Laboratory investigations of low frequency sound attenuation over combustion flat perforated wall sheet

Qin Qin , Philip Rubini , Charith Jayatunga , Victoria Sanderson

Steel perforated liners have been used in turbine combustions for several years. The main purpose of the holes on the chambers is for cooling the combustion wall by inducing cooling air flows through the holes. It would be very useful if the steel perforated liners could be used for attenuating the combustion noise too, especially for the low frequency noise. This paper presents a series of acoustic attenuation measurements which were carried out in a 500 mm (width) × 500 mm (height) × 6000 mm (length) impedance tube on flat perforated steel plates with various geometric parameters. The measured absorption coefficient and impedance show that the steel perforated plates have strong sound attenuation on a certain frequency bandwidth. Experimental data were compared with the predicted data that concerned the effects of air inertia and viscosity in apertures. The results show reasonable agreement with the prediction. The acoustic attenuation properties, inferred from normal surface resistance and absorption coefficient data on perforation panels with different plate thickness, perforation, aperture diameter and aperture distribution are presented. The measurement results and analyses show that with careful design the cooling holes on the combustion wall can be used to attenuate the noise efficiently.

Mots clés: Sound Attenuation; Combustion; Perforated Sheet

Domaines: Acoustique [physics.class-ph]

Qin Qin, Philip Rubini, Charith Jayatunga, Victoria Sanderson. Laboratory investigations of low frequency sound attenuation over combustion flat perforated wall sheet. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00811227⟩