Designing a resonant panel based on Helmholtz resonators with reduced geometrical complexity

Master thesis (2023)

Authors

J. van Eijk Architecture and the Built Environment

Contributors

M. Turrin Digital Technologies - Architecture and the Built Environment (supervisor 1)
M.J. Tenpierik Environmental & Climate Design - Architecture and the Built Environment (supervisor 1)
G. Coumans Public Building and Housing Design (supervisor 2)
Faculty
Architecture and the Built Environment
Copyright: © 2023 Jordy van Eijk
Room acoustics Computer aided design Parameteric design Helmholtz resonator Computer aided manufacturing
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Published Date

16-01-2023

Language

English

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Faculty

Architecture and the Built Environment

Abstract

Acoustics combined with digital fabrication has been investigated for multiple years. Most research in this area has focused on the combination of acoustics and additive manufacturing. This is mainly due to the ability of this technique to create any geometry, which allows for very high absorption. However, it has the downside that additive manufacturing is quite expensive and the production process is time-consuming. Therefore, this study has chosen to put the geometry first and the performance of the resonators second.
To be able to produce a resonant panel based on Helmholtz resonators some additional knowledge was needed. Therefore, five experiments were performed to gain the knowledge needed to design the panel. The samples were printed using a fused filament printer and tested within an impedance tube located at the Faculty of Architecture in Delft. The experiments were concerned with:
- The position of the neck compared to the cavity: According to the results of the experiments the position of the neck has a minimal to no effect on the performance of the resonator.
- The crosstalk effect: According to the results of the experiments the effect of the crosstalk effect is minimal within the scope of this project. A small change in absorption was noticeable but so small as to be irrelevant.
- The effect of the cavity separation between two resonators: According to the results of the experiments the cavity separation can be removed without a large effect on the absorption of the resonators.
- The effect of the neck length on the width of the absorption curve: According to the results of the experiments a longer neck causes the width of the absorption curve to decrease.
- The impedance of resonators with L-shaped cavities: According to the results of the experiments an L-shaped cavity can be approximated by replacing the L-shaped cavity by a cavity with an identical horizontal section right below the orifice but altering the height, so the cavity has the same volume as the original L-shaped cavity.
After the experiments were done, a computational workflow was designed that is able to produce resonant panels based on the targeted frequency range and the possible size of the panel. The tool was theoretically verified using a case study. For the case study two panels were designed to improve the reverberation time for a room in the Faculty of Architecture. Using the Arau-Puchades method of calculating the reverberation time the panels showed to be effective at absorbing sound at low frequencies.