Submerged gas jet is commonly encountered in underwater cutting, underwater jet-propulsion, liquid metal mixing and other applications. In this paper the transient dynamics for the high-speed submerged gas jet in a flowing water environment was investigated. The experiments were carried out in an open water tunnel which could achieve high degassing rate. The jetting flow rate was varied from subsonic to sonic state to obtain different flow patterns. A compressible multiphase model using the coupled Level Set with Volume of Fluid (VOF) model was adopted to investigate on the detail flow structure. Three flow patterns including the transparent cavity mode, the cavity-jetting mode and the periodic jetting mode were observed. The predicted gas–liquid interface profiles, as well as the unstable shedding process agreed well with the experimental data. The evolution of the internal vortex structures and the pressure distributions were analyzed in detail, obtaining the transition mechanism between different modes. The main flow characteristics including the cavity length, the penetration length and the shedding frequency were obtained for different cases. It was found out that with the increase of the jetting flow rate, a local smallest penetration length existed at the cavity-jetting mode. The Strouhal number relating to the shedding frequency firstly descends dramatically and then kept in the level of 10⁻³ at the periodic jetting mode

水下切割，水下喷射推进，液态金属混合和其他应用中通常会遇到浸没式气体喷射。本文研究了流动水环境中高速水下气体射流的瞬态动力学。实验在可以实现高脱气率的开放水道中进行。喷射流速从亚音速状态变化到音速状态，以获得不同的流动模式。采用了一种将液位与液位耦合的可压缩多相模型（VOF），以研究其详细的流动结构。观察到三种流动模式，包括透明腔模式，腔喷射模式和周期性喷射模式。预测的气液界面曲线以及不稳定的脱落过程与实验数据吻合良好。详细分析了内部涡旋结构的演化和压力分布，获得了不同模式之间的过渡机制。获得了不同情况下的主要流动特性，包括腔长，穿透长度和脱落频率。发现随着喷射流量的增加，在腔喷射模式下存在局部最小的穿透长度。与脱落频率有关的斯特劳哈尔数首先急剧下降，然后保持在10水平 获得了不同情况下的穿透长度和脱落频率。发现随着喷射流量的增加，在腔喷射模式下存在局部最小的穿透长度。与脱落频率有关的斯特劳哈尔数首先急剧下降，然后保持在10水平 获得了不同情况下的穿透长度和脱落频率。发现随着喷射流量的增加，在腔喷射模式下存在局部最小的穿透长度。与脱落频率有关的斯特劳哈尔数首先急剧下降，然后保持在10水平^-3在定期喷射模式下