The effect of shear stress on the impeller design of centrifugal blood PUMP

Abstract

The centrifugal blood pump is mostly used in medical field. The ventricular assist devices (VADs) based on CBPs become famous modality for treatment heart failure's patients. However, The CBP has reported that cause of hemolysis and thrombosis in long term used. So, CBP factors that cause of both hemolysis and thrombosis is relating with shear stress at internal surface of CBP; High shear stress cause hemolysis and less shear stress cause thrombosis. In this study, the design of CBP has been developed in order to solve effects from high shear stress. The objective of this study is to describe the design of two types of impellers; backward impeller and Backward with under blade cut impeller. Each designed impellers are compared its effect on shear stress to determine the pro per impeller for decreasing high shear stress of blood pump. Shear stress should less than 300 Pascal in order to reduce hemolysis. Computational Fluid Dynamics (CFD) is calculated pump performance and shear stress comparing to impellers at pump speeds: 1, 1.5, 2, 2.5, 3, and 3.5 krpm. Result, the backward impeller at 2.5 krpm can produce flow rate equal to 5 liter/min and head pressure is 125 mmHg. The backward with under blade cut impeller at 3.5 krpm can produce flow rate of 5 liter/min against pressure head of 81 mmHg. All of impeller design can generate flow rate equal to 5 liter/min against of 80–125 mmHg which is the amount of body requirement. The histogram plot show that the shear stress increases when the rotational speed is increase. In this study, the backward impeller shows the lower shear stress and higher head pressure. Therefore, the backward impeller is better than backward with under blade cut impeller.