Numerical Computation of the Impulsive Sound Generated by a Projectile Discharging from a Muzzle

Abstract [338] The goal of this paper is to suggest the numerical method for the simulation of impulsive sound generation and to investigate the acoustic field produced by a projectile discharging from a muzzle. For this problem, a direct simulation using the conventional flow computation method is performed to obtain the acoustic source information in near-field. Computed unsteady flow results are used to obtain the solutions in far-field. Hybrid method using the flow results computed in near-field boundary region combined with an integral formulation to evaluate the radiated noise in far-field is suggested. First, a numerical study on wave dynamic procedure occurring in muzzle flows, which are made by a supersonic projectile released from the open end of a tube into ambient air condition, is implemented. From numerical simulation in near-field, such complex phenomena, including blast waves, jet flows, shock waves and their interactions in the muzzle blast, are described. Second, the Euler equations assuming axi-symmetric flows, which are able to ensure the non-linear effects while propagating outward and to simulate the near/far-field acoustic propagation, are applied for impulsive sound propagation resulting from complex muzzle blast through the unsteady flow results computed above. This numerical method is efficient and powerful computation tool to extend impulsive sound prediction near-field to the very far-field.