Generation and scattering of acoustic modes in ducts with flow

摘要

The generation and scattering behaviour of fluid machines such as pumps or fans in connected duct or pipe systems is of great interest to minimize disturbing and harmful sound emission, for instance of air conditioning systems. One approach to describe the sound-field created by a fluid machine or in a duct component is to apply a linear multi-port model that includes direction-depending transmission and reflection coefficients for the present wave-modes and the sound generation. Once this characteristic data are determined, the sound-field can be calculated for arbitrary acoustic loads. This paper describes an approach to measure the scattering of the first 8 modes in a duct system with flow, using external loudspeakers as sound sources.