A circulatory assist pump, which can be used for around two weeks after an operation, is under development by AIST. For R&D of a centrifugal blood pump, it is important to prevent the hemolysis, which is caused by high shear rate. Since the back gap of the impeller and the volute are the typical high shear regions, flow visualization analysis was conducted to investigate the shear rate distribution. Judging from the shear rate at impeller back space and on the volute surface, it was found that the shear rates were far below the hemolysis level. The results of the flow visualization well explained the hemolysis test results, where the hemolysis level was found to be 40% of a commercial centrifugal pump. So it was proved that this centrifugal blood pump had good fluid dynamic characteristics to prevent hemolysis.
