Guide vane structure optimization method, guide vane structure optimization system and guide vane structure

Abstract

The invention discloses a guide vane structure optimization method, a guide vane structure optimization system and a guide vane structure.The guide vane structure optimization method comprises the steps that a parameterized numerical model of a guide vane structure is established on the basis of a multi-physical-field coupling mechanism, namely, an equivalent stress calculation model of the guide vane structure is established on the basis of the coupling relation between physical fields; the equivalent stress is calculated through nonlinear coupling of fluid stress and centrifugal stress borne by the guide vane structure, quantitative correlation between key parameters of the guide vane structure and stress response is established, an explicit relation between the parameters of the guide vane structure and the equivalent stress is established according to the parameters of the guide vane structure influencing the stress borne by the guide vane structure, a multi-target constraint optimization equation is established, and the stress response of the guide vane structure is optimized. And based on the equivalent stress calculation model and the explicit relationship between the guide vane structure parameters and the equivalent stress, constructing a structure optimization equation of the guide vane structure, implementing sequential quadratic programming iterative optimization, and based on the structure optimization equation of the guide vane structure, performing iterative calculation by adopting an SQP algorithm until convergence conditions are met, thereby obtaining optimized values of the guide vane structure parameters.

Description

Technical Field

[0001] The present invention relates to the technical field of fluid machinery engineering, and more specifically, to a method for optimizing a guide vane structure, a system for optimizing a guide vane structure, and a guide vane structure. Background Art

[0002] The guide vane of a pump is a key component in a centrifugal pump and a mixed-flow pump, mainly used to guide the flow of fluid and achieve energy conversion.

[0003] In the design of the guide vane structure of a pump, traditional guide vane design methods mostly rely on empirical formulas or single physical field analysis, without fully considering the coupling effect of fluid dynamics and centrifugal force, resulting in inaccurate stress prediction; at the same time, traditional guide vane design methods lack an explicit correlation model for optimizing guide vane design parameters, making it difficult to quickly determine the optimal solution, with a long design cycle and prone to local overstress problems. Summary of the Invention

[0004] In order to solve the technical problems raised in the above background art, the purpose of the present invention is to provide a method for optimizing a guide vane structure, a system for optimizing a guide vane structure, and a guide vane structure, so as to propose a high-precision and rapid optimization design method for the guide vane structure in view of the problems of complex multi-physical field coupling analysis and low optimization efficiency in the design process of traditional pump guide vanes.

[0005] In order to achieve the above purpose, on the one hand, the present invention provides a method for optimizing a guide vane structure. In the technical solution of the present invention, the method for optimizing the guide vane structure specifically includes the following steps:

[0006] Step S1: Establish a parametric numerical model of the guide vane structure based on the multi-physical field coupling mechanism: establish an equivalent stress calculation model of the guide vane structure based on the coupling relationship between physical fields, and the equivalent stress is calculated through non-linear coupling of the fluid stress and centrifugal stress received by the guide vane structure;

[0007] Step S2: Establish a quantitative correlation between the key parameters of the guide vane structure and the stress response: according to the guide vane structure parameters that affect the stress received by the guide vane structure, establish an explicit relationship between the guide vane structure parameters and the equivalent stress;

[0008] Step S3: Construct a multi-objective constraint optimization equation: based on the equivalent stress calculation model and the explicit relationship between the guide vane structure parameters and the equivalent stress, construct a structural optimization equation of the guide vane structure;

[0009] Step S4: Implement sequential quadratic programming iterative optimization: based on the structural optimization equation of the guide vane structure, use the SQP algorithm for iterative calculation until the optimization values of the guide vane structure parameters are obtained when the convergence condition is met.

[0010] Further, in the step S1, the equivalent stress is calculated by non-linear coupling of the fluid stress and the centrifugal stress on the guide vane structure, and is specifically expressed as:

[0011] The equivalent stress is constructed by the non-linear superposition principle : ;

[0012] Wherein, represents the equivalent stress of the guide vane structure, represents the fluid stress of the guide vane structure, represents the centrifugal stress of the guide vane structure, , , represent the weight coefficients, represents the yield strength of the material of the guide vane structure.

[0013] Further, in the step S2, according to the guide vane structure parameters affecting the stress on the guide vane structure, specifically including:

[0014] The number of blades , the inlet angle , the blade thickness , the blade wrap angle and the diffusion angle ;

[0015] Wherein, an explicit relationship between the guide vane structure parameters and the equivalent stress is established, that is, a parameter mapping relationship, and is specifically expressed as:

[0016] .

[0017] Further, in the step S3, a structural optimization equation of the guide vane structure is constructed, specifically including:

[0018] Taking the equivalent stress as the objective function to be minimized, a multi-variable optimization equation including the guide vane structure parameters is established, and is specifically expressed as:

[0019] ;

[0020] Define the geometric constraint conditions and performance constraint conditions of the guide vane structure as the boundary conditions of the optimization equation.

[0021] Further, in the step S4, the convergence condition is expressed as that the change rate of the equivalent stress is less than 1%.

[0022] Further, in the technical solution of the present invention, the fluid stress is composed of an impact stress term and a pressure load term to quantify the mechanical action of the fluid on the guide vane structure. The fluid stress Specifically expressed as:

[0023] ;

[0024] Among them, 、 are expressed as empirical coefficients, is expressed as fluid density, is expressed as flow rate, is expressed as the area of a single flow channel, is expressed as the pressure difference across the flow channel, is expressed as the length of the guide vane.

[0025] Furthermore, in the technical solution of the present invention, the centrifugal stress is used to quantify the tensile effect of the rotational inertia force on the blade. The centrifugal stress is specifically expressed as:

[0026] ;

[0027] Among them, is expressed as the density of the guide vane structure material, is expressed as the angular velocity, is expressed as the guide vane diameter.

[0028] In the technical solution of the present invention, there is also a guide vane structure optimization system for implementing a guide vane structure optimization method as described above. The guide vane structure optimization system includes:

[0029] Parameter input module: used to receive guide vane structure parameters and operating conditions parameters;

[0030] Stress calculation module: performs equivalent stress calculation according to the equivalent stress calculation model;

[0031] Optimization algorithm module: calculates the optimized values of the guide vane structure parameters based on the SQP algorithm according to the structure optimization equation;

[0032] Structure output module: outputs the optimization result of the guide vane structure.

[0033] On the other hand, the present invention also provides a guide vane structure, and the guide vane structure is optimized and implemented according to a guide vane structure optimization system as described above.

[0034] Beneficial effects: In summary, the present invention provides a guide vane structure optimization method, a guide vane structure optimization system, and a guide vane structure. In the technical solution of the present invention, by establishing a non-linear coupling model of fluid stress and centrifugal stress, and based on the guide vane structure parameters affecting the stress on the guide vane structure, an explicit functional relationship between the guide vane structure parameters and the equivalent stress is established. At the same time, iterative calculations are carried out in combination with the SQP algorithm, realizing the efficient optimization of the guide vane parameters. Specifically, the present invention provides a high-precision and rapid optimization design method for the guide vane structure in view of the problems of complex multi-physical field coupling analysis and low optimization efficiency in the design process of the guide vane of traditional pumps, which can significantly improve the stress prediction accuracy and shorten the design and optimization cycle of the guide vane structure.

[0035] Other features and advantages of the present invention will be described in the following specification. Brief Description of the Drawings

[0036] In order to more clearly illustrate the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 It is a flowchart of a guide vane structure optimization method according to an embodiment of the present invention;

[0038] Figure 2 It is a schematic diagram of a guide vane structure optimization system according to an embodiment of the present invention;

[0039] Figure 3 It is a schematic diagram of the structural optimization of a guide vane structure according to an embodiment of the present invention, where (a) is a top view of the structure of the guide vane structure before and after optimization, and (b) is a bottom view of the structure of the guide vane structure before and after optimization. Detailed Embodiments

[0040] In order to make the purpose, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0041] The core of the embodiments of the present invention is to provide a guide vane structure optimization method, a guide vane structure optimization system, and a guide vane structure. In view of the problems of complex multi-physical field coupling analysis and low optimization efficiency in the design process of the guide vane of traditional pumps, a high-precision and rapid optimization design method for the guide vane structure is proposed.

[0042] An embodiment of the present invention on the one hand provides a method for optimizing the guide vane structure. Figure 1 As shown in the flowchart of a method for optimizing the guide vane structure according to an embodiment of the present invention, Figure 1 in this embodiment, the method for optimizing the guide vane structure specifically includes the following steps:

[0043] Step S1: Establish a parametric numerical model of the guide vane structure based on the multi-physics field coupling mechanism: establish an equivalent stress calculation model of the guide vane structure based on the coupling relationship between physical fields, and the equivalent stress is calculated through non-linear coupling of the fluid stress and centrifugal stress received by the guide vane structure.

[0044] Step S2: Establish a quantitative correlation between the key parameters of the guide vane structure and the stress response: establish an explicit relationship between the guide vane structure parameters and the equivalent stress according to the guide vane structure parameters that affect the stress received by the guide vane structure.

[0045] Step S3: Construct a multi-objective constraint optimization equation: based on the equivalent stress calculation model and the explicit relationship between the guide vane structure parameters and the equivalent stress, construct a structural optimization equation of the guide vane structure.

[0046] Step S4: Implement sequential quadratic programming iterative optimization: based on the structural optimization equation of the guide vane structure, use the SQP algorithm for iterative calculation until the optimization values of the guide vane structure parameters are obtained when the convergence condition is met.

[0047] Specifically, in step S1, the equivalent stress is calculated through non-linear coupling of the fluid stress and centrifugal stress received by the guide vane structure, and is specifically expressed as:

[0048] Construct the equivalent stress through the non-linear superposition principle : ;

[0049] where represents the equivalent stress of the guide vane structure, represents the fluid stress of the guide vane structure, represents the centrifugal stress of the guide vane structure, , , represent the weight coefficients, represents the yield strength of the guide vane structure material, is a linear term, and is directly weighted and summed according to the different influence weights of the fluid stress and centrifugal stress on the guide vane structure. The non-linear term reflects the double stress coupling effect, and the yield strength is introduced for normalization. After normalization, the influence of the high stress area is further amplified by squaring to improve the model accuracy of the non-linear term.

[0050] Specifically, in step S2, according to the guide vane structure parameters that affect the stress on the guide vane structure, specifically including:

[0051] Number of blades , inlet angle , blade thickness , blade wrap angle and diffusion angle ;

[0052] Among them, an explicit relationship between the guide vane structure parameters and the equivalent stress is established, that is, the parameter mapping relationship, specifically expressed as:

[0053] ;

[0054] The influence of the guide vane structure parameters ( , , , and ) on the stress on the guide vane structure is shown in the following table:

[0055]

[0056] Specifically, in step S3, a structural optimization equation for the guide vane structure is constructed, specifically including:

[0057] Taking the minimization of the equivalent stress as the objective function, a multi-variable optimization equation including the guide vane structure parameters is established, specifically expressed as:

[0058] ;

[0059] Define the geometric constraint conditions and performance constraint conditions of the guide vane structure as the boundary conditions of the optimization equation:

[0060] Geometric constraint: , , ;

[0061] The performance constraint is determined according to the head and efficiency coefficient of the pump installed with the guide vane structure;

[0062] The optimized values of the guide vane structure parameters are obtained by integral solution.

[0063] Specifically, in step S4, the convergence condition is expressed as the change rate of the equivalent stress being less than 1%.

[0064] Among them, in this embodiment, the fluid stress is composed of an impact stress term and a pressure load term to quantify the mechanical action of the fluid on the guide vane structure. The fluid stress is specifically expressed as:

[0065] , ;

[0066] Among them, and are expressed as empirical coefficients, is expressed as fluid density, is expressed as flow rate, is expressed as the area of a single flow channel, is expressed as the pressure difference across the flow channel, is expressed as the length of the guide vane, is expressed as the diameter of the guide vane, impact stress term is converted from fluid kinetic energy and is proportional to the square of the flow velocity ( ), and further it can be obtained that the flow velocity is inversely proportional to the number of blades , the area of a single flow channel and the inlet angle . Increasing these parameters can reduce the impact stress; the pressure load term is determined by the pressure difference across the flow channel and the length-to-thickness ratio of the blade ( ). The pressure load term reflects the bending stress of the guide vane structure blades. Further, it can be obtained that the larger the length-to-thickness ratio ( ), the more significant the blade bending stress. Reducing the blade thickness will increase the pressure of the pressure load term.

[0067] Among them, in this embodiment, the centrifugal stress is used to quantify the tensile effect of the rotational inertia force on the blade to avoid material overload. The centrifugal stress is specifically expressed as:

[0068] ;

[0069] Among them, is expressed as the density of the guide vane structure material, is expressed as the angular velocity, is expressed as the diameter of the guide vane, is expressed as the integral simplified model of the centrifugal force. The blade is approximated as a rectangular plate with equal thickness. The centrifugal force is integrated along the radius, and the integration result is . The volume of the blade is proportional to the blade thickness , the blade wrap angle and the square of the radius. The larger the volume, the higher the centrifugal stress. At the same time, the centrifugal stress is proportional to the density of the guide vane structure material and the square of the rotational speed ; reflects the mutual support effect of multiple blades. Increasing the number of blades will weaken the support effect, resulting in a slight increase in centrifugal stress.

[0070] Exemplarily, for each of the above steps, this embodiment provides a specific application scenario:

[0071] The following are the initial design parameters of the guide vane structure of a centrifugal pump ( =10 5 Pa) in this embodiment:

[0072]

[0073] Among them, the values of the weight coefficients are: 、 、 ;

[0074] The values of the empirical coefficients are: , ;

[0075] The first iterative calculation (initial parameters):

[0076] Calculate the fluid stress :

[0077] ;

[0078] Calculate the centrifugal stress :

[0079] ;

[0080] Calculate the equivalent stress :

[0081] ;

[0082] Calculate the partial derivatives of the structural optimization equation with respect to each guide vane structure parameter:

[0083] The partial derivative with respect to the number of blades :

[0084] ;

[0085] The partial derivative of the fluid stress with respect to the number of blades :

[0086] ;

[0087] The partial derivative of the centrifugal stress with respect to the number of blades :

[0088] ;

[0089] Obtain:

[0090] ;

[0091] That is when, increase the value of the equivalent stress is in a downward trend. According to the gradient descent method, the parameters of the number of blades are optimized. Since the calculated value is small, a small gradient change is adopted for optimization: , rounded to ;

[0092] Second iteration calculation ( ):

[0093] Calculate the fluid stress :

[0094] The process is the same as above, and is calculated;

[0095] Calculate the centrifugal stress :

[0096] The process is the same as above, and is calculated;

[0097] Calculate the equivalent stress :

[0098] The process is the same as above, and is calculated;

[0099] That is, the equivalent stress decreases by about 0.14% < 1% compared with the initial value, converges, and there is no need to continue optimization. The optimized value is . It should be noted that since the difference in calculating the equivalent stress and is small, it may have met the convergence condition when . It can be further verified by calculating . Similarly, it can be obtained that the number of blades has little influence on the equivalent stress .

[0100] Replace the guide vane structure parameters, calculate the partial derivative of the structure optimization equation with respect to the blade thickness . The calculation process is the same as above, and the partial derivative of the fluid stress with respect to the blade thickness is obtained:

[0101] ;

[0102] The partial derivative of the centrifugal stress with respect to the blade thickness :

[0103] ;​

[0104] Obtained:

[0105]

[0106] Due to the unit blade thickness (1m) has a large gap with the actual value (0.01m), so the calculation result is large. Similarly is negative, it can be seen that increasing the value of the equivalent stress shows a downward trend. The optimization adopts a large gradient change: ;

[0107] The third iterative calculation ( ):

[0108] Calculate the fluid stress :

[0109] The process is the same as above, and the calculated result is ;

[0110] Calculate the centrifugal stress :

[0111] The process is the same as above, and the calculated result is ;

[0112] Calculate the equivalent stress :

[0113] The process is the same as above, and the calculated result is ;

[0114] That is, the equivalent stress decreases by about 44.65% > 1% compared with the initial value, which means it has not converged and needs to be further optimized. The optimization process is the same as above.

[0115] The process is the same as above. Through further iterative calculation, the convergence value of the blade thickness is obtained. Then, the guide vane structure parameters are changed, and the partial derivatives of the structure optimization equation with respect to the inlet angle , the blade wrap angle and the diffusion angle are calculated. The calculation process is the same as above until all the guide vane structure parameters converge, and the optimized values of the guide vane structure parameters are obtained.

[0116] Among them, the geometric constraint conditions and performance constraint conditions of the guide vane structure are the boundary conditions of the optimization equation, that is, the optimized values of the guide vane structure parameters need to satisfy the boundary conditions.

[0117] In this embodiment, there is also a guide vane structure optimization system for implementing a guide vane structure optimization method as described above, Figure 2 which is a schematic diagram of a guide vane structure optimization system according to an embodiment of the present invention, as shown in Figure 2As shown, the guide vane structure optimization system includes:

[0118] A parameter input module: used to receive guide vane structure parameters and operating condition parameters;

[0119] A stress calculation module: performing equivalent stress calculation according to the equivalent stress calculation model;

[0120] An optimization algorithm module: calculating the optimized values of the guide vane structure parameters based on the SQP algorithm according to the structure optimization equation;

[0121] A structure output module: outputting the optimization result of the guide vane structure.

[0122] Specifically, on the other hand, this embodiment also provides a guide vane structure. Figure 3 It is a schematic diagram of the structure optimization of a guide vane structure according to an embodiment of the present invention. As Figure 3 shown, this guide vane structure is optimized and implemented according to the above-mentioned guide vane structure optimization system. Among them, (a) is the top view of the structure of this guide vane structure before and after optimization, and (b) is the bottom view of the structure of this guide vane structure before and after optimization.

[0123] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. An optimization method for a guide vane structure, characterized in that It includes the following steps: Step S1: Establish a parametric numerical model of the guide vane structure based on the multi-physical field coupling mechanism: establish an equivalent stress calculation model of the guide vane structure based on the coupling relationship between physical fields, and the equivalent stress is calculated by non-linear coupling of the fluid stress and centrifugal stress suffered by the guide vane structure; Step S2: Establish a quantitative correlation between the key parameters of the guide vane structure and the stress response: establish an explicit relationship between the guide vane structure parameters and the equivalent stress according to the guide vane structure parameters that affect the stress suffered by the guide vane structure; Step S3: Construct a multi-objective constraint optimization equation: construct a structural optimization equation of the guide vane structure based on the equivalent stress calculation model and the explicit relationship between the guide vane structure parameters and the equivalent stress; Step S4: Implement sequential quadratic programming iterative optimization: based on the structural optimization equation of the guide vane structure, use the SQP algorithm for iterative calculation until the optimization value of the guide vane structure parameters is obtained when the convergence condition is met.

2. The optimization method of a guide vane structure as claimed in claim 1, wherein In the said Step S1, the equivalent stress is calculated by non-linear coupling of the fluid stress and centrifugal stress suffered by the guide vane structure, and is specifically expressed as: Construct the equivalent stress through the principle of non-linear superposition : ; Among them, represents the equivalent stress of the guide vane structure, represents the fluid stress of the guide vane structure, represents the centrifugal stress of the guide vane structure, , , represent the weight coefficients, represents the yield strength of the guide vane structure material.

3. The optimization method for a guide vane structure according to claim 2, wherein In the said Step S2, according to the guide vane structure parameters that affect the stress suffered by the guide vane structure, it specifically includes: Number of blades , inlet angle , blade thickness , blade wrap angle and diffusion angle ; Among them, an explicit relationship between the guide vane structure parameters and the equivalent stress is established, that is, the parameter mapping relationship, which is specifically expressed as: 。 4. A method for optimizing the guide vane structure according to claim 3, characterized in that In the said Step S3, construct a structural optimization equation of the guide vane structure, which specifically includes: Taking the equivalent stress as the objective function to be minimized, a multi-variable optimization equation including the guide vane structure parameters is established, which is specifically expressed as: ； Define the geometric constraint conditions and performance constraint conditions of the guide vane structure as the boundary conditions of the optimization equation.

5. A method for optimizing a guide vane structure according to claim 1, characterized in that In the said Step S4, the convergence condition is expressed as the change rate of the equivalent stress being less than 1%.

6. The optimization method of a guide vane structure according to claim 3, characterized in that Fluid stress is composed of an impact stress term and a pressure load term to quantify the mechanical action of the fluid on the guide vane structure. The fluid stress is specifically expressed as: ； Among them, and are expressed as empirical coefficients, is expressed as fluid density, is expressed as flow rate, is expressed as the area of a single flow channel, is expressed as the pressure difference across the flow channel, is expressed as the length of the guide vane.

7. A method for optimizing the guide vane structure according to claim 3, characterized in that Centrifugal stress Used to quantify the tensile effect of the rotational inertia force on the blade, centrifugal stress Specifically expressed as: ； Among them, represents the density of the guide vane structure material, represents the angular velocity, represents the guide vane diameter.

8. A guide vane structure optimization system for implementing a guide vane structure optimization method according to any one of claims 1-7, characterized in that, It includes: Parameter input module: used to receive the guide vane structure parameters and working condition parameters; Stress calculation module: calculate the equivalent stress according to the equivalent stress calculation model; Optimization algorithm module: calculate the optimization value of the guide vane structure parameters based on the SQP algorithm according to the structural optimization equation; Structure output module: output the optimization result of the guide vane structure.

9. A guide vane structure, characterized in that, Optimization implementation according to a guide vane structure optimization system as claimed in claim 8.

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