Optimization of a passively suspended injection impeller for Left ventricular assist device.

BACKGROUND: A rotary blood pump with a passively levitated impeller and a large bearing gap between housing and impeller in the range of 0.6 mm has been developed for Left ventricular assist device (LVAD).

OBJECTIVE: The purpose of the present study is to determine the optimal injection angle of the impeller to improve its radial stability by increasing the radial suspension force.

MTEHODS: Since the radial and axial suspension forces generated by an injection channel were equal, the axial suspension force obtained from numerical simulation was chosen as the evaluation parameter. First, the impellers with different injection angles were calculated with numerical simulation to obtain the maximum axial suspension force. Second, the radial motion of the impeller was experimentally measured for the evaluation of the radial stability.

RESULTS: The numerical analysis revealed that the axial suspension force acting on the impeller reached the maximum value at the injection angle of 60 degrees. In the measurement test, the impeller with injection angle of 60 degrees achieved the most stable radial movement. Therefore, the effectiveness of the numerical analysis was validated.

CONCLUSIONS: The injection angle of impeller could be optimized to improve its radial stability, and the optimal injection angle was 60 degrees.