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Department:Department of Building Services Engineeringen_US
Author:Li, Wai-manen_US
URI:https://theses.lib.polyu.edu.hk/handle/200/4473-
Language:Englishen_US
Title:The performance of coupled resonators in the presence of turbulent flowsen_US
Abstract:Helmholtz resonators are used to attenuate the unwanted sound in a variety of applications. This dissertation presents the findings on coupled resonators in the presence of turbulent flows. The sound attenuation of coupled resonators installed along a rectangular duct was studied experimentally at five air flow velocities: 0 m/s, 3 m/s, 5 m/s, 7 m/s, 9 m/s. Experiments demonstrate that the coupled resonators are tested under high turbulence intensities. Experiments confirm that the transmission loss of the coupled resonators generally drops with a higher velocity. The coupled resonators can perform effective sound attenuation for an air flow below 9 m/s. Negative troughs occur at the resonance frequency when the air flow velocity exceeds a certain value. The resonance frequencies of the resonators remain unchanged in the air flow conditions. The experimental results reveal that there is interaction between coupled resonators under different air flows. And the attenuation frequency bandwidth is widened by tuning the neck width of the resonators close to each other under both no flow and flow conditions.en_US
Pages:xii, 122, 12 leaves : ill. (some col.) ; 30 cmen_US
Year:2005-
Degree:All Masteren_US
Degree:M.Eng.en_US
Subject:Hong Kong Polytechnic University -- Dissertationsen_US
Subject:Turbulence -- Acoustic propertiesen_US
Subject:Air ducts -- Acoustic propertiesen_US
Subject:Resonatorsen_US
Access:restricted access-

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