The Annulus Flow Field Analysis And Structure Optimization Of The Embedded Axial Blood Pump

In recent years, the treatments of terminal heart failure have become enormous challenges of cardiovascular medical and surgical clinic. Because of the limitations of medication and surgery, as well as the shortage of donor’s heart, the development of cardiac mechanical circulatory support devices (artificial heart) have been promoted. Artificial hearts mainly use miniature mechanical pump to replace and help the blood pumping. Among them, axial blood pump with the advantages of simple structure, high efficiency, small size, easily implanted in the human body has become the development trend of artificial heart. The hemolysis maybe occurred in the blood pump by various factors. Therefore, research on the flow field analysis of axial blood pump for blood pump to clinical use has a great significance.In this paper, the flow law of the blood in the blood pump was studied. The simulation analysis on the physiology flow field in blood pump has been carried out by using CFD technology. Based on this, the structure of existing blood pump has been optimized. The specific works have been shown as follows:1. The blood flow mechanism performance in a blood pump has been studied, which belongs to the annular helical flow. The expresses of velocity, flux, pressure gradient and rheological equation are presented. The blood Standard K epsilon turbulence model equations have been derived. The movements of single blood cells in a blood pump flow have been researched, and the expression of the axial and radial velocity of blood cells has been obtained.2. The axial flow blood pump was done in vitro fluid experiment by using speed-flow-pressure experimental station. The experimental results show that:When the blood pump entrance pressure is low, there isn’t significant effect on the outlet pressure and flow; when the outlet pressure is larger, the flow rate becomes smaller in blood pump. The outlet pressure and the flow rate increases with the increase of the speed. For the liquid with large viscosity, the outlet pressure and flow rate is small. According to the human body physiology condition, the suitable entrance pressure, outlet pressure, rotating speed and flow should be selected as the boundary conditions of simulation analysis.3. By using the fluent software, the simulation analysis of the blood pump in the velocity field, pressure field, stress field and the turbulence effect was carried out, which have some influence on the mechanical damage of blood cell. The volume fraction and distribution area of the speed which is larger than the critical speed of the red blood cell impact injury have been obtained. The high shear area and the position of high turbulent kinetic energy have also been obtained.4. By analyzing the blood pumps of different pitches, different number of drainage blade and different guide vane, a better scheme to optimize the structure of the blood pump has been determined. Through CFD simulation analysis, comparison with the original blood pump, the optimized blood pump blood to mechanical injury has been reduced.