Correlation Research Between The Load Distribution Of Blade And Performance In Nuclear Main Pump

The nuclear main pump is the only high-speed rotating equipment inside the nuclear island.It's reliability and operating stability are of great significance for cooling the reactor core and preventing the occurrence of nuclear power plant accidents.However,the load of the blade of the main pump often affects its fatigue life and efficiency.Therefore,this paper focuses on the study of the load of blade of the main pump.The object of this paper is the model pump of nuclear main pump which is designed independently.Through numerical simulation and relevant experimental data,the internal flow characteristics and blade load distribution of the model pump under steady-state conditions and unsteady design conditions are studied in-depth.The influence of the number of different impeller blades on the performance of the model pump,the internal flow field and the distribution law of the blade load are studied too.The main research contents and results obtained are as follows:1.Internal flow characteristics and blade load distribution of nuclear main pump under different steady operation conditions.The three dimensional constant numerical calculation for the model pump of the nuclear main pump under different flow conditions is carried out.The results indicated that the working ability of the blade increases gradually from suction surface to pressure surface of blade.In order to obtain better hydraulic performance of impeller,the change trend of blade load needs to be flat and the peak point of blade load should be close to the impeller exit.According to the impeller performance under different working conditions,the blade load has the optimum change rule.The dynamic pressure load on the intermediate flow line of impeller blade is decreasing as the flow rate increases.And the reduction of the dynamic load is more obvious than the static load.The lower the proportion of the dynamic blade load in the total blade load,the higher the impeller efficiency.2.The internal flow characteristics and blade load distribution law of the nuclear main pump under unsteady design conditions.Through the unsteady numerical simulation,the internal flow characteristics and the blade load distribution law in the unsteady state of the design condition are analyzed.Under unsteady conditions,the instantaneous lift and instantaneous efficiency of the pump change in a group of two phases,a high-to-low trend occurs,and the same phenomenon occurs in each cycle,showing a cyclically changing state.At the same time,the flow line at the impeller changes according to a certain periodicity,and the flow line at the guide vane also shows periodical variation with the periodic rotation of the impeller.In addition,as the phase changes from ?=77° to ?=360°,the dynamic pressure loading,static pressure loading and total load change on the blade flow line in different phases are basically the same,and the blade load of the nuclear main pump decreases first.It will rise and show the same phenomenon in every cycle,that is,the blade load under unsteady conditions will show a periodically changing state.3.The correlation analysis of the number of impeller blades of a nuclear main pump and the load of the blade.The three dimensional constant numerical calculation of the core pump model with different impeller blades is carried out.The results show that: remaining the number of blade leaves unchanged,with the increasing of blade number,pump lift will increase,pump efficiency increases first and then decreases.So we can see that only through the rational matching of the number of impeller blades and the number of guide vane blades,the hydraulic performance of pump could achieve the best value.The change gradient of the blade load gradually slows down with the increase of impeller blades number,and the peak point of load will become gradually near the edge of the blade outlet.What's more,the dynamic pressure load on the pump performance will have a more significant impact.When the dynamic load coefficient and the static load coefficient are distributed in a certain proportion and the peak point of the dynamic load coefficient is located in the middle of the flow line of the blade,the pump will have better performance.