Characteristics of Flow Fluctuation in Natural Circulation Air-Lift Pump : 1st Report, Relation between Characteristics of Flow Fluctuation and Flow Rate of Circulating Water

抄録

An experimental investigation was made on the pumping characteristics of an air lift system consisting of an air-water separator and a constant head tank which are connected by a 25.9 mm I.D. U-tube and a water-return tube. This type of natural circulation system presents a signifacant fluctuation of flow; especially in some flow conditions with reduced pressure, there occurs a self-excited flow oscillation. This is attributed to the compressibility of gas in a gas-liquid two-phase mixture and reversion of water flow from the two-phase mixing section to the head tank. Time-averaged flow rate of water increases with the intensity of flow oscillation. The gas flow rate corresponding to the initiation of lifting water is reduced due to the flow oscillation.