Performance Analysis of a Microbubble Pump with Novel 'S-Shape' Impeller by Experimental and Numerical Analysis at Design and Off-Design Operating Conditions

A microbubble pump with a novel 'S-shape' impeller is introduced to evaluate pump performance under design and off-design conditions. The robustly designed 'S-shape' impeller has a continuously connected impeller blade, which improves the structural strength of the impeller blades as well as pump performance. Pump performance is evaluated by experimental measurements and numerical simulations at three different flow conditions. An experimental apparatus for measuring pump performance is fabricated, and pressure, flowrate, and pump torque are measured in real-time at each flow condition, and the measured data are saved using a data logging system. In order to analyze the reliability of the measured data, evaluations of uncertainty and errors are performed for each of the flow conditions. A commercial code, ANSYS CFX, is introduced to analyze the flow field inside the pump impeller and the pump performance. Throughout the microbubble pump's performance analysis under design and off-design conditions, turbulent kinetic energy has a higher value as the flowrate is relatively small compared to the design flow condition. It is noted that violent mixing between the internal flow inside the impeller and the channel flow increases turbulent kinetic energy. The higher turbulent kinetic energy observed in the lower-flow condition corresponds to the higher relative uncertainty. In the design flow condition, the highest magnitudes of the recirculating flow are observed as compared to the other two flow conditions. The highest recirculating flow observed at the design flow condition helps to achieve a better momentum exchange, thus increasing the overall efficiency of pump.