본 연구에서는 Fig.1에 보인 바와 같이 원심휀이 부착된 실내 에어콘을 대상 으로 하여 원심휀의 진동.소음 특성을 연구하였다. Fig.2에서 보인바와 같이 원심휀 은 전기 모터 축에 커플링 되어 있으며 원심휀의 회전으로 발생된 공기유동은 연결된 덕트 시스템(duct system)을 통해 외부로 방출 된다. 이와 같은 송풍시스템에서 발 생하는 진동.소음은 크게 구조물 진동에 의한 구조물진동소음과 공기유동 자체에서 발 생하는 공기유동소음으로 구별된다. 본 연구는 실험적 연구를 통하여 이들 진동. 소 음원의 주파수 특성과 전체 소음에의 기여도 등을 규명하였다.
Because of low noise and small size with huge capacity, a centrifugal fan is widely used for ventilation, air-conditioner and so on, which are very near to human life. Because of the complexity of its vibration and noise generation mechanics, most of researches on them are based on experimental methods. This study is to characterize the centrifugal fan noise and vibration. It is considered that noise is composed of the structural vibration noise and the air flow induced aerodynamic noise. To decouple the structural vibration noise the centrifugal fan is masked with an adhesive tape, such that air blowing is prohibited thus only the structural vibration noise is extracted. The noise level and characteristics in the frequency domain are verified and compared with those of total mixed one. This study shows some significant results that the structural vibration noise has relatively narrow band power spectrum compared with the total mixed one and has a strong periodicity. The sound level is lowered about 5dB by the removal of air flow with the masked fan for an air-conditioner used in this study.
