Discharge of a shock wave from an open end of a tube

Abstract

When a pressure wave propagates along a constant area straight tube and reaches at the open end, an impulsive wave is emitted outward from the tube exit toward the surrounding area and causes an impulsive noise like a sonic boom. In order to clarify the magnitude of an impulsive wave obtained by the discharge of a weak shock wave from an open end of a tube in relation to the noise problem and the industrial devices, the experimental and numerical investigations have been carried out for various strength of a shock wave. A simple open end shock tube with the flange at the tube exit was used and the numerical calculation using the TVD scheme was performed. The effective equations which concerns with the magnitude of an impulsive wave generated by the emission of a shock wave have been obtained from the procedure of the open end correction based on the aeroacoustic theory and the numerical results. The influence of open end correction length and the diameter of a flange on the magnitude of an impulsive wave has been discussed.