Research On Optimization Of Impeller And Rotor Dynamics Of Multistage Centrifugal Pump In Chemical Industry

Multi-stage centrifugal pump is a high-lift centrifugal pump with two or more impellers,which is widely used in chemical,electric power,fire protection and other fields.Compared with the single-stage centrifugal pump,the internal flow field is more complicated,including the flow changes caused by the periodic change of the relative position between the internal rotor and the stator and the pressure field boundary conditions.At the same time,due to the high-speed operation of the rotor,its The force of the shafting rotor system is complex and often accompanied by vibration,which may cause shock damage to the equipment and seriously affect the safe and stable operation of the multi-stage centrifugal pump.In this paper,the GRD-100 chemical multistage centrifugal pump is the research object,the impeller is optimized hydraulically,and the dynamics of the shaft rotor components are studied.The main research work and conclusions are as follows:(1)Introduced the research status of multi-stage centrifugal pumps at home and abroad,compared the development history of multi-stage centrifugal pumps at home and abroad;introduced the research status of rotor dynamics at home and abroad,and summarized the development of the theoretical system of rotor dynamics.History and several analytical methods.(2)The multi-stage pump fluid domain model was modeled with UG software.The grid was divided by ICEM CFD and the independence was verified to obtain a suitable number of grids.Based on CFX,the internal flow field was calculated with a constant value,and the results showed The head and efficiency simulation results and experimental results have small errors.(3)Based on the Central Composite Design-response surface optimization analysis method,the four key design parameters of the multi-stage pump impeller: the number of impeller blades,the diameter of the impeller,the blade wrap angle,and the width of the blade outlet are optimized.The results show that the number of impeller blades and the impeller diameter have a more significant impact on the impeller head than the blade wrap angle and blade exit width.The regression model of the impeller head was obtained,and the deviation between the predicted value and the simulation result obtained by substituting the original pump impeller design parameters was2.4%,and a set of optimized impeller design parameters was obtained and modeled by increasing the head as much as possible.(4)Based on the results of steady simulation calculations above,the internal unsteady flow of the impellers and guide vanes of different stages of the multi-stage pump under different flow conditions is simulated and calculated,and the three operating conditions of 0.8Q,Q,and 1.3Q are simulated.The pressure pulsation analysis and radial force analysis are carried out.The results show that the guide vane and impeller play a leading role in the pressure pulsation in the other flow channel;the higher the order,the greater the fluid pressure on the impeller and the guide vane;large flow conditions The amplitude of the pressure pulsation below the point is greater than the small flow operating point;the amplitude of the pulsation frequency in the guide vane is greater than the amplitude of the pulsation frequency in the impeller due to the influence of dynamic and static interference;the radial force decreases with the increase of the flow rate.The radial force on the impeller is affected by the number of impeller blades.(5)The statics analysis of the barrel and impeller of the multi-stage pump shows that: when the maximum allowable working pressure is 24 Mpa,the maximum stress value of the multi-stage pump barrel is 401.43 Mpa;each level under different flow conditions The impeller deformation is concentrated at the exit position of each flow channel,and the deformation of the rear cover plate is larger than that of the front cover plate,showing a trend of first decreasing and then increasing with the increase of flow;the closer to the impeller edge under different operating conditions,the greater the stress,the maximum stress value As the flow rate increases,it first increases and then decreases.(6)The "dry" and "wet" modal analysis of the multi-stage centrifugal pump shaft system rotor system are carried out.The results show that: in the "dry state" analysis,after adding prestress to the shaft system rotor,the first six natural frequencies of the structure are all There have been different degrees of improvement;the natural frequency of the structure in the "wet state" is reduced by about 14% compared to the dry state;the Campbell diagram shows that the first critical speed of the pump in the "wet state" is 6399.6 r/min,which deviates from it.More than 20% of the working speed,the multi-stage centrifugal pump shaft system rotor will not resonate.