A numerical study on the generation of impulsive noise by complex flows discharging from a muzzle

摘要

A numerical study Oil impulsive noise generation produced by complex flows discharging from a muzzle is achieved and the basic structures generating impulsive noise are analyzed. Complex flow features by a muzzle flow and noise generation mechanisms by several sources of noise are discussed front numerical simulations. Two-dimensional axisymmetric Euler equations are used for governing equations. High-order dispersion relation preserving finite difference method and an optimized four-level marching method are used for spatial discretization and time integration, respectively. In order to show the capability of this method to capture blast waves and to examine the basic generation mechanism of acoustic waves from a muzzle, the interaction between a shock/blast wave and a vortex ring is implemented. From the numerical simulation of the 7.62-mm NATO rifle G3 with a DM-41 round in the near field, complex blast waves, jet flow, various vortices and their interaction phenomena are described and noise generation mechanism due to the interaction of complex flow structures is observed. The present results demonstrate that numerical simulation using computational aeroacoustic methods provides not only a reliable way to determine the blast wave dynamics of the muzzle flow but also allows an Opportunity to study the physics and detailed mechanisms of the noise generation and propagation due to the interaction of complex flow structures generated from a muzzle system. Copyright (C) 2008 John Wiley & Sons, Ltd.