Development of the Multistage Centrifugal Blood Pump for the Extended Use of Rotary Blood Pumps

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The present study deals with the development of a novel centrifugal pump which consists of the multistage impeller. The use of a multistage impeller leads to generation of high pressure without increasing the rotational speed of the motor. The direct advantage of this structure will be the decreased amount of the blood cell destruction(blood trauma) in the device.The first prototype was designed for the virtual working condition of the flow rate of 3.0 L/min and the pressure difference of 500 mmHg. The prototype employs the following design features to ensure generation of high pressure.1. the suction volute in the inlet passage2. the impeller profile for high pressure3. the double volute to minimize the radial thrust on the impellerThe first prototype demonstrated the sufficient pump performance. The CFD analysis of the internal flow field of the device has revealed the need for design improvement in terms of the blood cell destruction and thrombus formation in the device.1 addition of the front shroud to the impeller2 use of the wider gap in the tongue of the double volute casing3 use of the shrouded return vaneThe second prototype with the above improvements demonstrated a bit lower hydraulic performance due to the increase in the internal leakage flow associated with the design change to enhance the wash-out condition of the device. However, we succeeded in decreasing the maximum shear stress over the lethal value for blood cell destruction and in elimination of the stagnant area which possibly leads to the thrombus formation.