Experimental characterization of acoustic multi-ports
Number of Authors: 4
2014 (English)In: Forum Acusticum paper, European Acoustics Association (EAA), 2014Conference paper (Refereed)
The generation and scattering behaviour of fluid machines in duct or pipe systems is of great interest to minimize disturbing and harmful sound emission, for instance of air condition systems. In general an in-duct element, e.g., fan, diaphragm, and bend can both generate sound, referred to as the active properties, and scatter sound which is referred to as the passive properties. One approach to describe the sound field created by a fluid machine or in duct components is to apply a linear multi-port model that includes direction-depending transmission and reflection coefficients for the wave-modes and the sound generation. The model parameters can be ascertained either experimentally or numerically.In a first step, a number of external sound fields dominating the existing sound field are applied, in order to determine the system scattering. As the second step, the reflection-free source strength can be computed using the data from the first step. Once the multi-port data are determined, the sound field within the duct can be calculated for arbitrary acoustic loads. This paper discusses an approach to measure the multi-port data in ducts with flow. The method is applied to study a sharp edged orifice as an component for an aircraft climate system with 8 acoustic modes incident on both sides which leads to acoustic multi-ports of the order 16. To perform the measurements loudspeaker and microphone arrays containing 24 sources and 32 microphones were optimized to create well-conditioned matrices to minimize the errors in the resulting multi-port data. The power balance is then applied on the resulting scattering data to evaluate the dissipation of energy from the acoustic field into the vorticity field.
Place, publisher, year, edition, pages
European Acoustics Association (EAA), 2014.
mulit-port, forum acusticum, acoustic, air-conditioner, orficie
Research subject Vehicle and Maritime Engineering
IdentifiersURN: urn:nbn:se:kth:diva-160821ScopusID: 2-s2.0-84953336862OAI: oai:DiVA.org:kth-160821DiVA: diva2:791259
Forum Acusticum 2014, 7-12 September 2014, Krakow, Poland
FunderEU, FP7, Seventh Framework Programme
QC 201603142015-02-272015-02-272016-03-14Bibliographically approved