Reverse problem load loading method for optimizing wear performance of centrifugal pumps with different specific speeds

Abstract

The invention discloses a reverse problem load loading method for optimizing the wear performance of centrifugal pumps with different specific speeds, and can effectively solve the problems that the traditional centrifugal pump optimization design mainly depends on experience and repeated trial calculation, and is low in efficiency and poor in accuracy. Aiming at the wear performance of the centrifugal pump, based on an inverse problem design method, the influence of different blade load loading modes on the wear characteristics of the centrifugal pumps with different specific speeds is determined, and an optimized load loading scheme for improving the wear performance of the centrifugal pumps with different specific speeds is obtained. And analyzing different control point distribution rules of blade load loading in the different-specific-speed centrifugal pump wear performance optimization scheme, obtaining a relational expression between each control point and the specific speed, and realizing an inverse problem load loading method for different-specific-speed centrifugal pump wear performance optimization. The method is scientific and reasonable in design and easy to operate, the relational expression is reasonable and reliable, the efficient, rapid and convenient optimization method can be provided for optimization of the wear characteristics of the centrifugal pump impeller, and remarkable economic and social benefits are achieved.

Description

Technical Field

[0001] The invention relates to a centrifugal pump, in particular to an inverse problem load loading method for optimizing the wear performance of centrifugal pumps with different specific speeds based on a three-dimensional inverse problem design method. Background Art

[0002] Centrifugal pumps are widely used in pumping stations along rivers due to their advantages such as easy maintenance and high head. The wear of centrifugal pump flow components caused by river water seriously affects the safe and efficient operation of the pumping station. Therefore, it is necessary to optimize the design of centrifugal pumps. It mainly relies on the experience of designers to repeatedly carry out the optimization, which not only requires a lot of time and energy, but also the design results cannot be predicted. Inverse problem is a fast and effective optimization method. Among them, the blade load loading method is the key step of inverse problem design, but the loading method will affect the wear characteristics of different centrifugal pumps. Therefore, according to the inverse problem design method, it is necessary to study the influence of different blade load loading methods on the wear characteristics of centrifugal pump impellers during inverse problem design, and analyze the relationship between blade load loading methods and the change of centrifugal pump specific speed. Under the condition of ensuring the head and efficiency of centrifugal pumps with different specific speeds, the centrifugal pump impeller with better wear performance is obtained, revealing the relationship between the three-dimensional inverse problem optimization design results and the specific speed of the centrifugal pump. It provides technical support for the optimization of centrifugal pump impeller wear characteristics and the optimization application of three-dimensional inverse problem design in the field of wear characteristics of solid-liquid two-phase flow in centrifugal pumps, but there has been no public report so far. Summary of the invention

[0003] In view of the above situation, in order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide an inverse problem load loading method for optimizing the wear performance of centrifugal pumps with different specific speeds, which can effectively solve the problem that the traditional centrifugal pump optimization design mainly relies on experience and repeated trial calculations, and has low efficiency and poor accuracy.

[0004] The technical solution solved by the present invention is an inverse problem load loading method for optimizing the wear performance of centrifugal pumps with different specific speeds. The method is characterized in that, based on the inverse problem design method, the influence of different blade load loading methods on the wear characteristics of centrifugal pumps with different specific speeds is determined for the wear performance of the centrifugal pump, and an optimized load loading scheme for improving the wear performance of centrifugal pumps with different specific speeds is obtained. The distribution law of different control points of blade load loading in the wear performance optimization scheme of centrifugal pumps with different specific speeds is analyzed, and the relationship between each control point and the specific speed is obtained, thereby realizing the inverse problem load loading method for optimizing the wear performance of centrifugal pumps with different specific speeds.

[0005] The method of the invention is scientifically and reasonably designed, easy to operate, and has a reasonable and reliable relationship. It can provide an efficient, fast and convenient optimization method for optimizing the wear characteristics of centrifugal pump impellers, and has significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 The "three-stage" load distribution diagram on the blade streamline of the present invention (wherein the ordinate is the blade load and the abscissa is the axial streamline position m);

[0007] Figure 2 It is a discrete diagram of load control points of the optimal solutions of various specific speed centrifugal pumps of the present invention;

[0008] Figure 3 A comparison diagram of the fitting equations of each control point of the load of the present invention and the discrete values ​​of each control point of the load of each optimal solution;

[0009] Figure 4 For the present invention s =110 Blade load loading method diagram;

[0010] Figure 5 For the present invention s =110 blade shape diagram obtained by loading scheme;

[0011] Figure 6 Wear distribution diagram of the working and back surfaces of the blades of the original centrifugal pump and the optimized centrifugal pump. DETAILED DESCRIPTION

[0012] The specific implementation modes of the present invention are described in detail below in combination with embodiments and specific situations.

[0013] The present invention can be implemented in the following specific ways:

[0014] An inverse problem load loading method for optimizing the wear performance of centrifugal pumps with different specific speeds is provided by the following steps in specific implementation:

[0015] 1. Select the specific speed n commonly used in riverside pumping stations s =90-205 centrifugal pumps of the same type are optimized, respectively n s1 =90, n s2 =110, n s3 =130, n s4 =150, n s5 =205 five kinds;

[0016] 2. The inverse problem design method is used to change the blade shape by controlling the pressure load distribution on the blade. The load on the blade streamline adopts a "three-stage" load distribution, which consists of three parts: the front loading point NC, the rear loading point ND, and the loading slope Slope. The horizontal and vertical coordinates represent the relative position and load on the axial streamline. The 0 in the relative position represents the blade inlet position, and 1 represents the blade outlet position. The front and rear cover streamlines are the intersection lines of the front and rear cover and the blade, respectively. The solid line represents the front cover streamline, and the dotted line represents the rear cover streamline (see Figure 1 );

[0017] 3. Without changing the axial flow channel of each centrifugal pump impeller, three inverse problem design optimization schemes are designed for the five centrifugal pumps with different specific speeds given in step 1, and impellers with different blade shapes are obtained. The load distribution of each specific speed optimization scheme is given in the following table:

[0018]

[0019] 4. Each scheme uses the wear performance of the centrifugal pump impeller as the standard to select the optimal blade load distribution scheme, specifically: n s1 =90 Centrifugal Pump Solution 2, n s2 =110 Centrifugal Pump Solution 3, n s3 =130 Centrifugal Pump Solution 3, n s4 =150 Centrifugal Pump Solution 1, n s5 =205 Scheme 3 of the centrifugal pump. In order to more intuitively observe the relationship between the load control point and the specific speed, the load control point discrete diagram of the optimal scheme of each specific speed centrifugal pump is drawn (see Figure 2 );

[0020] 5. Based on the relationship between each load control point and the specific speed, regression fitting analysis is performed on the parameters of each optimal solution to establish NC, ND, Slope and n s The equation between is:

[0021] according to Figure 2 The quadratic polynomial is initially chosen as its mathematical formula:

[0022]

[0023] Where, ns is the specific speed; a, b, c are the coefficients of the quadratic polynomial; y is the value of the load control point;

[0024] Substitute the control point value parameters into formula (1), and use the least squares method to determine the values ​​of coefficients a, b, and c. Substitute the values ​​of a, b, and c into formula (1) to obtain the final control equation of each load control point:

[0025]

[0026] In the formula, NC s ND s 、Slope s NC is the upper cover control point; h ND h 、Slope h is the lower cover control point, n s is the specific speed.

[0027] Comparison of the fitting equations of each control point of the verification load and the discrete values ​​of each control point of each optimal solution load (see Figure 3 ), when the discrete load control points are distributed near the control equation, it is proved that the control equation is reasonable and reliable, thus realizing the inverse problem load loading for the wear performance optimization of centrifugal pumps with different specific speeds.

[0028] The invention is scientifically and rationally designed, easy to operate, stable and reliable, and has been proven to be very effective. The relevant information is as follows:

[0029] Select Q = 775m 3 / h, H = 60m, n = 1450r / min centrifugal pump is the optimization object, and the calculation condition is based on the Yellow River water after sedimentation in the sedimentation tank as the conveying medium, and its solid volume fraction α s =0.188%, particle size d s =25μm, the density of solid particles is ρ s =2650kg / m 3 The rated flow condition is selected to perform steady-state calculation of solid-liquid two-phase flow on the original centrifugal pump and the water pump after inverse problem design. The centrifugal pump after inverse problem design is different from the original centrifugal pump only in the impeller, and other flow-passing parts remain unchanged, specifically:

[0030] The known calculation formula for a centrifugal pump is:

[0031]

[0032] Where n s is the specific speed; Q is the flow rate; H is the head; n is the speed;

[0033] Substituting the centrifugal pump parameters into equation (3), we get equation (4), as follows:

[0034]

[0035] Get the specific speed of the centrifugal pump as n s =110.

[0036] n s =110 is substituted into formula (2) to obtain the specific parameters of each load control point. The calculation results are shown in formula 3. Among them, the upper cover load control point is NC s =0.173, ND s =0.828, Slope s =-0.259; the load control point of the lower cover is NC h =0.195, ND h =0.814, Slope h = 0.235. The specific value of the load control point is input into the three-dimensional inverse problem design software "Turbodesign" to obtain the specific loading method as follows Figure 4 In the figure, the horizontal axis is the relative position of the blade axial streamline, and the vertical axis is the blade load value.

[0037]

[0038] according to Figure 4 The load point value determines the blade load loading method, and the blade thickness is further given in the design software "Turbodesign". The original centrifugal pump head, flow rate and other design parameters finally get the corresponding blades as shown in the figure. Figure 5 As shown in the figure, the blade model is used to replace the original pump blade to obtain the optimized centrifugal pump.

[0039] The solid-liquid two-phase flow steady state calculation is performed on the original centrifugal pump and the centrifugal pump obtained by the load loading scheme. The calculation shows that: s =110 The maximum wear rate of the original centrifugal pump is 8.28×10 -7 kg / (m 2 ·s), the maximum wear rate of the optimized solution is 7.42×10 -7 kg / (m 2 ·s), a year-on-year decrease of 9.29%.

[0040] The influence of the optimization scheme on the blade wear performance is further analyzed. Figure 6 The wear distribution of the blade working surface and back surface of the original centrifugal pump and the optimized centrifugal pump is given. Figure 6 It can be seen that compared with the original centrifugal pump, the severe wear area on the blades of the optimal centrifugal pump is significantly reduced, a large number of strip-shaped severe wear areas disappear, and the wear performance of the blades is significantly improved.

[0041] This proves the reliability of the established load control point equations, and can provide an accurate, efficient and convenient blade load loading method for the inverse problem design optimization of centrifugal pump wear performance. Compared with the traditional centrifugal pump optimization scheme, this method can not only save a lot of optimization time, but also greatly reduce the workload of designers during optimization design, improve work efficiency, and have good economic benefits.

[0042] The present invention also calculates the inverse problem optimization design of other specific speed centrifugal pumps, and obtains optimization solutions with good wear performance, which will not be described here one by one.

[0043] The present invention provides an inverse problem load loading method for optimizing the wear performance of centrifugal pumps with different specific speeds, which can effectively solve the problem that the optimization design of centrifugal pumps mainly relies on the experience of designers to repeatedly perform the optimization design, which not only requires a lot of time and energy, but also the design results are unpredictable. For the optimization of the wear performance of centrifugal pumps, based on the inverse problem design method, the influence of different blade load loading methods on the wear characteristics of centrifugal pumps with different specific speeds is determined, and the optimal load loading scheme for improving the wear performance of centrifugal pumps with different specific speeds is obtained. The distribution law of different control points of blade load loading of the optimal scheme for the wear performance of centrifugal pumps with different specific speeds is analyzed, and the relationship between each control point and the specific speed is obtained. An inverse problem design load loading method that can improve the wear performance of centrifugal pumps with different specific speeds is established. The obtained relationship is reasonable and reliable, and can provide an efficient, fast and convenient optimization method for optimizing the wear characteristics of centrifugal pump impellers.

[0044] The present invention proposes an inverse problem design optimization formula applicable to centrifugal pumps of various specific speeds. By distributing the pressure load on the blade in three stages, a relationship between the load control point and the specific speed is established, and the load distribution at different positions on the blade is changed to achieve changes in the blade shape and performance. The centrifugal pump inverse problem optimization model proposed by the present invention can shorten the optimization cycle and has good economic and social benefits.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical method of the present invention, rather than to limit the protection scope of the present invention. Although the invention is described in detail using better embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents, and equivalent embodiments or changes that do not deviate from the technical solution of the present invention should be within the protection scope of the present invention.

Claims

1. An inverse problem loading method for optimizing the wear performance of centrifugal pumps with different specific speeds, characterized in that: Aiming at the wear performance of centrifugal pumps, based on the inverse problem design method, the influence of different blade load loading methods on the wear characteristics of centrifugal pumps with different specific speeds is determined, and the optimized load loading scheme for improving the wear performance of centrifugal pumps with different specific speeds is obtained. The distribution law of different control points of blade load loading in the wear performance optimization scheme of centrifugal pumps with different specific speeds is analyzed, and the relationship between each control point and the specific speed is obtained, thus realizing the inverse problem load loading method for optimizing the wear performance of centrifugal pumps with different specific speeds.

2. An inverse problem load loading method for optimizing the wear performance of centrifugal pumps with different specific speeds, characterized in that: Given by the following steps: (1) Select the specific speed n commonly used in riverside pumping stations s =90-205 centrifugal pumps of the same type are optimized, respectively n s1 =90, n s2 =110, n s3 =130, n s4 =150, n s5 =205 five kinds; (2) The inverse problem design method is used to change the blade shape by controlling the pressure load distribution on the blade. The load on the blade streamline adopts a "three-stage" load distribution, which consists of three parts: the front loading point NC, the rear loading point ND, and the loading slope Slope. The horizontal and vertical coordinates represent the relative position and load on the axial streamline respectively. The 0 in the relative position represents the blade inlet position, and 1 represents the blade outlet position. The front and rear cover streamlines are the intersection lines of the front and rear cover and the blade respectively. The solid line represents the front cover streamline, and the dotted line represents the rear cover streamline. (3) Under the premise of not changing the axial flow channel of each centrifugal pump impeller, three inverse problem design optimization schemes are designed for the five centrifugal pumps with different specific speeds given in step (1), and impellers with different blade shapes are obtained. The load distribution of each specific speed optimization scheme is given in the following table: (4) Each scheme uses the wear performance of the centrifugal pump impeller as the standard to select the optimal blade load distribution scheme, specifically: n s1 =90 Centrifugal Pump Solution 2, n s2 =110 Centrifugal Pump Solution 3, n s3 =130 Centrifugal Pump Solution 3, n s4 =150 Centrifugal Pump Solution 1, n s5 =205 Scheme 3 of the centrifugal pump, in order to more intuitively observe the relationship between the load control point and the specific speed, the load control point discrete diagram of the optimal scheme of each specific speed centrifugal pump is drawn; (5) Based on the relationship between each load control point and the specific speed, regression fitting analysis is performed on the parameters of each optimal solution to establish NC, ND, Slope and n s The equation between is: According to Figure 2, a quadratic polynomial is initially selected as its mathematical formula: Where, ns is the specific speed; a, b, c are the coefficients of the quadratic polynomial; y is the value of the load control point; Substitute the control point value parameters into formula (1), and use the least squares method to determine the values ​​of coefficients a, b, and c. Substitute the values ​​of a, b, and c into formula (1) to obtain the final control equation of each load control point: In the formula, NC s ND s 、Slope s NC is the upper cover control point; h ND h 、Slope h is the lower cover control point, n s is the specific speed; Verify the comparison between the fitting equations of each load control point and the discrete values ​​of each load control point of each optimal solution. When the discrete load control points are distributed near the control equation, it is proved that the control equation is reasonable and reliable, thereby realizing the inverse problem load loading for optimizing the wear performance of centrifugal pumps with different specific speeds.

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