Study on draining off water mechanism and interaction characteristic of high-temperature and high-pressure combustion-gas jets with the water

Highlights: • A new method of underwater launching on draining off water in real-time is proposed. • We open pores around the circumference of the warhead to form a dry path without complex devices. • Complex interaction of high-pressure combustion-gas jets and water is studied. • Expansion process of combustion-gas jets in the confining tube is analyzed by experiments. • The flowfield structure and parameter distribution is obtained by numerical simulation. A new method of underwater launching is proposed to overcome the water resistance in the barrel and realize continuous launching by forming gas curtain without any complex device. Namely, part of gunpowder combustion-gases behind the projectile is guided to the space in front of underwater projectile by opening pores around the circumference of the warhead, to form a dry launching path. Based on this, the expansion process of combustion-gas jets in the confining tube filled with water, especially complex interaction of high-pressure and high-temperature combustion-gas jets and water is studied by experiments and numerical calculations. The results show that, when the high-velocity combustion-gases inject into motionless liquid environment, multiple Taylor cavities are formed and typical structure of Taylor cavity presents two parts, including bubble head and combustion-gas path. The distribution of the recirculation zone is an important factor for the flow field structure and the effect of draining off water. The recirculation zone of the central jet expands downstream with time going on and is decreasing until it disappears. While, the recirculation zone of lateral jet is strengthening with developing downstream. In the whole expansion process, lateral combustion-gas jet plays a significant role on radial expansion process of Taylor cavities.