Acoustic absorber design (1999)
Type of ContentTheses / Dissertations
Thesis DisciplineMechanical Engineering
Degree NameMaster of Engineering
PublisherUniversity of Canterbury. Mechanical Engineering
The aim of the Acoustic Absorber Project was to investigate the performance of a range of materials as acoustic absorbers. A literature search on acoustic absorbers was carried out first and is presented with a summary of commercially available absorbers in the Absorber Survey. Modifications were made to the Reverberation Room in the Department of Mechanical Engineering, University of Canterbury. Tests showed that the Room modifications and diffuser installation improved its sound field diffusivity and uniformity, ensuring reliable absorption measurements. Apparatus was then built and used to measure the flow resistance of porous materials. This equipment was pivotal to the successful specification of materials used as acoustic absorbers. More than fifty different absorbers were tested in the refurbished Reverberation Room to determine their absorption coefficients. Subsequent analysis was carried out to compare the different materials, thicknesses and systems used as absorbers. Various models were used and developed to predict the measured results. The models produced similar trends to the measured data but with lower absorption coefficients. It was found that tuned absorbers could be produced from CMSG foam with impervious films, giving high absorption in selected frequencies. Wideband absorbers could be made at low cost from low density foam, polyester or fibreglass with fabric coverings, each optimised for flow resistance. Contoured foams were also found to be very effective wideband absorbers. Optimal acoustic absorbers can now be designed and produced to satisfy different absorption requirements.
RightsCopyright Jerome P Parkinson
Showing items related by title, author, creator and subject.
Pettersson, Matthew J (University of Canterbury. Mechanical Engineering, 2002)The in-duct attenuation performance, or insertion loss, of a range of absorbers was measured, and guidelines for the design and application of absorbers in air ducts were developed from the measured data. A test facility ...
Whitehead, Timothy David (University of Canterbury. Mechanical Engineering, 2005)The purpose of this project was to investigate the acoustic performance of a range of resonant absorbers as typically used in automotive applications. A literature review considering sources of exhaust noise, muffler types ...
Han L; Li J; Gu X; Ma B; Wang N; ZHAO, DAN (Elsevier BV, 2021)The baffle is a practical and promising passive damping method of dissipating acoustic energy and increasing acoustic losses in a solid rocket motor (SRM). In this study, numerical studies were conducted conjunction with ...