A STUDY OF A NEGATIVE IMPULSIVE WAVE GENERATOR

摘要

A compression wave discharged from the open end of a tube causes positive impulsive noise. Active noise cancellation, which is the cancelling of the noise by the addition of an inverse wave, is a useful technique for reducing impulsive noise. The main objective of this study is to present the design for a negative impulsive wave generator utilizing unsteady mass influx. In this paper, in order to clarify the relationship between the unsteady mass influx and the negative impulsive wave, numerical and aeroacoustic analyses have been carried out using an unsteady expansion wave discharged from the open end of a shock tube, together with the experimental investigations. As a result, the effect of an unsteady expansion wave on a negative impulsive wave is shown. (C) 1996 Academic Press Limited [References: 24]