Pressure behaviour in riser tube of a short airlift pump

The pressure behaviour in riser tubes of a short airlift pump was investigated for various submergence ratios, air discharges and riser tube lengths. Two high-frequency response pressure transducers were placed at various positions along the riser tube. The analysis of the recorded pressure signals gave the mean local pressure at specified vertical positions for various submergence ratios, air discharges and riser tube lengths. The experimental data show a non-linear pressure behaviour near the exit of the air ejector due to the increased friction losses in this region. The pressure behaviour for increasing air discharge at a position along the riser tube is related to the corresponding two-phase flow pattern in the riser tube. The pressure distributions along the riser tube for various submergence ratios were compared with the predictions of the Stenning-Martin model.