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Otaru, Abdulrazak Jinadu (2018) Fluid flow and acoustic absorption in porous metallic structures using numerical simulation and experimentation. PhD thesis, University of Nottingham, United Kingdom.

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Abstract

The need to cut down vibration and minimize back pressure wave in a loudspeaker has led to the choice of artificially-made metallic foam structure due to its important low weight, recyclable, stiffness, high surface area, and longer active product life for money. Commercially available highly porous metallic structures are known to be poor sound absorber and there is a possibility that if they can be made by interacting with the shapes and structural properties of this material, they could make useful. Currently available poroacoustic models needed to describe the sound absorption behaviour of porous materials point out the permeability of this structure as the key parameter driving this behaviour. Knowing this parameter through experimentation or prediction is imperative to the design of material with novel attributes for this process.

Pore-level numerical simulation of fluid flow through low-density “bottleneck-type” structures using tomography images of the “real” structures and “unconventional” sphere-packing models have been used herein to account for this permeability with reasonable fit to experimental data of airflow measured across these structures. This parameter was observed to be dependent on the structural parameters of the porous medium and most importantly, its pore diameter openings. Theoretical models to account for flow behaviour of this structure at low and high fluid velocities were proposed. Optimal values of structural parameters needed for the design of “bottleneck-type” structure for efficient sound absorption were achieved for a hardbacked and airgap simulation.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Morvan, Herve P. Kennedy, Andrew R. Simmons, Kathy
Keywords:	Absorption of sound; Porous materials; Aluminum foam
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) T Technology > TA Engineering (General). Civil engineering (General) > TA 365 Acoustics in engineering. Acoustical engineering
Faculties/Schools:	UK Campuses > Faculty of Engineering
Item ID:	53597
Depositing User:	Otaru, Abdulrazak
Date Deposited:	30 Nov 2018 08:34
Last Modified:	25 Jul 2024 15:03
URI:	https://eprints.nottingham.ac.uk/id/eprint/53597

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