Hydraulic Performance Optimization Of Volute Centrifugal Pump And Pressure Fluctuation Analysis

With the continuous progress of science and technology,energy and environmental issues are getting more and more attention and the country is increasingly advocating energy conservation and emission reduction,which puts forward higher requirements on the design optimization and operation stability of centrifugal pumps,so it is of great significance to carry out optimization research on pumps for resource conservation。In this paper,both single volute and double volute centrifugal pumps were taken as the research objects,and used numerical simulation calculation methods to investigate the effect of volute structure parameters on pump performance through orthogonal experiments.Through cavitation numerical simulationm,studied the influence of different impeller structure forms on the cavitation performance;and the influence of different impeller and volute structure and different flow conditions on the pressure fluctuation is studied by the unsteady numerical simulation.Following are the mian contents and conclusions of this paper:(1)Taking a single volute centrifugal pump as a prototype object,CATIA software was used to perform three-dimensional modeling of inlet and outlet pipe,impeller,volute,shroud and hub cavities,and the different working conditions numerical simulation was performed in ANSYS-CFX.The simulation results show that the main losses in the volute are concentrated in the cut-water area and the diffuser pipe section。(2)On the basis of the prototype single volute pump,numerical simulation method was used to design a new type of double volute pump.The orthogonal test was used to study the effect of the main structural parameters of the volute on the hydraulic performance.The results show that the proper throat area is helpful for the matching of impeller and volute.For medium-to-high specific speed centrifugal pumps,increasing the diameter of the volute base circle and the placement angle of the cut-water will help improve hydraulic efficiency,and reducing the thickness of the vane will significantly improve hydraulic efficiency.(3)The cavitation numerical simulation of the prototype pump was performed under different working conditions(0.5Q_d、0.8Q_d、1.0Q_d、1.3Q_d),and the cumputed NPSH_c value was obtained and compared with the experimental data.The results show that the simulation value agreed well with the experimental value.According to the numerical simulation results of cavitation for different blade numbers and blade inlet forward,it can be known that reducing the number of blades and blade inlet forward can optimize the cavitation performance,and the effect of reducing the number of blades is more obvious.(4)Based on the non-steady-state numerical simulation of centrifugal pumps with four structures of six-blades single volute,six-blades double volute,seven-blades single volute and seven-blades double volute under different working conditions,the time-domain data and frequency-domian data obtained by Fast Fourier Transform(FFT)of different monitor points have been extracted to analyse the pressure fluctuation characteristics in both single volute and double volute.the calculation and analysis results shows that the main frequency of the pressure fluctuation in the volute is the blade pass frequency,and the volute cross-section area has an important influence on the intensity of the pressure fluctuation around volute circle.The cut-water area is greatly affected by dynamic and static interference,The pressure fluctuation intensity in the middle of vane area is lower than that in the both sides,The main frequency of the pressure fluctuation in the inlet and outlet pipelines are both the blade pass frequency,and the intensity of the pressure fluctuation in the outlet pipeline is much greater than that in the inlet pipeline,The influence of the double volute structure on the pressure fluctuation intensity in the outlet pipeline with different blade numbers is different,compared with the single volute,the double volute structure increases the pressure fluctuation intensity in the outlet pipeline under the condition of six blades and reduces the pressure fluctuation intensity under the condition of seven blades...