Fluid Dynamic Studies for Performance of Centrifugal Blood Pump with Magnetically Suspended Impeller

与位移式心室型人工心脏相比，离心血泵简单、紧凑、易于操作、价格便宜。它有望成为下一代的人工心脏。目前，市售的离心血泵有一些缺点；轴承和密封产生的剪切应力和摩擦热导致血液退化。因此这些泵在临床上是短期使用的。为了克服这些缺点，作者一直在开发一种带有磁悬浮叶轮的离心血泵。(1)为了提高泵的效率，我们研究了多种叶轮叶片和扩散器的泵性能，以及叶轮盘和泵壳之间间隙的流量。我们可以找到两种高效率的叶片。一种是出口角β =90的16片叶片，另一种是出口角β =40的7片叶片。这些泵的溶血比Bio-Pump小。需要进一步调查以确定哪种类型更好。(2)良好的洗出流是通过可视化观察叶轮盘与泵壳之间的间隙。然而，动物实验表明，白色的血栓附着在叶轮盘的聚碳酸酯表面。但这一问题可以通过表面抛光和硅涂层来解决。(3)泵在恒定电机电流下的运行表现出类似斯特林定律的压力-流量特性。因此，今后推荐采用恒流模式。(4)对各种孔口的血液回路进行溶血试验，结果表明，有锐角的孔口朝上游时溶血严重。剪切应力的数值分析证实了这一事实。总之，这种泵被证明是很有希望作为长期使用的血泵。

Centrifugal blood pumps are simple, compact, easy to handle, and cheap compared with the displacement ventricular type of artificial hearts. It is promised as an artificial heart of next generation. At present, commercially available centrifugal blood pumps have some drawbacks ; the shear stress and friction heat produced on bearing and seal cause degeneration of blood. Therefore these pumps are clinically used for short term. To overcome these drawbacks, the authors have been developing a centrifugal blood pump with magnetically suspended impeller.(1) To improve pump efficiency, we have investigated the pump performances of many kinds of impeller's blades and diffusers, and the flow in the gap between the impeller's disc and the pump housing. We could find two kinds of blades with high efficiency. One is the 16-blades with outlet angle beta=90ﾟ and the other 7-blades with beta=40ﾟ. The hemolysis of these pumps is less than that of Bio-Pump. Further investigation will be necessary to determine which type is better.(2) Good washout flow is the gap between the impeller disc and the pump casing is observed by visualization. However, animal cxperiments show that white thrombus adheres to the polycarbonate surface of the impeller disc. But this problem is solved by surface polishing and coating with silicon.(3) The pump operation under the constant motor current shows the pressure-flow characteristics similar to Stirling's law. So the constant current mode is recommended hereafter.(4) Hemolysis test in the blood circuits with various kinds of orifices proves that the severe hemolysis is observed in case of the orifice with sharp corner faced upstream. This fact is verified by numerical analysis of shear stress.In conclusion, this pump proves to be very promising as blood pump for long-term use.