SIMPLE TECHNIQUE FOR ABATEMENT OF NOISE GENERATED FROM AN AIR RING OF A LARGE POLYETHYLENE FILM-BLOWING EQUIPMENT

摘要

This paper presents a simple technique to suppress a high level single-tone sound pressure generated from the air ring of a large polyethylene film blowing machine when operating close to its high output range. SPL suppression obtained was in the order of 27-29 dBA. Analysis showed that the shallow cavity created between the adjustable chimney inner geometry and the fixed chimney of the upper air ring is responsible for a discrete-tone noise around 119 dB. Two positions of the adjustable chimney were found to be responsible for this high single-tone noise. The suppression technique was based on a perforated sliding collar placed around the chimney which has the effects of reducing the initial perforation on the adjustable chimney.