| The clearance layer leakage between the pump cover and the impeller is the main reasonthat the performance of the low-specific speed centrifugal pump with the semi-open impeller islower than that of the common centrifugal pump. So it has an important significance toinvestigate the effects of different tip clearance on the performance of low-specific speedcentrifugal pumps. In this paper a low specific speed centrifugal pump of semi-open impellerwith backward blades is studied to investigate the influence of different tip clearance on theperformance alteration of centrifugal pumps. Numerical simulation, performance prediction andexperiment of characteristic performance are carried out on the centrifugal pump under fourdifferent tip clearances. The main contents are listed as follow:(1) The three-dimensional models of the inducer, semi-open impeller with backward bladeand volute are completed by using Pro/e software. The module which is IGG/AutoGrid in thesoftware of NUMECA is used to generate the grids of whole computational domain at differenttip clearances which are0.6mm,1.2mm,1.8mm and2.4mm.(2) The numerical simulation for inner flow field of the low-specific-speed centrifugalpump with semi-open impeller of backward-blade under four values of tip clearance is donewithin all the flow range. The effects on inner flow field of centrifugal pump and performanceunder different tip clearance are analysed. The loss of energy in the flow passage at design pointthe location and the shape of the backflow, secondary flow and other unstable flow factors arediscussed.(3) The characteristic-performance experiment of semi-open centrifugal pump withbackward-blade under four values of tip clearance is carried out. The effects on thecharacteristic performance of low-specific-speed centrifugal pump under different tipclearances is discussed. By comparing the tests and calculation results, the viability of thesimulation method and the accuracy of the result are proved. |
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