Numerical simulation of unsteady flow in small scale air-lift pump

Air lift pump are finding increasing use where pump reliability and low maintenance are required, where corrosive, abrasive fluids must be handled and when a compressed air is readily available as a source of renewable energy for water pumping applications. The objective of this present study is investing the performance of a small scale airlift pump, in this paper with a tube diameter ranged from 0.012m to 0.019m and a fixed length of 0.933m, by the numerical simulating results from commercial software. The simulation were performed for four submergence ratios. This paper proposed an iterative scheme for implicit time marching of density and pressure, and simulated an air-water slug flow using a VOF model. The results showed that the pump capacity and efficiency are functions of the air mass flow rate, submergence ratio, and riser pipe length. The highest water and air mess flux ratio was found out in each tube at different submergence ratio. The best efficiency range of the air-lift pumps operation was found to be in the slug and slug-churn flow regimes. The simulation result is in a good agreement with the experimental results. More characteristics, like bubble shape, bubble velocity, pressure drop and velocity profile in the flow region were investigated by the numerical analysis.