A Blood Pump Design Of The Axial-flow Type Buttressed By Pivot Under The Dynamic Pressure Of The Bloodstream

Heart failure caused by cardiovascular disease has become one of the main reasons of human death.Currently,heart transplantation is the most effective clinical method to treat heart failure.However,due to the lack of donors,a large number of patients died before suitable donors had been found.The invention of blood pump provides a new way for the treatment of heart failure.A supporting pattern which combined blood dynamic pressure and Pivot bearing is promoted with respect to the friction of mechanical bearing used in the second-generation blood pump and the large size and heating problems of the magnetic bearing used in the third-generation blood pump.This research proposed an axial flow blood pump superposing blood dynamic pressure and Pivot bearing.Firstly,key parameters of the axial flow blood pump were optimized by the method of CFD(Calculation Fluid Dynamics).Secondly,numerical simulation analysis and hemolysis prediction towards the optimized blood pump were implemented.Lastly,the optimized blood pump was manufactured and the hydraulic characteristics tests were conducted through building a cardiopulmonary bypass experiment platform.The main results of this paper are as follows:(1)Structure parameters of impeller and the front and back jockey wheels of the axial flow blood pump were optimized according to the theories of axial flow blood pump design principles,cylindrical irrelevance assumption,Standard k-? turbulence model and circular method.Then,relevant parameters of axial flow pump were determined to meet the requirements of structure with the volume of the pump as small as possible.(2)Four parameters including the amount,height,inlet and outlet angles of blades were optimized by establishing a duct model and using the analysis of calculation fluid dynamics.Then,a numerical simulation analysis was conducted on the optimized model and reached a conclusion that this optimization plays a positive role in enhancing the hydraulic characteristics of the axial flow pump.(3)A supporting pattern combing Pivot bearing and dynamic pressure was designed,and the blades' radial force during the work of the blood pump was analyzed through the calculation fluid analysis which proved that the supporting pattern designed by this research could reduce Pivot bearing's radial load and realize a fine support to axial flow pump due to the bearing force produced by its dynamic pressure.(4)A hemolysis prediction model was established through power function model involving hemolysis and shear stress as well as exposure duration raised by Giersiepen.Particle tracking method was used to predict the hemolysis performance of the blood pump which showed that the hemolysis value of the axial flow pump is relatively smaller and generated less harm to the hemocyte.(5)The optimized blood pump was manufactured and assembled according to the optimized parameters.Experiments were conducted after building the extracorporeal circulation simulation experiment platform.Results showed that a good agreement between the experiments and simulations had reached which verified the reliability of numerical simulation analysis and the rationality of the design of this kind of blood pump.It proved that computational fluid dynamics could accurately analyze the blood pump flow channel,optimize the blood pump and shorten the research period.The Pivot bearing under the proposed blood dynamic pressure has the advantages of small friction and small size,which better solved the existing problems of blood pump.