Measurement system for leakage flow in centrifugal blood pump

• Main Author: Tan, Ying Hao.
• Other Authors: Wong Yew Wah
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/54018
• Institution: Nanyang Technological University

Using ANSYS FLUENT v 14.0, a computation fluid dynamics simulation was carried out to analyze the effect of gap size on the flow in a centrifugal blood pump. The modelling process was conducted using GAMBIT, a design software. For investigation purposes, 4 models with different clearance gap sizes, namely 0.2mm, 0.3mm, 0.4mm and 0.5mm. The boundary conditions of the simulation include a 2000 rotations per minute (rpm) impeller speed and inlet flow rate from 1 litre per minute to 7 litres per minute. Using the simulation results based on boundary conditions, the leakage flow, pressure and velocity distribution were analyzed. The simulations has shown a general trend in the pump performance, leakage flow, and pressure and velocity distribution for all the pumps of varying gap sizes. The results show an inverse relationship between the pump performance and gap size, i.e. the pump head decreases with increasing gap size. On the other hand, an increase in flow rate would result in a decrease in pressure head and a gradual increase in pressure from the impeller to the throat of the pump. There is a greater leakage flow at the front gap than the rear gap, due to the higher pressure at the front. The lower pressure and leakage flow at the rear gap could be explained by the washout holes at the rear. The results also indicate a positive correlation between the leakage flow and gap size. The larger the gap size, the greater the leakage flow, and hence, the greater the volumetric efficiency. This set of simulation results using FLUENT v. 14.0 are compared to previous experimental studies and simulation using CFX 11.0 and FLUENT v. 13.0. It can be noted that the results from the different experimental studies display similar trend. The results from FLUENT v. 14.0 are more closely correlated to the previous results from FLUENT v. 13.0, indicating the consistency of the FLUENT program.