Development of a centrifugal pump with thick blades

We have developed a centrifugal blood pump with thick impeller blades (60% of pitch) to obtain a small tip clearance. An unshrouded impeller with 6 backward curved thick blades was used to reduce the dead zone between the shroud and upper casing. A streamline angle in volute was uniform in circumferential direction by continuity and angular momentum conservation. To prove the effectiveness of small tip clearance, performance and hemolysis tests were conducted on pumps with a tip clearance of 0.5, 1.5, and 2.0 mm at exit with the blade thickness of 60% of pitch, and with that of 1.0, 2.0, and 2.5 mm at exit with the thickness of 40% of pitch. The results showed that the smaller the tip clearance, the better the hydrodynamic and hemolytic performance. The best result was seen in the pump with tip clearance of 0.5 mm with a blade thickness of 60% of pitch. These results suggest that a centrifugal pump with thick blades and a small tip clearance can be a promising alternative as a cardiopulmonary bypass pump.