Research on the Mechanical Injure Principle of Blood and on the Structure Optimization of the High-Speed Spiral Blood Pump
|School||Central South University|
|Course||Mechanical Design and Theory|
|Keywords||spiral blood pump blood mechanical injure optimization|
In high speed spiral blood pump, the hemolysis problem, which iscaused by the mechanical injure of blood, especially the mechanicalinjure of red blood cell, has been disturbed medical and researchpersonnel. It has become the shackle of the further developement and theclinic application of the high speed spiral blood pump. Thus, the study onthe blood mechanical injure principle in the running pump, and thesearching on the red blood cell mechanical injure rule, will providecorresponding theory gist and experiment reference for the optimizationof the blood pump design.Combining the designed embedded spiral blood pump, the impactinjure, the press fragmentation, the shear avulsion, the turbulencefragmentation and other red blood injure factors in the high speed spiralblood pump has been analyzed systematically. The work on the theory,the simulation, and the experiment has been shown as follows:1. The blood spiral flow character in annular space at low shear rateand at high shear rate has been study. The expresses of velocity and fluxare presented. The relevant parameters’ influence on the blood spiral flowcharacter has been analyzed. The blood spiral flow rules in annular spacehave been obtained. The complex mechanical environment of red bloodin the high speed spiral flow field, and the various mechanical charactersof red blood cell have been analyzed.2. The one dimensional and two dimensional nonlinear process of theimpacting between red blood cell and solid wall have been analyzedtheoretically. The corresponding fluctuate equation and numericalsolution are presented. The varying rule of all the parameters, such aspeak value pressure, side shoot speed, critical contact angle, the impactpressure layout, with respect to the impacting speed has been analyzed.The red blood cell film fragmentation principles and conditions areanalyzed by using the theory of sphere surface wave. 3. The red blood cell shear fragmentation, press fragmentation andturbulence fragmentation mechanisms have been analyzed by using thetheory of waterpower rotated flow field, thin wall sphere shell and liquiddrop fragmentation. The results indicate: In the high spiral flow field,when the pressure gradient is large enough, the red blood cell may beexpanded and broken by conquering the surface tension of cellmembranous. The shear fragmentation caused by laminar flow is not themain factor, while the turbulence fragmentation is the main reason ofcausing the blood pump hemolysis.4. The divisions of velocity, pressure, stress and the turbulence effectin the designed embedded spiral blood pump have been simulated andanalyzed by using the multiphase suspend body CFD simulationtechnology. The optimization of the blood pump impeller design has beencarried out by using the CFD simulation results and the velocity triangle,Euler power methods. Furthermore, the CFD simulation results havebeen contrasted and analyzed.5. The different blood samples at different impact speeds anddifferent shear ratios have been macro-analyzed and micro-analyzed byusing blood rheometer and digital laser microscope. The experimentsresults indicate: The critical impact velocity of the red blood cellfragmentation is about 6 m/s. The red blood cell injure caused by theshear flow field is more severe than that caused by the impact. Theformer should be regarded as the main considering factor of thehemolysis in the high speed spiral blood pump.