Numerical Analysis of Muzzle Flow Field Characteristics of Underwater Gun Using Gas Curtain Launch
A two-dimensional unsteady numerical model for the muzzle two-phase flow field is established to study the muzzle flow field characteristics of underwater gun using gas curtain launch.The accuracy of the numerical model is verified,and the initial jet flow field and gunpowder gas jet flow field at the muzzle of 30 mm smoothbore gun using gas curtain launch are simulated.The numerically simulated results indicate that the gas curtain in front of the projectile expands out of the muzzle to form an initial jet under the propulsion of projectile,and two oblique incident shock waves generated by initial jet near the muzzle normally reflect at the central axis.As the ambient pressure within the gas curtain decays,two incident shock waves undergo Mach reflection at the central axis,resulting in the formation of a bottle-shaped shock wave structure then.The displacement of Mach disk of initial jet remains relatively constant,but it's diameter linearly increases over time.Once the tail of projectile exits the muzzle,the gunpowder gas rapidly expands towards the front of projectile side,engulfing the Mach disk of initial jet.The incident shock waves of gunpowder gas jet undergo Mach reflection on the bottom wall of projectile at 210 μs,followed by Mach reflection occurring twice near the central axis,leading to the formation of a bottle-shaped shock wave structure with double three-wave points.The displacement of Mach disk in the gunpowder gas jet demonstrates an exponential attenuation pattern over time,while the diameter exhibits a trend of"growth-sudden increase-stability".
underwater launchmuzzle flow fieldshock reflectionbottle-shaped shock waveMach disk
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