Research And Promotion Of Cavitation Performance Of The Secondary Circuit Coolant Pump For Sodium-cooled Fast Reactor

At present,the secondary circuit coolant pump of sodium-cooled fast reactor is the core equipment of the fourth generation nuclear that is the most advanced power system in the world.It that suction level of the secondary circuit coolant pump of sodium-cooled fast reactor,which is different from previous nuclear power plant coolant system pumps,interconnects with the atmosphere provides condition for cavitation in the secondary circuit coolant pump of sodium-cooled fast reactor.Cavitation damages safety and stability of pump operation.Accurate prediction results of cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor under different flow rate conditions provide important reference for the safe and stable operation of the sodium pump or even the four generation nuclear power system.The analytical results of as accurate cavitation flow field as possible in the secondary circuit coolant pump of sodium-cooled fast reactor under different flow rate conditions can provide reference resources for improving its cavitation performance.The thesis is studied in the following 5 aspects:1.Determining more accurate cavitation model that predicts cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor under different flow rate conditions.Using Zwart-Gerber-Belamri and Schnerr&Sauer cavitation models,which are more accurate in predicting cavitation performance of centrifugal pumps,the secondary circuit coolant pump of sodium-cooled fast reactor is unsteady numerical simulated.The results show that,head calculated values are greater than test values under design flow rate condition and large flow rate condition before head suddenly dropping,results are opposite under small flow rate condition,error is minimum under design flow rate condition.As flow rate increasing,firstly,critical cavitation allowance decreases,and then it increases.Predictive values of head and critical cavitation allowance: when it is near design flow rate condition,Schnerr&Sauer cavitation model is closer to test value,when it is away from design flow rate condition,Zwart-Gerber-Belamri cavitation model is closer to test value.It has greater affect when cavitation region is closer to the outlet of impeller.2.Determining methods for promoting cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactorAnalysing cavitation internal flow fields of impeller that are corresponded with cavitation models that more accurately predicts cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor under different flow rate conditions,it can give results as follow: cavitation has little effect on hydraulic performance of the secondary circuit coolant pump of sodium-cooled fast reactor when it occurs on the blade back.However,hydraulic performance of the secondary circuit coolant pump of sodium-cooled fast reactor drops sharply when it occurs on blade working face.Diffuse velocity of cavitation when it occurs on blade working face is larger than when it occurs on blade back surface.Other phenomenon indicates that the closer cavitation field is to impeller outlet,the greater effect of flow field parameters.Cavitation has more effect on the flow field parameters with flow rate increasing;the phenomenon that bubble accumulate near the front cover of the impeller is more obvious.Basing on analysis results of cavitation internal flow field of the secondary circuit coolant pump of sodium-cooled fast reactor and cavitation theory of centrifugal pump,cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor can be improved from three optimizing aspects of blade inlet position,blade inlet angle and the curvature radius of the inlet part of the front cover plate of the impeller.3.The effect of blade inlet edge position on cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactorGuaranteeing others geometric parameters of the blade being constant,forward moving blade inlet edge.Firstly,the effect of blade inlet edge position on external characteristics of the secondary circuit coolant pump of sodium-cooled fast reactor is judged,and confirming cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor whether promotes.If results is positive,the method that extending blade inlet edge with different degree will be applied to explore the optimum blade inlet edge position of the secondary circuit coolant pump of sodium-cooled fast reactor.The result shows that,the effect of blade inlet edge position on external characteristics of the secondary circuit coolant pump of sodium-cooled fast reactor is unsignificant.Cavitation performance of model pump B increases most,and it ensures smaller expense of hydraulic performance.4.The effect of blade inlet angle on cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactorGuaranteeing others geometric parameters of the blade being constant,just increasing blade inlet angle.First of all,it should be judged that the effect of blade inlet angle on external characteristics of the secondary circuit coolant pump of sodium-cooled fast reactor,and confirming cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor wether cavitation performance whether promotes.If results is positive,the method that increasing blade inlet angle with different degree will be applied to explore the optimum blade inlet angle of the secondary circuit coolant pump of sodium-cooled fast reactor.The result shows that hydraulic performance of the secondary circuit coolant pump of sodium-cooled fast reactor slightly decreases when blade inlet angle increases 3-9 degrees.In order to improve cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor,it that reducing hydraulic performance within acceptable limits is worthwhile.cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor more increases when the blade inlet angle increases within 3 degrees-9 degrees.when blade inlet angle increases 3 degrees.However,head seriously fluctuates when blade inlet angle increases 9 degrees,which affectes stable operation of the secondary circuit coolant pump of sodium-cooled fast reactor.Considering comprehensively,cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor is the best when blade inlet angle increases 6 degrees.5.The effect of curvature radius of inlet part of impeller front plate on cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactorGuaranteeing others geometric parameters of the blade being constant,increasing curvature radius of inlet part of impeller front plate.First of all,the effect of curvature radius of inlet part of impeller front plate on external characteristics of the secondary circuit coolant pump of sodium-cooled fast reactor is judged,and confirming cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor whether promotes.If results is positive,the method that increasing curvature radius of inlet part of impeller front plate with different degree will be applied to explore the optimum increasing curvature radius of inlet part of impeller front plate of the secondary circuit coolant pump of sodium-cooled fast reactor.The result shows that cavitation performance of the secondary circuit coolant pump of sodium-cooled fast reactor is the best when curvature radius of inlet part of impeller front plate is 60 mm.