An ultra-thin multi-layered metamaterial for power transformer noise absorption

Abstract

A compact multi-layered structure is proposed based on the coiled-up space concept for power transformer noise absorption at 100 and 200 Hz. Current methods of constructing multi-band absorbers are impractical for power transformer noise control due to the high coupling effect deteriorating their performance. To overcome this shortcoming, the proposed structure is composed of multiple connected layers creating two separate coiled ducts with adjustable dimensions to minimise the coupling effect. In the modelling stage, the geometrical features are optimised using the genetic algorithm to maximise the absorption coefficient and minimise the thickness. The proposed dual-tone absorber has a thickness of 43.5 mm which is significantly thinner than the existing conventional absorbers. The measurement results on a 3D-printed structure demonstrate the feasibility of the design.

Phononic metamaterial for efficient sound attenuation applications

“…Hall et al 25 studied numerically and experimentally Locally Resonant Structures providing a deeper understanding of their limitations and benefits. Based on the coiled-up space concept, a compact multi-layered structure was recently proposed by Sharafkhani 26 for power transformer noise absorption at 100 and 200 Hz. The sound attenuation of an acoustic barrier made with metamaterials was studied by Iannace et al 27 A new type of metamaterial which was made from buttons glued on a polyvinyl chloride membrane has been recently developed.…”