WHIRLING MOTION OF THE IMPELLER OF A CENTRIFUGAL PUMP AS A VENTRICULAR ASSIST DEVICE

摘要

Compact centrifugal pumps have recently been used as left ventricular assist devices (LVADs). Non-contact bearing systems are usually employed for these pumps to avoid blood coagulation at the stagnant regions inside the pump. These bearing systems do not have such sufficient rigidity that the standard operational conditions usually exceed their critical speeds. There are possibilities when the whirling motion of the impeller causes instability of the impeller suspension system. In this study, we conducted measurements of the radial displacement of the impeller of the centrifugal pump to investigate the effect of the whirling motion of the impeller on the stability of the impeller positions. The results indicated that the system fell into an unstable status when the ratio of the whirling motion to the rotational speed of the impeller reached 0.5.