| Author: | Li, Wai-man |
| Title: | The performance of coupled resonators in the presence of turbulent flows |
| Degree: | M.Eng. |
| Year: | 2005 |
| Subject: | Hong Kong Polytechnic University -- Dissertations Turbulence -- Acoustic properties Air ducts -- Acoustic properties Resonators |
| Department: | Department of Building Services Engineering |
| Pages: | xii, 122, 12 leaves : ill. (some col.) ; 30 cm |
| Language: | English |
| 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. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b18100211.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 13.8 MB | Adobe PDF | View/Open |
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