MEDIDA DE LA IMPEDANCIA ACÚSTICA EN CONDUCTOS Y SILENCIADORES BAJO CONDICIONES DE BORDE DIFERENTES

Abstract

This research presents details of a measurement system used to determine acoustical parameters for duct systems. In particular, the normal incidence reflection factor and the acoustic impedance were obtained theoretically and experimentally. The effect on the resulting parameters of factors such as air flow and duct curvature was investigated. It was found that the flow induced effect was equivalent to shortening the length of the duct carrying the flow. An empirical expression that predicts the equivalent length of the duct in terms of the flow Mach number is suggested. On the other hand, it was found that the acoustic input impedance of a curved duct is equal to the same parameter for a straight duct of length equal to the central axis of the curved duct.