Research on gas–liquid two-phase flow characteristics of compressed air blowing water

The process of compressed air being blown into a body of water generates a complex gas–liquid two-phase flow field. This paper describes numerical simulations of compressed air blowing water using the volume-of-fluid multiphase flow method. The accuracy and convergence of the numerical method are verified by comparison with experimental data and high-speed imaging results. Based on a visualized symmetric water tank blowing system, the gas–liquid two-phase flow characteristics inside the tank are analyzed. In the initial stage of the blowing process, the gas jet flow at the center is minimally affected by the gas–liquid mixing induced by the initial momentum of the compressed air. Subsequently, the gas jet mixes with the surrounding liquid water, forming an elliptical gas–liquid mixture in the middle of the tank. As the jet develops, it evolves into a turbulent mixing region influenced by the buoyancy of the surrounding environment. Under the effect of gas turbulence and buoyancy, a cavity structure forms inside the tank, causing the gas–liquid interface to separate. The liquid level rapidly drops as gas accumulates in the tank, and the water is eventually expelled. A visualized ballast tank blowing system is designed, and the gas–liquid two-phase flow patterns inside the tank are discussed. The variations in internal pressure and the free liquid surface are determined, and the air supply and drainage mechanisms of the water tank, along with their influencing factors, are clarified. The results verify the correctness of the numerical model.