The numerical investigation and experimental results of the proto-pump LAP-00 show that at design rotational speed of 9000 r/min

the flow rate corresponding to the highest efficiency point is 11 L/min

which is much higher than clinical use(38 L/min)

causing the pump to work at off design point in clinic use with a low efficiency.Besides

in the diffuser region

flow separation and recirculation may cause blood stagnation and thrombosis.The improved design for pump LAP-23 decreases the design rotational speed from 9000 r/min to 8000 r/min

thus reduces the high shear stress on blood cells at impeller tip;meanwhile

it decreases the design flow rate to 6 L/min and eliminates flow separation and recirculation in the diffuser region.