A high-temperature blended valve thermal fluctuation suppression structure design method

Abstract

The application discloses a high-temperature blending valve thermal fluctuation suppression structure design method, comprising the following steps: determining basic parameters of a high-temperature blending valve, and establishing a three-dimensional geometric model thereof; extracting a calculation domain of the three-dimensional geometric model, and performing mesh division; adopting an improved large eddy simulation method to perform numerical simulation on the calculation domain after the mesh division; calculating temperature fluctuation intensity and temperature power spectral density according to a result of the numerical simulation; taking minimization of maximum values of the temperature fluctuation intensity and the temperature power spectral density as double targets, and constructing a thermal fluctuation suppression evaluation criterion fusing time domain and frequency domain; introducing axial temperature change rate and circumferential temperature relative deviation as a mixing uniformity constraint condition, limiting a lower limit of candidate structure performance, and based on the thermal fluctuation suppression evaluation criterion, jointly optimizing structure parameters and operation control parameters of the blending valve. The application is suitable for optimization design of blending valves under high-temperature working conditions such as sulfur recovery, coal chemical industry and petroleum refining.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-temperature valve design, in particular to a high-temperature blending valve thermal fluctuation suppression structure design method. BACKGROUND

[0002] The high-temperature blending valve is the core equipment in the Claus process of the sulfur recovery unit, which is responsible for the dynamic mixing of high-temperature gas flow and low-temperature bypass gas flow, and adjusts the mixing ratio of cold and hot fluids to ensure that the reactor inlet temperature is stable in the optimal range required for sulfur conversion. However, during the operation of the valve, there is a serious "thermal fluctuation" problem, which causes the internal temperature of the valve to change dramatically and periodically. This not only affects the accuracy of temperature control, but also exacerbates the thermal fatigue effect of the valve, thereby shortening its service life.

[0003] Currently, the design of the blending valve usually relies on the selection of higher-grade high-temperature resistant materials and the increase of wall thickness to withstand thermal load. Although these measures effectively improve the high-temperature resistance, they significantly increase the manufacturing cost and fail to fundamentally solve the problem of thermal stress generation and concentration. Therefore, there is an urgent need for a new design method to actively suppress thermal fluctuations, reduce thermal fluctuation intensity from the source, and improve the thermal fatigue resistance of the valve. SUMMARY

[0004] The present application aims to solve the technical problems of existing high-temperature blending valves, such as severe thermal fluctuations during the mixing of cold and hot fluids, high thermal fatigue risk, and unstable structural response. A high-temperature blending valve thermal fluctuation suppression structure design method is provided, which realizes effective suppression of the internal thermal fluctuation behavior of the high-temperature blending valve through numerical simulation, criterion construction, and multi-objective optimization technology, thereby improving its thermal stability and service life.

[0005] According to an embodiment of the present application, a high-temperature blending valve thermal fluctuation suppression structure design method is provided, comprising:

[0006] S1: Determine the basic parameters of the high-temperature blending valve and establish its three-dimensional geometric model;

[0007] S2: Extract the calculation domain of the three-dimensional geometric model and perform mesh division;

[0008] S3: Numerically simulate the mesh-divided calculation domain using an improved large eddy simulation method, which includes: constructing a density-weighted filtering system to handle density changes in compressible flow fields; establishing a dynamic nonlinear eddy viscosity-helicity coupling subgrid stress model to simulate small-scale turbulent structures; and adopting an adaptive grid refinement strategy based on a vorticity and temperature gradient joint criterion;

[0009] S4: Calculate the temperature fluctuation intensity and temperature power spectral density according to the results of the numerical simulation;

[0010] S5: With minimizing the maximum value of temperature fluctuation intensity and the maximum value of temperature power spectral density as dual objectives, a thermal fluctuation suppression evaluation criterion integrating the time domain and frequency domain is constructed.

[0011] S6: Introduce the relative deviation between axial temperature change rate and circumferential temperature as a constraint condition for mixing uniformity, limit the lower limit of candidate structure performance, and jointly optimize the structural parameters and operation control parameters of the mixing valve based on the thermal fluctuation suppression evaluation criterion.

[0012] Optionally, the dynamic nonlinear eddy viscosity-helicity coupled subgrid stress model is as follows:

[0013] ;

[0014] The three terms on the right-hand side of the equation are: the second-order filter dynamic stress term, the velocity gradient nonlinear term, and the helicity term; These are the model coefficients. For grid scale, The modulus of the density-weighted strain rate tensor These are the components of the strain rate tensor. For adjustment coefficients, For velocity components exist Partial derivatives in direction, For velocity components exist Partial derivatives in direction, For local scale, These are the components of the rotation rate tensor.

[0015] Optionally, the adaptive mesh refinement strategy based on the joint criterion of vorticity and temperature gradient includes:

[0016] The following criterion function ψ is used to control the mesh refinement in key areas:

[0017] ;

[0018] In the formula The vorticity vector. For the inlet flow rate, D For pipe diameter, For density-weighted temperature gradient, This represents the extreme value of the temperature difference between the hot and cold fluids;

[0019] Based on the numerical value of the criterion function ψ, a hierarchical adaptive grid encryption partitioning is performed.

[0020] Optionally, hierarchical adaptive mesh refinement is performed, including:

[0021] When a1≤ Ψ When a2≤

[0022] When a2≤ Ψ When a3≤

[0023] When a3≤ Ψ When a3≤

[0024] When a4≤ Ψ When a4≤

[0025] Wherein a4≤a1<a2<a3, a1 is the trigger threshold of Level 1 encryption, a2 is the trigger threshold of Level 2 encryption, a3 is the trigger threshold of Level 3 encryption, and a4 is the trigger threshold of the grid merging operation; the unit grid size of the Level 1 encryption region is 1 / 2 of the original grid, the unit grid size of the Level 2 encryption region is 1 / 4 of the original grid, and the unit grid size of the Level 3 encryption region is 1 / 8 of the original grid.

[0026] Optionally, a thermal fluctuation suppression evaluation criterion integrating time domain and frequency domain is constructed with the dual objectives of minimizing the maximum temperature fluctuation intensity and the maximum temperature power spectral density, including:

[0027] Determining the maximum temperature fluctuation intensity and the point where it is located, and setting temperature monitoring points at the point and its adjacent cross sections to collect temperature time series;

[0028] Performing Fourier transform on the temperature time series to obtain the temperature power spectral density distribution of the monitoring points, and extracting the maximum temperature power spectral density PSD max ;

[0029] With the key indicators of minimizing and PSD max , a thermal fluctuation suppression evaluation criterion integrating time domain and frequency domain is constructed to realize quantitative evaluation of thermal fluctuations.

[0030] Optionally, a non-dominated sorting genetic algorithm (NSGA-II) is used to perform multi-objective joint optimization on the structural parameters and operation control parameters of the blending valve.

[0031] Optionally, the formula for calculating the axial temperature change rate is as follows:

[0032] ;

[0033] wherein, R is the axial temperature variation rate, a is the average temperature of the axial position, , is the average temperature of the axial position, i -1 and i is the average temperature of the axial position.

[0034] Optionally, the calculation formula of the circumferential temperature relative deviation is as follows:

[0035] ;

[0036] wherein, RS is the circumferential temperature relative deviation, S is the standard deviation of the axial position temperature, is the average temperature of the axial position.

[0037] Optionally, the structural parameters include the blending valve opening degree, the opening angle, the branch pipe outflow area and the structure and arrangement form of the downstream mixer.

[0038] Optionally, the operation regulation parameters include the cold and hot flow velocity ratio, the temperature ratio and the total flow.

[0039] The technical scheme provided by the embodiment of the application can include the following beneficial effects:

[0040] The improved large eddy simulation (LES) method combined with the density weighted filtering system is adopted, so that the unsteady characteristics and small scale turbulent structure in the mixing process of cold and hot fluids can be accurately captured, and the small scale turbulence is simulated through the establishment of a dynamic nonlinear vortex viscosity-helicity coupling sub-grid stress model. In addition, based on the vortex-temperature gradient double criterion, the adaptive grid refinement strategy is realized, so that the fine grid division of the key area and the grid merging of the invalid area are realized, and the calculation precision is significantly improved and the calculation cost is reduced.

[0041] The minimum temperature fluctuation intensity and the minimum temperature power spectrum density are taken as the double optimization targets, an evaluation criterion of thermal fluctuation suppression is constructed by fusing the time domain and the frequency domain, the influence of each structure and operation parameter on the thermal fluctuation is quantified through global sensitivity analysis, the dominant variable is identified, so that blind optimization is avoided, and the pertinence and practicality of the design are improved. On this basis, the structure and the regulation parameter of the blending valve are optimized, and the optimal thermal fluctuation suppression scheme is obtained.

[0042] The axial temperature variation rate and the circumferential temperature relative deviation are introduced as the mixing uniformity constraint indexes, so that the stability and uniformity of the temperature distribution at the outlet of the blending valve are ensured, the strict requirement of the process on the temperature control precision is met, and the conversion efficiency and the operation stability of the downstream reactor are improved.

[0043] The thermal fluctuation suppression evaluation criterion and optimization method can effectively improve the performance of the high-temperature blending valve, has significant economic benefits and technical advantages, and can be widely applied to the design and modification of various thermal flow devices, and has good industrial application prospects.

[0044] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory and are not restrictive of the application. BRIEF DESCRIPTION OF DRAWINGS

[0045] The accompanying drawings incorporated in and forming a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0046] Figure 1 A high-temperature blending valve thermal fluctuation suppression design method flow chart is shown according to an exemplary embodiment.

[0047] Figure 2 A high-temperature blending valve three-dimensional geometric model diagram is shown according to an exemplary embodiment.

[0048] Figure 3 A high-temperature blending valve internal flow passage structured grid diagram is shown according to an exemplary embodiment.

[0049] Figure 4 An adaptive three-level grid encryption division diagram is shown according to an exemplary embodiment.

[0050] Figure 5 A high-temperature blending valve pipe wall and valve rear pipe setting monitoring point position diagram is shown according to an exemplary embodiment.

[0051] Figure 6 A thermal fluctuation suppression evaluation criterion flow chart is shown according to an exemplary embodiment. DETAILED DESCRIPTION

[0052] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The following description is made with reference to the accompanying drawings in which like reference numerals refer to like elements in the several figures. The following detailed description is not intended to limit the application, as claimed.

[0053] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in this application and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or," as used herein, refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0054] Figure 1 A high-temperature mixing valve thermal fluctuation suppression design method flow chart according to an exemplary embodiment is shown in FIG. 1, which includes the following steps: Figure 1

[0055] S1: Determine the basic parameters of the high-temperature mixing valve, and establish its three-dimensional geometric model;

[0056] Specifically, according to the actual structure in the engineering, the parameters of the high-temperature mixing valve are determined, the inner pipe diameter D m = 400 mm, the branch pipe flow channel D b = 90 mm, the valve core cross-section width D1 = 124 mm, the height D2 = 110 mm, the valve rod diameter D3 = 52 mm, the valve body outlet to valve rod distance D4 = 438 mm, the valve body outlet length D5 = 390 mm, the valve seat insulation layer D6 = 600 mm, and the main geometric parameters are shown in Table 1. According to the parameters, the three-dimensional geometric model of the mixing valve is established in the SolidWorks software, as shown in FIG. 2. Figure 2

[0057] Table 1 Structural parameters

[0058]

[0059] S2: Extract the calculation domain of the three-dimensional geometric model, and perform meshing;

[0060] Specifically, in order to improve the fluid mixing efficiency of the high-temperature mixing valve and accurately reflect the temperature variation characteristics in the flow process, the internal structure of the mixing valve is first simplified and the flow channel is extracted. And the internal flow channel is extended to fully mix the fluid and enhance the cold and hot fluid mixing effect. The specific measures include: the upstream main pipeline is extended by 5 times the main flow pipe diameter in the main flow direction, and the extension length is 2500 mm; the downstream main pipeline is extended by 10 times the main flow pipe diameter, and the extension length is 4500 mm; the branch pipe is extended by 5 times the branch pipe diameter, and the extension length is 500 mm. The above design optimization helps to slow down the intense shear mixing process, improve the thermal fluctuation development environment, and improve the mixing uniformity.

[0061] On the basis of the above structure, the ANSYS ICEM software is used to perform structured meshing on the internal flow channel of the mixing valve (as shown in FIG. 3). Figure 3 ​​As shown in the figure, to ensure the flow field resolution and result reliability during numerical simulation. To improve simulation stability and computational accuracy, the overall value of the Jacobian determinant (3×3×3) was strictly controlled to be greater than 0.6 during mesh generation to ensure that the mesh quality meets the requirements of high-precision numerical calculation. The first layer mesh height in the main pipe region was set to 0.16 mm, and the first layer mesh height in the branch pipe region was set to 0.11 mm. For the complex geometric region near the valve core, local mesh refinement was implemented to more precisely capture the local vortex structure and thermal fluctuation development behavior, providing an accurate basis for subsequent flow and thermal response analysis.

[0062] S3: An improved large eddy simulation method is used to perform numerical simulation on the computational domain after mesh generation;

[0063] Specifically, the improved large eddy simulation method includes:

[0064] 1) Construct a density-weighted filtering system to handle density variations in compressible flow fields;

[0065] Specifically, define the density-weighted variable:

[0066]

[0067] In the formula For density-weighted filtering variables, The spatial average density, The instantaneous value of the original physical quantity. It is a density-weighted average.

[0068] Reconstructing the continuity equation:

[0069]

[0070] In the formula For density-weighted velocity vectors, For divergence operators, It is a density-weighted average.

[0071] To address the dynamic equilibrium of pressure, density, and temperature, and avoid thermodynamic distortion after traditional filtering, a density-weighted filtered equation of state is introduced.

[0072]

[0073] In the formula For quality-weighted average pressure, For average density, R The gas constant is Temperature is the density-weighted average temperature.

[0074] 2) Establish a dynamic nonlinear eddy viscosity-helicity coupled subgrid stress model to simulate small-scale turbulent structures;

[0075] Specifically, the dynamic nonlinear eddy-viscosity-helicity coupling sub-grid stress model is represented as follows:

[0076]

[0077] where the three terms on the right side of the equation are respectively the quadratic filtering dynamic stress term, the velocity gradient nonlinear term and the helicity term; is a model coefficient, is the grid scale, is the norm of the density-weighted strain rate tensor, is the component of the strain rate tensor, is an adjustment coefficient, is the partial derivative of the velocity component in the direction, is the partial derivative of the velocity component in the direction, is the local scale, is the component of the spin rate tensor.

[0078] 3) An adaptive grid refinement strategy based on the joint criterion of vorticity and temperature gradient is adopted;

[0079] Specifically, the grid refinement control of the key area is realized by the following criterion function ψ:

[0080]

[0081] where is the vorticity vector, is the inlet flow velocity, D is the pipe diameter, is the density-weighted temperature gradient, is the extreme value of the temperature difference between the cold and hot fluids;

[0082] Referring to Figure 4 , based on the numerical value of the criterion function ψ, a hierarchical adaptive grid refinement division is performed, which specifically includes:

[0083] When a1≤ Ψ < a2, Level 1 grid refinement is performed to capture large-scale shear layers;

[0084] When a2≤ Ψ < a3, Level 2 grid refinement is performed to enhance the resolution of the cold-hot mixing interface;

[0085] When Ψ ≥ a3, Level 3 grid refinement is performed to capture vortex core structures;​​

[0086] When Ψ When a4, trigger the grid merging operation of the corresponding region;

[0087] Wherein a4≤a1 The unit grid size of the Level 1 encrypted region is 1 / 2 of the original grid, that is, the length of each unit becomes 1 / 2 of the original, and the volume is 1 / 8 of the original; the unit grid size of the Level 2 encrypted region is 1 / 4 of the original grid, that is, the length of each unit becomes 1 / 4 of the original, and the volume is 1 / 64 of the original; the unit grid size of the Level 3 encrypted region is 1 / 8 of the original grid, that is, the length of each unit becomes 1 / 8 of the original, and the volume is 1 / 512 of the original.

[0088] The improved large eddy simulation method is used to simulate the numerical simulation of the grid divided calculation domain;

[0089] Specifically, the grid model of the blending valve internal flow channel is imported into the Fluent software, the "grid unit" and "domain range" in the "general" column "grid scaling" option are checked, and the "steady state" and "gravity acceleration" are set; check the "energy" option in the "model" column; set the "k-e" turbulence model in the "model" column; set the fluid region as single-phase gas; set "mass-flow-inlet" and "mass-flow-outlet" in the "boundary condition" column, and set the inlet flow temperature of the main flow channel and branch pipe flow channel; select "SIMPLE" pressure velocity coupling in the "solution method" column; set the convergence residual value in the "calculation monitoring" column; set "all-zones standard initialization" in the "initialization" column, complete the initialization; set the "time step" in the "calculation setting" column, start steady-state numerical calculation until convergence.

[0090] After the single-phase gas-stable flow field is obtained, transient numerical calculation is performed, "transient" is set in the "general" column, "large eddy simulation (LES)" turbulence model is set in the "model" column, density weighting processing of physical quantities is performed through User Defined Function (UDF) in Fluent, the compressible LES mode is activated through the density-based solver of Fluent, and the state equation is modified to a density-weighted state expression through UDF; in Fluent, the momentum source term is defined through UDF and embedded into the momentum equation, and the term is integrated into the source term setting module of the momentum equation and embedded in the form of an explicit source term. The dynamic nonlinear eddy viscosity-helicity coupling subgrid stress model is realized through the User-Defined Subgrid Scale (UDSGS) model interface in the LES model module in Fluent, and the user realizes the self-defined expression form of the stress tensor through the DEFINE_SGS_STRESS UDF subroutine, and the system is automatically loaded when called. The subgrid heat flux model is defined through UDF, and the heat flux expression is embedded in the source term part of the Fluent energy equation, the DEFINE_SOURCE macro definition interface is called and dynamically updated according to the local state of the calculation domain. In order to balance the calculation accuracy and efficiency, an adaptive grid refinement function based on the joint criterion of vorticity intensity and temperature gradient is constructed, the AMR function is realized through the dynamic adaptive mesh module (Dynamic Mesh - Adaptive Remeshing) in Fluent, and the refinement levels are configured through the following hierarchical strategy: when ψ≥0.6: Level 3 grid refinement is performed; when 0.3≤ Ψ <0.6: Level 2 refinement is performed; when 0.1≤ Ψ <0.3: Level 1 refinement is performed; when ψ<0.1: the region merging operation is triggered. The "PISO" pressure-velocity coupling is selected, and the transient formula is set to bounded second-order implicit. A plurality of monitoring points are set in the blending valve pipe wall and the downstream pipe to collect temperature fluctuation data of different cross-section pipe walls, 8 monitoring points are uniformly arranged on each monitoring surface, as shown in Figure 5 The time step number and time step length are set, and transient numerical calculation is performed.

[0091] S4: calculating the temperature fluctuation intensity and the temperature power spectral density according to the results of the numerical simulation;

[0092] Specifically, to quantify the temperature fluctuation intensity, the dimensionless root mean square temperature is used as the evaluation index. The analysis process uses the Monitor function of Fluent combined with the Transient Simulation data export function to extract the temperature-time sequence and then complete the calculation.

[0093] Dimensionless root mean square temperature The formula is as follows:

[0094]

[0095] In the formula, is the dimensionless mean temperature, , is the dimensionless instantaneous temperature, , N is the data quantity of the temperature measurement point, T i is the instantaneous temperature of the measurement point.

[0096] To reveal the frequency distribution characteristics of thermal fluctuations, Fourier transform is used to perform frequency domain analysis on the temperature time sequence signal to obtain the temperature power spectral density. After the simulation is completed in Fluent, the data sequence of temperature change over time is exported, and the FFT toolbox is called in MATLAB to perform frequency domain transformation to obtain the energy distribution of each monitoring point at different frequencies, which is used to identify the thermal shock frequency band and the high fluctuation area.

[0097] Temperature power spectral density The calculation method is as follows:

[0098]

[0099] In the formula is the frequency domain representation of Fourier transform, is the frequency variable, is the temperature fluctuation, and t is time.

[0100] S5: To minimize the maximum value of temperature fluctuation intensity and the maximum value of temperature power spectral density, a thermal fluctuation suppression evaluation criterion is constructed by fusing time domain and frequency domain; reference Figure 6 , including the following sub-steps:

[0101] S51: Determine the maximum value of wall surface temperature fluctuation intensity and the point where it is located, and set temperature monitoring points at the point and its adjacent sections to collect temperature time variation sequences;

[0102] Specifically, first, the wall surface temperature fluctuation intensity of each point is calculated, compared, and the maximum value of wall surface temperature fluctuation intensity is determined The point where the maximum value of the wall temperature fluctuation intensity is found. Then, a plurality of high-precision temperature monitoring points are arranged around the maximum fluctuation point and its surrounding area, and temperature time variation sequences are collected. These monitoring points should be selected in places where there may be strong heat flow changes, and should be arranged as uniformly as possible to ensure that the temperature changes in the entire area can be fully reflected. The data acquisition system should have high sampling rate and real-time transmission capability to capture the subtle fluctuations of temperature.

[0103] S52: Fourier transform is performed on the temperature time sequence to obtain the temperature power spectral density distribution of the monitoring points, and the maximum value of the temperature power spectral density is extracted therefrom PSD max ;

[0104] Specifically, first, the collected temperature time sequence data is preprocessed to ensure the accuracy of the data. Then, Fourier transform is applied to convert the temperature data in the time domain to frequency domain data, thereby obtaining the power spectral density of the temperature. When performing Fourier transform, an appropriate window function needs to be selected to reduce the frequency domain leakage effect and improve the resolution of the frequency spectrum. Then, in the obtained power spectral density distribution, the maximum power spectral density value at the corresponding frequency is found, denoted as PSD max .

[0105] S53: Taking the minimum and PSD max as key indicators, a thermal fluctuation suppression evaluation criterion integrating time domain and frequency domain is constructed to realize quantitative evaluation of thermal fluctuation;

[0106] Specifically, after obtaining the temperature fluctuation information of multiple monitoring points, a thermal fluctuation suppression evaluation criterion for design optimization is constructed to realize systematic identification and control of high-temperature disturbance. The maximum value of the dimensionless root mean square temperature near the pipe wall area is extracted, denoted as , to represent the position of high fluctuation most prone to thermal fatigue; at the same time, the maximum peak value in the temperature power spectral density curve of each monitoring point is obtained, denoted as PSD max , to identify the thermal energy concentration area under the dominant frequency. On this basis, a comprehensive evaluation model is constructed to minimize and PSD max , to realize collaborative control of time domain fluctuation intensity and frequency domain energy distribution, and to provide a unified thermal fluctuation suppression design criterion for subsequent structure parameter optimization and operation control.

[0107] S6: Introducing the axial temperature change rate and the circumferential temperature relative deviation as the mixing uniformity constraint condition, limiting the lower limit of the candidate structure performance, based on the thermal fluctuation suppression evaluation criterion, jointly optimizing the structure parameters and operation control parameters of the blending valve;

[0108] Specifically, the axial temperature change rate is calculated as follows:

[0109] ;

[0110] In the formula, T (i) and T (i+1) are the average temperatures at axial positions i and i+1, respectively. , i i

[0111] The calculation formula of the circumferential temperature relative deviation RS is as follows:

[0112] ;

[0113] In the formula, S is the standard deviation of the axial position temperature, and T (i) is the average temperature at axial position i.

[0114] To effectively suppress the thermal fluctuation inside the blending valve caused by high-temperature mixing, the present application adopts the non-dominated sorting genetic algorithm (NSGA-II) to perform multi-objective optimization design on the key structure and working condition parameters based on the constructed thermal fluctuation suppression criterion. First, the global sensitivity analysis method is used to quantitatively evaluate the influence of each parameter on the maximum temperature fluctuation intensity and the maximum power spectrum density peak PSD max , and the main design variables and their optimization intervals are selected, including the structure parameters and the operation control parameters. The structure parameters include the blending valve opening, the opening angle, the branch pipe outflow area, and the structure and arrangement of the downstream mixer. The operation control parameters include the cold and hot flow velocity ratio, the temperature ratio, and the total flow, etc. To ensure the mixing uniformity and engineering feasibility, two constraint indicators, the axial temperature change rate Ra and the circumferential temperature relative deviation RS, are set, with RS ≤ λ3 (5% to 10%) and Ra ≤ λ4 (3% to 7%). Based on the gamultiobj tool of MATLAB, the optimization model of minimizing and PSD max is constructed and solved to obtain the Pareto optimal solution. Finally, the optimized parameters are substituted back into the Fluent simulation model to verify the thermal fluctuation suppression effect, and the performance optimal solution is selected as the final structure design scheme.

[0115] ​​​​Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the application embrace any and all variations of the present application that fall within the scope of the general inventive concept as defined by the appended claims and their equivalents. The specification and examples are to be regarded as exemplary in nature and not as restrictive in any way.

[0116] It should be understood that the application is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application is to be defined by the appended claims rather than by the description preceding them.

Claims

1. A high-temperature blended valve thermal fluctuation suppression structure design method, characterized by, The application relates to a method for optimizing the structure and operation of a high-temperature mixing valve, comprising the following steps: S1: determining the basic parameters of the high-temperature mixing valve and establishing a three-dimensional geometric model thereof; S2: extracting the calculation domain of the three-dimensional geometric model and carrying out mesh division; S3: adopting an improved large eddy simulation method to carry out numerical simulation on the calculation domain after mesh division, wherein the improved large eddy simulation method comprises the following steps: constructing a density-weighted filtering system to process the density change in a compressible flow field; establishing a dynamic nonlinear vortex viscosity-helicity coupling sub-grid stress model to simulate small-scale turbulent flow structures; and adopting an adaptive grid refinement strategy based on a vortex and temperature gradient joint criterion; S4: calculating the temperature fluctuation intensity and the temperature power spectral density according to the result of the numerical simulation; S5: constructing a thermal fluctuation suppression evaluation criterion integrating time domain and frequency domain by taking the minimization of the maximum value of the temperature fluctuation intensity and the maximum value of the temperature power spectral density as double objectives; S6: introducing an axial temperature change rate and a circumferential temperature relative deviation as a mixed uniformity constraint condition to limit the lower limit of the performance of a candidate structure, and jointly optimizing the structure parameters and operation control parameters of the mixing valve based on the thermal fluctuation suppression evaluation criterion.

2. The high-temperature blended valve thermal fluctuation suppression structural design method of claim 1, wherein The dynamic nonlinear vortex viscosity-helicity coupling sub-grid stress model is as follows: ； The three terms on the right-hand side of the equation are: the second-order filter dynamic stress term, the velocity gradient nonlinear term, and the helicity term; These are the model coefficients. For grid scale, The modulus of the density-weighted strain rate tensor These are components of the strain rate tensor. For adjustment coefficients, For velocity components exist Partial derivatives in direction, For velocity components exist Partial derivatives in direction, For local scale, These are the components of the rotation rate tensor.

3. The high temperature blended valve thermal fluctuation suppression structural design method of claim 1, wherein The adaptive grid refinement strategy based on the vortex and temperature gradient joint criterion comprises the following steps: The grid refinement control of a key region is realized through the following criterion function ψ: ； wherein is the vorticity vector, is the inlet flow velocity, D is the pipe diameter, is the density-weighted temperature gradient, is the cold-hot fluid temperature difference extreme; Based on the numerical value of the criterion function ψ, hierarchical adaptive grid refinement division is executed.

4. The high temperature blended valve thermal fluctuation suppression structural design method of claim 1, wherein The hierarchical adaptive grid refinement division comprises the following steps: When a1≤ ψ When a2, perform Level 1 grid refinement to capture large scale shear layers; When a2≤ ψ When a3, Level 2 grid refinement is performed to enhance the resolution of the cold-hot mixing interface. When ψ When a3, perform Level 3 grid refinement to capture vortex core structure; When ψ When a4, trigger the grid merge operation of the corresponding region; Wherein a4<=a1 5. The high temperature blended valve thermal fluctuation suppression structural design method of claim 1, wherein The structure parameters of the mixing valve comprise a mixing valve opening degree, an opening angle, a branch pipe outflow area and the structure and arrangement form of a downstream mixer. Determining a wall surface temperature fluctuation intensity maximum and the point thereof, and setting a temperature monitoring point at the point and adjacent cross sections thereof, and collecting a temperature time sequence; performing Fourier transform on the temperature time sequence to obtain a temperature power spectral density distribution of the monitoring point, and extracting a maximum value of the temperature power spectral density from the temperature power spectral density distribution The operation control parameters of the mixing valve comprise a cold and hot flow velocity ratio, a temperature ratio and a total flow. max ; To minimize and ​ max A thermal fluctuation suppression evaluation criterion combining time domain and frequency domain is constructed to realize quantitative evaluation of thermal fluctuation.

6. The method of claim 1, wherein the method is characterized by: ​ 7. The method of claim 1, wherein the method is characterized by: ​ ； wherein is the axial temperature change rate, , is the average temperature at the axial i -1 and i position.

8. The method of claim 1, wherein the method is characterized by: ​ ； wherein Rsis the circumferential temperature relative deviation, S is the standard deviation of the temperature at the axial position, is the average temperature at the axial i position.

9. The method of claim 1, wherein the method is characterized by: ​ 10. The method of claim 1, wherein the method is a method of designing a high-temperature blended valve thermal fluctuation suppression structure, characterized by: ​

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