Pseudo-Random Pressure Pulses Used to Determine the Shape of Reflected Waves from an Opening

This work forms part of a study into reflection behaviour within a duct directed towards the understanding of the problems associated with metering pulsating gas flows. A novel application of correlation analysis is used to predict the shape of the reflected wave from an opening of finite thickness. The incident wave is in the form of a pseudo-random binary sequence pressure pulse sequence which enables incident and reflected waves to be distinguished one from the other. It is shown that for waves of small amplitude, reflections do not occur in like shape to that of the incident wave. These shapes are influenced by both the amplitude of the incident wave and the geometry of the opening. It is believed that this technique makes an original contribution to the study of reflection behaviour and the use of correlation analysis.