Research On Development And Flow-field Characteristic Of Seawater Circulation Pump In AP1000Nuclear Power Plant

The nuclear power industry in China entered a rapid expansion period for the development of clean energy all over the world in the past years, the construction of the first AP1000nuclear power plant which belong to the advanced third generation nuclear power technology in China boost the market of pump industry driven by nuclear power plant. The localization of nuclear power pump industry became a important target for domestic pump manufacturers, the large-scale seawater circulation pump is one of major localization projects for its significance in AP1000system. In order to improve the development level and accelerate localization process, the hydrodynamic model, structure design and flow-field characteristic of seawater circulation pump were specificly researched through theory analysis, model test and numerical simulation methods in this dissertation, in addition, so many important references data were presented through the researches on the flow-field evolution, recirculation and impeller hydrodanamic raidial force of the model pump. The main research works and innovative achievements are as follows:1. Based on the excellent hydraulic model obtained before and successful design principles, the hydraulic model of AP1000seawater circulation pump was designed with streamline method, the performance test in high accuracy closed loop presents that the hydraulic model can meet the design requirements of AP1000seawater circulation pump unit.2. The model pump flow field was calculated with standard k-ε, RNG k-ε. and SST k-ω turbulence model respectively, the results of different trubulence models were analyzed in performance characterstics and flow field distribution, and the applicabilities of trubulence models in partial load were analyzed especially, it concluded that the RNG k-ε and SST k-ω turbulence model are more applicable than standard k-ε turbulence model in partial load condition numerical simulation research.3. The secondary flow and evolution of flow field of mixed-flow pump impeller with spherical figure were researched with theory analysis method, the laws of recirculation in impeller induced by secondary flow were summed up based on theory analysis before. The general steady performance curve characteristic of mixed flow pump was analyzed, the influence from recirculation of impeller to theoretical head was researched by theory analysis, and brought out a new consept of critical flow rate which was more applicable to engineering application. The recirculation and evolution of flow field of model pump were researched with numerical simulation method, the circulation around the impeller inlet, outlet and the diffuser outlet were specifically analyzed in different flow rates, a reverse flow phenomena was found for the first time in the recirlution of impeller outlet, these results provided valuable conference data for further investigation of mixed flow pump.4. The hydrodynamic radial force and pressure pulsation around impeller outlet of model pump were calculated with unsteady numerical simulation method, and a vibration test analysis of model pump assemble was finished. The hydrodynamic radial forces of impeller in different flow rates were analyzed in time and frequency domains specifically for the first time, the characteristics of hydrodynamic radial forces at certain frequency were founded, through a further research on pressure pulsation between impeller and diffuser, it proved the influence of recirculation in impeller outlet to hydrodynamic radial force, pressure pulsation and rotor-stator interaction.5. The inlet sump project with wedge shape distributor was designed based on former method, the reasonable dimensions of inlet sump obtained through a analysis based on objective function optimization method. The unsteady numerical simulation of inlet sump and model pump was carried out, and the hydrodynamic radial force characteristic under inlet sump was researched, the result presents that there were peak values around zero and vane-pass frequency which are caused by inlet sump apparently, and the force values increased with decreasing flow rate.6. Based on the structure design of seawater circulation pump unit, the support structure dynamic stiffness, rotor critical speed and operability of pump unit were researched with theory and finite element analysis method. The results present that the dynamic stiffness of support structure decreased with increasing external excitation frequency when lower then1st resonance frequency, the value of stiffness is in direct proportion to the thickness of pump case. The1st lateral resonance frequency of rotor component considering dynamic stiffness is about17.5Hz, and it’s safe for pump operation. The structure of pump assemble satisfied the operability requirement under the design seismic response spectrum input.