Solid-Liquid Two-Phase Flow Stability And Fluid-Structure Interaction Analysis Of The Multistage Centrifugal Pump

As a general energy conversion machine,the pump has been widely used in all aspects of social and economic development.This paper takes the multi-level wear-resistant centrifugal pump as the research object.According to the actual size,the complete internal flow channel is extracted,including the inlet section,the outlet section,and the impeller,forward guide blade,and reverse guide blade of different stages.For the solid-liquid two-phase flow transport medium,assuming a certain concentration of solid particles,combined with the SST turbulence model,non-uniform multi-phase flow model and Particle sub-model,it mainly studies the flow law inside the multi-stage centrifugal pump under various flow conditions,and analyzes the influence of the pressure fluctuation in the flow channel on the stability of the rotor when considering the prestress.The following conclusions are drawn:(1)The relative velocity angle of the impeller inlet increases with the increase of the flow rate,causing the position where the flow separation occurs on the suction surface side of the impeller blade to the outlet,and the solid particle volume fraction near the suction surface of the impeller increases with the increase of the flow rate,indicating solid particles gradually concentrate on the suction side of the blade.The flow in the impeller is turbulent at low flow conditions,resulting in a significant slip of the solid-liquid two phases.In the reverse guide vane,as the flow rate increases,the angle of the water flowing into the reverse guide vane from the transition area decreases,the flow becomes more and more turbulent,and the turbulent flow energy gradually increases.(2)In a period of the number of revolutions of the impeller,the periodic pressure fluctuation at each monitoring point is related to the number of blades of the impeller or guide vane.At each flow condition,the main frequency of all monitoring points is mainly concentrated at the low frequency.In general,in the time domain diagram,the main frequency of the monitoring points whose pressure fluctuation periodicity is related to the number of impeller blades is the rotor blade frequency,and the main frequency of the monitoring points whose pressure fluctuation periodicity is related to the number of guide vane blades is the guide blade frequency,and the frequency division rate is an integer multiple of the blade frequency of the corresponding impeller or guide blade.The pressurefluctuation at the monitoring point at the outlet of the impeller was the most violent,and the amplitude of pressure fluctuation was generally larger,and there were a large number of high frequency dividers.The pressure pulsation at the monitoring point in the guide vane is the weakest.(3)In clean water and solid-liquid two-phase media,the maximum equivalent stress is located at the junction of the final impeller blade outlet and the front cover plate,and the maximum deformation occurs at the rear impeller rear cover plate outlet,both of which are biased toward the blade suction side.The natural frequency of the rotor system under solid-liquid two-phase flow prestress may appear to be the same as the internal flow pressure fluctuation frequency division,which should be considered during design.