Numerical Simulation And Experimental Study On Deep-well Pump Under Different Rotating-speed

As a mechanical equipment that provides high-lift liquids,deep-well pumps have been widely used in all areas of national production.Due to the fact that the diameter of the pump body is often limited by the diameter of the deep,the number of the deep-well pump`s stage is usually increased to meet the user’s head demand.Which leads to a larger axial length,and then to the inconvenience of pump`s installation and maintenance.In order to improve the single-stage head of the deep-well pump and shorten its axial length,enhance its running speed has become a major trend in deep-well pump design.In this paper,UG 8.0,ANSYS CFX 14.5 and other software were used as a tool to complete the hydraulic design and numerical calculation of 100QJ20 type deep-well pump.And through the performance test,the accuracy of numerical calculation was verified.The main research work and results are summarized as follows:(1)The development history of deep-well pump products was reviewed,a brief summary of the related research on hydraulic design was made,and the research status of pump internal flow and pump speed changing in recent years were introduced.(2)Based on the proportional scaling design method,the hydraulic design of the 100QJ20 type deep-well pump was completed.The initial model(150QJ36 type deep-well pump)and the design model were respectively 3D modeled.Also,the grids of their each calculation domain were devided.At last,the numerical calculation of them were completed respectively by the ANSYS CFX software.The external characteristics of the two models can meet the similarity conversion criterion well in the range of 0.4 ~ 1.6 times rated flow.The distribution of their internal flow field have strong similarity and slight difference.Finally,the accuracy of the numerical calculation was verified by the experimental study of the 150QJ36 type deep-well pump.The numerical prediction of the head and the power is slightly lower than the test result,the efficiency is slightly higher than the test value,and the variation trend of them is basically the same with the change of flow.Which certifies the high precision of the numerical simulation in this paper.(3)The numerical simulation on 100QJ20 type deep-well pump in multiple conditions under different speed were carried out to achieve the influence of running speed on the performance of deep-well pmp.The head and the power forecast value of the deep-well pump at different rotating speeds basically satisfy the similar conversion criterion,and the pump efficiency is improved with the increase of the rotating speed.Because the disc friction loss does not meet the similar conversion criteria under different speed,and with the increase of speed,the proportion of the disc friction loss in the shaft power declining.(4)Several sets of monitoring points were arranged in the subfields of the deep-well pump model,and the unsteady numerical calculation of the deep-well pump model at three different rotating speeds were completed to obtain the pressure pulsation data of each monitoring point.Through the dimensionless process and fast Fourier transform of the pressure pulsation data,the clear time distribution and frequency distribution of the pressure pulsation were obtained.It shows that the pressure pulsation in the pump has complicated inter-stage coupling and rapping phenomenon.The distribution of pressure pulsation in the pump under different speeds have some similarity,but the frequency of the pressure fluctuation in the pump is higher than that of the low speed.Also,the change of the rotating speed will cause the change of the pressure pulsation phase of some monitoring points.(5)Three different change modes of speed were determined,and the unsteady numerical calculations of the deep-well pump model under them were completed.In the three schemes,the fluctuations of the head during the straight-line acceleration process and the opening-down secondary acceleration are weaker than that of the opening-up secondary acceleration process,and the opening-down secondary acceleration process can first meet the head requirement.During the pump acceleration process,the secondary flow in the impeller flow path will be significantly improved.