The Experiment Research And Numerical Simulation On The Unsteady Internal Flow Of A Small Centrifugal Model Pump

Miniature pump has attracted more and more attention due to its special varyingsizes as well as its promising future for application. Particularly, the miniature pumpused for medical equipments are studied widely since its role in saving cardiac's life.The performances of miniature pump is determined by its internal flow, therefore thekey to research on miniature pump lies in the internal flow pattern of the pump. Thisthesis focuses on the internal flow of a centrifugal model pump, which also provides afundamental work for advanced research about optimizing design in future.Both experimental measurement and numerical simulation are engaged in thiswork. A centrifugal model pump test rig is built in order to conduct PIV measurement.The test, involving the technology of index match and fluorescent, is for acquiringflow pattern in a fixed rotational speed, the velocity and stress distribution of the flowfield are thus obtained. In order to get more information about internal flow, SST k-ωturbulence model and DES method are applied to simulate3D whole passage flow.The external characteristic and internal flow pattern of the model pump are calculated.According to comparison with experimental data, the unsteady simulation is provedto be relatively accurate in predicting the flow status in the centrifugal model pump.And results show that unsteady flow phenomenon such as "stationary stall" wouldemerge at small flowrate working condition while the flow is stable in conditions ofdesigned and large flowrate working conditions. Maximum wall shear stress nearimpeller wall appears to be at the head of a blade, and the value would increase withthe rise of the pump discharge.Another hotspot in the field of blood pump research is how pulse flow could begenerated in the impeller pump to help patients in recuperation. In this thesis, amethod of changing rotational speed of impeller periodically as the pulsation workingcondition is developed to realize pulse output of both discharge and head, which isstudied through experiment and numerical computation. The performance of thepump in pulsation working condition is obtained, indicating that the model pump could produce desired pulse flow in such condition. Furthermore, flow patterns atfour testing points in pulsation working condition are achieved, in addition withanalysis of stress in testing region. After that, by adding a source term of volumeforce as well as rotational speed adjustment macro and a User Defined Functions(UDFs) program is developed based on the software FLUENT to calculate theinternal flow of the pump in pulsation working condition. Results show that changesof maximum shear stress on inner wall of a pump go with changes of speed.Moreover, the maximum value of static pressure in the volute change in a same waywith speed, but speed changes have no significant impact on the static pressure in thepump intake.