Hydraulic design method for double-channel impeller of nuclear island pit pump

Abstract

The application discloses a nuclear island pit pump double-flow channel impeller hydraulic design method and relates to the technical field of impeller hydraulic design, in order to solve the problem of reduced design precision of the double-flow channel. The application realizes the comprehensiveness and traceability of data through the innovation of full-process working condition parameter confirmation and performance index definition, retrieves multi-dimensional parameters from a database and establishes an identifier, ensures that source data is reliable, divides the flow of symmetrical flow channels, reduces the resistance of streamline spacers, optimizes the flow field in combination with fluid dynamics simulation, reduces vortex and hydraulic loss, verifies the compatibility through finite element analysis, improves the structural strength while guaranteeing the hydraulic performance, and verifies the equipment resistance to radiation, high temperature and other influences in extreme working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of impeller hydraulic design, in particular to a nuclear island pit pump double-flow channel impeller hydraulic design method. BACKGROUND

[0002] As a key safety equipment of nuclear power plant, the nuclear island pit pump needs to transport impurity-containing, high-temperature and possibly radioactive medium under extreme working conditions, and the requirements for impeller hydraulic performance and structural reliability are strict. In the existing design, the working condition parameters are not fully collected and lack of traceability mechanism, resulting in insufficient reliability of basic data; the performance indicators are extracted ambiguously, and there is no clear nuclear safety priority when conflicts occur, which is easy to deviate from the safety core; the material selection and working condition adaptability are poor, and there is a lack of nuclear level verification, and the anti-wear and radiation resistance performance is insufficient; the flow channel design symmetry is poor, the impeller and volute are not well matched, the hydraulic loss is large, the efficiency is low, and the structural strength and hydraulic performance are difficult to balance, which is easy to fail due to high stress and wear, and is difficult to meet the long-term safety operation requirements of nuclear island. SUMMARY

[0003] The purpose of the present application is to provide a nuclear island pit pump double-flow channel impeller hydraulic design method, which realizes the comprehensiveness and traceability of data through the innovation of whole-process working condition parameter confirmation and performance indicator definition, retrieves multi-dimensional parameters from the database and establishes identification, ensures the reliability of source data, divides the flow equally for symmetrical flow channels, reduces the resistance for streamline splitter, optimizes the flow field combined with fluid dynamics simulation, reduces vortex and hydraulic loss, improves structural strength while ensuring hydraulic performance through finite element analysis and compatibility verification, and ensures that the equipment can resist the influence of radiation, high temperature and other factors, which can solve the problems in the prior art.

[0004] To achieve the above purpose, the present application provides the following technical scheme:

[0005] The nuclear island pit pump double-flow channel impeller hydraulic design method comprises:

[0006] First, the parameter data of the original working condition is confirmed; the performance indicators are defined according to the confirmed working condition parameter data; the material is designed and selected according to the working condition parameter data and the performance indicators; the basic flow channel structure of the double-flow channel impeller is constructed according to the performance indicators, and a flow channel three-dimensional model is constructed according to the basic flow channel structure; the hydraulic performance of the initial impeller under the set working condition is analyzed by using the flow channel three-dimensional model; the impeller and volute are matched according to the hydraulic performance analysis result, and the shape of the blade is optimized; the structure of the matched and optimized impeller, volute and blade is strengthened; the hydraulic performance simulation of the strengthened structure is checked; and the structural strength of the double-impeller is optimized according to the hydraulic performance simulation checking result.

[0007] Preferably, the parameter data of the original working condition is confirmed, comprising:

[0008] The parameter data of the original working condition is called from the database, including medium characteristic parameters, operation performance parameters, environment parameters and safety parameters;

[0009] The medium characteristic parameters include physical properties, chemical properties and special properties; the operation performance parameters are core performance indexes, power parameters, pressure parameters and temperature parameters; the environment parameters are pit geometry parameters, suction conditions and plant environment parameters; the safety parameters are operation time, extreme working conditions and standard limits;

[0010] The parameter data identification is established at the same time after calling, including data collection time, instrument model and operator;

[0011] The final working condition parameter data is obtained after the parameter data identification.

[0012] Preferably, the performance index definition is performed according to the confirmed working condition parameter data, including:

[0013] The key data in the working condition parameter data is extracted according to the performance index dimension;

[0014] The performance index dimension includes hydraulic performance dimension, structure adaptation dimension, safety redundancy dimension and life dimension.

[0015] The key data in the working condition parameter data is extracted according to the performance index dimension, including anti-wear index and corrosion resistance index; the key data of the operation performance parameters is flow-head curve index, efficiency index, energy consumption index and cavitation performance index; the key data of the environment parameters is structure size index and environmental tolerance index; the key data of the safety parameters is safety redundancy index and life index.

[0016] When the key data in different performance index dimensions conflicts, the conflict is coordinated according to the nuclear safety priority.

[0017] The nuclear safety priority includes first priority, second priority and third priority, wherein the first priority is the key data of the safety parameters; the second priority is the key data of the operation performance parameters; and the third priority is the key data of the environment parameters.

[0018] The performance index data of the working condition parameter data is obtained after the conflict coordination.

[0019] Preferably, the material is designed and selected according to the working condition parameter data and the performance index, including:

[0020] The working condition parameter data and the performance index are cross-mapped, and the constraint conditions of the material are determined according to the cross-mapping result, including medium characteristic constraints and performance index constraints.

[0021] According to the constraint condition, the material category corresponding to the requirement is selected from the nuclear power standard material library, including metal materials and non-metal materials;

[0022] The working condition parameter requirement verification is carried out for the selected material category, and the working condition parameter requirement verification includes corrosion resistance evaluation, wear resistance evaluation and mechanical property evaluation;

[0023] According to the result of the working condition parameter requirement verification, the selected material category is optimized, including multi-material composite and heat treatment strengthening;

[0024] The optimized material is subjected to nuclear safety verification again, and the nuclear safety verification includes material tracing, material certification and irradiation aging simulation;

[0025] The material of the design selection is obtained after the nuclear safety verification is completed and passed.

[0026] Preferably, the basic flow channel structure of the double-flow impeller is constructed according to the performance index, and a flow channel three-dimensional model is constructed according to the basic flow channel structure, including:

[0027] The performance index is converted into constraint conditions of flow channel geometric parameters, including flow rate-lift constraint, efficiency constraint and wear resistance constraint;

[0028] According to the constraint conditions of the flow channel geometric parameters, an initial geometric framework of the double-flow impeller is created, wherein the basic size parameters of the impeller are first confirmed, including the impeller outer diameter, the inlet diameter and the outlet width, then the impeller is divided into two symmetrical flow channels, each of which bears 50% of the flow, and the flow channel spacer tongue is designed in a streamline shape, and finally a logarithmic spiral or an equiangular spiral is used as a blade bone line, wherein the number of blades is 4-6 pieces;

[0029] The created initial geometric framework is analyzed and optimized by fluid dynamics, wherein the initial geometric framework is first imported into the fluid dynamics software for two-dimensional flow channel section generation, and the boundary conditions are set, the velocity distribution of the fluid in the flow channel is simulated according to the generated two-dimensional flow channel section, at the same time, the blade inlet angle is adjusted according to the simulation, and then the pressure distribution in the flow channel is analyzed, and the length and fluid velocity of the flow channel are optimized according to the velocity and pressure analysis in the flow channel;

[0030] According to the optimization result, a three-dimensional model is constructed, wherein the optimization result is imported into a three-dimensional construction tool to generate a blade surface, and then the blade is combined with the hub and the cover plate, after the combination is completed, one flow channel is copied and rotated by 180° to form a symmetrical double-flow structure, and then the symmetrical double-flow structure is verified for double-flow consistency, wherein the area deviation is ≤±2%;

[0031] The three-dimensional model is constructed to obtain a flow channel three-dimensional model.

[0032] Preferably, the hydraulic performance of the initial impeller under the set working condition is analyzed by using the flow passage three-dimensional model, including:

[0033] The fluid calculation is performed by taking the flow passage three-dimensional model as the core, including the impeller inlet section, the impeller rotating domain, and the transition section from the impeller outlet to the volute inlet;

[0034] The flow path of the fluid is obtained after the fluid calculation, and the structured network and the unstructured network are used for meshing the flow path, wherein the boundary layer mesh is arranged on the blade surface and the flow passage wall surface;

[0035] The basic parameters of the set working condition are input, including the inlet condition, the outlet condition, and the rotating condition, the boundary condition is defined according to the basic parameters of the set working condition, including the inlet boundary, the outlet boundary, the wall boundary, and the rotating domain setting;

[0036] The turbulence model is confirmed according to the medium flow characteristics, the turbulence model is the SST k-omega model, and the parameters of the solver are set after the model selection is completed;

[0037] The defined boundary condition and the meshed grid are input into the model for core parameter calculation, wherein the basic performance parameter calculation is performed first, including the head calculation, the efficiency calculation, and the energy consumption index calculation, the cavitation performance evaluation is performed after the basic performance parameter calculation is completed, and whether the anti-cavitation requirement is met is determined according to the cavitation performance evaluation result;

[0038] The hydraulic performance core index analysis is performed according to the calculated core parameters, including the velocity field analysis, the pressure field analysis, the efficiency analysis, and the energy consumption analysis;

[0039] Finally, the hydraulic performance core index analysis result is analyzed to generate a report.

[0040] Preferably, the impeller and the volute are matched according to the hydraulic performance analysis result, and the shape of the blade is optimized, including:

[0041] The synergy problem of the impeller and the volute in the hydraulic performance analysis result is identified, including the flow distribution imbalance, the pressure fluctuation, the backflow, the vortex, and the efficiency loss;

[0042] At the same time, the blade performance defects are marked according to the hydraulic performance analysis result, including the inlet impact, the outlet wake, the flow passage vortex, and the cavitation risk;

[0043] According to the identified impeller and volute coordination problem, the impeller and volute are matched and optimized, wherein the matching and optimization is to match and optimize the inlet position, angle and area ratio, then optimize the gap between the impeller and volute, and finally verify the effect of the optimized impeller and volute, wherein the qualified verification index is that the pressure jump gradient is less than or equal to 0.05 MPa / m, the backflow area ratio is less than or equal to 3%, and the efficiency is increased by more than 2%;

[0044] According to the labeled blade performance defects, the blade shape is designed, including inlet section optimization, middle section optimization, wrap angle optimization, outlet section optimization, tail edge optimization and symmetry calibration, wherein the inlet section optimization is inlet angle adjustment and inlet pre-rotation control; the middle section optimization is flow passage diffusion adjustment; the outlet section optimization is outlet angle and thickness adjustment; and the tail edge optimization is pressure surface and suction surface profile correction;

[0045] Finally, the matching of the impeller and volute, and the optimization of the blade shape are completed.

[0046] Preferably, the structure of the matched and optimized impeller, volute and blade is strengthened, including:

[0047] The strengthened parts are positioned according to the matched and optimized impeller, volute and blade, including high stress concentration area, high wear risk area, anti-shock weak point and extreme working condition sensitive area;

[0048] The strengthening scheme is formulated according to the positioned strengthened parts, wherein the strengthening scheme of the high stress concentration area includes blade root strengthening, impeller cover plate strengthening and volute tongue strengthening; the strengthening scheme of the volute tongue strengthening includes blade inlet leading edge strengthening, flow passage turning strengthening and volute diffusion section inner wall strengthening; the strengthening scheme of the anti-shock weak point includes impeller and shaft connection strengthening and volute support structure strengthening; and the strengthening scheme of the extreme working condition sensitive area includes high temperature deformation control and anti-radiation aging strengthening;

[0049] The performance compatibility verification is performed according to the formulated strengthening scheme, including hydraulic performance review, structural strength verification and anti-wear effect verification;

[0050] The structure of the impeller, volute and blade after the performance compatibility verification is completed and qualified is obtained.

[0051] Preferably, the hydraulic performance simulation review is performed on the strengthened structure, including:

[0052] The three-dimensional model of the strengthened impeller, volute and blade is constructed by using a three-dimensional model construction tool;

[0053] According to the grid division strategy of the combination of structured networks and unstructured networks, the constructed three-dimensional model is locally encrypted, and meanwhile, through three rounds of grid encryption, the calculation results of the head and efficiency under different grid scales are compared, and when the change of the calculation results is less than or equal to 1%, the final grid scale is determined;

[0054] After the grid scale is confirmed, hydraulic performance analysis is performed again, wherein the hydraulic performance analysis is the hydraulic performance analysis after the structure is strengthened;

[0055] The hydraulic performance analysis results before and after the structure is strengthened are compared and analyzed, the comparison and analysis is a performance comparison table before and after the strengthening, including hydraulic parameters, flow field parameters and loss parameters, and then the cause positioning is performed according to the comparison and analysis results;

[0056] According to the analysis results and the causes, a check report is generated.

[0057] Preferably, according to the hydraulic performance simulation check results, the double-impeller structural strength is optimized, including:

[0058] According to the hydraulic performance simulation check results, the key parameters in the analysis results are screened, and the key parameters are pressure load data, flow velocity and centrifugal force correlation data, extreme working condition load and flow field induced vibration data;

[0059] According to the screened key parameters, a structural strength analysis model is constructed, and the constructed structural strength analysis model is analyzed by using the finite element analysis method to analyze the stress, deformation and fatigue life of the impeller under each working condition, including static strength analysis, fatigue strength analysis, vibration modal analysis and extreme working condition strength verification;

[0060] According to the strength weak point analysis results, a structural strength optimization scheme is formulated, including high stress area optimization, deformation exceeding adjustment, fatigue life strengthening and resonance risk elimination;

[0061] Finally, the formulated structural strength optimization scheme is verified for strength compatibility, including hydraulic performance review, strength performance verification and extreme working condition verification.

[0062] Compared with the prior art, the beneficial effects of the present application are as follows:

[0063] 1. The nuclear island pit pump double-flow channel impeller hydraulic design method provided by the present application realizes the comprehensiveness and traceability of data through the innovation of full-process working condition parameter confirmation and performance index definition, retrieves multi-dimensional parameters from a database and establishes an identifier, ensures that the source data is reliable, handles index conflicts according to nuclear safety priorities, clearly defines design targets, provides accurate basis for material selection and flow channel design, reduces design errors caused by parameter deviation, improves the scientificity and pertinence of nuclear island pit pump design, and guarantees equipment performance compliance from the source.

[0064] 2. The nuclear island pit pump double-flow impeller hydraulic design method provided by the present application, the double-flow impeller design and hydraulic performance optimization innovation significantly improves the operation efficiency and stability, the symmetrical flow channel equally divides the flow, the streamline type spacer reduces the resistance, the fluid dynamics simulation optimizes the flow field, reduces the vortex and hydraulic loss; three-dimensional modeling and meshing ensure accurate analysis, effectively reduce the risk of cavitation, impeller and volute matching and blade optimization further improve the efficiency, so that the equipment runs efficiently and stably under the complex working conditions of the nuclear island.

[0065] 3. The nuclear island pit pump double-flow impeller hydraulic design method provided by the present application, the synergistic innovation of structure strengthening and strength optimization takes into account safety and durability, accurately locates weak parts such as high stress areas, and develops targeted strengthening schemes; through finite element analysis and compatibility verification, the structure strength is improved while the hydraulic performance is ensured, extreme condition verification ensures that the equipment can resist the influence of radiation, high temperature, etc., prolongs the service life, meets the needs of high safety and long period operation of the nuclear island, and realizes the balance between strength and performance. BRIEF DESCRIPTION OF DRAWINGS

[0066] Figure 1 The figure is a schematic diagram of the nuclear island pit pump double-flow impeller hydraulic design process of the present application. DETAILED DESCRIPTION

[0067] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0068] In order to solve the problems in the prior art that the working condition parameters are not complete, there is no identification and it is difficult to trace; the performance index is not accurate, and there is no nuclear safety priority in conflict processing; the material selection and working condition performance are not matched, and there is a lack of nuclear safety verification, please refer to Figure 1 The present embodiment provides the following technical solutions:

[0069] The nuclear island pit pump double-flow impeller hydraulic design method comprises:

[0070] The parameter data of the original working condition is confirmed first; the performance index is defined according to the confirmed working condition parameter data; the material is selected according to the working condition parameter data and the performance index; the basic flow channel structure of the double-flow channel impeller is constructed according to the performance index, and the three-dimensional model of the flow channel is constructed according to the basic flow channel structure; the hydraulic performance of the initial impeller under the set working condition is analyzed by using the three-dimensional model of the flow channel; the impeller and the volute are matched according to the hydraulic performance analysis result, and the shape of the blade is optimized; the structure of the matched and optimized impeller, volute and blade is strengthened; the hydraulic performance of the strengthened structure is simulated and checked; and the structural strength of the double-impeller is optimized according to the hydraulic performance simulation and checking result.

[0071] Specifically, the confirmation of the original working condition parameter data is the basis of the entire design, which ensures the accuracy of the initial design data, provides a reliable basis for the subsequent links, avoids design errors caused by parameter deviation from the source, reduces the probability of rework, improves the design efficiency, defines the performance index according to the confirmed working condition parameters, makes the design target clear, and provides a clear guide for the impeller design, which can accurately meet the actual operation requirements of the nuclear island pit pump, ensure that the performance of the final product meets the standard, and enhance the pertinence and effectiveness of the design. Combined with the working condition parameters and the performance index, the selected material can adapt to the complex and harsh working environment of the nuclear island, has sufficient strength, corrosion resistance and stability, prolongs the service life of the impeller, reduces the risk of equipment failure, and ensures the long-term reliable operation of the pump. The construction of the double-flow channel basic flow channel structure and the establishment of the three-dimensional model can effectively improve the anti-cavitation performance and running stability of the pump. The three-dimensional model provides an intuitive and accurate carrier for subsequent analysis, which facilitates detailed research on the flow inside the flow channel and helps to optimize the flow channel design. The three-dimensional model can be used to analyze the hydraulic performance of the initial impeller, which can help to identify problems at an early stage of design, make timely adjustments, avoid losses caused by defects found after manufacturing, reduce design costs, and provide data support for subsequent optimization, thereby improving the scientific nature of the design. According to the analysis results, the impeller and the volute are matched, and the shape of the blade is optimized, which can improve the flow state of the fluid in the pump, reduce hydraulic loss, improve the efficiency of the pump, and enhance the running stability, so that the pump can perform better under the set working condition. The optimized structure is strengthened, which can improve the overall strength and stiffness of the impeller, so that it can withstand various loads and impacts under the working condition of the nuclear island, improve the safety of the equipment, and meet the high reliability requirements of the nuclear island. The strengthened structure is subjected to hydraulic performance simulation and checking, which can comprehensively test the optimization effect and ensure the stable performance of the impeller under various working conditions. The rationality of the design is further verified, the risk in actual operation is reduced, and the structural strength of the impeller is optimized according to the simulation and checking result, which balances the hydraulic performance and structural strength, makes the impeller structure more reasonable, prolongs the service life, and improves the overall performance and safety and reliability of the nuclear island pit pump.

[0072] The parameter data of the original working condition is confirmed, including:

[0073] The parameter data of the original working condition is retrieved from the database, including medium characteristic parameters, operation performance parameters, environmental parameters and safety parameters;

[0074] The medium characteristic parameters include physical properties, chemical properties and special properties; the operation performance parameters are core performance indicators, power parameters, pressure parameters and temperature parameters; the environmental parameters are pit geometry parameters, suction conditions and plant environmental parameters; the safety parameters are operation time, extreme working conditions and standard limits;

[0075] After retrieval, parameter data identification is established, including data collection time, instrument model and operator;

[0076] After parameter data identification, the final working condition parameter data is obtained.

[0077] Specifically, multi-dimensional parameters are retrieved from the database, covering medium characteristics, operation performance, environment and safety parameters, realizing the comprehensiveness of data collection. The subdivided parameters of medium characteristics can accurately reflect the essential properties of the conveying medium, the operation performance parameters directly hit the core operation indicators, the environmental parameters are consistent with the actual scene of the pit, and the safety parameters guarantee the reliability under extreme working conditions. Multiple parameters provide panoramic data support for design, avoid design deviation caused by information loss, medium characteristics are divided according to physical, chemical and special properties, operation performance clearly indicates core indicators and power, pressure and other parameters, environmental parameters are refined to pit geometry and suction conditions, and safety parameters focus on operation time and extreme working conditions. This structured classification enables designers to quickly locate key data, improves parameter calling efficiency, ensures accurate matching of design links and actual working conditions, records collection time, instrument model and operator, and builds a complete data traceability chain, which facilitates subsequent verification of data effectiveness. When problems occur in design or operation, the data collection process can be traced back through the identification information to identify the source of errors, provide a basis for data correction and responsibility definition, improve the standardization of data management, and finally the working condition parameter data is identified to significantly improve the reliability of the data. Through multi-link verification, invalid or incorrect data is eliminated to ensure that the parameters input into the design link are real and effective, reducing the risk of design caused by data distortion from the source, laying a solid foundation for subsequent material selection, flow channel design and other links, and ensuring the scientificity and accuracy of the entire water conservancy design process. Through systematic data collection, classification and verification, a closed-loop parameter confirmation mechanism is formed, which not only meets the stringent requirements of nuclear island equipment for data accuracy, but also provides reliable protection for efficient promotion of the entire design process.

[0078] According to the confirmed working condition parameter data, the performance indicators are defined, including:

[0079] According to the performance indicator dimension, the key data in the working condition parameter data is extracted;

[0080] The performance index dimension includes a hydraulic performance dimension, a structure adaptation dimension, a safety redundancy dimension, and a service life dimension.

[0081] The medium characteristic parameters in the working condition parameter data are subjected to key data extraction according to the performance index dimension, including an anti-wear index and a corrosion resistance index; the key data of the operating performance parameters are a flow-head curve index, an efficiency index, an energy consumption index, and a cavitation performance index; the key data of the environmental parameters are a structure size index and an environmental tolerance index; and the key data of the safety parameters are a safety redundancy index and a service life index.

[0082] When the key data in different performance index dimensions are in conflict, the conflict is coordinated according to a nuclear safety priority.

[0083] The nuclear safety priority includes a first priority, a second priority, and a third priority, wherein the first priority is the key data of the safety parameters; the second priority is the key data of the operating performance parameters; and the third priority is the key data of the environmental parameters.

[0084] The performance index data of the working condition parameter data are obtained after the conflict is coordinated.

[0085] Specifically, the key data are extracted in multiple dimensions, covering the hydraulic performance, the structure adaptation, the safety redundancy, and the service life dimension, so that the performance index system is comprehensive and systematic, the key elements for the operation of the nuclear island pit pump are avoided to be omitted, the index can comprehensively reflect the equipment operation requirements, complete guidance is provided for subsequent design, the key data are accurately extracted for different parameter types, such as the medium characteristic focuses on the anti-wear and corrosion resistance indexes, and the operating performance locks the core indexes such as the flow-head curve, the performance index is closely related to the actual working condition, the accuracy and practicality of the index are improved, the design is ensured to be closely related to the core requirements of the equipment operation, the conflict coordination mechanism of the nuclear safety priority is established, the key data of the safety parameters are listed as the first priority, and the principle of nuclear safety first is highlighted. When the data conflict, the safety index is prioritized to ensure that the design does not deviate from the high safety standard of the nuclear facility, the safety bottom line of the equipment operation is fundamentally ensured, the data contradiction is solved through the clear priority order, the subjectivity and randomness are avoided, the performance index data are more scientific and reasonable, the final index can meet the multi-dimensional requirements and make the optimal choice in conflict, the reliability of the index is enhanced, the whole process forms a closed loop from data extraction to conflict processing, the final performance index data have both comprehensiveness and emphasis, the requirements of the equipment operation in all aspects are covered, the safety and core performance are highlighted, high-quality index basis is provided for subsequent material selection, structure design, and other links, and the scientificity and effectiveness of the overall design are improved. The corresponding relationship between the working condition parameter data and the performance index in the definition of the performance index related parameters is shown in the following table.

[0086]

[0087]

[0088] According to the working condition parameter data and the performance index, the material is designed and selected, including:

[0089] The working condition parameter data and the performance index are cross-mapped, and the constraint conditions of the material are determined according to the cross-mapping result, including medium characteristic constraints and performance index constraints;

[0090] According to the constraint conditions, the material category corresponding to the requirements is selected from the nuclear power standard material library, including metal materials and non-metal materials;

[0091] The working condition parameter requirement verification is carried out for the selected material category, and the working condition parameter requirement verification includes corrosion resistance evaluation, wear resistance evaluation and mechanical property evaluation;

[0092] According to the result of the working condition parameter requirement verification, the selected material category is optimized, including multi-material compounding and heat treatment strengthening;

[0093] The optimized material is subjected to nuclear safety verification again, and the nuclear safety verification includes material tracing, material certification and irradiation aging simulation;

[0094] The material of the design selection is completed after the nuclear safety verification is completed and passed.

[0095] Specifically, by cross-mapping the working condition parameters and performance indicators to determine the constraint conditions, the material selection has a precise basis, and the medium characteristic constraint and the performance indicator constraint work together to ensure that the material characteristics are highly matched with the operation requirements of the nuclear island pit pump, avoid equipment failures caused by inconsistent material characteristics, improve the pertinence of material selection, and the nuclear power standard material is strictly certified to meet the basic safety requirements of nuclear facilities on materials, reduce the potential risks brought by non-standard materials, and lay a solid safety foundation for subsequent use. The working condition parameter verification link comprehensively evaluates the corrosion resistance, wear resistance and mechanical properties of the material, which can identify unqualified materials through targeted verification in advance to ensure that the selected material maintains stable performance in long-term operation and prolongs the service life of the equipment. The optimization mode of multi-material composite and heat treatment can integrate the advantages of different materials, such as composite materials that can balance corrosion resistance and wear resistance, and heat treatment that can improve mechanical strength, making the material performance more comprehensive and meeting the multiple requirements of the nuclear island complex working conditions. The nuclear safety verification link ensures the nuclear safety adaptability of the material through material tracing, certification and irradiation aging simulation. Especially the irradiation aging simulation can predict the performance changes of the material in the long-term irradiation environment to ensure its stability in extreme working conditions and meet the high safety standards of the nuclear island. The whole process forms a closed loop of "constraint-selection-verification-optimization-re-verification", which controls the material performance and nuclear safety requirements layer by layer, ensuring that the material meets the operation requirements and complies with the nuclear safety specifications, significantly improving the scientificity and reliability of material selection.

[0096] To solve the problems of the prior art, such as the mismatch between the flow channel geometric parameters and performance indicators, poor symmetry, poor grid quality in hydraulic performance analysis, inaccurate parameter calculation leading to unreliable evaluation, poor matching between the impeller and the volute, flow imbalance, and blade inlet impact, resulting in low efficiency, high energy consumption, and high risk of cavitation, please refer to Figure 1 The embodiment provides the following technical solutions:

[0097] According to the performance indicators, a basic flow channel structure of the double-flow impeller is constructed, and a flow channel three-dimensional model is constructed according to the basic flow channel structure, including:

[0098] The performance indicators are converted into constraint conditions of the flow channel geometric parameters, including flow-head constraint, efficiency constraint, and wear resistance constraint;

[0099] According to the constraint conditions of the flow channel geometric parameters, an initial geometric framework of the double-flow impeller is created, wherein the basic size parameters of the impeller are first confirmed, including the impeller outer diameter, the inlet diameter and the outlet width, then the impeller is divided into two symmetrical flow channels, each flow channel bears 50% of the flow, the flow channel spacer tongue is designed in a streamline shape, and finally a logarithmic spiral line or an equiangular spiral line is used as a blade bone line, wherein the number of blades is 4-6;

[0100] The created initial geometric framework is analyzed and optimized by fluid dynamics, wherein the initial geometric framework is first imported into a fluid dynamics software to generate a two-dimensional flow passage section, boundary conditions are set, the velocity distribution of fluid in the flow passage is simulated according to the generated two-dimensional flow passage section, the blade inlet angle is adjusted according to the simulation, the pressure distribution in the flow passage is analyzed, and the length of the flow passage and the fluid velocity are optimized according to the analysis of the velocity and pressure in the flow passage;

[0101] A three-dimensional model is constructed according to the optimization results, wherein the optimization results are imported into a three-dimensional construction tool to generate a blade surface, the blade is combined with a hub and a cover plate, the combined structure is copied and rotated by 180° to form a symmetrical double-flow passage structure, and the symmetrical double-flow passage structure is verified for consistency, wherein the area deviation is ≤±2%;

[0102] The three-dimensional model construction is completed to obtain a flow passage three-dimensional model.

[0103] Specifically, the performance indicators are converted into geometric parameter constraints, so that the flow passage design directly meets the core requirements of flow rate-lift, efficiency and the like, the geometric parameters are closely related to the performance targets, the design is prevented from being disconnected with the actual requirements, the design pertinence and accuracy are improved, the initial geometric framework design is scientific, the symmetrical double-flow passage bears 50% of the flow rate, the load is balanced, and vibration caused by hydraulic unbalance is reduced; the streamlined tongue reduces fluid resistance, the spiral blade skeleton optimizes fluid guidance, the number of 4-6 blades balances efficiency and anti-clogging, the structural stability and operating efficiency are enhanced, the fluid dynamics analysis and optimization link adjusts the blade inlet angle and the flow passage parameters by simulating the velocity and pressure distribution of the two-dimensional section, effectively improves the flow state in the flow passage, reduces vortex and hydraulic loss, improves the hydraulic efficiency of the impeller, avoids potential flow defects in advance, reduces test cost, the three-dimensional model construction process is rigorous, the blade surface generation and component combination are accurate, the symmetrical flow passage is ensured to be symmetrical by 180° copying and rotation, the consistency verification with an area deviation of ≤±2% ensures that the performance of the double-flow passage is balanced, performance fluctuations caused by unsymmetrical flow passage are avoided, a high-precision digital model is provided for subsequent manufacturing, processing errors are reduced, the overall scheme forms a closed loop of "performance constraint-geometric design-fluid optimization-three-dimensional verification", hydraulic performance and structural reliability are considered, the scheme adapts to the harsh requirements of the nuclear island pit pump for high efficiency, stability and wear resistance, and significantly improves the scientificity and engineering practicability of the impeller design.

[0104] The hydraulic performance of the initial impeller under a set working condition is analyzed by using the flow passage three-dimensional model, including:

[0105] Fluid calculation is performed based on the flow passage three-dimensional model, including the impeller inlet section, the impeller rotating domain, and the transition section from the impeller outlet to the volute inlet;

[0106] The fluid calculation obtains a flow path of the fluid, and structured network and unstructured network are used for mesh division of the flow path, wherein boundary layer meshes are arranged on the blade surface and the flow passage wall surface;

[0107] The basic parameters of the set working condition are input, the basic parameters of the set working condition include inlet conditions, outlet conditions and rotating conditions, boundary condition definition is performed according to the basic parameters of the set working condition, including inlet boundary, outlet boundary, wall boundary and rotating area setting;

[0108] The turbulent flow model is confirmed according to the medium flow characteristics, the turbulent flow model is an SST k-ω model, and the parameters of the solver are set after the model selection is completed;

[0109] The defined boundary conditions and the divided meshes are input into the model for core parameter calculation, wherein basic performance parameter calculation is performed first, including head calculation, efficiency calculation and energy consumption index calculation, cavitation performance evaluation is performed after the basic performance parameter calculation is completed, and whether the anti-cavitation requirement is met is judged according to the cavitation performance evaluation result;

[0110] Hydraulic performance core index analysis is performed according to the calculated core parameters, including velocity field analysis, pressure field analysis, efficiency analysis and energy consumption analysis;

[0111] Finally, the hydraulic performance core index analysis result is analyzed to generate a report.

[0112] Specifically, the fluid calculation range is comprehensive, covering the impeller inlet section, the rotating domain, and the outlet to the volute inlet transition section, fully covering the key areas of fluid flow through the impeller, capturing the fluid flow characteristics, avoiding analysis omissions due to limited calculation range, providing complete data support for hydraulic performance evaluation, scientific grid division combining structured and unstructured grids, and setting boundary layer grids on the blade surface and flow passage wall, ensuring calculation efficiency and improving the calculation accuracy of key areas, accurately simulating the flow state of fluid near the wall, reducing the influence of grid division on the analysis results, defining boundary conditions in line with the actual situation, inputting the basic parameters of the working condition, and clearly defining the inlet, outlet, wall, and rotating domain boundary conditions, so that the hydraulic performance analysis is based on the real operating scenario, ensuring that the analysis results are highly consistent with the actual working conditions, improving the reference value of the results, and selecting a reasonable turbulence model. The SST k-omega model takes into account the simulation accuracy of near-wall flow and main flow area, suitable for complex turbulent flow analysis in the impeller, and with the targeted setting of solver parameters, it can accurately calculate core parameters such as head and efficiency, ensuring the reliability of hydraulic performance evaluation, and the analysis content is comprehensive, including basic performance parameter calculation and cavitation performance evaluation, as well as flow field detail analysis such as velocity field and pressure field, which can comprehensively evaluate the performance of the impeller from macro performance to micro flow state, providing a clear direction for subsequent optimization, effectively improving the perfection of the initial impeller design. Through accurate modeling, scientific calculation, and comprehensive analysis, a complete hydraulic performance evaluation system is formed, providing a detailed data and reliable conclusion analysis report for impeller optimization, significantly improving the pertinence and efficiency of design optimization.

[0113] According to the hydraulic performance analysis results, the impeller and volute are matched, and the shape of the blade is optimized, including:

[0114] The synergy problem of the impeller and the volute in the hydraulic performance analysis results is identified, and the synergy problem includes flow distribution imbalance, pressure fluctuation, backflow, vortex, and efficiency loss;

[0115] At the same time, according to the hydraulic performance analysis results, the blade performance defects are marked, including inlet impact, outlet wake, flow passage vortex, and cavitation risk;

[0116] According to the identified synergy problem of the impeller and the volute, the impeller and the volute are matched and optimized, wherein the matching and optimization is to match and optimize the inlet position, angle, and area ratio, and then optimize the gap between the impeller and the volute, and finally verify the effect of the optimized impeller and volute, wherein the qualified verification indicators are pressure jump gradient ≤0.05 MPa / m, backflow area ratio ≤3%, and efficiency improvement ≥2%;

[0117] According to the annotated blade performance defects, the blade shape is designed, including inlet section optimization, middle section optimization, wrap angle optimization, outlet section optimization, tail edge optimization and symmetry calibration, wherein the inlet section optimization is inlet angle adjustment and inlet pre-rotation control; the middle section optimization is flow passage diffusion degree adjustment; the outlet section optimization is outlet angle and thickness adjustment; and the tail edge optimization is pressure surface and suction surface profile correction;

[0118] Finally, the matching of the impeller and the volute and the optimization of the blade shape are completed.

[0119] Specifically, through focusing on specific problems such as flow distribution imbalance and inlet impact, blind adjustment is avoided, the optimization measures directly hit the performance short board, the rectification efficiency is improved, the invalid design cost is reduced, the matching optimization system of the impeller and the volute is improved, from the inlet parameters to the gap adjustment, and the quantitative verification index is set. The hard indexes such as pressure sudden change gradient and backflow area ratio ensure that the optimization effect is measurable and controllable, the efficiency improvement of ≥2% directly points to the performance improvement, so that the matching effect has stability and economy, the blade shape design covers the whole process optimization, the inlet section adjustment reduces the impact loss, the middle section diffusion degree optimization improves the flow uniformity, the outlet section and the tail edge correction reduce the wake effect, multi-dimensional optimization cooperates to improve the hydraulic performance of the blade, and the symmetry calibration guarantees the consistency of the double flow passage performance, adapts to the high stability demand of the nuclear island equipment, verifies the optimization results through quantitative indexes, avoids "pseudo-optimization", and ensures that the adjusted impeller and volute have small pressure fluctuation, less backflow, high efficiency, enhanced blade anti-cavitation and wear resistance, and prolonged equipment life.

[0120] In order to solve the problems of low hydraulic efficiency, high cavitation risk, poor matching of impeller and volute, structure easy to fail due to high stress, wear and corrosion, insufficient adaptability to extreme working conditions in the prior art, please refer to Figure 1 The embodiment provides the following technical solutions:

[0121] According to the matched and optimized impeller, volute and blade, structure strengthening is performed, including:

[0122] According to the matched and optimized impeller, volute and blade, the strengthening position is positioned, including a high stress concentration area, a high wear risk area, an anti-seismic weak point and an extreme working condition sensitive area;

[0123] According to the positioned strengthening position, a strengthening scheme is formulated, wherein the strengthening scheme of the high stress concentration area includes blade root strengthening, impeller cover plate strengthening and volute tongue strengthening; the strengthening scheme of the volute tongue strengthening includes blade inlet leading edge strengthening, flow passage turning strengthening and volute diffusion section inner wall strengthening; the strengthening scheme of the anti-seismic weak point includes impeller and shaft connection strengthening and volute support structure strengthening; and the strengthening scheme of the extreme working condition sensitive area includes high temperature deformation control and anti-radiation aging strengthening.

[0124] According to the formulated strengthening scheme, performance compatibility verification is carried out, including hydraulic performance review, structural strength verification and anti-wear effect verification;

[0125] After the performance compatibility verification is completed and qualified, the impeller, volute and blade after structural strengthening are obtained.

[0126] Specifically, the strengthening position is accurately positioned, focusing on key areas such as high stress concentration area and high wear risk area, avoiding resource waste caused by indiscriminate strengthening, making the strengthening measures directly hit the weak points of the structure, improving the strengthening efficiency, and ensuring that each strengthening work can solve the potential failure risk, the strengthening scheme is targeted, and different measures are taken according to different regional characteristics. For example, the blade root and cover plate are strengthened in the high stress concentration area, the connection and support structure are strengthened in the weak shock resistance area, and high temperature and radiation protection are focused on in the extreme working condition sensitive area. This way of classified measures can maximize the resistance of the structure under certain risks and enhance the overall stability. The performance compatibility verification link is comprehensive, the hydraulic performance review ensures that the strengthening does not affect the optimized fluid dynamic characteristics, the structural strength verification ensures that the strengthening effect meets the standard, and the anti-wear effect verification confirms the effect of the strengthening on prolonging the service life. Multi-dimensional verification avoids performance imbalance caused by strengthening, realizes the coordinated improvement of structural strength and hydraulic performance, and controls the high temperature deformation of the extreme working condition sensitive area and the anti-radiation aging strengthening. It is specially designed for the special environment of the nuclear island, which can effectively resist the influence of long-term irradiation and temperature fluctuation, meet the strict requirements of nuclear safety on long-term reliable operation of equipment, and form a closed loop of "accurate positioning-targeted strengthening-comprehensive verification". It not only consolidates the performance results of the previous matching optimization, but also improves the safety redundancy and service life of the equipment through structural strengthening, and has scientificity and engineering practicality, which provides a solid guarantee for the stable operation of the nuclear island pit pump.

[0127] The hydraulic performance simulation review of the strengthened structure includes:

[0128] A three-dimensional model construction tool is used to construct a three-dimensional model of the impeller, volute and blade after strengthening;

[0129] According to the grid division strategy of the combination of structured network and unstructured network, the constructed three-dimensional model is locally encrypted, and at the same time, through 3 rounds of grid encryption, the calculation results of head and efficiency under different grid scales are compared, and when the calculation result change is ≤1%, the final grid scale is determined;

[0130] After the grid scale is confirmed, hydraulic performance analysis is performed again, wherein the hydraulic performance analysis is the hydraulic performance analysis after structural strengthening;

[0131] The hydraulic performance analysis results before and after the structure strengthening are compared and analyzed, a performance comparison table before and after the strengthening is established, including hydraulic parameters, flow field parameters and loss parameters, and the cause is located according to the comparison and analysis results;

[0132] A check report is generated according to the analysis results and the cause.

[0133] Specifically, the three-dimensional model accurately restores the structural characteristics after the strengthening, providing a high-fidelity geometric carrier for simulation. By accurately mapping the size and shape of the strengthened parts, the detailed features of key structures such as blades and volutes are completely preserved, avoiding calibration deviations caused by model distortion, and laying a reliable foundation for subsequent flow field analysis, ensuring the authenticity of the calibration results from the source, and combining structured and unstructured grids to adapt to complex flow channel morphology. Local encryption of blade surfaces and flow channel walls can accurately capture near-wall flow details; 3 rounds of grid encryption verification until the calculation result changes ≤1%, grid independence test is performed to eliminate the influence of grid size on the results, ensuring stable and reliable calculation of core parameters such as head and efficiency, reducing numerical error interference, and establishing a comparison table covering hydraulic parameters (head, efficiency), flow field parameters (velocity distribution, pressure gradient), and loss parameters (hydraulic loss, local vortex loss) to quantitatively evaluate the impact of strengthening measures on performance. For example, if the backflow area loss decreases by 30% after strengthening, it can be directly related to the flow channel optimization effect, realizing accurate tracing of "measure-phenomenon-result", providing data support for structural improvement. In the comparative analysis, not only the changes in performance indicators are focused on, but also the root causes are traced back through the differences in flow field parameters, such as the intensification of pressure fluctuations may be due to the flow channel mutation at the strengthened site, thereby guiding subsequent structural fine-tuning. This "result-driven-cause" logic loop avoids the performance imbalance caused by blind strengthening, ensuring that the structural strengthening improves the strength while not compromising the hydraulic efficiency. From model construction to grid verification, to performance comparison and cause analysis, each step is supported by traceable quantitative data, meeting the stringent requirements of nuclear island equipment for safety and reliability. The report not only verifies the effectiveness of the strengthening measures, but also provides a clear direction for subsequent iterative optimization, realizing the continuous improvement of "strengthening-verification-improvement", and balancing the structural strength and hydraulic performance.

[0134] According to the hydraulic performance simulation check results, the double-impeller structural strength is optimized, including:

[0135] According to the hydraulic performance simulation check results, the key parameters in the analysis results are screened, the key parameters are pressure load data, flow velocity and centrifugal force correlation data, extreme working condition load and flow field induced vibration data;

[0136] According to the key parameters of the screening, a structural strength analysis model is constructed, and the stress, deformation and fatigue life of the impeller under each working condition are analyzed by using the finite element analysis method, including static strength analysis, fatigue strength analysis, vibration modal analysis and extreme condition strength verification.

[0137] According to the results of the structural strength weak point analysis, a structural strength optimization scheme is developed, including high stress area optimization, deformation adjustment, fatigue life strengthening and resonance risk elimination.

[0138] Finally, the structural strength optimization scheme is verified for strength compatibility, including hydraulic performance review, strength performance verification and extreme condition verification.

[0139] Specifically, by extracting key parameters such as pressure load, flow rate and centrifugal force correlation data, and eliminating redundant information, the structural strength analysis is directly connected to the hydraulic performance review results, avoiding irrelevant data interference. This precise screening not only reduces the amount of calculation, but also ensures that each analysis is closely related to the nature of the impeller stress, laying a reliable data foundation for subsequent strength optimization, meeting the stringent requirements of nuclear island equipment for analysis accuracy, and using finite element analysis to construct a model, simultaneously carrying out static strength, fatigue strength, vibration modal and extreme condition verification, achieving full-scene coverage from normal operation to extreme conditions. For example, vibration modal analysis can identify resonance risks in advance, and extreme condition verification simulates the structural response under accident conditions, capturing weak points in strength from all angles, avoiding the risk of missing single working condition analysis, and developing measures for specific problems such as high stress area optimization and deformation adjustment. For example, the high stress area at the root of the blade is optimized with a rounded transition, and support structures are added to areas with excessive deformation, so that each optimization action directly corresponds to the weak point of strength. This precise matching of "problem-solution" avoids the waste of resources caused by blind strengthening, significantly improves the balance of structural strength, and ensures that strength optimization does not damage the flow passage shape and hydraulic efficiency through hydraulic performance review, confirms the effectiveness of optimization measures through strength performance verification, and verifies the structural stability under extreme conditions. This multi-dimensional verification avoids the optimization trap of "gaining one and losing the other", realizes the coordinated improvement of structural strength and hydraulic performance, and meets the dual requirements of high efficiency and safety of nuclear island sump pumps. From the hydraulic performance review results to the structural strength requirements, and then through the strength optimization feedback of hydraulic performance compatibility, a closed-loop logic of "hydraulic-strength" two-way verification is formed. This design idea not only guarantees the structural stability of the impeller in a complex flow field, but also maintains its high-efficiency hydraulic characteristics, providing key technical support for long-term reliable operation of nuclear island equipment.

[0140] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting, since the scope of the present application will be limited to the appended claims. It must be noted that, as used in the specification and the appended claims, the singular form "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component" can include a plurality of components. Similarly, the words "comprise," "comprises," and "comprising," as well as the words "include," "includes," and "including," when used in this specification and in the following claims, are intended to specify the presence of stated features, regions, integers, steps, operations, elements, or components, but they do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, or groups thereof. Furthermore, these terms do not necessarily denote the presence of anything that can be claimed as new. The meaning of "a," "an," and "the" also includes plural references and plural forms, for example, "a" or "an" entity includes one or more entities.

[0141] While the embodiments of the application have been shown and described herein, it is understood that modifications, substitutions, changes, and alterations can be made by those skilled in the art without departing from the spirit and scope of the present application.

Claims

1. A method for hydraulic design of a double channel impeller for a nuclear island sump pump, characterized in that, include: First, confirm the parameter data of the original working condition; then define the performance indicators based on the confirmed working condition parameter data. Material selection is based on operating condition parameters and performance indicators. Based on the performance indicators, the basic flow channel structure of the dual-flow channel impeller is constructed, and a three-dimensional model of the flow channel is constructed based on the basic flow channel structure. The hydraulic performance of the initial impeller under set operating conditions was analyzed using a three-dimensional flow channel model; the impeller and volute were matched based on the hydraulic performance analysis results, and the blade shape was optimized; the structure was strengthened based on the matched and optimized impeller, volute, and blades. The hydraulic performance of the reinforced structure was verified by simulation. The strength of the double impeller structure was optimized based on the hydraulic performance simulation verification results; Based on performance indicators, the basic flow channel structure of the dual-flow-channel impeller is constructed, and a three-dimensional model of the flow channel is built based on the basic flow channel structure, including: The performance indicators are converted into constraints on the flow channel geometry parameters, including flow-head constraints, efficiency constraints, and wear resistance constraints. Based on the constraints of the flow channel geometry parameters, an initial geometric framework for a dual-flow channel impeller is created. First, the basic dimensional parameters of the impeller are determined, including the impeller outer diameter, inlet diameter, and outlet width. Then, the impeller is divided into two symmetrical flow channels, each of which handles 50% of the flow. The flow channel tongue adopts a streamlined design. Finally, a logarithmic spiral or an equiangular spiral is used as the blade rib, with 4-6 blades. The initial geometric framework was analyzed and optimized using fluid dynamics. First, the initial geometric framework was imported into fluid dynamics software to generate a two-dimensional flow channel cross-section and set boundary conditions. The velocity distribution of the fluid in the flow channel was simulated based on the generated two-dimensional flow channel cross-section. At the same time, the blade inlet angle was adjusted according to the simulation results. Then, the pressure distribution in the flow channel was analyzed. Based on the velocity and pressure analysis results in the flow channel, the length of the flow channel and the fluid velocity were optimized. Based on the optimization results, a three-dimensional model is constructed. The optimization results are imported into a three-dimensional construction tool to generate blade surfaces. Then, the blades are combined with the hub and cover plate. After the combination is completed, a flow channel is copied and rotated 180° to form a symmetrical dual-flow channel structure. The consistency of the dual-flow channel structure is then verified. The verification area deviation is within ≤±2%. After the 3D model is constructed, the flow channel 3D model is obtained.

2. The nuclear island pit pump double passage impeller hydraulic design method according to claim 1, characterized in that, Confirm the parameter data of the original operating conditions, including: Retrieve the original operating condition parameter data from the database, including media characteristic parameters, operating performance parameters, environmental parameters, and safety parameters; The medium characteristic parameters include physical properties, chemical properties, and special properties; the operating performance parameters are core performance indicators, power parameters, pressure parameters, and temperature parameters; the environmental parameters are sump geometry parameters, suction conditions, and plant environment parameters; and the safety parameters are operating time, extreme operating conditions, and standard limits. After the data is retrieved, a parameter data identifier is created, which includes the data acquisition time, instrument model, and operator. The final operating condition parameter data is obtained after the parameter data is identified.

3. The nuclear island pit pump double passage impeller hydraulic design method according to claim 2, characterized in that, Performance indicators are defined based on the confirmed operating condition parameter data, including: Based on performance indicators, key data are extracted from the operating condition parameter data; Among them, the performance indicators include hydraulic performance, structural adaptation, safety redundancy, and lifespan. Based on the performance index dimension, key data of medium characteristic parameters in the operating condition parameter data are extracted, including wear resistance index and corrosion resistance index; key data of operating performance parameters are flow-head curve index, efficiency index, energy consumption index and cavitation performance index; key data of environmental parameters are structural dimension index and environmental tolerance index; key data of safety parameters are safety redundancy index and life index. When there are conflicts in key data across different performance metrics, conflict coordination should be carried out based on nuclear safety priorities. Nuclear safety priorities include first priority, second priority, and third priority. First priority refers to key data of safety parameters; second priority refers to key data of operational performance parameters; and third priority refers to key data of environmental parameters. Performance index data obtained after conflict coordination, including operating condition parameter data.

4. The nuclear island pit pump double passage impeller hydraulic design method according to claim 3, characterized in that, Material selection is based on operating condition parameters and performance indicators, including: Cross-mapping is performed on operating condition parameter data and performance indicators, and the constraints on the material, including medium characteristic constraints and performance indicator constraints, are determined based on the cross-mapping results. Based on the constraints, select the corresponding material categories from the nuclear power standard material library, including metallic and non-metallic materials; For the selected material category, the operating condition parameter requirements are verified, including corrosion resistance assessment, wear resistance assessment, and mechanical property assessment. Based on the verification results of the working condition parameter requirements, the selected material categories are optimized, including multi-material composites and heat treatment strengthening. The optimized materials will undergo nuclear safety verification again, which includes material traceability, material certification, and irradiation aging simulation. After nuclear safety verification is completed and passed, the materials selected for the design are obtained.

5. The nuclear island pit pump double passage impeller hydraulic design method according to claim 4, characterized in that, The hydraulic performance of the initial impeller under set operating conditions was analyzed using a three-dimensional flow channel model, including: Fluid calculations are performed using a three-dimensional flow channel model as the core, including the impeller inlet section, the impeller rotation domain, and the transition section from the impeller outlet to the volute inlet. After fluid calculation, the flow path of the fluid is obtained. Then, structured and unstructured networks are used to mesh the flow path. Boundary layer meshes are set on the blade surface and the flow channel wall. Input the basic parameters of the set working condition, which include inlet conditions, outlet conditions, and rotation conditions. Define the boundary conditions based on the basic parameters of the set working condition, including inlet boundary, outlet boundary, wall boundary, and rotation domain settings. The turbulence model was confirmed based on the flow characteristics of the medium. The turbulence model was SSTk-ω. After the model was selected, the parameters of the solver were set. The defined boundary conditions and the divided mesh are input into the model for core parameter calculation. First, the basic performance parameters are calculated, including head, efficiency and energy consumption index. After the basic performance parameters are calculated, the cavitation performance is evaluated, and the cavitation performance evaluation results are used to determine whether the anti-cavitation requirements are met. Based on the calculated core parameters, the core hydraulic performance indicators are analyzed, including velocity field analysis, pressure field analysis, efficiency analysis, and energy consumption analysis. Finally, the analysis results of the core hydraulic performance indicators are used to generate an analysis report.

6. The nuclear island pit pump double passage impeller hydraulic design method according to claim 5, characterized in that, Based on the hydraulic performance analysis results, the impeller and volute are matched, and then the blade shape is optimized, including: The collaborative problems between the impeller and the volute in the hydraulic performance analysis results are identified. These collaborative problems include flow distribution imbalance, pressure fluctuation, backflow, vortex and efficiency loss. Meanwhile, based on the hydraulic performance analysis results, the blade performance defects are marked, including inlet impact, outlet wake, flow channel vortex and cavitation risk; Based on the identified impeller and volute coordination issues, the impeller and volute are optimized for matching. This optimization involves matching and optimizing the inlet position, angle, and area ratio, then optimizing the clearance between the impeller and volute, and finally verifying the effectiveness of the optimized impeller and volute. The acceptable verification indicators are: pressure gradient change ≤ 0.05 MPa / m, recirculation zone area ratio ≤ 3%, and efficiency improvement ≥ 2%. Based on the identified blade performance defects, the blade shape is designed, including inlet section optimization, mid-section optimization, wrap angle optimization, outlet section optimization, trailing edge optimization, and symmetry calibration. Specifically, inlet section optimization involves adjusting the inlet angle and controlling the inlet pre-swirl; mid-section optimization involves adjusting the flow channel diffuser; outlet section optimization involves adjusting the outlet angle and thickness; and trailing edge optimization involves correcting the profiles of the pressure and suction surfaces. Finally, the matching of the impeller and volute, as well as the optimization of the blade shape, were completed.

7. The nuclear island pit pump double passage impeller hydraulic design method of claim 6, wherein, Structural reinforcement is performed based on the matched and optimized impeller, volute, and blades, including: Based on the matched and optimized impeller, volute and blades, the reinforcement areas are located, including high stress concentration areas, high wear risk areas, weak points in seismic resistance and areas sensitive to extreme working conditions. Strengthening schemes are formulated based on the identified strengthening areas. Among them, the strengthening schemes for high stress concentration areas include strengthening the blade root, impeller cover plate, and volute tongue; the strengthening schemes for volute tongue strengthening include strengthening the blade inlet leading edge, the flow channel bend, and the inner wall of the volute diffuser section; the strengthening schemes for seismic weak points include strengthening the impeller-shaft connection and the volute support structure; and the strengthening schemes for areas sensitive to extreme operating conditions include high-temperature deformation control and radiation aging resistance strengthening. Performance compatibility verification was conducted based on the established reinforcement plan, including hydraulic performance verification, structural strength verification, and wear resistance effect verification. After the performance compatibility verification was completed and passed, the impeller, volute and blades were obtained with structural reinforcement.

8. The nuclear island pit pump double passage impeller hydraulic design method of claim 7, wherein, The hydraulic performance of the reinforced structure was simulated and verified, including: Three-dimensional models of the reinforced impeller, volute, and blades were constructed using 3D modeling tools. Based on the meshing strategy of combining structured and unstructured networks, the constructed 3D model is locally refined. At the same time, through three rounds of mesh refinement, the calculated head and efficiency under different mesh sizes are compared. When the change in the calculated results is ≤1%, the final mesh size is determined. After the grid size was confirmed, a hydraulic performance analysis was performed again. This hydraulic performance analysis was conducted after the structure was reinforced. The hydraulic performance analysis results before and after structural reinforcement are compared and analyzed. The comparison analysis involves establishing a performance comparison table before and after reinforcement, including hydraulic parameters, flow field parameters and loss parameters. Then, the cause is located based on the comparison analysis results. A verification report is generated based on the analysis results and reasons.

9. The hydraulic design method for a dual-flow-channel impeller of a nuclear island sump pump according to claim 8, characterized in that, The strength of the double impeller structure was optimized based on the hydraulic performance simulation results, including: Based on the hydraulic performance simulation verification results, the key parameters in the analysis results were screened. The key parameters are pressure load data, flow velocity and centrifugal force correlation data, extreme working condition load and flow field induced vibration data. Based on the selected key parameters, a structural strength analysis model was constructed, and the finite element analysis method was used to analyze the stress, deformation, and fatigue life of the impeller under various working conditions, including static strength analysis, fatigue strength analysis, vibration modal analysis, and strength verification under extreme working conditions. Based on the analysis results of the weak points, a structural strength optimization plan is formulated, including optimization of high stress areas, adjustment of excessive deformation, strengthening of insufficient fatigue life, and elimination of resonance risk. Finally, the established structural strength optimization scheme will be verified for strength compatibility, including hydraulic performance verification, strength performance verification, and extreme working condition verification.

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