中文摘要：

引言 气升式外环流反应器具有结构简单、无机械传动部件、造价及能耗低、容易实现工业放大等优点，并且可以通过加入构件实现对流动、传质和传热效率进行控制和强化，目前已广泛应用于化学工程、环境工程和生化工程等领域。对于此类反应器，其内部的气含率、气泡大小和分布以及运动状况是影响气液传质、传热及化学反应的关键因素，因此研究这些流体力学参数的空间分布和变化规律对于反应器设计和性能预测具有重要的理论意义和工程价值。

英文摘要：

The axial and radial profiles of the gas holdup and bubble parameters in an external-loop airlift reactor of inner diameter 0.09 m and height 1.8 m were measured with the differential pressure method and dual-tip electrical conductivity probe at different superficial gas velocities. Air and water were used as the gas and liquid phases, respectively. The experimental data of the average and local gas holdups, bubble size and its distribution, bubble rising velocity, bubble frequency and gas-liquid interfacial area were obtained, and were analyzed based on the gas-liquid flow field and bubble-bubble interaction. The local gas holdup was correlated in terms of superficial gas velocity, axial height and radial position based on the experimental data.