Investigation of flow in a centrifugal pump
Ng, Xin Wei
Date of Issue2017
School of Mechanical and Aerospace Engineering
The blood pump that was invented nearly a century ago, has been constantly improving to change and give life to many users with heart problem. The blood pump is a Ventricular Assist Device (VAD) that has prolonged or even create a new life for patients. After several improvements, we have arrived at this stage where the blood pump is a centrifugal pump. As a gap exist in between the impeller face and the volute casing, it is necessary to determine the properties of the fluid in this leakage gap as it might result in undesirable cases such as haemolysis and thrombus formation. Done by the previous professors and students, to have a better study of the leakage gap, a dummy impeller, which has no blades, was invented so that the flow mainly focus on the leakage gap can be observed. Leakage flow analysis is done by utilizing the real and dummy impeller. For the real impeller, the mean ∆P is plotted against the operating flow rate. Whereas for the dummy impeller, the mean ∆P is plotted against the leakage flow at a reverse direction of flow. This experiment was conducted using 3 different rotational speed, 1750rpm, 2250rpm and 2500 rpm, at 4 different clearance gap, 0.2mm, 0.3mm, 0.4mm and 0.5mm. The results show that the mean ∆P decreases as the operating flow rate increases for the real impeller, and the mean ∆P increases as the leakage flow rate increases. For the pump characteristic curve plotted for the real impeller from the pump head and operating flow rate, it is observed that the characteristic curve of the blood pump test rig follows the trend of the centrifugal pump, where the pump head decreases at the operating flow increases, Experimental results taken will then be compared with the previous experimental results taken before this academic year, which tested the centrifugal blood pump at 1500rpm and 2000rpm. After comparing, it is observed that the 3 rotational speed tested is similar to the curves plotted in the previous experiments.
Final Year Project (FYP)
Nanyang Technological University