Steady and unsteady numerical simulations were carried out to systematically research the hemodynamic performance and hemocompatibility of four groups of centrifugal blood pumps with different blade tip clearance at 173 mmHg. The gaps studied were 5.0 mm

2.0 mm

1.0 mm and 0.2 mm

respectively

the distribution of parameters and the changes of normalized index of hemolysis with the size of blade tip clearance were researched. The results showed that the origin pump had good hemocompatibility at 3.0 L/min against a pressure head of 173 mmHg; with the decrease of blade tip clearance

the max stress and the normalized index of hemolysis showed a single peak and the minimum normalized index of hemolysis 0.000 5 g/100 L was obtained in the 1.0 mm clearance structure

which reduced the risk of thrombosis in the gap between the outer impeller walls and the lower housing cavity walls; compared with the results of the unsteady simulation: steady results were often too small to predict hemolysis

the transient normalized index of hemolysis changed periodically with the impeller rotation

and the difference between its mean and the steady results was within 5%.