Abstract This study employs a CFD approach using Fluent to establish a 2D axisymmetric airlift pump model. The Eulerian multiphase model and SST k-ω turbulence model are used to simulate three air injection modes: continuous, stepped and sinusoidal. Model validation was performed against experimental data. The effects of oscillation frequency (0–2 Hz) on gas holdup, liquid flow rate, efficiency, and hydraulic characteristics were systematically analyzed. Results show: (1) Oscillatory air injection significantly enhances pump performance. Sinusoidal injection at 1 Hz achieves a peak mass transport efficiency of 84%, a 34% improvement over continuous injection. (2) Stepped injection creates periodic large bubble clusters that strengthen local driving force but incur higher turbulent dissipation. Sinusoidal injection promotes uniform small bubbles and more stable liquid transport. (3) Vortex analysis indicates that stepped injection generates concentrated intense vortices in the riser mid-section, leading to uneven energy dissipation. Sinusoidal injection enhances gas-liquid mixing stability and reduces overall flow energy consumption. This work overcomes the conventional focus on continuous injection, elucidating the mechanism linking oscillation frequency and flow regime evolution. This work overcomes the conventional focus on continuous injection. It elucidates the underlying mechanisms connecting oscillation frequency and flow regime transition, establishing a theoretical foundation for optimizing airlift pump performance through gas-liquid interaction mechanisms. Furthermore, it provides critical parametric guidance for implementing oscillatory injection technology in engineering practice. The study holds significant value for both academic innovation and practical application in the design of gas-liquid transport systems for marine resource exploitation and related fields.
Li et al. (Thu,) studied this question.