공기청정기의 구조기인소음 저감

Abstract

In this study, we identified structure-born noise in a household air purifier and presented a method for reducing such noise. After noise signals from the air purifier were measured using a microphone, a frequency analysis was conducted to find the source of the noise. To identify the location where the structure-born noise originated, the vibration signals of the scroll were measured, and the frequency components of the measured signals were compared with the noise frequency components. The experimental results confirmed that a forced vibration occurs in the scroll of an air purifier owing to a pressure change caused by the impeller rotation, and this vibration induces the structure-born noise. In addition, modal testing showed that the structure-born noise is amplified when the natural frequency of the scroll radiating the noise coincides with the blade passing frequency. Finally, to reduce the structure-born noise, a damping material was attached to the scroll, and it was then experimentally confirmed that the overall sound pressure level was reduced by 1.2dBA.