Numerical investigation of the influence of different barrel lengths on the interior ballistic process within an underwater submerged launch.

The article focuses on investigating the underwater interior ballistic process and the influence of barrel length on projectile initial velocity, drag characteristics, and precursor flow field distribution using a bidirectional coupling method between classical interior ballistics (CIB) and Computational Fluid Dynamics (CFD). Numerical simulations and underwater launch experiments were conducted for five barrel lengths expressed as ratios of the water column weight to projectile weight (1.0 to 2.0), revealing that shorter barrels yield higher muzzle velocities (up to 492 m/s) with complete propellant combustion, while longer barrels increase drag and reduce velocity, sometimes causing projectile deceleration. The study also characterizes the precursor flow field at the muzzle, identifying core jet, cavitation, and dissipation regions whose dimensions and intensities vary with barrel length, with shorter barrels producing stronger cavitation effects. These findings provide insights into optimizing barrel length for underwater projectile launching, though factors like hydrostatic pressure and charge type were not considered and warrant further research.