Abstract
In order to design a centrifugal blood pump with less hemolytic and antithrombogenic properties, secondary flow inside the pump, such as vortex and recirculation, must be properly controlled. The flow visualization was conducted to investigate flow patterns in centrifugal blood pump. The visualization methods used were an oil film method and a tracer method. In the tracer method, movement of tracers were recorded by a high speed video camera which can take 3000 frames per second. The correlation between the visualized flow patterns and results of in vitro hemolysis tests was also investigated. Inadequate vane angles caused separations of streamlines, vortex formation, and sudden change in flow direction. Hemolysis increased under existence of such irregular flow patterns. Flow visualization experiments demonstrated that secondary washout vanes attached on the back side of the impeller can generate flow going from the center to the outer portion of impeller's backside and another flow in opposite direction at the same time. It may enhance washout effect at the backside of the impeller leading to less thrombogenic property
