Research On The Influence Of Particle Parameters On The Performance Of Low Specific Speed Centrifugal Pump

As a general-purpose liquid conveying and lifting equipment,low specific speed centrifugal pumps are widely used in different fields due to their small flow and high head characteristics.In addition to the liquid phase,there will also be a certain amount of solid phase in the transported medium,which not only makes the complex flow inside the centrifugal pump more difficult to predict,but also severely wears out the flow parts and affects the stability of operation.If things go on like this,it will not only shorten the life cycle of the low specific speed centrifugal pump,but also cause it to run under partial working conditions for a long time and cause energy waste.Therefore,the influence of the solid-liquid two-phase medium on the internal flow of the low specific speed centrifugal pump still needs further study.Through a brief summary and summary of the current research status,it is found that the existing series of changing particles and concentrations have an impact on the solid-liquid two-phase flow field of centrifugal pumps.The research direction of the research is still more common reasons and working principles.The conclusions are as follows.(1)Numerical simulation of low specific speed centrifugal pump under clean water conditions is carried out,and its hydraulic characteristics are obtained.At the same time,the internal velocity,pressure and turbulent kinetic energy distribution law were analyzed to verify the rationality of the model design.(2)The constant constant value simulation of solid-liquid two-phase flow was carried out under 10 particle concentration conditions and 36 particle size conditions,and it was found that the influence curve of particle size on the lift and efficiency of the centrifugal pump accorded with the change trend of the logarithmic function equation y=alog(x)+b.The influence curve of particle concentration on the lift and efficiency of the centrifugal pump accords with the change trend of trend of the inverse proportional function equationy=a/(bx+c)+d.Some solid-phase media with particle size and concentration will cause the head of the centrifugal pump under solid-liquid two-phase conditions to be temporarily higher than the head under clear water conditions,but the solid-phase medium will cause the centrifugal pump efficiency to drop significantly,and the particle concentration ratio is low.The influence of the hydraulic performance of the rotational speed centrifugal pump is higher than the particle size.The particle distribution on the suction surface of the blade is more than that on the pressure surface of the blade,and the particles attached to the rear part are the most but the solid phase volume fraction at the outlet is smaller.The distribution of particles on the front cover plate is more than that on the rear cover plate,and the diaphragm tongue of the volute is the main wear part.The simulation calculation of the non-constant value of solid-liquid two-phase flow of a low specific speed centrifugal pump shows that the pressure pulsation is mainly caused by the blades periodically passing over the diaphragm.The pressure pulsation in the volute mainly appears at the leaf frequency and its multiplier,and the peak of the pressure pulsation amplitude appears at 1 leaf frequency.The pressure pulsation of the blade mainly appears in the low frequency range.The radial force of low specific speed centrifugal pumps is studied,and the results show that the asymmetric structure of the volute is the main reason for the radial force.With the increase of the particle size,the radial force on the impeller continues to decrease,and the radial force on the volute and diaphragm continues to increase.With the increase of particle concentration and the flow rate of the centrifugal pump,the change law of the radial force on the impeller,volute and diaphragm is completely opposite to the change law of the radial force when the particle size increases.