Experimental Study of the Effect of High-Frequency Pulsated Gas Flow on Liquid Motion Behavior in an Oscillation Tube and the Underlying Mechanisms

This work investigated the effect of high-frequency pulsated gas flow on the liquid motion behavior within an oscillation tube and the underlying mechanisms. The results showed that the liquid exhibited periodic motion characteristics, which can be divided into three periods within a single cycle: flattening, spreading-coalescing, and constrictive splitting. Force analysis revealed that the dominant forces of each period were the gas aerodynamic force, the gas aerodynamic force/viscous force, and surface tension. Notably, the magnitude of the combined force of period 1 was several times greater than that in period 2, and several tens of times larger than that in period 3. Furthermore, the gas–liquid flow patterns were classified as stratified entrained flow and stratified flow, with the decrease and gradual downward movement of the gas aerodynamic force being the cause of flow pattern evolution. Finally, a flow pattern map was proposed, summarizing the flow patterns in the oscillation tube under different operating conditions.