Study On The Hydraulic Performance And Internal Flow Of A Large-scale Double-suction Pump

The double-suction centrifugal pumps are widely used in in water conservancy irrigation,industrial water treatment,urban water supply and drainage,inter basin water transfer and other fields because of their unique features such as large flow rates,high pump head and easy in maintenance.It is of great significance to improve the hydraulic efficiency of large-scale double suction pump due to its high consumption of large-scale double suction pump.In the present study,a double-suction pump was designed according to the design requirements and the Computational Fluid Dynamics(CFD)method was used to conduct in-depth study on the hydraulic performance and internal flow of the double-suction pump.Besides,the influence of complex flow structure on the hydraulic performance of double suction pump was discussed.Then,in order to improve the stress and pressure pulsation characteristics of the main flow passage components,a staggered impeller was proposed to investigate the influence of the impeller structure on the stress and pressure pulsation of the flow passage components of the double-suction pump.Main work and conclusions obtained in the present study are as follows:(1)The design of a large-scale double-suction pump was conducted based on the design parameters.The numerical method was used to predict the hydraulic performance and internal flow of the model pump.The relationship between the complex flow structures and hydraulic performance of the large-scale double-suction pump was also discussed.(2)The internal flow of the double-suction pump under different operating conditions was analyzed systematically.The results show that the pressure distribution is relatively uniform under the design condition.There is no obvious complex flow structures and high turbulent kinetic energy area occur inside the pump.The energy loss is the smallest under the design condition,and the hydraulic efficiency of the pump is the highest.(3)Under small flow rate condition,there are obvious low pressure area and high turbulence kinetic energy area occur near the front cover plate at the impeller inlet,which indicates that the flow loss here is large.This low pressure area is also an important factor to induce cavitation at the impeller inlet.Obvious flow separation phenomenon and high turbulence area are observed at the tongue of the volute under large flow rate conditions.(4)The staggered impeller has little effect on the hydraulic performance of the double-suction pump,but it can effectively improve the stress of main flow passage parts of the pump,and the radial force of the impeller is reduced.Under small flow rate condition,the radial force on the impeller can be reduced by 30% at most.Within a rotation cycle,the radial force distribution on the impeller is more uniform,which is conducive to improving the vibration performance of the whole pump and improving the service life of the pump shaft.Moreover,the staggered impeller is of great help to restrain the pressure pulsation of the double-suction pump and improve the vibration and noise characteristics of the double-suction pump.