Design And Numerical Optimization Research On Multistage Centrifugal Pump With Middle Split Casing

With high power,large flow rate and high head,multistage centrifugal pump with middle split casing is widely used in petrochemical,agricultural irrigation and thermal power and so on.But the correlational research is scarce.Many technological problems have yet to be solved during the development process.According to the practical situation,the design technology of energy saving and reliability of multistage centrifugal pump with middle split casing of great significance to the process of domestication of similar products,energy saving and the improvement of technological level.In this paper,numerical simulation and performance tests were adopted to study the double suction three-stage split case centrifugal pump,the design approach of transition flow channel be highlighted.The research results will enrich and develop the multiple-stage centrifugal pump design theory and method.The main work and research results of this dissertation are follows:1.The research states of multistage centrifugal pump with middle split casing,inner flow condition and pressure pulsation were reviewed integrally,the research contents in this paper were set forth.2.According to the require,the structural style of pump was confirmed,meanwhile,Based on theory of centrifugal pump,the hydraulic design of impeller,volute and transition flow channel be finished.3.The steady-state and unsteady numerical simulation of the pump was carried out by using ANSYS software.The external properties of the pump were predicted and the internal flow was analyzed.The results shows that the flow state in the suction chamber and impeller is well,and the flow disorder occur in the transition flow channel and the pressurized water chamber.The main hydraulic loss in large flow condition is obviously greater than in other flow rates,and the loss of a single flow channel accounts for 5.5% of the rectification loss.The research of pressure pulsation in the transition flow channel shows that the pressure pulsation in the second transition flow channel is greater than that in the first transition flow channel4.By improving the structure parameter which include the area of the forward channel,volute tongue,wrap angle,guide plate,the performance of the pump is optimized,At the same time,analysis the effect of these structural parameters on pump performance,the results showed that:(1)The area of the forward channel has a great influence on the head and efficiency which in the large flow condition,appropriately increasing area of forward channel to the benefit of broaden the efficient operation range.(2)Compared with the pump without tongue,the velocity loop at the exit of the reverse channel is reduced and the lift is obviously increased.(3)Compared with the90°wrapping angel channel,the head of 135°wrapping angel channel decreases slightly,a lower efficiency at the large flow condition and a higher efficiency at the design condition.(4)After the addition of the guide plate,the flow in the reverse channel becomes more stable,and the efficiency and head performance are improved.5.Adopt the method of numerical simulation,the internal flow,pressure pulsation and radial force of the optimized model under three typical flow rates was analyzed.Research shows that the internal flow field is improved compared with that before optimization.Lift was significantly improved,and the efficient area was significantly widened,and at the same time,the pressure pulsation in the reverse channel was significantly reduced,but the radial force was equivalent to that before optimization.6.The optimized centrifugal pump was manufactured and tested,and the performance data of the multistage centrifugal pump with middle split casing was obtained.The results showed that the performance indexes met the expected requirements.Finally,the numerical simulation results are compared with the experimental results to verify the reliability of the numerical simulation.