Computational Fluid Dynamics Analysis of Hydrodynamic Bearing Clearances on Hemolysis in a Centrifugal Blood Pump

Blood pump has been as a kind of auxiliary device to be chosen for heart disease or congestive heart failure patients. This requires the device has good blood compatibility for long-term reliability. However, blood clotting and hemolysis are usually be found on flow path, the complex flow patterns within the hydrodynamic bearing clearance between the rotor and the stationary shaft have a dramatic effect on both the hemolysis and thrombosis. Detailed computational fluid dynamics (CFD) analyses were performed in this study to investigate such flow behavior in hydrodynamic bearing clearance region for a centrifugal blood pump. The rotor is completely levitated by hydrodynamic force and driven by a brushless DC motor. The flow conditions were analyzed under a flow rate of 2-7 L/min against a head pressure of 80-120mmHg, and the speed of rotor is 3000 rpm. Effects of groove number, spiral angle and groove width on blood damage of the spiral groove bearings (SGB) are investigated by orthogonal experiment design. The experimental results show that groove number is the most remarkable factor to the hemolysis. The variation tendency of hemolysis reveals that the best combination of geometry is the one with groove number of 8, spiral angle 15 degrees and groove width 3/1.4.