Flow investigation in a centrifugal pump

• Main Author: Lee, Wai Wai.
• Other Authors: Chan Weng Kong
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Mechanical engineering::Fluid mechanics
• Online Access: http://hdl.handle.net/10356/40538
• Institution: Nanyang Technological University

The increase in the number of people suffering from the cardiovascular diseases leads to the demand of ventricular assist devices. Centrifugal blood pumps had emerged as one of the better VADs which aid the failing heart. However, hemolysis and thrombus formation posed a major problem for this VAD. Investigation of the leakage flow will help to understand the possibility of thrombus formation and hemolysis by providing important and reliable information to develop a better design for the pump. A computational fluid dynamics analysis of a centrifugal blood pump model using ANSYS CFX 12.0 was conducted in this study. There are four different parallel gaps that are employed in the analysis. They are 0.2mm, 0.3mm, 0.4mm and 0.5mm and each gap running at an impeller rotation speed of 1500rpm, 2000rpm and 2500rpm. Operating flow rates ranging from 0.75 litres per minute to 8.75 litres per minute. Based on the study on the leakage flow characteristics, the leakage flow was found to be dependent on several factors. These factors include throttling, gap heights, rotation speeds and the pressure difference within the leakage gaps. Leakage flow rate was observed to increase with increasing gap heights, rotation speeds and the pressure difference. The front leakage flow rate was also found to be higher than the rear leakage flow rate due to the presence of washout holes. Comparison was also done between the CFD results with experimental results. The comparison also proved that both CFD and experimental results produce the same trend where the largest gap heights will have the highest amount of leakage flow rate.