]] Arbitrarily select multiple points on the center line of the flow passage and denote them as third control points; Draw an inscribed circle with a radius of r with the third control point as the center. The tangent point of the inscribed circle and the hub curve is marked as tangent point A, and the tangent point of the inscribed circle and the shroud curve is marked as tangent point B; Divide the perpendicular distance between the center of the circle and tangent point A and tangent point B into equal parts to obtain equal division points; Obtain the arc length between the equal division points, tangent point A, and tangent point B to get the arc length ; Based on obtaining the axial distance R from the center of the circle to the center hole of the impeller c and the arc length Calculate the cross-sectional area F of the flow passage p .

[0006] Preferably, the calculation process of calculating the cross-sectional area F of the flow passage based on obtaining the axial distance R from the center of the circle to the center hole of the impeller c and the arc length is as follows:[[]] p The calculation process is:[[]]

[0007] wherein, is the axial distance from the center of the circle to the center hole of the impeller, is the length of the arc.

[0008] Preferably, fitting the cross-sectional area change curve based on the cross-sectional area of the flow passage includes:[[]] Obtain the percentage length of the center line of the flow channel; Construct change curve coordinate points based on the percentage length and the cross-sectional area of the flow channel; Fit the cross-sectional area change curve in a rectangular coordinate system based on the change curve coordinate points.

[0009] Preferably, perform a first-order degradation statistics on the cross-sectional area change curve to obtain the number of extreme points E x , including: Divide the cross-sectional area change curve into multiple equal segments, mark the endpoints of each segment after the multiple equal divisions as discrete points, and obtain the coordinate data of the discrete points to get the first discrete point coordinates, which are denoted as F k [x k ,y k , where k≥0; Perform a first-order degradation based on two adjacent first discrete point coordinates to obtain a first derivative value, and denote the second discrete point coordinates of the first discrete point coordinates after the first-order degradation as F1 i [x i , y i , where 0≤j<k; Statistically obtain the number of extreme points E based on the first derivative value x .

[0010] Preferably, the second-order degradation and line division processing to obtain the first change curve and the second change curve include: Fit a first derivative curve based on the first derivative value; Perform a second-order degradation on the first derivative curve to obtain a second derivative value, and denote the third discrete point coordinates obtained after the second-order degradation of the second discrete point coordinates as F2 j [x j , y j , 0≤j<i; Fit a second derivative curve based on the second derivative value; Take the third discrete point coordinates corresponding to the center of the center line of the flow channel as the segmentation point, and divide the second derivative curve into two segments, one of which is marked as the first change curve f 2a , and the other segment is marked as the second change curve f 2b ; then the third discrete point coordinates in the first change curve f 2a are marked as the first change curve discrete point coordinates F2 a j [x aj , y aj , 0≤aj<i / 2; the third discrete point coordinates in the second change curve f 2a are marked as the second change curve discrete point coordinates F2bj [x bj , y bj , 0 ≤ bj < i / 2; The first absolute integral T is calculated based on the discrete point coordinates of the first change curve and the discrete point coordinates of the second change curve respectively 1 and the second absolute integral T 2 .

[0011] Preferably, the first absolute integral T is calculated based on the discrete point coordinates of the first change curve 1 The calculation process is as follows:

[0012] Where is the ordinate value of the discrete point coordinate F2 of the first change curve aj of, is the ordinate value of the coordinate point adjacent to the discrete point coordinate F2 of the first change curve aj , is the abscissa value of the discrete point coordinate F2 of the first change curve aj of, is the abscissa value of the coordinate point adjacent to the discrete point coordinate F2 of the first change curve aj ; The second absolute integral T is calculated based on the discrete point coordinates of the second change curve 2 The calculation process is;

[0013] Where is the ordinate value of the discrete point coordinate F2 of the first change curve bj of, is the ordinate value of the coordinate point adjacent to the discrete point coordinate F2 of the first change curve bj , is the abscissa value of the discrete point coordinate F2 of the first change curve bj of, is the abscissa value of the coordinate point adjacent to the discrete point coordinate F2 of the first change curve bj .

[0014] Preferably, based on the number of extreme points E x , the first absolute integral T 1 and the second absolute integral T 2 perform a performance evaluation on the cross-section of the overflow to obtain an evaluation result, including: Compare the number of extreme points E x with the preset first preset extreme point value and the second preset extreme point value respectively, and compare the first absolute integral T 1Compare with a preset first preset integral range and a preset second preset integral range respectively; compare the second absolute value integral T 2 Compare with a preset third preset integral range and a preset fourth preset integral range respectively; When the number of extreme points E x Does not exceed the first preset extreme value number, and the first absolute value integral T 1 Is within the first preset integral range, then it is evaluated that the cavitation performance of the pump impeller flow passage is average, and the second absolute value integral T 2 Is within the third preset integral range, the second absolute value integral T 2 The smaller it is, the better the hydraulic performance of the pump impeller flow passage is evaluated; When the number of extreme points E x Is equal to the second preset extreme value number, and the first absolute value integral T 1 Is within the second preset integral range, then it is evaluated that the cavitation performance of the pump impeller flow passage is good, and the second absolute value integral T 2 Is within the fourth preset integral range, the second absolute value integral T 2 The smaller it is, the better the hydraulic performance of the pump impeller flow passage is evaluated; When the number of extreme points E x Exceeds the second preset extreme value number, then it is evaluated that both the hydraulic performance and cavitation performance of the pump impeller flow passage are poor.

[0015] The present invention provides a quantitative evaluation system for the flow-through cross-section of a pump impeller flow passage to implement the above evaluation method, including: A first processing unit for calculating the flow-through cross-section area after parameterizing the pump impeller flow passage to be evaluated; A fitting unit for fitting a flow-through cross-section area change curve based on the flow-through cross-section area; A second processing unit for performing a first-level degradation statistics on the flow-through cross-section area change curve to obtain the number of extreme points E x After that, perform secondary degradation and line division processing in sequence to obtain a first change curve and a second change curve; A third processing unit for calculating a first absolute value integral T 1 And a second absolute value integral T 2 Based on the first change curve and the second change curve respectively; An evaluation unit for based on the number of extreme points E x 、the first absolute value integral T 1 And the second absolute value integral T 2The performance of the cross-sectional area is evaluated to obtain the evaluation result of the impeller passage of the pump. An output unit for outputting the evaluation result of the impeller passage of the pump.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention proposes a quantitative evaluation method for the cross-sectional area of the impeller passage of a pump. By parameterizing the impeller passage of the pump, the cross-sectional area of the passage can be accurately calculated. Using these area data, a curve of the change in the cross-sectional area is fitted to intuitively understand the dynamic characteristics of the fluid flow in the passage. Through degradation statistics and line division processing of the change curve, a first change curve and a second change curve are obtained, and the first absolute value integral T 1 and the second absolute value integral T 2 are respectively calculated. The first absolute value integral T 1 and the second absolute value integral T 2 reflect the smoothness and uniformity of the fluid flow in the passage. Combining the number of extreme points Ex, the first absolute value integral T1, and the second absolute value integral T2, a comprehensive performance evaluation of the impeller passage of the pump can be carried out, not only considering the change in the passage area, but also fully considering the smoothness and uniformity of the fluid flow, so as to more accurately reflect the actual performance of the impeller passage of the pump. Furthermore, this method has significant superiority and practicability. It can not only improve the accuracy of the performance evaluation of the impeller passage of the pump, but also provide strong support for the design and optimization of the pump, effectively predict and improve the performance of the pump, thereby improving its working efficiency and service life, and reducing the operation cost and maintenance cost.

[0017] Furthermore, by parameterizing the Bezier curve of the passage profile of the impeller passage, the control point coordinates of the hub curve and the shroud curve can be accurately obtained. Based on the control point coordinates, the control point coordinates of the center line of the passage are calculated, and the center line of the passage is fitted to more accurately grasp the geometric shape of the passage. Multiple third control points are selected on the center line of the passage, and the cross-sectional area is calculated using these points, which can detail the fluid flow conditions at different positions in the passage, improve the accuracy of the evaluation, achieve the accurate calculation of the cross-sectional area of the impeller passage of the pump, improve the working efficiency and service life of the pump, and also reduce the operation cost and maintenance cost.

[0018] Furthermore, in this method, multiple points are arbitrarily selected on the center line of the flow channel as the third control points. These points can comprehensively reflect the geometric characteristics of the flow channel. Taking these control points as the centers, inscribed circles are drawn. The tangent points with the hub curve and the shroud curve are marked as A and B respectively, ensuring the accuracy of the calculation. The perpendicular distances between the center and the tangent points A and B are equally divided to obtain equally divided points, which facilitates the subsequent calculation of the arc length. By obtaining the arc lengths between the equally divided point E, the tangent point A, and the tangent point B , the shape of the flow channel cross-section can be more accurately described. Combining the distance Rc from the center of the impeller to the axis of the central hole of the impeller and the arc length , the cross-sectional area Fp of the flow-through section is calculated, improving the accuracy of the calculation and avoiding the possible errors and uncertainties in the traditional method.

[0019] Furthermore, in this method, by obtaining the percentage length of the center line of the flow channel and the corresponding cross-sectional area of the flow-through section, the coordinate points of the change curve are constructed, and the change curve of the cross-sectional area of the flow-through section is fitted in the rectangular coordinate system, enabling an intuitive understanding of the dynamic changes of the fluid flow cross-section in the flow channel. The change curve of the cross-sectional area of the flow-through section is subjected to a first-order degradation statistics. Through multi-segment equal division and obtaining the endpoint coordinate data, the first discrete point coordinates are obtained. Based on the adjacent two first discrete point coordinates, a first-order degradation is performed to calculate the first derivative value, which is marked as the second discrete point coordinates, simplifying the data processing process and improving the accuracy of the statistics. Based on the first derivative value, the number of extreme points Ex is statistically obtained, which can reflect the change degree and frequency of the fluid flow cross-section in the flow channel. By constructing the change curve of the cross-sectional area of the flow-through section and performing a first-order degradation statistics, the dynamic changes and extreme points of the fluid flow cross-section in the flow channel are accurately quantified, improving the accuracy of the evaluation.

[0020] Furthermore, in this method, by fitting the first derivative values, a first derivative curve is obtained, revealing the velocity characteristics of the change in the cross-sectional area of the flow-through section. The first derivative curve is subjected to a second-order degradation to obtain the second derivative values, and based on this, a second derivative curve is fitted to deeply analyze the acceleration characteristics of the change in the cross-sectional area of the flow-through section. After obtaining the second derivative curve, taking the third discrete point coordinates corresponding to the center of the center line of the flow channel as the segmentation points, the second derivative curve is cleverly divided into two segments, namely the first change curve and the second change curve, simplifying the complexity of the problem and enabling independent analysis and evaluation of the first half and the second half of the flow channel respectively. Based on the discrete point coordinates of the first change curve and the discrete point coordinates of the second change curve, the first absolute value integral T 1 and the second absolute value integral T 2 are respectively calculated, reflecting the cumulative effects of the fluid flow changes in the first half and the second half of the flow channel, improving the accuracy and comprehensiveness of the evaluation, and contributing to improving the working efficiency and service life of the pump and reducing the operation cost and maintenance cost.

[0021] Furthermore, by comprehensively considering the number of extreme points E x , the first absolute value integral T 1 and the second absolute value integral T 2 , a comprehensive evaluation of the performance of the pump impeller passage is achieved. By comparing with the preset number of extreme values and integral range, the cavitation performance and hydraulic performance of the pump impeller passage can be accurately judged. When both the number of extreme points and the first absolute value integral are within the optimal range, it indicates that the cavitation performance of the pump impeller passage is good; and the smaller the second absolute value integral, the better the hydraulic performance. If the number of extreme points exceeds the preset range, it is directly determined that both the hydraulic performance and cavitation performance of the pump impeller passage are poor, improving the accuracy and objectivity of the evaluation, and contributing to enhancing the overall performance and operating efficiency of the pump.

[0022] The present invention proposes a quantitative evaluation system for the flow-through cross-section of a pump impeller passage. In this system, the first processing unit can accurately calculate the flow-through cross-sectional area of the passage through parametric processing, providing a reliable data basis for subsequent analysis. The fitting unit then fits the change curve of the flow-through cross-sectional area using these data, intuitively showing the dynamic change of the fluid flow cross-section in the passage. The second processing unit further performs degradation statistics and line division processing on the change curve of the flow-through cross-sectional area to obtain the first change curve and the second change curve, and calculates the discrete point coordinates and integral values related to the first-order and second-order derivatives based on this. These results provide strong support for in-depth understanding of the fluid flow characteristics in the passage. The third processing unit then calculates the first absolute value integral T 1 and the second absolute value integral T 2 respectively based on the first change curve and the second change curve, reflecting the smoothness and uniformity of the fluid flow in the passage. The evaluation unit then comprehensively considers parameters such as the number of extreme points E x , the first absolute value integral T 1 and the second absolute value integral T 2 to conduct a comprehensive performance evaluation of the pump impeller passage and obtain accurate evaluation results. Finally, the output unit clearly presents the evaluation results. This system integrates multiple functional units to form an efficient, accurate and comprehensive evaluation process, improving the accuracy and comprehensiveness of the performance evaluation of the pump impeller passage. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic flow chart of a quantitative evaluation method for the flow-through cross-section of a pump impeller passage proposed by the invention; Figure 2 is a schematic diagram of the passage and the center control points of the flow path in a quantitative evaluation method for the flow-through cross-section of a pump impeller passage proposed by the present invention; Figure 3Schematic diagram of the calculation method for the cross-sectional area of the flow passage of a pump impeller proposed by the present invention; Figure 4 Schematic diagram of the sectional points of the flow section in the quantitative evaluation method for the cross-sectional area of the flow passage of a pump impeller proposed by the present invention; Figure 5 Schematic diagram of the cross-sectional area of the flow passage in the embodiment proposed by the present invention; Figure 6 Schematic diagram of the curve of the change in the cross-sectional area of the flow passage in the embodiment proposed by the present invention; Figure 7 First derivative curve in the embodiment proposed by the present invention; Figure 8 First change curve in the embodiment proposed by the present invention; Figure 9 Second change curve in the embodiment proposed by the present invention. Detailed implementation manners

[0024] In the following, only some exemplary embodiments are briefly described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary in nature rather than restrictive.

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0026] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0027] In the present invention, unless otherwise clearly specified or limited, the terms "installed", "connected", "connected to", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or a communication connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0029] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0030] See Figure 1 , the present invention provides a quantitative evaluation method for the flow cross-section of a pump impeller passage, including the following steps: After parameterizing the impeller passage to be evaluated, calculate the flow cross-sectional area of the passage; Specifically, parameterize the Bezier curve of the passage profile of the pump impeller passage to obtain the coordinates of the first control control points of the hub curve and the coordinates of the second control control points of the shroud curve, as Figure 2 shown; In this embodiment, the coordinates of the first control control points of the hub curve are p1, p2, p3, p4, p5 respectively, and the coordinates of the second control control points of the shroud curve are p6, p7, p8, p9, p10 Calculate the coordinates of the control points of the passage center line based on the coordinates of the first control control points and the coordinates of the second control control points; wherein, the coordinates of the control points of the passage center line are p11, p12, p13, p14, p15.

[0031] In this embodiment, the calculation process of calculating the coordinates of the control points of the passage center line based on the coordinates of the first control control points and the coordinates of the second control control points is as follows:

[0032]

[0033]

[0034]

[0035]

[0036] The center line of the flow channel is obtained by fitting based on the coordinates of the control points; The cross-sectional area of the flow-through is calculated based on a plurality of third control points selected on the center line of the flow channel.

[0037] Specifically, a plurality of points are arbitrarily selected on the center line of the flow channel and denoted as third control points; an inscribed circle with a radius of r is drawn with the third control point as the center O, the tangent point of the inscribed circle and the hub curve is marked as tangent point A, and the tangent point of the inscribed circle and the shroud curve is marked as tangent point B; The perpendicular distances between the center O and the tangent points A and B are equally divided to obtain equally divided points, that is, connect the tangent points A and B, draw a perpendicular line OD to AB through the center O and divide it into three equal parts, and the equally divided points are equally divided points C and equally divided point E, as Figure 3 shown; Obtain the equally divided point E, connect the three points of the equally divided point E, the tangent point A and the tangent point B with a fair curve to obtain an arc , and calculate the arc length and correct it, that is, the arc length is approximately equal to twice the radius r of the inscribed circle, then ≈2r.

[0038] Obtain the distance R from the center of the circle to the axis of the central hole of the impeller c , through the axial distance R c and the arc length calculate the cross-sectional area F of the flow-through p .

[0039] Through the axial distance R c and the arc length calculate the cross-sectional area F of the flow-through p The calculation process is as follows:

[0040] Among them, is the distance from the center of the circle to the axis of the central hole of the impeller, is the length of the arc.

[0041] Based on the cross-sectional area F of the flow-through p fit the cross-sectional area change curve; Specifically, obtain the percentage length of the center line of the flow channel; use the percentage length of the center line of the flow channel as the abscissa and the data value of the cross-sectional area F p to fit the coordinate points of the change curve, and mark the coordinate points of the change curve in the rectangular coordinate system to obtain the cross-sectional area change curve; Perform a first-order degradation statistics on the cross-sectional area change curve to obtain the number of extreme points E x , and then perform secondary degradation and line division in sequence to obtain the first change curve and the second change curve; Specifically, divide the cross-sectional area change curve into multiple equal segments. In this embodiment, it is divided into 200 equal segments, mark the endpoints of each segment after the multiple equal segments, and obtain the coordinate data of the endpoints to obtain the first discrete point coordinates, which are denoted as F k [x k , y k , 0 ≤ k ≤ 200; Perform a first-order degradation on two adjacent first discrete point coordinates to obtain the first derivative value, that is, calculate the first derivative of the cross-sectional area change curve using two adjacent first discrete points, calculate the first derivative value Slope1 at the first discrete point, and denote the second discrete point coordinates obtained after the first-order degradation of the first discrete point coordinates as F1 i [x i , y i , 0 ≤ i ≤ 199; Among them, the calculation process of the first derivative value Slope1 is:

[0042] In the formula, The ordinate of the first discrete point F k , is the ordinate of the discrete point adjacent to the first discrete point F k ; The abscissa of the first discrete point F k , is the abscissa of the discrete point adjacent to the first discrete point F k ;

[0043] Based on the first derivative value, count the number of extreme points E x , that is, when the positive and negative signs of two adjacent first derivative values are different, an extreme point appears. Count all the first derivative values to obtain the number of extreme points E x .

[0044] Fit the first derivative curve based on the first derivative value; Perform a secondary degradation on the first derivative curve to obtain the second derivative value, and denote the third discrete point coordinates obtained after the secondary degradation of the second discrete point coordinates as F2 j[x j , y j ; that is, the second derivative of the first derivative curve is calculated using two adjacent second discrete points, the second derivative value Slope2 at the second discrete point is calculated, and the coordinate of the third discrete point obtained after the quadratic degradation of the first discrete point coordinate is denoted as F2 j [x j , y j , 0 ≤ j ≤ 198; Among them, the calculation process of the second derivative value Slope2 is as follows:

[0045] In the formula, the ordinate of the second discrete point F1 i , is the ordinate of the discrete point adjacent to the second discrete point F1 i ; the abscissa of the second discrete point F1 i , is the abscissa of the discrete point adjacent to the second discrete point F1 i .

[0046] The second derivative curve is fitted based on the second derivative value; Taking the coordinate of the third discrete point corresponding to the center of the flow channel center line as the segmentation point, the second derivative curve is divided into two segments, as Figure 4 shown, where one segment is marked as the first change curve f 2a , and the other segment is marked as the second change curve f 2b . The segmentation of the second derivative curve is to take into account the hydraulic performance and cavitation performance. Then, the coordinate of the third discrete point corresponding to the center of the flow channel center line is used as the segmentation point to divide the second derivative curve into two segments. The front segment of the second derivative curve is the first change curve f 2a , and the rear segment of the second derivative curve is the second change curve f 2b . Moreover, the coordinate of the third discrete point in the first change curve f 2a is marked as the coordinate of the first change curve discrete point F2 aj [x aj , y aj ; The coordinate of the third discrete point in the second change curve f 2a is marked as the coordinate of the second change curve discrete point F2 bj [x bj , y bj .

[0047] The first absolute integral T 1 and the second absolute integral T 2 are calculated based on the first change curve and the second change curve; Specifically, the first absolute integral T is calculated based on the discrete point coordinates of the first change curve and the discrete point coordinates of the second change curve respectively. 1 and the second absolute integral T 2 .

[0048] Among them, the calculation process of calculating the first absolute integral T based on the discrete point coordinates of the first change curve 1 is as follows:

[0049] Among them, is the ordinate value of the discrete point coordinate F2 of the first change curve aj , is the ordinate value of the coordinate point adjacent to the discrete point coordinate F2 of the first change curve aj , is the abscissa value of the discrete point coordinate F2 of the first change curve aj , is the abscissa value of the coordinate point adjacent to the discrete point coordinate F2 of the first change curve aj ; The calculation process of calculating the second absolute integral T based on the discrete point coordinates of the second change curve 2 is as follows;

[0050] Among them, is the ordinate value of the discrete point coordinate F2 of the first change curve bj , is the ordinate value of the coordinate point adjacent to the discrete point coordinate F2 of the first change curve bj , is the abscissa value of the discrete point coordinate F2 of the first change curve bj , is the abscissa value of the coordinate point adjacent to the discrete point coordinate F2 of the first change curve bj .

[0051] Based on the number of extreme points E x , the first absolute integral T 1 and the second absolute integral T 2 perform a performance evaluation on the cross-section of the overflow to obtain an evaluation result.

[0052] Specifically, the number of extreme points E x is respectively compared with a preset first preset extreme point value and a second preset extreme point value. Among them, the first preset extreme point value is 1, and the second preset extreme point value is 2, that is, the number of extreme points E x is respectively compared with 1 and 2; The first absolute integral T 1Compare with a preset first preset integral range and a preset second preset integral range respectively; wherein, the first preset integral range is [0.2, 0.8], and the second preset integral range is [0.5, 1.3], that is, the first absolute value integral T 1 Compare with [0.2, 0.8] and [0.5, 1.3] respectively; The second absolute value integral T 2 Compare with a preset third preset integral range and a preset fourth preset integral range respectively; wherein, the third preset integral range is [0, 0.9], and the fourth preset integral range is [0, 1.9], that is, the second absolute value integral T 2 Compare with [0, 0.9] and [0, 1.9] respectively; When the number of extreme points E x ≤1, and the first absolute value integral T 1 is within [0.2, 0.8], it is evaluated that the cavitation performance of the pump impeller passage is average, and when the second absolute value integral T 2 is within [0, 0.9], the smaller the second absolute value integral T 2 , the better the evaluated hydraulic performance of the pump impeller passage; When the number of extreme points E x = 2, and the first absolute value integral T 1 is within [0.5, 1.3], it is evaluated that the cavitation performance of the pump impeller passage is good, and when the second absolute value integral T 2 is within [0, 1.9], the smaller the second absolute value integral T 2 , the better the evaluated hydraulic performance of the pump impeller passage; When the number of extreme points E x > 2, it is evaluated that both the hydraulic performance and cavitation performance of the pump impeller passage are poor.

[0053] In this embodiment, the performance evaluation of the flow-through section by the number of extreme points E x , the first absolute value integral T 1 and the second absolute value integral T 2 is analyzed based on the vortex dynamics theory. On the premise of satisfying fluid continuity, the momentum equation can be expressed as:

[0054] In the formula, τ represents the spatial variable, f represents the volume force, and V represents the control volume.

[0055] In the vortex dynamics theory, the Reynolds transport equation can be expressed as:

[0056] Wherein, K represents the total kinetic energy in the control volume, S represents the variable area of the control volume boundary, and U bn represents the moving speed of the control volume boundary, and P and D respectively represent the work done by the control volume deformation and the dissipation work caused by entropy increase dissipation. Since the body force can be ignored in the absolute coordinate system, the shaft power transferred to the fluid when using the impeller work is used to represent the product of the fluid velocity and the surface stress, and we can get:

[0057] Wherein, S W represents the area W of the flow-through cross-section, and K represents the total kinetic energy. After ignoring the viscous force and the inertial force, the total pressure flow integral P u satisfies the following equation:

[0058] Based on the above principle analysis, it can be seen that the change in the area of the flow-through cross-section reflects to a certain extent the change in the fluid pressure during the flow process, and essentially reflects the change in energy in the flow channel. Therefore, ensuring a smooth transition in the change of the area of the flow-through cross-section can ensure a smoother energy transfer in the flow channel and reduce hydraulic losses; at the position near the blade inlet in the front section of the flow channel, appropriately increasing the area of the flow-through cross-section, that is, increasing the pressure level at that place, can effectively reduce the occurrence of cavitation at the blade inlet.

[0059] The above method will be further explained below with reference to embodiments: Obtain a pump impeller flow channel model for evaluation, parameterize the flow channel profile using Bezier curves, and obtain the control point coordinates of the hub curve as p1[0, 10.5], p2[0.86, 10.5], p3[43.24, 10.52], p4[43.24, 55], p5[43.24, 87], and the coordinates of the shroud curve as p6[0, 37], p7[23.19, 39.77], p8[23.67, 39.83], p9[25.18, 49.23], p10[31.24, 87]. Calculate the control points of the center line of the flow channel, and obtain its control point coordinates as p11[0,23.75], p12[12.025, 25.135], p13[33.455, 20.175], p14[34.21, 52.115], p15[37.24,87].

[0060] After obtaining the control point coordinates of the flow channel profile, randomly select multiple points on the center line of the flow channel, denoted as the third control points; draw an inscribed circle with a radius of r with the third control point as the center, equally divide the vertical distance between the center and the tangent points A and B to obtain equally divided points; obtain the arc length between the equally divided point E, the tangent point A and the tangent point B, and obtain the arc length ; Based on obtaining the distance R from the center of the circle (the axis of the central hole of the impeller) c and the length of the arc calculate the cross-sectional area F of the flow passage p , as Figure 5 shown, based on the cross-sectional area F of the flow passage p fit the cross-sectional area change curve, as Figure 6 shown; Perform a first-level degradation statistics on the cross-sectional area change curve of the flow passage to obtain the number of extreme points E x = 2, and then perform secondary degradation and line division processing in sequence to obtain the first change curve and the second change curve, as Figures 7 to 9 shown, calculate the first absolute value integral T 1 and the second absolute value integral T 2 based on the first change curve and the second change curve respectively, T 1 = 1.28318, T 2 = 1.87611; Based on the number of extreme points E x = 2, the first absolute value integral T 1 = 1.28318 and the second absolute value integral T 2 = 1.87611, evaluate the performance of the flow passage of the impeller. It is evaluated that the hydraulic performance of the impeller flow passage model is good and the cavitation performance is good. Subsequent optimization can be carried out for optimizing the T 2 value to make it smaller so as to improve the hydraulic performance of the flow passage.

[0061] The present invention proposes a quantitative evaluation system for the cross-sectional area of the impeller flow passage of a pump to implement the above method, including a first processing unit, a fitting unit, a second processing unit, a third processing unit, an evaluation unit and an output unit. Among them, the first processing unit is communicatively connected to the fitting unit, the fitting unit is communicatively connected to the second processing unit, the second processing unit is communicatively connected to the third processing unit and the evaluation unit, the third processing unit is communicatively connected to the evaluation unit, and the evaluation unit is communicatively connected to the output unit; The first processing unit is used to calculate the cross-sectional area of the flow passage after parameterizing the impeller flow passage to be evaluated; The fitting unit is used to fit the cross-sectional area change curve based on the cross-sectional area of the flow passage; The second processing unit is used to perform statistics on the cross-sectional area change curve of the flow passage to obtain the number of extreme points E x , and perform discrete line division processing on the cross-sectional area change curve of the flow passage to obtain the first change curve and the second change curve; The third processing unit is used to calculate the first absolute value integral T 1and the second absolute value integral T 2 ; An evaluation unit for performing performance evaluation on the cross-section of overcurrent based on the number of extreme points E x , the first absolute value integral T 1 and the second absolute value integral T 2 to obtain an evaluation result; An output unit for outputting the evaluation result.

[0062] The foregoing has shown and described the basic principles, main features and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be construed as limiting the claimed rights.

[0063] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A method for quantitatively evaluating the flow section of a pump impeller flow passage, characterized in that: The following steps are involved: After parameterizing the pump impeller flow passage to be evaluated, the flow cross-sectional area is calculated; Obtaining a flow cross-sectional area variation curve based on the flow cross-sectional area fitting; The number of extreme value points E is obtained by performing a degradation statistics on the cross-sectional area change curve. x After that, secondary degradation and line splitting are performed in sequence to obtain a first change curve and a second change curve; Based on the first change curve and the second change curve, respectively calculate a first absolute value integral T1 and a second absolute value integral T2; Based on the number of extreme points E x The first absolute value integral T1 and the second absolute value integral T2 are used to perform a performance evaluation on the flow section to obtain an evaluation result of the pump impeller flow channel.

2. A method for quantitatively evaluating the flow cross section of a pump impeller flow passage according to claim 1, characterized in that: The flow cross-sectional area is calculated based on parameterization of the impeller flow passage to be evaluated, including: Parameterizing the flow channel profile of the impeller flow channel by a Bezier curve to obtain the coordinates of the first control point of the hub curve and the coordinates of the second control point of the shroud curve; Calculate the control point coordinates of the flow channel centerline based on the first control point coordinates and the second control point coordinates; The flow channel centerline is obtained based on the coordinate fitting of the control points; The flow cross-sectional area is calculated based on a plurality of third control points selected on the centerline of the flow channel.

3. A method for quantitatively evaluating the flow cross section of a pump impeller flow passage according to claim 2, characterized in that: The flow cross-sectional area is calculated based on a plurality of third control points selected on the center line of the flow channel, including: Arbitrarily select multiple points on the center line of the flow channel and record them as third control points; Draw an inscribed circle with a radius of r with the third control point as the center, and mark the tangent point between the inscribed circle and the hub curve as tangent point A, and mark the tangent point between the inscribed circle and the shroud curve as tangent point B; Divide the vertical distance between the center of the circle and the tangent points A and B equally to obtain the equal division points; Get the arc length between the equal division point E, the tangent point A and the tangent point B to get the arc length ; Based on the obtained center of the circle, the axial distance R of the impeller center hole c and the arc length The cross-sectional area F is calculated as follows: p .

4. A method for quantitatively evaluating the flow cross section of a pump impeller flow passage according to claim 3, characterized in that: The center of the circle refers to the axial distance R of the impeller center hole. c and the arc length The cross-sectional area F is calculated as follows: p The calculation process is: in, The center of the circle refers to the axial distance of the impeller center hole. is the length of the arc.

5. A method for quantitatively evaluating the flow cross section of a pump impeller flow passage according to claim 2, characterized in that: The flow cross-sectional area variation curve is obtained based on the flow cross-sectional area fitting, including: Obtaining the percentage length of the center line of the flow channel; Constructing a change curve coordinate point based on the percentage length and the flow cross-sectional area; The flow cross-sectional area change curve is obtained by fitting the change curve coordinate points in a rectangular coordinate system.

6. A method for quantitatively evaluating the flow cross section of a pump impeller flow passage according to claim 1, characterized in that: The number of extreme value points E is obtained by performing a degradation statistics on the cross-sectional area change curve. x ,include: The cross-sectional area variation curve is divided into multiple equal sections, the endpoints of each section after the multiple equal sections are marked, and the coordinate data of the endpoints are obtained to obtain the coordinates of the first discrete point, and the coordinates of the first discrete point are marked as F k [x k , y k ], k ≥ 0; Based on the coordinates of two adjacent first discrete points, a first-order derivative value is obtained by performing a degradation, and the coordinates of the second discrete point obtained after the first discrete point coordinates are degraded once are recorded as F1 i [x i , y i ]; The number of extreme points E is obtained based on the first-order derivative statistics x .

7. A method for quantitatively evaluating the flow cross section of a pump impeller flow passage according to claim 6, characterized in that: The performing of secondary degradation and line splitting to obtain a first change curve and a second change curve includes: Obtaining a first-order derivative curve based on the first-order derivative value fitting; The first-order derivative curve is further degraded twice to obtain a second-order derivative value, and the coordinates of the third discrete point obtained after the second discrete point coordinates are degraded twice are recorded as F2 j [x j , y j ]; Obtaining a second-order derivative curve based on the second-order derivative value fitting; The coordinates of the third discrete point corresponding to the center of the flow channel midline are used as segmentation points to divide the second-order derivative curve into two segments, one of which is marked as the first variation curve f 2a , and the other section is marked as the second variation curve f 2b ; Then the first variation curve f 2a The third discrete point coordinate in the first variation curve is marked as the discrete point coordinate F2 a j [x aj , y aj ]; The second variation curve f 2a The third discrete point coordinate in the second variation curve is marked as the discrete point coordinate F2 bj [x bj , y bj ]; The first absolute value integral T1 and the second absolute value integral T2 are calculated based on the discrete point coordinates of the first change curve and the discrete point coordinates of the second change curve, respectively.

8. A method for quantitatively evaluating the flow cross section of a pump impeller flow passage according to claim 7, characterized in that: The calculation process of obtaining the first absolute value integral T1 based on the discrete points of the first change curve is: in, F2 is the coordinate of the discrete point of the first change curve aj The vertical coordinate value of The coordinates of the discrete points F2 of the first variation curve aj The ordinate values ​​of adjacent coordinate points, F2 is the coordinate of the discrete point of the first change curve aj The horizontal axis value of The coordinates of the discrete points F2 of the first variation curve aj The horizontal coordinate values ​​of adjacent coordinate points; The calculation process of obtaining the second absolute value integral T2 based on the coordinates of the discrete points of the second change curve is as follows: in, F2 is the coordinate of the discrete point of the first change curve bj The vertical coordinate value of The coordinates of the discrete points F2 of the first variation curve bj The ordinate values ​​of adjacent coordinate points, F2 is the coordinate of the discrete point of the first change curve bj The horizontal axis value of The coordinates of the discrete points F2 of the first variation curve bj The horizontal coordinate values ​​of adjacent coordinate points.

9. A method for quantitatively evaluating the flow cross section of a pump impeller flow passage according to claim 1, characterized in that: Based on the number of extreme points E x , the first absolute value integral T1 and the second absolute value integral T2 perform performance evaluation on the current flow section to obtain an evaluation result, including: The number of extreme points E x Compare the first absolute value integral T1 with the preset first preset integral range and the preset second preset integral range respectively; compare the second absolute value integral T2 with the preset third preset integral range and the preset fourth preset integral range respectively; When the number of extreme points E x When the first absolute value integral T1 does not exceed the first preset extreme value, and the first absolute value integral T1 is within the first preset integral range, it is evaluated that the cavitation performance of the pump impeller flow channel is average, and when the second absolute value integral T2 is within the third preset integral range, the smaller the second absolute value integral T2 is, the better the hydraulic performance of the pump impeller flow channel is; When the number of extreme points E x When the second absolute value integral T1 is equal to the second preset extreme value, and the first absolute value integral T1 is within the second preset integral range, it is evaluated that the cavitation performance of the pump impeller flow channel is good, and when the second absolute value integral T2 is within the fourth preset integral range, the smaller the second absolute value integral T2 is, the better the hydraulic performance of the pump impeller flow channel is; When the number of extreme points E x When the second preset extreme value is exceeded, it is evaluated that the hydraulic performance and cavitation performance of the pump impeller flow channel are both poor.

10. A quantitative evaluation system for flow cross section of a pump impeller flow passage, used to implement the evaluation method according to any one of claims 1 to 9, characterized in that: include: A first processing unit is used to calculate the flow cross-sectional area based on parameterization of the pump impeller flow passage to be evaluated; A fitting unit, used for fitting the flow cross-sectional area to obtain a flow cross-sectional area variation curve based on the flow cross-sectional area; The second processing unit is used to perform a degradation statistics on the cross-sectional area change curve to obtain the number of extreme value points E. x After that, secondary degradation and line splitting are performed in sequence to obtain a first change curve and a second change curve; A third processing unit, configured to calculate a first absolute value integral T1 and a second absolute value integral T2 based on the first change curve and the second change curve respectively; An evaluation unit, for evaluating the number of extreme value points E based on the x , the first absolute value integral T1 and the second absolute value integral T2 are used to evaluate the performance of the flow section to obtain an evaluation result of the pump impeller flow channel; The output unit is used to output the evaluation result of the pump impeller flow passage.

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