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

Abstract

The invention discloses a hydraulic design method for a double-flow-channel impeller of a nuclear island pit pump, relates to the technical field of hydraulic design of impellers, and aims to solve the problem that the accuracy of double-flow-channel design is reduced. Through whole-process working condition parameter confirmation and performance index definition innovation, comprehensiveness and traceability of data are achieved, multi-dimensional parameters are called from a database, identification is established, source data reliability is ensured, flow is equally divided through symmetrical flow channels, resistance is reduced through streamline baffle tongues, a flow field is simulated and optimized in combination with fluid dynamics, eddy current and hydraulic losses are reduced, and the method is suitable for large-scale production. Through finite element analysis and compatibility verification, the hydraulic performance is guaranteed while the structural strength is improved, and through extreme working condition verification, it is ensured that equipment resists the influences of irradiation, high temperature and the like.

Description

Technical Field

[0001] This invention relates to the field of impeller hydraulic design technology, specifically a method for designing a dual-flow-channel impeller for a nuclear island sump pump. Background Technology

[0002] As a critical safety device in nuclear power plants, the nuclear island sump pump must transport media containing impurities, at high temperatures, and potentially radioactive under extreme operating conditions, placing stringent requirements on impeller hydraulic performance and structural reliability. Current designs suffer from incomplete acquisition of operating parameters and a lack of traceability mechanisms, leading to insufficient reliability of basic data; vague performance indicator extraction, with no clear nuclear safety priority in case of conflicts, easily deviating from core safety requirements; poor material selection and adaptability to operating conditions, lack of nuclear-grade verification, and insufficient wear resistance and radiation resistance; poor flow channel design symmetry, poor impeller-volute matching, resulting in high hydraulic losses, low efficiency, and difficulty in balancing structural strength and hydraulic performance, making it prone to failure due to high stress and wear, and failing to meet the long-term safe operation requirements of the nuclear island. Summary of the Invention

[0003] The purpose of this invention is to provide a hydraulic design method for a dual-flow-channel impeller of a nuclear island sump pump. Through the confirmation of full-process operating parameters and the innovative definition of performance indicators, it achieves comprehensive and traceable data. It retrieves multi-dimensional parameters from the database and establishes identifiers to ensure the reliability of source data. Symmetrical flow channels distribute the flow evenly, and streamlined tongues reduce resistance. Combined with fluid dynamics simulation, the flow field is optimized to reduce eddies and hydraulic losses. Through finite element analysis and compatibility verification, it improves structural strength while ensuring hydraulic performance. Extreme operating condition verification ensures that the equipment can withstand the effects of radiation, high temperature, etc., which can solve the problems in the prior art.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] The hydraulic design method for a dual-flow-channel impeller of a nuclear island sump pump includes:

[0006] First, confirm the parameter data of the original operating conditions; define performance indicators based on the confirmed operating condition parameter data; design and select materials based on the operating condition parameter data and performance indicators; construct the basic flow channel structure of the dual-flow channel impeller based on the performance indicators, and construct a three-dimensional flow channel model based on the basic flow channel structure; analyze the hydraulic performance of the initial impeller under the set operating conditions using the three-dimensional flow channel model; match the impeller and volute based on the hydraulic performance analysis results, and then optimize the shape of the blades; strengthen the structure based on the matched and optimized impeller, volute, and blades; perform hydraulic performance simulation verification on the strengthened structure; optimize the structural strength of the dual-impeller based on the hydraulic performance simulation verification results.

[0007] Preferably, the parameter data of the original operating conditions are confirmed, including:

[0008] Retrieve the original operating condition parameter data from the database, including media characteristic parameters, operating performance parameters, environmental parameters, and safety parameters;

[0009] 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.

[0010] After the data is retrieved, a parameter data identifier is created, which includes the data acquisition time, instrument model, and operator.

[0011] The final operating condition parameter data is obtained after the parameter data is identified.

[0012] Preferably, performance indicators are defined based on confirmed operating condition parameter data, including:

[0013] Based on performance indicators, key data are extracted from the operating condition parameter data;

[0014] Among them, the performance indicators include hydraulic performance, structural adaptation, safety redundancy, and lifespan.

[0015] 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.

[0016] When there are conflicts in key data across different performance metrics, conflict coordination should be carried out based on nuclear safety priorities.

[0017] 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.

[0018] Performance index data obtained after conflict coordination, including operating condition parameter data.

[0019] Preferably, the material is selected based on operating condition parameter data and performance indicators, including:

[0020] 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.

[0021] Based on the constraints, select the corresponding material categories from the nuclear power standard material library, including metallic and non-metallic materials;

[0022] For the selected material category, the operating condition parameter requirements are verified, including corrosion resistance assessment, wear resistance assessment, and mechanical property assessment.

[0023] 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.

[0024] The optimized materials will undergo nuclear safety verification again, which includes material traceability, material certification, and irradiation aging simulation.

[0025] After nuclear safety verification is completed and passed, the materials selected for the design are obtained.

[0026] Preferably, a basic flow channel structure for the dual-flow channel impeller is constructed based on performance indicators, and a three-dimensional flow channel model is constructed based on the basic flow channel structure, including:

[0027] The performance indicators are converted into constraints on the flow channel geometry parameters, including flow-head constraints, efficiency constraints, and wear resistance constraints.

[0028] 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.

[0029] 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.

[0030] 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%.

[0031] After the 3D model is constructed, the flow channel 3D model is obtained.

[0032] Preferably, the hydraulic performance of the initial impeller under set operating conditions is analyzed using a three-dimensional flow channel model, including:

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Finally, the analysis results of the core hydraulic performance indicators are used to generate an analysis report.

[0040] Preferably, the impeller and volute are matched based on the hydraulic performance analysis results, and then the blade shape is optimized, including:

[0041] 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.

[0042] 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;

[0043] Based on the identified impeller and volute coordination issues, the impeller and volute are optimized for matching. The matching optimization involves matching and optimizing the inlet position, angle, and area ratio, optimizing the gap between the impeller and volute, and finally verifying the effect of the optimized impeller and volute. The qualified verification indicators are: pressure change gradient ≤ 0.05 MPa / m, recirculation zone area ratio ≤ 3%, and efficiency improvement ≥ 2%.

[0044] 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.

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

[0046] Preferably, structural reinforcement is performed based on the matched and optimized impeller, volute, and blades, including:

[0047] 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.

[0048] 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.

[0049] Performance compatibility verification was conducted based on the established reinforcement plan, including hydraulic performance verification, structural strength verification, and wear resistance effect verification.

[0050] After the performance compatibility verification was completed and passed, the impeller, volute and blades were obtained with structural reinforcement.

[0051] Preferably, the hydraulic performance of the reinforced structure is verified by simulation, including:

[0052] Three-dimensional models of the reinforced impeller, volute, and blades were constructed using 3D modeling tools.

[0053] 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.

[0054] After the grid size was confirmed, a hydraulic performance analysis was performed again. This hydraulic performance analysis was conducted after the structure was reinforced.

[0055] 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.

[0056] A verification report is generated based on the analysis results and reasons.

[0057] Preferably, the strength of the double impeller structure is optimized based on the hydraulic performance simulation verification results, including:

[0058] 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.

[0059] 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.

[0060] 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.

[0061] Finally, the established structural strength optimization scheme will be subjected to strength compatibility verification, including hydraulic performance review, strength performance verification, and extreme working condition verification.

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

[0063] 1. The dual-flow-channel impeller hydraulic design method for nuclear island sump pumps provided by this invention achieves comprehensiveness and traceability of data through the confirmation of full-process operating parameters and the innovative definition of performance indicators. It retrieves multi-dimensional parameters from the database and establishes identifiers to ensure the reliability of source data; it handles indicator conflicts according to nuclear safety priorities, clarifies design objectives, provides accurate basis for material selection, flow channel design, etc., reduces design errors caused by parameter deviations, improves the scientificity and pertinence of nuclear island sump pump design, and ensures that equipment performance meets standards from the source.

[0064] 2. The dual-flow-channel impeller hydraulic design method for nuclear island sump pumps provided by this invention significantly improves operating efficiency and stability through innovative dual-flow-channel impeller design and hydraulic performance optimization. Symmetrical flow channels distribute flow evenly, streamlined tongues reduce resistance, and fluid dynamics simulation optimizes the flow field, reducing eddies and hydraulic losses. Three-dimensional modeling and mesh generation ensure accurate analysis and effectively reduce cavitation risk. Impeller and volute matching and blade optimization further improve efficiency, enabling the equipment to operate efficiently and stably under complex nuclear island conditions.

[0065] 3. The dual-flow-channel impeller hydraulic design method for nuclear island sump pumps provided by this invention achieves a synergistic innovation of structural reinforcement and strength optimization, balancing safety and durability. It accurately locates weak points such as high-stress areas and formulates targeted reinforcement schemes. Through finite element analysis and compatibility verification, it ensures hydraulic performance while improving structural strength. Extreme working condition verification ensures that the equipment can withstand the effects of radiation and high temperature, extending its service life and meeting the high safety and long-cycle operation requirements of the nuclear island, thus achieving a balance between strength and performance. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of the hydraulic design process of the dual-flow-channel impeller for the nuclear island sump pump of the present invention. Detailed Implementation

[0067] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0068] To address the issues in existing technologies, such as incomplete retrieval of operating parameters, lack of identification and traceability; inaccurate performance index extraction, lack of nuclear safety priority in conflict resolution; and mismatch between material selection and operating performance, and lack of nuclear safety verification, please refer to [the relevant documentation / reference]. Figure 1 This embodiment provides the following technical solution:

[0069] The hydraulic design method for a dual-flow-channel impeller of a nuclear island sump pump includes:

[0070] First, confirm the parameter data of the original operating conditions; define performance indicators based on the confirmed operating condition parameter data; design and select materials based on the operating condition parameter data and performance indicators; construct the basic flow channel structure of the dual-flow channel impeller based on the performance indicators, and construct a three-dimensional flow channel model based on the basic flow channel structure; analyze the hydraulic performance of the initial impeller under the set operating conditions using the three-dimensional flow channel model; match the impeller and volute based on the hydraulic performance analysis results, and then optimize the shape of the blades; strengthen the structure based on the matched and optimized impeller, volute, and blades; perform hydraulic performance simulation verification on the strengthened structure; optimize the structural strength of the dual-impeller based on the hydraulic performance simulation verification results.

[0071] Specifically, confirming the original operating condition parameters is the foundation of the entire design. This step ensures the accuracy of the initial design data, providing a reliable basis for subsequent stages, avoiding design errors caused by parameter deviations from the outset, reducing the probability of rework, and improving design efficiency. Defining performance indicators based on the confirmed operating condition parameters clarifies the design objectives, provides clear guidance for impeller design, and accurately addresses the actual operating needs of the nuclear island sump pump, ensuring the final product meets performance standards and enhancing the design's relevance and effectiveness. Material selection based on operating condition parameters and performance indicators ensures that the chosen materials are suitable for the complex and harsh working environment of the nuclear island, possessing sufficient strength, corrosion resistance, and stability, extending impeller lifespan, reducing equipment failure risks, and guaranteeing long-term reliable pump operation. Constructing a dual-flow channel basic flow channel structure and establishing a 3D model effectively improves the pump's cavitation resistance and operational stability. The 3D model provides an intuitive and accurate platform for subsequent analysis, facilitating detailed research on the internal flow conditions of the flow channels, aiding in the optimization of the flow channel design, and utilizing the 3D model to analyze the initial... Impeller hydraulic performance analysis allows for early-stage design flaw detection and timely adjustments, preventing losses caused by defects discovered after manufacturing and reducing design costs. It also provides data support for subsequent optimization, enhancing the scientific rigor of the design. Optimizing impeller-volute matching and blade shape based on analysis results improves fluid flow within the pump, reduces hydraulic losses, increases pump efficiency, and enhances operational stability, enabling the pump to perform optimally under set operating conditions. Strengthening the optimized structure improves the overall strength and rigidity of the impeller, allowing it to withstand various loads and impacts under nuclear island conditions, improving equipment safety and meeting the high reliability requirements of the nuclear island. Hydraulic performance simulation verification after strengthening comprehensively verifies the optimization effect, ensuring stable and compliant impeller performance under various operating conditions, further validating the design's rationality, and reducing risks in actual operation. Optimizing the impeller structural strength based on simulation verification results achieves a balance between hydraulic performance and structural strength, ensuring efficient operation while making the impeller structure more rational, extending its service life, and improving the overall performance and reliability of the nuclear island sump pump.

[0072] Confirm the parameter data of the original operating conditions, including:

[0073] Retrieve the original operating condition parameter data from the database, including media characteristic parameters, operating performance parameters, environmental parameters, and safety parameters;

[0074] 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.

[0075] After the data is retrieved, a parameter data identifier is created, which includes the data acquisition time, instrument model, and operator.

[0076] The final operating condition parameter data is obtained after the parameter data is identified.

[0077] Specifically, multi-dimensional parameters are retrieved from the database, covering media characteristics, operational performance, environmental, and safety parameters, achieving comprehensive data acquisition. The detailed parameters of media characteristics accurately reflect the essential properties of the transported media; operational performance parameters directly address core operational indicators; environmental parameters align with the actual pit scenario; and safety parameters ensure reliability under extreme conditions. The synergy of these multiple parameters provides panoramic data support for the design, avoiding design deviations caused by missing information. Media characteristics are categorized by physical, chemical, and special properties; operational performance clearly defines core indicators and parameters such as power and pressure; environmental parameters are refined to the level of pit geometry and suction conditions; and safety parameters focus on operating time and extreme conditions. This structured classification enables designers to quickly locate key data, improves parameter retrieval efficiency, and ensures accurate matching between the design process and actual operating conditions. Records of acquisition time, instrument model, and operator information construct a complete data traceability chain, facilitating subsequent verification of data validity. When design or operational problems arise, the data acquisition process can be traced back through identification information to identify the source of errors, providing a basis for data correction and responsibility determination, and improving the standardization of data management. Finally, after the operating parameters are confirmed through identification, the reliability of the data is significantly improved. Through multi-stage verification, invalid or erroneous data is eliminated, ensuring that the parameters input into the design stage are true and valid. This reduces design risks caused by data distortion from the source, laying a solid foundation for subsequent material selection, flow channel design, and other stages, and ensuring the scientific nature and accuracy of the entire hydraulic design process. Through systematic data acquisition, classification, and verification, a closed-loop parameter confirmation mechanism is formed, meeting the stringent data accuracy requirements of nuclear island equipment and providing a reliable guarantee for the efficient advancement of the entire design process.

[0078] Performance indicators are defined based on the confirmed operating condition parameter data, including:

[0079] Based on performance indicators, key data are extracted from the operating condition parameter data;

[0080] Among them, the performance indicators include hydraulic performance, structural adaptation, safety redundancy, and lifespan.

[0081] 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.

[0082] When there are conflicts in key data across different performance metrics, conflict coordination should be carried out based on nuclear safety priorities.

[0083] 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.

[0084] Performance index data obtained after conflict coordination, including operating condition parameter data.

[0085] Specifically, key data is extracted from multiple dimensions, covering hydraulic performance, structural adaptation, safety redundancy, and lifespan, making the performance indicator system comprehensive and systematic. This avoids omitting key elements of nuclear island sump pump operation, ensuring that the indicators fully reflect equipment operation requirements and provide complete guidance for subsequent design. Key data is precisely extracted for different parameter types, such as focusing on wear and corrosion resistance indicators for media characteristics, and locking in core indicators such as flow-head curves for operational performance. This closely links performance indicators with actual operating conditions, improving the accuracy and practicality of the indicators, ensuring that the design closely follows the core needs of equipment operation, and establishing a conflict coordination mechanism for nuclear safety priorities, listing key safety parameter data as the first priority, highlighting the principle of nuclear safety first. When data conflicts occur, safety indicators are prioritized to ensure the design does not deviate from the high safety standards of nuclear facilities, fundamentally safeguarding the bottom line of equipment operation safety. Data contradictions are resolved through clear prioritization, avoiding subjective arbitrariness and making performance indicator data more scientific and reasonable. This ensures that the final indicators not only meet multi-dimensional requirements but also make optimal trade-offs in case of conflicts, enhancing the reliability of the indicators. The entire process, from data extraction to conflict handling, forms a closed loop, ensuring that the final performance indicator data is both comprehensive and focused, covering all aspects of equipment operation requirements while highlighting safety and core performance. This provides high-quality indicator basis for subsequent material selection, structural design, and other stages, improving the scientific rigor and effectiveness of the overall design. The correspondence between operating condition parameters and performance indicators in the performance indicator definition is shown in the following table:

[0086]

[0087]

[0088] Material selection is based on operating condition parameters and performance indicators, including:

[0089] 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.

[0090] Based on the constraints, select the corresponding material categories from the nuclear power standard material library, including metallic and non-metallic materials;

[0091] For the selected material category, the operating condition parameter requirements are verified, including corrosion resistance assessment, wear resistance assessment, and mechanical property assessment.

[0092] 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.

[0093] The optimized materials will undergo nuclear safety verification again, which includes material traceability, material certification, and irradiation aging simulation.

[0094] After nuclear safety verification is completed and passed, the materials selected for the design are obtained.

[0095] Specifically, by cross-mapping operating condition parameters and performance indicators to clarify constraints, material selection is based on precise criteria. The combined effect of medium characteristic constraints and performance indicator constraints ensures a high degree of matching between material properties and the operational requirements of the nuclear island sump pumps, avoiding equipment failures due to incompatible material properties. This enhances the targeted nature of material selection. Nuclear power standard materials undergo rigorous certification to meet the basic safety requirements of nuclear facilities, reducing potential risks from non-standard materials and laying a solid safety foundation for subsequent use. The operating condition parameter verification process comprehensively evaluates the corrosion resistance, wear resistance, and mechanical properties of materials, identifying potential shortcomings in material compatibility under actual operating conditions. Targeted verification eliminates unqualified materials, ensuring stable performance of selected materials during long-term operation and extending equipment lifespan. Optimization methods involving multi-material composites and heat treatment strengthening integrate the advantages of different materials. For example, composite materials can balance corrosion resistance and wear resistance, while heat treatment strengthening improves mechanical strength, making material performance more comprehensive and adaptable to the complex operating conditions of the nuclear island. The nuclear safety verification process, through material traceability, certification, and irradiation aging simulation, comprehensively ensures the nuclear safety compatibility of materials. In particular, irradiation aging simulation can predict the performance changes of materials under long-term irradiation environment, ensure their stability under extreme operating conditions, and meet the high safety standards of nuclear islands. The entire process forms a closed loop of "constraint-selection-verification-optimization-re-verification", which controls the material performance and nuclear safety requirements at each level, ensuring that the materials meet the operational requirements and comply with nuclear safety regulations, and significantly improving the scientific nature and reliability of material selection.

[0096] To address the problems in existing technologies, such as mismatch between flow channel geometry parameters and performance indicators, poor symmetry; unreliable evaluations due to poor mesh quality and inaccurate parameter calculations in hydraulic performance analysis; poor impeller-volute matching leading to flow imbalance; and blade inlet impact defects, resulting in low efficiency, high energy consumption, and high cavitation risk, please refer to [the relevant documentation / reference]. Figure 1 This embodiment provides the following technical solution:

[0097] 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:

[0098] The performance indicators are converted into constraints on the flow channel geometry parameters, including flow-head constraints, efficiency constraints, and wear resistance constraints.

[0099] 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.

[0100] 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.

[0101] 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%.

[0102] After the 3D model is constructed, the flow channel 3D model is obtained.

[0103] Specifically, performance indicators are transformed into geometric parameter constraints, allowing the flow channel design to directly address core requirements such as flow rate-head and efficiency. This ensures a close correlation between geometric parameters and performance targets, preventing a disconnect between design and actual needs, and improving the design's relevance and accuracy. The initial geometric framework design is scientific, with symmetrical dual flow channels each handling 50% of the flow, balancing the load and reducing vibrations caused by hydraulic imbalances. Streamlined tongues reduce fluid resistance, and helical blade ribs optimize fluid guidance. The 4-6 blade count balances efficiency and anti-clogging, enhancing structural stability and operational efficiency. The fluid dynamics analysis and optimization process uses two-dimensional cross-sections to simulate velocity and pressure distribution, precisely adjusting the blade inlet angle and flow channel parameters, effectively improving flow within the channel. The design minimizes eddy currents and hydraulic losses, improves impeller hydraulic efficiency, and proactively avoids potential flow defects, reducing testing costs. The rigorous 3D model construction process ensures precise blade surface generation and component assembly. Symmetrical flow channels are replicated and rotated 180° to maintain structural symmetry. Consistency verification with an area deviation of ≤±2% ensures balanced performance of the dual flow channels, avoiding performance fluctuations caused by flow channel asymmetry. This provides a high-precision digital model for subsequent manufacturing, reducing processing errors. The overall solution forms a closed loop of "performance constraints - geometric design - fluid optimization - 3D verification," balancing hydraulic performance and structural reliability. It meets the stringent requirements of nuclear island sump pumps for high efficiency, stability, and wear resistance, significantly enhancing the scientific rigor and engineering practicality of the impeller design.

[0104] The hydraulic performance of the initial impeller under set operating conditions was analyzed using a three-dimensional flow channel model, including:

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] Finally, the analysis results of the core hydraulic performance indicators are used to generate an analysis report.

[0112] Specifically, the fluid calculation scope is comprehensive, covering the impeller inlet section, rotation domain, and the transition section from the outlet to the volute inlet, completely covering the key areas of fluid flow through the impeller. It can comprehensively capture fluid flow characteristics, avoiding analytical omissions caused by limitations in the calculation scope, and providing complete data support for hydraulic performance evaluation. The scientific mesh generation combines structured and unstructured meshes, and sets boundary layer meshes on the blade surface and flow channel wall, ensuring both computational efficiency and improving the calculation accuracy in key areas. It can accurately simulate the fluid flow state near the wall, reducing the impact of mesh generation on the analysis results. The boundary condition definitions are realistic; by inputting the basic parameters of the set operating conditions, the boundary conditions of the inlet, outlet, wall, and rotation domain are clearly defined, ensuring that the hydraulic performance analysis is based on real operating scenarios and that the analysis results highly match the actual operating conditions, improving the overall performance. The results provide valuable reference, and the turbulence model is appropriately selected. The SSTk-ω model balances the simulation accuracy for near-wall flow and the mainstream region, making it suitable for complex turbulent flow analysis within the impeller. With targeted solver parameter settings, it can accurately calculate core parameters such as head and efficiency, ensuring the reliability of hydraulic performance evaluation. The analysis content is systematic and comprehensive, including both basic performance parameter calculations and cavitation performance evaluation, as well as detailed flow field analysis such as velocity and pressure fields. It can comprehensively evaluate impeller performance from macroscopic performance to microscopic flow state, providing a clear direction for subsequent optimization and effectively improving the completeness of the initial impeller design. Through precise modeling, scientific calculation, and comprehensive analysis, a complete hydraulic performance evaluation system is formed, providing a detailed and reliable analysis report for impeller optimization, significantly improving the pertinence and efficiency of design optimization.

[0113] Based on the hydraulic performance analysis results, the impeller and volute are matched, and then the blade shape is optimized, including:

[0114] 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.

[0115] 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;

[0116] Based on the identified impeller and volute coordination issues, the impeller and volute are optimized for matching. The matching optimization involves matching and optimizing the inlet position, angle, and area ratio, optimizing the gap between the impeller and volute, and finally verifying the effect of the optimized impeller and volute. The qualified verification indicators are: pressure change gradient ≤ 0.05 MPa / m, recirculation zone area ratio ≤ 3%, and efficiency improvement ≥ 2%.

[0117] 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.

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

[0119] Specifically, by focusing on specific issues such as flow distribution imbalance and inlet impact, and avoiding blind adjustments, optimization measures directly address performance shortcomings, improving rectification efficiency, reducing ineffective design costs, and perfecting the impeller and volute matching optimization system. This system progresses step-by-step from inlet parameters to clearance adjustments, and quantitative verification indicators are set. Hard indicators such as pressure change gradient and recirculation zone ratio ensure that the optimization effect is measurable and controllable. The requirement of an efficiency improvement of ≥2% directly points to performance improvement, making the matching effect both stable and economical. Blade shape design covers the entire process optimization: inlet section adjustment reduces impact loss, mid-section diffusion optimization improves flow uniformity, and outlet section and trailing edge correction reduces wake effect. Multi-dimensional optimization synergistically improves blade hydraulic performance, while symmetry calibration ensures the consistency of dual-channel performance, adapting to the high stability requirements of nuclear island equipment. Quantitative indicators are used to verify optimization results, avoiding "pseudo-optimization," ensuring that the adjusted impeller and volute have small pressure fluctuations, less recirculation, and high efficiency in actual operation. The blades also exhibit enhanced cavitation resistance and wear resistance, extending equipment life.

[0120] To address the problems of low hydraulic efficiency, high cavitation risk, poor impeller-volute matching, susceptibility to structural failure due to high stress, wear, and corrosion, and insufficient adaptability to seismic and extreme operating conditions in existing technologies, please refer to [the relevant documentation / reference]. Figure 1 This embodiment provides the following technical solution:

[0121] Structural reinforcement is performed based on the matched and optimized impeller, volute, and blades, including:

[0122] 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.

[0123] 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.

[0124] Performance compatibility verification was conducted based on the established reinforcement plan, including hydraulic performance verification, structural strength verification, and wear resistance effect verification.

[0125] After the performance compatibility verification was completed and passed, the impeller, volute and blades were obtained with structural reinforcement.

[0126] Specifically, the reinforcement is precisely positioned, focusing on key areas such as high stress concentration areas and high wear risk areas, avoiding the waste of resources caused by indiscriminate reinforcement, so that the reinforcement measures directly target the weak points of the structure, improve the reinforcement efficiency, and ensure that each reinforcement work can address potential failure risks in a targeted manner. The reinforcement plan is targeted, and differentiated measures are taken according to the characteristics of different areas. For example, strengthening the blade root and cover plate in high stress concentration areas, strengthening the connection and support structure in seismic weak points, and focusing on high temperature and radiation protection in extreme working condition sensitive areas can maximize the structure's resistance to specific risks and enhance overall stability. The performance compatibility verification process is comprehensive. Hydraulic performance verification ensures that the reinforcement does not affect the optimized hydrodynamic characteristics, structural strength verification ensures that the reinforcement effect meets the standards, and wear resistance verification confirms the reinforcement's role in extending life. Multi-dimensional verification avoids performance imbalance caused by reinforcement and achieves synergistic improvement of structural strength and hydraulic performance. High temperature deformation control and radiation aging resistance reinforcement in extreme working condition sensitive areas are specifically designed for the special environment of the nuclear island and can effectively resist the effects of long-term radiation and temperature fluctuations, meeting the stringent requirements of nuclear safety for long-term reliable operation of equipment. The overall solution forms a closed loop of "precise positioning - targeted reinforcement - comprehensive verification", which not only consolidates the performance results of the previous matching and optimization, but also improves the safety redundancy and life of the equipment through structural reinforcement. It combines scientific and engineering practicality and provides a solid guarantee for the stable operation of the nuclear island sump pump.

[0127] The hydraulic performance of the reinforced structure was simulated and verified, including:

[0128] Three-dimensional models of the reinforced impeller, volute, and blades were constructed using 3D modeling tools.

[0129] 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.

[0130] After the grid size was confirmed, a hydraulic performance analysis was performed again. This hydraulic performance analysis was conducted after the structure was reinforced.

[0131] 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.

[0132] A verification report is generated based on the analysis results and reasons.

[0133] Specifically, the 3D model accurately recreates the structural features after reinforcement, providing a high-fidelity geometric carrier for simulation. By precisely mapping the size and shape of the reinforced parts, the detailed features of key structures such as blades and volutes are fully preserved, avoiding verification deviations caused by model distortion. This lays a reliable foundation for subsequent flow field analysis, ensuring the authenticity of the verification results from the source. Structured and unstructured meshes are appropriately matched with complex flow channel morphologies, and local refinement of the blade surface and flow channel wall can accurately capture near-wall flow details. Three rounds of mesh refinement verification are performed until the change in calculation results is ≤1%. The influence of mesh size on the results is eliminated through mesh independence testing, ensuring stable and reliable calculation of core parameters such as head and efficiency, reducing numerical error interference. By establishing a comparison table covering hydraulic parameters (head, efficiency), flow field parameters (velocity distribution, pressure gradient), and loss parameters (hydraulic loss, local eddy current loss), the impact of reinforcement measures on performance can be quantitatively evaluated. For example, if the loss in the recirculation zone is reduced by 30% after reinforcement, it can be directly linked to the effect of flow channel optimization, achieving precise tracing of "measures-phenomena-results" and providing data support for structural improvement. The comparative analysis not only focuses on changes in performance indicators but also traces the root cause through differences in flow field parameters. For instance, increased pressure fluctuations may originate from abrupt changes in the flow channel at the reinforced area, thus guiding subsequent structural fine-tuning. This logical closed loop of "results leading to causes" avoids performance imbalances caused by blind reinforcement, ensuring that structural reinforcement improves strength without compromising hydraulic efficiency. From model building to mesh verification, and then to performance comparison and cause analysis, each step is supported by traceable quantitative data, meeting the stringent safety and reliability requirements of nuclear island equipment. The report not only verifies the effectiveness of the reinforcement measures but also provides a clear direction for subsequent iterative optimization, achieving continuous improvement through "reinforcement-verification-improvement," and balancing the synergistic optimization of structural strength and hydraulic performance.

[0134] The strength of the double impeller structure was optimized based on the hydraulic performance simulation results, including:

[0135] 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.

[0136] 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.

[0137] 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.

[0138] Finally, the established structural strength optimization scheme will be subjected to strength compatibility verification, including hydraulic performance review, strength performance verification, and extreme working condition verification.

[0139] Specifically, by extracting key parameters such as the correlation data between pressure load, flow velocity, and centrifugal force, redundant information is eliminated, allowing structural strength analysis to directly connect with hydraulic performance verification results and avoiding interference from irrelevant data. This precise screening reduces computational load while ensuring that each analysis closely adheres to the fundamental stress on the impeller, laying a reliable data foundation for subsequent strength optimization. This meets the stringent requirements for analytical accuracy in nuclear island equipment. A finite element analysis method is used to construct the model, simultaneously conducting static strength, fatigue strength, vibration mode, and extreme condition verifications, achieving full-scenario coverage from normal operation to extreme conditions. For example, vibration mode analysis can identify resonance risks in advance, while extreme condition verification simulates the structural response under accident conditions, comprehensively capturing strength weaknesses and avoiding risk omissions caused by single-condition analysis. Measures are formulated for specific issues such as optimization of high-stress areas and adjustment of deformation exceeding limits. For instance, rounded transition optimization is used for high-stress areas at the blade root, and support structures are added to areas with excessive deformation, ensuring that each optimization action directly addresses strength weaknesses. This precise matching of "problem-solution" avoids the waste of resources caused by blindly strengthening, significantly improves the balance of structural strength, ensures that strength optimization does not damage the flow channel morphology and hydraulic efficiency through hydraulic performance verification, confirms the effectiveness of optimization measures through strength performance verification, and simulates structural stability under extreme conditions. This multi-dimensional verification avoids the optimization trap of "paying for one thing at the expense of another," achieving synergistic improvement of structural strength and hydraulic performance, meeting the dual requirements of high efficiency and safety for nuclear island sump pumps. It uses the results of hydraulic performance verification to deduce structural strength requirements, and then uses strength optimization to provide feedback on hydraulic performance compatibility, forming a closed-loop logic of "hydraulic-strength" two-way verification. This design approach ensures the structural stability of the impeller under complex flow fields while maintaining its high-efficiency hydraulic characteristics, providing key technical support for the long-term reliable operation of nuclear island equipment.

[0140] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0141] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A hydraulic design method for a dual-flow-channel impeller of 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 results.

2. The hydraulic design method for the dual-flow-channel impeller of the nuclear island sump pump 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 hydraulic design method for the dual-flow-channel impeller of the nuclear island sump pump 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 hydraulic design method for the dual-flow-channel impeller of the nuclear island sump pump 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 hydraulic design method for the dual-flow-channel impeller of the nuclear island sump pump according to claim 4, characterized in that, 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.

6. The hydraulic design method for a dual-flow-channel impeller of a nuclear island sump pump according to claim 5, 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.

7. The hydraulic design method for a dual-flow-channel impeller of a nuclear island sump pump according to claim 6, 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. The matching optimization involves matching and optimizing the inlet position, angle, and area ratio, optimizing the gap between the impeller and volute, and finally verifying the effect of the optimized impeller and volute. The qualified verification indicators are: pressure change gradient ≤ 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.

8. The hydraulic design method for a dual-flow-channel impeller of a nuclear island sump pump according to claim 7, characterized in that, 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.

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 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.

10. The hydraulic design method for a dual-flow-channel impeller of a nuclear island sump pump according to claim 9, 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 subjected to strength compatibility verification, including hydraulic performance review, strength performance verification, and extreme working condition verification.

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