Numerical analysis of flow caused by emission of compression wave from open end of circular tube

When a compression wave propagating in a straight circular tube reaches the tube's open end, reflection and radiation of the compression wave occur. The reflected compression wave propagates in the circular tube toward its portal as an expansion wave, and the emitted compression wave extends into the surrounding area from the open end as an impulsive wave. During the process of reflection and radiation, the flow at the open end is very complex due to three-dimensional phenomena. The purpose of this paper is to investigate the mechanism of generating the impulsive wave from the compression wave. A numerical analysis is carried out for the emission of a propagating compression wave from an open end of a circular tube with an infinite baffle plate at the open end, using the TVD method. The process of generating the impulsive wave and the influence of compression wave length on its generation process are discussed, and the directivity of the impulsive wave at near field is shown.