| Known as the "Heart of the Nuclear Island",the nuclear main pump for the CAP 1400 nuclear power unit of the third generation pressurized water reactor is the only device that cannot be domestically made in China.Nevertheless,the impeller and the vane(the core hydraulic components)are the most important flow passage components,which can directly determine the service life of the nuclear island.To meet the requirements comprising of high efficiency,high head and low pressure fluctuation strength,the impeller and vane from the nuclear mam pump have the characteristics of the overlarge channel curvature change and the complex curved and swept blade,which cannot be represented with the 2-D blade design method in the related optimization system.During the optimal design process,the constraint design method is the first step,which plays a fundamental and decisive role in the design system.Therefore,reconstructing a new efficient constraint design method based on the turbomachinery principle 1s the focus and difficulty of the multi-objective optimization design system research.The efficient constraint design method should be able to output the high performance design results with as fewer design variables as possible.According to the design and flow order,the nuclear main pump's impeller and vane design includes the four basic factors:?.the channel design;?.the impeller blade design;?.the vane blade design;?.the special structure design.In this paper,the above four aspects have been studied in depth,and the efficient constraint design method system was established with the combination of the physical modeling and mathematical deduction,which would be applied into the contrast test by setting the CAP 1400 canned reactor coolant pump's hydraulic model of the major national research and development projects as the reference.The main contents are as:(1)In the aspect of the channel constraint design,to solve the problems related to the asynchronous channel design,the discontinuity of the transition section and the deviation from the design objective,a new channel constraint design method has been simplified and proposed from the Medial Axial Transform theory.In the new method,aiming at the unclosed constrained conditions,two extra aided constrained conditions respectively solved with the PSO algorithm and the explicit formulas were applied into the channel design.The channel design method has two applications.Firstly,a quick meridian channel design program has been developed with the constraint channel design method,and as for the developed design program,it could design out the random channel structure whose specific speeds are from 30 to 500 on the basis of the 7 typical impeller channels.Additionally,an optimization strategy for the high efficiency and low axial load design of the hydraulic model has been proposed with the established channel design method,and with only 3 design variables and 15 groups of samples,the high efficiency and low axial load design for the coolant pump's hydraulic model could be achieved.(2)In the aspect of the constraint design for the blade,to solve the problems of the traditional design methods related to the too many design variables,the uncertain ranges and the experience-dependent preset values,this study settled down the key design variables separately,namely,the swirl velocity for the impeller blade,and the install angle for the vane blade.Pre-literature research and statistical analysis of the typical structures all confirmed that these two design variables both are increasing along the streamline,as a result,the dimensionless multi-source constrained design equations have been constructed,and the sail-like constraint zone used to generate the efficient design variables was proposed via a series of derivation.Based on the normalized sail-like constrained zone and the PSO algorithm,the adjoint optimization design programs for impeller blade and vane blade design were developed separately.Setting the impeller blade and vane blade from the CAP 1400 canned reactor coolant pump's hydraulic model of the major national research and development projects as the target,the developed design programs were applied into the design verification process: during the impeller blade design,three design cases comprising of the positive inclination angle,zero inclination angle and negative inclination angle denoted that the dynamic optimal design program could design out the new structures with better performances than the target;during the vane blade design,the optimal resulfs efficiency and head performance have been increased by 0.7% and 1.8% respectively when compared to the target.The reliability of the constraint design method and the feasibility of the developed optimal design program have been demonstrated.(3)In the aspect of the developed thought for the main coolant pump's hydraulic model,on the basis of the proposed normalized sail-like constrained zone,the influence effects from the impeller and the vane on the main coolant pump were explored after steady and unsteady analysis.After defining that the influence of vane on pressure fluctuation is higher than that of impeller,the design inference of "the impeller can be designed independently,and the vane needs to be designed adaptively" was proposed during the main coolant pump's hydraulic model developing process.A new hydraulic model was designed out based on the proposed design inference,and through comparative analysis of the performance,the pressure and the turbulence kinetic distribution of the CAP 1400 canned reactor coolant pump's hydraulic model of the major national research and development projects,the high performance of the newly developed hydraulic model was clarified,which demonstrated the feasibility of the design inference about the nuclear main pump's hydraulic model proposed in the study.(4)In the aspect of the special structure design,so as to adapt to the incomplete circumferential symmetry characteristics of the nuclear main pump,a symmetrical-nonuniform vane structure and the corresponding constraint design method has been constructed.This new method takes into consideration of the blade distance and the install location so as to describe the most design cases including the uniformly distributed vane blades.With the application of the multi-optimization method into the symmetrical-nonuniform vane design,the optimal structure has been obtained,and the effects of the design variables on the pump's performance were evaluated at the same time,The numerical results demonstrated that the optimized vane structure could effectively increase the nuclear main pump's performance at the 0.2-0.8 design flow,and improve the unsteady pressure fluctuation characteristics at the pump's outlet.Finally,the test rig was set up in the National Industrial Pump Quality Supervision and Test Center,and a series of combined validation tests have been carried out:the steady performance test,the unsteady pressure fluctuation test and vibration acceleration test have all proved the feasibility of the newly proposed constrained design method embedded in optinization progress of the coolant pump's hydraulic model. |
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