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CHARACTERIZATION OF FLUID MACHINES AS ACOUSTIC MULTI-PORT SOURCES

1996; Elsevier BV; Volume: 197; Issue: 1 Linguagem: Inglês

10.1006/jsvi.1996.0514

1095-8568

Jüri Lavrentjev, Mats Åbom,

Acoustic Wave Phenomena Research

The aim of the work reported in this paper was to study the characterization of fluid machines (e.g., fans, pumps) as sources of fluid-borne sound in connected pipe or duct systems. Of special interest is the possibility of extending earlier published methods beyond the plane wave region: i.e., to include higher order modes effects. For machines which can be modelled as an acoustic multi-port source, a method which makes it possible to measure the source data is suggested together with a modal decomposition technique. In order to verify and test the measurement method and modal decomposition technique, measurements were first carried out on a small test-rig without flow, with an ordinary loudspeaker as a source. Then the method was tested on an axial fan mounted to the end of a duct. In both cases ten microphone positions, divided equally between two duct cross-sections, were used to separate the waves (five modes) into left- and right-going components. It was verified that the measured source data can be used to predict the sound field created by the fan at a given acoustic load.