Hydraulic Optimization And Rotor Stability Analysis Of High Speed Well Pump

The high speed well pump has the advantages of light structure and superior performance.By increasing the speed of the pump,the hydraulic performance is greatly improved,and the volume and weight of the pump body are also reduced,which greatly reduces the manufacturing cost.In recent years,high speed well pumps have been widely used in various industries such as farmland irrigation,urban water supply,and energy extraction due to the special properties.However,the substantial increase in speed has put forward higher requirements on the hydraulic design,rotor stability and overall machine reliability of high speed well pumps.This paper takes 100QJ10 high speed well pump as the research object,and uses orthogonal optimization experiment to obtain the best performance model.Steady and unsteady calculations are performed on the optimized models at different speeds,and the external characteristics and radial force trends of the optimized models at different speeds are obtained.Using SAMCEF software,the critical speed and vibration mode of the optimized model rotor under “dry and wet state” are analyzed.At the same time,the effects of unbalanced mass and phase,start-up time,mouth ring dynamic characteristics and fluid excitation force on transient response and harmonious response are studied.In addition,the reliability of the numerical simulation results is verified through external characteristics tests on the initial model and the optimized model.The main work done in this article are:1.The current research status of the deep well pump,the high speed pump and the rotor dynamic at home and abroad was summarized.The background and engineering significance of research on the high speed well pump were analyzed.And the main research content of each chapter was pointed out through the research technology roadmap.2.Orthogonal optimization test of the three-stage simplified model of the 100QJ10 high speed well pump was done by ANSYS software.The orthogonal model with 7 factors and 3 levels was adopted to obtain the optimal model under the standard conditions.The optimal model was used for the numerical simulation of the full flow field of the nine-stage pump body.At the same time,the external characteristics of the initial model and the optimized model were compared with the test data to prove the reliability of numerical simulation.The results show that there is no vortex in the pump body of the optimized high speed well pump,the energy loss is small,and the pressure difference between the inlet and outlet is large,its head has been greatly improved.The blade outlet angle and the chamfer angle of the impeller outlet have a great influence on the efficiency and head of the high speed well pump.3.The optimization model was numerically simulated in five working conditions under five different speed schemes.And the effects of different running speeds on the performance of the model were analyzed.The unsteady calculations of the models at 3000r/min,6000r/min and 9000r/min were carried out to obtain the radial force distribution.The results show that the higher the rotating speed,the better the hydraulic performance.However,excessively high speed will increase power and radial force,which is detrimental to the stability of the rotor system.4.The SAMCEF software was used to calculate the critical speed of the rotor parts of the high speed well pump in one-dimensional,two-dimensional and three-dimensional models.And the critical speed and vibration mode under different models were compared and analyzed.The results show that there is no significant difference in critical speeds under the three models.After considering the sealing force under “wet state”,its critical speed increases slightly and the vibration amplitude decreases.This shows that the sealing force of the mouth ring can improve the stability of the rotor.5.Through the transient response analysis,the impellers of the high speed well pump rotor system were compared,and it was found that the maximum radial displacement occurs at the fourth-stage impeller.Taking the fourth-stage impeller as the research object,its change rules under “dry state” and “wet state” were studied respectively.By changing the unbalanced mass and start-up time under “dry state”,it was found that the unbalanced mass has a greater influence on the stability of the rotor system,and the radial displacement increases as the unbalanced mass increases.In addition,starting too fast may cause unstable operation of the high speed well pump.Under the "wet state",it was found that the impeller ring has a positive effect on the stability of the high speed well pump rotor system,which can effectively reduce the radial displacement.After the excitation force is loaded,the stability of the rotor is greatly reduced,the radial displacement has been significantly increased,and the axis trajectory has become more chaotic.6.The harmonic response analysis of the high speed well pump was carried out.The acceleration amplitude and displacement amplitude of the high speed well pump under “dry and wet state” were solved separately.Under the “dry state”,comparing the impellers at all levels,it was found that the maximum amplitude occurrs at the fourth impeller.The vibration amplitude of the fourth-stage impeller under different unbalanced mass phases was studied.Under the “wet state”,the effect of the sealing force of the ring was considered on the fourth-stage impeller.The results show that the unbalanced mass phase has a certain effect on the stability of the rotor.As the phase increases,the vibration amplitude decreases.The existence of the mouth ring greatly improves the stability of the rotor system,reduces the displacement amplitude and acceleration amplitude,and the first-order eddy frequency is also increased.