The Flow Numerical Simulation In The Centrifugal Pump Based On CFD

The centrifugal pump is widely used in the national economical departmentssuch as water supply, agriculture project, solid granule transportation project, oiland chemical industry, aviation and spaceflight project, energy sources project,vehicle engineering. With the development of the technology and the industry,people's demand is more and more high for the design of the centrifugal pump,such as more efficiency, no over loading. Obviously the current theory and methodsfor the centrifugal pump is not satisfied this demand. Nowadays CAD/CAE/CAMis widely applied and spreaded in many fields abroad. With advanced computertechnology, the engineers can not only improve the design quality of products andshorten the design periods, but also optimize the design projects and ensure thereliability of the products. Compared with the foreign countries', it is very differentin technogical index in the centrifugal pump. So our enterprises producing thecentrifugal pumps need to research a saving energy and high efficiency product toimprove the level of the technology and attach ourselves to compete with foreignenterprises.With the development of technology, Computational Fluids Dynamics shortenin CFD has been one of the three methods (theory, experiment, computation) thatresearch fluids and solve real engineering issues. It is important for improvingpump efficiency to research the inner flow in the whole pump. In the recent years,CFD technology is more and more applied to the 3D flow analysis in fluid mechine.People have also been paying more and more attention to the inner flow in thewhole centrifugal pump. The core is using 3D numerical technology to simulate thereal flow when running. Mathematics methods can overcome the diffculties in thedesign of the centrifugal pump, also may display the area of the test. Meanwhile,the proper model can reduce the costs and shorten the periods in the design of thecentrifugal pump.A precise and reliable finite cell model was the foundation of the fluid in cellmethod analysis. The results of the simulation are related with the finite cell model.However, in the real issues,the shape of the part of the pump, especially the vaneof the impeller and the lumen of the volute is very complex. So I make the complex shape by the 3D design software CATIA. According to the shape I made out themodel of the whole fluid in the centrifugal pump.For the numerical sumulation, I used the precessor software GAMBIT that isthe part of the commercial CFD software FLUENT to mesh the model of the wholefluid. This step is to divide the computational model into the finite cell model.Because the structure of the whole fluid is very complex and the dimension is large,I used the Tgrid to mesh it. The interval size is 4mm and the quality of meshes isproper. The water in the centrifugal pump is viscous, so I chose the standard k ? ?turbulent mode as the simulating model after contrasting all of the viscous modelsin the FLUENT. We can simulate the swirl, the secondary flow, the wake and someother flows in the inner of impeller by the standard k ? ? turbulent mode which iswidely used in the viscous fluid. According to the steps of CFD, I may computeafter defining the boundary conditions. There are three methods in the FLUENT. Iadapted the SIMPLE as the pressure and velcolity coupling. For accelerating theconvergence I used the under relaxation factor. By montoring the outlet pressureand the residual, I got the simulation result after multi-iterating.As the results of the simulation including velcolity and the pressure of theflow feild in the ZA40-250 centrifugal pump in the standard working conditons, theflow from simulation coincided with the theory analysis and accorded with thedesign principle of the inpeller and volute. In the standard working conditions, theflow in the inlet is steady, the relatively low velcolity and the pressure start toincrease from inlet of the impeller. When the water flows away from the outlet ofimpeller, the velcolity increase to the maximum. After the water goes into thevolute, the velcolity starts to fall. When the velcolity reduces to the minimum in theoutlet of the volute, the pressure of the flow field reaches to the maximum.Simulating the flow feild in the other working conditions including thenon-standard condition, I found out many important phenomena of the flow. Thepressure and velcolity of the flow field reduces with the flux increasing. In anyworking conditions, the velcolity vectors are significantly different in the threechannels of the impeller. The variational grades near the duct are low. The pressureof the three channels in the impeller is unsteady. In the volute, some part of flowareas especially in the throat exist high pressure.The paper contrasted the results of the simulation with the test one and demonstrated the method based on CFD is right and reliable. Observing theperformance curves of the simulation and the test, I educed that the overallperformance curves of the pump obtained by numerical simulation and theexperimental data have good coincidence in the design load situation. The power ofsimulation is less for 22% than the test.The optimized computation and simulationallow the error in the extent. In the other operation situations the results also havesome little errors. At last I found out the reasons and made the prospect.