| Implantable rotary blood pump is one of the effective ways to treat heart failure.Compared with rotary blood pump using mechanical bearings,the third generation of blood pump using suspension support has significant advantages in improving blood compatibility.Adopts hydraulic suspension way of blood pump with suspension stability is good,the advantages of compact structure and low energy consumption,but narrow clearance between impeller and the pump shell surface easily blood damage,as a result,when designing the blood pump hydraulic suspension structure need to comprehensive analysis of suspension stability and blood compatibility,make the blood pump stable suspension with good blood compatibility at the same time.The blood pump in this topic adopts magneto-liquid coupling suspension support mode,and the negative stiffness generated by magnetic levitation mode in the axial direction is not conducive to the stable suspension of the blood pump impeller.Therefore,by analyzing and summarizing the existing hydraulic suspension structure of the blood pump and combining with the structural characteristics of the blood pump in this topic,the negative axial stiffness is eliminated by setting dynamic pressure bearings in the axial direction to ensure the suspension stability of the impeller.The flow field of the blood pump was numerically simulated by computational fluid dynamics software,and the distribution characteristics of the blood pump flow field and the pressure boundary value of the fluid suspension structure with the initial scheme were obtained.The flow field in the fluid suspension structure of blood pump was made reasonable assumption,and the corresponding Reynolds equation was established on the basis of the assumption.The Reynolds equation was transformed into the boundary fitting coordinate system through coordinate transformation,and the Reynolds equation was solved by the central five-point difference method.Matlab Appdesigner is used to build the calculation software of the bearing capacity and stiffness of the hydraulic suspension structure of blood pump,and solve the bearing capacity and stiffness corresponding to different structural parameters of the hydraulic suspension structure of blood pump,and analyze the influence of the parameters of the hydraulic suspension structure on the bearing capacity and stiffness.Orthogonal experiments were designed to explore the significance of the influence of hydraulic suspension structure parameters on the bearing capacity and stiffness.The supporting force and stiffness measurement platform of hydraulic suspension structure was designed,and the validity of suspension stability research method was verified.Shear stress model,hemolysis model and blood damage calculation method were established to study the blood compatibility of hydraulic suspension structure of blood pump.Fluent was used to simulate the flow field of the fluid suspension structure of the blood pump.The discrete phase model（DPM）was used to obtain the shear stress and exposure time of red blood cell particles in the flow field of the fluid suspension structure,and the hemolysis values of the fluid suspension structure under different structural parameters were calculated.Orthogonal experiments were designed to study the significance of the influence of different structural parameters on the blood compatibility of the hydraulic suspension structure of blood pump,and to analyze the influence rules of the width ratio,depth and clearance of the tank on the blood compatibility of the hydraulic suspension structure of blood pump.Combined with the results of numerical simulation of the suspension stability of the hydraulic suspension structure of blood pump,the parameters of the hydraulic suspension structure of blood pump with good suspension performance and blood compatibility were obtained.In order to verify the suspension stability and blood compatibility of the fluid suspension structure of blood pump,a blood pump prototype with titanium alloy shell was fabricated.The suspension stability experiment was designed on the basis of the in vitro simulation circulation device set up by the research group.External disturbances of different pressures and different frequencies were added to the blood pump to observe the suspension stability of the blood pump under different external disturbances.The in vitro hemolysis experiment was designed to build an in vitro hemolysis experiment platform simulating the human blood circulation system,and the blood compatibility of the designed fluid suspension structure of the blood pump was studied,laying a research foundation for improving the operation stability and blood compatibility of the blood pump. |
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